GIS Analysis of Water Quality Data from Shigar Town, District Skardu, Baltistan, Pakistan

Abstract

Water quality is a major factor that influences the human health and environment of an area. Northern areas of Pakistan, especially Shigar town, which is located 30 km north-east of Skardu, suffers water quality issues. This study investigates the quality of water in Shigar town with respect to its physical, chemical and microbiological parameters. Surface water in Shigar town is used for agricultural and domestic purposes. There are three categories of water distribution system in Shigar town: (a) water supply system (b) conventional water channels and (c) water pits, commonly used in winter season. The source of water supply system is assumed to be naturally free from contaminations but it gets contaminated as a result of human activities within the inhabited area. The factors that degrade the quality of water in Shigar town are (a) lack of proper sanitation system, (b) poor maintenance of water supply network and (c) surface runoff due to rain. After preliminarily analysis, all chemical and physical parameters of water quality were within the permissible limits of WHO (World Health Organization) drinking water standards. However bacteriological parameters, such as total coliforms and thermotolerant faecel coliforms, exceed the permissible limit set by WHO. Selected medical data of Shigar health center showed that about 35% of all patients suffer from gastroenteritis. The thermotolerant faecel coliform bacteria are known to cause gastroenteritis in human beings. The water quality trends in terms of microbiological parameters were analyzed on seasonally basis using spatial datasets and GIS techniques. Further, the number of victims and sources that contribute to the contamination in water distribution systems were analyzed. It was observed that the microbiological contaminations in water supply system were least severe as compared to the microbiological contaminations in water channels and water pits. Water pits were found to be at the highest risk of bacterial contaminations. The water channels within the settlements were

more contaminated as compared to the agricultural and open land. Water quality in Shigar town was outlined through GIS analysis into no risk zone, low risk zone, intermediate risk zone, high risk zone and very high risk zone. In terms of water supply network, the areas closer to the source of water supply system had fewer contaminations as compared to the areas away from the source. It was also observed that the entire study area lies in very high risk contamination zone of water quality in terms of water pits.