This study investigates the influence of key factors-mainly recharge rate and degradation half-life--on downward migration of the widely used pesticide mecoprop (MCPP) through a typical clayey till aquitard. The study uses the numerical model FRAC3Dvs, which is a three-dimensional discrete fracture/matrix diffusion (DFMD) numerical transport model. The model was calibrated with laboratory and f...

Ground water samples (37 to 186 m depth) from Baldwin County, Alabama, are used to define the hydrogeology of Gulf coastal aquifers and calculate the subsurface discharge of nutrients to the Gulf of Mexico. The ground water flow and nitrate flux have been determined by linking ground water concentrations to 3H/3He and 4He age dates. The middle aquifer (A2) is an active flow system characterized...

One of the important challenges in geological storage of CO2 is predicting, monitoring, and managing the risk of leakage from natural and artificial pathways such as fractures, faults, and abandoned wells. The risk of leakage arises from the buoyancy of free-phase mobile CO2 (gas or supercritical fluid). When CO2 dissolves into formation brine, or is trapped as residual phase, buoyancy forces a...

Tide-induced hydraulic head fluctuation results in significant airflow above the water table if the aquifer is air-confined, for example, if the aquifer is capped by low permeability materials. Hypothetical studies on the interaction between tidal fluctuation and airflow in coastal aquifers are carried out using an air–water two-phase numerical model. The results show that both the amplitude of...

A numerical model is developed to examine coastal groundwater processes in a sandy beach, including the effects of tidal fluctuations, saltwater intrusion into an aquifer, and dynamics in unsaturated layers. The simulation results indicate: 1) ‘Local circulation’ is clearly formed in the aquifer near the shoreline owing mainly to tidal oscillations. 2) The circulation induces a landward bending...

The main aquifer of the Llobregat delta (Barcelona, Spain) has been affected by seawater intrusion since the 1960s. The Catalan Water Agency (ACA) has sponsored the construction of a positive hydraulic barrier in order to stop the progress of seawater intrusion advance due to the intensive aquifer development. The hydraulic barrier consists of 15 wells into which highly treated reclaimed water ...

A procedure is presented for calculating the hydraulic conductivity of an aquifer near a well from the rate of rise of the water level in the well after a certain volume of water is suddenly removed. The calculation is based on the Thiem equation of steady state flow to a welL. The effective radius Re over which the head difference between the equilibrium water table in the aquifer and the wate...

The rock-hosted, oceanic crustal aquifer is one of the largest ecosystems on Earth, yet little is known about its indigenous microorganisms. Here we provide the first phylogenetic and functional description of an active microbial community residing in the cold oxic crustal aquifer. Using subseafloor observatories, we recovered crustal fluids and found that the geochemical composition is similar...

This paper reviews groundwater research studies with emphasis on modeling as a tool for management of Hawaii’s resources. Hawaii depends to a great extent on groundwater resources, and concern over availability of potable water has guided research regarding both water quantity and quality. Research is mainly aimed at understanding Hawaii hydrogeology, identifying aquifer parameters and modeling...