Effect of Drought on Temporal and Spatial Variability of Groundwater Quality in Shahrekord Plain and the Aquifer Vulnerability

One of the most important and primary solutions to prevent groundwater pollution is to investigate the vulnerability of aquifer and plain. In this study, it was investigated the effect of drought on the temporal and spatial changes of groundwater quality of Shahrekord plain and vulnerability of the aquifer. For this purpose, water quality data related to 11 wells were collected and rainfall information during 2001-2020, too. The time trend of changes in groundwater quality variables of Shahrekord plain was evaluated using Mann-Kendall test. Also, for each time series, trend line slope was obtained using SEN gradient estimator. Spatial trend and zoning maps of groundwater quality variables of Shahrekord plain were obtained using IDW method and Arc GIS software. The SPI and GRI used as drought indices. Finally, vulnerability of the aquifer was calculated using DRASTIC and SINTACS models. The results show that groundwater in Shahrekord plain has a significant temporal trend in some places and groundwater quality has decreased in some areas, especially southern parts of the aquifer. According to the zoning maps, during the statistical period the groundwater resources have been associated with a decrease in the quality. According to the drought indicators, it can be concluded that Shahrekord plain was in a wet period from 2001 to 2010 and from 2010 to 2020 has entered the period of drought. Finally, according to the DRASTIC and SINTACS models, it can be concluded that the vulnerability of Shahrekord plain is in the range of very low to moderate. Generally, it concludes that although the drought has decreased the groundwater quality of the Shahrekord but it also reduce the groundwater vulnerability and significantly decreased risk of any contamination.