THE EFFECT OF LAND USE CHANGE TO THE DEPTH AND AREA OF INUNDATION IN THE BANG SUB-WATERSHED-MALANG-INDONESIA

More than 50% of East Java Province area has the high potential flood disaster, one of them is the Bang sub-watershed. The aim of this paper is to analyze the area and depth of inundation on the river of Bank sub-watershed due to the land use change in surrounding it. This study is located in the Bang sub-watershed, Tamban coast, Tambakrejo village, Sumbermanjing Wetan district, East Java Province-Indonesia. The methodology consists of predicting the inundation area and flow pattern in the Bang river by using the software of HEC-GeoRAS (Hydrologic Engineering Centre and River Analysis System) version 3.1 which compiling the two main software that are HEC RAS version 4.1.0 and Arc View GIS version 3.3. The result shows that the maximum inundation is 4.99 km2 on the return period of 50 years based on the land use on 2010. The land use change from 2001 to 2010 indicates that the increasing inundation area is 0.4%, however, the inundation depth is increasing 0.5%.