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 andsediment estimation one can use statistical and empirical methods. for doing this, land unit map and the map of effectivefactors 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, weapplied gis techniques to estimate erosion and sediment of menderjan watershed at upstream of zayandehrud river incentral part of iran. erosion features of each land unit were defined on the basis of land use, geology and land unit mapsusing gis. the utm coordinates of each erosion type with higher erosion intensities such as rills and gullies wereinserted in gis using gps data. the frequency of erosion indicators of each land unit, land use and sediment yield ofthese indices were calculated. also by using sediment yield changes in watershed outlet (hydrometric station), theeffective parameters in sediment production were identified. the results of this study can be used for more rapid and moreaccurate estimation of erosion than traditional methods. these results can also be used for regional erosion assessment andcan be applied by using remotely- sensed data.