Sustainable Solutions for the Drying Up of Groundwater Wells – A Case Study in a Selected Watershed in Dampe, Sri Lanka

Abstract

Groundwater has now become a limited resource due to the adverse impacts of various natural and anthropogenic causes. Due to the increasing population and rapid urbanization, the demand for groundwater has been ever in-creasing. Consequently, the occurrence of declining groundwater tables and drying up of wells have been reported in different parts of the country. In order to identify adverse impacts and facilitate early decision making, it is necessary to assess and evaluate ungauged small watersheds with simple, easy to apply but quantitative tools. This paper demonstrates the possibility of successfully applying a conceptual, lumped parameter rainfall-runoff model based on water balance approach (The ABCD model) in combination with a basic (Single Basin) HEC-HMS model to identify a comprehensive solution for the drying up of groundwater wells, for Dampe watershed (0.62km2), Sri Lanka. The model was used to carry out a quantitative analysis of groundwater storage and identify the interaction with land use pattern, and it was developed by using gathered and simulated usage and recharge data of the surface and groundwater basins. Several scenarios have been analysed using the ABCD model, in order to identify the ground-water depletion at the present condition, in the future condition (with 50% increase in the impervious area of the catchment) and the proposed solution scenario, which is to increase the pervious area of the catchment. The developed single basin HEC-HMS model has been used in order to determine the peak flow associated with a 10-year re-turn period storm event. Remedial measures to overcome the problem and sustainable methods to preserve water for the future generation are proposed based on the findings of the study.