Assessing the change of groundwater quality compared with land-use change and precipitation rate (Zrebar Lake's Basin)

Population, salinity, and increasing water consumption have caused high pressure on groundwater resources in Iran. The study reported here investigates the change of groundwater quality in Zrebar lake basin and the relationship between it with land-use change and precipitation rate from 1992 to 2018. To achieve the intended goal, chemical parameters of water from wells around the lake, bicarbonate (HCO³⁻), sulfate (SO₄), sodium absorption ratio (SAR), and electrical conductivity (EC) were analyzed. Then, four methods including interpolation in the ArcGIS environment, Wilcox and Schoeller Diagram in Aq.QA software and Ground Water Quality Index (GWQI) were used to indicate the trend of water quality from 1992 to 2018. To detect land-use changes from 1992 to 2018, three Landsat satellite images covering the study area were used to identify land uses and their changes during the period that shows a significant area of forests that has been replaced by agricultural use, the dominant cover in 2018, while the area of forest has declined sharply. In this study, the precipitation patterns over the past years were showed to assess the relationship between rainy and low rainfall years with water quality. The results showed that forest area in 1992, 2003 and 2018 was 70.6, 62.5 and 50.2 hectares, respectively, which shows a significant reduction, 22%, during this study period. On the other hand, the area of farmlands and human-made constructions has increased by 20% and 200%, respectively. This study additionally revealed that although there was a decreasing trend in the rate of rainfall and the agricultural lands have increased, the quality of water was still suitable for drinking and agriculture consumptions. Changes in groundwater quality were not justifiable by rainfall rate and land-use change because there was no significant relationship between them with all the groundwater quality parameters.