温度和水汽对土壤水动态影响的模拟研究

Simulation of the impacts of soil temperature and vapor on soil water dynamics

本文通过以Richards方程为基础的等温模型和以水汽热相互作用理论为基础的耦合模型分别对不同水位埋深条件下土水动态过程进行模拟。两种模型运行期都为一年,使用相同的大气强迫数据,计算结果进一步与蒸渗仪实测数据进行比较。结果表明等温模型存在旱季低估剖面含水量而雨季高估该值的计算偏差;而考虑了温度和水汽对土水运动影响的耦合模型,则可合理地预测出剖面含水量随降雨事件迅速增加以及雨后含水量缓慢减小的过程。耦合模型比等温模型更好地模拟出了地下水净补给量和土壤蒸发量的季节性变化过程。水位对地下水净补给量年累计值产生影响的极限深度为350cm,对土壤蒸发量年累计值产生影响的极限深度为150cm。

An isothermal model based on the Richards equation and a coupled model based on interaction between liquid water and water vapor transport have been conducted separately to simulate the dynamic process of soil water under different water table level conditions. For both models, the operating periods are one-year with the same atmospheric forcing data, and the simulated values were further compared with the observed data by lysimeters in Hanwang Hydrology and Water Resources Experimental Station in Xuzhou city. The results show that the isothermal model underestimated the soil water content during drought seasons while overestimated it during rainy seasons. On the other hand, the coupled model, which includes the impacts of soil temperature and water vapor on soil water dynamics, makes better predications on the seasonal variation of soil water content. The coupled model also makes predications of the seasonal variations in the groundwater recharge and soil water evaporation better than the isothermal model. The maximum water table depths which have impacts on the annual cumulative recharge and evaporation are 350 cm and 150 cm,respectively.