Seawater intrusion is a global problem for coastal communities that rely on groundwater. Excessive groundwater pumping along coastal regions has been shown to accelerate seawater intrusion and to have the potential to render critical water sources unusable. Domestic wells in Fogland Point, Tiverton, RI have recently experienced an increase in groundwater salinity, particularly during summer months. This project examines the hydrogeology of Fogland Point through field investigation, data analysis, and groundwater modeling. FloPy, a python package interface for MODFLOW, and SWI2, the seawater intrusion package were used to investigate the relationships between groundwater withdrawals and the position of the 50% interface between freshwater and seawater.

 

The project employed the use of data transducers for the continuous measurement of water levels, temperature, and salinity, along with field and lab measurements of water quality, local weather stations for precipitation, and local tide gauges. The results from field activities show high salinity concentrations in multiple wells on Fogland Point. The model supports the field observations with the presence of the 50% freshwater-seawater interface at approximately -145 feet MSL below the peninsula. The amount of groundwater withdrawals by wells are less of a factor on salinity concentrations than the total depth of the wells and seasonal changes in groundwater recharge. Shallow wells generally produce fresher water, unless being influenced by salinity from water treatment system brine disposal or increased deep-zone mixing from hydro-fracking.

 

Find the report here.

Find the analyses here.