Defne, Z., N. K. Ganju, and A. Aretxabaleta
(2016), Estimating time-dependent
connectivity in marine systems, Geophys.
Res. Lett., 43, doi:10.1002/2015GL066888.
Neil Kamal Ganju, PhD
My research spans the multiple disciplines that converge in estuarine systems. Research projects include numerical model development, field observations of hydrodynamics and water quality, wetland and coastal vulnerability assessments, geomorphic change, and eutrophication. For more details, visit http://woodshole.er.usgs.gov/project-pages/estuaries/
Biography
I studied civil engineering at the University of Michigan (BSCE), the University of Florida (MSCE), and the University of California-Davis (Ph.D.). In 2001, I began working for the USGS at the California Water Science Center, on the San Francisco Bay Sediment Transport Project with Dr. David Schoellhamer. In 2008 I moved to the Woods Hole Coastal and Marine Science Center and began multiple projects throughout the northeast US. The Estuarine Processes, Hazards, and Ecosystems project, started in 2015, details the past and ongoing studies we are involved with.
Science and Products
Date published: August 6, 2019
Status: Active Coastal System Change at Fire Island, New York
Fire Island is a 50-km long barrier island along the south shore of Long Island, New York. The island is comprised of seventeen year-round communities; federal, state, and county parks; and supports distinct ecosystems alongside areas of economic and cultural value. In addition to providing resources to its residents, the barrier island also protects the heavily-populated mainland from storm...
Date published: May 2, 2019
Status: Active Back-barrier and Estuarine - Coastal System Change at Fire Island, New York
Regional-scale modeling forecasts how atmospheric forcing and oceanographic circulation influence estuarine circulation and water levels, sediment transport, and wetland change.
Contacts: Neil Kamal Ganju, PhD, Alfredo Aretxabaleta, PhD
Date published: February 21, 2019
Status: Active Estuarine Processes, Hazards, and Ecosystems-Study Sites
Estuaries are dynamic environments where complex interactions between the atmosphere, ocean, watershed, ecosystems, and human infrastructure take place. They serve as valuable ecological habitat and provide numerous ecosystem services and recreational opportunities. However, they are modified by physical processes such as storms and sea-level rise, while anthropogenic impacts such as nutrient...
Contacts: Neil Kamal Ganju, PhD
Attribution: Woods Hole Coastal and Marine Science Center
Date published: February 1, 2019
Status: Active Estuarine Processes, Hazards, and Ecosystems
Estuarine processes, hazards, and ecosystems describes several interdisciplinary projects that aim to quantify and understand estuarine processes through observations and numerical modeling. Both the spatial and temporal scales of these mechanisms are important, and therefore require modern instrumentation and state-of-the-art hydrodynamic models. These projects are led from the U.S....
Date published: December 28, 2018
Status: Active Hurricane Sandy Response- Linking the Delmarva Peninsula's Geologic Framework to Coastal Vulnerability
The Delmarva Peninsula is a 220-kilometer-long headland, spit, and barrier island complex that was significantly affected by Hurricane Sandy. In order to better constrain controls on coastal vulnerability and evolution, the region’s sediment sources, transport pathways and sediment sinks must be identified. This project defines the geologic framework of the Delmarva coastal system through...
Contacts: Laura Brothers, PhD, Elizabeth Pendleton
Date published: August 28, 2018
Status: Active Coastal Model Applications and Field Measurements
Numerical models are used by scientists, engineers, coastal managers, and the public to understand and predict processes in the coastal ocean. This project supports the development and application of open-source coastal models and has several objectives: 1) improve the code of numerical sediment-transport models by implementing new or improved algorithms; 2) obtain measurements of coastal...
Date published: March 5, 2018
Status: Active Estuarine Processes Eutrophication
Increased loadings of nutrients to estuaries have altered ecosystem function by encouraging growth of phytoplankton and macroalgae while inducing large swings in dissolved oxygen and threatening the sustainability of seagrass meadows. We are measuring and modeling these processes to understand the future trajectory of estuarine ecosystems.
