Evolution patterns and spatial sources of water and sediment discharge over the last 70 years in the Yellow River, China: A case study in the Ningxia Reach

Abstract

The hydrology and sediment processes in large rivers play important roles in maintaining aquatic and coastal ecosystems and advancing civilization and production in human systems. Therefore, quantitatively analyzing the spatiotemporal variability and dynamics of water and sediment discharge in large rivers is essential for improving watershed management and sustainable development in the areas surrounding rivers, especially the Yellow River, which is one of the most sediment-laden rivers in the world. In this study, we analyzed the evolution patterns and spatial sources of water and sediment discharge in the Yellow River from 1951 to 2020 and determined the impacts of different factors on water and sediment discharge variations. The results showed that the annual water and sediment discharge significantly decreased (p < 0.05) over the past 70 years, with an abrupt change occurring in 1986. The first dominant periodicity of water discharge was approximately 29 years, while the first dominant periodicity of sediment discharge was approximately 28 years. In terms of the water and sediment discharge sources, the dominant factor affecting variations in water discharge was water diversion from 1951 to 2020, while the dominant factor affecting variations in sediment discharge was sediment aggradation from 1951 to 1985 and changed to tributary inflow sediment from 1986 to 2020. In addition, the water and sediment discharge changes were also affected by anthropogenic activities, such as water and sediment diversions, dams and reservoirs, and water and soil conservation measures. In particular, the water and sediment interception capabilities of the established soil and water conservation measures gradually became saturated over time. Specifically, the maximum water and sediment interception capabilities of the current soil and water conservation measures were 12.2 billion m³ and 1.9 Gt, respectively. Overall, the results of the present study can help tailor water and sediment regulation countermeasures in the future.

Keywords: Anthropogenic effects; Hydrology and sediment; Large rivers; Spatiotemporal change.