南水北调中线工程运行以来汉江中下游水文情势演变分析

Analysis on the Evolution of Hydrological Situation in the Hanjiang Mid-Lower Reaches River since the Application of the Middle-Route South-to-North Water Diversion Project

汉江中下游流域水文情势自南水北调中线工程运行以来发生了显著变化。为研究工程调水对汉江中下游的影响,选取黄家港等6个干流水文站长序列历史资料进行统计分析并基于GAMLSS模型进行趋势性检验,对引起工程前后水量变化的原因进行分析。结果表明:(1)工程运行后中下游水量较历史时期显著减少,受降水偏少影响水量减幅高于年均调水量,其中黄家港站水量减小幅度达31.8%;各水文站实测水位显著下降,皇庄站以下河段平均水位较调水前降幅在1 m以上;径流年内分配进一步均化,由于大量拦蓄夏汛、秋汛初期洪水,径流量月最大值出现时间延迟至10月。(2)经趋势检验分析,黄家港、襄阳、皇庄和仙桃站年径流、汛期径流序列均值呈显著下降趋势,但序列标准差尚无明显趋势变化。(3)工程运行以来天然降水减少、外调水量增加、沿江取用水量增大等是引起汉江中下游水文情势发生显著变化的重要因素。

The hydrological situation of Hanjiang Mid-lower Reaches River has changed significantly since the application of the Middle-Route South-to-North Water Diversion Project.This study aims to analyze the impact of the project on hydrological situation in Hanjiang Mid-lower Reaches,and reveal the reasons for the variation of water volume before and after the application of the project.To this end,long-term observed streamflow series from 6 hydrological stations of Hanjiang Mid-lower Reaches River were obtained,and subsequently statistical analysis and trend test analysis based on the GAMLSS model were applied.The results show that:(1)Since the application of the project,the water volume in the Hanjiang Mid-lower Reaches River has decreased significantly when compared with the period before the project,e.g.,the average runoff of Huangjiagang station has decreased by 31.8%.The observed water level series from 6 stations also show a clear downtrend,with the average water level of the reach below Huangzhuang station decreased by more than 1 m.The intra-annual variation of runoff has been further weakened due to retained summer flood and early autumn flood,with the occurrence time of maximum monthly runoff delayed to October.(2)Through trend test and analysis,the mean value of annual runoff series and flood season runoff series from Huangjiagang,Xiangyang,Huangzhuang and Xiantao stations show a significant downward trend,with their standard deviation values show no significant change.(3)The decrease of water volume in the Hanjiang Mid-lower Reaches River since the application of the project could be attributed to the reduction of precipitation,the increase of inter-basin water transfer and the increase of water intake and consumption along the river.