Environmental flows: The concept and applications in India
-
Upload
international-water-management-institute-iwmi -
Category
Environment
-
view
163 -
download
0
description
Transcript of Environmental flows: The concept and applications in India
ENVIRONMENTAL FLOWS: THE CONCEPT AND APPLICATIONS IN INDIA
VLADIMIR SMAKHTINInternational Water Management Institute, Colombo, Sri Lanka
Ministry of Water Resources, New Delhi, India,4 November, 2014
ENVIRONMENTAL FLOWS (EF) – WHAT IS THIS?
• A compromise between water resources development and maintenance of a river in an agreed / prescribed condition
• Expressed as a set of flow releases / continuous hydrograph, which mimics the elements of natural flow regime
• Different flows perform different environmental and social functions - elements of high, medium and low flows have to be included into EF
• The more natural / healthy we want a river to be – – the more water, in total, we need to leave in it,– the more natural flow variability we need to maintain
ENVIRONMENTAL FLOWS – WHERE ARE THEY?
Potentially utilizable water (for agriculture, industry etc)
Total resource capacity, e.g. “natural” Mean Annual Runoff (MAR)
Total volume of ENVIRONMENTAL FLOWS (varies depending on Desired Environmental Condition e.g. pristine, good, fair )
ENVIRONMENTAL FLOW METHODOLOGIES
• Hydrological (based on hydrological data and ecological perceptions)– % of MAR (e.g.10% MAR - poor condition, 60% MAR - optimal)– low-flow indices from Flow Duration Curve (Q95, Q75...)– time series analyses (e.g. Range of Variability Approach –RVA)
• Hydraulic rating or habitat simulation– simple relationships between a hydraulic variable (surrogate for
habitat factors, e.g. wetted perimeter) and discharge– modelling of relationships between quantity and suitability of habitat
for target species under different discharges
• Holistic – take into account multiple environmental and social factors– require multidisciplinary panels of experts– Building Block Methodology (BBM)
TWO-LEVELS’ EF ASSESSMENT FRAMEWORKIdeal for any country
• DESKTOP :– Planning / Reconnaissance level– Limited developments in a river basin – Quick and parsimonious
• DETAILED :– Intermediate or comprehensive level (differ in data input)– High priority rivers, allocation tradeoffs– Data intensive, field data collection
IWMI EF WORK
• Global, and in less exposed countries in Africa and Asia: India, Nepal, Sri Lanka, Ethiopia, Viet Nam, Azerbaijan
• Primary focus - planning type assessment, based on Flow Duration Curves. More complex approaches in Viet Nam and India
• Inclusion of EF in water allocation modeling
• TO MAINTAIN A FAIR ECOLOGICAL CONDITION OF RIVERS WORLDWIDE, EF IN THE RANGE OF 20-50% OF MAR ARE NEEDED (ON AVERAGE, ABOUT 30%)
GLOBAL EF OUTLOOKestimated % of the annual river flow needed for ecological purposes
AMAZON
0
5
10
15
20
25
30
1 2 3 4 5 6 7 8 9 10 11 12
Months of the year
% o
f the
tota
l ann
ual f
low
LIMPOPO
0
5
10
15
20
25
30
35
40
1 2 3 4 5 6 7 8 9 10 11 12
Months of the year
% o
f th
e t
ota
l an
nua
l flo
w
ENVIRONMENTAL WATER SCARCITYEnvironmentally “safe”
river basinEnvironmentally “water scarce”
river basin
Total water available
Utilizablewater
Environmental needs
Actual use
Total wateravailable
Environmental needs
Utilizablewater
Actual use tappinginto environmentalwater needs
GLOBAL ENVIRONMENTAL WATER STRESS INDEX Total withdrawals as a proportion of water available once EF are satisfied
Total water available
Utilizablewater
Environmentalneeds
Actual use
Total water
available
Environmentalneeds
Utilizablewater
Actual use tappinginto environmentalwater needs
DESKTOP/ PLANNING EF APPROACH FOR INDIA
• Combine flow variability with ecological management categories (EMC) to determine EF for different river conditions
• Flow variability is represented by modified Flow Duration Curves – a cumulative distribution of discharges
• A procedure is developed for assessment of the most suitable EMC using expert assessment and scoring of ecological indicators: – Rare and endangered aquatic biota (primarily fish)– Overall richness of aquatic species (fish)– Presence of protected areas– Degree of flow regulation– % of the basin remaining under natural cover types, – other
ENVIRONMENTAL MANAGEMENT CLASSES
EMC ECOLOGICAL DESCRIPTION MANAGEMENT PERSPECTIVE
A: Natural Pristine condition or minor modification of in-stream and riparian habitat
Protected rivers and basins. Reserves and national parks. No new water projects allowed.
