Hydrogeological framework and groundwater balance of a semi-arid aquifer, a case study from Iran.

Climate changing and associated factors combined with considerably increases in water demand have been accompanied by severe depletion of reservoir storage of the most groundwater supplies of Iran. Shahriar aquifer in west of Tehran is a representative aquifer of these kinds. In order to meet water demand of the area and protecting groundwater from quantity and quality deterioration, precision recognition of geology, hydrologic and hydrogeologic characteristics of the aquifer is first step. The basic objective of this study is to develop the hydrogeological framework of the groundwater system in Shariar, Iran and to estimate ground-water balance as a scientific database for future water resources delevopment programs. Based on this re-search lateral groundwater inflows, direct infiltration of rainfall, stream bed infiltration, irrigation return and surplus drinking and industrial water are the recharging factors of the aquifer. Subsurface outflows, domestic and industrial pumping wells and agricultural abstraction are the main parameters discharge the aquifer system. Water balance in the Shahriar aquifer system is in disequilibrium and a deficit of about 24.7 million cubic meters exists

A Proposed Approach towards Quantifying the Resilience of Water Systems to the Potential Climate Change in the Lali Region, Southwest Iran

Computing the resilience of water resources, especially groundwater, has hitherto presented difficulties. This study highlights the calculation of the resilience of water resources in the small-scale Lali region, southwest Iran, to potential climate change in the base (1961–1990) and future (2021–2050) time periods under two Representative Concentration Pathways, i.e., RCP4.5 and RCP8.5. The Lali region is eminently suitable for comparing the resilience of alluvial groundwater (Pali aquifer), karst groundwater (Bibitarkhoun spring and the observation wells W1, W2 and W3) and surface water (Taraz-Harkesh stream). The log-normal distribution of the mean annual groundwater level and discharge rate of the water resources was initially calculated. Subsequently, different conditions from extremely dry to extremely wet were assigned to the different years for every water system. Finally, the resilience values of the water systems were quantified as a number between zero and one, such that they can be explicitly compared. The Pali alluvial aquifer demonstrated the maximum resilience, i.e., 1, to the future climate change. The Taraz-Harkesh stream, which is fed by the alluvial aquifer and the Bibitarkhoun karst spring, which is the largest spring of the Lali region, depicted average resilience of 0.79 and 0.59, respectively. Regarding the karstic observation wells, W1 being located in the recharge zone had the lowest resilience (i.e., 0.52), W3 being located in the discharge zone had the most resilience (i.e., 1) and W2 being located between W1 and W3 had an intermediate resilience (i.e., 0.60) to future climate change

A Proposed Approach towards Quantifying the Resilience of Water Systems to the Potential Climate Change in the Lali Region, Southwest Iran

Computing the resilience of water resources, especially groundwater, has hitherto presented difficulties. This study highlights the calculation of the resilience of water resources in the small-scale Lali region, southwest Iran, to potential climate change in the base (1961–1990) and future (2021–2050) time periods under two Representative Concentration Pathways, i.e., RCP4.5 and RCP8.5. The Lali region is eminently suitable for comparing the resilience of alluvial groundwater (Pali aquifer), karst groundwater (Bibitarkhoun spring and the observation wells W1, W2 and W3) and surface water (Taraz-Harkesh stream). The log-normal distribution of the mean annual groundwater level and discharge rate of the water resources was initially calculated. Subsequently, different conditions from extremely dry to extremely wet were assigned to the different years for every water system. Finally, the resilience values of the water systems were quantified as a number between zero and one, such that they can be explicitly compared. The Pali alluvial aquifer demonstrated the maximum resilience, i.e., 1, to the future climate change. The Taraz-Harkesh stream, which is fed by the alluvial aquifer and the Bibitarkhoun karst spring, which is the largest spring of the Lali region, depicted average resilience of 0.79 and 0.59, respectively. Regarding the karstic observation wells, W1 being located in the recharge zone had the lowest resilience (i.e., 0.52), W3 being located in the discharge zone had the most resilience (i.e., 1) and W2 being located between W1 and W3 had an intermediate resilience (i.e., 0.60) to future climate change

Impacts of natural CO2 leakage on groundwater chemistry of aquifers from the Hamadan Province, Iran

The effect of natural CO2 leakage through water wells on groundwater chemistry from alluvial aquifers of Hamadan, Iran, has been investigated through analysis of water samples from 5 springs and 19 wells. The average CO2 partial pressure in gas charged groundwater has increased about 32 times with respect to background groundwater, leading to an increase in alkalinity and in the concentration of all ions, except for SO4, and to a decrease in pH and DO. Due to a high pH buffering capacity, pH of gas charged groundwater has decreased only one unit. The increase in salinity of the gas charged groundwater cannot be attributed to in situ weathering of aquifer materials because of (1) the lack of correlation between DIC vs δ13CDIC and TDS vs pH, (2) the high concentration of SiO2 and F and (3) the 87Sr/86Sr ratio in the range from 0.7085 to 0.7118. Instead, it can be attributed to saline CO2-rich waters from deep sources, which can dissolve a variety of minerals during their migration towards the surface. Although it is not clear the role of CH4 as electron donor, the association of δ18OSO4 and δ34SSO4 with SO4 concentration suggests that sulfate reduction could occur in the environment. The salinity of Mesozoic gas-rich springs, which present higher CO2 pressure and lower pH, is five times lower than that of Cenozoic ones because of the different degrees of metamorphism, which lead to an increase in grain size and slower reaction rate in Mesozoic than in Cenozoic carbonate rocks.B.D. acknowledges the financial support received from the “Iran’s Ministry of Science, Research and Technology, Iran” (Ph.D. students’ sabbatical grants), Hamadan regional water company and Geological survey of Iran. V.V. acknowledges funding from the European Research Council (ERC) under the European Union’s Horizon 2020 Research and Innovation Program through the Starting Grant GEoREST (www.georest.eu), grant agreement No. 801809. The authors thank for technical and human support provided by SGIker of UPV/EHU and European funding (ERDF and ESF).Peer reviewe