Chemical quality assessment of Shiraz plain's groundwater as a drinking water resource using Geographical Information System (GIS)

Groundwater is the main source of drinking water in Shiraz city. The objective of this study was to investigation of Shiraz city groundwater’s quality, evaluation of spatial distribution of groundwater quality indexes and provision of groundwater quality maps in the selected area. In this study, 110 samples from 55 wells in the rainy and dry seasons were taken and analyzed. The water quality indexes consisted of pH, total dissolved solids (TDS), chloride, sulfate, sodium, hardness, and nitrate were measured based on the standard methods for the examination of water and wastewater book. Arcview GIS 9.3 software and an interpolation technique were used for determining the water quality maps of this area. Result showed that pH values of groundwater were at pleasure range and variable in 7 to 8.5. Sulfate concentration in the most of wells was justified in desirable limits. According to the zoning maps of groundwater, hardness was very high in all of parts of the Shiraz plain. Also, the highest nitrate concentration observed in the southeast and central of this plain. Final qualitative map of groundwater indicated that the quality of this water was decreased from east to west of this plain. The quality of groundwater in this area were classified, 4.6% in desirable level, 7.9% in suitable level, 27.7% in medium level, 48.4% in medium to poor level and 11.3% (which was located at southwest of the plain) in lowest level.