Analysis of Intra-Storm Suspended Sediment Delivery Processes from Different Tributaries to the Lake Zarivar using Hysteresis Patterns

The behavior of suspended sediment during flood events is not only a function of energy conditions، i. e. sediment is stored at low flow and transported under high flow conditions، but also is related to the variations in sediment supply and sediment depletion. These changes in sediment availability result in so-called hysteresis effects. Therefore، Hysteresis pattern analysis is of great importance in sediment studies in the watersheds. However، their analyses has been rarely considered. In this study، based on the discharge and sediment concentration data collected from 8 storm events occurred during March 2 011 to April 2012، event suspended sediment dynamics of 7 tributaries of the Lake Zarivar watershed was investigated using hysteresis patterns. Based on the fact that all sampling points were not active in all events، about 46 hysteresis patterns were obtained. The analysis of results showed that 16، 13، 11، and 6 events had clockwise، irregular، complex and counterclockwise patterns، respectively. Small tributaries of the Zarivar lake watershed showed the rapid responses to the variation of storm intensity and the most hydrographs of different storms were multi peak discharges and consequently high suspended sediment variations led to different hysteresis patterns. The diversity of patterns suggested that the detailed processes of sediment transport were not only complicated during one event but also varied from event to event. The reasonable and statistically significant relationship (p<0. 05) between suspended sediment yield and peak discharge of each sampling point indicated that the data from all events may be statistically well described by a simple regression equation، regardless of different inter and intra-storm variations of the suspended sediment.