云南水分盈亏量变化特征研究

A Study on Changing Characteristics of Water Budget in Yunnan Province

为了揭示云南气象干旱的时空演变特征,基于Penman-Monteith方法计算云南各地1961年以来不同时段的潜在蒸散量,用降水量与潜在蒸散的差值即水分盈亏量作为气象干旱分析指标,分析了1961年以来云南冬春季、初夏及全年3个关键时段的降水量、潜在蒸散、水分盈亏量的年际变化特征、空间变化差异及突变特征、周期变化特征。结果表明:云南降水量、潜在蒸散量及水分盈亏量变化时空差异显著,冬春季常年水分亏缺,季节性干旱明显,全年和初夏总体水分盈余,但年际差异显著;1961年以来,云南冬春季、初夏和年降水量以及潜在蒸散量均呈减少趋势,由于变化速率差异较大,导致水分盈亏量呈现的变化趋势不一,年水分盈亏量呈减少趋势而冬春季和初夏水分盈亏量呈增加趋势;基于水分盈亏量的气象干旱评估指标可以较好的揭示云南气象干旱的阶段性和季节性变化特征,也能较好的体现21世纪以来气象干旱偏重的趋势,在气象干旱监测评估方面具有较好的应用前景。

In order to reveal the spatiotemporal evolution of drought in Yunnan,based on the Penman-Monteith method,the potential evapotranspiration of different periods and regions in Yunnan Province since 1961 were calculated.The difference between precipitation and potential evapotranspiration,i.e.,water budget,was used as a meteorological drought analysis index to analyze the inter-annual variation,spatial variation differences,mutation,and periodic variation characteristics of precipitation,potential evapotranspiration,and water budget.The results show that there are significant spatiotemporal and inter-annual differences in the changes of precipitation,potential evapotranspiration,and water budget in Yunnan.Water deficit in winter and spring is perennial,seasonal drought is obvious,and the overall water surplus in early summer is significant.Since 1961,the precipitation and potential evapotranspiration in winter,spring,early summer and each year have shown a decreasing trend.Due to the large differences in the change rate,the variation trend of water surplus and deficit is different.The annual water deficit showed a decreasing trend,while the water deficit in winter,spring,and early summer showed an increasing trend.The meteorological drought assessment index based on water budget can better reveal the characteristics of stages and seasonal changes of meteorological drought in Yunnan Province and the trend of meteorological drought since the turn of the century.It has a good application prospect in meteorological drought monitoring and evaluation.