黑河流域参考蒸散量的时空变化特征及影响因素的定量分析

利用黑河流域及周边地区14个气象站的1960—2009年逐日气象资料,基于FAO推荐的 Penman-Monteith模型分析了黑河流域近50 a来潜在年、 季参考蒸散量ET₀的时空分布特征,同时利用敏感分析计算了流域内不同区域典型气象站ET₀对各气候要素的敏感系数,并结合各气候要素的多年相对变化定量探讨了导致ET₀变化的主导因素。结果表明:黑河流域年ET₀表现出明显的南北差异,亦即从南到北呈增大趋势,上游祁连山区年ET₀约568~700 mm,中游走廊平原约800~900 mm,下游的金塔、 鼎新一带约1 000 mm,额济纳地区则高达1 150 mm以上。各季节ET₀亦呈北多南少特征,且ET₀的年内分布以夏季最多,春季次之,秋冬最少。近50 a来,黑河流域年、 季平均ET₀整体呈减小趋势,但亦存在区域差异,其中上游ET₀略有增加,而中下游以减小趋势为主。就年平均敏感系数而言,上游的托勒站和中游的高台站皆对相对湿度敏感性最强,而下游的额济纳旗对平均风速最为敏感。不同站点各季节/月ET₀对气候要素的敏感性有所差异。风速是引起ET₀变化的主导因素,相对湿度和日照时数的贡献则较小。

Temporal and Spatial Variation Characteristics and Quantification of the Affect Factors for Reference Evapotranspiration in Heihe River Basin

Based on the daily data from 1960 to 2009 of 14 meteorological stations in Heihe River Basin and the surrounding areas,spatial and temporal distributions of the reference evapotranspiration in the Heihe River Basin were analyzed after calculation with the Penman-Monteith method recommended by FAO.Nondimensional relative sensitivity coefficients of reference evapotranspiration to climate elements of three representative stations in different regions were calculated to research the dominant factor of ET0’s change combined with the relative change of the climate element.The results showed that obvious regional difference of annual and seasonal ET0 in the Heihe River Basin and the former is estimated to be about 568-700 mm in the upper course,800-900 mm in the Hexi corridor plain and over 1000 mm in the lower course.The ET0 of summer is the most in a year,followed by spring,autumn and winter is the least.In general,the annual and seasonal ET0 all decreased in past the 50 years,but also with regional difference,which increased slightly in the upper course and decreased in middle and lower course.The relative humidity is the most sensitive variable to annual ET0 in Tuole and Gaotai which belong to the upper and middle course,however,wind speed is the most sensitive variable in Ejina which belongs to the lower course.The seasonal and monthly sensitivity of climate elements in the three sites have a little difference.Wind speed is the dominant factor causing change of ET0,however,the relative humidity and sunshine duration contributed little.