Perubahan Lahan dan Debit Sungai di DAS Ciasem Subang Jawa Barat

Abstract

The changes of surface run off and river discharge caused by landuse changes, could be estimated by watershed hydrology models. Soil and Water Assessment Tool (SWAT) model is a hydrology model that developed to predict effect of land use not only to water yield, but also sediment, pesticide contents, and chemical result of agriculture. Previous research of SWAT model application in Ciasem sub-watershed (5 659.6 Ha) by using global and local data show that the prediction average monthly discharge was appropriately match with measured average with the values of R2 and NS were > 0.51 and > 0.74 respectively. This research applied SWAT model to predict river discharge changes due to landuse change in the entire Ciasem watershed (67 794.8 ha). The purpose of this research is to predict changes in discharge due to changes in land use in the Ciasem watershed using SWAT model. Landuse changes in 2006-2011 occurred at forest plants being mixture of dryland farming, were 696.5 ha and forest plants being farms, were 131.8 ha. Simulation result of run off and discharge in landuse 2006 and 2011 and input climate 2006 showed it increase the runoff by 0.4 mm/month (4.8 mm/year) and discharge by 0.05 mm/month (0.6 mm/year). Land use simulation which changes mixture of dryland and dryland farming become forest plants reduce run off by 1.3 mm/month (15.6 mm/year) and discharge by 0.7 mm/month (8.4 mm/year) especially during wet months and increased discharge in dry months.