Impact of Land Use Changes on Sediment Yield in Mandarijan Watershed Basin

Soil conservation and sediment yield prevention is necessary for preservation and rehabilitation of renewable natural resources and integrated development of watersheds. The rate and type of sediment yield is generally a function of climatic conditions, topography, soil and land use characteristics out of which the importance of land use because of effective role of human is more than others. In the present study, the relationship between land use changes and sediment yield was studied in Manderijan watershed located in upstream of Zayandehrood dam basin covering an area about 23000 ha. The precipitation and the sediment data belonging to the period of 1979 to 2002 were respectively collected from Chadegan climatological and Manderijan hygrometry stations. The satellite images of MSS 1979, TM 1990, TM 1998 and ETM 2002 were also applied to map land use during study period. The relationship between sediment yield and annual precipitation changes were evaluated using five-years moving average and regression analysis. The assessment of relationship between land use changes and sediment yield was also made using regression equations for the periods corresponded on the time of available satellite images. The results of the study revealed that despite of significant variation in annual precipitation at the confidence level of 99%, it’s controlling role on sediment yield was found to be low owing to inconsistency of changes trend and their non synchronous variations. The analysis of regression equations was also verified the significant relationship in cubic form between irrigated agricultural land use and sediment yield with high determination coefficient of 0.99 and low estimation error of 12%.