Salt‐Water Upconing in an Aquifer Overlain by a Leaky Confining Bed

Abstract

Salt‐water upconing that occurs in an aquifer overlain by a leaky confining bed is described in terms of an analytical model that assumes the existence of a sharp interface between the fresh water and salt water and the occurrence of a critical rise in the interface, above which only an unstable cone can exist. Drawdown is calculated along the salt‐water/fresh‐water interface due to pumping from a well that partially penetrates the fresh‐water zone, and then the Ghyben‐Herzberg relation is used to calculate the steady‐state rise in the interface, which is assumed to be small compared to the thickness of the aquifer. The interface rise and the critical pumping rate (Qc) are determined in terms of aquifer and confining bed properties and the degree of penetration of the pumping well into the fresh‐water zone. The critical rise is assumed to occur when the interface rise is equal to 0.3 times the distance from the original interface location to the bottom of the well. Based on the analytical model, the nondimensional critical pumping rate increases as the ratio of vertical to horizontal hydraulic conductivity (Kz/ Kr) is decreased, and it decreases as the degree of well penetration (t/b) is increased. As an example application, Qc was calculated using site‐specific data from a test well in Pasco County, Florida. A value of Qc= 4.28 × 105 cubic feet per day was determined by assuming that Kz/Kr= 1.0. If Kz/Kr were subsequently determined to be less than or greater than 1.0, then the estimated value of Qc would be increased or decreased, respectively.

Effects of Urbanization on Groundwater

“…This is a widespread problem that is also observed in coastal aquifers in several states in the USA including Georgia (ASCE, 1969;Krause and Clarke, 2001) as well as globally in other countries. The solution of this EFFECTS OF URBANIZATION ON GROUND WATER problem has been attempted using a sharp interface model (Motz, 1992) or the variable density flow analysis approach as discussed above and also in (Reilly, Frimpter et al, 1987;. The most recent work on this line of research is by (Oswald and Kinzelbach, 2004).…”

Modelisation de saumures carbonatees par le traitement multivariable en hydrogeochimie a la mine Niobec de Saint-Honore (Quebec)

“…Normalement, l'interface est sous la forme d'une zone de transition plus ou moins épaisse à cause de la dispersion hydrodynamique des fluides miscibles (Motz, 1992). C'est le cas aussi à la mine où la concentration en sel devient de plus en plus élevée avec la D'autres auteurs suggèrent une origine intérieure (autochtone) Gascoyne et al, 1987;Kamineni, 1987;Edmunds et al, 1984Edmunds et al, , 1985 Les processus hydrogéochimiques associés aux eaux souterraines ont été identifiés à l'aide des corrélations du chlore, élément conservateur, avec les autres éléments majeurs.…”

Steady critical discharge rates from vertical and horizontal wells in fresh–saline aquifers with sharp interfaces

“…Many investigators studied flow potential around a pumping well in a saline-freshwater aquifer utilizing analytical methods (Strack 1989;Motz 1992Motz , 1995Panday et al 1993;Cheng and Quazar 1999;Mantoglou 2003). Also, researchers have considered saline-freshwater interface upconing below a water well in many studies (Dupuit 1863;Muskat 1937;Bear and Dagan 1964;Wang 1965;Dagan and Bear 1968;Schmorak and Mercado 1969;Chandler and McWhorter 1975;Haubold 1975;Freeze and Cherry 1979;Panday 1995;Bower et al 1999;Fetter 2001;Simmons et al 2002;Todd and Mays 2005;Nordbotten and Celia 2006;Fass et al 2007).…”