Zafer Defne, PhD
My research finds its form in providing answers to questions related to coasts and ocean, based on my knowledge of physical oceanography and experience in data sciences.
Dr. Zafer Defne received his PhD in Coastal and Ocean Engineering from Georgia Institute of Technology, with a minor in Information Technology Applications in Oceanography. His expertise includes computational fluid dynamics and data analysis. His work on numerical modeling of coastal ocean has been used to assess storm surge, residual circulation, sediment transport and water quality, as well as marine renewable energy. His recent research is on assessment of the physical state of coastal wetlands using geospatial data.
Google Scholar
Science and Products
Filter Total Items: 55
Lifespan of marsh units in Eastern Shore of Virginia salt marshes Lifespan of marsh units in Eastern Shore of Virginia salt marshes
The lifespans of salt marshes in Atlantic-facing Eastern Shore of Virginia are calculated based on estimated sediment supply and sea-level rise (SLR) predictions, following the methodology of Ganju and others (2020). The salt marsh delineations are from Ackerman and others (2023). The SLR predictions are local estimates corresponding to increases of 0.3, 0.5 and 1.0 meter in global mean...
Lifespan of marsh units in Connecticut salt marshes Lifespan of marsh units in Connecticut salt marshes
The lifespans of salt marshes in Connecticut are calculated based on estimated sediment supply and sea-level rise (SLR) predictions, following the methodology of Ganju and others (2020). The salt marsh delineations are from Ackerman and others (2023). The SLR predictions are local estimates corresponding to increases of 0.3, 0.5 and 1.0 meter in global mean sea level (GMSL) by 2100, as...
Lifespan of marsh units in New York salt marshes Lifespan of marsh units in New York salt marshes
Lifespan of salt marshes in New York are calculated using conceptual marsh units defined by Defne and Ganju (2018) and Welk and others (2019, 2020a, 2020b, 2020c). The lifespan calculation is based on estimated sediment supply and sea-level rise (SLR) predictions after Ganju and others (2020). Sea level predictions are local estimates which correspond to the 0.3, 0.5, and 1.0 meter...
Geospatial characterization of salt marshes in Maine Geospatial characterization of salt marshes in Maine
This data release contains coastal wetland synthesis products for the state of Maine. Metrics for resiliency, including the unvegetated to vegetated ratio (UVVR), marsh elevation, tidal range, and lifespan, are calculated for smaller units delineated from a digital elevation model, providing the spatial variability of physical factors that influence wetland health. The U.S. Geological...
Geospatial characterization of salt marshes in Connecticut (ver. 2.0, April 2024) Geospatial characterization of salt marshes in Connecticut (ver. 2.0, April 2024)
This data release contains coastal wetland synthesis products for the state of Connecticut. Metrics for resiliency, including the unvegetated to vegetated ratio (UVVR), marsh elevation, tidal range, wave power, and exposure potential to environmental health stressors are calculated for smaller units delineated from a digital elevation model, providing the spatial variability of physical...
Inventory of Managed Coastal Wetlands in Delaware Bay and Delaware's Inland Bays Inventory of Managed Coastal Wetlands in Delaware Bay and Delaware's Inland Bays
This data release contains areas within Delaware Bay and Delaware Inland Bays that are within tidal elevations, as determined by the Highest Astronomical Tide (HAT), but that are classified as non-tidal or managed wetlands by the National Wetlands Inventory (NWI) or as non-estuarine by the 2016 Coastal Change Analysis Program (C-CAP) land cover dataset. These areas have been assigned the
Filter Total Items: 26
Horizontal integrity a prerequisite for vertical stability: Comparison of elevation change and the unvegetated-vegetated marsh ratio across southeastern USA coastal wetlands Horizontal integrity a prerequisite for vertical stability: Comparison of elevation change and the unvegetated-vegetated marsh ratio across southeastern USA coastal wetlands
Surface elevation tables (SETs) estimate the vertical resilience of coastal wetlands to sea-level rise (SLR) and other stressors but are limited in their spatial coverage. Conversely, spatially integrative metrics based on remote sensing provide comprehensive spatial coverage of horizontal processes but cannot track elevation trajectory at high resolution. Here, we present a critical...
Authors
Neil K. Ganju, Zafer Defne, Caroline Schwab, Michelle Moorman
Development and application of Landsat-based wetland vegetation cover and unvegetated-vegetated marsh ratio (UVVR) for the conterminous United States Development and application of Landsat-based wetland vegetation cover and unvegetated-vegetated marsh ratio (UVVR) for the conterminous United States
Effective management and restoration of salt marshes and other vegetated intertidal habitats require objective and spatially integrated metrics of geomorphic status and vulnerability. The unvegetated-vegetated marsh ratio (UVVR), a recently developed metric, can be used to establish present-day vegetative cover, identify stability thresholds, and quantify vulnerability to open-water...
