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

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LIMPOPO

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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

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% Time flow exceeded

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ly F

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Direction of shift

Reference (original) FDC

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EXAMPLES OF ESTIMATED EF DURATION CURVES

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Original A class B class C class D class Class E Class F

KRISHNA OUTLET

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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)

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Months since January 1991

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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

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maintenance low maintenance high natural total

Site EF1 -Kaudiala EMC A; 72% MAR

EF SUMMARY, ZONE 3: NARORA – FARRUKHABAD maintenance flows

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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 !