基于SWAT模型的旬河流域气候变化水文响应研究

Simulation of the Hydrological Response of Xunhe River Basin to Climate Change Using the SWAT Model

径流量是体现流域水量特征的重要指标。旬河作为汉江上游的主要支流,其径流量变化直接关系到丹江口水库(南水北调中线工程水源地)的储水量。以历史时期(1995-2015年)旬河流域实测径流量数据为基础,选择驱动SWAT水文模型,定量探究旬河流域径流量对气候变化的响应。结果表明,校准期和验证期决定系数(R~2)分别为0.85和0.87,Nash-Sutteliffe效率系数(NSE)分别为0.85和0.84,SWAT水文模型对旬河流域径流量模拟结果良好。采用英国Hadley气候中心预测的未来气候模式RCP2.6、RCP4.5、RCP6.0、RCP8.5,对2036-2055年的气象数据进行4种未来气候情景模拟,发现在历史气候情景下,三季度降水量对全年径流量贡献度最大,且四季度的径流量对三季度的降水量存在一定滞后效应;在RCP8.5情景下,雨季将提前且持续周期延长。研究结果可为政策部门在水资源宏观调控、极端气候预防和防洪减灾等方面提供参考。

Runoff is important for characterizing the water resources of a watershed and the climatic factors primarily affecting runoff are precipitation and temperature.The frequency of extreme climate events such as extreme precipitation and extreme drought has been increasing in some parts of China,seriously threatening economic development and the security of local residents.Xunhe River is one of the main tributaries of the upper Hanjiang River and variation of runoff from the basin has important impacts on water input to Danjiangkou Reservoir,consequently affecting source water in the middle route of the South-to-North Water Diversion Project.It is therefore necessary to conduct a systematic,quantitative study of the response of basin runoff to anticipated climate change scenarios.To begin,a SWAT hydrologic model was constructed to simulate runoff in Xunhe River basin,based on monthly runoff data(1995-2015)recorded at the Xiangjiaping Hydrological Station.Data from 1998-2008 was used for calibration and data from 2009-2015 was used for validation.The correlation coefficient(R^(2))was 0.85 for the calibration period and 0.87 for the validation period,and the respective Nash-Sutcliffe efficiency coefficients(NSE),indicating the reliability of the SWAT model,were 0.85 and 0.84.Runoff was then simulated in the Xunhe River basin for the period 2036-2055 using four climate scenarios predicted by the UK Hadley Climate Center(RCP2.6,RCP4.5,RCP6.0 and RCP8.5).Under the RCP climate scenarios,precipitation and temperature are both higher than historically and runoff presented an increasing trend.Precipitation during the third quarter contributed most to the annual runoff,while runoff in the fourth season decreased.Under climate scenario RCP8.5,the rainy season comes earlier and lasts longer.The simulation results for these scenarios can be referenced by policymakers for regulating water resources,mitigating extreme climatic events,flood control and disaster reduction.