IWRA Proceedings

AbstractThe effective management of available water in the semiarid regions has increased in importance, due to limited water availability. With growing scarcity and increasing inter-sectorial competition for water the need for efficient and sustainable water allocation policies has also become more important. Finding ways to meet the competing demands, while also achieving positive economic and environmental outcomes, requires the aid of modeling tools to analyze the impact of alternative water allocation policy scenarios. The main aim of this paper is to analyse alternative allocation scenarios in the Malaprabha subbasin, which forms part of the Krishna Basin. Malaprabha River has a catchment area of 11,549 km2 that accounts for 5 percent of the Krishna basin. The catchment area of the sub-basin lies entirely in Karnataka state. It has diversified hydro-climatic zones ranging from humid (annual rainfall - 3047 mm) to semi-arid (annual rainfall - 447 mm) with an average annual rainfall of 766 mm. The 75% dependable flow is 1,857 Mm3 and is declining over years due to reduced rainfall and upstream catchment development. The basin has predominantly agriculture and drinking water demands. The basin serves the drinking water demand of 3 million people in three districts and primarily to major twin cities, Hubli and Dharwad. The demand for water in the Malaprabha catchment will change in the next twenty years due to population growth and changes that occur in different sectors. Historical hydrologic analysis and stream flow simulation were assessed using a monthly conceptual rainfall-runoff model SYMHYD. The Resource Allocation Model (REALM) was used to build the water allocation model and analyse alternate policy scenarios and investigate possible water allocation options. These are used to investigate historic, current and future developments in water demand in the catchment. The paper presents a detailed analysis of security of supply for the main water users in the basin: agriculture, urban and industry, and in-stream requirements. The results highlight the intense competition for water between the alternative uses. The impact of proposed inter-basin import of water into the catchment is also analysed.