Qualitative study of groundwater resources in the Hassanabad-Dehchah, Northeast of Neyriz, Fars province

Hydrochemistry and quality of the groundwater resources in the Hassanabad-Dehchahe plain were studied. According to the hydrograph of plain, water table was decreased about five meters during the statistical period of 13 years (2005-2017) and groundwater flow direction was from the west toward the northeast and the east. The iso-EC map showed a degradation of the water quality in the north and northwest of the study area while the groundwater quality was fairly good in the south of the region. According to the Schoeller diagram, except in one well, other groundwater samples were acceptable for drinking in the study area. Also, Wilcox diagram showed, most of the samples had fair quality for irrigation used. The mineral saturation indices shown, most of the groundwater samples were undersaturated with respect to anhydrite, gypsum and halite, and the groundwater tends to dissolve these three minerals and this affects on the groundwater chemistry. Ions ratio showed concentration of Ca and Mg is higher than bicarbonate while increasing sulfate can be due to the dissolution of sulfate minerals and reduction of Ca was due to direct cation exchange, dolomitization and or deposition of calcite. Highest salinity in the groundwater of study area were found in the dug wells. This resulted from evaporation effect on irrigation water and groundwater that confirmed by stable isotopes 2H and 18O approach. Increasing of the salinity in the groundwater had a good correlation with decreasing in the water table in the study area. Water table decreased due to low precipitation and over exploitation of the groundwater. Therefore, low rainfall, higher residence time of groundwater in the depths were caused the EC of discharged groundwater increased during time. Finally, research shows that a brackish water intrusion is happing into the freshwater aquifer as a result of high groundwater extraction.