Abstract

One of the major steps in watershed studies including erosion and flood modeling is to identify and extract the physical parameters of the watershed. In traditional methods, these parameters based on their significant roles in simulating hydrological models are extracted using topographic maps. Through the recent years, with the development of earth observation technology, free digital elevation model become available such as SRTM and ASTER data. Spatial resolution is one of the main characteristics in surveying details from geographical features. A wide number of studies have been conducted to extract the physical parameters of watershed using SRTM data (Shuttle Radar Topography Mission) in different regions. In this study, ASTER elevation data was used to delineate watershed boundaries and physiographic parameters of Kardeh watershed. It was then compared with then compared with the derivatives from cartographic products. Based on the correlation coefficient index, it was found that DEM obtained from ASTER data provides a proper capability in determining the watershed boundaries, area, time of concentration and dranage network of the watershed. However, there is a significant inconsistency in estimating the average slope of sub-basins and the waterways’ slope. Investigating the results for each of the sub-basins, it can be concluded that the DEM produced by ASTER is not appropriate for modeling watershed in areas with a slope of more than 35%.

Keywords

ASTER, SRTM, Kardeh watershed, GIS, Remote sensing