Special Issue "Remote Sensing of Estuarine, Lagoon and Delta Environments"

A special issue of Remote Sensing (ISSN 2072-4292). This special issue belongs to the section "Remote Sensing in Geology, Geomorphology and Hydrology".

Deadline for manuscript submissions: 15 March 2020.

Special Issue Editors

Dr. Sonia Silvestri
E-Mail Website
Guest Editor
University of Padova, TESAF Legnaro (PD) 35020, Italy and Duke University, Durham, NC 27708, USA
Tel. +39 049 8272680
Interests: multispectral and hyperspectral remote sensing; organic soils, peatlands and wetlands; shallow water quality; ecogeomorpholgy of tidal systems; multi-sensor data analysis
Dr. Kevan Moffett
E-Mail Website
Guest Editor
School of the Environment, Washington State University, 14204 NE Salmon Creek Ave., Vancouver, WA, 98686, USA
Tel. +1 360 546 9413
Interests: ecohydrology; spatial patterns of plant-water relations; evapotranspiration controls and modeling; disturbance effects on ecohydrology (drought, fire, urbanization, flood/tide); watershed and wetland hydrology

Special Issue Information

Dear Colleagues,

Twenty-two out of the thirty-two world largest cities are located along estuarine, lagoon and delta shorelines, with a total population of about 350 million people. These environments provide resources, economic benefits, and ecosystem services for humans and host thousands of species of birds, fish, mammals, and other wildlife that live, feed, and reproduce in these environments.

The morphologies, biota and water quality of these environments are characterized by rapid and sometimes extreme changes, in response to natural and anthropogenic pressures. In fact, estuaries, deltas and lagoons are extremely dynamic transition ecosystems, characterized by rapid morphological and ecological modifications. Moreover, the impact of the large anthropic presence on these systems strongly accelerates such rapid dynamics, often producing irreversible and sometimes catastrophic consequences.

In short, shallow water environments around the world are suffering because of increased human pressure, and are experiencing dramatic degradation, particularly because of increasing pollution of water and sediments. Pollutant discharge is just one of the several challenges that these systems are currently facing, together with sea level rise, increased frequency and magnitude of storm surges, lack of sediment supply from watersheds, and frequent morphological modifications due to direct human interventions and management. In spite of these alarming trends, remote sensing applications for monitoring water quality and morphology in shallow coastal environments are still lacking. This is mainly due to the complexity of these systems and of the interactions among physical and biological forcings that characterize them.

The present Special Issue aims at collecting high quality papers that focus on the use of remote sensing for studying and monitoring lagoons, deltas and estuaries around the world. Contributions on the integration of remote sensing observations into mathematical models of earth surface and shallow water dynamics are especially encouraged.

The special issue will include, but will not be limited to, the following topics:

  • Recent developments and new approaches to the assessment and monitoring of the quality of shallow waters in coastal systems.
  • New methods and algorithms for the retrieval of water constituents (suspended matter, chlorophyll, etc.) in optically deep and complex waters.
  • Assimilation/integration of remote sensing observations into mathematical models (i.e., hydrodynamic models; geomorphodynamic models; hydrological models; ecological models) of estuaries, deltas and lagoons.
  • Use of airborne and satellite sensors for bathymetric retrievals in coastal turbid waters.
  • Estuarine, delta and lagoon ecosystems studies based on remote sensing observations.
  • Change detection and quantification of morphological changes in semi-enclosed coastal systems and deltas.
  • Remote sensing of mangroves, salt marshes, seagrass meadows, tidal wetlands and tidal flats.
  • Use of remote sensing for the assessment of the anthropic pressure on coastal wetlands, lagoons, deltas and estuaries.
  • Remote sensing applied to the management of lagoons, deltas and estuaries.
Dr. Sonia Silvestri
Dr. Kevan Moffett
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Remote Sensing is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2000 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Water quality
  • Optically deep complex shallow waters
  • Bathymetry
  • Data assimilation
  • Geomorphology and eco-
  • Change detection
  • Mangroves
  • Salt marshes
  • Seagrass meadows
  • Coastal wetlands
  • Tidal systems
  • Management

Published Papers (7 papers)

