Seasonal variations of suspended sediment concentration in rain and snow melting floods
2013
Aghabeigi, Soheyla | Telvari, AbdolRasoul | Mirnia, Khalagh | Feiznia, Sadat | Vafakhah, Mehdi
Sediment concentration in rivers, especially in seasonal ones, is affected by flood situation due to changes of rainfall or snowmelt events. Due to the importance offlooding flows in inundation and the useful age of reservoirs built on seasonal rivers, the study and assessment of this issue seems to be essential. In the present research, suspended sediment concentration variation in spring and autumn floods and runoff from snowmelt in spring, have been studied for Abshine River in EkbatanDam Watershed. Over the forecast period, threestorms in autumn,twostorms in spring andfive snowmelt events were selected and compared. Analyzing226suspended load samples showed its variability in the area. Sediment rating curves in different basetimesshowed different trends. The correlation coefficient (r) were 0.79 and 0.50 for storms and snowmelts and 0.81 for all data, respectively. Also, coefficient and power valueanalysis of sediment rating curve, presented the same erodibilityfor hill slope in both seasons (spring and autumn). Separating falling and rising limbs of flow hydrograph and assessing their effect on discharge explains a better Q-sediment concentration relationship. The hysteretic shape of discharge and sediment concentration had clockwise and anticlockwise form and compound pattern of both forms that reflected the distribution of probable sediment sources throughout the catchment.
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