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.
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.
Professional Experience
2010-present: Research Oceanographer, Woods Hole Coastal and Marine Science Center
2008-2010: Hydraulic Engineer, Woods Hole Coastal and Marine Science Center
2001-2008: Hydraulic Engineer, California Water Science Center
Education and Certifications
I studied civil engineering at the University of Michigan (BSCE), the University of Florida (MSCE), and the University of California-Davis (Ph.D.).
Science and Products
Coastal wetlands of Hudson Valley and New York City, New York
Coastal wetlands of north shore Long Island, New York
Slope Values Across Marsh-Forest Boundary in Chesapeake Bay Region, USA
Coastal wetlands of eastern Long Island, New York (ver. 2.0, March 2024)
Suspended-sediment concentration data from water samples collected in 2016-17 in Grand Bay, Alabama and Mississippi
U.S. Geological Survey hydrodynamic model simulations for Barnegat Bay, New Jersey, during Hurricane Sandy, 2012
Idealized numerical model for Submerged Aquatic Vegetation (SAV) growth dynamics
Numerical model of Submerged Aquatic Vegetation (SAV) growth dynamics in West Falmouth Harbor
Time-series of biogeochemical and flow data from a tidal salt-marsh creek, Sage Lot Pond, Waquoit Bay, Massachusetts, 2012-2016 (ver. 2.0, July 2023)
Aerial imagery from unmanned aerial systems (UAS) flights: Plum Island Estuary and Parker River NWR (PIEPR), February 27th, 2018
Unvegetated to vegetated marsh ratio in Cape Cod National Seashore salt marsh complex, Massachusetts
Mean tidal range in marsh units of Cape Cod National Seashore salt marsh complex, Massachusetts
Understanding tidal marsh trajectories: Evaluation of multiple indicators of marsh persistence
Simple metrics predict salt-marsh sediment fluxes
Hydrodynamic and morphologic response of a back-barrier estuary to an extratropical storm
Identifying salt marsh shorelines from remotely sensed elevation data and imagery
Spatial distribution of water level impact to back-barrier bays
Thin-layer sediment addition to an existing salt marsh to combat sea-level rise and improve endangered species habitat in California, USA
Changes in hydrodynamics and wave energy as a result of seagrass decline along the shoreline of a microtidal back-barrier estuary
Estimating connectivity of hard clam (Mercenaria mercenaria) and eastern oyster (Crassostrea virginica) larvae in Barnegat Bay
Role of tidal wetland stability in lateral fluxes of particulate organic matter and carbon
Marshes are the new beaches: Integrating sediment transport into restoration planning
Hydrologic controls of methane dynamics in karst subterranean estuaries
Salt marsh loss affects tides and sediment budget in shallow bays
Non-USGS Publications**
(2016), Estimating time-dependent
connectivity in marine systems, Geophys.
Res. Lett., 43, doi:10.1002/2015GL066888.
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
Science and Products
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Filter Total Items: 58
Coastal wetlands of Hudson Valley and New York City, New York
This data release contains coastal wetland synthesis products for the geographic region of Hudson Valley and New York City, New York. 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, providing the spatial variability of physical factors that influence wetland hCoastal wetlands of north shore Long Island, New York
This data release contains coastal wetland synthesis products for the geographic region of north shore Long Island, New York. 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, providing the spatial variability of physical factors that influence wetland health. TSlope Values Across Marsh-Forest Boundary in Chesapeake Bay Region, USA
The marsh-forest boundary in the Chesapeake Bay was determined by geoprocessing high-resolution (1 square meter) land use and land cover data sets. Perpendicular transects were cast at standard intervals (30 meters) along the boundary within a GIS by repurposing the Digital Shoreline Analysis System (DSAS) Version 5.0, an ArcGIS extension developed by the U.S. Geological Survey. Average and maximuCoastal wetlands of eastern Long Island, New York (ver. 2.0, March 2024)
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, providing the sSuspended-sediment concentration data from water samples collected in 2016-17 in Grand Bay, Alabama and Mississippi
