Zoning the Groundwater Chemical Quality Attributes of Fasa Plain Using Geostatistical Approaches

Management and chemical quality of groundwater is very important in arid regions. Fasa plain (in Fars province) is an arid-semi arid region in Iran, that almost all of its residents are using groundwater in agricultural activities. Recent water shortages resulted in deepens water table, salinization and reduced groundwater quality in this area. Studying the spatial variability and zoning of the chemical quality attributes of water in order to optimum utilization and management of soil and water resources is one of the practical methods in conservation of these resources. Therefore, the spatial variability for some of groundwater quality attributes in 80 wells located in Fasa plain of Fars province including total hardness, total dissolved solids, electrical conductivity, pH, soluble cations (calcium, magnesium, sodium, and potassium) and anions (sulfate, chloride, and bicarbonate) concentration was studied and attributes were estimated by applying geostatistical methods. The suitable estimation method was determined and zoning of the studied area was done for each studied attributes. The spatial variability structure of studied attributes followed the spherical and exponential models having the range parameters of 6700 to 140600 m belonging to the moderate to strong spatial correlation classes. The Ordinary Point Kriging was determined as the suitable estimating method that used for preparing the maps of water quality zoning. The quality of groundwaters in the southern half of the studied area was lower than that of the northern half, therefore, the more sensitive management in utilization of water resources and in using of agricultural systems is needed in order to avoiding the deterioration of water quality and worsening of groundwater status that is directly related to the residents livelihood.