Long term groundwater balance and water quality monitoring in the eastern plains of Urmia Lake, Iran: A novel GIS based low cost approach

Groundwater quality and quantity are two major challenges in arid and semi-arid regions, due to their critical roles in sustainable agricultural development. Irrigated lands are spread all over Urmia Lake's surrounding plains in Iran. Due to the risk of saltwater intrusion as a result of over-exploitation from groundwater resources, it is important to monitor the groundwater quality and quantity through time and space. In this paper, the groundwater quantity was assessed over 11 years applying a novel groundwater balance estimation method based on water table data and 3D modeling; groundwater quality were monitored over 10 years using GIS and geostatistics; and the saltwater intrusion were investigated through generated quality maps and regression analysis. Results indicate that the groundwater balance was negative during the study period. Furthermore, the aquifers quality decreased over the study period, which was severe in west and southwest of the study area. The saltwater intrusion was proved and salty water was spread from west to other zones. The saltwater intrusion into aquifers increased electrical conductivity, chloride and sodium concentrations and will cause many ecological and agricultural problems. The novel and practicable approach utilized for groundwater balance quantitative assessment is suitable for countries lacking hydrological properties databases.