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Paper presented at the Seminar on Cascade Irrigation Systems for Rural Sustainability held on 9 th December 2010 at SLFI, Colombo, organized by Plan Sri Lanka. Essential Components of Traditional Village Tank Systems. P.B. Dharmasena. Interceptor. Interceptor ( Kattakaduwa ).
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Paper presented at the Seminar on Cascade Irrigation Systems for Rural Sustainability held on 9th December 2010 at SLFI, Colombo, organized by Plan Sri Lanka. Essential Components of Traditional Village Tank Systems P.B. Dharmasena
Interceptor (Kattakaduwa) • Three land phases (water hole, marshy land and dry upland) • Reduce tank seepage • Prevent entering Na, Mg, Fe into the paddy land • Safeguard the tank bund • A common village garden and agro-forestry system – medicine, fuel wood, timber, fencing materials, farm and household materials, food, fruit, vegetable, fodder • Raw materials for cottage industry • Plant diversity (77 species – 13 species specific to kattakaduwa
Three land phases of Kattakaduwa Wetakeya Gotukola, mukunuwenna, kiriala, Vewel Patabeli, kumbuk, kohomba, divul, mee, amba Pan, kohila, wadakaha, kankun Thal, puwak, milla, teak
Tree species 23 10 Home garden 148 Forest 76 70 34 9 13 21 Interceptor 77
Four phases of the traditional tank Waangilma (High flood phase) Wevthaula (shallow phase) Jalagilma (deep phase) Madakaluwa (dead storage)
Four phases of the traditional tank Waangilma (High flood phase) Wevthaula (shallow phase) Jalagilma (deep phase) Madakaluwa (dead storage)
Four phases of the traditional tank Waangilma (High flood phase) Wevthaula (shallow phase) Jalagilma (deep phase) Madakaluwa (dead storage)
PARTIAL DESILTING CONCEPT • Reduces water losses • Makes upstream area free of water • Reduces salinity in the upstream area • Allows to re-establish gasgommana and perana • Avails water during dry period • Increases cropping intensity
PARTIAL DESILTING CONCEPT Proposed Area (ha) In the past At present Elevation (m) FSL FSL Sill level
PARTIAL DESILTING CONCEPT Catchment area Natural streams Old tank bed Removed sediment New tank bed Tank bund Interceptor
Thisbambe – Buffer zone of hamlet, resting place of buffalo, protection from malaria and wild animals, sanitary activities, nutrient source to paddy field
Kiul-ela Common drainage of paddy tract, disposal of saline water from kattakaduwa, bio-diversity, habitats for predators
Iswetiya – Soil erosion control, prevent sedimentation, acts as a temporary water pond
Godawala– Sediment trap, drinking water for cattle and wild animals
Gasgommana and Peraana • Wind barrier – reduces evaporation • Reduces temperature • Habitat of some species • Fish breeding points • Territory between man and wild animals • Reduce sedimentation