Local flood risk management strategy...Foreword • Local flood risk management strategy •...
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www.portsmouth.gov.uk Local flood risk management strategy
Transcript of Local flood risk management strategy...Foreword • Local flood risk management strategy •...
www.portsmouth.gov.uk
Local flood risk management strategy
2 • Local flood risk management strategy
Foreword • Local flood risk management strategy • 3
ForewordPortsmouth is a densely populated, urbanised island city which has been shaped historically by its relationship with the sea. This relationship will also define our future. Many areas within our conurbation are low lying and protected from flooding by pumped drainage systems and man-made flood defences. Consequently, 12,500 residential properties and over 1,000 commercial properties are currently located in the tidal flood risk zone, with up to another 1000 properties also at risk from surface water flooding. Sea level rise predictions forecast that in 2115 nearly 31,000 residential and 2,000 commercial properties in Portsmouth will be at risk.
Working from guidance given in recent government legislation (The Flood and Water Management Act 2010) this strategy sets out for the first time how Portsmouth City Council works with the Environment Agency, neighbouring local authorities, emergency services and water companies to reduce all forms of flood risk in the city.
Our flooding problems relate to coastal flood risk, surface water and ground water. The strategy sets out to explain these different types of flooding and how we are working to reduce the risk from them. This work will encourage regeneration and bring inward investment to the city as flood defences and drainage networks are improved for the benefit of all. Our strategy focuses on flood risk on a ward by ward basis. It identifies known flooding problems and how we are dealing with them
along with on-going issues where we are working to find a solution. We are already gaining momentum for refurbishment of the sea defences at Southsea and North Portsea Island and fully expect work for Phase 1 at North Portsea to commence in Spring 2015.
Southern Water has also undertaken major work in the city aimed at reducing flood risk to properties from surface water, and we will shortly be investigating levels of groundwater around the city to determine whether or not this will be an increasing problem in the future.
This is an exciting time for Portsmouth and we cannot afford to be complacent. The council will ensure the work we do takes into account all the existing plans we have for regeneration and improvement and we will maximise any opportunity that allows us to work with other organisations both public and private, so we have a safe environment to live and work in.
Whilst flooding can never be fully eliminated, I believe this document, which includes recent revisions relating to the storms in 2014, sets out our plans for the reduction of flood risk and how we are working in a co-ordinated approach with our partners and stakeholders to provide the greatest levels of flood protection possible for the city both now and in the future.
Thank you for your interest in this subject – so often taken for granted, but so important to the future of our city.
David Williams Chief Executive Portsmouth City Council
4 • Local flood risk management strategy • Contents
Contents
Introduction 6
Historic flooding in Portsmouth 9
Location 10
Flood risk in Portsmouth 12
Interactions between different types of flooding 21
Climate change 22
Citywide flood risk measures 24
Contents • Local flood risk management strategy • 5
Flood risk ward by ward 35
Protecting individual residential properties and flood insurance 64
Action plans 66
What you can do to minimise the effects of flooding 72
References 73
Glossary of terms 74
6 • Local flood risk management strategy • Introduction
IntroductionFlooding is one of the biggest natural challenges facing Portsmouth. Our position as a coastal city brings great benefits and these are reflected in the council’s goal to shape the great waterfront city. However, the risk of flooding from the sea, along with that from surface water, are significant issues facing the city due to their potential to threaten people, property and the environment. This risk will increase as a result of climate change. Whilst we cannot entirely eliminate the risk of flooding, this strategy aims to locally manage flood risk for the people, economy and environment of Portsmouth.
Why has the strategy been written?
As a unitary authority, Portsmouth City Council is designated as a Lead Local Flood Authority (LLFA) under the Flood and Water Management Act 2010 (the ‘act’). The act places a statutory duty on LLFA’s to develop, maintain, implement and monitor a Local Flood Risk Management Strategy (hereafter referred to as the ‘strategy’) to manage local flood risk in its area. The strategy aims to locally manage flood risk for the people, economy and environment of Portsmouth by working in partnership to identify and deliver feasible and timely actions.
What are the guiding principles behind the strategy?
The strategy is focused on the following principles as set out in the ‘National Flood and Coastal Erosion Risk Management Strategy (NFCERM)’ with which our local strategy must be consistent.
• Community focus and partnership working
• Catchment and coastal cell based approach
• Sustainability
• Proportionate, risk-based approaches
• Multiple benefits
• Beneficiaries should be allowed and encouraged to invest in local flood risk management
Introduction • Local flood risk management strategy • 7
What is included in the strategy?
The strategy must consider flood risk from surface water, ground water and ordinary watercourses; however, we decided to include coastal flood risk as a major consideration for Portsmouth. It can be difficult to identify the type of flooding during an incident and often it can be a combination of different types. By including all sources of flood risk within this strategy, it provides a clear overview of flood risk within Portsmouth and the co-ordinated approach to managing these risks.
The strategy is also intended to identify projects to reduce flood risk and identify who, how, where and when the projects will take place. This includes referencing projects recently completed, underway or already programmed by the risk management authorities.
How and when will the strategy be reviewed?
The strategy will be treated as a ‘living’ document and will need to be reviewed annually in line with other plans and strategies. The review procedure will be undertaken at Portsmouth City Council’s Flood Risk Strategy Group meetings. If there is a flood event with significant consequences, an ad-hoc review of the strategy may be prompted. The lifetime of the strategy is up to 2018, at which time there will be a major review. The short life-span is due to major investment in coastal defences and drainage over the next five year period.
The document has already been revised to include actions resulting from the storms of winter 2013/14.
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8 • Local flood risk management strategy • Introduction
What are the strategy objectives?
The strategy objectives set out below were agreed by the strategy working group, which included representatives from PCC Drainage, Planning and Coastal teams, the Environment Agency and Southern Water.
1. We seek to improve the knowledge and understanding of all sources of flood risk across Portsmouth, to include (in no particular order of importance):
� Surface water and run-off
� Groundwater
� Ordinary watercourses
� Fluvial (main rivers)
� Coastal
� Reservoir
� Sewer overload
� Mains water supply bursts
2. Identify and work in partnership with other authorities, stakeholders and the community who have a role in flood risk management.
3. Increase public awareness of all flood risk across Portsmouth.
4. Ensure that planning decisions are properly informed by flooding issues, by avoiding development at inappropriate locations and reducing flood risk wherever possible.
5. Maintain, and improve where necessary and affordable, flood risk management infrastructure and systems to reduce flood risk.
6. Identify through an action plan, appropriate measures, and schemes to manage flood risks providing balanced community and environmental benefits, and establish who is responsible for delivery of these measures.
7. Compile a funding plan for schemes listed on the action plan
8. For identified schemes, demonstrate compliance with the EU Water Framework Directive through a Strategic Environmental Assessment and Habitats Regulations Assessment.
9. Detail all procedures in place to mitigate a flood event, including flood response and recovery
Historic flooding in Portsmouth • Local flood risk management strategy • 9
Southsea Common after ‘The Great Gale’, 1910 Broad Street, Old Portsmouth circa 1900-1920
Historic flooding in Portsmouth
Clarendon Road, Southsea, 2000Broad Street, Old Portsmouth 1989
© City Development and Cultural Services, Portsmouth City Council
10 • Local flood risk management strategy • Location
Location
Portsmouth is bordered by four district boroughs, all within Hampshire County Council, which is the designated LLFA for each of these areas. However, as explained later in the strategy, Portsmouth has only minor flood risk interaction with our neighbouring authorities. Comments from the drainage departments in the adjacent authorities are shown overleaf. They describe from a localised perspective, any flooding which may be common with Portsmouth and its neighbours.
© Crown Copyright and database right 2013. Ordnance Survey licence number 100019671.
Location • Local flood risk management strategy • 11
Interactions with surrounding boroughs
i. Havant Borough Council:
Havant has a partial land boundary with Portsmouth, but the southern part of the boundary (Hayling Island) interacts with Langstone Harbour by means of surface water, treated waste water and occasionally in times of extreme weather events, partially treated dilute wastewater which is discharged via consented storm overflows.
Anecdotal evidence indicates that: The Westways estate [Havant Road] drains (foul and storm water) into Portsmouth systems – the storm water goes to the PCC/HBC boundary ditch which drains south under the railway and the A27 into Farlington Marshes. The private drainage from Farlington Redoubt (in HBC’s area) comes into PCC catchment down the access road, and probably so does Fort Purbrook foul water, assuming that’s not on cess pools. Fort Purbrook storm drainage travels north away from PCC.
Reach 3 of the Portchester Castle to Emsworth Coastal Strategy extends into Havant Borough Council catchment by 880m (PCC = 8180m)
Bedhampton Springs, which are the source of Portsmouth’s water supply, are within Havant Borough Council catchment.
ii. Winchester City Council:
Anecdotal evidence indicates that: The River Wallington flows behind Portsdown Hill and into Portsmouth Harbour at Wallington, so this may have an impact on the flow in the harbour but it would be minimal given the harbour’s size.
iii. Fareham Borough Council:
Southern Water have confirmed that there is very little surface or foul water interaction between Fareham and Portsmouth as the western boundary of Budds Farm’s drainage catchment follows Portsmouth City Council’s western administrative boundary.
Reach 1 of the Portchester Castle to Emsworth Coastal Strategy extends into Fareham Borough Council catchment by 3670m (PCC = 1945m)
iv. Gosport Borough Council:
There is no drainage interaction between the catchments as Gosport does not have a land boundary with Portsmouth. Both authorities interact with Portsmouth Harbour by means of surface water, treated waste water and occasionally in times of extreme weather events untreated waste water.
Summary:
Portsmouth has very limited interaction with other boroughs in terms of surface and groundwater. This is due to the topography, geology and the manner in which the drainage system works. Both Portsmouth and Langstone Harbours are tidal and are influenced by the River Walllington and Hermitage Stream respectively. Due to the size of both harbours, the impact of flows from the rivers are minimal and any pollution would be quickly diluted and its effect minimised.
The Portchester Castle to Emsworth Coastal Strategy includes interactions with Fareham and Havant Borough Councils. The Eastern Solent Coastal Partnership working on behalf of the council covers all three areas, allowing the actions for the cells to be addressed across council boundaries.
12 • Local flood risk management strategy • Flood risk in Portsmouth
Flood risk in PortsmouthSurface water
Surface water flooding or surface run-off, is also known as pluvial flooding. This type of flooding occurs when rainfall cannot soak into the ground and then overwhelms the local drains and flows across the surrounding area. This type of flooding is often (but not exclusively) associated with high intensity rainfall and occurs very quickly during or after the rainfall event.
Surface run-off refers to the overland flow of surface water until it reaches a point where it can enter a watercourse or sewer. These flows can be significant depending on their depth, direction and velocity and are represented in Flood Hazard mapping.
Surface water flooding is often quite localised and is much more difficult to predict than river or coastal flooding. There is often limited advance notice of this type of flooding and it generally occurs after prolonged heavy rainfall or high intensity thunderstorm events.
Typical surface water flood incidents in Portsmouth
Flood risk in Portsmouth • Local flood risk management strategy • 13
Surface water flood risk map
An extract from the Environment Agency’s ‘Areas Susceptible to Surface Water Flooding’ (AStSWF) map was used to help determine areas of surface water flood risk for Portsmouth’s Surface Water Management Plan. The map was produced on a national scale using set parameters, and was considered more accurate by the Surface Water Management Plan stakeholders than the ‘Flood Map for Surface Water’ (FMfSW), which was produced as a follow up to the above. There appeared to be more correlation with known flooding issues in Portsmouth with AStSWF.
A further map, the ‘Updated Flood Map for Surface Water’ (uFMfSW), is being produced by the Environment Agency which takes into consideration local level information and modelling. This is was published in December 2013.
These maps are frequently used by the insurance industry to identify properties at risk of surface water flooding.
A road gully not functioning
14 • Local flood risk management strategy • Flood risk in Portsmouth
Coastal flooding
Flooding from the sea (coastal flooding) tends to occur as a result of high tides, surges in sea water and strong winds which raise the sea level above the ground level of the coast or the level of any infrastructure present e.g. flood defences. Coastal flooding can also occur as a result of failure of infrastructure.
Coastal flooding is generally well understood, can be predicted to some extent, and flood protection measures are in place at many locations at risk from this type of flooding.
The Eastern Solent Coastal Partnership currently manages improvements to and maintenance of the majority of the city’s sea defences on behalf of Portsmouth City Council. However, some defences are owned and maintained by third parties e.g. MoD maintain the defences around HM Naval Base.
The main coastal flood risk occurs during a high tide event in stormy conditions with tidal surge and either a south westerley or south easterley storm.
Wave overtopping
Southsea seafront is exposed to the open Solent water where wave action can be heavily influenced by weather conditions and shipping movements. This can give rise to flooding by overtopping of the sea defences, leading to floodwater inundation behind the defences.
Two sections of Southsea frontage are often closed to vehicular traffic by road gates during, or in anticipation of such events, as wave overtopping can spray shingle onto the road, making it unsafe to pass.
NOTE: tide heights are measured in Chart Datum (mCD) around Portsmouth, which can be calculated by adding 2.73m to the Above Ordnance Datum (mAOD) level.
Tidal flood overtopping on the ‘wet’ side of the flood gates at Old Portsmouth.
Shingle on promenade at Southsea following a storm event
Flood risk in Portsmouth • Local flood risk management strategy • 15
Natural habitat migration
Sea level rise and increased storminess
Mean sea level
Saltmarsh erodes at the seaward edge
Saltmarsh ‘migrates’ landwards
Intertidal zone
Coastal squeeze
Sea level rise and increased storminess
Mean sea level
Area ‘squeezed as saltmarsh erodes at the seaward edge
Saltmarsh cannot migrate landwards due to presence of
sea wall
Intertidal zone
Sea wall
Coastal squeeze
Coastal squeeze is the term used to describe what happens to coastal habitats that are trapped between a fixed landward boundary, such as a sea wall, and rising sea levels and/or increased storminess. The habitat is effectively ‘squeezed’ between the two forces and diminishes in quantity and or quality. In the Solent it is the saltmarshes that are perhaps under the greatest threat from this effect. Coastal habitats will naturally adapt to a changing climate by migrating inland but, in highly populated areas like the Solent, there is no room for this process to happen as the land is used for industry, housing or recreation, and will be defended due to its high commercial value.1
Coastal erosion
Coastal erosion is the wearing away of land and the removal of beach or dune sediments by wave action, tidal currents, wave currents, or drainage. Waves, generated by storms, wind, or fast moving motor craft, cause coastal erosion, which may take the form of long-term losses of sediment and rocks, or merely the temporary redistribution of coastal sediments. Erosion in one location may result in an accumulation of the eroded sediment nearby.
Portsmouth’s southern frontage experiences a natural process called ‘longshore drift’, meaning the sediment and shingle on Southsea beach is redistributed over time along the coastline by tidal currents and storms. This effect is regularly monitored to ensure the extent of the erosion is not detrimental. The sediment is redistributed by machinery as necessary.
Defences in Old Portsmouth to prevent coastal erosion
16 • Local flood risk management strategy • Flood risk in Portsmouth
Coastal flood risk map
This map shows Environment Agency Flood Zone 3, which has been produced on a national scale. The hatched area shows the areas that could be affected by flooding, either from rivers or the sea, if there were no flood defences. These areas could be flooded from the sea by a flood that has a 0.5 per cent (1 in 200) or greater chance of happening each year.2
The probability or likelihood of flooding is described as the chance that a location will flood in any one year. If a location has a 0.5% chance of flooding each year, this can also be expressed as having:
• a 1 in 200 chance of flooding in that location in any year
• odds of 199 to 1 against a location being flooded in any year
However, this does not mean that if a location floods one year, it will definitely not flood for the next 199 years. Nor, if it has not flooded for 199 years, will it necessarily flood this year.3
The coastal flood response team (Colas and ESCP) monitoring a high tide in Old Portsmouth
EA flood zone 3 (1/200) 0.5% AEP
© Crown Copyright and database right 2013. Ordnance Survey licence number 100019671.
