Climate Change Effects on the Hydrology and Water Resources Availability in the Nadi basin

Report by Andre Siohane & Rinesh Ram

Physical characteristics

Watershed area = 516 km2

Watershed perimeter = 156.28 km

Major Rivers & Creeks

Nadi River Namosi River Nawaka River Masi Creek Malakua Creek Lawatoya Creek

Typical Weather Mostly humid and dry Average rainfall around 2000 mm in western division

Winter weather with clear or partly cloudy skies, much sunshine

A well-developed west to northwesterly sea breeze by day

South easterlies are predominant at night and in all months except from August to March when wind is generally from the northwesterly quarter

And relatively cool nights

Nadi watershed is affected by global land regional-scale climatic events such as El Nino and La Nina resulting from inter-annual variations of the strength of the ‘‘Walker Circulation’’ over the equatorial Pacific Ocean and associated droughts and/or floods, tropical cyclones, and high waves

Climate Change

Change in normal climate that we know or a change in the weather pattern that we have been experiencing for the past years/decades

Change in weather means a change in the processes within the hydrological cycle, which develops the weather, and eventually leading to changes in the physical and chemical characteristics of surface and subsurface water resources

Evaporation and precipitation are the two most important processes in the hydrological cycle that govern the weather in any given location where their rates depend on land & sea surface temperatures, which decides the intensity of rainfall and temperature.

Rainfall Trends at Nadi Airport: Annual rainfall

El nino period from 04/97 to 06/98

Notes:- The graph shows no significant change in annual rainfall- Note variation between yearly rainfall

Rainfall Trends at Nadi Airport: Wet Season

Rainfall Trends at Nadi Airport: Dry Season

Temperature Trends at Nadi Airport: Annual M aximum

Temperature Trends at Nadi Airport: Annual M inimum

Link between El nino and Climate change

There may be no confirmed links yet, but over time the strength of this event, in terms of heating the environment, has increased

Complications of Climate Change to Water M anagers today

Complications of Climate Change to Water M anagers today

Hazards : floods, droughts, cyclones, landslides in waterways, low/high flows, sea level rise

Water quality: pollution, algal blooms (heat/chemicals/animal & human waste), turbidity, salinity

High water demand, increasing population, water loss limited water supply

Infrastructure, maintenance, and monitoring

IWRM Planning in the context of Climate Change

Step 1: Plan the overall process with all stakeholders

Step 2: Analyze the situation

Step 3: Develop the responseDevelop individual options

Step 4: Implement the response

Step 5: Monitor, Evaluate, and review

Recommendations

Improve water storage infrastructure: Good effect of climate change is the opportunity given to store water due to increased rainfall during wet season for farmers and communities

Capacity building in all water sectors and communities and awareness on sustainable use of water

Local and commercial water use planNBCC to have consultation with members of catchment

committees that already exist in the pacific region, to learn from the challenges they faced and resolutions they applied

Recommendations (continued)

It is important that greater emphasis be placed on meteorological and environmental monitoring, vulnerability assessments be undertaken and adaptation options e.g restricting development in threatened coastal and

floodplain areas, put in place. Improve and promote continuous monitoring of

rainfall/temperature, discharge, coastal water quality, and reef/coral health for the benefit of marine ecosystems and tourism

Recommendations (continued)

Monitor the water resource characteristics of the Nadi Basin, by data collection on hydrology, climate, behaviour of the rivers to the context of climate change and also for disaster responses. Database useful data for better understanding of the water resource

Develop and implement effective water demand management programs through: investigating the system loss (leakage Control) and pressure reduction program (reduce pressure during off

peak hours to increase the life of pipes introduce Water Use Efficiency program in the tourism

industry (eg. low flow showerheads, reuse wastewater, low flow toilets etc..

Recommendations (continued)

Encourage construct water reservoirs upstream for economic development, flood mitigation, and water availability during low rainfall period this will improve water resource management and supply to communities

Public and community awareness programs on the climate change impacts on the basin water resource, natural disasters and water use

Government support for the IWRM Nadi Basin catchment Committee for sustainability after the 5 year project period

Develop policies and regulation to protect the watershed, monitor the uses and the development that occurs at the basin, such as buffer zones, re-planting forest etc...

Conclusion

Climate Change Effects on the Hydrology and Water Resources Availability in the Nadi basin

Climate change adverse effects in the Nadi basin come as events of heavy rainfall/rainfall intensity, flooding, and coastal inundation of low lying areas

At present the watershed is being more affected by human activity, in various land uses which have the capacity to increase the effects of climate change ten fold

There is need for the awareness/capacity building of decision makers and communities concerning the effects of climate change to better prepare Nadi for impacts of climate change in the future