Authors
Neil K. Ganju, Brady Couvillion, Zafer Defne, Kate Ackerman
Modeling marsh dynamics using a 3-D coupled wave-flow-sediment model Modeling marsh dynamics using a 3-D coupled wave-flow-sediment model
Salt marshes are dynamic biogeomorphic systems that respond to external physical factors, including tides, sediment transport, and waves, as well as internal processes such as autochthonous soil formation. Predicting the fate of marshes requires a modeling framework that accounts for these processes in a coupled fashion. In this study, we implement two new marsh dynamic processes in the...
Authors
Tarandeep S. Kalra, Neil K. Ganju, Alfredo Aretxabaleta, Joel A. Carr, Zafer Defne, Julia Moriarty
Quantifying slopes as a driver of forest to marsh conversion using geospatial techniques: Application to Chesapeake Bay coastal-plain, USA Quantifying slopes as a driver of forest to marsh conversion using geospatial techniques: Application to Chesapeake Bay coastal-plain, USA
Coastal salt marshes, which provide valuable ecosystem services such as flood mitigation and carbon sequestration, are threatened by rising sea level. In response, these ecosystems migrate landward, converting available upland into salt marsh. In the coastal-plain surrounding Chesapeake Bay, United States, conversion of coastal forest to salt marsh is well-documented and may offset salt...
Authors
Grace Damore Molino, Zafer Defne, Alfredo Aretxabaleta, Neil K. Ganju, Joel A. Carr
A geospatially resolved wetland vulnerability index: Synthesis of physical drivers A geospatially resolved wetland vulnerability index: Synthesis of physical drivers
Assessing wetland vulnerability to chronic and episodic physical drivers is fundamental for establishing restoration priorities. We synthesized multiple data sets from E.B Forsythe National Wildlife Refuge, New Jersey, to establish a wetland vulnerability metric that integrates a range of physical processes, regulatory information and physical/biophysical features. The geospatial data...
Authors
Zafer Defne, Alfredo Aretxabaleta, Neil K. Ganju, Tarandeep S. Kalra, Daniel K. Jones, Kathryn Smith
Are elevation and open-water conversion of salt marshes connected? Are elevation and open-water conversion of salt marshes connected?
Salt marsh assessments focus on vertical metrics such as accretion or lateral metrics such as open-water conversion, without exploration of how the dimensions are related. We exploited a novel geospatial dataset to explore how elevation is related to the unvegetated-vegetated marsh ratio (UVVR), a lateral metric, across individual marsh “units” within four estuarine-marsh systems. We...
Authors
Neil K. Ganju, Zafer Defne, Sergio Fagherazzi
Science and Products
Filter Total Items: 55
Lifespan of marsh units in Eastern Shore of Virginia salt marshes Lifespan of marsh units in Eastern Shore of Virginia salt marshes
The lifespans of salt marshes in Atlantic-facing Eastern Shore of Virginia are calculated based on estimated sediment supply and sea-level rise (SLR) predictions, following the methodology of Ganju and others (2020). The salt marsh delineations are from Ackerman and others (2023). The SLR predictions are local estimates corresponding to increases of 0.3, 0.5 and 1.0 meter in global mean...
Lifespan of marsh units in Connecticut salt marshes Lifespan of marsh units in Connecticut salt marshes
The lifespans of salt marshes in Connecticut are calculated based on estimated sediment supply and sea-level rise (SLR) predictions, following the methodology of Ganju and others (2020). The salt marsh delineations are from Ackerman and others (2023). The SLR predictions are local estimates corresponding to increases of 0.3, 0.5 and 1.0 meter in global mean sea level (GMSL) by 2100, as...
Lifespan of marsh units in New York salt marshes Lifespan of marsh units in New York salt marshes
Lifespan of salt marshes in New York are calculated using conceptual marsh units defined by Defne and Ganju (2018) and Welk and others (2019, 2020a, 2020b, 2020c). The lifespan calculation is based on estimated sediment supply and sea-level rise (SLR) predictions after Ganju and others (2020). Sea level predictions are local estimates which correspond to the 0.3, 0.5, and 1.0 meter...
Geospatial characterization of salt marshes in Maine Geospatial characterization of salt marshes in Maine
This data release contains coastal wetland synthesis products for the state of Maine. Metrics for resiliency, including the unvegetated to vegetated ratio (UVVR), marsh elevation, tidal range, and lifespan, are calculated for smaller units delineated from a digital elevation model, providing the spatial variability of physical factors that influence wetland health. The U.S. Geological...
