Udawalawa based irrigation system.
Udawalawa irrigation system
Udawalawa based irrigation system mainly on Walwe river which is around the walawa Mahaweli area. Walawe river basin Sri Lanka has 103 drainage basins out. Walawe river basin is the largest which intersperses both in the Wet and the Dry Zone and has a catchment area of 2442 km2. The upper part of the basin has southern foothills of the Central Highlands with the highest elevation reaching above 2000 m. Southwards the elevation decreases down to the Lowlands of the Dry Zone. The wide elevation range gives annual rainfall amounts that stretch from 1000 mm in the south-eastern parts to over 2500 mm in the upper reaches.
Origin of Walawe River.
Walawe river originates in the northern part of the basin which has 2395 m above sea level, and flows about 100 km southwards and out in the sea by Ambalantota. The headwaters of Walawe generally receive 4500 mm of rain annually. Approximately 50 % of the rainfall received in the basin reaches Walawe River through run-off. The other half has vegetation or dissolves into the air through evaporation. 5.2 Uda Walawe irrigation Cutting across Walawe River which is on the boundary between the Wet Zone of Ratnapura District and the Moneragala District, is the Uda Walawe reservoir. The reservoir has affected by the Northeat Monsoon rather than the Southwest Monsoon. Together with a number of smaller tanks Uda Walawe helps to provide the irrigated cultivations with water.
The reservoir has developed to produce hydropower. Table. The capacity of Uda Walawe reservoir. Two main irrigation canals are connected to the Uda Walawe reservoir. Namely the Right Bank Main Canal (RBMC) and the Left Bank Main Canal (LBMC) (MASL, 2008). These canals pass a number of smaller tanks which have connected to the Walawe River which are all a part of the Uda Walawe irrigation scheme.
Block from Walawe River,
Six blocks come under the scheme; 34 Chandrikawewa, Murawesihena and Angunakolapelessa are the three blocks of the RBMC with 12000 hectare of irrigable land. Sevanagala, Kiriibbanwewa, Sooriyawewa and Mayurapura are within the LBMC. On the left bank 6744 hectare of irrigable land, up to Sooriyawewa, has developed from 1997 to 2003. The most southern part of the LBMC was commenced first in 1999 which was scheduled to be finished in 2003. Subsequently added an extra 5152 hectare of irrigable land to the scheme which is making the LBMC irrigate a total area of approximately 12000 hectare.