Flood risk in Portsmouth • Local flood risk management strategy • 17
Local rise in water table due to low permeability obstruction
Groundwater emergence
Water table
Aquifier
Ground levelWater table
Groundwater flowNon-aquifier
Groundwater
Groundwater may be present within permeable geological formations (aquifers) and permeable worked or filled ground (sometimes referred to as made ground). Under certain conditions the groundwater table can rise significantly above its normal level and cause flooding of property and structures both above and below the ground surface. When this happens due to natural processes (rather than a leaking water main for instance) it is known as groundwater flooding.
Groundwater flooding is usually preceded by long periods of heavy rainfall but does not occur rapidly in the same way as fluvial flooding, so the potential hazards to life and health are not as immediate or severe. However, once groundwater flooding has begun, it often takes a long time to recede, and may result in significant property damage and disruption.
A recent groundwater flood event in Portsmouth
18 • Local flood risk management strategy • Flood risk in Portsmouth
Groundwater flood risk map
The map here is a combination of information used to determine groundwater areas for investigation. The Environment Agency ‘Areas Susceptible to Groundwater Flooding’ map was considered too short of detail for Portsmouth, as it was determined on 2km square grids.
This map includes the latest strategic development planning information like the ‘Strategic Housing Land Availability Assessment’ (SHLAA) and Surface Water Management Plan Local Flood Risk Zones (LFRZs).
These areas will be targeted by Portsmouth City Council to determine current and future levels of risk through data monitoring.
25 new borehole sites have been selected by PCC Drainage Team in conjunction with Southern Water, Eastern Solent Coastal Partnership and PCC Planning. Along with a network of existing boreholes, groundwater levels will be monitored to ascertain a trend for groundwater across the city. This will be used to inform:
• Ground contamination levels (at time of borehole installation)
• Relationship to rain and tide events,
• potential sewer infiltration rates
• Suitability of SuDS for new developments
• Influence on flood risk, and
• Influence detailed design of coastal projects
Figure 20 Target Areas and Regions for groundwater flood risk management
2
5
2
1 3
4
7
8
1110
6
9
Tipner
City Centre
48
47
15144
39
159
164
146
143
49
163
152
161
172
165
168
101
85
76
Somerstown and North Southsea
10
178127
176
29
6
02
01
08
04
07
10
0605
09
03
14
13
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11
±0 0.5 10.25
KilometersReproduced from Ordnance Survey material with the permission of Ordnance Survey on behalf of Her Majesty's Stationery Office. © Crown Copyright. Portsmouth City Council, 2013 100019671.
Target Areas for Groundwater Flood Risk Management
Target RegionsTarget AreasSurface Water LFRZs
Strategic Development SitesPortsmouth PlanSHLAA
Flood risk in Portsmouth • Local flood risk management strategy • 19
Sewer surcharge
Sometimes referred to as hydraulic overload or foul flooding, flooding from sewers often occurs at the same time as other types of flooding (particularly surface water flooding) and can be a result of blocked drains or the sewer network being unable to hold all the water flowing into it. It can be identified by water escaping from a manhole. This type of flooding is the responsibility of the pipework owner, normally the local sewerage company. Portsmouth City Council maintains good working relationships with Southern Water and assist them in the investigation of any flooding from sewers.
A sewer manhole surcharging in Portsmouth
Great Salterns Drain, an EA designated main river
Fluvial flood risk (rivers)
Fluvial flooding is also known as river flooding. It occurs when a river cannot hold the volume of water which drains into it from the surrounding land (known as a catchment) as water is not able to be conveyed within the channel and overflows onto the adjacent floodplain. In the context of this strategy, we refer to fluvial flooding as flooding from main rivers. A ‘main river’ is defined in the Water Resources Act 1991 as ‘a watercourse shown as such on a main river map and includes any structure or appliance for controlling or regulating the flow of water into, in or out of the channel’. Portsmouth has two designated main rivers (Great Salterns Drain and Farlington Marshes Gutter), but neither effect properties during a flood event as they are in floodplains which have no development.
20 • Local flood risk management strategy • Flood risk in Portsmouth
Ordinary watercourses
An ‘Ordinary watercourse’ is defined in the act as ‘a watercourse that does not form part of a main river’. This includes lakes, ponds or other areas of water that flow into an ordinary watercourse. Portsmouth has a small number of ordinary watercourses, which do not pose a flood risk to properties.
Reservoirs
The Reservoir Act 1975 states ‘a reservoir is a ‘raised reservoir’ if it is designed to hold, or capable of holding, water above the natural level of any part of the land adjoining the reservoir’.
Portsmouth Water operates one underground reservoir within Portsmouth’s catchment which according to the act does not require consideration as a flood risk as it is below ground.
Water mains
The act also states that ‘a flood caused by a burst water main’ is not required for flood risk consideration. This is because burst water mains are almost impossible to predict and generally occur randomly, most likely as a result of infrastructure failure.
A new watercourse on Great Salterns Golf Course
Aftermath of a burst water main. Debris, water and sunken footpaths are visible
Reservoir and burst water main flooding are not investigated in Portsmouth’s strategy. Main river and ordinary watercourse flooding is also considered low risk and are not actively investigated in the strategy.
Interactions between different types of flooding • Local flood risk management strategy • 21
Interactions between different types of floodingThe interaction between different water sources can have an impact on flooding. These are explained below:
Surface water and groundwater Differentiating between groundwater flooding and surface water which cannot infiltrate can be difficult. Groundwater flooding need not occur after a local rainfall event; rainfall falling further away may cause groundwater levels to rise over a much wider area, e.g. due to an extensive aquifer, and thus cause groundwater flooding at other locations. Again, if the ground is already saturated and causing groundwater flooding, then any further local rainfall will be unable to infiltrate and result in surface water flooding. PCC has experienced a groundwater flood incident (95% certainty) in Baffins ward in early 2013.
Surface water and tide Surface water flooding is also exacerbated at locations where seepage occurs beneath the defences, which contributes to maintaining a high water table. The ground geology indicates that this may be the case on the southern part of Portsea Island, which would result in high groundwater levels at Southsea. ‘Tidelocking’ can also occur, when a gravity flow surface water network cannot discharge to the sea during a high tide. This causes surface water to back up and increasing flood risk. Tidelocking is exacerbated by sea levels if sea water is not prevented entering the sewer through the outfall e.g. dysfunctional flap valve.
Surface water and sewer surcharge Large parts of Portsea Island are served by combined sewers. This means surface water uses the same trunk sewers as foul water, during a rain event diluted foul water may be surcharged from a combined sewer manhole. This poses a health and safety concern and often results in a lengthy and costly clean up operation.
Groundwater and sewer surcharge Many of Portsmouth’s sewers are of Victorian brick construction and are liable to groundwater ingress, especially those at significant depth from the surface. If the pipe joints are not properly sealed, ground water enters the sewer network reducing its capacity and increasing flood risk. It is difficult to quantify the amount of groundwater in the sewers. Southern water have recently completed sewer lining in Old Portsmouth to prevent seawater infiltration to the sewers
Groundwater and tide Tidal levels are often mirrored in groundwater levels. High tides can mean high groundwater levels especially in proximity to the coast. This can be difficult to quantify as considerations such as the permeability of the sub-soil and the condition of sea defences are recognised as having an influence. Generally there is a slight time delay between peak tide level and peak groundwater level.
1.00
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Wat
er L
evel
(m
)
Time
Old Portsmouth Tide and Ground Water Level (GWL) comparison
25 November 2009 to 30 November 2009
Recorded Borehole GWL (mCD)
Sea Level (mCD)
22 • Local flood risk management strategy • Climate change
Evidence:
There is clear scientific evidence that global climate change is happening now. It cannot be ignored.
Over the past century around the UK we have seen sea levels rise and more of our winter rain falling in intense wet spells. Seasonal rainfall is highly variable. It seems to have decreased in summer and increased in winter, although winter amounts changed little in the last 50 years. Some of the changes might reflect natural variation; however the broad trends are in line with projections from climate models.
Greenhouse gas (GHG) levels in the atmosphere are likely to cause higher winter rainfall in future. Past GHG emissions mean some climate change is inevitable in the next 20-30 years. Lower emissions could reduce the amount of climate change further into the future, but changes are still projected at least as far ahead as the 2080s.
We have enough confidence in large scale climate models to say that we must plan for change. There is more uncertainty at a local scale but model results can still help us plan to adapt. For example we understand rain storms may become more intense, even if we can’t be sure about exactly where or when. By the 2080s, the latest UK climate projections (UKCP09) predict that there could be around three times as many days in winter with heavy rainfall (defined as more than 25mm in a day). It is plausible that the amount of rain in extreme storms (with a 1 in 5 annual chance or rarer) could increase locally by 40%.
One example of climate change occurring is the increasing frequency of closures of the Thames Barrier. This clearly shows four closures in the whole of the 1980s, rising to 19 separate closures in 2003 alone and five for just the first three months of 2010.
Climate change
YearClosures due to
Total closuresTidal flooding Fluvial flooding
1983 1 0 1
1984 0 0 0
1985 0 1 1
1986 0 0 0
1987 1 0 1
1988 1 0 1
1989 0 0 0
1990 3 3 6
1991 0 0 0
1992 0 1 1
1993 5 4 9
1994 1 0 1
1995 3 2 5
1996 4 0 4
1997 0 0 0
1998 3 0 3
1999 3 3 6
2000 4 6 10
2001 11 4 15
2002 2 2 4
2003 11 8 19
2004 2 0 2
2005 5 0 5
2006 1 0 1
2007 11 0 11
2008 3 0 3
2009 1 4 5
2010 (up to 20 March) 0 5 5
Total 76 43 119
Thames Barrier Closures 1983 – 2010 4
Climate change • Local flood risk management strategy • 23
The future:
The current National Planning Policy Framework is likely to be replaced. Following an external review, ministers have proposed a new streamlined planning practice that will provide support for the growth and creation of jobs and homes that the country needs. It will also provide clearer protections for our natural and historic environment by giving power back to communities who are generally best placed to make local decisions.5 This is currently in the public domain for consultation and comment.
In order to allow consideration of the effects of climate change, Map Set 1E of the Partnership for Urban South Hampshire Strategic Flood Risk Assessment shows revised outlines for Flood Zones 2 and 3 for a number of years over the next century. The outlines were produced for 2025, 2055, 2085 and 2115. This is in line with recent Defra guidance on climate change, which provided allowances for sea level rise to 2025, 2055, 2085 and 2115 and indicative sensitivity ranges for increased river flows due to climate change from 2025 onwards.
In tidal areas, these climate change outlines were derived by projecting the Environment Agency extreme sea levels inland, using a methodology defined by the Environment Agency.
The map here shows the extent of Flood Zone 2 or 3 in the year 2115, given the predicted impacts of climate change. Although planning decisions are taken using the present day Flood Zones, PPS25 states that flood risk should be considered throughout the lifetime of a development. In certain areas, climate change may mean that the flood zones could encroach upon areas that would otherwise be considered suitable for development. This may be an important issue for local planning authorities. At the sub-regional scale, the climate change outlines can be used to show which areas of the sub-region are most vulnerable to rising sea levels, indicated as those areas where there is greater variation between each climate change outline from 2025 to 2115.
© Crown Copyright and database right 2013. Ordnance Survey licence number 100019671.
24 • Local flood risk management strategy • Citywide flood risk measures
Citywide flood risk measuresPortsmouth City Council departments that help reduce flood risk and howPortsmouth City Council has a number of measures in place to mitigate the risk of flooding. These range from planning policies to management and reactive actions in response to a flood event.
PCC seafront management
The Seafront Masterplan is intended to guide improvements to the seafront area of the city, which stretches for 3.7km between Portsmouth and Langstone Harbour entrances. It contains proposals that respond to the overarching vision and aims of the Seafront Strategy. In the context of the Local Flood Risk Management Strategy, ‘the plan seeks to establish a high quality baseline for proposals including design principles …’
It is anticipated that detailed proposals for enhanced coastal defences at the seafront will be informed by the masterplan which identifies opportunities to utilise coastal defence structures to deliver wider benefits to the public in terms of amenity and aesthetics. The Seafront Masterplan is wholly within Flood Cell 1 of the Portsea Island Coastal Strategy, which has attracted funding for improved sea defences.
Colas (contractors working with PCC on PFI agreement)
• Gully cleansing programme, especially in autumn leaf fall period.
• Maintain PCC owned drainage assets e.g. highway drainage.
• Coastal flooding response team for the Coastal Partnership.
Citywide flood risk measures • Local flood risk management strategy • 25
PCC Drainage Team
The act imposes a number of new duties on PCC as a Lead Local Flood Authority. The Drainage Team undertakes many of these duties.
Statutory duties:
• To prepare a Local Flood Risk Management Strategy (FWMA S9).
• To investigate flood incidents (FWMA S19).
• To establish and maintain a register of structures that affect flood risk (FWMA S21).
• To designate third party assets that affect flood risk and give notice to owners that they have been designated (FWMA Schedule 1).
• Responsible for consenting and enforcing works on ordinary watercourses (FWMA Schedule 2 Para. 33).
• New role as SuDS Approval Body (SAB) requiring LLFA to approve, adopt and maintain SuDS on new developments (FWMA Schedule 3).
• Prepare a Flood Hazard map (FRR Part 3).
• Prepare a Flood Risk Management Plan (FRR Part 4).
Other duties:
• Checking areas of the city susceptible to flood risk.
• Respond to flooding incidents in the city.
• Vital role in setting up and running of the emergency response room during heavy rainfall events and co-ordinating the response with contractors.
• Seek external funding through Environment Agency Flood Defence Grant in Aid (FDGiA) scheme for major schemes.
• Work with Eastern Solent Coastal Partnership in overlapping matters.
• Design solutions to improve the drainage capability of the city.
• Assist TES Major Projects with drainage requirements (Technical advice and Guidance – e.g. Tipner, Northern Road Bridge).
• Act as a liaison between Southern Water, the Environment Agency, PCC departments and elected members (e.g. Southern Water surface water separation schemes).
• Work with Colas to identify localised flooding and suggest possible remediation / mitigation measures.
• Increase resident understanding of local flood risk.
• Increase our historic knowledge of Portsmouth drainage in liaison with the central library and city museum.
• Continue works as a shared service with Southampton City Council and Isle of Wight.
• Respond to residents’ enquiries with regards to flood and drainage.
• Promote SuDS.
• Promote schemes which reduce flood risk.
• Promote Flood Action Group (FLAG) schemes with the EA.
• Investigate unresolved flooding issues
CITY OF PORTSMOUTHSURFACE WATER FLOODING NOTES
Rain event of 6 October 2014
POINTS ADDED SINCE 5jan2012 MAP
23c - London Road at bus stops outside 99p shop23d - Emsworth Road
© Crown Copyright and database right 2014. Ordnance Survey licence number 100019671.
26 • Local flood risk management strategy • Citywide flood risk measures
The Eastern Solent Coastal Partnership
The Coastal Partnership was formed through a shared service agreement signed in April 2012 between the four local authorities of Portsmouth City Council, Havant Borough Council, Gosport Borough Council and Fareham Borough Council.
The Coastal Partnership’s work, on behalf of the council is:
Reduce the risks to people and the developed and natural environment from flooding and coastal erosion by encouraging the provision of technically, environmentally and economically sound and sustainable defence measures along the entire 162km coastline contained within the Coastal Partnership’s authority boundary. This is achieved by undertaking a number of functions:
• ensure the development of strategic plans for the future management of the coastline and ensure their implementation.
