Quantifying changes in groundwater level and chemistry in Shahrood, northeastern Iran

• Published in: Hydrogeology journal Vol. 22; no. 2; pp. 469 - 480
• Main Authors: Ajdary, Khalil, Kazemi, Gholam A.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.03.2014; Springer Nature B.V
• Subjects: Alluvial aquifers; Aquatic Pollution; Aquifer management; Aquifers; Boreholes; Earth and Environmental Science; Earth Sciences; Geology; Geophysics/Geodesy; Groundwater; Groundwater data; Groundwater flow; Groundwater levels; Hydrogeology; Hydrology; Hydrology/Water Resources; Overexploitation; Rainfall; Reduction; Salinity; Sustainability management; Trends; Waste Water Technology; Water Management; Water Pollution Control; Water quality; Water Quality/Water Pollution; Water resources; Water resources management; Iran; Salinization; Iran; Water level decline; Temporal changes; Over-abstraction
• ISSN: 1431-2174; 1435-0157
• DOI: 10.1007/s10040-013-1042-8

Temporal changes in the quantity and chemical status of groundwater resources must be accurately quantified to aid sustainable management of aquifers. Monitoring data show that the groundwater level in Shahrood alluvial aquifer, northeastern Iran, continuously declined from 1993 to 2009, falling 11.4 m in 16 years. This constitutes a loss of 216 million m 3 from the aquifer’s stored groundwater reserve. Overexploitation and reduction in rainfall intensified the declining trend. In contrast, the reduced abstraction rate, the result of reduced borehole productivity (related to the reduction in saturated-zone thickness over time), slowed down the declining trend. Groundwater salinity varied substantially showing a minor rising trend. For the same 16-year period, increases were recorded in the order of 24% for electrical conductivity, 12.4% for major ions, and 9.9% for pH. This research shows that the groundwater-level declining trend was not interrupted by fluctuation in rainfall and it does not necessarily lead to water-quality deterioration. Water-level drop is greater near the aquifer’s recharging boundary, while greater rates of salinity rise occur around the end of groundwater flow lines. Also, fresher groundwater experiences a greater rate of salinity increase. These findings are of significance for predicting the groundwater level and salinity of exhausted aquifers.