Simulation of Land Cover Change Impacts on Discharge and Sedimentation in Merawu Catchment, Indonesia

Watershed Laboratory, Department of Forest Resources Conservation, Faculty of Forestry Universitas Gadjah Mada, Yogyakarta 55281, Indonesia

^* Corresponding author: marhaento@ugm.ac.id

Abstract

Merawu Watershed is the upstream part of Serayu Watershed whose outlet is in Mrica Reservoir, Banjarnegara Regency. The capacity of Mrica reservoir continues to experience an increase in sedimentation from year to year, one of the main causes is the high erosion in Merawu Watershed. This study aims to determine the effect of changes in land cover on discharge and sedimentation in Merawu Watershed. Land cover changes were analyzed historically from maps from 2006 and 2022. The Merawu watershed hydrological model was built using the SWAT model and calibrated using the SUFI-2 algorithm. The effect of land cover changes was calculated by comparing the simulation results with land cover data from 2006 and 2022. The analysis of land cover changes shows that the Merawu Watershed experienced a decrease in secondary forest and cultivated land. The built SWAT model produced an R² value of 0.6 and an NSE of 0.55 for calibration and showed an R² value of 0.71 and an NSE of 0.69 during validation. From the simulation results the changes in land cover that occurred had an impact on an increase in the average daily discharge and sedimentation of 294.82% and 662.47%.