Study on hydrological characteristics of the upper catchment of Selorejo reservoir

Abstract

Selorejo Reservoir as one of the key reservoirs in Brantas system has been intensively managed by Public Corporation of Jasa Tirta I as regard to its roles in supplying raw water for irrigation, generating electricity through a series of hydropower plants, and enhancing the fisheries and recreation activities. Being located in the upper of Konto River, Selorejo Reservoir also receives water from Pinjal River and Kwayangan River with total area of upper catchment of 236 km2. This study is aimed to understand the hydrological characteristics of the upper catchment of Selorejo Reservoir by making use of NRECA and HBV96 models. Based on the monthly basis analysis starting from year of 1999 to 2008, the NRECA model shows that the upper catchment of Selorejo Reservoir has experienced slight changes in soil moisture and groundwater storage since year of 2002. Similar responses also given by HBV96 model for the considered years. The values of Nash Sutcliffe (NS) values obtained for NRECA and HBV96 models are 0.728 and 0.780 respectively. While according to the objective function of Relative Volume Error (RVE), the HBV96 model gives more accurate result compared than NRECA model. Being implemented in duration curve, both models deliver slightly lower stream flow for various probabilities.