Question

Water harvesting. List two advantage at community level and two causes for failure of availability of ground water

Answer 1

Excessive withdrawal of groundwater coupled by significant de- crease in recharge contributes to the problem. The extent of saline water intrusion is influenced by nature of geological settings, hydraulic gradient, rate of groundwater withdrawal and its recharge (Choudhury et al. 2001). In studying the thickness and geometry of depositional systems, a common procedure is to make use of information from geological research, drilling, and exploitation boreholes. However, these methods are expensive and time consuming, preventing their use on a large scale. In contrast, geophysical measurements can provide a less expensive way to improve the knowledge of a set of boreholes (Maillet et al. 2005). For this reason, in many cases, geophysical prospecting techni- ques can provide complementary data that enable geological correlation, even in sectors where there are no data from boreholes. Indirect geophysical methods (like electrical resistivity tomography (ERT) and VES surveys) generate continuous data throughout a given profile. It is helps in understanding spatial relations between fresh, brackish, and saline water, which commonly coexist in coastal aquifers.

Answer 2

$<I>$Two advantages associated with water harvesting at community level are:
(a) Overexploitation of water resources will be reduced.
(b) Helps to recharge the natural wells and provides moisture for vegetation over a wide area.