Estuarine Processes Geomorphic Change Active
Simulation results for geomorphic change in Suisun Bay, CA
Changes to the geomorphic structure of estuaries impact hydrodynamics, ecosystem function, and navigation. We are implementing new methods of observing and modeling these changes using innovative field and computational approaches.
Detecting changes to estuarine geomorphology is challenging due to multiple timescales of forcing and the complexity of estuarine sediment transport. Traditional vessel-based bathymetric mapping is difficult due to shallow depths, while airborne LiDAR can be hampered by low water clarity. Over decadal timescales, repeat surveys using these methods can resolve bathymetric changes. Over shorter event timescales, different methods are necessary, including bed-mounted altimeters, erosion pins, and high-resolution hydrodynamic measurements. While these methods can be spatially limited, they can resolve the centimeter-scale changes that occur in estuaries over tidal-to-annual timescales.
Modeling estuarine geomorphology is fraught with uncertainty due to unknown initial conditions and model limitations. However, applying models under various forcing scenarios can elucidate geomorphic processes and yield clues to the long-term geomorphic trajectory of estuarine features. We are using realistic and idealized model configurations to understand the mechanisms that control geomorphology under past, present, and future conditions.
Below are publications associated with this project.
Physical response of a back-barrier estuary to a post-tropical cyclone
Quantification of storm-induced bathymetric change in a back-barrier estuary
Evolution of mid-Atlantic coastal and back-barrier estuary environments in response to a hurricane: Implications for barrier-estuary connectivity
Discontinuous hindcast simulations of estuarine bathymetric change: A case study from Suisun Bay, California
Decadal-timescale estuarine geomorphic change under future scenarios of climate and sediment supply
Calibration of an estuarine sediment transport model to sediment fluxes as an intermediate step for simulation of geomorphic evolution
Temporal downscaling of decadal sediment load estimates to a daily interval for use in hindcast simulations
Annual sediment flux estimates in a tidal strait using surrogate measurements
Tidal oscillation of sediment between a river and a bay: A conceptual model
- Overview
Changes to the geomorphic structure of estuaries impact hydrodynamics, ecosystem function, and navigation. We are implementing new methods of observing and modeling these changes using innovative field and computational approaches.
Detecting changes to estuarine geomorphology is challenging due to multiple timescales of forcing and the complexity of estuarine sediment transport. Traditional vessel-based bathymetric mapping is difficult due to shallow depths, while airborne LiDAR can be hampered by low water clarity. Over decadal timescales, repeat surveys using these methods can resolve bathymetric changes. Over shorter event timescales, different methods are necessary, including bed-mounted altimeters, erosion pins, and high-resolution hydrodynamic measurements. While these methods can be spatially limited, they can resolve the centimeter-scale changes that occur in estuaries over tidal-to-annual timescales.
Modeling estuarine geomorphology is fraught with uncertainty due to unknown initial conditions and model limitations. However, applying models under various forcing scenarios can elucidate geomorphic processes and yield clues to the long-term geomorphic trajectory of estuarine features. We are using realistic and idealized model configurations to understand the mechanisms that control geomorphology under past, present, and future conditions.
- Publications
Below are publications associated with this project.