B: Slightly modified
Largely intact biodiversity and habitats despite water resources development and/or basin modifications.
Water supply schemes or irrigation development present or allowed.
C: Moderately modified
The habitats and dynamics of the biota have been disturbed, but basic ecosystem functions are intact.
Multiple disturbances associated with the need for socio-economic development, e.g. dams, diversions, etc
D: Largely modified
Large changes in natural habitat, biota and basic ecosystem functions have occurred. A clearly lower than expected species richness.
Significant and clearly visible disturbances associated with basin and water resources development, including dams, diversions, transfers, habitat modification and water quality degradation
E: Seriously modified
Habitat diversity and availability have declined. A strikingly lower than expected species richness. Alien species have invaded the ecosystem.
High human population density and extensive water resources exploitation.
F: Critically modified
Modifications have reached a critical level and ecosystem has been completely modified with almost total loss of natural habitat and biota.
This status is not acceptable from the management perspective. Management interventions are necessary to restore flow pattern, river habitats etc (if still possible / feasible).
LATERAL SHIFT OF A FLOW DURATION CURVE
• A natural (reference) FDC is calculated from monthly flow time series• A shift of 1 step is equivalent to “moving” a river from a higher EMC to the
next (lower) one (e.g. from class ‘A’ to class ‘B’)
100.0
1000.0
10000.0
0.01 0.1 1 5 10 20 30 40 50 60 70 80 90 95 99 99.9 99.99
% Time flow exceeded
Month
ly F
low
(M
CM
)
Original A class B class C class D class
Direction of shift
Reference (original) FDC
AB
C
D
EXAMPLES OF ESTIMATED EF DURATION CURVES
0.1
1.0
10.0
100.0
1000.0
10000.0
100000.0
0.01 0.1 1 5 10 20 30 40 50 60 70 80 90 95 99 99.9 99.99
% Time flow exceeded
Mon
thly
Flo
w (
MC
M)
Original A class B class C class D class Class E Class F
KRISHNA OUTLET
1.0
10.0
100.0
1000.0
10000.0
100000.0
0.01 0.1 1 5 10 20 30 40 50 60 70 80 90 95 99 99.9 99.99
% Time f low exceeded
Mon
thly
Flo
w (
MC
M)
Original Class A Class B Class C Class D Class E Class F
MAHI OUTLET
ESTIMATES OF LONG-TERM EF VOLUMES AT 13 MAJOR RIVER BASIN OUTLETS FOR DIFFERENT EMC
River Natural MAR, BCM*
EF (% natural MAR)
Class A Class B Class C Class D Class E Class F
Brahmaputra 585 78.2 60.2 45.7 34.7 26.5 20.7
Cauvery 21.4 61.5 35.7 19.6 10.6 5.8 3.2
Ganga 525 67.6 44.2 28.9 20.0 14.9 12.1
Godavary 110 58.8 32.2 16.1 7.4 3.6 2.0
Krishna 77.6 62.5 35.7 18.3 8.4 3.5 1.5
Mahanadi 66.9 61.3 34.8 18.5 9.7 5.6 3.6
Mahi 11.0 41.9 17.1 6.5 2.3 0.8 0.3
Narmada 45.6 55.5 28.8 14.0 7.1 3.9 2.5
Pennar 6.3 52.7 27.9 14.3 7.3 3.8 2.0
Tapi 14.9 53.2 29.9 16.6 9.0 4.9 2.6
Periyar 5.1 62.9 37.3 21.2 12.1 6.9 3.9
Sabarmati 3.8 49.6 24.2 12.1 6.6 3.7 2.1
Subarnarekha 12.4 55.0 29.9 15.4 7.4 3.4 1.5
SIMULATING A TIME SERIES OF EF AT A SITE
Once an EF FDC is established, a simple spatial interpolation procedure is used to simulate the final output of the EF assessment- monthly EF time series
EXTRACTS FROM ACTUAL AND SIMULATED TIME SERIES AT VIJAYAVADA (KRISHNA OUTLET)
0
5000
10000
15000
20000
25000
30000
35000
1 11 21 31 41 51 61
Months since January 1991
Mo
nth
ly fl
ow
s (M
CM
)
