淮北平原气象因素对裸地潜水蒸发的影响

【目的】理清气象因素对潜水蒸发的影响。【方法】采用五道沟水文实验站62套原状土蒸渗仪及气象场1991─2015年长系列实验资料,分析了潜水蒸发与水面蒸发、气温、降雨及地温的关系,并比较了气象因素对砂姜黑土与黄潮土潜水蒸发量影响的差异。【结果】砂姜黑土与黄潮土地下水埋深为0时的潜水蒸发均比水面蒸发小,且都与水面蒸发呈线性相关关系(R~2>0.9)。潜水蒸发与气温年内变化趋势基本一致,气温对砂姜黑土在地下水埋深小于0.2 m影响较大,大于0.4 m影响较小;对黄潮土在地下水埋深小于1.0 m影响较大,大于2.0 m影响较小。地温是潜水蒸发的能量来源之一,5—8月,潜水蒸发随地温的增加而增大;11月—次年2月,潜水蒸发随地温的增加而减小,而3、4月和9、10月处于转折阶段,规律性不明显。对多年平均月潜水蒸发与地温进行曲线拟合,采用高斯曲线拟合最好(R~2均大于0.9)。【结论】气象因素对地下水埋深浅的潜水蒸发影响明显,且对黄潮土的影响大于砂姜黑土,可用地温计算潜水蒸发。

Metrological Factors Affecting Evaporation of Shallow Groundwater in the Absence of Plants in Huaibei Plain

【Objective】Groundwater evaporation is a main process in hydrological cycle, and the objective of this paper is to unveil the main metrological factors that profoundly impact shallow groundwater evaporation in the absence of plants.【Method】The experiment was conducted in 62 lysimeters filled with intact fluvo-aquaic soil and lime concretion black soil respectively. Data measured from 1991 to 2015 were used to analyze groundwater evaporation in response to surface water evaporation, ground-surface temperature and rainfall, from which we identified the most influential factors.【Result】Groundwater evaporation from both soils was proportional to surface water evaporation with R~2>0.9, and was closely related to intra-annual temperature fluctuation. For groundwater in the lime concretion black soil, the impact of temperature on its evaporation was significant when groundwater table was shallower than 0.2 m depth and became less noticeable when groundwater table dropped to 0.4 m deep. For fluvo-aquaic soil, the temperature had considerable impact when the depth of groundwater table was above 1.0 m and the impact decreased as groundwater table dropped to 2.0 m deep. From May to August, the evaporation increased with ground-surface temperature, while during the following November to February it decreased as ground-surface temperature increased. March, April, September and October were turning points during which there was no close relationship between ground-surface temperature and groundwater evaporation.Both monthly average groundwater evaporation and ground-surface temperature were normally distributed with R~2 being 0.9.【Conclusion】Groundwater evaporation from the fluvo-aquic soil was affected by meteorological factors more than from the lime concretion black soil, and for both soils it was closely related to the ground-surface temperature.