Analysis of Temporal Variations for the Suspended Load Transport in the Marboreh River, Darreh-Takht, Lorestan Province, Iran

Clarification of suspended load (SL) supply variations at different temporal scales is essential to provide a logical management program. In this study, the SL transport variations were investigated at different time scales in the Marboreh River, Darreh-Takht, Lorestan Province, Iran. The four seasonal, seasonal threshold, annual and land use period approaches were analyzed using statistical methods based on the collected data from 1971 to 2016. The seasonal threshold runoff was determined using the best statistical distribution for the return period of 2 years, and the SL concentration-runoff relationships were prepared for large and small events. The land use map was prepared using remote sensing data for the years 1977 and 2016. According to the results, supply and SL transport capacity were high in the large events of spring, when the slope of the sediment rating curve is 1.469. The supply and SL capacity for large events of the autumn was higher than that of the winter. In the study period, although the land use change from rangeland to dry-farming was observed, the impact of other human activities including dam construction on the tributaries has caused a decrease in the mean SL transport, corresponding with the daily runoff in autumn, winter and spring.