• ensure that any development within the coastal zone does not adversely effect the environment.
• ensure that any development within the coastal zone does not disrupt natural processes, such as the transport of sediment along the shoreline.
• avoid committing future generations to inflexible and expensive options for coastal defence.
• monitoring the evolution of the coastline and the forcing parameters affecting it.
The Coastal Partnership also works to protect assets against coastal erosion and flooding from the sea, without conflicting with the above.
The Coastal Partnership surveys and carries out research relating to coast protection and sea defence; designs and supervises new sea defence and coast protection projects; arranges and supervises coastal protection works and advises private individuals on minor problems with coast protection and flooding where these are the consultee’s responsibility.
The Coastal Partnership maintains this with the help of land owners whose land adjoins the shoreline.
The Coast Protection Act 1949 and the Land Drainage Act 1991, provide maritime Councils with permissive powers to carry out coastal defence works. Coastal defence is an encompassing term for both ‘coast protection’ and ‘sea defence’; where coast protection is the protection of the land from the risk of erosion and sea defence is the defence against the risk of flooding by the sea.
A major task is the production of Management Plans in association with the Environment Agency (EA). Shoreline Management Plans, Flood and Coastal Erosion Risk Management Strategies and Beach Management Plans contribute to the continuing maintenance of the Borough’s assets and protection of property. The Plans are used to provide the framework within which maintenance works and new schemes are identified and prioritised. The Department for Environment, Food and Rural Affairs ( DEFRA ) can award Capital Grant towards Strategies, preliminary studies and Capital Schemes.
More information about the Eastern Solent Coastal Partnership can be found at the following link: www.escp.org.uk
Citywide flood risk measures • Local flood risk management strategy • 27
• Requiring surface water to be separated within the site and the post development rate of discharge of both surface and foul water to the combined system should be no greater than the existing rate.
• Mitigating the residual flood risk that remains after other steps have been considered by ensuring that the design and layout of development minimises the risk to people and damage to property in the event of flooding and having in place effective emergency response plans.
Other policies in the Portsmouth Plan also contribute, more indirectly, to the management of flood risk: Policy PCS15 – Sustainable Design and Construction expect new development to meet BREEAM or Code for Sustainable Homes standards, which include measures on water efficiency, flood risk and drainage; and Policy PCS13 – Greener Portsmouth protects open spaces from development, encourages green roofs and green walls in new development and requires new open space to be provided in larger new developments, all measures which help with effective drainage across the city.
The Community Infrastructure Levy (CIL) is a new levy that PCC can choose to charge on new developments in their area. The money can be used to support development by funding infrastructure that the council, local community and neighbourhoods want, this includes flood defence structures.
PCC planning
The Portsmouth Plan, the strategy for development in the city up to 2027, includes two specific policies that influence how flood risk is considered in new development:
Policy PCS12 (Flood Risk) confirms that the council, in planning future development in the city, will follow the flood risk management hierarchy establish in Planning Policy Statement 25: assess, avoid, substitute, control, mitigate. This applies both to plan making and to the determination of planning applications. The council through this policy has committed to:
• Assessing the level of flood risk in making allocations for development, and avoid flood risk by prioritising those sites for development which are at lower risk of flooding.
• Assessing the level of flood risk in considering planning applications and requiring the development to demonstrate that it will be safe over its lifetime. Where necessary, controlling flood risk on individual sites through on site flood risk management measures.
• Maintaining and improving the city’s flood defences; and seeking contributions towards flood defences from development.
• Seeking opportunities to improve the capacity problems of the existing sewer system, including through the promotion of a link separating the mainland waste water from Portsea Island wastewater.
• Permitting new developments only where the necessary surface water drainage, foul drainage and sewage treatment capacity is available, or where additional capacity will be provided in time to serve any individual phase of the development without unacceptably reducing the level of service to existing users, or causing harm to the environment.
1
The Portsmouth Plan
Portsmouth's Core Strategy
www.portsmouth.gov.uk
28 • Local flood risk management strategy • Citywide flood risk measures
The South East 7
PCC sits on a panel of LLFAs called the South East 7, which includes all the unitary and county authorities from the South East stretching from Hampshire through to Kent. As a joint venture, the SE7 has delivered a Sustainable Drainage System (SuDS) Masterplanning Guidance document for all those connected with implementing new developments. The document is intended to provide a blanket for SuDS across the whole of the South East, giving consistent guidance to developers on how to address and choose SuDS under differing site conditions.
The SuDS Approval Body
Under the Act, Portsmouth City Council has a duty to implement a SuDS Approval Body (SAB) which is tasked with reviewing drainage submissions of new developments. This is in addition to the existing planning process. The SAB will have the power to refuse a planning application on drainage grounds alone, and can also inspect the construction of a drainage system to ensure it is built as designed and as approved by the SAB. This duty is presently still not enacted, and is currently under consultation.
Highways
• Incorporate SuDS in all major highway development in conjunction with LLFA.
• Promote impermeable paving and reduce hard standing areas.
• Work with Southern Water to reduce water flow into sewers.
Civil Contingencies Unit
• Preparation of Multi Agency Flood Plan and Flood Response Plan.
• Inform the public on how to prepare for and manage a flood event.
• Circulate Met Office weather warnings.
PCC Flood Risk Strategy Group
A biannual meeting of Risk Management Authorities held at the Civic Offices between PCC elected members, strategic directors, PCC Planning, PCC Drainage, Eastern Solent Coastal Partnership, Environment Agency and Southern Water to inform and update on progress in matters relating to flooding.
Partnership for Urban South Hampshire (PUSH)
PUSH is a partnership dedicated to delivering sustainable, economic-led growth and regeneration to create a more prosperous, attractive and sustainable South Hampshire offering a better quality of life for everyone who lives, works and spends their leisure time here.
Working in partnership, PUSH is determined to tackle these issues and bring about a renaissance of the cities of Southampton and Portsmouth as well as some of our older urban areas.6
MAFP June 2011, due for review 2014FRP June 2009, due for review 2014
Citywide flood risk measures • Local flood risk management strategy • 29
The table below shows how activities can affect water quality in bodies, like the harbours.7
Local authority functions and services
Point source pollution
Urban diffuse pollution Rural diffuse pollution e.g. from agriculture, septic tanks, etc
Physical man-made modifications to water bodies
Low flows in water bodies
Habitat degradation e.g. invasive non-native species
Polluted runoff from impermeable urban surfaces
Drainage/sewerage e.g. misconnections, etc
Sediment run-off from land e.g. pollution down surface water drains
Littering, dumping and general neglect of watercourses
Pollution from contaminated land, including disturbance during development
Local planning policies ◊ ♦ ◊ ◊ ♦ ♦ ◊ ◊Determination of planning applications and building control inspections
◊ ♦ ♦ ♦ ◊ ♦ ◊ ♦ ◊ ◊
Local authority drainage and flood risk management functions, and future SuDS approval body role
◊ ♦ ♦ ♦ ◊ ♦ ◊ ◊
Environmental health and pollution control functions
◊ ♦ ♦ ◊ ◊ ◊
Managing local authority buildings and assets
◊ ♦ ♦ ◊ ◊ ◊
Open space and green infrastructure, ecology and recreation
♦ ♦ ♦ ◊ ◊
Highways design, maintenance and cleansing operations
♦ ◊ ◊ ◊ ◊
Local authority community leadership and advocacy roles, including education
♦ ♦ ◊ ♦ ◊ ◊ ◊ ◊
♦ = has significant potential effect on causes of poor water body status ◊ = has less significant potential effect on causes of poor water body status
Business as usual functions of Portsmouth City Council and their potential water environmental impacts
30 • Local flood risk management strategy • Citywide flood risk measures
The Environment AgencyThe Environment Agency is responsible for managing warnings of potential tidal and fluvial flooding. The flood warning system is based on geographical flood warning areas and indicates the level of predicted risk. It advises the public and responders on the likelihood of flooding through a staged approach to warning and taking action. The Environment Agency has split the coastal floodplain in Portsmouth into warning areas, based on the level of defences and flood risk.
The Environment Agency uses three flood codes to indicate the level of predicted risk: flood alert, flood warning and severe flood warning.
Flood warnings are issued directly to the public, responders and the media through a 24-hour warning system called Floodline Warnings Direct. If a flood warning or severe flood warning is issued in the Portsmouth area a recorded message is sent directly to all landline numbers, including ex-directory, in that flood warning area. Members of the public and businesses can also sign up to receive warning messages through phone, fax, text, email or pager. Members of the public can also call the EA 24-hour phone line Floodline service, where they can listen to recorded information about flood warnings in force or speak to an advisor on 0845 988 1188.
When the flood threat has receded the EA will issue Warning Removed messages. This will tell people the flood threat has passed and no further flooding is expected in their area. They will be issued through Floodline Warnings Direct, Floodline and the internet.
The Environment Agency is the operating authority for flood defences on designated main rivers:
Environment Agency main rivers
• Great Salterns Drain
• Great Salterns Drain (tidal)
• Farlington Marsh Gutter
• Farlington Marsh Gutter (tidal)
• River Wallington (tidal) – flows into Portsmouth Harbour
• Hermitage Lake (tidal) – flows into Langstone Harbour
© Crown Copyright and database right 2013. Ordnance Survey licence number 100019671.
Citywide flood risk measures • Local flood risk management strategy • 31
Reducing the risk of flooding
• Building river and sea defences.
• Warning when flooding is expected from rivers or the sea.
• Helping people understand what they can do to protect themselves and their property from flooding.
• Helping the emergency services during a flood.
• Working with local councils and water companies to reduce the risk of flooding from heavy rainfall.
• Advising local councils on whether proposals for new buildings will increase the risk of flooding.
• Using science and research to identify areas at risk from flooding and plan the best ways of reducing flooding in the future.
• Advising government on policies affecting the risk of flooding.
• Working closely with the Met Office, who provide weather forecasts and warn when heavy rain is expected.
Protecting the environment
• Ensuring that farms, factories and other businesses don’t release too many chemicals into the air, rivers and streams or land. We work with people to help them meet their legal responsibilities, and we prosecute anyone who wilfully breaks the law and damages the environment.
• Licensing waste processing centres, such as recycling centres, rubbish dumps and waste incinerators. Before granting a licence, we assess whether they meet strict environmental standards, and then we make sure they continue to meet them.
• Licensing the removal of water from rivers and underground, to make sure there is enough water for wildlife as well as for homes, farms, factories and other businesses. Every drop of water you use at home and work is taken from the environment, and we make sure water companies are able to supply their customers without harming the environment.
• Carrying out scientific research to set standards for the quality of air, land and water, and prove whether these standards are being met. Our advice to government and businesses is based on sound science.
Improving the environment
• Cleaning up after major pollution incidents, such as chemical spills on land or in rivers, and cleaning up places damaged by industry or neglect in the past.
• Working with conservation organisations to create and restore important wildlife habitats, and protect the plants and animals that live in them. Habitats include rivers, ponds, pastures, marshes, mudflats and woods.
• Licensing fishing by rod in all of England and Wales. The fees help pay for work to make rivers a healthy place for fish and other wildlife to live, and mean that people can continue to enjoy fishing.
• Licensing boating for the Thames and some rivers in Kent and East Anglia. We charge boat registration fees to help pay for work to keep these waterways open for boats to use.The Environment Agency responding on site to a flood event © Eastern Solent Coastal Partnership
32 • Local flood risk management strategy • Citywide flood risk measures
Adapting to climate change
New flood defences must be able to cope with future rises in sea levels, as well as current conditions. Science is at the heart of everything we do, and our plans are based on solid scientific research.
Reporting incidents and emergencies
The EA deals with things that affect the natural environment. Other organisations deal with buildings, roads, the water supply and keeping the neighbourhood safe and clean.
Business as usual
• Prepare and maintain Hampshire Local Flood Warning Plan.
• Contribute to multi-agency plans.
• Maintain EA duty officer procedures.
• Update flood risk maps for coastal and fluvial flooding.
• Maintain EA flood defence.
• Maintain and operate Eastern Road pumping station.
• Maintain and clear grills on Great Salterns Lane.
• Monitor fluvial and coastal conditions.
• Respond to pollution incidents.
Moderate flood risk
• Issue Operational Instructions to Portsmouth City Council indicating levels reached for gate closure.
• Issue Flood Alerts to professional partners on flood risk.
• Provide advice to professional partners on flood risk.
• Consider contacting Response Working Group Local Resilience Forum partners to discuss activation of Adverse Weather Office.
• Record details of flood events
Substantial flood risk
• Issue flood warnings to professional partners, media and at risk members of the public via Floodline Warnings Direct.
• Contact Response Working Group Local Resilience Forum partners to discuss activation of Adverse Weather Office.
Severe flood risk
• Issue Severe Flood Warnings to professional partners, media and at risk members of the public via Floodline Warnings Direct.
• Contact police and other partners to discuss activation of the Strategic Control Group.
Flood waters receding
• Review EA duty officer procedures.
• Record locations of coastal/fluvial flooding.
• Advise on waste disposal issues.
EA live flood warnings link
Go to www.environment-agency.gov.uk and search ‘live flood risk map’.
Strategic overview:
• Co-ordinating flood and coastal erosion risk management activities.
• Provide flood warning service.
• Support emergency responders during a flood.
• Managing flood risk from main rivers, estuaries, the sea and reservoirs.
• Planning flood risk management activities.
• Power to undertake works to reduce flood risk.
• Power to designate features.
Citywide flood risk measures • Local flood risk management strategy • 33
Hampshire ConstabularyResponding to a severe flood event.
• Activate Hampshire and Isle Of Wight (HIOW) Local Resilience Forum (LRF) strategic multi-agency management.
• Provide chair of Strategic Control Group (SCG).
• Co-ordinate media and public information in accordance with HIOW LRF Media Plan for Major Incidents.
• Liaise with Highways Agency, local highways authorities and co-ordinate resources to minimise disruption on the highways and maximise emergency services access.
• Assist with co-ordinated risk assessed evacuations.
• Set up casualty bureau documentation teams as appropriate.
• Notify Special branch who will assess the potential impact on any Critical National Infrastructure sites within HIOW.
Hampshire Fire and Rescue ServiceResponding to a severe flood event:
• Activate HIOW LRF strategic multi-agency management.
• Assist in the co-ordination of media and public information in accordance with HIOW LRF Media Plan for Major Incidents.
• Continue with co-ordinated risk assessed evacuations, implement long term flooding protocols.
Hampshire Constabulary responding to a flood event © The Eastern Solent Coastal Partnership
Hampshire Fire and Rescue Service clearing a flood in The Phoenix’s basement, Duncan Road, Southsea
34 • Local flood risk management strategy • Citywide flood risk measures
Southern WaterSouthern Water collects and treats waste water (including surface water) in Portsmouth. It owns and maintains a range of assets which are essential to effective flood risk management in the city. These assets themselves may be affected by surface water and groundwater flooding in some instances. Southern Water is the licensed sewerage undertaker regulated by the Environment Agency and, financially regulated by Ofwat.
Southern Water is expected to take a lead in resolving all failures of the sewerage service irrespective of cause. SW will liaise with other agencies as necessary to effect a solution leading to a number of partnership schemes with both surface water and sewerage benefits in due course.
Responding to a severe flood event
• Implement incident team.
• Incident team liaise with police and Portsmouth City Council to implement appropriate multi-agency level of management.
• Activate severe weather plan.
• If activated, send representative to SCG.
• Increase standby staff if possible.
• Check plans for detailed actions for high risk assets/areas.
• Provide advice to the public as developed and agreed by the STAC.
