1961─2010年降水和土地利用变化对淮河干流上中游径流的影响

Impacts of Precipitation and Land Use Change on the Main Stream of Huai River from 1961 to 2010

为了研究近50a来降水和土地利用变化对淮河干流上中游径流变化的影响程度,利用逐日径流和降水资料,采用线性趋势、累积距平、Mann-Kendall非参数检验法和t检验等统计方法,探讨了淮河干流上中游径流的变化趋势、突变等,并基于双累积曲线,构建了降水-径流关系模型,定量估算了降水和土地利用变化对径流的贡献程度。结果表明,(1)淮河干流上游径流量呈增加趋势,其线性倾向率为0.08×10~8 m^3·a^(-1),而中游呈减少趋势,其线性倾向率为-0.38×10~8 m^3·a^(-1),且中游径流量C_v大于上游;上游和中游降水量均呈增加趋势,其线性倾向率分别为0.34和1.72 mm·a^(-1);径流量的年际波动均大于降水量。(2)上游径流量突变年份为1972年,降水对径流量影响的基准时段为1961-1972年;中游径流量突变年份为1985年,降水对径流量影响的基准时段为1961-1985年。(3)相对于基准时段,降水有利于径流增加,而土地利用变化导致径流减少。(4)土地利用变化是引起径流变化的主导因素,对上游和中游径流量变化的贡献率分别为76%和74%;降水对径流量变化起着次要作用,但其影响也不容忽视。

In order to evaluate the impacts of precipitation and land-use change on the streamflow in the upper and middle reaches of Huai River from 1961 to 2010, this study analyzed the tendency and mutation of streamflow by adopting historical daily streamflow and precipitation data together with statistical methods, such as linear regression, accumulative anomaly analysis, Mann-Kendall non-parametric test, and t-test. Based on the double mass curves principle, we established the model of annual streamflow-precipitation to quantitatively estimate the contribution of change at precipitation and land-use on streamflow. The results showed that annual streamflow increased at a linear trend rate of 0.08×108 m3·a-1 in the upper reaches of Huai River, while decreased in the middle reaches at a linear trend rate of-0.38×108 m3·a-1, and coefficient of variation of annual streamflow in the middle reaches was greater than the upper reaches. Meanwhile, precipitation in both reaches increased at linear trend rate of 0.34 and 1.72 mm·a-1, respectively. However, the inter-annual fluctuation of streamflow was more notable than precipitation. In addition, the abrupt change of streamflow occurred in 1972. The period of 1961─1972 was then determined as reference period in the upper reaches. The abrupt change and reference period of the middle reaches were 1985 and 1961─1985, respectively. Furthermore, compared to the reference period, precipitation would increase streamflow, but land use change tended to incur a decrease of streamflow in both reaches. Land use change was the main driving force for the change of annual runoff compared with precipitation change, with contributions being 76% and 74%for the upper and the middle, respectively. However, it is worth to note that the contribution of precipitation to the change of streamflow could not be neglected.