Suspended-sediment transport is a critical element governing the geomorphology of tidal marshes and estuaries. Marsh elevation, relative to sea level, is maintained by both organic material and the deposition of inorganic sediment. Additionally, horizontal marsh extent is altered by lateral erosion and accretion. In wetlands within and near Grand Bay National Estuarine Research Reserve, parts of tU.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. Initial conditions for the salinity and temperature fields in the domain were acquired from a 7-month simulation of the saIdealized 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. In exchange,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. In exchange, the growth ofTime-series of biogeochemical and flow data from a tidal salt-marsh creek, Sage Lot Pond, Waquoit Bay, Massachusetts, 2012-2016 (ver. 2.0, July 2023)
Extended time-series sensor data were collected between 2012 and 2016 in surface water of a tidal salt-marsh creek on Cape Cod, Massachusetts. The objective of this field study was to measure water chemical characteristics and flows, as part of a study to quantify lateral fluxes of dissolved carbon species between the salt marsh and estuary. Data consist of in-situ measurements including: salinityAerial imagery from unmanned aerial systems (UAS) flights: 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. Each UAS was equUnvegetated 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. Through scientific efforts initiated with the Hurricane SandyMean tidal range in marsh units of Cape Cod National Seashore salt marsh complex, Massachusetts
Biomass production is positively correlated with mean tidal range in salt marshes along the Atlantic coast of the United States of America. Recent studies support the idea that enhanced stability of the marshes can be attributed to increased vegetative growth due to increased tidal range. This dataset displays the spatial variation of mean tidal range (i.e. Mean Range of Tides, MN) in the Cape Cod - Multimedia
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Filter Total Items: 107
Understanding tidal marsh trajectories: Evaluation of multiple indicators of marsh persistence
Robust assessments of ecosystem stability are critical for informing conservation and management decisions. Tidal marsh ecosystems provide vital services, yet are globally threatened by anthropogenic alterations to physical and biological processes. A variety of monitoring and modeling approaches have been undertaken to determine which tidal marshes are likely to persist into the future. Here, weAuthorsKerstin Wasson, Neil K. Ganju, Zafer Defne, Charlie Endris, Tracy Elsey-Quirk, Karen M. Thorne, Chase M. Freeman, Glenn R. Guntenspergen, Daniel J. Nowacki, Kenneth B. RaposaSimple metrics predict salt-marsh sediment fluxes
The growth (or decay) of salt marshes depends on suspended-sediment flux into and out of the marsh. Suspended-sediment concentration (SSC) is a key element of the flux, and SSC-based metrics reflect the long-term sediment-flux trajectories of a variety of salt marshes. One metric, the flood–ebb SSC differential, correlates with area-normalized sediment flux and can indicate salt-marsh resilience oAuthorsDaniel J. Nowacki, Neil K. GanjuHydrodynamic and morphologic response of a back-barrier estuary to an extratropical storm
We investigated the hydrodynamic and morphologic response of Barnegat Bay-Little Egg Harbor, New Jersey, USA to Hurricane Sandy. We implemented a three-dimensional, coupled ocean-wave-sediment transport model of the estuary and explored the role of offshore water levels, offshore waves, local winds and waves by systematically removing forcings from a series of simulations. Offshore water levels haAuthorsZafer Defne, Neil K. Ganju, Julia M. MoriartyIdentifying salt marsh shorelines from remotely sensed elevation data and imagery
Salt marshes are valuable ecosystems that are vulnerable to lateral erosion, submergence, and internal disintegration due to sea-level rise, storms, and sediment deficits. Because many salt marshes are losing area in response to these factors, it is important to monitor their lateral extent at high resolution over multiple timescales. In this study we describe two methods to calculate the locationAuthorsAmy S. Farris, Zafer Defne, Neil K. GanjuSpatial distribution of water level impact to back-barrier bays
Water level in semi-enclosed bays, landward of barrier islands, is mainly driven by offshore sea level fluctuations that are modulated by bay geometry and bathymetry, causing spatial variability in the ensuing response (transfer). Local wind setup can have a secondary role that depends on wind speed, fetch, and relative orientation of the wind direction and the bay. Inlet geometry and bathymetry pAuthorsAlfredo Aretxabaleta, Neil K. Ganju, Zafer Defne, Richard P. SignellThin-layer sediment addition to an existing salt marsh to combat sea-level rise and improve endangered species habitat in California, USA
