APPLICATION OF SIMPLE HYDROLOGIC MODEL FOR PREDICTING THE EFFECT OF WATER CONSERVATION MEASURES AT THE UPPER WATERSHED OF DAM

Chandra Setyawan Faculty of Agricultural Technology, GadjahMada University, Yogyakarta. chandra.tep@ugm.ac.id

SahidSusanto Faculty of Agricultural Technology, GadjahMada University, Yogyakarta. s_susanto@ugm.ac.id

A B S T R A C T

The recent condition of degraded land at the upper watershed of dam in Java is increasing significantly. It implies on sedimentation problem flowing to the dam. The aim of study was directed to apply a simple methodfor simulating the effects ofwater resource conservation measures. Hydrologic model of Mock was proposed for the study. The model is basically rainfall-run-off relationship containing three tanks arranged in vertical position. Finding optimal six parameters in the model were conducted by trial and error. Two degraded upper watersheds of dam at Central Java were used as the study.This area study falls into tropical monsoon region.The results show that the model is sensitive enough to predict hydrologic regime in the upper watershed of dams studied. The modelwasthen used to simulate the effects of water resource conservation measures applied in the upper watersheds. The simulations were directed to design optimal vegetation landscape in the form some realistic scenarios of land use pattern.Comparing with the existing condition, the simulation results showed that they give significantly effect in reducing surface run off coefficient (from 10% to 20%), sedimentation (15%20%), increasing water resources availability (5%-15%).

Key words: hydrologic model, water resource conservation measures, realistic scenarios of land use pattern