Attribution: Woods Hole Coastal and Marine Science Center
Date published: March 5, 2018
Status: Active Estuarine Processes Tidal Wetlands
Tidal wetlands are an important geomorphic and ecological feature of the coastal zone. Our projects deal with the physical forcings that affect wetland stability over event-to-annual timescales, including wave attack, sediment supply, and sea-level rise.
Date published: March 5, 2018
Status: Active Estuarine Processes Coastal Hazards
Extreme tides and coastal storms transfer high water levels to estuaries through natural and managed entrances. The size of the transfer depends on the duration of the event and the geomorphology of the estuary. We use observational data and modeling scenarios to understand and spatially map this transfer at our study sites.
Attribution: Woods Hole Coastal and Marine Science Center
Date published: March 5, 2018
Status: Active Estuarine Processes Model Development
We are developing new routines within the COAWST model framework to represent coupled bio-physical processes in estuarine and coastal regions. These include routines for marsh vulnerability to waves, estuarine biogeochemistry, and feedbacks between aquatic vegetation and hydrodynamics.
Date published: March 31, 2020
Coastal wetlands of eastern Long Island, New York
This data release contains coastal wetland synthesis products for the geographic region of eastern Long Island, New York, including the north and south forks, Gardiners Island, and Fishers Island. Metrics for resiliency, including unvegetated to vegetated ratio (UVVR), marsh elevation, and mean tidal range, are calculated for smaller units delineated from a Digital Elevation Model.
Date published: November 26, 2019
U.S. Geological Survey hydrodynamic model simulations for Barnegat Bay, New Jersey, during Hurricane Sandy, 2012
We used the Coupled Ocean-Atmosphere-Wave-Sediment Transport (COAWST; Warner and others, 2010) model to simulate ocean circulation, waves, and sediment transport in Barnegat Bay, New Jersey, during Hurricane Sandy. The simulation period was from October 27 to November 4, 2012. We used a 2012 digital terrain model (Andrews and others, 2015) to prescribe the prestorm bathymetry.
Date published: October 15, 2019
Numerical model of Submerged Aquatic Vegetation (SAV) growth dynamics in West Falmouth Harbor
The development of Submerged Aquatic Vegetation (SAV) growth model within the Coupled Ocean-Atmosphere-Wave-Sediment Transport (COAWST) model leads to a change in SAV biomass. The SAV biomass is computed from temperature, nutrient loading and light predictions obtained from coupled hydrodynamics (temperature), bio-geochemistry (nutrients) and bio-optical (light) models.
Date published: October 15, 2019
Idealized numerical model for Submerged Aquatic Vegetation (SAV) growth dynamics
An idealized domain is setup to test the development of Submerged Aquatic Vegetation (SAV) growth model within the Coupled Ocean-Atmosphere-Wave-Sediment Transport (COAWST) model. The change in SAV biomass is computed from temperature, nutrient loading and light predictions obtained from coupled hydrodynamics (temperature), bio-geochemistry (nutrients) and bio-optical (light) models.
Date published: August 21, 2019
Coastal wetlands from Jamaica Bay to western Great South Bay, New York
This data release contains coastal wetland synthesis products for the geographic region from Jamaica Bay to western Great South Bay, located in southeastern New York State. Metrics for resiliency, including unvegetated to vegetated ratio (UVVR), marsh elevation, and mean tidal range, are calculated for smaller units delineated from a Digital Elevation Model.
Date published: May 29, 2019
Aerial imagery from unmanned aerial systems (UAS) flights and ground control points: Plum Island Estuary and Parker River NWR (PIEPR), February 27th, 2018.
Low-altitude (80 and 100 meters above ground level) digital images were taken over an area of the Plum Island Estuary and Parker River National Wildlife Refuge in Massachusetts using 3DR Solo unmanned aerial systems (UAS) on February 27, 2018. These images were collected as part of an effort to document marsh stability over time and quantify sediment movement using UAS technology.