Surface water separation
Southern Water has delivered a £20m investment, which included surface water separation schemes to reduce the risk of sewer flooding in parts of Portsmouth and Southsea. The scheme diverts a significant amount of rainwater away from combined sewers by sending it to the sea, as well as refurbishing some of the existing equipment on the network, including the construction of two new underground pumping stations. This work benefits the whole city but in particular, those areas that have suffered flooding in the past.
The new well in Stamshaw Park, Gruneisen Road scheme
A petrol interceptor being installed, Copnor Road scheme
Flood risk ward by ward • Local flood risk management strategy • 35
Flood risk ward by wardHow to use the ward pagesOur strategy has taken the approach of considering each of the 14 wards individually for ease of reference. The information for each ward has been set out as follows:
38 • Local flood risk management strategy • Baffins
BaffinsBaffins ward is located on the eastern side of Portsea Island and is predominantly of low topography. There are large open spaces in the form of the southern side of Great Salterns golf course, Milton Common, allotments and various other green spaces. The developed area is largely set back from the coast to the west of Eastern Road. The coastline runs from the Harvester to Milton Common on Langstone Harbour frontage. The ward also includes Great Salterns Lake which acts as the main surface water drainage outlet for approximately one quarter of Portsea Island. The lake and its tributary culvert feeding into it from the golf course to the north are designated as a main river. It has pumps which trigger at a certain water level in times of high tide.
Flooding
Baffins ward has a number of separate surface water drainage networks but is largely served by combined drainage networks. Baffins ward forms part of two separate areas identified for targeted groundwater investigation.
There are a few pockets of surface water flooding recorded, and there have been incidents of wave overtopping along the Eastern Road frontage which causes disruption to one of the arterial roads of Portsmouth. It is highly likely that there was groundwater influence on one of the more recent events.
This area features in the Portsea Island Coastal Strategy Study – actions are outlined on the next page.
Key
PICSS flood cell 4
Ward boundary
areas targeted for groundwater investigation
SWMP hotspots
Wave overtopping along the Eastern Road frontage
4j
4i
3h
8
5
4
Ward name
Baffins • Local flood risk management strategy • 39
Coastal
AreaOverlap with other wards
Sea defence type(s)
Background information
Residential properties presently at risk (0.5% annual probability flood)
Proposed measures (target standard of protection 0.5%)
Responsible authority
Completion date
Funding
Milton Bund to Tangier Road seawall (4i)
n/a Seawalls, revetments, embankments
Frontage protects to residential properties and Milton Common (former landfill site). Existing standard of protection 0.5%)
23 Raise crest wall and embankment, provide shoreline protection
PCC 2017 Flood Defence Grant in Aid
Eastern Road bridge to Great Salterns Quay (4j)
Copnor Seawalls, revetments
Frontage protects to A2030, golf course, housing estate and some commercial properties. Existing standard of protection 0.5%.
Strengthen existing walls and raise defences to provide a sustained standard of protection accounting for sea level rise.
PCC 2017 Flood Defence Grant in Aid
Surface
Surface water management plan area
Overlap with other wards
Background informationProperties presently at risk (1% annual probability rain event)
Historic flood records
Proposed measures Project leadCompletion date
Residential Commercial
8 – Great Salterns golf course
n/a Golf course regularly floods when EA main river running through the centre of the course bursts its banks
1 11 Good Great Salterns Scheme addressing the issues. Additional storm water channel, additional culvert and upgrade of existing pumping station
Southern Water
by 2015
Tangier Road (not in SWMP)
n/a Southern Water have identified a scheme to remove surface water from the combined sewer network
n/a n/a Some Tangier Road Scheme under construction Southern Water
by 2015
Total 1 11
Groundwater
Groundwater desktop study targeted area
Overlap with other wards
Background information Proposed measures Project leadCompletion date
5 – Great Salterns
Copnor Low topography, likely to have high groundwater table. Highlighted as susceptible to groundwater emergence due to a geological permeability boundary
Determine and agree with partners how best to gather groundwater information and exactly where within the area
PCC with support requested from Environment Agency, Southern Water, PCC planning department, Eastern Solent Coastal Partnership
end 2014
4 – Milton Milton Low topography, likely to have high groundwater table. Highlighted as susceptible to groundwater emergence due to a geological permeability boundary
Determine and agree with partners how best to gather groundwater information and exactly where within the area
PCC with support requested from Environment Agency, Southern Water, PCC planning department, Eastern Solent Coastal Partnership
end 2014
Stanley Avenue n/a Flooding to garages along the rear access road. Investigations have found that the likely source is groundwater with 95% surety.
PCC is investigating possibilities PCC end 2014
Coastal flood risk table with actions, responsible authority and funding information
Surface water flood risk information with actions
Areas identified for groundwater investigation and monitoring
Brief overview of the ward characteristics including some of the defining areas
Aerial shot of the ward showing Surface Water Management Plan Local Flood Risk Zones, areas identified for groundwater investigation and coastal flood cells
Brief overview of the ward drainage and coastal characteristics, and an overview of flooding that has occurred historically
Photo showing an example of flooding or flood aftermath within the ward
Abbreviations
PEMS: Portchester Castle to Emsworth Coastal Strategy PICSS: Portsea Island Coastal Strategy Study SWMP: Surface Water Management Plan FBC: Fareham Borough Council HA: Highways Agency HWT: Hampshire and Isle of Wight Trust
NOTE: Only short term actions are shown as the strategy is due to be reviewed in 2018. For medium and long term actions please refer to PICSS / PEMS.
36 • Local flood risk management strategy • Paulsgrove
1
11
PaulsgrovePaulsgrove ward is dominated by the side of Portsdown Hill and the M27 which splits the densely populated area into two sections. There are large open spaces towards the top of the hill, King Richards and St Pauls schools, Port Solent and along Southampton Road frontage.
The south coast railway line runs through the south of the ward. The coastline is wholly within Portsmouth Harbour and includes Trafalgar Wharf, Southampton Road, Port Solent and Horsea Island.
Flooding
Paulsgrove has largely separate surface water drainage networks with sparse records of surface water flooding, most of which are likely to be caused by localised issues like blocked gullies.
There have been historical incidents of wave overtopping along Southampton Road frontage which causes localised disruption to traffic and residential areas along the frontage.
The area to the south of the railway line has been identified for targeted groundwater investigation.
This area features in the recently approved Portchester Castle to Emsworth Coastal Strategy – actions are outlined on the next page.
Key PEMS flood cell 1a
PEMS flood cell 1b
PEMS flood cell 2
PEMS flood cell 3
Ward boundary
areas targeted for groundwater investigation
SWMP hotspots
Southampton Road frontage after a combined high tide and storm event
Paulsgrove • Local flood risk management strategy • 37
Coastal
AreaOverlap with other wards
Sea defence type(s)
Background information
Dwellings presently at risk from a 0.5% annual probability flood event
Proposed measuresResponsible authority
FundingCompletion date
Portchester to Paulsgrove (Reach 1)
Fareham Borough Council
Concrete wall, concrete bag wall, revetment, embankment and sheet piling
Frontage provides protection to residential and commercial properties and A27. Defences in good to fair condition. Present standard of protection 5-10%
66 (408 across entire flood cell)
Raise defences to interim height from Portchester Castle to Paulsgrove
EA/English Heritage/PCC/FBC
Medium likelihood of funding through Flood Defence Grant in Aid. Contributions likely to be required. Any development of the Trafalgar Wharf site, included in the draft Site Allocations document, could be a potential source of funding
Works required by 2020
Horsea Island (Reach 2)
n/a Concrete block revetment (Port Solent), Gabions (MoD and landfill site)
Frontage provides erosion protection to landfill site. Defences in very good to good condition. Present standard of protection <0.5%
0 Maintain current defences with replacement, refurbishment and general repairs as required
PCC/MoD MOD ongoing
Surface
Surface water management plan area
Overlap with other wards
Background informationProperties presently at risk (1% annual probability rain event) Historic flood
recordsProposed measures Project lead
Completion date
Residential Commercial
none n/a EA AStSWF map shows railway line acts as a bund trapping water. Very little evidence to support this
0 0 Sparse Low surface water flood risk. Potential for high velocity overland flows due to hill topography
n/a n/a
Groundwater
Groundwater desktop study targeted area
Overlap with other wards
Background information Proposed measures Project leadCompletion date
11 – Cosham and Paulsgrove
Cosham Highlighted as susceptible to groundwater emergence due to a geological permeability boundary
Gather information relating to groundwater levels, contaminants, sewer infiltration, sea defence integrity and ground infiltration rates, for sharing among partner organisations, internally to PCC and property developers. Will result in a groundwater trend report for the city of Portsmouth
PCC with support requested from Environment Agency, Southern Water, PCC planning department, Eastern Solent Coastal Partnership
2020
38 • Local flood risk management strategy • Cosham
1
11
10
CoshamCosham ward is dominated by the south side of Portsdown Hill and the railway line dissects the area. There are large open spaces towards the top of the hill, King George playing fields and the Lakeside commercial development.
The coastline runs along the south side embankment of the M27 and is wholly on the north side of Portscreek which separates the mainland from Portsea Island and connects Langstone and Portsmouth Harbours.
Flooding
Cosham has a number of separate surface water drainage networks along with a number of combined drainage networks. There are some localised records of surface water flooding, most of which are caused by localised issues like blocked gullies or overland flows from the hill.
There have been very few historical incidents of wave overtopping along the M27 frontage which acts as a barrier. The area to the south of the railway line has been identified for targeted groundwater investigation. There is potential for tide-locking to occur, however there are very few instances where this is thought to have contributed to flooding.
This area features in the recently approved Portchester Castle to Emsworth Coastal Strategy – actions are outlined on the next page.
Key
PEMS flood cell 3
Ward boundary
areas targeted for groundwater investigation
SWMP hotspots
A localised surface water flood event in Cosham ward
Cosham • Local flood risk management strategy • 39
Coastal
AreaOverlap with other wards
Sea defence type(s)
Background informationResidential properties at risk (0.5% annual probability flood event)
Proposed measures* (target standard of protection <0.1%)
Responsible authority
FundingCompletion date
(Part of) M27 and Farlington (Reach 3)
Drayton and Farlington
Concrete block revetment
M27 frontage provides protection to strategic infrastructure of M27/A27 and the South Coast railway. Refurbishment works recently completed by the Highways Agency means the condition of the revetment here is currently good. Current standard of protection <0.1%
1863 Maintenance of M27 revetment HA HA Ongoing
*Refer also to measures required for overlapping wards due to interdependency of flood cells
Surface
Surface water management plan area
Overlap with other wards
Background informationProperties presently at risk (1% annual probability rain event) Historic flood
recordsProposed measures Project lead
Completion date
Residential Commercial
1 – Cosham
Drayton and Farlington
EA mapping shows railway line acts as a bund trapping water. Very little evidence to support this. A recent flood event in this area is not thought to have been influenced by the railway line
481 90 Sparse Area considered too large to treat as one group. Further investigation needed
PCC ongoing
Groundwater
Groundwater desktop study targeted area
Overlap with other wards
Background information Proposed measures Project leadCompletion date
11 – Cosham and Paulsgrove
Paulsgrove Highlighted as susceptible to groundwater emergence due to a geological permeability boundary
Gather information relating to groundwater levels, contaminants, sewer infiltration, sea defence integrity and ground infiltration rates, for sharing among partner organisations, internally to PCC and property developers. Will result in a groundwater trend report for the city of Portsmouth
PCC with support requested from Environment Agency, Southern Water, PCC planning department, Eastern Solent Coastal Partnership
2020
40 • Local flood risk management strategy • Drayton and Farlington
Drayton and FarlingtonDrayton and Farlington ward is dominated by the south side of Portsdown Hill and Farlington Marshes to the south. There are large open spaces towards the top of the hill in the area of the underground reservoirs and Farlington Marshes itself, which is dissected by the A27. The developed area is largely to the north of the railway line which runs along the north side of the marshes. The coastline runs partly along the south side embankment of the M27 and around Farlington Marshes and is partly on the north side of Portscreek and partly Langstone Harbour.
Flooding
The ward has a number of separate surface water drainage networks along with a number of combined drainage networks. There have been a number of recent flooding events which affected some residential properties and these have been well documented.
There have been very few historical incidents of wave overtopping along the M27 frontage, while the marshes are allowed to flood at high tide events due to their importance for rare bird species.
The area around the north of Farlington Marshes has been identified for targeted groundwater investigation.
It is likely that a combination of factors contributed to the three recent flood events at the same location in the ward, including groundwater, tidal influence, rainfall and inability for the sewerage system to cope. Investigations by PCC and Southern Water are ongoing.
This area features in the recently approved Portchester Castle to Emsworth Coastal Strategy – actions are outlined overleaf. Work on the Farlington Marshes coastal defences are ongoing with the Environment Agency and the Eastern Solent Coastal Partnership on behalf of PCC.
Key PEMS flood cell 3
Ward boundary
areas targeted for groundwater investigation
SWMP hotspots
A recent flood event in Drayton and Farlington ward
1
2
1110
Drayton and Farlington • Local flood risk management strategy • 41
Coastal
AreaOverlap with other wards
Sea defence type(s)
Background informationResidential properties at risk
Proposed measures (target standard of protection <0.1% at M27; 20% for 20 years at Farlington)
Responsible authority
FundingCompletion date
(Part of) M27 and Farlington (Reach 3)
Drayton and Farlington
Concrete block revetment
M27 frontage provides protection to strategic infrastructure of M27/A27 and the railway. Refurbishment works mean the condition of the revetment is good. Current standard of protection <0.1%. Farlington frontage provides protection to the Farlington Marshes SPA. Defence condition is poor – regular overtopping occurs, and repair/maintenance required annually. Standard of protection 20%
1449 Maintenance of M27 revetment HA HA Ongoing
Maintenance of Farlington Marshes revetment EA in the short term
EA Ongoing
Provision of vehicle underpass flood gate and culvert flaps beneath A27 at Farlington Marshes
PCC/EA/HWT
Flood Defence Grant in Aid secured
Completed
Undertake Solent-wide study to identify economic, environmental and social impacts of either improving existing revetment at Farlington Marshes, or undertaking managed realignment
EA/PCC/HA High probability of attracting Flood Defence Grant in Aid
Required by 2020
Surface
Surface water management plan area
Overlap with other wards
Background informationProperties presently at risk (1% annual probability rain event)
Historic flood records
Proposed measuresProject lead
Completion date
Residential Commercial
1 – Cosham
Cosham EA mapping shows railway line acts as a bund trapping water. Very little evidence to support this. A recent flood event in this area is not thought to have been influenced by the railway line
481 90 Sparse Area considered too large to treat as one group. Further investigation needed
PCC ongoing
2 – Farlington Marshes
n/a The marshes act as a drain to a number of properties in the Drayton and Farlington areas. Ditch clearance work undertaken October 2014. Further ditch clearance work proposed for winter 2015/16
0 4 Sparse Clearance of surface water pathways. Environmental designations and the importance of the marshes as a wetland habitat for bird species may restrict work
PCC/EA Partially completed
To complete Oct 2015
Station Road (not in SWMP)
n/a Three separate flood incidents in the winter of 2012/13. Extends to over 50 properties. Manhole surcharge witnessed on each occasion. Exact cause not yet known
50 0 Very good
PCC and Southern Water are investigating the cause with a view to providing a long term solution. Temporary pumps are in place until permanent pumps are planned to be installed in 2015
PCC/ Southern Water
ongoing
Total 531 94
Groundwater
Groundwater desktop study targeted area
Overlap with other wards
Background information Proposed measures Project leadCompletion date
10 – Farlington (excluding marshes south of A27)
n/a Low topography, likely to have high groundwater table. Highlighted as susceptible to groundwater emergence due to a geological permeability boundary
Gather information relating to groundwater levels, contaminants, sewer infiltration, sea defence integrity and ground infiltration rates, for sharing among partner organisations, internally to PCC and property developers. Will result in a groundwater trend report for the city of Portsmouth
PCC with support requested from Environment Agency, Southern Water, PCC planning department, Eastern Solent Coastal Partnership
2020
A recent flood event in Drayton and Farlington ward
42 • Local flood risk management strategy • Hilsea
HilseaHilsea ward is located in the northwest corner of Portsea Island and is predominantly of low topography. There are large open spaces in the form of Alexandra Park, various playing fields and around the Hilsea Lines scheduled ancient monument.
