Department of Earth & Environmental Science, Xi'an Jiaotong University, Xi'an 71009, China.
Department of Earth & Environmental Science, Xi'an Jiaotong University, Xi'an 71009, China.
Sci Total Environ. 2020 Jan 1;698:134261. doi: 10.1016/j.scitotenv.2019.134261. Epub 2019 Sep 3.
Sediment in rivers is the dominant material source for ecosystems in lower reaches and estuaries, and it is undergoing large variations globally in recent decades. Though we have knowledge that human activities are greatly affecting land surface ecosystem processes and functions, the relationships between sediment transport regime and the intensifying human activities, are still poorly understood. This study was to investigate the changes of sediment transport regime due to the large-scale ecological restoration in the Middle Yellow River Basin (MYRB). In this study, we examined the change of the sediment rating curves using daily sediment load and streamflow data from 30 stations during time periods including pre- and post-ecological restoration in this region. We found the pair-relationship of the rating parameters (coefficient and exponent), denoted as coefficient-exponent pair-line, is a critical indicator that can detect the shift of sediment transport regime due to disturbed land surface conditions, though the changed hydrometeorological condition may just influence the absolute values of the rating parameters. Our analysis indicates there was a significant and interesting change of the sediment transport regime in the MYRB characterized by the consistent shift of the coefficient-exponent pair-line, together with an increasing exponent and a decreasing coefficient. This changed sediment transport regime can tell that sediment delivery would become lower for normal discharge conditions but potentially higher for extreme discharge conditions, and this phenomenon seems more distinct in relatively smaller watersheds, suggesting a higher risk of the potential high sediment delivery for extreme rainfall conditions especially for small watersheds. Our study would be informative and valuable to decision makers for sustainable watershed management in the MYRB when considering the changed sediment delivery.
河流泥沙是下游和河口生态系统的主要物质来源，近几十年来，全球范围内泥沙的变化幅度很大。虽然我们知道人类活动极大地影响了陆地表面生态系统的过程和功能，但泥沙输移机制与日益加剧的人类活动之间的关系仍未得到很好的理解。本研究旨在探讨由于黄河中游流域（MYRB）大规模生态恢复而导致的泥沙输移机制的变化。在这项研究中，我们使用该地区生态恢复前后时段的 30 个站点的日泥沙负荷和流量数据，检查了泥沙等级曲线的变化。我们发现，等级参数（系数和指数）的对关系，即系数-指数对线条，是一个关键指标，可以检测到由于陆地表面条件干扰而导致的泥沙输移机制的转变，尽管变化的水文气象条件可能只是影响等级参数的绝对值。我们的分析表明，黄河中游流域的泥沙输移机制发生了显著而有趣的变化，其特征是系数-指数对线条的一致移动，以及指数的增加和系数的减小。这种变化的泥沙输移机制表明，在正常流量条件下，泥沙输送量可能会降低，但在极端流量条件下，泥沙输送量可能会升高，这种现象在相对较小的流域更为明显，表明在极端降雨条件下，特别是在小流域，潜在的高泥沙输送风险更高。当考虑到泥沙输送的变化时，本研究将为决策者在黄河中游流域进行可持续的流域管理提供有价值的信息。
