Comparison of Conventional Methods for Estimation of Suspended Sediment Load of Karkheh River by Gene Expression Programming Approach

Estimation of suspended sediment load of rivers due to its impact on designing and management of water structures is an important factor in water engineering, hydraulic and environment. Several attempts have been made up to now by the researchers to exact determine the suspended sediment load, for example, the establishment of relation between sediment discharge and flow discharge can be referred. The problem of this conventional method is its uncertainty. So, a number of researchers have been attempted to estimate the suspended sediment load by using intelligence methods and evolutionary algorithms. In the present research, Gene Expression Programming (GEP) was used to predict the suspended sediment load of Jelogir and Payepol stations located at the upstream of Karkheh reservoir dam. The results have been compared with sediment rating curve and FAO methods results. So, daily stream flow, suspended sediment discharge and rain height corresponding from 1986-2012 were collected and used. For this, two scenarios were defined for GEP performing. The first one has been performed by using daily stream flow and suspended sediment discharge data. The second one used the rain height information of catchment, too. The results showed that the second scenario was more accurate rather than the first one. The comparison results of test period indicated that the GEP has decreased the root mean square error (RMSE) and mean absolute error (MAE) around 91% and 94% for Jelogir station and 60% and 71% for Payepol station in relation to USBR results. Also, the results of test period denoted that GEP has decreased the RMSE and MAE around 92% and 96% for Jelogir station and 85% and 95% for Payepol station compared by FAO results.