Geospatial characterization of salt marshes in Connecticut (ver. 2.0, April 2024) Geospatial characterization of salt marshes in Connecticut (ver. 2.0, April 2024)
This data release contains coastal wetland synthesis products for the state of Connecticut. Metrics for resiliency, including the unvegetated to vegetated ratio (UVVR), marsh elevation, tidal range, wave power, and exposure potential to environmental health stressors are calculated for smaller units delineated from a digital elevation model, providing the spatial variability of physical...
Inventory of Managed Coastal Wetlands in Delaware Bay and Delaware's Inland Bays Inventory of Managed Coastal Wetlands in Delaware Bay and Delaware's Inland Bays
This data release contains areas within Delaware Bay and Delaware Inland Bays that are within tidal elevations, as determined by the Highest Astronomical Tide (HAT), but that are classified as non-tidal or managed wetlands by the National Wetlands Inventory (NWI) or as non-estuarine by the 2016 Coastal Change Analysis Program (C-CAP) land cover dataset. These areas have been assigned the
Filter Total Items: 26
Horizontal integrity a prerequisite for vertical stability: Comparison of elevation change and the unvegetated-vegetated marsh ratio across southeastern USA coastal wetlands Horizontal integrity a prerequisite for vertical stability: Comparison of elevation change and the unvegetated-vegetated marsh ratio across southeastern USA coastal wetlands
Surface elevation tables (SETs) estimate the vertical resilience of coastal wetlands to sea-level rise (SLR) and other stressors but are limited in their spatial coverage. Conversely, spatially integrative metrics based on remote sensing provide comprehensive spatial coverage of horizontal processes but cannot track elevation trajectory at high resolution. Here, we present a critical...
Authors
Neil K. Ganju, Zafer Defne, Caroline Schwab, Michelle Moorman
Development and application of Landsat-based wetland vegetation cover and unvegetated-vegetated marsh ratio (UVVR) for the conterminous United States Development and application of Landsat-based wetland vegetation cover and unvegetated-vegetated marsh ratio (UVVR) for the conterminous United States
Effective management and restoration of salt marshes and other vegetated intertidal habitats require objective and spatially integrated metrics of geomorphic status and vulnerability. The unvegetated-vegetated marsh ratio (UVVR), a recently developed metric, can be used to establish present-day vegetative cover, identify stability thresholds, and quantify vulnerability to open-water...
Authors
Neil K. Ganju, Brady Couvillion, Zafer Defne, Kate Ackerman
Modeling marsh dynamics using a 3-D coupled wave-flow-sediment model Modeling marsh dynamics using a 3-D coupled wave-flow-sediment model
Salt marshes are dynamic biogeomorphic systems that respond to external physical factors, including tides, sediment transport, and waves, as well as internal processes such as autochthonous soil formation. Predicting the fate of marshes requires a modeling framework that accounts for these processes in a coupled fashion. In this study, we implement two new marsh dynamic processes in the...
Authors
Tarandeep S. Kalra, Neil K. Ganju, Alfredo Aretxabaleta, Joel A. Carr, Zafer Defne, Julia Moriarty
Quantifying slopes as a driver of forest to marsh conversion using geospatial techniques: Application to Chesapeake Bay coastal-plain, USA Quantifying slopes as a driver of forest to marsh conversion using geospatial techniques: Application to Chesapeake Bay coastal-plain, USA
Coastal salt marshes, which provide valuable ecosystem services such as flood mitigation and carbon sequestration, are threatened by rising sea level. In response, these ecosystems migrate landward, converting available upland into salt marsh. In the coastal-plain surrounding Chesapeake Bay, United States, conversion of coastal forest to salt marsh is well-documented and may offset salt...
Authors
Grace Damore Molino, Zafer Defne, Alfredo Aretxabaleta, Neil K. Ganju, Joel A. Carr
A geospatially resolved wetland vulnerability index: Synthesis of physical drivers A geospatially resolved wetland vulnerability index: Synthesis of physical drivers
Assessing wetland vulnerability to chronic and episodic physical drivers is fundamental for establishing restoration priorities. We synthesized multiple data sets from E.B Forsythe National Wildlife Refuge, New Jersey, to establish a wetland vulnerability metric that integrates a range of physical processes, regulatory information and physical/biophysical features. The geospatial data...
Authors
Zafer Defne, Alfredo Aretxabaleta, Neil K. Ganju, Tarandeep S. Kalra, Daniel K. Jones, Kathryn Smith
Are elevation and open-water conversion of salt marshes connected? Are elevation and open-water conversion of salt marshes connected?
Salt marsh assessments focus on vertical metrics such as accretion or lateral metrics such as open-water conversion, without exploration of how the dimensions are related. We exploited a novel geospatial dataset to explore how elevation is related to the unvegetated-vegetated marsh ratio (UVVR), a lateral metric, across individual marsh “units” within four estuarine-marsh systems. We...
Authors
Neil K. Ganju, Zafer Defne, Sergio Fagherazzi