Comparison of correction factors for sediment rating equations in rivers of semi-arid and semi-humid regions

With attention to high potential in sediment delivery of semi-arid and semi-humid regions, in this study was prepared sediment-discharge equation for Poldoab Shazand station (Markazi province) with semi-arid climate and Tireh Dorud station (Lorestan province) with semi-humid climate. Then with applying the MVUE, Smearing, QMLE, FAO and β compared the correction amounts of equations for two regions. According to results, the most number of Nash-Sutcliffe criteria was related to FAO with 0.558 in the Poldoab Shazand station and 0.715 in the Tireh Dorud station. Also correction coefficients in the Tireh Dorud station was around 1.7 equal then to Poldoab Shazand station. Due to the high variation of coefficients a and b of equations two stations, as well as an inverse relationship between the two coefficients, it is needed in preparation of sediment rating equation that moreover river flows variable, other parameters related to precipitation specifications and physical properties of watershed can be applied.