Programme OS5e Multiple and multisector
Water resource allocation modelling to harmonise supply and demand in
the Malaprabha catchment, India
Author(s): Biju George, Hector M Malano, Brian Davidson
Department of Civil & Environmental Engineering, University of Melbourne, Australia
Tel: ++61-3-83446876, email: email@example.com
Keyword(s): Water allocation, modeling, Malaprabha, Krishna.
Session: OS5e Multiple and multisector
The 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.