analyzing the temporal variation of groundwater level in Attanagalu oya basin using numerical models

Abstract

Scarcity for drinking water becomes one of the enormous threats around the world due to the increase in population, climatic fluctuation and pollution. Sri Lanka is considered as a country with little or no water scarcity when reckoning the whole country as one unit. However, several local regions have been identified with temporal water scarcity. Attanagalu Oya basin which covers almost the entire Gampaha district is a major hydrologic feature in determining the groundwater characteristics of the region. In this study, the temporal groundwater variation of the Attanagalu Oya basin was quantitatively analyzed. Using the data obtained from data loggers and field surveys, a numerical model for the groundwater in the basin was designed by using two software modelling approaches, a self-written Fortran code and Visual MODFLOW by USGS. Fortran code is mainly used for runoff modelling and Visual MODFLOW is for subsurface modelling. The quantitative variation obtained from the model was then examined temporally and spatially to correlate the upstream to downstream flow and monsoonal recharging impacts. The possible reasons for the observed deterioration and variations in the groundwater quantity can be contemplated as keys to providing recommendations for sustainable management of the groundwater resources in the basin.