Effects of cascade reservoir systems on the longitudinal distribution of sediment characteristics: a case study of the Heihe River Basin

Abstract

Spatial variations in grain size parameters can reflect river sediment transport patterns and depositional dynamics. Therefore, 22 surficial sediment samples taken from the Heihe River and its cascade reservoirs were analyzed to better understand the impact of cascade reservoir construction on sediment transport patterns in inland rivers in China. The results showed that the longitudinal distribution of sediment grain size in the Heihe River was significantly affected by the influence of the cascade reservoirs. The retention rate in the cascade reservoir of the Heihe River reached 79% (193.53 Mt/year), which caused most of the fine sand to accumulate in the reservoir, and the sediment fining degree reached approximately 50%. However, the water discharged from the dam caused serious erosion of the riverbed and coarsening of the sediment, and the coarsening degree was approximately 500%. The backwater zone of the reservoir was influenced by both backwater and released water, and the coarsening degree of sediment was approximately 101%. Sedimentary environmental analysis revealed that the characteristics of the sediment grain size in an upstream tributary of the Heihe River were more influenced by source material than by hydrodynamic conditions, while the grain size characteristics of the mainstream sediments were controlled mainly by hydrodynamic conditions. The characteristics of sediment transport in different reaches of the Heihe River were studied, and the results may provide references for the operation of cascade reservoirs and the sediment control of reservoirs.

Evaluation of land resilience against natural disasters using ecosystem services approach in Kendari City, Southeast Sulawesi, Indonesia

“…Figure 4 shows that inundation occurs in residential areas due to prolonged rains, while the rivers cannot accommodate the overflowing water (Riyanto, Rizkinia, Arief, & Sudiana, 2022;Shige-Eda, Akiyama, Duran, Kanaya, & Katsura, 2022). The puddle's dark brown color indicates that the upstream area's erosion process is intensive, so various forms of prevention, such as reforestation or the construction and checking dams, need to be carried out as soon as possible (Dunn & Minderhoud, 2022;Singh et al, 2022;Y. Wang et al, 2022).…”

Spatial Variation and Terrain Gradient Effect of Ecosystem Services in Heihe River Basin over the Past 20 Years

“…Climatic characteristics of the basin are a typical continental arid climate, little but concentrated precipitation, ample sunshine, and greater diurnal temperature range. With an average altitude over 1200 m, the topography varies significantly from south to north [51]. The regional climate is significantly different in the basin.…”