陆面实际蒸散研究

A Study on Actual Evaporation from Non-Saturated Surfaces

从能量平衡方程和热传导方程出发,引进"相对蒸散"和"相对干燥力",建立了用常规气象资料估算实际蒸散的理论模式。该模式避免了计算实际蒸散需首先计算可能蒸散这一过程,从而解决了由于采用不同的"可能蒸散"估算方法带来的误差。利用近30年的水文、气象等资料,在全国选择了九个有代表性的流域。对流域年实际蒸散量的模拟结果显示,除黄河流域部分年份外,可以将陆面年实际蒸散量的估算误差控制在10%以内。

Evaporation (Evapotranspiration) consumes much of the water and energy that is available on the ground of the earth and therefore influences all hydrological and most meteorological processes It also plays an important role for the water redistribution on the earth's surface and is a major determinant of the amounts in water cycle Instruments can only measure evaporation in research context for small areas, which are subject to intensive studies Therefore, there is a strong need for reliable methods that can estimate actual evaporation and require only a few meteorological parameters which are readily and routinely obtainable at standard weather stations Based on energy balance equation and mass transfer equation, a general model to estimate actual evaporation from nonsaturated surfaces was introduced Making use of two concepts,'relative evaporation' and 'relative drying power', a relationship was established to account for the departure from saturated conditions Using this model, the actual evaporation can be calculated without the need of potential evaporation estimation Furthermore, the model requires only a few meteorological parameters that are readily and routinely obtainable at standard weather stations Based on nearly 30 years of meteorological and hydrological data, in combined with GIS, nine representative river basins were selected Using the data of the selected river basins, the model was tested The results show that the actual evaporation rate can be estimated within an error of 10% in most area of China, except in few years in Yellow River Basin