黄河北干流水沙时空变化特征及协调性分析

为了解黄河北干流河段径流和输沙的时空变化规律及趋势,基于2002—2021年黄河北干流水沙数据,采用Mann-Kendall检验、突变点检验、小波分析、水沙关系协调性分析等方法,对黄河北干流河段的头道拐、龙门、潼关3个水文站2002—2021年的水沙时空变化特征进行了分析。结果表明:黄河北干流河段的输沙年内不均匀程度和集中度均大于径流,并且年内特征变化更加显著;各站径流集中期主要出现在9月,而输沙集中期主要在8月和9月;流域内水沙变化的显著突变年份多发生在2005年和2017年,可能与近年大型水利工程的调控影响相关;3个水文站水沙序列主要时间尺度对应的周期分别为13、10、9 a;黄河北干流的水沙不协调性在2008年之前主要表现为水少沙多,而在2008年之后则表现为水多沙少,其中头道拐的来沙系数始终小于0.009,一直处于水多沙少的状态。总体上,研究期内黄河北干流河段径流量在不断上升,而输沙量明显减少,且随着时间的推移水多沙少的趋势愈发显著。

Analysis of spatial and temporal variation characteristics and coordination of water-sediment in the north main reach of Yellow River

In order to investigate the temporal and spatial variations patterns and trends of runoff and sediment in the northern main reach of Yellow River, by adopting various methods including Mann-Kendall test, abrupt change analysis, wavelet analysis, and coordination analysis of water-sediment relationship, this study analyzed the variations of water and sediment for the hydrological stations of Toudaoguai, Longmen and Tongguan, based on the water and sediment data along the northern reach of Yellow River from 2002 to 2021. The findings revealed that the unevenness and concentration of sediment were greater than those of runoff, and the intra-annual characteristic variations exhibited more significant. Concentrated period for runoff was primarily in September, while sediment was mainly concentrated in August and September. Significant abrupt changes in water-sediment characteristics occurred in 2005 and 2017, which may be related to the regulatory impact of large-scale water conservancy projects in recent years. The dominant periodicities for water-sediment sequences were found to be 13 years, 10 years, and 9 years for Toudaoguai, Longmen, and Tongguan stations, respectively. Before 2008, the water-sediment relationship indicated sediment dominance over water, while after 2008, the trend shifted to water dominance. Particularly, sediment yield coefficient at Toudaoguai remained consistently below 0.009, indicating the persistent water dominance. Overall, the trend showed a continuous increase in runoff while sediment witnessed a noticeable decrease, showing an increasingly significant trend towards runoff dominance over sediment.