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Cost effectiveness in well site selection methods in a fractured aquifer

Taylor, K.C., Minor, T.B., Chesley, M.M., Matanawi, K.
Ground water 1999 v.37 no.2 pp. 271-274
aquifers, wells, rocks, spatial variation, aerial photography, geology, image analysis, vegetation, topography, cost effectiveness, Ghana
In regions where ground water flow is restricted to sparse, narrow fractures, productive and nonproductive drilling sites frequently are separated by only a few tens of meters. Drilling success rates are low in these areas because favorable drilling sites occur infrequently and are difficult to identify. The drilling success rate can be increased when imagery and surface geophysics are incorporated into the site selection method. We present a method to evaluate the economic benefit of various site selection methods and show that the use of surface geophysics and aerial photography can reduce drilling costs by approximately a factor of two in an area with a low drilling success rate that is characterized by narrow fracture zones covered with several meters of weathered clays and thick vegetation. The benefits are smaller and less certain when social considerations are a strong factor in site selection.