Drywells are widely used as managed aquifer recharge devices to capture stormwater runoff and recharge groundwater, but little research has examined the role of subsurface heterogeneity in hydraulic properties on drywell recharge efficiency. Numerical experiments were therefore conducted on a 2D-axisymmetric domain using the HYDRUS (2D/3D) software to systematically study the influence of various homogenous soil types and subsurface heterogeneity on recharge from drywells under constant head conditions. The mean cumulative infiltration (μI) and recharge (μR) volumes increased with an increase in the saturated hydraulic conductivity (Ks ) for various homogeneous soils. Subsurface heterogeneity was described by generating ten stochastic realizations of soil hydraulic properties with selected standard deviation (σ), and horizontal (X) and vertical (Z) correlation lengths. After 365 days, values of μI, μR, and the radius of the recharge area increased with σ and X but decreased with Z. The value of μR was always smaller for a homogeneous than a heterogeneous domain. This indicates that recharge for a heterogeneous profile cannot be estimated with an equivalent homogeneous profile. The value of μR was always smaller than μI and correlations were highly non-linear due to vadose zone storage. Knowledge of only infiltration volume can, therefore, lead to misinterpretation of recharge efficiency, especially at earlier times. The arrival time of the wetting front at the bottom boundary (60 m) ranged from 21-317 days, with earlier times occurring for increasing σ and Z. The corresponding first arrival location can be 0.1-44 m away from the bottom releasing point of a drywell in the horizontal direction, with greater distances occurring for increasing σ and X. This knowledge is important to accurately assess drywell recharged performance, water quantity, and water quality.

中文翻译：

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在恒定水头条件下从干井补给地下水

干井被广泛用作管理含水层补给装置，以捕获雨水径流和补给地下水，但很少有研究检查地下异质性对干井补给效率的水力特性的作用。因此，使用 HYDRUS (2D/3D) 软件在 2D 轴对称域上进行了数值实验，以系统地研究各种同质土壤类型和地下异质性对恒定水头条件下干井补给的影响。对于各种均质土壤，平均累积入渗 (μI) 和补给 (μR) 体积随着饱和导水率 (Ks) 的增加而增加。通过生成十个具有选定标准偏差 (σ) 的土壤水力特性的随机实现来描述地下异质性，以及水平 (X) 和垂直 (Z) 相关长度。365 天后，μI、μR 和补给区半径的值随 σ 和 X 增加但随 Z 减小。均质域的 μR 值始终小于异质域。这表明异质剖面的补给不能用等效的均质剖面来估计。μR 的值总是小于 μI，并且由于包气带存储，相关性是高度非线性的。因此，仅了解渗透量会导致对补给效率的误解，尤其是在早期。底部边界（60 m）润湿锋的到达时间为21-317天，随着σ和Z的增加出现更早的时间。相应的初到位置可以为0。