基于K_(c)和NDVI关系的蒸散发量空间尺度提升及时空变化  

Spatial scaling up and spatiotemporal variation of evapotranspiration based on Kc and NDVI

作　　者：李建柱[1] 逯清 张婷[1] 张博 康彦付 LI Jianzhu;LU Qing;ZHANG Ting;ZHANG Bo;KANG Yanfu(State Key Laboratory of Hydraulic Engineering Simulation and Safety,Tianjin University,Tianjin 300350,China;Xingtai Hydrology Survey and Research Center,Xingtai 054000,China)

机构地区：[1]天津大学水利工程仿真与安全国家重点实验室,天津300350 [2]河北省邢台水文勘测研究中心,河北邢台054000

出　　处：《南水北调与水利科技（中英文）》2023年第3期417-426,共10页South-to-North Water Transfers and Water Science & Technology

基　　金：国家自然科学基金项目(52079086,52279022)。

摘　　要：为探究流域长时序高空间分辨率蒸散发量计算对区域水资源开发利用、水利工程规划设计及农业可持续发展的重要意义,以河北省邢台市柳林流域为研究对象,基于Penman-Monteith模型和蒸渗仪实测蒸散发数据计算不同时期的流域作物系数(Kc),并建立Kc与归一化植被指数(normalized difference vegetation index,NDVI)的关系,利用250 m分辨率NDVI产品将蒸渗仪测算的蒸散发量升尺度到柳林流域,计算流域各网格2000—2021年的蒸散发量,分析蒸散发量的时空变化规律。结果表明:柳林流域多年平均潜在蒸散发量为1135.6 mm,呈下降趋势;多年平均蒸散发量为591.4 mm,呈上升趋势。蒸散发量在空间上西北高东南低,四季蒸散发量空间分布特征与多年平均蒸散发量一致,且季节上分配不均。基于NDVI估算的蒸散发量与水量平衡法计算的蒸散发量2000—2020年多年平均相对误差为7.9%,说明利用Kc与NDVI关系可以较精确地对蒸散发量进行空间尺度提升。In the catchment scale,evapotranspiration refers to the sum of evaporation from water surface and soil,and transpiration of vegetation in a specific region.Evapotranspiration can reflect heat exchange and water exchange between land and atmosphere,and is an important element in hydrological cycle.Therefore,the study of evapotranspiration variation is of great significance to investigate the law of water cycle,the planning and design of hydraulic engineering,and the efficient utilization of water resources.Due to the short time series of evapotranspiration observation,the small number of observation stations,and the heterogeneity of underlying surface at catchment scale,the spatial-temporal distribution of evapotranspiration can not be obtained using the measured data.Scaling up the observed short-term evapotranspiration data at a small scale is an efficient way to get long-term time series at regional scale.To this end,Liulin watershed was selected as the study area in which a large lysimeter was installed in 2021.Penman-Monteith model is a method for calculating reference crop evapotranspiration(ET0)determined by FAO based on the energy balance and water-air diffusion theory,and was employed in the Liulin watershed.Combined with the measured evapotranspiration(ETc)by the lysimeter from June 2020 to May 2021,the crop coefficient(Kc)was calculated by the equation ETc=Kc×ET0.Studies have shown that crop coefficient(Kc)has a good linear correlation with normalized vegetation index(NDVI),and this relationship has also been used to study evapotranspiration in ecosystems with different crop types and uneven underlying surface.The linear relationship between Kc obtained by the lysimeter and NDVI was established based on the data from June 2020 to May 2021.Then the Kc with the grid size of 250 m was scaled up to Liulin watershed scale from 2000 to 2021 according to the spatial NDVI distribution from 2000 to 2021.Finally,the evapotranspiration with the same spatial and temporal resolution as NDVI in Liulin watershed was

关 键 词：蒸散发空间尺度提升 Penman-Monteith模型 作物系数 归一化植被指数 空间分布 

分 类 号：TV213[水利工程—水文学及水资源]