Observed at present Simulated natural EFR Class B EFR Class D
Simulated Natural
ObservedEFR scenario 1
EFR scenario 2
DESKTOP EF CALCULATORSGlobal, Ganges basin, Sri Lanka
OUTPUTS AND TOOLS AVAILABLE FOR USE / FURTHER REFINEMENT
• An EF quick assessment methodology which could be replicated in other basins and in the same basins – with addition data, at different reaches
• Estimates of EF for each major basin outlet in the form of:– EF Duration Curves for each EMC,– Corresponding EF estimates as % of natural MAR– Corresponding EF monthly time series
• Software tools (Ganges and Global EF Desktop calculators)
• Publications (IWMI Research Reports, Water Policy Briefs, etc)
DETAILED, PARTICIPATORY METHODSUPPER GANGES, UPSTREAM OF KANPUR
• Collaboration between WWF-India – IWMI - IHE and other partners • First time in India• Iconic river – lots of cultural and religious angles never explored before• Multidisciplinary (some 10 different specialists)• Modified Building Block Method (BBM)
BUILDING BLOCKS METHOD• BBM stages:
– Reconnaissance, geomorphological survey, and EF sites selection– Biological and social surveys – Hydrological analysis– Hydraulic sections surveys– Specialist workshop where EF are determined
• “Building Blocks” include Low and High flows for all 12 months
• Driest month and wettest month are analyzed first, interpolation is possible in-between
• Flow needs of various components (fish, spiritual needs) are normally expressed as water level, velocity, width etc.
• They are converted to discharges using hydraulics and evaluated by hydrology. The largest requirement is accepted as BB.
21
Zone 1 Gangotri to Rishikesh
Zone 3 Narora to
Farrukhabad
Zone 4 Kannauj to
Kanpur
EF SUMMARY, ZONE 1: GANGOTRI- RISHIKESH maintenance flows
0
2000
4000
6000
8000
10000
12000
14000
1 2 3 4 5 6 7 8 9 10 11 12
Months
Flo
w V
olum
e, M
CM
maintenance low maintenance high natural total
Site EF1 -Kaudiala EMC A; 72% MAR
EF SUMMARY, ZONE 3: NARORA – FARRUKHABAD maintenance flows
0
2000
4000
6000
8000
10000
12000
14000
1 2 3 4 5 6 7 8 9 10 11 12
Months
Flo
w V
olum
e, M
CM
maintenance low maintenance high natural total Present
Site EF3 –Kachla Ghat EMC B, 45% MAR
PLANNING (GANGES CALCULATOR) AND COMPREHENSIVE (BBM) RESULTS COMPARED
EF Site N
EF Site Name
EMC BBM Workshop result(Total EF as % of natural MAR)
Ganges Calculator Result (Total EF as % of natural MAR)
1 Kaudiala A 72 67
2 Kachla Ghat B 45 36
3 Bithoor B 47 35
SUMMARY
• EF- is a tool to maintain a river in an agreed condition. EF need to mimic natural flow variability
• A combination of simple (planning) and comprehensive (holistic) EF assessment tools is ideal for EF management. The levels of accuracy and confidence differ, but both types of tools have distinct purposes.
• A number of EF tools and information, freely available, are already developed for India - for further use and refinement with Indian partners and responsible agencies
• Previous studies were normally carried out in the conditions of lack of access to hydrological and hydraulic data. To enhance national EF work, access to these data is imperative.
• Actual EF provisions are not the same as estimated EF. No matter how advanced and accurate the estimates are, its output remains on paper if no actual implementation is made. It needs Policy and Institutional support.
THANK YOU !THANK YOU !