Preparing the Map of Erosion Hazard and Sedimentation in Dez Watershed by Remote Sensing and GIS

Document Type : Original Articles


Department of Remote Sensing &GIS, Faculty of Earth Sciences, Shahid Beheshti University, G.C.


Regarding the importance of water sources in Iran, it is necessary to protect better water bodies such as reservoirs. The most efficient way of conserving water sources is to apply proper management to decrease erosion and sedimentation. The first step of this process is to be aware of sediment yield and identify erosion hazard areas in upper reach of reservoirs. The present study is the preparation of a map of erosion hazard and sedimentation in Dez watershed (area: 17320 km2) which is to be applied in the rehabilitation project of Dez dam. The inaccessible location and the fact that covers a wide area have made the use of satellite images inevitable. In this study, after examining several erosion and sedimentation modeling methods, the PSIAC - with 9 effective parameters - was selected; it is an empirical model in itself. In order to prepare the first series of data, IRS satellite data, Landsat ETM+, basic maps, the Arial photos, helicopter flights and also field checks were all applied. A calibration model with the data achieved from reservoir studies, and taking account of local characteristics of the area, prepared the opportunity to identify and classify erosive zones with GIS. The results which are presented as maps and erosion statistics, not only identify hazardous erosive areas, but also open a new horizon in the field of watershed management and sediment control by having a special outlook towards executive priorities. Keywords: Erosion, Sedimentation, Remote Sensing, GIS, Dez Dam