Current tidal marsh elevations and their accretion rates are important predictors of vulnerability to sea-level rise. When tidal marshes are at risk, adaptation measures, such as sediment addition to increase elevations, can be implemented to prevent degradation and loss. In 2016, wildlife managers prescribed a thin-layer sediment addition of locally sourced dredged material from Anaheim Bay to miAuthorsKaren M. Thorne, Chase M. Freeman, Jordan A. Rosencranz, Neil K. Ganju, Glenn R. GuntenspergenChanges in hydrodynamics and wave energy as a result of seagrass decline along the shoreline of a microtidal back-barrier estuary
Seagrasses are marine flowering plants that provide key ecological services. In recent decades, multiple stressors have caused a worldwide decline in seagrass beds. Changes in bottom friction associated with seagrass loss are expected to influence the ability of estuarine systems to trap sediment inputs through local and regional changes in hydrodynamics. Herein, we conduct a numerical study usingAuthorsCarmine Donatelli, Neil Kamal Ganju, Tarandeep S. Kalra, S Fagherazzi, Nicoletta LeonardiEstimating connectivity of hard clam (Mercenaria mercenaria) and eastern oyster (Crassostrea virginica) larvae in Barnegat Bay
Many marine organisms have a well-known adult sessile stage. Unfortunately, our lack of knowledge regarding their larval transient stage hinders our understanding of their basic ecology and connectivity. Larvae can have swimming behavior that influences their transport within the marine environment. Understanding the larval stage provides insight into population connectivity that can help strategiAuthorsJ.D. Goodwin, D.M. Munroe, Zafer Defne, Neil K. Ganju, James VasslidesRole of tidal wetland stability in lateral fluxes of particulate organic matter and carbon
Tidal wetland fluxes of particulate organic matter and carbon (POM, POC) are important terms in global budgets but remain poorly constrained. Given the link between sediment fluxes and wetland stability, POM and POC fluxes should also be related to stability. We measured POM and POC fluxes in eight microtidal salt marsh channels, with net POM fluxes ranging between −121 ± 33 (export) and 102 ± 28AuthorsNeil Kamal Ganju, Zafer Defne, Tracy Elsey Quirk, Julia M. MoriartyMarshes are the new beaches: Integrating sediment transport into restoration planning
Recent coastal storms and associated recovery efforts have led to increased investment in nature-based coastal protection, including restoration of salt marshes and construction of living shorelines. In particular, many of these efforts focus on increasing vertical elevation through sediment nourishment, where sediment is removed from the tidal channel and placed on the marsh plain, or preventingAuthorsNeil K. GanjuHydrologic controls of methane dynamics in karst subterranean estuaries
Karst subterranean estuaries (KSEs) extend into carbonate platforms along 12% of all coastlines. A recent study has shown that microbial methane (CH4) consumption is an important component of the carbon cycle and food web dynamics within flooded caves that permeate KSEs. In this study, we obtained high‐resolution (~2.5‐day) temporal records of dissolved methane concentrations and its stable isotopAuthorsDavid Brankovits, John W. Pohlman, Neil K. Ganju, T.M. Iliffe, N. Lowell, E. Roth, S.P. Sylva, J.A. Emmert, L. L. LaphamSalt marsh loss affects tides and sediment budget in shallow bays
The current paradigm is that salt marshes and their important ecosystem services are threatened by global climate change; indeed, large marsh losses have been documented worldwide. Morphological changes associated with salt marsh erosion are expected to influence the hydrodynamics and sediment dynamics of coastal systems. Here the influence of salt marsh erosion on the tidal hydrodynamics and sediAuthorsCarmine Donatelli, Neil K. Ganju, Xiaohe Zhang, Sergio Fagherazzi, Nicoletta LeonardiNon-USGS Publications**
Defne, Z., N. K. Ganju, and A. Aretxabaleta
(2016), Estimating time-dependent
connectivity in marine systems, Geophys.
Res. Lett., 43, doi:10.1002/2015GL066888.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.**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
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