基于互补相关的乌江流域实际蒸散量分布式模拟

Distributed Modeling of Actual Evapotranspiration in Wujiang River Drainage Basin Based on Complementary Relationship

为了提高气候变化下估算乌江流域陆面实际蒸散量的精度,利用乌江流域气象和水文数据,在蒸散互补原理基础上建立用常规气象资料估算流域实际蒸散量的模型。模拟结果显示:该模型能将乌江流域多年平均实际蒸散量的相对误差控制在5%以内;在充分考虑地形起伏等下垫面不均匀的条件下,将估算模型中各分量的分布式模拟结果与估算模型耦合,实现了乌江流域实际蒸散量的分布式模拟;该模型更加精细地表现了流域实际蒸散量的空间变化情况,发现其在空间分布上呈显著的西高东低的分布趋势;在时间变化上,1961—2010年间乌江流域实际蒸散量在总体上表现为下降趋势,降幅为5.08 mm/(10 a),但是2000年以后实际蒸散量有较为明显的上升趋势;日照时数及相对湿度的上升是造成实际蒸散量产生以上变化的主要原因。研究结果可为水资源评价、农业气候区划制定等提供参考。

To improve the accuracy of estimating actual evapotranspiration of land surface in Wujiang River drainage basin under climate change,a model of estimating the actual evapotranspiration of the basin based on conventional meteorological data was established.The simulation results manifested that the relative error of the estimated evapotranspiration in Wujiang River drainage basin can be controlled within 5%.The components of the model can be simulated in distributed approach.The heterogeneity of land surface such as topography and land cover diversity was considered in the simulation.Moreover,the simulation results also demonstrated the spatial and temporal variations of the actual evapotranspiration in the basin more detailedly:in spatial scale,evapotranspiration was very low in the east of the basin and evidently high in the west;in temporal scale,the actual evapotranspiration displayed a trend of decreasing during 1961-2010 in a rate of 5.08 mm/(10 a),and an apparent rising trend after 2000.The increment of sunshine hours and relative humidity are main causes of the aforementioned changes.The research results could offer reference for water resources evaluation and agricultural climate zoning.