Interactions between groundwater mounds caused by a geologic layer contrast affect the efficiency of managed aquifer recharge in arid areas. However, research has rarely examined the roles of groundwater mounding size variations on soil water dynamics in a stratified vadose zone in response to a sustained infiltration source. Numerical experiments were conducted on a two-dimensional vertical-section domain using HYDRUS software to simulate the behaviours of two adjacent (upper and lower) groundwater mounds underlying an infiltration basin subjected to clay loam and sandy alternately-layered soil profiles. The model successfully predicted the volume and extent of perched water and approximated vertical travel times during events generating downward fluxes from the surface injection. The response time of the mounding width (lateral extension) to the surface injection was delayed as compared to that of the mounding height (vertical extension), especially for the lower water mound. The mounding heights and widths show a strongly positive correlation with the infiltration rates of both high- and low-permeability layers where the injected water mounded, while the water storage amounts in the high- and low-permeability layers were governed by the mounding height and width, respectively. Exploratory simulations were then employed to assess the dependence of groundwater mounding behaviours and recharge performances on surface injection strategies. Results suggest that, by reducing injection rate or shortening injection duration, the near-term fraction of the surface injection converted to deep recharge is likely to be increased due to the narrowed groundwater mounding size, which would be limited by the water-retarding effect of layer contrasts. This study has important implications for predicting and understanding multilayered groundwater mounding behaviours and associated water mass balance under the geologic stratification, and is expected to aid in optimizing the infiltration basin operation for aquifer recharge.

中文翻译：

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多层地下水丘对补给盆地下水动力学的影响：地表注水的数值模拟和评估

地质层对比引起的地下水丘之间的相互作用会影响干旱地区受控含水层补给的效率。但是，研究很少研究响应连续的入渗源，分层渗流带中地下水堆积大小变化对土壤水分动力学的作用。使用HYDRUS软件在二维垂直截面域上进行了数值实验，以模拟浸润盆地下相邻的两个相邻（上部和下部）地下水丘在粘土壤土和砂质交替层状土壤剖面下的行为。该模型成功地预测了从地表注入产生向下通量的事件中栖息水的数量和范围以及近似的垂直传播时间。堆垛宽度（横向扩展）对表面注入的响应时间比堆垛高度（垂直扩展）的响应时间有所延迟，特别是对于下部水堆。围堰的高度和宽度与注入的水围成的高渗层和低渗层的渗透率呈极强的正相关关系，而高渗层和低渗层中的储水量则受围堰的高度和渗入度的控制。宽度。然后，采用探索性模拟方法来评估地下水堆填行为和补给性能对地表注入策略的依赖性。结果表明，通过降低注射速率或缩短注射时间，地表注水的缩水作用可能会限制地下水的堆积大小，因此转化为深层补给的地表注入的近期比例可能会增加。这项研究对于预测和了解地质分层下的多层地下水围堰行为及相关的水质平衡具有重要意义，并且有望有助于优化用于补给含水层的入渗盆地作业。