Recent groundwater and lake-stage trends in Cape Cod National Seashore: relationships with sea level rise, precipitation, and air temperature

Abstract

AbstractHydrological features on Cape Cod, Massachusetts, USA, include groundwater, freshwater lakes, permanent and seasonal ponds, streams, and estuaries. Rainfall and evaporation/evapotranspiration have long been considered the dominant factors influencing both lake and groundwater levels in this sole-source, unconfined aquifer. However, increases in sea level may also have an effect, especially on this narrow peninsula with a sandy substrate of high permeability. In this study, we analyzed trends between 2000 and 2017 in eleven groundwater wells and nine kettle ponds situated with Cape Cod National Seashore (CCNS). We further explored relationships of these hydrologic variables with local precipitation, temperature and sea level during this period. The results suggest that while precipitation patterns influence seasonal and inter-annual variability, it appears that sea level rise (SLR) may be partially responsible for driving the longer-term trend of rising groundwater levels in several wells. Pond stages did not exhibit any statistically significant trends, and responded more to precipitation during this period of time. Notwithstanding, further acceleration of SLR, along with potential changes in precipitation patterns, can alter the freshwater hydrology of CCNS that may subsequently have biological, chemical, and physical effects throughout these systems.