渭河流域河川径流对气候变化的时空响应机理

Spatiotemporal Response Mechanism of Runoff to Climate Change in the Wei River Basin

基于流域DEM、土地利用、土壤等空间数据,以及降雨、气温等气象数据,构建了渭河流域SWAT模型分区径流模拟平台,分析了历史气候变化对流域径流的时空影响;通过气候情景假设法,进一步研究了该流域河川径流对未来气候变化特征的时空响应.结果表明：在时间上,1990s气候变化对径流的减少程度大于2000s,减少贡献率分别约为75%和50%;年降雨增加/减少5%,年径流增加/减少10%~15%,年气温增加/减少0.5℃/1℃,年径流减少/增加幅度小于3%;季降雨增加5%或减少5%/10%,各季径流响应程度差异不大,但当季降雨增加到10%时,冬季径流增加显著（约50%）;春季和冬季径流对气温降低较敏感,秋季和冬季径流对气温升高较敏感,季气温增加或减少0.5℃/1℃,季径流变幅均小于10%.在空间上,历史气候变化对径流的影响程度为：上游大于下游,泾河大于北洛河;年径流对降雨的响应空间差异不大,但对气温上升的敏感度干流大于支流,对气温降低的敏感度干流小于支流;季径流对气候变化的空间响应均为干流大于支流.

Using the spatial data（ DEM,land use and soil darta） and Meteorological data（ precipitation and temperature data）,the Soil and Water Assessment Tool（ SWAT） model was applied to the Wei River Basin（ WRB）. Based on the（ SWAT） model,the spatiotemporal response mechanisms of runoff to climate change were assessed in the WRB. Results show that：（ 1） the SWAT model has suitable application in the WRB with R^2〉 0. 6,Ens 〉 0. 5 and Re 〈20%;（ 2） both the climate change in the 1990 s and 2000 s have adverse impacts on runoff,and the runoff decrement degrees are gradually weakened from the 1990 s（ 75%） to 2000 s（ 50%）and from upstream to downstream;（ 3） the annual runoff is negatively/positive correlated with the annual temperature/precipitation; no matter the annual temperature decrease or increase0. 5℃/1℃,the runoff change percentages are less than 3%; a 5% increase or decrease of annual precipitation would lead to a 10% ~ 15% increase or decrease of runoff respectively;（ 4） the runoff in spring and winter are more sensitive to the decrease of temperature,while the runoff in autumn and winter are more sensitive to the increase of temperature; the seasonal precipitation has positive impact on the seasonal runoff and the impact degree in of mainstream is greater than that in the tributary.