study of spatial and temporal variations of groundwater salinity in yazd province using indicator kriging geostatistical method

yazd province is one of the most arid regions of iran and its agriculture particularly pistachio cultivation depends on groundwater resources. in the recent decades, natural factors (drought and severe evaporation) and human activities (over- exploitation of groundwater) caused a sharp decline in the quality and quantity of groundwater in this province. in the present study, the spatial and temporal variations in groundwater salinity (ec) were evaluated using geostatistical methods and arcgis software. for this purpose, ordinary kriging and indicator kriging were used to prepare zoning and probabilistic maps, respectively. zoning and probabilistic maps showed an increase of groundwater salinity towards higher than 8 ds/m from 2003 to 2012. it was also found that groundwater of ardakan, bafgh, taft, and abarkouh cities has a very bad condition in terms of salinity and using it for pistachio orchards irrigation can reduce seriously the yield of this plant and its cultivation in the province will be questionable. so as to avoid lowering the quality of groundwater resources in the province, appropriate management measures such as well volumetric water gauge installation and banning both well water extraction and new well water allocation are required.