Spatiotemporal Analysis of Available Freshwater Resources in Watersheds Across Northern New Jersey

This study conducts a spatiotemporal analysis of groundwater data to map freshwater availability in Northern New Jersey, defining "freshwater coverage" as areas with groundwater specific conductance ≤750 µS/cm. Using ambient groundwater monitoring well data, salinity levels are predicted through geostatistical modeling, with specific conductance serving as a proxy for salinity. Kriging interpolation is employed to assess spatial variations in groundwater quality, utilizing optimal semivariogram models (e.g., Gaussian, Spherical, Exponential) for log-transformed data. Model accuracy is evaluated using metrics such as mean error (ME), mean standard error (MSE), root mean square error (RMSE), and root mean square standard error (RMSSE). The analysis reveals significant spatial and temporal variations in specific conductance, highlighting declining freshwater coverage, particularly in the Northeast region, which is most impacted by anthropogenic activities compared to the Northwest and Raritan regions. Overlaying highways and major roads on interpolation surfaces demonstrates a strong correlation between groundwater quality changes, changes in land use, and the widespread use of deicing salts on road networks. The findings highlights the decline in freshwater coverage and the influence of land use changes and road salt application on groundwater quality in Northern New Jersey.