5.14.1. Causes of Waterlogging
Ground water reservoirs receive their supplies through percolation of water from the ground surface. This water may be from rainfall, from lakes or water applied to the fields for irrigation. This water percolates down to the water table and, thus, raises its position. Depending upon the elevation and the gradient of the water table, the flow may either be from surface to the ground (i.e., inflow) or ground to the surface (i.e., outflow). Outflow from a ground water reservoir includes water withdrawn through wells and water used as consumptive use. An overall balance between the inflow and outflow of a ground water reservoir will keep the water table at almost fixed level. This balance is greatly disturbed by the introduction of a canal system or a well system for irrigation. While the former tends to raise the water table, the latter tends to lower it.
Waterlogging in any particular area is the result of several contributing factors. The main causes of waterlogging can be grouped into two categories: (i) natural, and (ii) artificial.
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