Regional modeling of relationship between sediment yield and vegetation cover in Sabalan mountain catchments

The knowledge about spatial relationships of vegetation with sediment yield (S.Y) in watersheds is essential for optimal controlling and managing of water and soil resources. The purpose of this study was to recognize and determine the relationship between vegetation cover and annual S.Y of Sabalan catchments, N.W Iran. In this regard, the possibility of presentation of regional S.Y estimation models based on correlation and regression analysis were considered. Independent variables include average, minimum and maximum NDVI (Normalized Differential Vegetation Index), extracted through the processing of Landsa.t 8 satellite imagery in the ENVI environment. The dependent variable, which was the annual S.Y, was obtained through calculations on sediment load data of 10 sample hydrometric stations. Results of correlation test showed that there was a strong and significant relationship between the average NDVI and the annual S.Y in the catchments (r = -0/758). This inverse relationship emphasizes the importance and apparent role of vegetation in reducing sediment production and transporting in the region. Moreover, the results of regression tests showed that is possible to present the regional estimation models regards to annual S.Y by fitting linear, quadratic and power functions. In this regard, the quadratic model has the highest performance and explain 75% of the annual S.Y variance. The linear relationship was also able to explain 57% of the annual sedimentary variance.