Measuring and estimation of suspended sediment variation using sediment rating curve approach in Mereg River

As a major component of hydrological, geomorphological, and ecological functioning of rivers, suspended sediment has been identified as the leading direct cause of river instabilities. Therefore, recognizing the variability of rivers is essential to manage water resources and environmental issues. As a result, 5 storms were sampled and analyzed for 4 months in Mereg watershed from 2015 to 2016. Sampling was taken in 2 hours interval and suspended sediment concentration was obtained in the laboratory by filtration method. Estimation of temporal variation of suspended sediment during storm was carried out using sediment rating curves. Different approaches were used to prepare sediment rating, including hysteresis pattern, hydrological and seasonal separation. Measured floods have the peak flows from 1.38 to 49.40 m3/s covering a suitable range of low to high peak flows in this river. Moreover, the peak suspended sediment concentration measured in these storms was from 1 to 15.2 g / l. The average suspended sediment load in the study period was 15,919 tons. Measurement of suspended sediment during winter and spring showed that the generation and transportation of suspended sediment in spring is higher than winter in the studied watershed. The fitted relationships on all rating curves was valid and had a determine coefficient higher than 0.5 and estimated error below 50%. The results show that rating curve can provide acceptable estimate of suspended sediment load in the Mereg River without the need for classification or segmentation of rating curve.