Quantity assessment of water erosion intensity using regional model of erosion and sediment yield (Case study: Nir watershed, Ardebil)

The aim of this research is to describe the development of a methodology based on present knowledge and available data for evaluation of water erosion behavior and risk as well as modeling and estimation of soil erosion، which is compatible for other similar areas of Iran. Accordingly، the conducted research was based on four major types of water erosions including: sheet، rill، channel and riverbank which have considerable role on sediment yields of Baleghli Chay Watershed، Ardebil Province، were separately and spatially studied. In order to determine the inter-effects of effective factors، the study was conducted using stepwise multivariate statistical tests. For each erosion type، an individual model was then presented. In the next step، after determining of relations between sediment yield and environmental factors (fixed & variable) through statistical analyses and selecting of effective factors on erosion and sediment yields، was created an empirical structure for modeling erosion and sediment yields based on MPSIAC erosion model. In formulation of the new model، were used of eight effective factors on erosion in the area. These factors are susceptibility of geological formation، soil erodibility، rainfall erosivity، runoff erosivity، topography، hydrographic drainage، Normalized Difference of Vegetation Index (NDVI) and field conditions of erosion features. In the presented model، with summation of the scores of mentioned eight factors، obtains the M value، which can estimate the amount of erosion and sediment yields of the area، using exponential formula between sediment yield and M values. In addition، in order to obtain the confidence of presented model، it was used in «Nir» catchment for evaluation the precision. The results showed 11 percent difference. With accepting of this error value، the water erosion hazard map of the area was provided and presented using new model.