Watershed Erosion Analysis (Case Study of Citarum Upstream Watershed)

Abstract

This paper presents the results of the study in partial yearly erosion rate changes, and a simulation of land use according to the pattern space. Watershed ecosystem changes are represented by the modification of land cover and adapted to the spatial conditions. The area studied is the Citarum Upstream Watershed. This study is part of a dissertation which aims to get the value of the condition of soil erosion in a few years and landscaping scenarios in the upstream subCitarum most optimal, so that the reservoir can function properly in accordance with the design life of the reservoir. Analysis was conducted using soil erosion modeled with USLE using GIS models. This analysis provides the form of a map of soil erosion in the study area spatially. In order to use this model for estimating the value of USLE and the actual distribution of soil erosion in a river basin, the approach used is to use a GIS system, where it needs information related to spatial distribution of each parameter USLE. Various spatial characteristics of each USLE parameters obtained from maps available digitally inserted in the form of thematic maps and overlays in the GIS system. Grid cell system is available on further functions significant in GIS, where for each grid cell on the map overlay can be obtained by the value of the rate of erosion per unit area of grid cell is then converted to the rate of erosion per square kilometer. Depiction of the results of the erosion rate map using the USLE method-based Arc-GIS of the obtained values shows that tert erosion increases with land-use changes that occur. The increased is extreme enough that the 4 year increased almost 50% from 6.4 million ton/year in 2006 to 31 million ton/year in 2010. The simulations performed the pattern space Citarum River Flows Regional Plan and obtained sediment 4.36 million ton/year.