Date published: March 12, 2019
Conceptual marsh units for Cape Cod National Seashore salt marsh complex, Massachusetts
The salt marsh complex of Cape Cod National Seashore (CACO), Massachusetts, USA and approximal wetlands were delineated to smaller, conceptual marsh units by geoprocessing of surface elevation data. Flow accumulation based on the relative elevation of each location is used to determine the ridge lines that separate each marsh unit
Date published: March 12, 2019
Unvegetated to vegetated marsh ratio in Cape Cod National Seashore salt marsh complex, Massachusetts
Unvegetated to vegetated marsh ratio (UVVR) in the Cape Cod National Seashore (CACO) salt marsh complex and approximal wetlands is computed based on conceptual marsh units defined by Defne and Ganju (2019). UVVR was calculated based on U.S. Department of Agriculture National Agriculture Imagery Program (NAIP) 1-meter resolution imagery.
Date published: March 12, 2019
Mean tidal range in marsh units of Cape Cod National Seashore salt marsh complex, Massachusetts
This dataset displays the spatial variation of mean tidal range (i.e. Mean Range of Tides, MN) in the Cape Cod National Seashore (CACO) salt marsh complex and approximal wetlands based on conceptual marsh units.MN was based on the calculated difference in height between mean high water (MHW) and mean low water (MLW) using the VDatum (v3.5) database ( http://...
Date published: March 12, 2019
Elevation of marsh units in Cape Cod National Seashore salt marsh complex, Massachusetts
Through scientific efforts initiated with the Hurricane Sandy Science Plan, the U.S. Geological Survey has been expanding national assessment of coastal change hazards and forecast products to coastal wetlands. The intent is to provide federal, state, and local managers with tools to estimate their vulnerability and ecosystem service potential
Date published: December 17, 2018
Oceanographic and Water Quality Measurements Collected in Grand Bay, Alabama/Mississippi, August 2016 – January 2017
Suspended-sediment transport is a critical element governing the geomorphology of tidal marshes and estuaries. Marshes rely both on organic material and inorganic sediment deposition to maintain their elevation relative to sea-level. Additionally, horizontal marsh extent is altered by lateral erosion and accretion.
Date published: December 16, 2018
Unvegetated to vegetated marsh ratio in Fire Island National Seashore and Central Great South Bay salt marsh complex, New York
Through scientific efforts initiated with the Hurricane Sandy Science Plan, the U.S. Geological Survey has been expanding national assessment of coastal change hazards and forecast products to coastal wetlands, including the Fire Island National Seashore and Central Great South Bay salt marshes.
Year Published: 2017
Quantification 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...
Ganju, Neil K.; Suttles, Steven E.; Beudin, Alexis; Nowacki, Daniel J. ; Miselis, Jennifer L.; Andrews, Brian D.View Citation
Ganju, N.K., Suttles, S.E., Beudin, A. et al. Estuaries and Coasts (2016). Quantification of storm-induced bathymetric change in a back-barrier estuary doi:10.1007/s12237-016-0138-5
Year Published: 2015
Quantifying the residence time and flushing characteristics of a shallow, back-barrier estuary: Application of hydrodynamic and particle tracking models
Estuarine residence time is a major driver of eutrophication and water quality. Barnegat Bay-Little Egg Harbor (BB-LEH), New Jersey, is a lagoonal back-barrier estuary that is subject to anthropogenic pressures including nutrient loading, eutrophication, and subsequent declines in water quality. A combination of hydrodynamic and particle tracking...
Defne, Zafer; Ganju, Neil K.View Citation
Defne, Z. and Ganju, N.K., 2015, Quantifying the residence time and flushing characteristics of a shallow, back-barrier estuary: application of hydrodynamic and particle tracking models. Estuaries and Coasts. DOI: 10.1007/s12237-014-9885-3.
Year Published: 2015
Sediment transport-based metrics of wetland stability
Despite the importance of sediment availability on wetland stability, vulnerability assessments seldom consider spatiotemporal variability of sediment transport. Models predict that the maximum rate of sea level rise a marsh can survive is proportional to suspended sediment concentration (SSC) and accretion. In contrast, we find that SSC and...
