Presented by Vladimir Smakhtin at the Ministry of Water Resources, New Delhi, India, November 4, 2014. The flows of India’s rivers are increasingly being modified by dams and weirs and abstractions for agriculture and urban use. These interventions have caused significant alteration of flow regimes mainly by reducing total flow and affecting its variability and seasonality. An Environmental Flow (EF) is the water regime provided within a river, wetland or coastal zone to maintain ecosystems and their benefits. Environmental Flows describe the quantity, quality and timing of water flows required to sustain freshwater and estuarine ecosystems and the human livelihoods and well-being that depend on these ecosystems. This presentation looks at how the EF approach has been tested in India and describes a project to apply EF methodology to the upper Ganga.

1. ENVIRONMENTAL FLOWS:
THE CONCEPT AND APPLICATIONS IN INDIA
VLADIMIR SMAKHTIN
International Water Management Institute, Colombo, Sri Lanka
Ministry of Water Resources, New Delhi, India,
4 November, 2014

2. 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

3. 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 )

4. 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)

5. TWO-LEVELS’ EF ASSESSMENT FRAMEWORK
Ideal 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

6. 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

7. GLOBAL EF OUTLOOK
estimated % of the annual river flow needed for ecological purposes
AMAZON
40
35
30
25
20
15
10
5
30
25
20
15
10
5
• TO MAINTAIN A FAIR ECOLOGICAL CONDITION OF RIVERS WORLDWIDE, EF IN
THE RANGE OF 20-50% OF MAR ARE NEEDED (ON AVERAGE, ABOUT 30%)
0
1 2 3 4 5 6 7 8 9 10 11 12
Months of the year
% of the total annual flow
LIMPOPO
0
1 2 3 4 5 6 7 8 9 10 11 12
Months of the year
% of the total annual flow

8. ENVIRONMENTAL WATER SCARCITY
Environmentally “safe”
river basin
Environmentally “water scarce”
river basin
Total water
available
Utilizable
water
Actual use
Environmental
needs
Total water
available
Environmental
needs
Utilizable
water
Actual use tapping
into environmental
water needs

9. GLOBAL ENVIRONMENTAL WATER STRESS INDEX
Total withdrawals as a proportion of water available once EF are satisfied
Total water
available
Utilizable
water
Actual use
Environmental
needs

10. 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

11. 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).

12. 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’)
10000.0
1000.0
100.0
Direction of
shift
Reference (original)
FDC
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
Monthly Flow (MCM)
Original A class B class C class D class
A
B
C
D

13. EXAMPLES OF ESTIMATED EF DURATION CURVES
100000.0
10000.0
1000.0
100.0
10.0
100000.0
10000.0
1000.0
100.0
10.0
1.0
0.1
MAHI OUTLET
KRISHNA OUTLET
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
Monthly Flow (MCM)
Original A class B class C class D class Class E Class F
1.0
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
Monthly Flow (MCM)
Original Class A Class B Class C Class D Class E Class F

14. 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

15. 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

16. EXTRACTS FROM ACTUAL AND SIMULATED TIME
SERIES AT VIJAYAVADA (KRISHNA OUTLET)
35000
30000
25000
20000
15000
10000
5000
0
1 11 21 31 41 51 61
Months since January 1991
Monthly flows (MCM)
Observed at present Simulated natural EFR Class B EFR Class D
Simulated Natural
Observed
EFR scenario 1
EFR scenario 2

17. DESKTOP EF CALCULATORS
Global, Ganges basin, Sri Lanka

18. 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)

19. DETAILED, PARTICIPATORY METHODS
Upper 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)

20. 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
21
Zone 4
Kannauj to
Kanpur

22. EF SUMMARY, ZONE 1: GANGOTRI- RISHIKESH
maintenance flows
14000
12000
10000
8000
6000
4000
2000
0
Site EF1 -Kaudiala EMC A; 72% MAR
1 2 3 4 5 6 7 8 9 10 11 12
Months
Flow Volume, MCM
maintenance low maintenance high natural total

23. EF SUMMARY, ZONE 3: NARORA – FARRUKHABAD
maintenance flows
14000
12000
10000
8000
6000
4000
2000
0
Site EF3 –Kachla Ghat EMC B, 45% MAR
1 2 3 4 5 6 7 8 9 10 11 12
Months
Flow Volume, MCM
maintenance low maintenance high natural total Present

24. 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

25. 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.

26. THANK YOU !THANK YOU !