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利用1951～2008年黄河与长江流域逐月降水和径流资料,对流域年径流变化进行趋势性检验,分析年降水量和径流量的相关关系变化,比较不同时段流域降水和径流的变化趋势和双累积曲线,以及径流对降水的敏感性变化.结果表明,黄河干流上游年降水量微弱下降,中下游降水减少趋势显著,为8.8～9.8mm/10a;而全流域径流量均呈现显著递减的趋势,为7.8～10.8mm/10a(通过95%置值度检验);径流系数也明显下降,下降范围为0.013～0.019/10a,流域产流能力下降,径流减少趋势在20世纪80年代末至90年代初发生突变.长江流域大部降水减少趋势显著,为18.2～24.7mm/10a;上游(寸滩站,宜昌站)径流减少趋势显著,为9.9～7.2mm/10a,中游(汉口站)和下游(大通站)径流呈微弱下降趋势,为2.9～2.1mm/10a;长江流域上游径流系数增加不显著,中下游径流系数呈显著增加趋势,速率分别0.005/10a和0.005/10a,表明中下游产流能力增强.根据水文参数公式计算,与1951～1969年相比,1970～2008年,降水减少和人类活动引起的下垫面变化对黄河流域径流减少量的贡献率分别为11%和83%;在长江流域,降水减少对径流量变化的贡献占29%,人类活动引起的径流量增加占71%.1980～2008年,黄河流域由于下垫面变化造成径流量减少的比例在兰州、三门峡、花园口、利津分别为97%,83%,83%和91%,降水引起的径流量减少比例分别为3%,17%,17%和9%.长江流域降水减少对寸滩、宜昌、汉口、大通径流量减少的贡献分别为89%,74%,43%和35%,下垫面变化对径流增量的贡献分别为11%,26%,57%和65%.人类活动的作用强度逐年增大,2000年之后,下垫面变化对黄河、长江流域径流变化量的贡献率上升到84%和73%.下垫面变化引起了黄河下游径流减少和长江下游径流增加,在干旱区和湿润区对径流变化的作用相反.造成这一现象的原因是:黄河流域人类的活动用水量的增加直接造成径流减少;长江流域因太阳辐射下降引起实际蒸发量下降,同时湖泊面积减少,下垫面硬化也在一定程度上造成产流能力增加.
Using the monthly precipitation and runoff data of the Yellow River and the Yangtze River basin from 1951 to 2008, the trend of annual runoff change in the basin was tested, the correlation between annual precipitation and runoff was analyzed, and the trend of precipitation and runoff in different periods was compared with that of double Cumulative curves and the sensitivity of runoff to precipitation.The results show that the annual precipitation in the upper reaches of the Yellow River decreases slightly while the precipitation in the middle and lower reaches has a decreasing trend of 8.8 ~ 9.8mm / 10a, while the runoff in the whole basin shows a significant decreasing trend (From 95% to 95%). The runoff coefficient also decreased significantly, with a decreasing range of 0.013-0.019 / 10a. The runoff abatement decreased with the trend of decrease in runoff from the late 1980s to the 1990s There was a sudden change at the beginning of the year, and the precipitation in most of the Yangtze River decreased significantly from 18.2 to 24.7 mm / 10a. The runoff in the upstream (Cuntan Station and Yichang Station) was significantly decreased from 9.9 to 7.2 mm / 10a in the middle reaches (Hankou Station) and The runoff in the downstream (Datong Station) showed a weak downward trend, ranging from 2.9 to 2.1 mm / 10a. The runoff coefficient in the upper reaches of the Yangtze River increased only insignificantly and the runoff coefficients in the middle and lower reaches increased significantly at the rates of 0.005 / 10a and 0.005 / 10a, respectively, Production According to the formula of hydrological parameters, compared with 1951-1969, the contribution of the change of underlying surface due to the decrease of precipitation and human activities to the decrease of runoff in the Yellow River Basin from 1970 to 2008 was 11% and 83%, respectively In the Yangtze River Basin, the decrease of precipitation contributed 29% to the change of runoff and the increase of runoff caused by human activities accounted for 71%. From 1980 to 2008, the proportion of runoff in the Yellow River basin due to the change of underlying surface was decreased in Lanzhou and Sanmenxia , Huayuankou and Lijin were 97%, 83%, 83% and 91% respectively, and the proportion of runoff reduction caused by precipitation was 3%, 17%, 17% and 9% The contributions of Hankou and Chase populations to runoff reduction were 89%, 74%, 43% and 35%, respectively, and the contribution of underlying surface changes to runoff increment was 11%, 26%, 57% and 65% respectively. After 2000, the contribution of the underlying surface changes to the runoff in the Yellow River and the Yangtze River increased to 84% and 73%, respectively, and the change of underlying surface caused the decrease of runoff in the lower Yellow River and the increase of runoff in the lower reaches of the Yellow River. The effects of regional and humid zones on runoff changes are reversed. The reason for this is that the Yellow River Increased consumption of water as a direct result of human activities reduce runoff; the Yangtze River due to decreased solar radiation cause actual evapotranspiration decline, while reducing the lake area, resulting in increased runoff capacity of the underlying surface hardening to a certain extent.