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Open AccessArticle
Photophysiology and Spectroscopy of Sun and Shade Leaves of Phragmites australis and the Effect on Patches of Different Densities
Remote Sens. 2020, 12(1), 200; https://doi.org/10.3390/rs12010200 - 06 Jan 2020
Abstract
Remote sensing of vegetation has largely been revolving around the measurement of passive or active electromagnetic radiation of the top of the canopy. Nevertheless, plants hold a vertical structure and different processes and intensities take place within a plant organism depending on the [...] Read more.
Remote sensing of vegetation has largely been revolving around the measurement of passive or active electromagnetic radiation of the top of the canopy. Nevertheless, plants hold a vertical structure and different processes and intensities take place within a plant organism depending on the environmental conditions. One of the main inputs for photosynthesis is photosynthetic active radiation (PAR) and a few studies have taken into account the effect of the qualitative and quantitative changes of the available PAR within the plants canopies. Mostly large plants (trees, shrubs) are affected by this phenomena, while signs of it could be observed in dense monocultures, too. Lake Balaton is a large lake with 12 km2 dense reed stands, some of which have been suffering from reed die-back; consequently, the reed density and stress condition exhibit a vertical PAR variability within the canopy due to the structure and condition of the plants but also a horizontal variability attributed to the reedbed’s heterogeneous density. In this study we investigate the expression of photosynthetic and spectroscopic parameters in different PAR conditions. We concentrate on chlorophyll fluorescence as this is an early-stage indicator of stress manifestation in plants. We first investigate how these parameters differ across leaf samples which are exposed to a higher degree of PAR variability due to their vertical position in the reed culm (sun and shade leaves). In the second part, we concentrate on how the same parameters exhibit in reed patches of different densities. We then look into hyperspectral regions through graphs of coefficient of determination and associate the former with the physiological parameters. We report on the large variability found from measurements taken at different parts of the canopy and the association with spectral regions in the visible and near-infrared domain. We find that at low irradiance plants increase their acclimation to low light conditions. Plant density at Phragmites stands affects the vertical light attenuation and consequently the photophysiological response of basal leaves. Moreover, the hyperspectral response from the sun and shade leaves has been found to differ; charts of the coefficient of determination indicate that the spectral region around the red-edge inflection point for each case of sun and shade leaves correlate strongly with ETRmax and α. When analysing the data cumulatively, independent of their vertical position within the stand, we found correlations of R2 = 0.65 (band combination 696 and 651) and R2 = 0.61 (band combination 636 and 642) for the ETRmax and α, respectively. Full article
(This article belongs to the Special Issue Remote Sensing of Estuarine, Lagoon and Delta Environments)
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Open AccessFeature PaperArticle
Remote Sensing for Optimal Estimation of Water Temperature Dynamics in Shallow Tidal Environments
Remote Sens. 2020, 12(1), 51; https://doi.org/10.3390/rs12010051 - 21 Dec 2019
Abstract
Given the increasing anthropogenic pressures on lagoons, estuaries, and lakes and considering the highly dynamic behavior of these systems, methods for the continuous and spatially distributed retrieval of water quality are becoming vital for their correct monitoring and management. Water temperature is certainly [...] Read more.
Given the increasing anthropogenic pressures on lagoons, estuaries, and lakes and considering the highly dynamic behavior of these systems, methods for the continuous and spatially distributed retrieval of water quality are becoming vital for their correct monitoring and management. Water temperature is certainly one of the most important drivers that influence the overall state of coastal systems. Traditionally, lake, estuarine, and lagoon temperatures are observed through point measurements carried out during field campaigns or through a network of sensors. However, sporadic measuring campaigns or probe networks rarely attain a density sufficient for process understanding, model development/validation, or integrated assessment. Here, we develop and apply an integrated approach for water temperature monitoring in a shallow lagoon which incorporates satellite and in-situ data into a mathematical model. Specifically, we use remote sensing information to constrain large-scale patterns of water temperature and high-frequency in situ observations to provide proper time constraints. A coupled hydrodynamic circulation-heat transport model is then used to propagate the state of the system forward in time between subsequent remote sensing observations. Exploiting the satellite data high spatial resolution and the in situ measurements high temporal resolution, the model may act a physical interpolator filling the gap intrinsically characterizing the two monitoring techniques. Full article
(This article belongs to the Special Issue Remote Sensing of Estuarine, Lagoon and Delta Environments)
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Open AccessFeature PaperArticle
Detecting the Morphology of Prograding and Retreating Marsh Margins—Example of a Mega-Tidal Bay
Remote Sens. 2020, 12(1), 13; https://doi.org/10.3390/rs12010013 - 18 Dec 2019
Abstract
