Assessing the Impact of Human Activities and Climate Change Effects on Groundwater Quantity and Quality: A Case Study of the Western Varamin Plain, Iran

Abstract

In this paper, the effects of climate change and human activities on the groundwater level and the concentration of pollutants, such as total dissolved solids (TDS), chloride, and sodium, were investigated in the western part of the Varamin Plain. The groundwater flow and pollutant transport were simulated with the two models of MODFLOW and MT3D, respectively. To investigate the impacts of climate change, the two parameters of temperature and precipitation were downscaled under the three scenarios of RCP 2.6, RCP 4.5, and RCP 8.5. Four scenarios, including the current condition (Scenario 0), a 25% increase in the extraction from pumping wells (Scenario 1), the climate change effects (Scenario 2), and an increase in the incoming effluent (TDS) to the Shoor River due to industrial activities (Scenario 3), were investigated for a future period of 30 years (2025–2055). The results show that the highest groundwater decline and chloride and sodium concentrations occur under Scenario 1, while Scenario 3 leads to the maximum TDS concentration (milligrams per liter). In Scenario 1, the average and maximum groundwater decline at the end of the simulation period will be 2.5 m and 7.3 m, and the chloride and sodium concentrations will increase by 7 and 5 milligrams per liter, respectively.