Site Suitability Analysis for Reservoirs in Suriyawewa by Using GIS Techniques

Abstract

Sri Lanka receives an average rainfall varying regionally from 900 mm to 6000 mm. Due to the unequal rainfall distributions over the island, Sri Lanka is traditionally divided into three climatic zones, namely Wet Zone, Dry Zone, and Intermediate Zone. The Dry Zone of the island which receives less than 1750 mm of average annual rainfall occupies two thirds of the island and faces water stress conditions periodically. Districts such as Monaragala, Puttalam, Kurunegala, Ampara, Badulla, Hambantota are some of the highly affected districts by these conditions. Hambantota District seems to be a severely affected area on the basis of surface water availability. With the ongoing development projects in the District, the demand for water in the area will increase within the next few years. In this work, Suriyawewa Divisional Secretarial area of the Hambantota District was selected as the research area considering its average climatic conditions and location within Hambantota District, and the methodology adopted here can be generalized to the whole District. Terrain of Suriyawewa area was analyzed hydrologically, and the most suitable catchments to construct reservoirs were found, by using GIS techniques. The selected catchments were then analyzed with soil data and drainage characteristics to select the most suitable locations to construct new reservoirs in the area. Finally the locations are field verified.

Keywords: Catchments, GIS, Hambantota District, Reservoirs, Water scarcity