Ganju, Neil K.; Kirwan, Matthew L.; Dickhudt, Patrick J.; Guntenspergen, Glenn R.; Cahoon, Donald R.; Kroeger, Kevin D.View Citation
Ganju, N. K., Kroeger, K. D., Kirwan, M. L., Dickhudt, P. J., Guntenspergen, G. R., and Cahoon, D. R., 2015, Sediment transport-based metrics of wetland stability: Geophysical Research Letters, v. 42, no. 19, p. 7992-8000.
Year Published: 2014
Physical and biogeochemical controls on light attenuation in a eutrophic, back-barrier estuary
Light attenuation is a critical parameter governing the ecological function of shallow estuaries. In these systems primary production is often dominated by benthic macroalgae and seagrass; thus light penetration to the bed is of primary importance. We quantified light attenuation in three seagrass meadows in Barnegat Bay, New Jersey, a shallow...
Ganju, Neil K.; Miselis, Jennifer L.; Aretxabaleta, Alfredo L.
Year Published: 2014
Modeling future scenarios of light attenuation and potential seagrass success in a eutrophic estuary
Estuarine eutrophication has led to numerous ecological changes, including loss of seagrass beds. One potential cause of these losses is a reduction in light availability due to increased attenuation by phytoplankton. Future sea level rise will also tend to reduce light penetration and modify seagrass habitat. In the present study, we integrate a...
del Barrio, Pilar; Ganju, Neil K.; Aretxabaleta, Alfredo L.; Hayn, Melanie; García, Andrés; Howarth, Robert W.View Citation
del Barrio, P., Ganju, N.K., Aretxabaleta, A.L., Hayn, M., Garcia, A., and Howarth, R.W., 2014, Modeling Future Scenarios of Light Attenuation and Potential Seagrass Success in a Eutrophic Estuary: Estuaries and Coasts, v. 149, 13-23 p.
Year Published: 2014
Metabolism of a nitrogen-enriched coastal marine lagoon during the summertime
We measured metabolism rates in a shallow, nitrogen-enriched coastal marine ecosystem on Cape Cod (MA, USA) during seven summers using an open-water diel oxygen method. We compared two basins, one directly receiving most of the nitrogen (N) load (“Snug Harbor”) and another further removed from the N load and better flushed (“Outer Harbor”). Both...
Howarth, Robert W.; Hayn, Melanie; Marino, Roxanne M.; Ganju, Neil; Foreman, Kenneth H.; McGlathery, Karen; Giblin, Anne E.; Berg, Peter; Walker, Jeffrey D.View Citation
Metabolism of a nitrogen-enriched coastal marine lagoon during the summertime; 2014; Article; Journal; Biogeochemistry; Howarth, Robert W.; Hayn, Melanie; Marino, Roxanne M.; Ganju, Neil; Foreman, Kenneth; McGlathery, Karen; Giblin, Anne E.; Berg, Peter; Walker, Jeffrey D.
Year Published: 2014
Water level response in back-barrier bays unchanged following Hurricane Sandy
On 28–30 October 2012, Hurricane Sandy caused severe flooding along portions of the northeast coast of the United States and cut new inlets across barrier islands in New Jersey and New York. About 30% of the 20 highest daily maximum water levels observed between 2007 and 2013 in Barnegat and Great South Bay occurred in 5 months following Hurricane...
Aretxabaleta, Alfredo L.; Butman, Bradford; Ganju, Neil K.Attribution: Woods Hole Coastal and Marine Science Center, Region 1: North Atlantic-Appalachian, Hurricane Sandy
View Citation
Water level response in back-barrier bays unchanged following Hurricane Sandy; 2014; Article; Journal; Geophysical Research Letters; Aretxabaleta, Alfredo L.; Butman, Bradford; Ganju, Neil K.
Year Published: 2014
Exchange of nitrogen and phosphorus between a shallow lagoon and coastal waters
West Falmouth Harbor, a shallow lagoon on Cape Cod, has experienced a threefold increase in nitrogen load since the mid- to late 1990s due to input from a groundwater plume contaminated by a municipal wastewater treatment plant. We measured the exchange of nitrogen and phosphorus between the harbor and the coastal waters of Buzzards Bay over...
