洞庭湖三口河系地区径流演变情势与农业用水面临的挑战

The Evolutionary Trend of the Runoff and the Water Challenge Faced by Agriculture in the Three Outlets Area of Dongting Lake

基于1960-2012年实测径流及降水资料,利用M-K检验分析法得出三口河系年径流变化趋势及汛期径流变化趋势都显著减少,年径流量与年降水量变化过程中的突变年份为1973年与1982年;以1960-1968年为基准期,运用累积量斜率变化率比较方法,计算得到流域降水量变化和水利工程运行对洞庭湖三口径流量减小的影响贡献率在1974-1982年间分别为15.25%和84.75%,在1983-2012年间依次为11.01%及88.99%;随着本区农业生产规模的不断扩大,工程性缺水与季节性缺水问题日益凸现,到2020年洞庭湖三口河系地区90%保证率总缺水量为44 127万m3,其中农业生产缺水39 652万m3,农业供需水量的缺口对该区农业可持续发展将产生不同程度的约束性。

The results are obtained based on the field-survey runoff and rainfall data. By the M-K test method, the change trends of the annual runoff and the runoff in the flood season of the three outlets river system decreases significantly and the abrupt change years in the change process of the annual runoff and the annual precipitation are 1973 and 1982. The contribution rates of the precipitation change and the hy- draulic engineering operation to the runoff decrease of three outlets are calculated by the comparative method of the slope changing ratio of cumulative quantity taking 1960-1968 as the benchmark. These rates are respectively 15.25% and 84.75% in 1974-1982, and are 11.01% and 88.99% in 1983-2012. The engineering water shortage and the season water shortage are more obvious with the development of agriculture. The volume of the total water shortage in the three outlets area with the 90% assurance rate is 44 127× 10 4 m3. The volume of the agricultural production water shortage is 39 652× 10 4 ms , which constraints the sustainable development of agriculture.