Role of Geological and Geophysical Surveys in Tube-well Schemes for Anti-Waterlogging

Of the various anti-waterlogging measures, pumping by tube-wells is considered to be a quick and a direct method. It removes waterlogging in comparatively short periods and is best done by shallow tube-wells.

For the installation of shallow tube-wells there are certain bare minimum conditions which have to be fulfilled such as that at least 40 ft. to 45 ft. (12.2 m. to 13.7 m.) thickness of good water-bearing strata is available in a depth of 65 ft. (19-8 m.) below natural surface and that it is not stratified. If water-bearing strata is stratified and is intercepted by clay bands, the vertical drainage is considerably impaired and required results in regard to lowering of sub-soil water-levels are not attained. Therefore, before any drainage scheme by pumping is prepared or undertaken it becomes imperative to conduct geological survey of the project area and ensure that required thickness of water-bearing strata and good quality of ground water are available at shallow depths, etc. Unless this is done before hand, schemes can prove unsuccessful and result in wasteful expenditure. Thus geological survey for the preparation of drainage schemes by pumping is a ‘Must’.