长江下游秦淮河流域径流变化及影响因素分析

Analysis on Variation and Influencing Factors of Runoff in Qinhuaihe River Basin in the Lower Reaches of the Yangtze River

为定量分析气候变化和人类活动对流域径流变化的影响,以我国经济高度发展的长江下游秦淮河流域为例,应用累积距平、线性趋势分析等方法,分析了其1987—2015年的水文气象变化趋势;基于水热耦合平衡方程,计算了流域年径流变化的气候弹性系数和下垫面弹性系数,对径流变化进行了定量的归因分析。结果显示:(1) 1987—2015年流域年径流呈增加趋势,并在2001年左右发生明显转变,由此将研究期划分为1987—2000年与2001—2015年两个阶段。(2)年降水量多年变化趋势并不明显,年潜在蒸散发总体呈上升趋势。与转变发生前相比,2001—2015年期间年均降水量增加2.42%,年均潜在蒸散发量增加6.24%,二者变化幅度不大,而下垫面参数变化幅度较大。(3)径流对于降水、潜在蒸散发以及下垫面的弹性系数分别为0.69,-0.92,-0.64,气候与下垫面变化对径流增加的贡献率分别为-9.6%,115.5%,可见人类活动对径流影响更大,同时也存在其他因素对径流变化产生较小影响。

The Qinhuaihe River Basin is located in the lower reaches of the Yangtze River which is highly developed area in China.In order to quantitatively evaluate the impacts of climate change and human activities on runoff and their contribution rates to runoff,the hydrological and meteorological trends in the Qinhuaihe River Basin from 1987 to 2015 were analyzed by employing the accumulative anomaly and linear trend analysis method.The coupled energy-water balance equation based on the Budyko hypothesis was employed to estimate climate elasticity and landscape elasticity of runoff,which were then used for attribution analysis of runoff change in Qinhuaihe River Basin.The main results were showed as follows:(1)An increasing trend of annual runoff was revealed during the period 1987—2015 in Qinhuaihe River Basin.An abrupt change was identified around the year 2001,the entire period was divided into two parts.(2)The trend of annual precipitation was not obvious,but the annual potential evapotranspiration showed the increasing trend.Compared with the period before the abrupt change,the annual average precipitation increased by 2.42%,the potential evapotranspiration increased by 6.24%,and the landscape parameter decreased by 49.77%during the period 2001—2015.(3)The runoff elasticity to the precipitation,potential evapotranspiration and landscape were 0.69,-0.92 and-0.64,respectively.The contribution rates of the climate change and landscape change were-9.6%and 115.5%,respectively,and the human activities was the main factor that led to the runoff increase.There were other factors that led to the runoff change in Qinhuaihe River Basin.