مطالعه کیفیت آب‌ زیرزمینی و عوامل مؤثر بر تغییرات آن در حوزه آبخیز مهارلو-بختگان

Groundwater is a renewable, limited and vital resource for human life, social and economic development. In recent years, due to the sharp decrease in the volume of underground water, it has been important to check their quality and protect them accordingly. The quality of groundwater changes due to changes in various conditions, including weather conditions, the duration of water retention in the aquifer, the type of geological formations, etc. This research has been done with the aim of investigating the origin and processes affecting the hydrochemical properties of groundwater in Maharlu-Bakhtegan watershed. The chemical quality information of groundwater resources including deep, semi-deep wells, springs and aqueducts of Fars province was prepared in the 15-year statistical period from the water year 2003-2004 to the water year 2018-2019. Then, using composite and Gibbs diagrams, the origin and causes of hydrochemical properties of groundwater were investigated. The Gibbs diagram showed that the process of evaporation plays the main role in the composition of ions and the change in the chemical quality of groundwater in the Maharlo-Bakhtegan basin, and the weathering of rocks plays a much lesser role in this issue. The destructive effect of human activities in the region was also confirmed according to the obtained results. The results of the combined graphs also showed that evaporation, dissolution of silicates, human activities, especially agricultural activities, and infiltration of saline water returned from agriculture are factors affecting the chemical quality of groundwater in the region.