ESTIMATION OF GROUNDWATER DRAFT AND RECHARGE IN COASTAL AQUIFERS USING FIELD DATA

A simple methodology is proposed for estimation of draft and recharge for coastal alluvial aquifers using field data commonly available. For planning groundwater development on a regional basis, a reasonable estimate of discharge (draft) and rainfall recharge along space time is a prerequisite. Traditionally groundwater development has been based on lumped water balance approach. However, this approach ignores the distributed character of groundwater regime. Groundwater modelling overcomes this problem but is demanding in terms of data requirements, Further a key input for modelling i.e. groundwater extraction data (or draft) in space and time is seldom available and is often estimated using well inventory and empirical constants. Therefore, a water balance model is linked to a groundwater flow model using a unit draft concept to develop groundwater draft/recharge maps. These maps should be useful for planning groundwater development.