Geographic scenario of drinking water quality of Lahore metropolitan, Pakistan, in response to urbanization and water demand: A GIS perspective

This study is intended to evaluate and segregate potential zones of groundwater quality over residential area of Lahore, Pakistan, where population growth and modernization of urban infrastructure are exerting pressure on finite groundwater resources. The study is based on the groundwater quality data of the year of 2016, with physicochemical quality parameters of total dissolved solids (TDS) potential hydrogen (pH), calcium (Ca), chlorine (Cl), magnesium (Mg) and bicarbonates (HCO3). Optimal spatial interpolation methods are applied to generate continuous information of all quality parameters using geospatial techniques. Each thematic map of quality parameter has been classified using standard laid down by World Health Organization (WHO). A brief spatial analysis of given quality parameters has been made with reference to their possible source and underground movement. Then, all parameters are overlaid to generate a single indicator of water quality in form of water quality index (WQI) that has been used for segregation of groundwater quality zones. An insight analysis of the spatial pattern of WQI has shown that urban expansion in the southeastern region of study area that has been transformed from agricultural land to impervious surface is the reason behind increased concentration of contaminants in local groundwater. Other prominent zones of contaminated groundwater are found near regions of Anarkali and Gulberg.