Analysis of the Spatial and Temporal Suspended sediment of Qarahsu Drainage Basin

This study is aimed at estimating suspended sediment load in watersheds using hydro-climatic factors with the intent to determine spatial and temporal variations of sediment yield in Qarah Su drainage basin, Ardebil Province. For this study, data from seven rain gauge and hydrometric stations during a 22-year period were used. The research was based on statistical regression analysis between variables of precipitation, discharge and sediment load using SPSS software, extracting optimal model according to high correlation and acceptable significance.The results indicated very poor correlation between the mean rainfall and mean suspended sediment load in the studied stations. In contrast, discharge showed moderate and significant correlation with the suspended sediment load, which in the best condition,it explained 52% of the precipitation variations. Results of spatial variations showed that Dostbaglu station with average annual sediment load of 1749/79 tons per day had the maximum sediment yield. Lay station with an average annual sediment load of 1/7 ton per day had the minimum sediment yield in the studied basin. Temporal variations showed the highest sediment load rate in April and the in July. Variations in annual sediment load have an increasing trend in Lay and Pole Soltani stations, whereas other stations have a decreasing trend. The discharge trends showed an increasing mode only in Lay station. Meanwhile, with the exception of the Samian station, variations in annual precipitation in the stations showed increasing trend, which has considerable difference with the trends of sediment load and discharge.