Groundwater Geology and Geological Prospecting
To explore groundwater in area, the groundwater geology must be well understood by the process of remote sensing, geological mapping, and hydrogeological investigation, and finally, geophysical method is used to delineate subsurface aquifer dispositions h
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Groundwater Geology and Geological Prospecting
Abstract To explore groundwater in area, the groundwater geology must be well understood by the process of remote sensing, geological mapping, and hydrogeological investigation, and finally, geophysical method is used to delineate subsurface aquifer dispositions horizontally and vertically in a particular geological structure and to assess aquifer property, water quality, etc. Hydrogeological cycle is the process of precipitation, run-off, groundwater flow, evaporation and transpiration. Thus, groundwater is a part of the cycle in the upper lithosphere. It is observed from different studies that sedimentary rocks are most prospective from groundwater point of view compared to igneous and metamorphic formation. Limestone cavities serve as reservoirs for water storage. This is carbonate aquifers. Basaltic lava flows have sometimes been found to be serving as good aquifer. The types of aquifers (confined and unconfined), water table, aquitard, aquiclude, aquifuge, etc., should be well understood for groundwater geology. To determine the aquifer parameters, pumping test should be carried out and storage coefficient and transmissivity are calculated from time–drawdown curve. Hence, it is understood that from geological background, geophysical investigation is done, and on the basis of idea of aquifers, drilling is done. After drilling with the help of geophysical logging, the actual depths of aquifers are known and strainers are fitted. Finally after pump tests, the aquifer characteristics are known and thereby water wells are prepared.
Keywords Geological map Hydrogeological investigation Hydrogeological cycle Aquiclude Aquifuge Aquitard Precipitation Run-off Lithosphere Confined Aquifer Limestone cavity Water table Water well
3.1
Introduction
Groundwater geology must be understood well before geological prospecting methods can be used scientifically in the exploitation of groundwater. Several textbooks are available (Todd 1995; Karanth 1995; Domenico and Schwartz 1990,
© Springer Science+Business Media Singapore 2016 H.P. Patra et al., Groundwater Prospecting and Management, Springer Hydrogeology, DOI 10.1007/978-981-10-1148-1_3
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3 Groundwater Geology and Geological Prospecting
for example) giving geological and hydrogeological processes, in detail. Prospecting for groundwater should sequentially consist of the following steps: (i) Remote sensing (Chap. 2) comprising use of satellite images for hydrogeomorphic mapping of the terrain, lineament mapping and shallow groundwater potential zone mapping; (ii) Geological methods for lithological and structural mapping and for fracture trace analysis; (iii) Hydrogeological investigations are used for lithological classification with respect to hydrologic properties, hydraulic continuity in relation to geologic structures and location of springs; (iv) Surface geophysical methods (Chap. 4) are used to delineate the subsurface distribution of formations. Subsurface well-logging technique
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