中文摘要：

本文系统综述了基于水文模型的蒸散发数据同化研究,阐述了蒸散发作为非状态变量构建数据同化演算关系的难点和瓶颈,并系统分析了利用当前各种通用水文模型进行蒸散发同化的可行性。基于此,尝试提出了一种易于操作且具有水循环物理机制的蒸散发同化新方案,该方案利用具有蒸散发—土壤湿度非线性时间响应关系的分布式时变增益模型（DTVGM）,并进一步完善DTVGM蒸散发机理,构建基于DTVGM水文模型的蒸散发数据同化系统。该新方案将为区域蒸散发精确模拟提供新的思路和借鉴。

英文摘要：

This paper provided a comprehensive review of evapotranspiration data assimilation based on hydrological model. The difficulty and bottleneck for ET was elaborated to construct data assimilation relationship as a non- state variable, with a discussion and analysis about the feasibility of various hydrological models to assimilate ET. Based on this, a new evapotranspiration assimilation scheme was proposed. The scheme presented developed an improved data assimilation system that use distributed time- variant gain model（DTVGM）which contains evapotranspiration- soil humidity nonlinear time response relationship.Moreover, the evapotranspiration mechanism in DTVGM was improved to perfect the ET data assimilation system.