Changes in Runoff and Sediment Loads in the Tuhai River Basin and the Factors Influencing These Changes

Abstract

In this study, rainfall, runoff, and sediment load data were collected from the Tuhai River Basin from 1972 to 2021. The Mann–Kendall test, runoff–sediment curve, and double mass curve were used to identify the characteristics and factors influencing runoff and sediment loads in the Tuhai River Basin. The results showed that the average annual runoff and sediment loads in the river basin were 4.03 × 108 m3 and 3.52 × 108 kg, respectively; furthermore, the flood season (June–September) accounted for 79.9% and 99.4% of these values, respectively. There were no apparent runoff trends in the annual, flood, and non-flood (October–May) stages, and the annual and flood season sediment loads decreased significantly. The abrupt change points of annual and flood season runoff in the Tuhai River Basin mainly occurred from 2003 to 2004 and from 2013 to 2014. Moreover, the abrupt change points of annual and flood season sediment load only occurred from 1978 to 1979. The runoff–sediment curve showed a clear power function relationship between runoff and sediment loads. The runoff in the Tuhai River Basin from 2003 to 2013 was mainly affected by precipitation. Additionally, the contributions of human activities to runoff and sediment load reduction in the Tuhai River Basin were 57.7–88.9% and 63.1–86.0%, respectively. The increase in human water consumption was the main reason for the decrease in runoff in the Tuhai River Basin. Furthermore, the measures taken in soil and water conservation and reservoir construction were the main factors behind a reduction in sediment loads in the Tuhai River Basin.