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Author |
Sedghi, M.M.; Zhan, H. |
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Title |
On the discharge variation of a qanat in an alluvial fan aquifer |
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Journal Article |
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Year |
2022 |
Publication |
Journal of Hydrology |
Abbreviated Journal |
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Volume |
610 |
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Pages |
127922 |
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Keywords |
Analytical solution, Wedge-shaped aquifer, Image well, Areal recharge |
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Abstract |
Qanat is a passive (unpumped) horizontal well (or a slant well with a very mild inclined angle) that is capable of extracting water from aquifers by gravity. Many qanats are constructed along the radius of the alluvial fan wedge-shaped aquifers. Analytical modeling of such a qanat-aquifer system provides great benefit for quickly screening different designs of qanats and accessing the performance of qanat discharge in the field. The previous analytical modeling of discharge of qanats, however, did not consider the wedge-shaped aquifers. Thus, the goal of this research is to obtain semi-analytical solutions of discharge variations of qanats in alluvial fan aquifers with nearby pumping wells, subjected to areal recharges due to rainfall. The uniform head boundary is considered inside the qanat (because of its enormous permeability in respect to the background aquifer). The influences of the aquifer lateral boundaries on discharge of qanat and its sensitivity to hydraulic and geometric parameters are explored. The influences of the lateral boundaries on the discharge of qanat due to areal recharge and nearby pumping wells discharge are also explored. The results of this study can be utilized for multiple purposes: 1) to predict the discharge of qanat in an alluvial fan aquifer and explore the influences of the areal recharge and nearby pumping well discharge; 2) to estimate the hydraulic parameters of the alluvial fan aquifer depleted by a qanat; 3) to determine the location of the nearby pumping well to minimize its influences on the discharge of a qanat; 4) to calculate the water budgets of aquifers depleted by qanats and pumping wells and replenished by areal recharge among other applications. This paper is an extension to the work presented by Sedghi and Zhan (2020) (which concerns an infinite unconfined aquifer) for an unconfined alluvial fan aquifer setting. |
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0022-1694 |
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THL @ christoph.kuells @ Sedghi2022127922 |
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267 |
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Author |
Sedghi, M.M.; Zhan, H. |
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Title |
Semi-analytical solutions of discharge variation of a qanat in an unconfined aquifer subjected to general areal recharge and nearby pumping well discharge |
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Journal Article |
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Year |
2020 |
Publication |
Journal of Hydrology |
Abbreviated Journal |
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Volume |
584 |
Issue |
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Pages |
124691 |
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Keywords |
Analytical solution, Laplace domain, Screen segmentation, Qanat, Areal recharge, Constant head |
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Qanat is a type of drain that extract water from aquifers by gravity. Significant amount of fresh water used in Middle East and other parts of the world are supplied by qanats. Despite their importance, discharge variation of these type of wells received almost no attention. The aim of this research is to obtain a Laplace domain solution of discharge variation of a qanat installed in an anisotropic unconfined aquifer subjected to arbitrary areal recharge and nearby pumping well(s) discharge. A new semi-analytical solution of drawdown is obtained first to implement the effects of arbitrary areal recharge and nearby pumping well(s) using the principle of superposition. Then, the discharge variation solution of the qanat is obtained from the drawdown solution. To establish a constant-head boundary condition at the qanat periphery, the qanat is discretized into several segments. The results of this study are presented in dimensionless discharge-dimensionless time curves. The effects of hydraulic as well as geometric parameters on the discharge variation of the qanat due to arbitrary areal recharge, falling of water table from its initial position and discharge of nearby wells are explored. We also investigate the influences of distance and screen depth and location of the nearby well on the discharge variation of the qanat. The results of this study can be utilized for multiple purposes: 1) to predict discharge of qanat in response to rainfall and nearby pumping well(s); 2) to estimate the aquifer parameters using hydrograph of the qanat; 3) to determine optimal location and pumping pattern of the nearby wells to minimize their influences on the discharge of the qanat; 4) to calculate water budget of aquifers drained by a qanat. The equation presented in this work can also be used to estimate discharge of a horizontal drain installed in cropland subjected to arbitrary irrigation pattern. |
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0022-1694 |
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THL @ christoph.kuells @ Sedghi2020124691 |
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261 |
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Schwiede, M.; Duijnisveld, W.H.M.; Böttcher, J. |
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Investigation of processes leading to nitrate enrichment in soils in the Kalahari Region, Botswana |
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Journal Article |
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2005 |
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Physics and Chemistry of the Earth, Parts A/B/C |
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30 |
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11 |
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712-716 |
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Nitrate, Arenosol soils, Semi-arid, Kalahari, Cattle, Chloride, Travel time |
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In Southern Africa elevated nitrate concentrations are observed in mostly uninhabited semi-arid areas. In the Kalahari of Botswana groundwater locally exhibits concentrations up to 600mg/l. It is assumed, that nitrate found in the groundwater originates mainly from nitrogen input and transformations in the soils. Our investigations in the Kalahari between Serowe and Orapa show that cattle raising is an important source for enhanced nitrate concentrations in the soils (Arenosols). But also in termite mounds very high nitrate stocks were found, and under natural vegetation (acacia trees and shrubs) nitrate concentrations were mostly unexpectedly high. This nitrate enrichment in the soils poses a serious threat to the groundwater quality. However, calculated soil water age distributions in the unsaturated zone clearly show that today’s nitrate pollution of the groundwater below the investigation area could originate from natural sources, but cannot be caused by the current land use for cattle raising. |
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1474-7065 |
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Integrated Water Resources Management (IWRM) and the Millennium Development Goals: Managing Water for Peace and Prosperity |
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Call Number |
THL @ christoph.kuells @ Schwiede2005712 |
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276 |
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Author |
Salbu, B. |
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Preface: uranium mining legacy issue in Central Asia |
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2013 |
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Journal of Environmental Radioactivity |
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123 |
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1-2 |
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0265-931x |
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THL @ christoph.kuells @ salbu_preface_2013 |
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125 |
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Saini, K.; Singh, P.; Bajwa, B.S. |
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Title |
Comparative statistical analysis of carcinogenic and non-carcinogenic effects of uranium in groundwater samples from different regions of Punjab, India |
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Journal Article |
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2016 |
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Applied Radiation and Isotopes |
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118 |
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196-202 |
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Carcinogenic, Groundwater, LED fluorimeter, Uranium |
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LED flourimeter has been used for microanalysis of uranium concentration in groundwater samples collected from six districts of South West (SW), West (W) and North East (NE) Punjab, India. Average value of uranium content in water samples of SW Punjab is observed to be higher than WHO, USEPA recommended safe limit of 30µgl−1 as well as AERB proposed limit of 60µgl−1. Whereas, for W and NE region of Punjab, average level of uranium concentration was within AERB recommended limit of 60µgl−1. Average value observed in SW Punjab is around 3–4 times the value observed in W Punjab, whereas its value is more than 17 times the average value observed in NE region of Punjab. Statistical analysis of carcinogenic as well as non carcinogenic risks due to uranium have been evaluated for each studied district. |
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0969-8043 |
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THL @ christoph.kuells @ saini_comparative_2016 |
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130 |
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