Ramin Sarikhani, Amin Jamshidi, Artimes Ghasemi Dehnavi ,
Volume 14, Issue 5 (12-2020)
Abstract
Groundwater salinization in semiarid regions is a limiting factor of use with strategic importance. In this study, the sources of salinity, chemistry, and quality of groundwater in Robat (Khorramabad plain, Iran) were identified through the geochemical methods. Using data analysis, the concentration of cations and anions were recognized with the order of Ca2+>Na+ >Mg2+>K+ and HCO3-> Cl-> SO42+> NO3-> F-, respectively. The high concentration of Na+, Cl-, and EC in some places is attributed to the gypsum and salty formations. In the study area, the salinization processes are identified by natural and artificial activities. The salinization mechanisms are identified by the natural dissolution of gypsum and salt from Gachsaran formation and man-made sources including boreholes drilled through Gachsaran Formation, salt mining, and agricultural activity. Also, the high concentration of nitrate is related to agricultural fertilizers and karstification effects. It is seen that the atmospheric NO3-. HCO3-, Ca2+, and Mg2+ concentration exceeded the standard limit in a few samples probably due to the calcareous formation. Besides, hydrochemical facies of the groundwater are Ca- HCO3 and Na-K-HCO3. Due to the presence of calcareous and salt bearing formations, 46%, 26%, and 20% of all samples show a higher concentration of Ca2+, Na+, and Mg2+, respectively, which exceed the permissible limits. Sulfate and fluoride concentrations are less than the permissible limits. However, due to the presence of calcareous formation, salt bearing formation, and use of agricultural fertilizers, 100%, 26%, and 20% of all samples show a higher concentration of HCO3-, Cl-, and NO3- than the permissible limits.
Hossein Ebrahimi, Farzad Akbari, Soroor Mazrae Asl, Babak Biglari,
Volume 17, Issue 4 (12-2023)
Abstract
The Vorskharan karst spring with a catchment area of 50 square kilometers and an average discharge of about 1.35 m2/s is one of the most important springs in the city of Firouzkouh. In order to asses the hydrogeological and hydrogeochemical charachteristics of the spring, the physical and chemical properties of the spring water were measured and analyzed for several months. The results showed that the recession curve of the spring has a slope and the value of its coefficient is about 0.003. The low coefficienof the discharge variation t, electrical conductivity and major ions, as well as the single slope of the spring’s recession curve , are mainly due to the elongated shape of the aquifer and the long-term presence of snow in the catchment basin of the spring. Considering the relatively high water level of the spring and the existence of a sinkhole and a polje in the spring’s catchment area, as well as the coefficient of small changes in the physical and chemical parameters of the spring, it can be said that the dominant flow system in the aquifer which recharges Vorskharan spring,is conduit-diffusive. According to the field studies and the evaluation of the percentage of soil cover, the development of dissolved spaces and other morphological effects of karst, the percentage of annual recharge in the catchment area was estimated at 56%. With the amount of precipitation, the percentage of annual recharge, the annual recharge volume of the preliminary water catchment basin equal to 19.2 MCM and the annual discharge volume of the spring through the annual hydrograph of the spring was calculated to be equal to 20.1 MCM. It was also observed that the type of water is Ca-HCO3, and the lithology of the aquifer is calcareous and dolomite.
