Document Type : Original Article
Authors
1 School of Energy Engineering and Sustainable Resources, College of Interdisciplinary Science and Technology, University of Tehran, Tehran, Iran
2 Water Research Institute, Ministry of Energy, Tehran, Iran.
Abstract
Groundwater management in arid and semi-arid regions is crucial due to the challenges posed by water salinity. Kashan Plain, located in central Iran, is experiencing a decline in groundwater quality due to over-extraction and mixing with saline sources. This study employs hydrogeochemical methods to evaluate the theoretical mixing ratio of saline and fresh groundwater and assess the impact of saltwater intrusion on the aquifer. The novelty of this research lies in the application of GWISWI and GWISI indices for a more precise assessment of groundwater mixing processes and the first-ever calculation of the saline-freshwater mixing ratio in this region. For this study, 42 water samples were collected from wells, qanats, and the Kashan playa and analyzed using Ion Chromatography (IC) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The results indicate that the eastern and northeastern sections of the aquifer have the highest salinity levels (TDS > 212,000 mg/L), whereas the southern and western areas exhibit better water quality. Additionally, deep brine upconing was identified as the primary cause of salinity, with mixing levels reaching up to 70% in some wells. Conversely, the findings confirm that saltwater intrusion from the playa into the aquifer does not occur. These results underscore the urgent need for sustainable groundwater management, controlled extraction, and reduced exploitation of deep brine sources.
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