1965—2018年广西西江流域参考作物蒸散量时空演变及其影响因子

估算参考作物蒸散量(ET₀)有助于揭示流域的水热平衡和水循环过程,为合理利用与开发流域水资源提供基础。本研究通过重新拟合研究区的净短波辐射系数,使用改进后的Penman-Monteith模型,计算1965—2018年广西西江流域的ET₀,使用Mann-Kendall法对ET₀进行趋势分析与突变点检测,用反距离权重法插值后分析ET₀时空演变特征,根据气候因子的贡献率判断ET₀的影响因子。结果表明:在空间上,ET₀呈现随海拔降低而增加的趋势,其高值主要位于流域中部地区,而低值位于西北侧的云贵高原边缘及斜坡带,春季ET₀呈现出经度梯度性,夏季ET₀与年际的空间格局类似;在时间上,流域年均ET₀为637.2mm,增长率为-0.018 mm·a^-1,整体呈微弱的下降趋势。除春季(0.053 mm·a^-1)呈上升趋势外,夏季(-0.053 mm·a^-...

Spatial and temporal variations of reference evapotranspiration and its influencing factors in Guangxi Xijiang River Basin from 1965 to 2018

Estimation of reference evapotranspiration(ET0)could contribute to revealing waterheat balance and water cycle process and consequently provide reference for the sustainable utilization and exploration of regional water resources.Here,we re-fitted the net shortwave emissivity and calculated ET0 in Guangxi Xijiang River Basin from 1965 to 2018,using improved PenmanMonteith model.The trend analysis and mutation point detection of ET0 were performed by MannKendall method.The spatial-temporal variations of ET0 were analyzed by interpolation with inverse distance weighting method.Factors influencing ET0 were determined based on the contribution rate of meteorological factors.At spatial scale,ET0 presented an increasing tendency with decreasing altitude.The highest ET0 values were mainly distributed in the central part of the basin,while the lowest values occurred in the edge and slope zone of the Yunnan-Guizhou Plateau,which lies in the northwest part of the basin.ET0 in spring varied with the longitude,while summer ET0 showed a similar spatial pattern to that of the inter-annual ET0.The mean annual ET0 of the basin was 637.2 mm,with a declining rate of-0.018 mm·a^-1.The ET0 in spring,summer,winter and autumn were 0.053,-0.053,-0.007 and-0.011 mm·a^-1,respectively.ET0 in all the seasons except spring showed an downward trend.The largest increase in ET0 occurred in winter.The importance of dominant factors influencing ET0 of the basin followed an order of relative humidity(with a contribution rate of 39.0%)>average wind speed(27.2%)>sunshine duration>average temperature.Relative humidity negatively affected ET0,with a correlation coefficient of-0.673.Sunshine duration,average wind speed,and average temperature positively affected ET0.The dominant driving factors of ET0 and their contribution rates varied across different parts of the basin.