QUANTITATIVE GEOMORPHOLOGY OF CIPANCAR WATERSHED AND THE IMPLICATION FOR FLOOD RISK

Abstract

Cipancar watershed is located in Sumedang, West Java, Indonesia. The purpose of this research was to determine the flood risk of the Cipancar watershed in Sumedang area through quantitative geomorphology approach, namely watershed morphometry. Elevation and stream network data used were obtained from a digital elevation model and topographic map using Map Info and Global Mapper software. The morphometric parameters used in this research consist of drainage density, drainage texture, Form factor, ratio of elongation, and ratio of circularity. The research area consists of hills, elongated hills, volcanic cone, and plains. It also consists of radial, subdendritic, and subparallel drainage pattern with the dominance of quaternary volcanic rocks. Cipancar watershed has 15 subwatersheds with predominantly very coarse-intermediate texture and very elongated-elongated basin shape. Only the Cpc_09 and Cpc_10 watersheds have oval-circular basin shape. Rainfall conditions that are not too high do not have a significant effect on the potential for flooding. The research area can be classified into very low to moderate flood risk. The very low-low flood risk is located in the upstream of the Cipancar watershed such as Leles, Cikandung, Leuwigoong, Cicalengka, and South Sumedang districts; and some areas of Kadungora, Cibiuk, Balubur Limbangan, and Selaawi districts. The low-moderate flood risk is located in the middle to downstream of the Cipancar watershed such as some areas of Kadungora, Cibiuk, Balubur Limbangan, and Selaawi districts. The results indicate that the quantitative geomorphology can be used to determine the flood risk in a particular area.