Physical response of a back-barrier estuary to a post-tropical cyclone
This paper presents a modeling investigation of the hydrodynamic and sediment transport response of Chincoteague Bay (VA/MD, USA) to Hurricane Sandy using the Coupled Ocean-Atmosphere-Wave-Sediment-Transport (COAWST) modeling system. Several simulation scenarios with different combinations of remote and local forces were conducted to identify the dominant physical processes. While 80% of the waterAuthorsAlexis Beudin, Neil Kamal Ganju, Zafer Defne, Alfredo AretxabaletaQuantification of storm-induced bathymetric change in a back-barrier estuary
Geomorphology is a fundamental control on ecological and economic function of estuaries. However, relative to open coasts, there has been little quantification of storm-induced bathymetric change in back-barrier estuaries. Vessel-based and airborne bathymetric mapping can cover large areas quickly, but change detection is difficult because measurement errors can be larger than the actual changes oAuthorsNeil K. Ganju, Steven E. Suttles, Alexis Beudin, Daniel J. Nowacki, Jennifer L. Miselis, Brian D. AndrewsEvolution of mid-Atlantic coastal and back-barrier estuary environments in response to a hurricane: Implications for barrier-estuary connectivity
Assessments of coupled barrier island-estuary storm response are rare. Hurricane Sandy made landfall during an investigation in Barnegat Bay-Little Egg Harbor estuary that included water quality monitoring, geomorphologic characterization, and numerical modeling; this provided an opportunity to characterize the storm response of the barrier island-estuary system. Barrier island morphologic responsAuthorsJennifer L. Miselis, Brian D. Andrews, Robert S. Nicholson, Zafer Defne, Neil K. Ganju, Anthony S. NavoyDiscontinuous hindcast simulations of estuarine bathymetric change: A case study from Suisun Bay, California
Simulations of estuarine bathymetric change over decadal timescales require methods for idealization and reduction of forcing data and boundary conditions. Continuous simulations are hampered by computational and data limitations and results are rarely evaluated with observed bathymetric change data. Bathymetric change data for Suisun Bay, California span the 1867–1990 period with five bathymetricAuthorsNeil K. Ganju, Bruce E. Jaffe, David H. SchoellhamerDecadal-timescale estuarine geomorphic change under future scenarios of climate and sediment supply
Future estuarine geomorphic change, in response to climate change, sea-level rise, and watershed sediment supply, may govern ecological function, navigation, and water quality. We estimated geomorphic changes in Suisun Bay, CA, under four scenarios using a tidal-timescale hydrodynamic/sediment transport model. Computational expense and data needs were reduced using the morphological hydrograph conAuthorsN. K. Ganju, D. H. SchoellhamerCalibration of an estuarine sediment transport model to sediment fluxes as an intermediate step for simulation of geomorphic evolution
Modeling geomorphic evolution in estuaries is necessary to model the fate of legacy contaminants in the bed sediment and the effect of climate change, watershed alterations, sea level rise, construction projects, and restoration efforts. Coupled hydrodynamic and sediment transport models used for this purpose typically are calibrated to water level, currents, and/or suspended-sediment concentratioAuthorsN. K. Ganju, D. H. SchoellhamerTemporal downscaling of decadal sediment load estimates to a daily interval for use in hindcast simulations
In this study we used hydrologic proxies to develop a daily sediment load time-series, which agrees with decadal sediment load estimates, when integrated. Hindcast simulations of bathymetric change in estuaries require daily sediment loads from major tributary rivers, to capture the episodic delivery of sediment during multi-day freshwater flow pulses. Two independent decadal sediment load estimatAuthorsN. K. Ganju, N. Knowles, D. H. SchoellhamerAnnual sediment flux estimates in a tidal strait using surrogate measurements
Annual suspended-sediment flux estimates through Carquinez Strait (the seaward boundary of Suisun Bay, California) are provided based on surrogate measurements for advective, dispersive, and Stokes drift flux. The surrogates are landward watershed discharge, suspended-sediment concentration at one location in the Strait, and the longitudinal salinity gradient. The first two surrogates substitute fAuthorsN. K. Ganju, D. H. SchoellhamerTidal oscillation of sediment between a river and a bay: A conceptual model
A conceptual model of fine sediment transport between a river and a bay is proposed, based on observations at two rivers feeding the same bay. The conceptual model consists of river, transitional, and bay regimes. Within the transitional regime, resuspension, advection, and deposition create a mass of sediment that oscillates landward and seaward. While suspended, this sediment mass forms an estuaAuthorsN. K. Ganju, D. H. Schoellhamer, J.C. Warner, M.F. Barad, S.G. Schladow