Hayn, Melanie; Howarth, Robert W.; Ganju, Neil K.; Berg, Peter; Foreman, Kenneth H.; Giblin, Anne E.; McGlathery, KarenView Citation
Hayn, M.; Howarth, R.; Marino, R.; Ganju, N.; Berg, P.; Foreman, K. H.; Giblin, A. E.; and McGlathery, K. Estuaries and Coasts, . 2014.
Year Published: 2013
Inferring tidal wetland stability from channel sediment fluxes: observations and a conceptual model
Anthropogenic and climatic forces have modified the geomorphology of tidal wetlands over a range of timescales. Changes in land use, sediment supply, river flow, storminess, and sea level alter the layout of tidal channels, intertidal flats, and marsh plains; these elements define wetland complexes. Diagnostically, measurements of net sediment...
Ganju, Neil K.; Nidzieko, Nicholas J.; Kirwan, Matthew L.View Citation
Inferring tidal wetland stability from channel sediment fluxes: observations and a conceptual model; 2013; Article; Journal; Journal of Geophysical Research: Earth Surface; Ganju, Neil K.; Nidzieko, Nicholas J.; Kirwan, Matthew L.
Year Published: 2013
Comparison of sediment supply to San Francisco Bay from watersheds draining the Bay Area and the Central Valley of California
Quantifying suspended sediment loads is important for managing the world's estuaries in the context of navigation, pollutant transport, wetland restoration, and coastal erosion. To address these needs, a comprehensive analysis was completed on sediment supply to San Francisco Bay from fluvial sources. Suspended sediment, optical backscatter,...
McKee, L.J.; Lewicki, M.; Schoellhamer, D.H.; Ganju, N.K.Attribution: , California Water Science Center, Water Resources, San Francisco Bay and Sacramento-San Joaquin Delta Estuary
View Citation
Comparison of sediment supply to San Francisco Bay from watersheds draining the Bay Area and the Central Valley of California; 2013; Article; Journal; Marine Geology; McKee, L. J.; Lewicki, M.; Schoellhamer, D. H.; Ganju, N. K.
Year Published: 2012
Tidal and groundwater fluxes to a shallow, microtidal estuary: Constraining inputs through field observations and hydrodynamic modeling
Increased nutrient loading to estuaries has led to eutrophication, degraded water quality, and ecological transformations. Quantifying nutrient loads in systems with significant groundwater input can be difficult due to the challenge of measuring groundwater fluxes. We quantified tidal and freshwater fluxes over an 8-week period at the entrance of...
Ganju, Neil K.; Hayn, Melanie; Chen, Shih-Nan; Howarth, Robert W.; Dickhudt, Patrick J.; Aretxabaleta, Alfredo L.; Marino, RoxanneView Citation
Tidal and groundwater fluxes to a shallow, microtidal estuary: Constraining inputs through field observations and hydrodynamic modeling; 2012; Article; Journal; Estuaries and Coasts; Ganju, Neil K.; Hayn, Melanie; Chen, Shih-Nan; Howarth, Robert W.; Dickhudt, Patrick J.; Aretxabaleta, Alfredo L.; Marino, Roxanne
Year Published: 2011
Methyl mercury dynamics in a tidal wetland quantified using in situ optical measurements
We assessed monomethylmercury (MeHg) dynamics in a tidal wetland over three seasons using a novel method that employs a combination of in situ optical measurements as concentration proxies. MeHg concentrations measured over a single spring tide were extended to a concentration time series using in situ optical measurements. Tidal fluxes were...
Bergamaschi, B.A.; Fleck, J.A.; Downing, B.D.; Boss, E.; Pellerin, B.; Ganju, N.K.; Schoellhamer, D.H.; Byington, A.A.; Heim, W.A.; Stephenson, M.; Fujii, R.Attribution: California Water Science Center, Water Resources, United States of America, Organic Matter Research Laboratory
View Citation
Methyl mercury dynamics in a tidal wetland quantified using in situ optical measurements; 2011; Article; Journal; Limnology and Oceanography; Bergamaschi, B. A.; Fleck, J. A.; Downing, B. D.; Boss, E.; Pellerin, B.; Ganju, N. K.; Schoellhamer, D. H.; Byington, A. A.; Heim, W. A.; Stephenson, M. ; Fujii, R.
