Investigation of susceptibility to erosion of rock formations using erosion index in Ziarat watershed

Soil erosion is one of the major current environmental issues. Identification of main erosion sources can be a suitable answer to this issue and an appropriate preliminary assessment for further soil erosion prevention measures. In order to reduce anticipated loss to downstream facilities and farmlands in the Ziarat watershed, the relationship between channel sediments and upstream lithological units as sediment sources was assessed employing erosion index. The aim of the current study is to find lithological sources of channel sediment materials and accordingly to determine the contribution of each lithological unit in erosion process. To this end, first, sediment samples were collected through field surveys and then sieved. After that, 100 sediment grains (particles) were picked from each sample to identify mineral properties using binocular method. After measuring three mineral properties namely genus, the number of minerals and grains, the corresponding source units were identified, then the erosion index for each unit was calculated and finally the susceptibility of lithological units to erosion was mapped. Accordingly, the study area were classified into four susceptible classes including very highly susceptible to erosion with an area of 23.23%, followed by highly susceptible (24.05%), lowly susceptible (9.07) and very lowly susceptible (43.65) areas.