三峡库区蓄水前后实际蒸散发时空变化及其与气象因子关系分析

Temporal and Spatial Changes of Actual Evapotranspiration and Its Relationship with Meteorological Factors in the Three Gorges Reservoir Area

为了探究三峡库区蒸散发(ET)时空特征及气候变化对库区蒸散发的影响,基于陆面模式CLM4.5对研究区实际蒸散发进行模拟分析,解析了三峡库区实际蒸散发的时空变化特征。通过相关分析法,分析了研究区内实际蒸散发与气候因子的关系。结果表明:(1)CLM4.5模型模拟的实际蒸散发与ET-MOD16呈正相关(R 2=0.91),能较好地反映研究区实际蒸散发的演变趋势;(2)ET具有明显的空间异质性,流域内ET在靠近干流范围逐渐变大,植被蒸腾在ET中所占比例最大;(3)时间尺度上,蓄水后ET较蓄水前有所增加,ET的年内变化具有典型的季节性,其中夏季>春季>秋季>冬季。三峡库区蓄水后较蓄水前实际蒸发量以及陆地蒸发量、植被蒸腾量均有所提升,植被蒸发量有所减少;并且年内ET与同期气温和降水量在整个研究区呈正相关关系,气温是影响三峡库区流域ET年内变化影响最大的气候因子。

In order to explore the temporal and spatial characteristics of evapotranspiration(ET)in the Three Gorges Reservoir area and the impact of climate change on it,based on the land surface model CLM4.5,the actual evapotranspiration in the study area was simulated and analyzed,and the temporal and spatial characteristics of the actual evapotranspiration in the Three Gorges Reservoir area were analyzed.We further analyzed the relationship between actual evapotranspiration and climate factors in the study area by using the correlation analysis method.It is found that:(1)the actual evapotranspiration simulated by the CLM4.5 model is positively correlated with ET-MOD16(R 2=0.91),which can reflect the needs of research on actual evapotranspiration in the study area in a good manner;(2)ET shows obvious spatial heterogeneity,ET in the watershed gradually increases when approaching the main streams,and vegetation transpiration accounts for the largest proportion of ET;(3)on the time scale,ET increases after water storage of the reservoir compared with before storage,ET presents a typical seasonality in its annual changes,and decreases in the order:summer>spring>autumn>winter.The actual evaporation,land evaporation,and vegetation transpiration have increased after the impoundment of the Three Gorges Reservoir area compared with those before the impoundment,and the vegetation evaporation has decreased.During a year,ET is positively correlated with the temperature and precipitation in the entire study area.Temperature is the climatic factor that has the greatest impact on the annual change of ET in the Three Gorges Reservoir area.