The issue of groundwater recharge has gained importance in countries where there is not enough water supply to the aquifer. However, groundwater recharge is a difficult parameter to determine. This difficulty stems from factors such as the location of the area to be studied, time, cost, and hydrological data. Numerical, isotope, and chemical approaches are used in groundwater recharge investigations. Numerical and chemical approaches are more costly and time-consuming than chemical approaches. This study aims to ascertain alluvial aquifer recharge in Alaşehir (Manisa) sub-basin using chemical approaches (Chloride Mass Balance Method) and its applicability. For this purpose, research wells were drilled at 25 different points in the alluvial aquifer, water sampling was done in wet and dry periods, and rainwater water samples were collected. Groundwater recharge was calculated by using chemical approaches from the chloride concentrations of the water samples collected. An annual average of 74.84 mm of recharge was found in the Alaşehir sub-basin. This value corresponds to 16.38% of annual rainfall. At the same time, it was examined the groundwater and geothermal mixing mechanism to demonstrate the applicability of the Chloride Mass Balance Method. It was concluded that geothermal fluid in Alaşehir sub-basin mixed with groundwater at a rate of 17%.

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The issue of groundwater recharge has gained importance in countries where there is not enough water supply to the aquifer. However, groundwater recharge is a difficult parameter to determine. This difficulty stems from factors such as the location of the area to be studied, time, cost, and hydrological data. Numerical, isotope, and chemical approaches are used in groundwater recharge investigations. Numerical and chemical approaches are more costly and time-consuming than chemical approaches. This study aims to ascertain alluvial aquifer recharge in Alaşehir (Manisa) sub-basin using chemical approaches (Chloride Mass Balance Method) and its applicability. For this purpose, research wells were drilled at 25 different points in the alluvial aquifer, water sampling was done in wet and dry periods, and rainwater water samples were collected. Groundwater recharge was calculated by using chemical approaches from the chloride concentrations of the water samples collected. An annual average of 74.84 mm of recharge was found in the Alaşehir sub-basin. This value corresponds to 16.38% of annual rainfall. At the same time, it was examined the groundwater and geothermal mixing mechanism to demonstrate the applicability of the Chloride Mass Balance Method. It was concluded that geothermal fluid in Alaşehir sub-basin mixed with groundwater at a rate of 17%.@en

Gediz Basin, located in the western part of Turkey constituting 2% land of the country, has an important groundwater potential in the area. Alasehir sub-basin, located in the southeast of the Gediz Basin and subject to the extensive withdrawal for the irrigation, constitutes the study area. Natural recharge to the sub-basin due to precipitation is numerically investigated in this study. For this purpose, 25 research wells, whose depths range from 20 to 50 m, were drilled to observe the recharge and collect the necessary field data for the numerical model. Meteorological data were collected from 3 weather stations installed in the study area. The numerical model HYDRUS was calibrated using the field water content data. Soil characterization was done on the core samples; the aquifer characterization was performed, and the alluvial aquifer recharge due to precipitation was calculated. As a result, the computed recharge value ranges from 21.78 to 68.52 mm, with an average value of 43.09 mm. According to the numerical model, this amount of recharge corresponds to 10% of the amount of annual rainfall.@en