Abstract: Today, incorrect use of lands and land use changes,
excessive grazing, no suitable using of agricultural farms, plowing on
steep slopes, road construct, building construct, mine excavation etc
have been caused increasing of soil erosion and sediment yield. For
erosion and sediment estimation one can use statistical and empirical
methods. This needs to identify land unit map and the map of
effective factors. 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 Zayandehrud river in center of
Iran. Erosion faces at each land unit were defined on the basis of land
use, geology and land unit map using GIS. The UTM coordinates of
each erosion type that showed more erosion amounts such as rills and
gullies were inserted in GIS using GPS data. The frequency of
erosion indicators at each land unit, land use and their sediment yield
of these indices were calculated. Also using tendency analysis of
sediment yield changes in watershed outlet (Menderjan hydrometric
gauge station), was calculated related parameters and estimation
errors. The results of this study according to implemented watershed
management projects 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 used for remote
sensing image processing.