TR-140 : Current status of methodology for ground water assessment in the country in different region

Abstract

Ground water potential can be classified as static and dynamic. The static ground water potential can be defined as the amount of ground water available in the permeable portion of the the aquifer below the zone of water level fluctuation. The dynamic resource can be defined as the amount of ground water available in the zone of water level fluctuation. The usable ground water resource is essentially a dynamic resource which is recharged annually or periodically by rainfall, irrigation return flows, canal seepage, and influent seepage etc.

The groundwater resources need to be evaluated using groundwater balance equation containing all recharge and discharge components including the sub basin inflow and outflow. The static storage in a ground water basin should be assessed in order to use part of it during drought period. Ground water from the static storage should be used after evaluating its economic value.

The ground water estimation methodology recommended by the Ground Water Estimation Committee is being currently used in different regions of the country. The component of water balance which need further research are:(i) recharge due to rainfall and irrigation return flow in hard rock region, (ii ) recharge from tanks, (iii ) evaportranspiration losses from shallow water table (iv) influent and effluent seepage, (v) seepage from canals in hard rock region and (vi ) computation of seepage from canals in shallow water table aquifer. The dynamic nature of ground water needs to be considered while evaluating the ground water potential.