Erodibility and sediment yield assessment using EPM model in GIS in parts of Zayandeh-Rud catchments - Heydari basin in north. Shahrekord, Iran

The delivery of considerable sediments into the Zayandeh-Rud dam highlights the study of erodibility of the rock outcrops in Heydari catchment, north. Shahrekord. This basin covers and area about 117.2 square kilometers and is located in the Sanadaj-Sirjan geological belt in south-west of Iran. The EPM and geological models for the erosion index has been used to evaluate the magnitude of the sediment yield in this basin, which is divided into six distinct sub-basins. Sampling on headwaters and subsequent grain-size analysis combined with identification of the lithology of the grains on different sieves gave the data needed for the calculation of erodibility index of the different lithological units. Using the EPM parameters, the intensity of sediment yield has been calculated and compared to the annual sediment yield. Results show that the erosion index for a single lithologic unit is variable depending on lithology, slope and vegetation cover. However, the erosion index for a lithologic unit in different parts of a basin is much close to the real and observed situation.