Analysis of the radial flow from a groundwater reservoir to its production well in steady state flow conditions in Monzoungoudo Benin.

Abstract

Background:Analyze the groundwater flow is generally to predict the aquifer piezometry under various groundwater stress situations. This paper aimsto analyzetheradial flow, between the groundwater reservoir and its production well, which consequence is the appearance ofthe drawdown curve(cone of depression),in the potentiometric surface caused by the pumping well.When a well is producing, water levels in its neighborhood are lowered. After a certain producing time, with a constant flow, the drawdown cone does not evolve. In this case, the permanentregime of groundwater flow is reached and do not change. It means that the pressure and the fluidvelocity distributions are independent of time; therefore,we consider that the drawdown curve (cone of depression) in the potentiometric surface is timeless in the permanent regime.C. V. Theis developed in 1935, an approach of solution which investigate the behavior of the lowering of the piezometric surface cone generated by the discharge of the pumping well using the groundwater storage.This study, which result presented a simple analytical model behind the calculation of the drawdown cone (cone of depression) in the potentiometric surface, is a refinements of the so-called Theis equation.(See figure n°1).Objective: Determination and calculation of the static pressure; the determination of mathematical expression and the calculation of the drawdown curve in the potentiometric surface.Results:the expression of static pressure of the reservoir is established and calculated.The mathematical expression of the discharge of hydraulic charge (the drawdown cone in the potentiometric surface) from the reservoir to the well is established.The drawdown curve in the potentiometric surface is drawn.Conclusion:The mathematical model, developed to analyze the groundwater flow between the producing well and the reservoir, showed that the fall of the hydraulic load occurs essentially in the vicinity of the producing well,and refine the equationofC. V. Theis. It permits to watch the groundwater storage, to control the piezometric lowering on the catching fields or the draining or drying excavations, to do the diagnostics in water borings, or oil or gas drillings.