The developed area is largely set back from the coast. The coastline runs from the Mountbatten Centre on Tipner Lake to the railway bridge on the south side of Portscreek.
Flooding
Hilsea ward has a number of separate surface water drainage networks along with some combined and a small number of privately owned drainage networks. There have been very few historical incidents of wave overtopping along the frontage which is well sheltered by the motorway embankments of the M27 and M275.
Hilsea ward forms part of two separate areas identified for targeted groundwater investigation.
There have been a number of recent flooding events which affected some private properties externally and these have been well documented. It is likely that a number of factors have contributed to the flooding including defective sewer systems, groundwater, impermeable ground, rainfall and tide-locking. PCC and Southern Water are working together to investigate and take corrective actions.
This area features in the Portsea Island Coastal Strategy Study – actions are outlined on the next page.
Wave overtopping at Alexandra Park
Key PEMS flood cell 3
PICSS flood cell 4
Ward boundary
areas targeted for groundwater investigation
SWMP hotspots
4k
4l
3
65
10
8
7
11
6
Hilsea • Local flood risk management strategy • 43
Coastal
AreaOverlap with other wards
Sea defence type(s)
Background information
Residential properties at risk (0.5% annual probability flood)
Proposed measures (target standard of protection 0.5%)
Responsible authority
FundingCompletion date
Portscreek South (4k)
Copnor Seawalls, revetments
Frontage provides protection to commercial and residential properties, and Hilsea Lines scheduled ancient monument. Existing standard of protection 10%
1704 Raise existing embankment and maintain existing walls and revetments
PCC Flood Defence Grant in Aid
2015/16
Hilsea Lido to Tipner Lake (4l)
n/a Seawalls, revetments
Frontage provides protection primarily to residential properties. Existing standard of protection 10%
Replace existing structures with higher levels to provide a sustained standard of flood protection against sea level rise
PCC Flood Defence Grant in Aid
2025/26
(Part of) M27 and Farlington (Reach 3)
Drayton and Farlington
Concrete block revetment
M27 frontage provides protection to strategic infrastructure of M27/A27 and the South Coast railway. Refurbishment works recently completed by Highways Agency means condition of revetment here is currently good. Current standard of protection <0.1%
1863 Maintenance of M27 revetment HA HA Ongoing
Surface
Surface water management plan area
Overlap with other wards
Background informationProperties presently at risk (1% annual probability rain event) Historic flood
recordsProposed measures Project lead
Completion date
Residential Commercial
3 – War department sewer
Copnor Exact location and function of 1920s sewer is unclear
0 5 Sparse Further investigation required PCC/Southern Water
ongoing
5 – Northern Parade (Alex Way area)
n/a This area is a natural low point and the first point of emergence of flood waters when the sewer system is at capacity. Regular flooding to residents’ garages
0 4 Very good Clearance of blockages in the sewer network undertaken by Southern Water. Responsibility for the private sewer has for the meantime been taken on by PCC/Colas for maintenance purposes
PCC/Southern Water
completed
Groundwater
Groundwater desktop study targeted area
Overlap with other wards
Background information Proposed measures Project leadCompletion date
7 – Hilsea n/a Highlighted as susceptible to groundwater emergence due to a geological permeability boundary
Gather information relating to groundwater levels, contaminants, sewer infiltration, sea defence integrity and ground infiltration rates, for sharing among partner organisations, internally to PCC and property developers. Will result in a groundwater trend report for the city of Portsmouth
PCC with support requested from Environment Agency, Southern Water, PCC planning department, Eastern Solent Coastal Partnership
2020
8 – Alexandra Park and Tipner
Nelson Highlighted as susceptible to groundwater emergence due to a geological permeability boundary
PCC with support requested from Environment Agency, Southern Water, PCC planning department, Eastern Solent Coastal Partnership
2020
44 • Local flood risk management strategy • Copnor
CopnorCopnor ward is located on the northeast corner of Portsea Island. There are large open spaces on the northern part of Great Salterns golf course, various playing fields and a part of Hilsea Lines scheduled ancient monument. The developed area is largely set back from the coast and is dominated by the railway line, industrial estates and Anchorage Park housing estate. The coastline runs from the railway bridge on the south side of Portscreek to the Harvester on the Eastern Road.
Flooding
Copnor ward has a small number of separate surface water drainage networks but is dominated by combined drainage networks. There have been very few historical incidents of wave overtopping along the frontage which is sheltered by Eastern Road.
Copnor ward forms part of two separate areas identified for targeted groundwater investigation.
There have been a number of historic flood events which affected some private property and a main road. It is likely that this is caused by a fault in the local sewerage network, which Southern Water are currently rectifying.
This area features in the Portsea Island Coastal Strategy Study – actions are outlined on the next page.
4k
4j
4l
3
4
6
9
7
8
6
5
Key
PICSS flood cell 4
Ward boundary
areas targeted for groundwater investigation
SWMP hotspots
Copnor Road affected by surface water
Copnor • Local flood risk management strategy • 45
Coastal
AreaOverlap with other wards
Sea defence type(s)
Background information
Residential properties presently at risk (0.5% annual probability flood)
Proposed measures (target standard of protection 0.5%)
Responsible authority
FundingCompletion date
Portscreek South (4k)
Hilsea Seawalls, revetments
Frontage protects to commercial and residential properties, and Hilsea Lines scheduled ancient monument. Existing standard of protection 10%
837 Raise embankment and maintain existing walls and revetments
PCC Flood Defence Grant in Aid
2015/16
Eastern Road Bridge to Great Salterns Quay (4j)
n/a Seawalls, revetments
Frontage protects to A2030, golf course, housing estate and some commercial properties. Existing standard of protection 0.5%
Strengthen existing walls and raise defences to provide a sustained standard of protection accounting for sea level rise
PCC Flood Defence Grant in Aid
2025/26
Surface
Surface water management plan area
Overlap with other wards
Background informationProperties presently at risk (1% annual probability rain event)
Historic flood records
Proposed measures Project leadCompletion date
Residential Commercial
3 – War department sewer
Hilsea Exact location and function of 1920s sewer is unclear
0 5 Sparse Further investigation required. PCC/Southern Water
ongoing
4 – Anchorage Park n/a High surface water flood risk due to low topography and combined drainage system
34 6 Sparse PCC monitoring situation PCC ongoing
6 – Copnor Road (Amberley Road area)
Hilsea Flooding to main A288 Copnor Road, rendering impassable
7 4 Good Copnor Road Scheme – new piped network and pumping station
Southern Water
completed
7 – Quartremaine Industrial Estate
n/a High flood risk as a large part of northern Portsea Island drains through the area
0 4 Sparse Quartremaine Road Scheme – changes to infrastructure and new box culvert
Southern Water
completed
8 – Great Salterns golf course
Baffins Golf course regularly floods when EA main river running through the centre of the course bursts its banks
1 11 Good Great Salterns Scheme – additional storm water channel, culvert and upgrade of existing pumping station
Southern Water
completed
9 – Copnor Road (Monckton Road area)
n/a Flooding in localised topographical low spot
36 8 Good Kiln Road Scheme addressing the issues. Includes a new pumping station
Southern Water
completed
Total 78 38
Groundwater
AreaOverlap with other wards
Background information Proposed measures Project leadCompletion date
5 – Great Salterns Baffins Low topography, likely to have high groundwater table. Highlighted as susceptible to groundwater emergence due to a geological permeability boundary
Gather information relating to groundwater levels, contaminants, sewer infiltration, sea defence integrity and ground infiltration rates, for sharing among partner organisations, internally to PCC and property developers. Will result in a groundwater trend report for the city of Portsmouth
PCC with support requested from Environment Agency, Southern Water, PCC planning department, Eastern Solent Coastal Partnership
2020
6 – Anchorage Park n/a
46 • Local flood risk management strategy • Nelson
NelsonNelson ward is located on the western side of Portsea Island and is predominantly of low topography. There are large open spaces in the form of Stamshaw Park, the MoD rifle range and the ferry ports. The ward includes Tipner, Whale Island and the commercial ferry port.
The developed area is largely set back from the coast to the east of the M275 motorway. The coastline runs from the Mountbatten Centre on Tipner Lake to Flathouse Quay which are on Portsmouth Harbour frontage.
Flooding
Nelson ward has an extensive network of separate surface water drainage as well as some combined drainage networks.
There have been very few historical incidents of tidal flooding to properties which are well sheltered by the motorway embankment of the M275.
Nelson ward has been identified for targeted groundwater investigation along the coastal side.
There have been a number of historic surface water flood events in small pockets across the ward. It is thought that inadequacies in the localised sewerage system have contributed. These are presently being addressed by Southern Water and flooding has not occurred recently in the areas where it was previously an issue.
This area features in the Portsea Island Coastal Strategy Study – actions are outlined on the next page.
A typical localised flood event which has not occurred recently
Key PICSS flood cell 4
Ward boundary
areas targeted for groundwater investigation
SWMP hotspots
6n
6p
6o
5m
10
8
9
Nelson • Local flood risk management strategy • 47
Coastal
AreaOverlap with other wards
Sea defence type(s)
Background information
Residential properties presently at risk (0.5% annual probability flood)
Proposed measures (target standard of protection falls from 10% for Tipner as sea levels rise)
Responsible authority
FundingCompletion date
Tipner Lake to Rotten Row (5m)
n/a Seawalls, revetments
Frontage provides protection to some residential properties, a school and MoD rifle range. Statutory requirement to maintain the coastal defences to minimise the risk of any potential contaminates entering Portsmouth Harbour’s water body. Portsmouth Harbour is designated SAC, SPA, Ramsar and SSSi under the Habitats Regulations. Improvements to the coastal defences will be necessary, if the site is redeveloped, to manage the long term flood risk. Existing standard of protection 10%
32 Repair existing seawall and re-profile flood embankment to secure contaminated land. If the site is regenerated, developers will replace and improve defences
Further flood protection measures around Tipner may occur as part of the City Deal funding
PCC/MoD/developer
Uncertain Works to secure contaminated land required by 2018
Rotten Row to Albert Johnson Quay (6n)
n/a Seawalls, revetments
Frontage provides protection to M275, some commercial properties and the commercial ferryport. Existing standard of protection 2-10%
Monitor and maintain existing defences as required
Landowner/PCC
Contribu-tions required
Ongoing
Surface
Surface water management plan area
Overlap with other wards
Background informationProperties presently at risk (1% annual probability rain event) Historic flood
recordsProposed measures Project lead
Completion date
Residential Commercial
10 – Stamshaw Hilsea Flooding to a group of houses in the local area
116 2 Sparse Southern Water Gruneisen Road pumping station replacement complete
Southern Water
completed
Groundwater
Groundwater desktop study targeted area
Overlap with other wards
Background information Proposed measures Project leadCompletion date
8 – Alexandra Park and Tipner
Nelson Highlighted as susceptible to groundwater emergence due to a geological permeability boundary
Gather information relating to groundwater levels, contaminants, sewer infiltration, sea defence integrity and ground infiltration rates, for sharing among partner organisations, internally to PCC and property developers. Will result in a groundwater trend report for the city of Portsmouth
PCC with support requested from Environment Agency, Southern Water, PCC planning department, Eastern Solent Coastal Partnership
2020
9 – Stamshaw n/a Highlighted as susceptible to groundwater emergence due to a geological permeability boundary
PCC with support requested from Environment Agency, Southern Water, PCC planning department, Eastern Solent Coastal Partnership
2020
48 • Local flood risk management strategy • Baffins
BaffinsBaffins ward is located on the eastern side of Portsea Island and is predominantly of low topography. There are large open spaces in the form of the southern side of Great Salterns golf course, Milton Common, allotments and various other green spaces. The developed area is largely set back from the coast to the west of the Eastern Road. The coastline runs from the Harvester to Milton Common on Langstone Harbour frontage. The ward also includes Great Salterns Lake which acts as the main surface water drainage outlet for approximately one quarter of Portsea Island. The lake and its tributary culvert feeding into it from the golf course to the north are designated as a main river. It has pumps which trigger at a certain water level in times of high tide.
Flooding
Baffins ward has a number of separate surface water drainage networks but is largely served by combined drainage networks. Baffins ward forms part of two separate areas identified for targeted groundwater investigation.
There are a few pockets of surface water flooding recorded, and there have been incidents of wave overtopping along the Eastern Road frontage which causes disruption to one of the arterial roads of Portsmouth. It is highly likely that there was groundwater influence on one of the more recent events.
This area features in the Portsea Island Coastal Strategy Study – actions are outlined on the next page.
Key
PICSS flood cell 4
Ward boundary
areas targeted for groundwater investigation
SWMP hotspots
Wave overtopping along Eastern Road frontage in January 2015
4j
4i
3h
8
5
4
Baffins • Local flood risk management strategy • 49
Coastal
AreaOverlap with other wards
Sea defence type(s)
Background information
Residential properties presently at risk (0.5% annual probability flood)
Proposed measures (target standard of protection 0.5%)
Responsible authority
FundingCompletion date
Milton Bund to Tangier Road seawall (4i)
n/a Seawalls, revetments, embankments
Frontage protects to residential properties and Milton Common (former landfill site). Existing standard of protection 0.5%)
23 Raise crest wall and embankment, provide shoreline protection
PCC Flood Defence Grant in Aid
Phased from 2015/16 to 2025/26Eastern Road
bridge to Great Salterns Quay (4j)
Copnor Seawalls, revetments
Frontage protects to A2030, golf course, housing estate and some commercial properties. Existing standard of protection 0.5%.
Strengthen existing walls and raise defences to provide a sustained standard of protection accounting for sea level rise
PCC Flood Defence Grant in Aid
Surface
Surface water management plan area
Overlap with other wards
Background informationProperties presently at risk (1% annual probability rain event)
Historic flood records
Proposed measures Project leadCompletion date
Residential Commercial
8 – Great Salterns golf course
n/a Golf course regularly floods when EA main river running through the centre of the course bursts its banks
1 11 Good Additional storm water channel, additional culvert and upgrade of existing pumping station
Southern Water
completed
Tangier Road (not in SWMP)
n/a Southern Water have identified a scheme to remove surface water from the combined sewer network
n/a n/a Some New piped network and outfall to Great Salterns Lake
Southern Water
completed
Total 1 11
Groundwater
Groundwater desktop study targeted area
Overlap with other wards
Background information Proposed measures Project leadCompletion date
5 – Great Salterns
Copnor Low topography, likely to have high groundwater table. Highlighted as susceptible to groundwater emergence due to a geological permeability boundary
Gather information relating to groundwater levels, contaminants, sewer infiltration, sea defence integrity and ground infiltration rates, for sharing among partner organisations, internally to PCC and property developers. Will result in a groundwater trend report for the city of Portsmouth
PCC with support requested from Environment Agency, Southern Water, PCC planning department, Eastern Solent Coastal Partnership
end 2014
4 – Milton Milton Low topography, likely to have high groundwater table. Highlighted as susceptible to groundwater emergence due to a geological permeability boundary
PCC with support requested from Environment Agency, Southern Water, PCC planning department, Eastern Solent Coastal Partnership
end 2014
Stanley Avenue n/a Flooding to garages along the rear access road. Investigations have found that the likely source is groundwater with 95% surety.
