ESTIMATION OF GROUNDWATER RECHARGE IN NATIONAL CAPITAL TERRITORY, DELHI USING GROUNDWATER MODELING

Abstract

Groundwater utilization in NCT of Delhi has been resorted to exploitation rapidly in the wake of increasing urbanization and production of agricultural commodities. It is, therefore, necessary to evaluate the existing trend and availability of groundwater in time and space and its movement for proper planning in near future. In the present study, an attempt has been made to carry out `groundwater flow modeling in NCT OF Delhi using finite difference technique with the help of Visual MODFLOW 4.3software. Modeling is an attempt to replicate the behavior of natural groundwater system by defining the essential features of the system in some controlled physical or mathematical manner. Visual MODFLOW is a computer program based on United States Geological Survey (USGS) MODLOW code with pre and post processor. It simulates three-dimensional groundwater flow through a porous medium by using a finite difference method. Groundwater flow within the aquifer is simulated using a block-centered finite-difference approach. For simulating the hydraulic head from a multi layered aquifer system the analysis was performed to know the impact of different flow properties on hydraulic head in groundwater model of NCT of Delhi. The boundaries, drainage networks and topography maps have been generated using Geographic Information System (GIS).Land use/cover map was derived for the study area from satellite imageries.GIS software was also used for digitizing the model boundary, district boundaries and well locations. Regional grcundw=pater flow simulations model are made using the three-dimensional numerical model MODFLOW. The groundwater flow model for the study area was formulated by using input hydrogeological data and appropriate boundary conditions. Hydraulic conductivity for the different layers and different zones has been calibrated under steady state with a constant recharge and storage (specific yield) under transient state condition on Recession stage, pre-monsoon period, peak monsoon and post-monsoon basis for simulating the hydraulic head from a multi layered aquifer system, while all other hydrogeological conditions are assumed as present conditions. The outcome of modeling shows that this model can be used for prediction purpose for the future years by updating input boundary conditions and hydrologic stresses during the preceding year. The model can be further improved if more spatial and temporal input iii parameters are available and can be incorporated into the model for more realistic characterization of groundwater flow. Keywords : groundwater; modeling; NCT of Delhi; finite difference; Visual'MODFLOW; prediction; boundary conditions. iv