Impact of Land Use Change to Dependable Flow in Kuncir River, Nganjuk District, East Java

Abstract

Currently, Kuncir River is a source of irrigation water in the southern of Nganjuk District. The potential ofKuncir River was assessed by measuring the dependable flow as an indicator of water supply for irrigatedareas. The objective of this study was to estimate the river discharge and its dependable flow for irrigationfrom Kuncir River in Nganjuk District. River discharge data was collected from Kuncir River, rainfall data wascollected from Nganjuk District, East Java and climate data was collected from climatology station of BadanMeteorologi Klimatologi dan Geofisika (BMKG) Sawahan, Nganjuk. There were two major steps on thisstudy which were model development and model simulation using SWAT after calibration and validation.Model simulation showed NS value of 0.67 with mean daily flow of 7.15 m3 s-1. Based on land use changescenario, the conversion of 50% on forest and 50% on range-grasses into agriculture land could increase3.1% and 2.5% of average river discharge, respectively