Ganga Environmental Flow Calculator and its Applications
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Transcript of Ganga Environmental Flow Calculator and its Applications
Ganga Environmental Flow Calculator and its Applications
Nishadi Eriyagama
Kathmandu, NepalSeptember 2015
Outline• IWMI Environmental Flow Calculators
• Overview of the Ganga Environmental Flow Calculator
• Environmental Flow Estimation Method
• Example Applications from Sri Lanka
• The way forward
IWMI Environmental Flow Calculators
• Global Environmental Flow Calculator (GEFC)– Global coverage; gridded flow data
• Ganga Environmental Flow Calculator– Ganga Basin; location specific flow data
• Sri Lanka Environmental Flow calculator– Sri Lanka; location specific flow data
Ganga Environmental Flow Calculator
?
Desktop tool currently based on hydrology
Estimates flow for 6 Environmental Management Objectives (Environmental Management Classes A-F)
Uses environmental flow estimation method of Smakhtin & Anputhas (2006)
Provides 149 simulated flow time series from SWAT and WEAP models. User input also possible
Method based on constructing a Flow Duration Curve (FDC) from monthly “natural” flow time series
Environmental Management Classes
A Minor modifications Protected rivers
B Slightly modified Water supply/irrigation development allowed
C Habitat, biota disturbed, but basic functions intact
Dams, diversions, reduced water quality
D Large changes in habitat, biota and basic functions
Significant, clearly visible disturbances by regulation
E Habitat diversity declined. Only tolerant species exist
High population density and extensive development
F Total loss of natural habitat and biota
Unacceptable status
Estimation Method Developed by Smakhtin and Anputhas (2006)
1972/01
1972/02
1972/03
1972/04
1972/05
1972/06
1972/07
1972/08
1972/09
1972/10
1972/11
1972/12
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1973/03
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1973/05
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1973/07
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1973/11
1973/12
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1974/03
1974/04
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1974/06
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1974/08
1974/09
1974/10
1974/11
1974/12
1975/01
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1975/07
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1975/09
1975/10
1975/11
1975/12
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1976/02
1976/03
1976/04
1976/05
1976/06
1976/07
1976/08
1976/09
1976/10
1976/11
1976/12
1977/01
1977/02
1977/03
1977/04
1977/05
1977/06
1977/07
1977/08
1977/09
1977/10
1977/11
1977/12
1978/01
1978/02
1978/03
1978/04
1978/05
1978/06
1978/07
1978/08
1978/09
1978/10
1978/11
1978/12
1979/01
1979/02
1979/03
1979/04
1979/05
1979/06
1979/07
1979/08
1979/09
1979/10
1979/11
1979/12
0100002000030000400005000060000
TimeMon
thly
Flo
w (
MCM
)
Natural Flow Time Series
0.01 0.1 1 5 10 20 30 40 50 60 70 80 90 95 99
99.9
99.99
110
1001000
10000100000
1000000
% Time Flow Exceeded
1972/01
1972/02
1972/03
1972/04
1972/05
1972/06
1972/07
1972/08
1972/09
1972/10
1972/11
1972/12
1973/01
1973/02
1973/03
1973/04
1973/05
1973/06
1973/07
1973/08
1973/09
1973/10
1973/11
1973/12
1974/01
1974/02
1974/03
1974/04
1974/05
1974/06
1974/07
1974/08
1974/09
1974/10
1974/11
1974/12
1975/01
1975/02
1975/03
1975/04
1975/05
1975/06
1975/07
1975/08
1975/09
1975/10
1975/11
1975/12
1976/01
1976/02
1976/03
1976/04
1976/05
1976/06
1976/07
1976/08
1976/09
1976/10
1976/11
1976/12
1977/01
1977/02
1977/03
1977/04
1977/05
1977/06
01000020000300004000050000
Time
Natural Flow Duration Curve (FDC)
Environmental FDCs
Natural Time Series
Environmental Flow Time Series
A B C
A
B
Spatial Interpolation (Hughes and Smakhtin 1996)
Software at a glance
Example Applications
Assess current ecological condition against natural condition
Generate potential environmental flow scenarios
Mederipitiya
Udugama
Jasmin
Agliya KotmaleReservoir
Talawakelle
Peradeniya
Polgolla
Victoria Reservoir
Mallanda
Ullapane
Mahaweli
Gin Ganga
Example - Ullapane
KotmaleReservoir
Talawakelle
Peradeniya
Polgolla
Victoria Reservoir
Mallanda
Ullapane Ungauged
Gauged River Mahaweli
Gauged
Example – Ullapane
Talawakelle
Mallanda
PeradeniyaPolgolla
Ullapane
Establishing the natural flow Regime (Flow Duration Curve)
KotmaleReservoir
Victoria Reservoir
Hx
=
0 10 20 30 40 50 60 70 80 90 1001
10
100
1000
Peradeniya
Ullapane
Disc
harg
e (M
CM)/
mon
th
% of Time Flow Exceeded
Mallanda
Example – Ullapane
0 10 20 30 40 50 60 70 80 90 1001
10
100
1000
Dis
char
ge (M
CM
/mon
th)
% of Time Flow Exceeded
Comparison of Current Flow Regime with Environmental Flow Regimes
Natural Class A
Class B
Class C
Current
1 29 57 85 1131411691972252532813093373653934210
50
100
150
200
250
Months from January 1950
Disc
harg
e (m
3/s)
Flow
(M
CM
)
Current Natural Class A
Class B
Class C
Udugama
Jasmin
Agliya
Example - Mederipitiya
Ungauged
Gauged
Gauged
Gin Ganga
Mederipitiya
Example – Mederipitiya Establishing the natural flow Regime (Flow Duration Curve)
Mederipitiya
Udugama
Jasmin
Agliya
0 20 40 60 80 10010
100
1000
Udugama Jasmin
% of Time Flow Exceeded
Mederipitiya
Disc
harg
e (M
CM)/
mon
th
Example – Mederipitiya
Generation of Environmental Flow Scenarios
1 6 11 16 2110
20
30
40
50
60
70
80
Months from january 1980
Natural Class A Class B Class C
0 10 20 30 40 50 60 70 80 90 10010
100
1000
% of Time Flow Exceeded
Natural Class A
Class B Class C
Disc
harg
e (M
CM/m
onth
)
Disc
harg
e (M
CM/m
onth
)
Calibrating The Shifts
How?
Indicators based scoring system eg: Smakhtin et al. (2007) for Indian rivers (range, uniqueness, diversity of aquatic biota, degree of flow regulation and fragmentation etc.)
Link the phase of development of the river (as in Molden et al. 2001) to flow regime and have differential shifts within each phase “Development”, “Utilisation”, “Allocation”
Statistical approach: link human basin modifications and flow alterations eg: Homa et al. (2013) for rivers in the USA (population, road density, number of dams, dam storage etc.)
The Way Forward Provide planning level guidance for environmental flow estimation
“Calibrate” the FDC shifts to suit location-specific conditions
Incorporate an algorithm to estimate flows at ungauged sites
repository of all available observed/simulated flow time series in a region/country
THANK YOU!