Quality, GIS mapping and economic valuation of groundwater along river Ravi, Lahore, Pakistan

Abstract

The demand for water escalated over the years and led to water shortage in many parts of the world. This situation further intensified due to water pollution. This research involves the analysis of groundwater from selected locations along River Ravi, the estimation of economic value of water for intended uses and mapping of threat zones regarding poor quality groundwater consumed by the people or the residents of the selected areas. Questionnaire survey was used as a tool for economic valuation and laboratory analysis was performed for quality testing. The quality of water was found to be average in terms of chemical and bacteriological parameters. Whereas physical parameters were found within acceptable limits. Total dissolved solids (TDS), Turbidity and Electrical conductivity (EC) results were found to be within the permissible limits given by World Health Organization (WHO). However, pH of the water samples of few areas violated the permissible limit of WHO (6.5–8.5). Among chemical parameters, nickle (0.07 mg/l) chromium (1.0 mg/l), cobalt (0.02 mg/l) and arsenic (10 ppb) exceeded their respective permissible limit. Contingent valuation method (CVM) was used for determining Willingness to pay (WTP) for drinking water quality which was found to be low (Rs. 3.848). This was due to the low-literacy level as residents were not aware of the consequences of the contaminated water. The economic value of water for irrigation purpose determined through Residual valuation method (RVM), was found to be 37.46 Wheat > 28.41 Sugarcane > 23.05 Rice. This implicates that wheat has the highest ratio for productivity and residual value as compared to rice and sugarcane. Farmers should be encouraged to grow more of wheat crops as compared to sugarcane and rice. Threat areas for deteriorated water quality were mapped for better understanding of general public regarding drinking water quality in their vicinity.