Pre-USGS Publications
Ganju, N. K., Brush, M. J., Rashleigh, B., Aretxabaleta, A. L., del Barrio, P., Grear, J. S., ... & Vaudrey, J. M., 2015, Progress and challenges in coupled hydrodynamic-ecological estuarine modeling, Estuaries and Coasts, 1-22.
Ganju, N.K., Jaffe, B.E., and Schoellhamer, D.H., 2011, Discontinuous hindcast simulations of estuarine bathymetric change: a case study from Suisun Bay, California. Estuarine, Coastal and Shelf Science, 93, 142-150.
Ganju, N.K., and Schoellhamer, D.H., 2006, Annual sediment flux estimates in a tidal strait using surrogate measurements. Estuarine, Coastal and Shelf Science, 69, 165-178.
Ganju, N.K., Schoellhamer, D.H., and Jaffe, B.E., 2009, Hindcasting of decadal-timescale estuarine bathymetric change with a tidal-timescale model. Journal of Geophysical Research-Earth Surface, 114, F04019, doi:10.1029/2008JF001191.
Ganju, N.K., Schoellhamer, D.H., Warner, J.C., Barad, M.F., and Schladow, S.G., 2004, Tidal oscillation of sediment between a river and a bay: a conceptual model. Estuarine, Coastal and Shelf Science, 60(1), 81-90.
Ganju, N.K., and Sherwood, C.R., 2010, Effect of roughness formulation on the performance of a coupled wave, hydrodynamic, and sediment transport model. Ocean Modelling, 33, 299-313.
Gartner, J.W., and Ganju, N.K., 2007, Correcting acoustic Doppler current profiler discharge measurement bias from moving-bed conditions without global positioning during the 2004 Glen Canyon Dam controlled flood on the Colorado River. Limnology and Oceanography: Methods, 5, 156-162.
Leonardi, N., Ganju, N.K. and Fagherazzi, S., 2016. A linear relationship between wave power and erosion determines salt-marsh resilience to violent storms and hurricanes. Proceedings of the National Academy of Sciences, 113(1), pp.64-68.
Kirincich, A. R., Lentz, S. J., Farrar, J. T., and Ganju, N. K., 2013, The Spatial Structure of Tidal and Mean Circulation over the Inner Shelf South of Martha's Vineyard, Massachusetts. Journal of Physical Oceanography, 43(9).
Miselis, J.L., Andrews, B.D., Nicholson, R.S., Defne, Z., Ganju, N.K. and Navoy, A., 2015. Evolution of mid-Atlantic coastal and back-barrier estuary environments in response to a hurricane: Implications for barrier-estuary connectivity. Estuaries and Coasts, pp.1-19.
Oestreich, W. K., Ganju, N. K., Pohlman, J. W., and Suttles, S. E., 2016. Colored dissolved organic matter in shallow estuaries: relationships between carbon sources and light attenuation, Biogeosciences, 13, 583-595, doi:10.5194/bg-13-583-2016.
Rosencranz, J.A., Ganju, N.K., Ambrose, R.F., Brosnahan, S.M., Dickhudt, P.J., Guntenspergen, G.R., MacDonald, G.M., Takekawa, J.Y, and Thorne, K.M., 2015, Balanced sediment fluxes in southern California’s Mediterranean-climate zone salt marshes, Estuaries and Coasts, DOI 10.1007/s12237-015-0056-y.
Date published: August 31, 2018
Raising Awareness in the Classroom about Natural Hazards Facing U.S. Coastal Communities
USGS scientists present newly developed education outreach materials at the Smithsonian Science Education Academy for Teachers (SSEATs) held at the USGS National Headquarters in Reston, Virginia.
Date published: May 3, 1999
Focus on Estuaries and Coastal Wetlands
Estuaries and wetlands provide a critical defense against storms and sea-level rise while providing economically valuable services. How well they protect coastal communities and host diverse ecosystems is largely a function of their shape (morphology), which is controlled by factors such as sediment movement and biological feedbacks.