Submarine Ground Water Discharge Driven by Tidal Pumping in a Heterogeneous Aquifer

Submarine ground water discharge (SGD) is now recognized as an important water pathway between land and sea. It is difficult to quantitatively predict SGD owing to its significant spatial and temporal variability. This study focuses on quantitative estimation of SGD caused by tidally induced sea water recirculation and a terrestrial hydraulic gradient. A two-dimensional hydrogeological model was developed to simulate SGD from a coastal unconfined aquifer in the northeastern Gulf of Mexico, where previous SGD studies were performed. A density-variable numerical code, SEAWAT2000, was applied to simulate SGD. To accurately predict discharge, various influencing factors such as heterogeneity in conductivity, uncertain boundary conditions, and tidal pumping were systematically assessed. The tidally influenced sea water recirculation zone and the fresh water–salt water mixing zone under various tidal patterns, tidal ranges, and water table heights were also investigated. The model was calibrated and validated from long-term, intensive measurements at the study site. The percentage of fresh SGD relative to total SGD ranged from 4% to 50% under normal conditions. Based on simulations of two field measurements in summer and spring, respectively, the fresh water ratios were 9% and 15%, respectively. These results support the hypothesis that the SGD induced by tidally driven sea water recirculation is much larger than terrestrial fresh ground water discharge at this site. The estimates of total and fresh SGD are at the low and high ends, respectively, of the estimation ranges obtained from geochemical tracers (e.g., ²²²Rn).     

Installing Multilevel Sampling Arrays to Monitor Ground Water and Contaminant Discharge to a Surface Water Body

A simple, effective method for the installation and sampling of vertically discrete points in a dynamic beach environment was developed and tested on the eastern shore of Lake Michigan, The installation permitted the vertical resolution of a ground water plume discharging to the lake and allowed monitoring of temporal variations during relatively calm and stormy periods of the year. These installations permit the definition of vertical heterogeneities such as oxidation-reduction conditions and geochemical characteristics that are expected to impact the transport and fate of ground water contaminants discharged to the surface water.     

Hydrogeological Conditions of Submarine Groundwater Discharge in the Crimea

A structural hydrogeological model of the Crimea based on the assumption of the leading role of faults in groundwater distribution is discussed. Areas with intense submarine groundwater discharge are outlined. The existence of water streams related to the faults in the area of the Chernaya River, Mramornaya Gully, Varnautskaya Depression, Batiliman Bay, and Nikitskii Cape is substantiated. The sites for drilling hydrogeological wells are recommended.     

Water Chemical Composition of Karelian Rivers and Their Dissolved Chemical Discharge into the White Sea

Data from permanent seasonal observations are used to show changes in the chemical composition of water and the discharge of major dissolved chemicals by rivers flowing into the White Sea in years with different water abundances. The proportions of the anthropogenic component in the discharge of nitrate nitrogen and in the total of principal ions were evaluated for the Nizhniy Vyg River.