Geostatistical Assessment of Shallow Groundwater Risk in Urban Coastal Virginia: A Case Study from Virginia Beach

Urban groundwater assessments in coastal cities often rely on public monitoring datasets that are spatially uneven and temporally discontinuous. This study evaluates shallow groundwater risk in Virginia Beach, Virginia, using 30 years of records (1991–2020) from 121 monitoring wells for groundwater levels and 55 wells with groundwater‑quality data for chloride (Cl), iron (Fe), and manganese (Mn). The analysis is restricted to the NLCD 2024 urban land‑cover class, which provides sufficient data density for spatial modeling. Groundwater levels and a Composite Contamination Index (CCI) were analyzed within a three‑dimensional block model (50 × 50 × 5 m) using Sequential Gaussian Simulation (50 conditional realizations per variable). Simulation outputs were summarized using E‑type estimates, uncertainty metrics, and conservative percentile scenarios to characterize spatial patterns under data limitations. The results indicate that groundwater conditions suitable for new abstraction are extremely limited. More than 94 % of the urban domain is classified as not recommended, while less than 1 % exhibits moderate to favorable conditions. Shallow groundwater levels, elevated uncertainty, and groundwater‑quality stress overlap most strongly in urban–wetland transition areas south of the Green Line, previously identified as hydrogeologically sensitive. The analysis provides screening‑level support for urban groundwater management. Incorporating groundwater depth, quality, and spatial uncertainty into a unified assessment offers a practical basis for monitoring prioritization and precautionary decision‑making in Virginia Beach and in similar coastal cities that rely on public groundwater data.