Evaporation from both cracked and uncracked soil surfaces under moist conditions was measured as a function of near-surface wind speed, with wind speeds ranging between 0 and 5 ms⁻¹. Crack aperture width and distance between neighbouring cracks ranged from 2 to 20 mm and 40 to 120 mm, respectively, while crack depth was kept constant at 50 mm. Experiments were carried out in a wind tunnel with a 1 m × 1 m × 2.5 m test section, using large-scale (50 cm diameter, 15 cm depth) soil samples. Sixty-six combination of crack properties and wind speed were considered. Resulting evaporation data were used to assess the shape of the relationships between evaporation rate, wind speed conditions and crack properties. A semiempirical model for estimating evaporation from cracked soil, as a function of wind speed, crack width and crack distance, given evaporation as a function of wind speed from uncracked soil, was developed. Results showed that evaporation from cracked soil under moist conditions increased by 60%–65% compared to uncracked soil, for the wind speed and crack properties given above. Evaporation from crack apertures was up to eight times higher than from an uncracked surface under the same wind conditions. Results further indicated that for constant wind speed and crack distance, there exists a crack width at which evaporation from the soil is at maximum. The semiempirical model based on exponential and power function relationships, was able to very closely match the experimental data and is further expected to be able to approximate evaporation under natural conditions.

中文翻译：

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基于近地表风速、裂缝宽度和裂缝距离预测潮湿、开裂土壤的蒸发

潮湿条件下破裂和未破裂土壤表面的蒸发量是近地表风速的函数，风速范围在 0 到 5 ms ^-1之间. 裂纹孔径宽度和相邻裂纹之间的距离分别为 2 到 20 毫米和 40 到 120 毫米，而裂纹深度保持在 50 毫米不变。实验在风洞中进行，测试截面为 1 m × 1 m × 2.5 m，使用大型（直径 50 cm，深度 15 cm）土壤样品。考虑了裂纹特性和风速的 66 种组合。得到的蒸发数据用于评估蒸发速率、风速条件和裂缝特性之间关系的形状。开发了一种半经验模型，用于估算裂缝土壤的蒸发量，作为风速、裂缝宽度和裂缝距离的函数，假设蒸发量是未裂缝土壤的风速的函数。结果表明，对于上述风速和裂缝特性，与未开裂土壤相比，潮湿条件下开裂土壤的蒸发量增加了 60%–65%。在相同的风力条件下，裂纹孔的蒸发量比未裂纹表面的蒸发量高 8 倍。结果进一步表明，对于恒定的风速和裂缝距离，存在一个裂缝宽度，在该宽度处土壤蒸发量最大。基于指数和幂函数关系的半经验模型能够非常接近地匹配实验数据，并进一步预计能够在自然条件下近似蒸发。结果进一步表明，对于恒定的风速和裂缝距离，存在一个裂缝宽度，在该宽度处土壤蒸发量最大。基于指数和幂函数关系的半经验模型能够非常接近地匹配实验数据，并进一步预计能够在自然条件下近似蒸发。结果进一步表明，对于恒定的风速和裂缝距离，存在一个裂缝宽度，在该宽度处土壤蒸发量最大。基于指数和幂函数关系的半经验模型能够非常接近地匹配实验数据，并进一步预计能够在自然条件下近似蒸发。