Burehole installed to monitor GW levels PCC with support from Souther Water Investigations
2020
50 • Local flood risk management strategy • Fratton
FrattonFratton ward is located in the centre of Portsea Island and has no coastline. There are open spaces in the form of Kingston Cemetery, various parks and school playing fields. The developed area is predominantly residential with a few commercial districts.
A large proportion of the ward has impermeable areas, meaning most of the rainfall falls on hard ground (roads, tarmac, paving, roofs) and runs along the surface until it can find a way into the sewers.
Flooding
Fratton ward has a predominantly combined drainage network.
There are a few pockets of surface water flooding recorded, but these are very localised and are most likely caused by blocked gullies or pipes.
There is limited tidal or groundwater influence, the ward is highly dependant on the sewerage network.
Fratton ward has not been identified for targeted groundwater investigation.
Key
Ward boundary areas targeted for groundwater investigation
A localised highway flood, typical of Fratton ward.
9
5
Fratton • Local flood risk management strategy • 51
Surface
Surface water management plan area
Overlap with other wards
Background informationProperties presently at risk (1% annual probability rain event)
Historic flood records
Proposed measures Project leadCompletion date
Residential Commercial
none n/a Fratton ward has not been identified for surface water investigation
0 0 Sparse none at present n/a n/a
If you would like to report a flood:There are a number of processes in place by which you can report a flood, or issues with the drainage system like blocked gullies:
• To report an issue with gullies anywhere in the city complete the form by visiting www.portsmouth.gov.uk and search for ‘report it gullies’. You will need to supply an accurate address to allow us to find the gully and short description of the problem.
• Direct to the council’s Drainage Team at [email protected] or phone 023 9284 1588 which will be picked up by a PCC Drainage Officer.
• If you believe a flood contains wastewater, PCC advises that you contact Southern Water directly, by filling out an enquiry form at www.southernwater.co.uk and search for ‘wastewater enquiries’ or phone 0845 278 0845. PCC does not have the power to work on sewers or structures owned by third parties or other Risk Management Authorities, but we do work together to resolve issues.
• PCC City Help Desk 023 9283 4092.
• Colas 023 9231 0900. Many local issues, where appropriate, are passed to Colas by PCC to investigate under the terms of the Private Finance Initiative (PFI) agreement, which is in place until 2029. In normal circumstances reported issues are investigated and actioned within 28 days but in reality it is highly likely to be much quicker. You may wish to call them directly.
• For social housing, we recommend you contact your area housing office in the first instance. Visit www.portsmouth.gov.uk and search for area housing office.
• IN AN EMERGENCY, CALL 999 IF YOU ARE IN DANGER OR PEOPLE HAVE BEEN INJURED.
52 • Local flood risk management strategy • Charles Dickens
Charles DickensCharles Dickens ward is located on the western side of Portsea Island and includes the main shopping area of Commercial Road, HM Naval Base and the Historic Dockyard. There are limited open spaces although it does include Victoria Park and The Hard.
The developed area is largely set back from the coast due to the location of HM Naval Base. The coastline runs from Flathouse Quay to The Hard which are on Portsmouth Harbour frontage.
Flooding
Charles Dickens ward has a predominantly combined drainage network although there are a number of surface water and private sewers.
There are a few pockets of surface water flooding recorded, but these are very localised and are most likely caused by blocked gullies or pipes.
The area is susceptible to tidal and groundwater influences to flooding during a rain event.
Charles Dickens ward forms part of an area targeted for groundwater investigation.
This area features in the Portsea Island Coastal Strategy Study – actions are outlined on the next page.
Key PICSS flood cell 6
PICSS flood cell 7
Ward boundary
areas targeted for groundwater investigation
SWMP hotspots
Anglesea Road affected by surface water flooding1a
7q
6n
6p
11
9
1
Charles Dickens • Local flood risk management strategy • 53
Coastal
AreaOverlap with other wards
Sea defence type(s)
Background information
Residential properties presently at risk (0.5% annual probability flood)
Proposed measures (target standard of protection 0.5%)
Responsible authority
FundingCompletion date
Flathouse Quay to The Hard (7q)
n/a Seawalls, revetments
Frontage provides protection to HM Naval Base, some commercial and residential properties. Existing standard of protection generally 0.5%
0 Repair or replace seawalls as required to a higher level to keep pace with sea level rise
MoD/PCC Alternative sources of funding may be required to secure the money required to implement these works, including from the MoD
post 2021
Surface
Surface water management plan area
Overlap with other wards
Background informationProperties presently at risk (1% annual probability rain event)
Historic flood records
Proposed measures Project leadCompletion date
Residential Commercial
11 – Ordnance Row
n/a Flooding to a cluster of properties 30 18 Sparse Southern Water sewer works have reduced the frequency of flooding
Southern Water
Completed
Groundwater
Groundwater desktop study targeted area
Overlap with other wards
Background information Proposed measures Project leadCompletion date
1 – City Centre St Thomas Highlighted as susceptible to groundwater emergence due to a geological permeability boundary
Gather information relating to groundwater levels, contaminants, sewer infiltration, sea defence integrity and ground infiltration rates, for sharing among partner organisations, internally to PCC and property developers. Will result in a groundwater trend report for the city of Portsmouth
PCC with support requested from Environment Agency, Southern Water, PCC planning department, Eastern Solent Coastal Partnership
2020
54 • Local flood risk management strategy • Milton
MiltonMilton ward is located on the eastern side of Portsea Island and is predominantly of low topography. There are large open spaces in the form of Bransbury Park, St Mary’s and St James hospitals, Fratton Park football ground, allotments and various other green spaces.
The developed area is largely set back from the coast. The coastline runs from Milton Common to the western edge of Eastney Lake on Langstone Harbour frontage.
Flooding
Milton ward has a combination of combined, surface water and private drainage networks.
There are a few pockets of surface water flooding recorded, but these are very localised and are most likely caused by blocked gullies or pipes.
There are sparse records of tidal flooding. There is potential for groundwater and tidal water to influence flooding.
Milton ward forms part of two areas targeted for groundwater investigation.
This area features in the Portsea Island Coastal Strategy Study – actions are outlined on the next page. An options appraisal for the coastline is to commence in summer 2014.
Key PICSS flood cell 3
PICSS flood cell 4
Ward boundary
areas targeted for groundwater investigation
SWMP hotspots
The seawall and frontage at the Thatched House
4i
2g
2e
4
3
Milton • Local flood risk management strategy • 55
Coastal
AreaOverlap with other wards
Sea defence type(s)
Background information
Residential properties presently at risk (0.5% annual probability flood)
Proposed measures (target standard of protection 0.5%)
Responsible authority
Funding Completion date
Milton Bund to Tangier Road seawall (4i)
n/a Seawalls, revetments, embankments
Frontage provides protection to residential properties and Milton Common (former landfill site). Existing standard of protection 0.5%)
23 Raise crest wall and embankment, provide shoreline protection
PCC Flood Defence Grant in Aid
Phased from 2015/16 to 2025/26
Eastney Lake to Thatched House PH seawall (3h)
n/a Seawalls Frontage provides protection to residential and commercial properties. Existing standard of protection 0.5%
Maintain and monitor defences Landowner/PCC
Landowner 2021/22
Surface
Surface water management plan area
Overlap with other wards
Background informationProperties presently at risk (1% annual probability rain event)
Historic flood records
Proposed measures Project leadCompletion date
Residential Commercial
none n/a Milton ward has not been identified for surface water investigation
0 0 Sparse none at present n/a n/a
Groundwater
Groundwater desktop study targeted area
Overlap with other wards
Background information Proposed measures Project leadCompletion date
3 – Eastney Eastney and Craneswater
Highlighted as susceptible to groundwater emergence due to a geological permeability boundary
Gather information relating to groundwater levels, contaminants, sewer infiltration, sea defence integrity and ground infiltration rates, for sharing among partner organisations, internally to PCC and property developers. Will result in a groundwater trend report for the city of Portsmouth
PCC with support requested from Environment Agency, Southern Water, PCC planning department, Eastern Solent Coastal Partnership
2020
4 – Milton Baffins Highlighted as susceptible to groundwater emergence due to a geological permeability boundary
PCC with support requested from Environment Agency, Southern Water, PCC planning department, Eastern Solent Coastal Partnership
2020
56 • Local flood risk management strategy • St Thomas
St ThomasSt Thomas ward is located on the southwestern side of Portsea Island and includes Gunwharf Quays shopping development. There are limited open spaces although it does include part of Southsea Common, HMS Temeraire naval sports facility and Ravelin Park. Residential developed areas are largely set back from the coast except in the Old Portsmouth area.
The coastline runs from The Hard to Clarence Pier which are on Portsmouth Harbour’s entrance and the Solent.
Flooding
St Thomas ward has a good surface water network with some combined sewers. There are a few pockets of surface water flooding recorded, but these are very localised and are most likely caused by blocked gullies or pipes.
There are good records of coastal flooding to properties, especially in the Old Portsmouth area.
There is a high likelihood of groundwater levels influencing flooding. Old Portsmouth was, until recently, known to have significant seawater infiltration to the trunk sewers. Southern Water have now undertaken renovation of the sewer network to minimise the amount of seawater infiltration. St Thomas ward forms part of an area targeted for groundwater investigation.
Old Portsmouth has a network of over 30 tidal flood floodgates which raise the standard of protection to 0.5% AEP (in 2006). The Eastern Solent Coastal Partnership is responsible for overseeing the operation and maintenance of the gates during high tide windows. A response is triggered by a messaging service from the Environment Agency.
This area features in the Portsea Island Coastal Strategy Study – actions are outlined on the next page.
Old Portsmouth floodgates during a high tide flood event
Key PICSS flood cell 1
PICSS flood cell 7
Ward boundary
areas targeted for groundwater investigation
SWMP hotspots
1b
1a 13
12
11
2
1
St Thomas • Local flood risk management strategy • 57
Coastal
AreaOverlap with other wards
Sea defence type(s)
Background information
Residential properties presently at risk (0.5% annual probability flood)
Proposed measures (target standard of protection 0.5%)
Responsible authority
FundingCompletion date
Spur Redoubt to Blue Reef Aquarium (1b)
St Jude Seawall, revetments, groynes, other
Frontage provides protection to residential and commercial properties and scheduled ancient monuments. Existing standard of protection varies between 10-100%
533 Raise seawalls where possible along landward edge of promenade, strengthen foreshore in areas that rapidly lose beach material during storms and result in damage to promenade (Clarence Esplanade additional rock toe protection). Final set of measures employed will be consistent with Seafront Masterplan
Phase 1 2020/21
Phase 2 2025/26
Flood Defence Grant in Aid
2018/19
Old Portsmouth (1a)
n/a Seawalls, revetments, other
Frontage provides protection to residential and commercial properties and scheduled ancient monuments. Existing standard of protection 0.5%
No works planned – defences recently improved
Strategy review for Old Portsmouth currently being undertaken
PCC n/a To be identified by review
Surface
Surface water management plan area
Overlap with other wards
Background informationProperties presently at risk (1% annual probability rain event)
Historic flood records
Proposed measures Project leadCompletion date
Residential Commercial
12 – Hambrook Street
n/a Flooding to a cluster of properties in 2009 9 2 Sparse PCC is monitoring the situation. There may be a spring in the area which contributes
PCC ongoing
Groundwater
Groundwater desktop study targeted area
Overlap with other wards
Background information Proposed measures Project leadCompletion date
1 – City Centre Charles Dickens
Highlighted as susceptible to groundwater emergence due to a geological permeability boundary
Gather information relating to groundwater levels, contaminants, sewer infiltration, sea defence integrity and ground infiltration rates, for sharing among partner organisations, internally to PCC and property developers. Will result in a groundwater trend report for the city of Portsmouth
PCC with support requested from Environment Agency, Southern Water, PCC planning department, Eastern Solent Coastal Partnership
2020
58 • Local flood risk management strategy • Central Southsea
Central SouthseaCentral Southsea ward is located in the central southern area of Portsea Island and has no coastline. There are very limited open spaces. The developed area is predominantly residential with a few shopping districts.
A large proportion of the district has impermeable areas, meaning most of the rainfall falls on hard ground and runs along the surface until it can find a way into the sewers.
Flooding
Central Southsea ward has a predominantly combined sewer network.
There are a few pockets of surface water flooding recorded, but these are very localised and are most likely caused by blocked gullies or pipes.
There is limited tidal or groundwater influence, the ward is highly dependant on the sewerage network.
Central Southsea ward has not been targeted for groundwater investigation.
Key
Ward boundary
areas targeted for groundwater investigation
SWMP hotspots
An example of the type of surface water flood in Central Southsea ward
2
1
Central Southsea • Local flood risk management strategy • 59
Surface
Surface water management plan area
Overlap with other wards
Background informationProperties presently at risk (1% annual probability rain event)
Historic flood records
Proposed measures Project leadCompletion date
Residential Commercial
none n/a Central Southsea ward has not been identified for surface water investigation
0 0 Sparse none at present n/a n/a
If you would like to report a flood:There are a number of processes in place by which you can report a flood, or issues with the drainage system like blocked gullies:
• To report an issue with gullies anywhere in the city complete the form by visiting www.portsmouth.gov.uk and search for ‘report it gullies’. You will need to supply an accurate address to allow us to find the gully and short description of the problem.
• Direct to the council’s Drainage Team at [email protected] or phone 023 9284 1588 which will be picked up by a PCC Drainage Officer.
• If you believe a flood contains wastewater, PCC advises that you contact Southern Water directly, by filling out an enquiry form at www.southernwater.co.uk and search for ‘wastewater enquiries’ or phone 0845 278 0845. PCC does not have the power to work on sewers or structures owned by third parties or other Risk Management Authorities, but we do work together to resolve issues.
• PCC City Help Desk 023 9283 4092.
• Colas 023 9231 0900. Many local issues, where appropriate, are passed to Colas by PCC to investigate under the terms of the Private Finance Initiative (PFI) agreement, which is in place until 2029. In normal circumstances reported issues are investigated and actioned within 28 days but in reality it is highly likely to be much quicker. You may wish to call them directly.
• For social housing, we recommend you contact your area housing office in the first instance. Visit www.portsmouth.gov.uk and search for area housing office.
• IN AN EMERGENCY, CALL 999 IF YOU ARE IN DANGER OR PEOPLE HAVE BEEN INJURED.
60 • Local flood risk management strategy • St Jude
St JudeSt Jude ward is located on the south coast of Portsea Island and includes highly residential areas and some commercial districts and ancient monuments. There are some open spaces including Southsea Common and Clarendon Gardens.
Residential developed areas are largely set back from the coast. The coastline of St Jude runs from Clarence Pier to Burgoyne Road and is directly facing onto the Solent. The Seafront Masterplan outlines proposals to improve the amenity value of the promenade.
Flooding
St Jude ward has a largely combined sewer network.
The ward was badly affected in 2000 by flooding, which is well documented. It is likely that the low topography of the Great Morass and Little Morass areas was a factor. Other factors include groundwater, tide-locking and sewerage network issues.
There are sparse records of coastal flooding.
St Jude ward forms part of a large area targeted for groundwater investigation.
This area features in the Portsea Island Coastal Strategy Study – actions are outlined on the next page.
