Explain in details about the different types of material found in saturated formation.
Answers
All earth materials from soil to rocks have pore spaces. Although these pores are completely saturated with water below the water table from the groundwater utilization aspect only such material through which water moves easily and hence can be extracted with these are significant. On this basis the saturated formations are classified into four categories.
A) AQUIFERS: - An aquifer is a saturated formation of earth material, which not only stores water but yield it in sufficient quantity. Thus on aquifer transmits water relatively easily due to its high permeability. Unconsolidated deposits of sand and gravel form good aquifers.
B) AQUITARD: - It is a formation through which only seepage is possible and thus the yield is significant compared to an aquifer. It is partly permeable. e.g. sandy clay. Through an aquitard appreciable quantities of water may leak to an aquifer below it.
C) AQUICLUDE: - It is a geological formation, which is porous but not permeable. Such rocks may bear water but do not yield the same as they are impermeable. Argillaceous rocks like shale and clay are typical examples.
D) AQUIFUGE: - It is a geological formation, which is neither porous nor permeable. There are no interconnected openings and hence it cannot transmit water. Naturally these are not suitable for ground water occurrence. Massive granites and quartzite are typical examples.