Retreat and progradation make the edges of salt marsh platforms their most active features. If we have a single topographic snapshot of a marsh, is it possible to tell if some areas have retreated or prograded recently or if they are likely to [...] Read more.
Retreat and progradation make the edges of salt marsh platforms their most active features. If we have a single topographic snapshot of a marsh, is it possible to tell if some areas have retreated or prograded recently or if they are likely to do so in the future? We explore these questions by characterising marsh edge topography in mega-tidal Moricambe Bay (UK) in 2009, 2013 and 2017. We first map outlines of marsh platform edges based on lidar data and from these we generate transverse topographic profiles of the marsh edge 10 m long and 20 m apart. By associating profiles with individual retreat or progradation events, we find that they produce distinct profiles when grouped by change event, regardless of event magnitude. Progradation profiles have a shallow scarp and low relief that decreases with event magnitude, facilitating more progradation. Conversely, steep-scarped, high-relief retreat profiles dip landward as retreat reveals older platforms. Furthermore, vertical accretion of the marsh edge is controlled by elevation rather than its lateral motion, suggesting an even distribution of deposition that would allow bay infilling were it not limited by the migration of creeks. While we demonstrate that marsh edges can be quantified with currently available DTMs, oblique observations are crucial to fully describe scarps and better inform their sensitivity to wave and current erosion. Full article
(This article belongs to the Special Issue Remote Sensing of Estuarine, Lagoon and Delta Environments)
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Open AccessFeature PaperArticle
Variations in Persistence and Regenerative Zones in Coastal Forests Triggered by Sea Level Rise and Storms
Remote Sens. 2019, 11(17), 2019; https://doi.org/10.3390/rs11172019 - 28 Aug 2019
Abstract
Retreat of coastal forests in relation to sea level rise has been widely documented. Recent work indicates that coastal forests on the Delmarva Peninsula, United States, can be differentiated into persistence and regenerative zones as a function of sea-level rise and storm events. [...] Read more.
Retreat of coastal forests in relation to sea level rise has been widely documented. Recent work indicates that coastal forests on the Delmarva Peninsula, United States, can be differentiated into persistence and regenerative zones as a function of sea-level rise and storm events. In the lower persistence zone trees cannot regenerate because of frequent flooding and high soil salinity. This study aims to verify the existence of these zones using spectral remote sensing data, and determine whether the effect of large storm events that cause damage to these forests can be detected from satellite images. Spectral analysis confirms a significant difference in average Normalized Difference Vegetation Index (NDVI) and Normalized Difference Water Index (NDWI) values in the proposed persistence and regenerative zones. Both NDVI and NDWI indexes decrease after storms triggering a surge above 1.3 m with respect to the North American Vertical Datum of 1988 (NAVD88). NDWI values decrease more, suggesting that this index is better suited to detect the effect of hurricanes on coastal forests. In the regenerative zone, both NDVI and NDWI values recover three years after a storm, while in the persistence zone the NDVI and NDWI values keep decreasing, possibly due to sea level rise causing vegetation stress. As a result, the forest resilience to storms in the persistence zone is lower than in the regenerative zone. Our findings corroborate the ecological ratchet model of coastal forest disturbance. Full article
(This article belongs to the Special Issue Remote Sensing of Estuarine, Lagoon and Delta Environments)
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Open AccessArticle
Potential of High-Resolution Pléiades Imagery to Monitor Salt Marsh Evolution After Spartina Invasion
Remote Sens. 2019, 11(8), 968; https://doi.org/10.3390/rs11080968 - 23 Apr 2019
Cited by 2
Abstract
An early assessment of biological invasions is important for initiating conservation strategies. Instrumental progress in high spatial resolution (HSR) multispectral satellite sensors greatly facilitates ecosystems’ monitoring capability at an increasingly smaller scale. However, species detection is still challenging in environments characterized by a [...] Read more.
An early assessment of biological invasions is important for initiating conservation strategies. Instrumental progress in high spatial resolution (HSR) multispectral satellite sensors greatly facilitates ecosystems’ monitoring capability at an increasingly smaller scale. However, species detection is still challenging in environments characterized by a high variability of vegetation mixing along with other elements, such as water, sediment, and biofilm. In this study, we explore the potential of Pléiades HSR multispectral images to detect and monitor changes in the salt marshes of the Bay of Arcachon (SW France), after the invasion of Spartina anglica. Due to the small size of Spartina patches, the spatial and temporal monitoring of Spartina species focuses on the analysis of five multispectral images at a spatial resolution of 2 m, acquired at the study site between 2013 and 2017. To distinguish between the different types of vegetation, various techniques for land use classification were evaluated. A description and interpretation of the results are based on a set of ground truth data, including field reflectance, a drone flight, historical aerial photographs, GNSS and photographic surveys. A preliminary qualitative analysis of NDVI maps showed that a multi-temporal approach, taking into account a delayed development of species, could be successfully used to discriminate Spartina species (sp.). Then, supervised and unsupervised