Key
PICSS flood cell 1
Ward boundary
areas targeted for groundwater investigation
SWMP hotspots
Submerged cars during the September 2000 flood event1c
1b
14
13
2
1
Eastney and Craneswater • Local flood risk management strategy • 61
Coastal
AreaOverlap with other wards
Sea defence type(s)
Background information
Residential properties presently at risk (0.5% annual probability flood)
Residual Life of existing defences
Proposed measures (target standard of protection 0.5%)
Responsible authority
Completion date
1b – Spur Redoubt to Blue Reef Aquarium
St Thomas Seawall, revetments, groynes, other
Frontage provides protection to Southsea Common, residential and commercial areas and scheduled ancient monuments
3310 10-15 years except 5-10 years (Clarence Esplanade and Clarence Pier)
Reduce tidal flood risk from (existing) 5% AEP to 0.5% AEP by improving coastal defences. Construct new wave return and splash walls, demountable defences
PCC Phase 1 2020/21
1c – Blue Reef Aquarium to Southsea Esplanade
Eastney and Craneswater
Seawalls, revetments, other
Frontage provides protection to amenities and residential properties
10-15 years Reduce tidal flood risk from (existing) 5% AEP to 0.5% AEP by improving coastal defences. Proposed option(s): Construct a new wall landward of the promenade (1.2km). Hold The Line - maintain (450m)
PCC Phase 2 2025/26
Surface
Surface water management plan area
Overlap with other wards
Background informationProperties presently at risk (1% annual probability rain event)
Historic flood records
Proposed measuresProject lead
Completion date
Residential Commercial
13 – Pier Road (Little Morass)
n/a Flooding of Southsea Common, a topographical low point. Localised carriageway flooding occurs regularly
4 2 Good It is thought the local sewer network is part of the issue. PCC is monitoring
PCC / Southern Water
ongoing
14 – Southsea
Eastney and Craneswater
The area is flagged as having high surface water flood risk due to its low topography and combined drainage system. This is the first point of manhole surcharge if the Eastney pumping station were to fail
163 36 Very good
Southern Water surface water separation schemes across Portsmouth will significantly reduce the flows arriving at Eastney pumping station during a rain event. This will raise the standard of protection for the area. Both PCC and Southern Water have undertaken property level flood protection measures in the area
Southern Water
completed
Total 167 38
Groundwater
Groundwater desktop study targeted area
Overlap with other wards
Background information Proposed measures Project leadCompletion date
2 – Southsea Eastney and Craneswater
Highlighted as susceptible to groundwater emergence due to a geological permeability boundary
Gather information relating to groundwater levels, contaminants, sewer infiltration, sea defence integrity and ground infiltration rates, for sharing among partner organisations, internally to PCC and property developers. Will result in a groundwater trend report for the city of Portsmouth
PCC with support requested from Environment Agency, Southern Water, PCC planning department, Eastern Solent Coastal Partnership
2020
62 • Local flood risk management strategy • Eastney and Craneswater
Eastney and CraneswaterEastney and Craneswater ward is located on the southeastern corner of Portsea Island. There are large open spaces in the form of Canoe Lake, Highland Road Cemetery, the seafront, Fort Cumberland and some sports and recreational facilities.
The developed area is largely set back from the coast and is largely residential. The coastline runs from South Parade Pier to the western edge of Eastney Lake on The Solent and Langstone Harbour entrance. The Seafront Masterplan outlines proposals to improve the amenity value of the promenade.
Flooding
Eastney and Craneswater ward has some separate surface water and some combined sewer networks. The ward includes Eastney pumping station and associated rising mains, outfalls and holding tanks, which are critical to the drainage of Portsmouth.
There are sparse records of coastal flooding, although some wave overtopping has occurred in the past.
Tidal influence on the drainage network is particularly significant in this ward. Eastney and Craneswater ward forms part of two targeted
areas for groundwater investigation.
This area features in the Portsea Island Coastal Strategy Study – actions are outlined on the next page.
4i
3h
2g2f
2e
1d
1c
14
3
2
Key
PICSS flood cell 1
PICSS flood cell 2
Ward boundary
areas targeted for groundwater investigation
SWMP hotspots
Pier Road rock armour and frontage
Eastney and Craneswater • Local flood risk management strategy • 63
Coastal
AreaOverlap with other wards
Sea defence type(s)
Background information
Residential properties presently at risk (0.5% annual probability flood)
Proposed measures (target standard of protection 0.5%)
Responsible authority
FundingCompletion date
Blue Reef Aquarium to Southsea Esplanade (1c)
St Jude Seawall, revetments, other
Frontage provides protection to amenities and residential properties. Existing standard of protection varies between 0.5-100%
1872 New flood wall on landward side of promenade
PCC Flood Defence Grant in Aid
Beyond 2025
Southsea Esplanade (1d) n/a Seawalls
Melville Road caravan site to Fraser Battery (2e)
n/a Seawalls, revetments, groynes, embankments
Frontage provides protection to amenities and residential properties and some critical infrastructure. Existing standard of protection 100% at Fraser Battery
Raise and strengthen existing defences
Landowner/developer
Landowner/developer
Eastney Outfall to Langstone Channel (2f)
n/a Revetments, groynes, gabions
Frontage provides protection to residential properties and amenity. Existing standard of protection 0.5%
Replace structure fronting Eastney outfall at risk of failure with a new revetment and seawall
Landowner/developer
Landowner/developer
Langstone Channel to Eastney Lake (2g)
n/a Seawall, revetment, gabions
No works in short term n/a n/a n/a
Surface
Surface water management plan area
Overlap with other wards
Background informationProperties presently at risk (1% annual probability rain event)
Historic flood records
Proposed measuresProject lead
Completion date
Residential Commercial
14 – Southsea
St Jude High surface water flood risk due to its low topography and combined drainage system. First point of manhole surcharge if the Eastney pumping station were to fail
163 36 Very good
Southern Water surface water separation schemes will significantly reduce the flows arriving at Eastney pumping station during a rain event – raising the standard of protection for the area. PCC and Southern Water have undertaken property level flood protection measures
Southern Water
by 2015
Groundwater
Groundwater desktop study targeted area
Overlap with other wards
Background information Proposed measures Project leadCompletion date
2 – Southsea St Jude Highlighted as susceptible to groundwater emergence due to a geological permeability boundary
Gather information relating to groundwater levels, contaminants, sewer infiltration, sea defence integrity and ground infiltration rates, for sharing among partner organisations, internally to PCC and property developers. Will result in a groundwater trend report for the city of Portsmouth
PCC with support requested from Environment Agency, Southern Water, PCC planning department, Eastern Solent Coastal Partnership
20203 – Eastney Milton
64 • Local flood risk management strategy • Protecting individual residential properties
Protecting individual residential properties23 properties in Southsea have been fitted with special equipment, with the final property completed in February 2013. The properties were among the worst affected by floods that hit Southsea after a freak rainstorm in 2000.
The work was successfully undertaken after the council’s flood and drainage team successfully won a grant from the Environment Agency, the national body which deals with flooding.
Protection such as sealant for brickwork, special front doors, and flood resistant airbricks was put in place. It has been designed to cope with the kind of exceptional rainfall that has a 2% or more probability of occurring in any given year. This can be referred to as a 1 in 50 year standard of protection.
The work package included training for residents on how to manually deploy their flood defences in anticipation of a flood event, and ‘wet’ testing of the features once installed.
Flood doors across an internal garage, with removable central support post A freshly installed flood door being ‘wet’ tested
Flood insurance • Local flood risk management strategy • 65
The ABI and the government have recently agreed a Memorandum of Understanding (MoU) on how to develop a not-for-profit scheme – Flood Re – that would ensure flood insurance remains widely affordable and available. The MoU is a first step towards establishing Flood Re, and confirms it as the government’s preferred option.
Key elements of the framework are:
• Flood Re will be run and financed by insurers as a not-for-profit fund which will cover the cost of flood claims from high risk homes.
• Insurers will pass the flood risk element from those households deemed at high risk of flooding to the fund. Premiums for the flood risk will be calculated based on council tax banding up to a maximum limit depending on the band.
• Flood Re would charge member firms an annual charge of £180million. This equates to a levy of £10.50 on annual household premiums and represents the estimated level of cross-subsidy that already exists between lower and higher flood risk premiums.
• Flood Re will be designed to fully deal with at least 99.5% of years. Even in the worst half a percent of years, Flood Re will cover losses up to those expected in a 1 in 200 year – a year six times worse than 2007 – with government taking primary responsibility – working with the industry and Flood Re – for distributing any available resources to Flood Re policyholders should claims exceed that level.
Providing operational issues, including governance and regulatory approval, are resolved, the aim is for Flood Re to be up and running by summer 2015, with regular progress reviews taking place to ensure Flood Re can proceed. For now ABI members will voluntarily continue to meet their commitment to continue to offer flood cover to existing customers under the previous Flood Insurance Statement of Principles.8
A flood door being tested for leaks during the installation phase
Automatic airbricks installed
Flood insurance
66 • Local flood risk management strategy • Portsmouth City Council Coastal Partnership action plan
Portsmouth City Council Coastal Partnership action planLevel of assessment
Current status and/or proposed mitigation of flood risk Responsible authority
Funding source
Funding likelihood Expected completion
Portsea Island Coastal Strategy Study
1a – 1d Southsea (Harbour Railway to Royal Marines Museum)
Intermediate (Strategy)
Reduce tidal flood risk from (existing) 5% AEP to 0.5% AEP by improving coastal defences
Portsmouth City Council
Capital – FCRMGiA
Likely Phase 1: 2012/22
Phase 2: 2025/26
2e – 2g Eastney Spit (Royal Marines Museum to Eastney Lake)
Intermediate (Strategy)
Reduce tidal flood risk from (existing) 10% AEP to 0.5% AEP by improving coastal defences
Private Private Uncertain More likely beyond 2025
3h Eastney Lake Intermediate (Strategy)
Existing coastal defences provide tidal flood risk management up to 0.5% AEP. Continue to monitor and maintain condition of existing sea defences. Future capital improvements to coastal defences may be necessary to keep pace with sea level rise
Portsmouth City Council and private
Maintenance – PCC Revenue, Improvements – FCRMGiA and private
Unlikely, contributions required
2021/22
4i – 4l North Portsea Island (Twyford Avenue to Milton Common)
Intermediate (Strategy)
Reduce tidal flood risk from (existing) 10% AEP to 0.5% AEP by adapting to keep pace with sea level rise
Portsmouth City Council
Capital – EA FDGiA
Likely P)hased from 2015/16 to 2025/26
5m Tipner (Harbour Way to Twyford Avenue)
Intermediate (Strategy)
Statutory requirement to maintain the coastal defences to minimise the risk of any potential contaminates entering Portsmouth Harbour’s water body. Portsmouth Harbour is designated SAC, SPA, Ramsar and SSSi under the Habitats Regulations. Improvements to the coastal defences will be necessary, if the site is redeveloped, to manage the long term flood risk
Private Private Uncertain Flood improvements only achievable with regeneration
6n – 6p Continental Ferry Port
Intermediate (Strategy)
In order to maintain port operations the existing standard of flood risk management (1.3% AEP) is to continue. This can be achieved by adapting flood risk assets to keep pace with sea level rise
Portsmouth City Council
Capital – FCERMGiA
Unlikely, contributions required
Post 2021
7q HM Naval Base to Harbour Railway
Intermediate (Strategy)
Reduce tidal flood risk, to properties landward of HM Naval Base, from (existing) 2% AEP to 0.5% AEP by adapting to keep pace with sea level rise. The Ministry of Defence will continue to maintain it’s own National Defence operations at the HM Naval Base
Portsmouth City Council
Capital – FCERMGiA
Unlikely, contributions required
Post 2021
Portsmouth City Council Coastal Partnership action plan • Local flood risk management strategy • 67
Level of assessment
Current status and/or proposed mitigation of flood risk Responsible authority
Funding source
Funding likelihood Expected completion
Portchester to Emsworth Strategy
1a – 1b Portchester Castle to Paulsgrove
Intermediate (Strategy)
‘Hold The Line - Improve years 0-20 and Sustain 21-100’ PCC / FBC/private
FDGiA and contribution
FDGiA available to part fund scheme cost. Shortfall required to be fulfilled by contributions or cost savings. Development at Trafalgar Wharf being considered
2021/22
1c Horsea Island Intermediate (Strategy)
All epochs ‘Hold the Line - maintain years 0-100’ Private MoD Uncertain Uncertainty due to private ownership
M27 and Farlington Marshes
Intermediate (Strategy)
M27 All epochs ‘Hold The Line - Sustain years 0-100’ Private Highways Agency
Uncertain Uncertainty due to private ownership
Intermediate (Strategy)
Farlington Marshes ‘Hold the Line – Maintain years 0-20 with a Solent wide study to determine the long-term recommendations for the site. Hold the Line – Sustain or Managed Realignment years 21-100, based upon the Solent wide study recommendations’. In addition to a study looking across the context of the wider strategic network of sites, a study is required to confirm the future management of the site. This is likely to be a range of options from HTL to MR. This is likely to result in doing something different, to recognise coastal change. The study will address the economic, environmental and social implications and flood management issues of the site. To be reflected in the implementation plan of strategy and Action plan of the SMP. SMP, Strategy and Sustainability study are to have clear engagement plans. The SMP and Strategy will be advising the Regional Habitat Creation Plan of the likelihood of the need to provide compensatory habitat for the features and amenities of Farlington Marshes, and given the uncertain timescales this needs to be taken account of now
Portsmouth City Council
Revenue – maintenance. Possible capital – realignment
Uncertain Short term study completion years 2013 to 2018. Spend following outcomes of studies at latest after 2030
Portsmouth City Council Coastal Partnership action plan (continued)
68 • Local flood risk management strategy • Portsmouth City Council drainage team action plan
Portsmouth City Council drainage team action planLevel of assessment
Ward(s) Current status and/or proposed mitigation of flood risk Funding source
Funding likelihood
Expected completion
PCC drainage team
Surface water management plan
Cosham (north of railway line)
Intermediate Paulsgrove, Cosham, Drayton and Farlington
This is a large area flagged due to the topography used in the model. The EA first generation flood map AStSWF was used which doesn’t take into account drainage systems. It also treats the railway line as a bund, which is not the case as water can pass underneath the railway in several places through culverts. Recommended (in part) for groundwater investigation
PCC revenue
high 2020
Farlington Marshes
Intermediate Drayton and Farlington
There are no properties on the marshes to flood. The sea wall surrounding the marshes is nearing the end of its design life which the Coastal Partnership are addressing with the Environment Agency through a feasibility study. It has been discovered that a surface water sewer drains into the marshes via Station Road, Sainsburys and under the railway and A27. Investigations into the sewer function and integrity of the network, culverts and ditches are ongoing
PCC revenue / Southern Water reactive
high ongoing
War department sewer
Intermediate Hilsea, Copnor
A very small number of properties are effected by the low frequency flooding that occurs along its 2km length. Exact location and function of sewer is unclear but it is identified as a Southern Water asset. Further investigation required
Not yet known
not identified
ongoing
Anchorage Park
Intermediate Copnor There are no significant historic flooding events recorded here. The area is flagged as having high flood risk due to its low topography. The risk is further increased by the estate having a combined drainage system. Any surface water separation scheme would be very costly to implement. Recommended for groundwater investigation
PCC revenue
not identified
2020
Northern Parade (Alex Way area)
Intermediate Hilsea PCC are aware of the service road flooding and it has been documented numerous times. Residents’ garages are routinely flooded but internal properties are unaffected. Access to the sports facilities is affected but this is unadopted highway and is presently leased to Parkwood Leisure. The surface water catchment that feeds into the Alex Way sewer is relatively large for the pipes that currently serve it. A detailed model of the catchment has been produced by PCC, no easy solution has been found. Southern Water are aware of the issues and ongoing works to repair found blockages have not resolved the situation so far
