DATA & METHODS

The requisite data required for the study such as soil flow properties, groundwater abstraction, rainfall, geological formation, and observation wells was obtained from concerned Government Departments & Agencies. The initial groundwater heads were taken from 32 boreholes drilled in 2011 by the ‘Punjab Mines & Mineral Department’ for mining purposes. These boreholes also provide information regarding subsurface geology of the soil layers. The formations exposed near Katas and its vicinity indicate the presence of alluvium clay mixed with sand gravel having a thickness of 05 m from the top surface. The sand/gravel exists from 05 to 100 m and beyond 100 m shale is encountered. The rainfall data for the last 10 years (2010-2020) was used for model development. One hundred forty-nine agriculture tube wells abstracting 59,174 m3/day, 15 domestic water supply schemes abstracting 6,242 m3/day, and 27 industrial tube wells abstracting 10,284 m3/day are operational in the study area.

Groundwater Flow Model Development

Across the globe, there are many groundwater simulation platforms/ flow models such as AQUA3D, FLOWPATH, GFLOW, GMS, PROCESSING MODFLOW (PMWIN), SEAWAT, MODPATH, etc., but MODFLOW is the most commonly used three-dimensional numerical groundwater flow model developed originally by USGS (McDonald & Harbaugh, 1988). MODFLOW is based on partial differential finite difference schemes that simulate three-dimensional groundwater flow for the solution of the governing mathematical flow equations (Harbaugh, Banta, Hill, & McDonald, 2000). It has more advantages like facilities for easy data input, compatibility with other software, availability of source code, output visualization in two & three-dimensions, worldwide experience, and relatively low price (Kumar, 2002). The finite difference-based MODFLOW uses a three-dimensional flow equation (Equation 1) combining with Darcy’s Law and the principle of conservation of mass (Kumar, 2013).