Assessment of relationship between important runoff parameters and gully erosion in Darehshahr rangeland watershed

Soil erosion resulted from degradation of vegetation cover and consequent water loss in Iran watersheds is one of the important managerial issues in the country. Studying water resources, soil erosion and effective factors is then very important. Gully erosion also extends in many parts of Iran and its study particularly in view point of sediment yield is therefore a vital task for watershed managers. The present study was taken place in Darehshahr city in Ilam province, Iran, in order to investigate the relationship between sediment yield from gully erosion and runoff parameters viz. runoff peak, specific discharge, runoff depth, time of concentration, runoff volume, and volume to discharge ratio and runoff velocity. For this purpose, 18 axial, frontal and degitated gullies were precisely selected and their morphometric variations were surveyed at the beginning and the end of 5 storm runoff events during November 2005 to January 2006. The important affecting factors were then determined with the help of factor and regression analyses. The results of the study verified non-significant (r<0.239) effects of study runoff factors in sediment yield by gully erosion.