Groundwater artificial recharge and medium characteristics represent the major factors in controlling the groundwater flow processes in managed aquifer recharge areas. According to the depositional features of alluvial fans, an analogous homogeneous phreatic sand tank aquifer and the corresponding inhomogeneous scale numerical models were established to investigate the groundwater flow under the combined influence of artificial recharge (human activities) and decaying hydraulic conductivity (medium characteristics). In this study, groundwater flow through a managed aquifer recharge area in an alluvial fan was analyzed under the conditions of decaying hydraulic conductivity (K) with depth or length from apex to apron. The results showed that groundwater flow processes induced by artificial recharge were significantly controlled by the increasing decay exponents of K. The decaying K with depth or length in alluvial fan areas expanded the degree of influence of artificial recharge on groundwater flow. With the increase of decay exponents, the flow directions gradually changed from a horizontal to vertical direction. Groundwater age and spatial variability could also be increased by the increasing decay exponents. The residence time distributions (RTDs) of ambient groundwater and artificially recharged water exhibited logarithmic, exponential, and power law behavior. Penetration depth and travel times of ambient groundwater flow could be affected by artificial recharge and decay exponents. Furthermore, with the increase of decay exponents, the thickness of the artificially recharged water lens and travel times of artificially recharged water were increased. These findings have important implications for the performance of managed aquifer recharge in alluvial fan areas as well as the importance of considering the gradual decrease of K with depth and length.

中文翻译：

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水力传导率衰减对冲积扇管理含水层补给区地下水流动过程的影响

地下水人工补给和介质特性是控制含水层补给区地下水流动过程的主要因素。根据冲积扇的沉积特征，建立了类似的均质潜水砂池含水层和相应的非均质比例数值模型，研究了人工补给（人类活动）和导水率衰减（介质特性）共同影响下的地下水流动。在这项研究中，在水力传导率 (K) 随从顶点到围裙的深度或长度衰减的条件下，分析了流经冲积扇中受管理的含水层补给区的地下水流。结果表明，人工补给引起的地下水流动过程受K衰减指数增加的显着控制。冲积扇区K随深度或长度的衰减扩大了人工补给对地下水流动的影响程度。随着衰减指数的增加，流动方向逐渐从水平方向变为垂直方向。地下水年龄和空间变异性也可能因衰减指数的增加而增加。周围地下水和人工补给水的停留时间分布 (RTD) 表现出对数、指数和幂律行为。周围地下水流的渗透深度和传播时间可能受人工补给和衰减指数的影响。此外，随着衰减指数的增加，增加了人工补给水透镜的厚度和人工补给水的传播时间。这些发现对冲积扇区含水层补给管理的性能以及考虑 K 随深度和长度逐渐减少的重要性具有重要意义。