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AN EXAMINATION OF THE MECHANISMS CONTROLLING GROUNDWATER GRADIENTS IN HYPER‐ARID REGIONAL SEDIMENTARY BASINS 1
Author(s) -
Lloyd John W.,
Miles John C.
Publication year - 1986
Publication title -
jawra journal of the american water resources association
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.957
H-Index - 105
eISSN - 1752-1688
pISSN - 1093-474X
DOI - 10.1111/j.1752-1688.1986.tb01902.x
Subject(s) - groundwater recharge , aquifer , geology , groundwater flow , groundwater , arid , sedimentary basin , hydrology (agriculture) , structural basin , depression focused recharge , sedimentary rock , dewatering , geomorphology , geochemistry , geotechnical engineering , paleontology
Although evidence of modern recharge in the North African and Arabian sedimentary basin aquifers exists, it is difficult to determine the volume of recharge. Also, from the evidence of regional groundwater gradients, the flow within the aquifers seems to be appreciably greater than one would intuitively expect. A hypotehtical model embodying the characteristics of the aquifers has been used to investigate the likely significance of various possible flow mechanisms. It is shown that while dewatering in the unconfined area can possibly contribute to flows for a considerable period of time, the maintenance of water levels in the unconfined zone must be the result of modern recharge. It is also shown that recharge depths of less than 10 mm per annum are sufficient given suitable aquifer parameters. Results for various combinations of aquifer parameters and configurations are given, including layered aquifers and the effects of restricted oufflows. Comparisons are made using a “bench mark” example. The work indicates that there is little point in carrying out conventional hydrological balance studies in hyper‐arid areas and that, instead, more emphasis should be placed upon good groundwater hydrographic data and modeling.