Determination of best sediment estimation model in semi-arid rangelands by using small reservoirs dams sedimentation(case study: daremorid watershed in kerman province)

Empirical models are one of the appropriate tools to estimate the rate of erosion and sediment yield in ungauged basins. Generally, empirical models might be evaluated before any application in other regions. For assessment of MPSIAC and EPM models in Kerman province, 10 small dams were chosen with rangeland use in their upstream. The age of all selected dams were 12 years without any overflow, and all the sediments had been trapped. The deposited materials were determined using reservoir survey and measurement of sediment depth and density. Observed average annual sediment yield (AASY) for each basin was then obtained by considering the age of dams. Results showed that the minimum, maximum and mean AASY for study catchments were 0.6, 16.9 and 6.3 ton/ha/yr respectively. In the next step, AASYs of those watersheds were estimated by surveying and mapping models' factors. The minimum, maximum and mean AASY for the MPSIAC and EPM models were 3.7, 5.7, … and 1.1, 19.8, … ton/ha/year correspondingly. Comparison between observed and estimated sediment means were performed by t-student test. The results demonstrated that there were no significant differences between estimated and observed sediment yield at 95% confidence level. However, the MPSIAC is more accurate due to the smaller relative mean square error (0.09) compared to the EPM (0.18).