Effect of soil and water conservation measures on regime-based suspended sediment load during floods

Abstract

Understanding the changes in runoff-sediment relationships is a great help for implementing soil and water conservation measures, particularly in regions with severe erosion. We selected a typical coarse sandy catchment on the Loess Plateau to investigate the changes of the runoff-sediment relationships with a data set of 62 years. A change point occurred in 1979, dividing the runoff and sediment load series into a baseline period (1954–1979) and a changing period (1980–2015). A total of 342 flood events were classified into three regimes using hierarchical clustering method. Regime A (162 events) was characterized by the shortest duration, lowest flood crest, and the least flow depth. Regime B (165 events) was characterized by a medium runoff depth, medium flow variability, and medium duration. Regime C merely include fifteen events with longest flood duration, the highest runoff depth, and the largest peak discharge. The sediment yield of flood regime A, B, and C accounted 14.2 % (1.09 × 108 t), 51.8 % (3.99 × 108 t), and 34.0 % (2.62 × 108 t) of the total sediment yield, respectively. The Support vector machines method was applied to established models to predict event sediment yield. It is demonstrated that the performance of models are good for different flood regimes.