Changes in runoff and sediment load of the Huangfuchuan River following a water and soil conservation project

In this study, we analyzed changes in the water and sediment properties in the Yellow River during the flood season, which is the period with the largest runoff yield and sediment load in this river.The aim of this study was to understand the impact of water and soil conservation measures during this crucial season, and we focused on the Huangfuchuan drainage basin as the study region. We analyzed factors including the precipitation, runoff and sediment yield, and suspended sediment grain-size distribution during each of the flood seasons in 1986 to 1990 (P1) and 2006 to 2010 (P2).The results showed that most of the precipitation during the flood season was concentrated in the southeastern part of the basin.The mean flood season precipitation was similar in the two periods, with 260.1 mm and 256.9 nun in P1 and P2, respectively, but the frequency of floods in the basin decreased by 59.4% during P2. Compared with P1, the mean flood volume, sediment load, and duration during P2 decreased by 52.17%, 68.57%, and 1.52%, respectively.The composition of the sediments in the Huangfuchuan drainage basin was dominated by the presence of silts, which represented 61.2% and 96.6% of the total sediments in P1 and P2, respectively. The results obtained in this study demonstrate that the water and sediment conditions in the Huangfuchuan drainage basin during the flood season have improved over time, with a more homogeneous suspended sediment composition, more concentrated water and sediment processes, and decreases in the flood frequency, volume, and sediment transport. Our results indicate the effectiveness of river basin regulation, and they may be used as a reference for treatment of the main sediment production areas in the Yellow River.