Application of Gully and Rill Erosion Indicators for Estimating Soil Loss Using GIS Techniques

The problems of land degradation and soil loss are among the major problems of watersheds in Iran. For erosion and sediment estimation one can use statistical and empirical methods. For doing this, land unit map and the map of effective factors should be prepared. For erosion and sediment estimation one can use statistical and empirical methods. However, these empirical methods are usually time consuming and do not give accurate estimation of erosion. In this study, we applied GIS techniques to estimate erosion and sediment of Menderjan Watershed at upstream of Zayandehrud River in central part of Iran. Erosion features of each land unit were defined on the basis of land use, geology and land unit maps using GIS. The UTM coordinates of each erosion type with higher erosion intensities such as rills and gullies were inserted in GIS using GPS data. The frequency of erosion indicators of each land unit, land use and sediment yield of these indices were calculated. Also by using sediment yield changes in watershed outlet (hydrometric station), the effective parameters in sediment production were identified. The results of this study can be used for more rapid and more accurate estimation of erosion than traditional methods. These results can also be used for regional erosion assessment and can be applied by using remotely- sensed data.