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Ganga Environmental Flow Calculator and its Applications

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Presented by IWMI's Nishadi Eriyagama at training event on the concept and application of maintaining Environmental Flows (EFlows) organized by IWMI in Kathmanu Nepal, on September 29, 2015.

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Ganga Environmental Flow Calculator and its Applications

  1. 1. Ganga Environmental Flow Calculator and its Applications Nishadi Eriyagama Kathmandu, Nepal September 2015
  2. 2. Outline • IWMI Environmental Flow Calculators • Overview of the Ganga Environmental Flow Calculator • Environmental Flow Estimation Method • Example Applications from Sri Lanka • The way forward
  3. 3. 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
  4. 4. 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
  5. 5. 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
  6. 6. Estimation Method Developed by Smakhtin and Anputhas (2006) 0 10000 20000 30000 40000 50000 60000 1972/01 1973/07 1975/01 1976/07 1978/01 1979/07 MonthlyFlow(MCM) Time Natural Flow Time Series 1 10 100 1000 10000 100000 1000000 0.01 0.1 1 5 10 20 30 40 50 60 70 80 90 95 99 99.9 99.99 % Time Flow Exceeded 0 5000 10000 15000 20000 25000 30000 35000 40000 45000 1972/01 1973/07 1975/01 1976/07 Time Natural Flow Duration Curve (FDC) Environmental FDCs Natural Time Series Environmental Flow Time Series ABC A B Spatial Interpolation (Hughes and Smakhtin 1996)
  7. 7. Software at a glance
  8. 8. Example Applications Assess current ecological condition against natural condition Generate potential environmental flow scenarios Mederipitiya Udugama Jasmin Agliya Kotmale Reservoir Talawakelle Peradeniya Polgolla Victoria Reservoir Mallanda Ullapane Mahaweli Gin Ganga
  9. 9. Example - Ullapane Kotmale Reservoir Talawakelle Peradeniya Polgolla Victoria Reservoir Mallanda Ullapane Ungauged Gauged River Mahaweli Gauged
  10. 10. Example – Ullapane Talawakelle Mallanda Peradeniya Polgolla Ullapane Establishing the natural flow Regime (Flow Duration Curve) Kotmale Reservoir Victoria Reservoir Hx 𝐻 𝑥−𝐻 𝑚𝑎𝑙𝑙𝑎𝑛𝑑𝑎 𝐴 𝑥−𝐴 𝑚𝑎𝑙𝑙𝑎𝑛𝑑𝑎 = 𝐻 𝑝𝑒𝑟𝑎𝑑𝑒𝑛𝑖𝑦𝑎−𝐻 𝑚𝑎𝑙𝑙𝑎𝑛𝑑𝑎 𝐴 𝑝𝑒𝑟𝑎𝑑𝑒𝑛𝑖𝑦𝑎−𝐴 𝑚𝑎𝑙𝑙𝑎𝑛𝑑𝑎 1 10 100 1000 0 20 40 60 80 100 Peradeniya Ullapane Discharge(MCM)/month % of Time Flow Exceeded Mallanda
  11. 11. Example – Ullapane 1 10 100 1000 0 20 40 60 80 100 Discharge(MCM/month) % of Time Flow Exceeded Comparison of Current Flow Regime with Environmental Flow Regimes Natural Class A Class B Class C Current 0 50 100 150 200 250 1 2 3 4 5 6 7 8 9 101112131415161718192021222324 Discharge(m3/s) Months from January 1950 Flow Current Natural Class A Class B Class C
  12. 12. Udugama Jasmin Agliya Example - Mederipitiya Ungauged Gauged Gauged Gin Ganga Mederipitiya
  13. 13. Example – Mederipitiya Establishing the natural flow Regime (Flow Duration Curve) Mederipitiya Udugama Jasmin Agliya 1 10 100 1000 0 20 40 60 80 100 Udugama Jasmin % of Time Flow Exceeded Mederipitiya Discharge(MCM)/month
  14. 14. Example – Mederipitiya Generation of Environmental Flow Scenarios 10 20 30 40 50 60 70 80 1 6 11 16 21 Months from january 1980 Natural Class A Class B Class C 10 100 1000 0 20 40 60 80 100 % of Time Flow Exceeded Natural Class A Class B Class C Discharge(MCM/month) Discharge(MCM/month)
  15. 15. Calibrating The Shifts H o w ? 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.)
  16. 16. 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
  17. 17. THANK YOU!

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