the tank cascade system and the contribution of ground water to the livelihoods of the dry zone in...
DESCRIPTION
IWMI’s Yoshiaki Inadi takes a closer look at Sri Lanka’s water storage reservoirs, locally known as “tanks”, and the growing importance of “agro-wells” for accessing groundwater.TRANSCRIPT
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A water-secure world
The Tank Cascade System and the Contribution ofGround water to the Livelihoods of the Dry Zone in Sri Lanka
Yoshiaki Inada6th November 2013INWEP 10th Steering meeting andSymposium at Centara DuangtawanHotel in Chiang Mai, Thai Land
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Today’s presentation
1.Review the past tank cascade system and ground water recharge studies in IWMI
2. Agro-well development due to high ground water level
3. Multiple benefits of high ground water level derived from irrigation project
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Rainfall, Agro ecological zone
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Climate and cultivation season
• Climate seasons
• First inter monsoon – March to April
• Southwest monsoon – May to September
• Second inter monsoon – October to November
• Northeast monsoon – December to February
• Cultivation Season
• Yala: March to September – less rain in dry zone area
• Maha: October to February – major rainy season in dry zone area
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Location of the study site and tankdistribution in dry zone
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Average Month Total Rainfall & Evaporation
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Water Balance and GroundwaterStudies in Tank Cascade
• Tank balance model in Thirappane Cascade System (TCS)
• Itakura 1995
• Shinogi 1997
• Shanthi 2002 • Sub-watershed balance (on going) – 2013 Ministry of Water Resource Management/Water Resource Board of Sri Lanka • JIRCAS conducting a utilization of water balance model study in Thirappane (on going) • Cascade study – upper Yan Oya - Matsuno -1996
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Thirappane Cascade
Located at Anuradhapra district in the North Central province
6 interlinked small tanks are situated 8 km between top and bottom tanks
Jun Itakura’s initiated Study in 1991
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Tank water balance in Shinogi’s study
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Cross Sectional View of Meegassagama Tank (Shanthi’s study)
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Seepage and percolation values found in the Studies
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Agro-well development around tank
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Uda Walawe Irrigation and Resettlement Project
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Economic benefits on rechargingground water(home-garden produce)
Total value of US$14.4 million/year (Molle, F; Renwick, M 2005)
13,000 ha (satellite images) Amount(sampling survey) Value(local market price) Fruit value US$8 million/year Timber value of US$6.40 million/year
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Economic benefits on rechargingground water(domestic water supply)
• value of drinking water is estimated at US$0.14 million/ year. (Molle, F; Renwick, M 2005)
average water supply cost of 15 Rs/m3 (recent communal water supply projects) average current usage of 20 liter/person/day and population estimate of 120,000 (Irrigation Department)
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Multiple benefit derived from the Uda Walawe Project
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Thank You