PCC revenue / Southern Water reactive
high ongoing
Portsmouth City Council drainage team action plan • Local flood risk management strategy • 69
Level of assessment
Ward(s) Current status and/or proposed mitigation of flood risk Funding source
Funding likelihood
Expected completion
PCC drainage team
Surface water management plan
Copnor Road (Amberley Road area)
Detailed Hilsea, Copnor
Southern Water surface water scheme addressing the issues Copnor Road Scheme
Southern Water via OFWAT
Underway
completed
Quartremaine Industrial Estate
Intermediate Copnor Southern Water surface water scheme addressing the issues Quartremaine Road Scheme
completed
Great Salterns Golf Course
Intermediate Copnor, Baffins
Southern Water surface water scheme addressing the issues Great Salterns Scheme completed
Copnor Road (Monckton Road area)
Detailed Copnor Southern Water surface water scheme addressing the issues Kiln Road Scheme completed
Stamshaw Intermediate Nelson Southern Water pumping station upgrade addressing the issues Gruneisen Road Scheme completed
Ordnance Row
Intermediate Charles Dickens
The flooding at this location has been addressed by Southern Water through sewer cleaning and maintenance
Completed
Hambrook Street
Intermediate St Thomas We believe this was a one off incident caused by the flood of 2000. No further records of flooding in the area exist. Southern Water undertook sewer renovations in the area in 2007. Within area recommended for groundwater investigation
PCC revenue
high 2020
Pier Road (Little Morass)
Intermediate St Thomas, St Jude
Pier Road is a natural flood plain which floods during heavy rainfall, no properties are affected. Access to sea front is affected but there are numerous alternative routes. Within area recommended for groundwater investigation
PCC revenue
high 2020
Southsea (Great Morass)
Detailed St Jude, Eastney and Craneswater
The Southern Water surface water separation schemes will help reduce the flows to the existing systems. The recent Blue Flag sewer renovation works carried Southern Water has improved the capacity of the current system which has further reduced the flood risks. Within area recommended for groundwater investigation
PCC revenue
high 2020
SuDS Approval Body Detailed ALL citywide
A sub-element of planning applications which requires separate drainage submission for new developments. High potential to reduce flood risk
Fee charged to developers
high unknown
Groundwater Information gathering
Desktop study
ALL citywide
Groundwater monitoring information in partnership with other agencies at strategic locations
Revenue high 2020
PCC / Colas
Highway drainage local level ALL citywide
Reactive and proactive maintenance of highways drainage PFI funded high 2029
Portsmouth City Council drainage team action plan (continued)
70 • Local flood risk management strategy • Southern Water Services action plan
Southern Water Services action planScheme / procedure Level of
assessmentPrimary type of flood risk
Ward(s) Current status and/or proposed mitigation of flood risk Funding source
Funding likelihood
Expected completion
AMP5 Business Plan 2010-2015
Kirtley Close CSO Detailed
Surface water
Drayton and Farlington
New flap valves, access route and renovation to prevent tide locking influence
completed
Spice Island Detailed St Thomas Lining of sewers to reduce seawater infiltration and some remedial gully rerouting
completed
Gruneisen Road Detailed Nelson Pumping station upgrade and capacity increase OFWAT
Awarded completed
Great Salterns Detailed Copnor, Baffins
New channel and culvert to handle additional flows from schemes to the north of the area. Pumping station upgrade
OFWAT
Tangier Road Detailed Baffins Surface water separation OFWAT
Copnor Road Detailed Hilsea, Copnor
Surface water separation. New pumping station OFWAT
Quartremaine Road Detailed Copnor Surface water separation. Upgrade Great Salterns pumping station OFWAT
Kiln Road Detailed Copnor Surface water separation. New pumping station OFWAT
HM Naval Base Detailed Charles Dickens
Surface water separation OFWAT
Rodney Road Detailed Milton Surface water separation, may be shelved depending on flow savings at Eastney being achieved by the above
OFWAT
AMP6 Business Plan 2015-2020
Information not yet available
High level
Foul water
n/a Information not yet available OFWAT high covers period 2015-2020
AMP7 Business Plan 2020-2025
Information not yet available
High level n/a Information not yet available OFWAT high covers period 2020-2025
Drainage Area PlanHigh level ALL
citywideInformation not yet available – To inform AMP applications SW
Revenuehigh covers period
2015-2020
Long Term Sewerage PlanHigh level ALL
citywideInformation not yet available – To inform AMP applications SW
Revenuehigh covers period
2015-2020
Drainage Maintenancen/a ALL
citywideOngoing – reactive and proactive fixes to main sewers Revenue high ongoing
Environment Agency action plan • Local flood risk management strategy • 71
Scheme / procedure Level of assessment
Primary type of flood risk Ward(s) Current status and/or proposed mitigation of flood risk Funding source
Funding likelihood
Expected completion
Flood Warning ServiceDetailed Fluvial and coastal ALL citywide EA to continue with flood warning activities and improvements
to improve resilience to floodingEA high ongoing
Sea wall maintenanceDetailed Coastal Baffins,
Drayton and Farlington
EA to continue current maintenance activities, pending future management decisions in some locations (e.g. Farlington Marshes)
EA high ongoing
Farlington Marshes culvert worksDetailed Coastal Drayton and
FarlingtonInstallation of flood control structures to vehicle/cattle underpass and culvert beneath A27 at Farlington Marshes to reduce risk of tidal inundation
EA high completed
Main river management
Detailed Fluvial Copnor, Baffins, Drayton and Farlington
Permissive powers to undertake work as necessary; issue of permits under Water Resources Act 1991 and Southern Region Byelaws
EA high ongoing
Production and updating of national flood maps
High level Surface water, main river, reservoir and coastal
ALL citywide Hazard mapping for rivers and sea, and UFMfSW (Updated Flood Map for Surface Water), both available at the end of 2013
EA high ongoing
Production of national flood plans, strategies and guidance
High level Surface water, main river, reservoir and coastal
ALL citywide Responsible for the delivery of national plans and strategies like River Basin Management Plans, Catchment Flood Management Plans, Portchester to Emsworth Flood and Coastal Erosion Risk Management Strategy
EA high ongoing
Advice on flood risk to new development
Detailed Surface water (pending SAB), main river, coastal, reservoir, groundwater
ALL citywide EA to continue to provide advice on strategic planning documents and site specific development proposals in relation to flood risk
EA high ongoing
Respond to pollution incidents Detailed All ALL citywide Reactive and proactive (e.g. bathing water quality sampling) EA high ongoing
Environment Agency action plan
72 • Local flood risk management strategy • What you can do to minimise the effects of flooding
What you can do to minimise the effects of floodingEnvironment Agency advice on preparing for a flood9
Sign up to Flood Warnings Direct (see also page 60)
To register by telephone, or if you need help during the registration process, please call Floodline on 0845 988 1188.
Make a personal flood plan
Plan in advance what you will do if your property floods. You can complete a personal flood plan online by visiting www.environment-agency.gov.uk and search floods.
Complete a community flood plan
This is so community members and groups know how they will work together to respond quickly when flooding happens. This advice is for people active in the local community, leaders of community groups, schools, hospitals or residential care homes and anyone else involved in supporting communities to be better prepared for flooding.
Prepare a flood kit
Put together a kit of essential items you’ll need to hand if it floods.
Would you need extra support during a flood?
As part of your flood planning we recommend you think about who you can ask for assistance before, during and after a flood. The EA can also deliver flood warnings for your property to a relative or friend, so that they are aware when you may need help. You can set this up by phoning Floodline on 0845 988 1188.
Prepare your property for flooding
It’s impossible to completely flood-proof a property but there are lots of things you can do to reduce flood damage. Some useful information and advice on buying flood protection products is available at www.environment-agency.gov.uk and search floods.
© Crown, Met Office and Environment Agency 2012 Page 1 of 3http://www.ffc-environment-agency.metoffice.gov.uk
Flood Guidance Statement 10:30hrs 19 December 2012Our assessment of daily flood risk for England and Wales is below.
10:30 - 23:59hrsWednesday
19 December 2012
00:00 - 23:59hrsThursday
20 December 2012
00:00 - 23:59hrsFriday
21 December 2012
00:00 - 23:59hrsSaturday
22 December 2012
00:00 - 23:59hrsSunday
23 December 2012
Headline
Significant river and surface water flooding likely from Wednesday evening through Thursday. This is a period ofraised flood risk generally, with further significant disruption possible over the weekend.
General Overview of Flood Risk
Successive periods of rain moving across England and Wales are falling on wet ground leading to the potential for significantdisruption across much of southern and central England and southeast Wales on Wednesday into Thursday. For southerncoastal counties and in Northamptonshire the flood risk is MEDIUM, as coloured amber on the maps above, while the floodrisk is LOW where the counties are coloured yellow.
Residual flood risks are then maintained for Friday as river response is likely to be ongoing, particularly in Northamptonshireand along the Rivers Severn, Thames and Trent.
Further rainfall is then expected on Saturday. This is most likely to affect southwest England and parts of Wales and followingon from wet conditions on Wednesday and Thursday there remains the potential for some significant impacts here and so theflood risk is currently LOW.
Ongoing flooding issues on the Somerset Levels and in Dorset and Wiltshire may be exacerbated by further rainfall.
The FGS will be updated this afternoon.
Warnings and Alerts in force in England and Wales at 10:30hrs
Flood (click here)0 Severe Flood Warnings / 4 Flood Warnings / 37 Flood Alerts
Severe Weather (click here)Alerts - Yes / Warnings - Yes
Best Judgement
An example of a Flood Guidance Statement issued by the Met Office
References • Local flood risk management strategy • 73
If you would like to report a flood:There are a number of processes in place by which you can report a flood, or issues with the drainage system like blocked gullies:
• To report an issue with gullies anywhere in the city complete the form by visiting www.portsmouth.gov.uk and search for ‘report it gullies’. You will need to supply an accurate address to allow us to find the gully and short description of the problem.
• Direct to the council’s Drainage Team at [email protected] or phone 023 9284 1588 which will be picked up by a PCC Drainage Officer.
• If you believe a flood contains wastewater, PCC advises that you contact Southern Water directly, by filling out an enquiry form at www.southernwater.co.uk and search for ‘wastewater enquiries’ or phone 0845 278 0845. PCC does not have the power to work on sewers or structures owned by third parties or other Risk Management Authorities, but we do work together to resolve issues.
• PCC City Help Desk 023 9283 4092.
• Colas 023 9231 0900. Many local issues, where appropriate, are passed to Colas by PCC to investigate under the terms of the Private Finance Initiative (PFI) agreement, which is in place until 2029. In normal circumstances reported issues are investigated and actioned within 28 days but in reality it is highly likely to be much quicker. You may wish to call them directly.
• For social housing, we recommend you contact your area housing office in the first instance. Visit www.portsmouth.gov.uk and search for area housing office.
• IN AN EMERGENCY, CALL 999 IF YOU ARE IN DANGER OR PEOPLE HAVE BEEN INJURED.
References1. www.solentpedia.info/our_changing_coast/coastal_squeeze
2. www.environment-agency.gov.uk/homeandleisure/37837.aspx
3. www.environment-agency.gov.uk/homeandleisure/floods/31680.aspx
4. en.wikipedia.org/wiki/Thames_barrier
5. www.gov.uk/government/news/ new-streamlined-planning-guide-launched-online
6. www.push.gov.uk
7. Environment Agency
8. www.abi.org.uk/News/News-releases/2013/06/ABI-and-Government-agree-Memorandum-of-Understanding-on-scheme-to-safeguard-UK-flood-insurance
9. Environment Agency
10. Environment Agency
Southsea Castle sea defences. © ‘The News’, Portsmouth
74 • Local flood risk management strategy • Glossary of terms
Glossary of termsTerm MeaningThe ‘Act’ The Flood and Water Management Act 2010.
AEP Annual Event Probability – see SoP / Standard of Protection.
Aquifer A source of groundwater comprising water bearing rock, sand or gravel capable of yielding significant quantities of water.
AMP5/6 Asset Management Plan – A plan for managing water and sewerage company (WaSC) infrastructure and other assets in order to deliver an agreed standard of service. AMP5 covers the period 2010-2015, AMP6 2015-2020.
BREEAM BRE Environmental Assessment Method is the world’s foremost environmental assessment method and rating system for buildings.
CFMP Catchment Flood Management Plan: A high-level planning strategy through which the Environment Agency works with their key decision makers within a river catchment to identify and agree policies to secure the long-term sustainable management of flood risk.
Climate Change Long term variations in global temperature and weather patterns caused by natural and human actions.
Combined sewer A sewer that drains both rainwater and foul water.
CSO Combined sewer overflow. When a combined sewer reaches capacity it can overflow into another sewer (often a surface water sewer) at strategic points to relieve pressure and reduce the risk of foul water flooding.
Culvert A channel or pipe that carries water below the level of the ground.
Defra Department for Environment, Food and Rural Affairs.
EA Environment Agency.
ESCP Eastern Solent Coastal Partnership.
FDGiA Flood Defence Grant in Aid – Environment Agency controlled national funding stream for flood defence works.
Flood defence Infrastructure used to protect an area against floods, such as floodwalls and embankments; they are designed to a specific standard of protection (design standard).
Flood Risk Area An area determined as having a significant risk of flooding in accordance with guidance published by Defra and WAG.
FRR Flood Risk Regulations 2009; Transposition of the EU Floods Directive into UK law. The EU Floods Directive is a piece of European Community (EC) legislation to specifically address flood risk by prescribing a common framework for its measurement and management.
HIOW Hampshire and Isle of Wight.
HRA Habitat Regulations Assessment.
Impermeable A surface, geology type or structure through which water can NOT travel.
LDF Local Development Framework.
LLFA Lead Local Flood Authority – Local Authority responsible for taking the lead on local flood risk management.
Glossary of terms • Local flood risk management strategy • 75
Term MeaningLRF Local Resilience Forum – a multi-agency forum of all the organisations that have a duty to cooperate under the Civil Contingencies
Act 2004, and those involved in responding to emergencies. They prepare emergency plans in a co-ordinated manner.
LPA Local Planning Authority.
MoD Ministry of Defence.
OFWAT The economic regulator of the water and sewerage sectors in England and Wales.
PCC Portsmouth City Council.
PEMS Portchester Castle to Emsworth Coastal Strategy.
Permeable A surface, geology type or structure through which water can travel.
PFRA Preliminary Flood Risk Assessment.
PPS25 Planning Policy Statement 25: Development and Flood Risk.
PICSS Portsea Island Coastal Defence Strategy Study.
RBMP River Basin Management Plan – South East.
RFCC Regional Flood and Coastal Committee – Portsmouth is within the Southern RFCC region.
Risk In flood risk management, risk is defined as a product of the probability or likelihood of a flood occurring, and the consequence of the flood.
RMA Risk Management Authority – specifically for Portsmouth these are the EA, LLFA, water company and the highway authority.
SAB SuDS Approval Body.
SEA Strategic Environmental Assessment.
SE7 South East Seven.
SFRA Strategic Flood Risk Assessment.
SMP Shoreline Management Plan.
SoP / Standard of Protection10
The standard to which an area is protected against flooding. This is generally expressed as a Annual Event Probability (AEP). For example, an SoP of 10% means an area is protected against a flood with a 10% probability of occurring in any given year. An SoP of 0.5% AEP means an area is protected against a flood with a 0.5% probability of occurring in any given year. The flood with a 0.5% AEP has a lower likelihood of occurring than a flood with a 10% probability, but will be greater in severity (higher water levels). A 0.5% AEP standard of protection is therefore higher than a 10% standard of protection.
The ‘Strategy’ PCC Local Flood Risk Management Strategy.
SuDS Sustainable Drainage System – Methods of management practices and control structures that are designed to drain surface water in a more sustainable manner than some conventional techniques. For example, releasing rainwater directly back to the environment instead of traditional piped networks.
SWMP Surface Water Management Plan.
WFD EU Water Framework Directive.
Designed by: [email protected] Published: March 2015 Ref: 13.2
You can get this Portsmouth City Council information in large print, Braille, audio or in another language by calling 9284 1588.
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Coastal and Drainage Team Transport and Environment Portsmouth City Council Civic Offices Guildhall Square Portsmouth PO1 2NE
Telephone: 023 9284 1588 Email: [email protected]
