U.S. Geological Survey simulations of 3D-hydrodynamics in Delaware Bay (2019) to improve understanding of the mechanisms driving salinity intrusion

The Coupled Ocean-Atmosphere-Wave-Sediment Transport (COAWST Warner and others, 2019; Warner and others, 2010) model was used to simulate three-dimensional hydrodynamics and waves to study salinity intrusion in the Delaware Bay estuary for 2019. Salinity intrusion in coastal systems is due in part to extreme events like drought or low-pressure storms and longer-term sea level rise, threatening economic infrastructure and ecological health. Along the eastern seaboard of the United States, approximately 13 million people rely on the water resources of the Delaware River basin, which is actively managed to suppress the salt front (or ~0.52 daily averaged psu line) through river discharge targets. However, river discharge is only part of the story. The other mechanisms controlling salinity intrusion include tidal motions on daily and spring-neap cycles, bathymetric and topographic features, and meteorological events. It is the interaction of these mechanisms that ultimately determines the distribution of salt in an estuary, particularly during periods of low discharge. The purpose of this study is to examine the mechanisms controlling the location of the salt front in the Delaware Bay estuary using a calibrated three-dimensional hydrodynamic model, the Coupled Ocean Atmosphere Wave and Sediment Transport (COAWST; v. 3.6) modeling system. The model was forced with tides, subtidal water levels, bulk atmospheric conditions, and waves. Compared with the observation-based location of the salt front line the model captured the major dynamics throughout the year and performed well during times of low discharge. The daily average salt front moved almost 16 km (10 mi) within a neap-spring tidal cycle, while low pressure storm systems were found to move the daily averaged salt front by 13-16 km in one event. 
 
This is a summary page for the collection of 4 subpages.
 
-The first subpage is for the Delaware Bay simulation with only river discharge and tidal forcing.
-The second subpage is for the Delaware Bay simulation with river discharge, tidal forcing, and subtidal water levels.
-The third subpage is for the Delaware Bay simulation with river discharge, tidal forcing, subtidal water levels, and bulk atmospheric forcing.
-The fourth subpage is for the Delaware Bay simulation with river discharge, tidal forcing, subtidal water levels, bulk atmospheric forcing, and waves.
 
Reference cited:
 
Warner, J.C., Armstrong, Brandy, He, Ruoying, and Zambon, J.B., 2010, Development of a coupled ocean-atmosphere-wave-sediment transport (COAWST) modeling system: Ocean Modelling, v. 35, issue 3, p. 230-244.
 
Warner, J.C., Ganju, N.K., Sherwood, C.R., Tarandeep, K., Aretxabaleta, A., He, R., Zambon, J., and Kumar, N., 2019, Coupled-Ocean-Atmosphere-Wave-Sediment Transport (COAWST) Modeling System: U.S. Geological Survey Software Release, 23 April 2019, https://doi.org/10.5066/P9NQUAOW.