Runoff-sediment dynamics under different flood patterns in a Loess Plateau catchment, China

Investigating the suspended sediment dynamic is useful for gaining a more comprehensive understanding of runoff and sediment yield process. The study analyzes the sediment flow behavior in relation to the flood patterns in the Xichuan River catchment on the Loess Plateau. Based on 23-year hydrological data collected from Zaoyuan hydrological station and K-medoids clustering method, one hundred and twelve flood events data were classified into four flood patterns. The hydrologic features of different flood patterns exhibit significant differences. The values of the mean runoff depth, the mean flood duration, and the mean flood peak discharge decreased as the following order: Pattern A > Pattern C > Pattern D > Pattern B. Each flood pattern results in differing levels of the event sediment yield (SY), the SY of Pattern A (10,275.33 t·km−2) and Pattern C (1196.39 t·km−2) were larger than those from Pattern B (218.84 t·km−2) and Pattern D (693.84 t·km−2). These results indicated that greater attention should be paid to Pattern A and Pattern C because of the largest sediment delivery effect. Multiple stepwise regressions analysis suggested that the contribution of main runoff-related factors to event sediment yield varied with different flood patterns. In addition, hysteretic analysis between suspended sediment concentration and runoff suggested that counter-clockwise and figure-eight loops were the dominant loops. The results provided a useful information to flood pattern classifications and suspended sediment dynamics research, and enriched the sediment control theory at the watershed scale.