基于IHA-RVA法的生态治理对径流演变情势的影响评估

Assessment on Impact of Ecological Management on Runoff Evolution Based on IHA-RVA Method

研究流域径流演变情势及其对生态治理的响应,可为流域水资源合理利用和水生态治理提供重要指导。该文依据北洛河上游1964—2014年逐日平均流量和年降水量资料,采用双累积曲线法、双滑动平均法(MASH)和Mann-Kendall趋势检验法对径流过程变化进行了分析研究,采用水文指标变化范围法(IHA-RVA)对5组30个径流指标及其改变度进行了评估,对径流演变成因做了初步分析。结果表明:研究期内年径流呈现减少趋势,且以1979年和2002年为界可划分为基准期、水土保持治理期和生态恢复影响期;汛期流量下降较非汛期明显,减少幅度为35.6%;生态治理影响下径流指标整体水文改变度为74.35%,属于高度改变;5组30个径流指标中发生高度改变的指标占比增加,其中年极端流量组变化度最大,为94.77%。人类活动使得流域河川径流显著减少且波动性减弱,而水土保持、退耕还林(草)措施是核心驱动力。

The evolution of runoff and its response to ecological management can provide paramount guidance for the reasonable use of water resources and the management of water ecological at basin scale. With the help of daily average streamflow and yearly precipitation data from 1964 to 2014 in the upper reaches of Beiluo River, we analyzed and investigated the processes of streamflow changes using the methods of double cumulative curve, double moving average(MASH), and Mann-Kendall trend test. Moreover, the 30 streamflow indicators of 5 groups and their change degrees were evaluated utilizing the range of hydrological indicators change method(IHA-RVA), and a preliminary analysis was done for the causal of streamflow evolution. The annual streamflow showed the decreasing trend during the study period. Taken the years of 1979 and 2002 as the time nodes, the study period could be divided into the baseline period, the conservation management of soil and water period, and the impact of ecological restoration period. Compared with the non-flood season, the streamflow decreased by 35.6% in the flood season. Under the influence of ecological management, the overall change degree of hydrology caused by the streamflow index was 74.35%. Among the 30 streamflow indexes in the 5 groups, the proportion of index with the pronounced changes increased. The mostly changed degree was the group of annual extreme streamflow that the proportion accounted for 94.77%. Significantly reduced streamflow and its fluctuation could be resulted from the human activities, in which the key drivers were the conservation of water and soil and returning farmland to forest or grassland.