547 / 2024-07-16 20:41:31

Response of Channel Morphology in the Lower Yellow River to Water and Sediment Regulation of Xiaolangdi Reservoir

Lower Yellow River; water-sediment regulation; braided reach; morphological adjustments

Subtheme 7: Sediment Regulation and Management > Topic 5: Reservoir Sediments Management

To provide theoretical basis for the water-sediment regulation of Xiaolangdi Reservoir in the future, the riverbed evolution and morphological adjustments were comprehensively investigated based on the physical model on typical braided reach in Lower Yellow River (HGK-JHT Reach). Results revealed two key conclusions. (i) With the increase of testing discharge, both the mainstream width and depth increased continuously, and the increase rate in depth was obviously greater than that in width. Correspondingly, the geometric coefficient gradually decreased. This indicated that the adjustment trend of cross-sectional profile was from relatively wide and shallow to relatively narrow and deep, that is, Case 4000 m³/s exhibited rather stronger mainstream recovery capacity. (ii) Spatially, the adjustment patterns of mainstream geometry varied significantly among the studied cross-sections. For the reach upstream Section JLG, from Section JLG to Section CG, and downstream of Section CG, the adjustments of mainstream geometry were dominated by vertical deepening, lateral widening or combined deepening and widening, and vertical deepening, respectively. Besides, there also were some stable studied cross-sections in HGK-JHT Reach where the main channel dimensions fluctuated slightly. The spatial differences in adjustment patterns needed to be carefully considered when making relevant training measures. In this study, the morphological responses to different management strategies in typical braided reaches in Lower Yellow River were preliminary revealed. However, owing to the complexities of channel evolution, more efforts are necessary to develop the quantitative relationship between riverbed adjustment and related water-sediment conditions in order to serve the optimization of water-sediment regulation of Xiaolangdi Reservoir.