Journal of Agriculture, Science and Technology

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The effect of pumping water from wells in an aquifer

KG Warul, GX Stower, JK Sigey


Groundwater is sensitive to the climate change and agricultural activities in arid and semi-arid areas. Over the past several decades, human activities, such as groundwater extraction for irrigation, have resulted in aquifer overdraft and disrupted the natural equilibrium in these areas. This study reports research on the effect of pumping water from several wells in a given aquifer. We have considered, for simplicity, an idealized one layer aquifer which has been discretized into 49 identical blocks studied on the middle horizontal row of blocks. We have developed a numerical simulating model by discretizing the equation of continuity which we have converted into computer codes. A program has then been written. This program has successfully generated both hydraulic head and velocity profile distributions. The results reveal that there are less hydraulic head losses on pumpage from blocks which are far apart, the velocities being least in blocks which are far from the pumpage blocks. The results obtained have a high correlation with those from the well-known Theis equation for drawdown. The results would greatly help in limiting the usage of a given aquifer with respect to the maximum number of wells permissible in the aquifer as well as predict the levels of groundwater in a particular aquifer.

Key words: Aquifer, piezometric height, velocity profiles and simulation

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