Fractured aquifers sometimes underlie unconfined aquifers to form unconfined-fractured aquifer systems. The discharges of qanats constructed in such aquifer systems depend not only on the hydraulic parameters of the overlying aquifer but also on the hydraulic parameters of the underlying aquifer, where qanats can be approximated as constant-head slightly inclined horizontal wells. The available analytical solutions of the transient discharge variation of a qanat usually consider a single-layer unconfined aquifer and cannot be used to simulate the transient discharge variation of a qanat in an unconfined-fractured aquifer system. Thus, the goal of this work is to develop such an analytical model. The solution of the drawdown due to a point sink and the solution of the groundwater mound due to an areal recharge in an unconfined-fractured aquifer system are obtained using Laplace and Fourier transforms. These solutions are utilized to obtain the discharge variation of qanat in an unconfined-fractured aquifer system. By removing the inter-porosity flow term from the underlying fractured aquifer, the solution can be used to simulate the discharge variation of qanat in a two-layer aquifer or an aquifer-aquitard system. The effects of the hydraulic and geometric parameters of the underlying fractured aquifer on the discharge variation of qanat in an overlying, unconfined aquifer are explored. The solution can be utilized to predict the transient discharge of qanat due to rainfall or constant head horizontal well in an unconfined-fractured aquifer system; to estimate the hydraulic parameters of the underlying fractured aquifer using the discharge data of qanat or a horizontal constant-head well; to evaluate the response of qanat to areal recharge due to rainfall among other applications, thereby demonstrating the practical relevance and potential impact of our research on real-world hydrological problems.

中文翻译：

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在裂隙含水层下层的非承压含水层中临时排放坎儿井


裂隙含水层有时位于非承压含水层之下，形成非承压裂隙含水层系统。在这种含水层系统中建造的坎儿井的排放不仅取决于上覆含水层的水力参数，还取决于下层含水层的水力参数，其中坎儿井可以近似为恒定水头略微倾斜的水平井。坎儿井的瞬态流量变化的可用解析解通常考虑单层非承压含水层，不能用于模拟坎儿井在无承压裂隙含水层系统中的瞬态流量变化。因此，这项工作的目标是开发这样一个分析模型。在无承压裂隙含水层系统中，点沉导致的下降解和无承压裂隙含水层系统中面补给导致的地下水丘的解是使用拉普拉斯变换和傅里叶变换获得的。这些解用于获得坎儿井在无侧限裂隙含水层系统中的排放变化。通过从下面的裂缝含水层中去除孔隙间流动项，该解决方案可用于模拟两层含水层或含水层-滞水层系统中坎儿井的排放变化。探讨了下伏裂隙含水层的水力和几何参数对上覆、非承压含水层中坎儿井流量变化的影响。 该解决方案可用于预测由于降雨或无承压裂缝含水层系统中的恒定水头水平井而导致的坎儿井的瞬态排放;使用坎儿井或水平常水头井的排放数据估计底层裂隙含水层的水力参数;评估 QANAT 对降雨引起的区域补给的响应以及其他应用，从而展示我们的研究对现实世界水文问题的实际相关性和潜在影响。