Influences on salinity variability and change in the Delaware Estuary

Open Access
Ross, Andrew Charles
Graduate Program:
Master of Science
Document Type:
Master Thesis
Date of Defense:
July 02, 2013
Committee Members:
  • Raymond Gabriel Najjar Jr., Thesis Advisor
  • salinity
  • streamflow
  • climate change
  • sea level
  • estuaries
  • generalized additive mixed models
In estuaries, salinity has a strong influence on both the physical properties of the estuary and the health of the estuarine ecosystem. In this work, statistical models are applied to establish the response of salinity in the Delaware Estuary to environmental and climatic influences including streamflow, sea level, and wind stress. Unlike some statistical approaches, the models used here are semi-parametric and are robust against autocorrelated and heteroscedastic errors. After using the models to adjust for the influence of streamflow and seasonal effects on salinity, several locations in the estuary show significant upwards trends in salinity. Replacing time with sea level in the models produces salinity-sea level relationships that match those predicted by dynamical models, which suggests that sea-level rise is causing increased salinity in the estuary. Alongshore wind stress also appears to play some role in driving salinity variations, consistent with the associated Ekman transport between the estuary and the ocean. Future changes in streamflow and the associated effects on salinity are uncertain. However, the results suggest that continued sea-level rise in the future will cause salinity to increase regardless of any change in streamflow.