Investigation of groundwater level fluctuations and potable water volume of Kazeroun plain aquifer using statistical analysis, electrical conductivity and GIS

The increase in population along with the increase in water extraction from groundwater resources and decrease in rainfall has led to decrease in the water volume of aquifers in most parts of Iran. Kazeroun alluvial aquifer with an area of ​​695.082 square kilometers is one of the most important aquifers in Fars province, which provides a major part of the water demand for drinking, agriculture and industry in the area, as well as the drinking water demand by the neighboring areas. Therefore, it is very important to determine the volume of potable water of the aquifer in this area. SPI method was used to investigate changes in precipitation and its effect on groundwater resources. In this study, the changes in the groundwater level in the period of 2000-2020 were investigated with statistical and geostatistical methods. The statistical parameters of the groundwater level fluctuations with the map of iso-potential lines of groundwater and iso-Electrical Conductivity (EC) lines of the aquifer determined. The results showed that the maximum drawdown of groundwater in the region is 40.63 meters in its northern part. Hierarchical Clustering Analysis (HCA) investigation of groundwater level fluctuations in the period of 2000-2020 showed that the groundwater level fluctuations of the observation wells in the region fall into 6 main branches. A cross section was drawn along three lines in the area to determine the depth and type of bedrock. The bedrock contour line map was drawn using the bedrock information in 145 points, including the available information of the drawn cross-sections along with the checking of the drilling log of 143 exploitation wells in the area. Alluviums of the plain were classified based on geological maps, satellite images, geoelectric data, drilling logs, data from observation and piezometric wells and the nature of aquifers into 5 subgroups as: A1, A2, B1 , B2 and B3. In order to accurate the hydrodynamic parameters of the aquifer, pumping tests were done at 5 points of the area, and the weighted specific yield ​​of the aquifer were calculated using GIS. The iso-EC lines of the aquifer drawn in 2020 based on the drinking water standard of Iran Standards Institute and based on the 2014 European drinking water standard. Finally, the water volume of the aquifer was calculated based on the depth of bedrock, iso-potential lines of groundwater, lines of iso-EC of the aquifer, the boundary of the aquifer and the specific yield as 326.2 MCM, of which 91.55 MCM has drinking water with EC less than 1000 micromos/cm and 249.1 MCM  of it has drinking water with EC less than 2500 micromos/cm.