基于生态补水的永定河流域径流变化分析

Streamflow changes of Yongding River basin after ecological water compensation

大规模的跨区域生态水量调度,在恢复长期断流河道生态水量需求的同时,也打破了流域原有的水文循环规律.为识别生态补水对河道径流的影响,本文开展了永定河流域年径流历史序列时空变化及生态补水前后对比分析.结果表明:流域年径流量呈显著性减少趋势,且在1983年存在变点;变点年后年径流量大幅度减少,且日径流量历时曲线显示变异后低流量的分布历时增加,年内日径流量的差异变大;开展大规模生态补水工作以后,官厅水库年入库流量较之前多年平均有明显提高,年内逐月流量过程恢复明显的双峰过程,生态流量满足率显著提高,生态补水对现状条件下河道径流起到了积极作用.

To assess impact of ecological water replenishment on streamflow in the Yongding River basin,temporal and spatial changes of streamflow from 1961-2018 and changes before and after ecological water compensation were analyzed.Annual streamflow has shown a significant decreasing trend with change point of 1983.After the change point year,the average annual streamflow decreased significantly,the daily stream flow duration curve showed that the distribution duration of low streamflow increased,the difference of daily runoff of the year became larger.After large-scale ecological water replenishment,annual inflow of Guanting Reservoir has significantly increased compared with average years before,monthly flow process has an obvious bimodal process,satisfaction rate of ecological flow has significantly increased.Ecological water replenishment has played a positive role in streamflow under current conditions.