classifications, used for the identification of Spartina sp., were evaluated. The performance of the species identification was highly dependent on the degree of environmental noise present in the image, which is season-dependent. The accurate identification of the native Spartina was higher than 75%, a result strongly affected by intra-patch variability and, specifically, by the presence of areas with a low vegetation density. Further, for the invasive Spartina anglica, when using a supervised classifier, rather than an unsupervised one, the accuracy of the classification increases from 10% to 90%. However, both algorithms highly overestimate the areas assigned to this species. Finally, the results highlight that the identification of the invasive species is highly dependent both on the seasonal presence of itinerant biological features and the size of vegetation patches. Further, we believe that the results could be strongly improved by a coupled approach, which combines spectral and spatial information, i.e., pattern-recognition techniques. Full article
(This article belongs to the Special Issue Remote Sensing of Estuarine, Lagoon and Delta Environments)
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Open AccessCommunication
Impact of Coastal Infrastructure on Ocean Colour Remote Sensing: A Case Study in Jiaozhou Bay, China
Remote Sens. 2019, 11(8), 946; https://doi.org/10.3390/rs11080946 - 19 Apr 2019
Abstract
Spatial and temporal ocean colour data are increasingly accessible through remote sensing, which is a key tool for evaluating coastal biogeochemical and physical processes, and for monitoring water quality. Coastal infrastructure such as cross-sea bridges may impact ocean colour remote sensing due to [...] Read more.
Spatial and temporal ocean colour data are increasingly accessible through remote sensing, which is a key tool for evaluating coastal biogeochemical and physical processes, and for monitoring water quality. Coastal infrastructure such as cross-sea bridges may impact ocean colour remote sensing due to the different spectral characteristics of asphalt and the seawater surface. However, this potential impact is typically ignored during data post-processing. In this study, we use Jiaozhou Bay (East China) and its cross-bay bridge to examine the impact of coastal infrastructure on water-quality remote-sensing products, in particular on chlorophyll-a concentration and total suspended sediment. The values of these products in the bridge area were significantly different to those in the adjacent water. Analysis of the remote-sensing reflectance and application of the Normalised Difference Water Index demonstrate that this phenomenon is caused by contamination of the signal by bridge pixels. The Moderate Resolution Imaging Spectroradiometer (MODIS) products helped estimate the pixel scale that could be influenced by contamination. Furthermore, we found similar pixel contamination at Hangzhou Bay Bridge, suggesting that the impact of large coastal infrastructure on ocean colour data is common, and must therefore be considered in data post-processing. Full article
(This article belongs to the Special Issue Remote Sensing of Estuarine, Lagoon and Delta Environments)
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Open AccessLetter
Validation of Streaklines as Recorders of Synoptic Flow Direction in a Deltaic Setting
Remote Sens. 2020, 12(1), 148; https://doi.org/10.3390/rs12010148 - 02 Jan 2020
Abstract
Knowledge of the flow patterns within distributary systems is key for understanding deltaic hydro- and morpho-dynamics, yet synoptic measurements of flow fields remain virtually nonexistent. As a means of overcoming this problem, a small number of studies have used biogenic surface films as [...] Read more.
Knowledge of the flow patterns within distributary systems is key for understanding deltaic hydro- and morpho-dynamics, yet synoptic measurements of flow fields remain virtually nonexistent. As a means of overcoming this problem, a small number of studies have used biogenic surface films as synoptic flow tracers, under the assumption that biofilm streaklines are tangent to the local flow direction. Here we rigorously test this assumption and show that, despite flow patterns that change severely in space and time (over a range >270°), streaklines are relatively accurate synoptic flow tracers for the Wax Lake Delta, in Louisiana. When the incoming discharge was greater than 2400 m3/s with stable or falling tides, the streakline-derived flow direction departed from near bed flow direction measurements of 22.8° (root mean square). When the discharge was greater than 2400 m3/s and the tides were rising greater than 0.03 m/hr, they were accurate within 28.0°. Under conditions of discharge less than 2400 m3/s and tidal change less than a positive 0.03 m/hr, they were accurate within 33.3°, while during low discharge and rising tides they were accurate within 58.9°. Accuracy varied with distance from the delta, with proximal sites having greater precision. Our results demonstrate that a streakline-derived flow direction can characterize the spatiotemporal variability in the flow directions, but that the accuracy is significantly influenced by the hydrodynamic conditions and location within the network. Full article
(This article belongs to the Special Issue Remote Sensing of Estuarine, Lagoon and Delta Environments)
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Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.

Title: Remote sensing for the optimal estimation of the water temperature dynamics in shallow tidal environments
Authors: Pivato M., Carniello L., Viero D., Defina A, Silvestri S.
Abstract: Giving the increasing anthropogenic pressures on lagoons, estuaries and coastal areas and considering the highly dynamic behavior of these systems, methods for the continuous and spatially-distributed retrieval of water quality are becoming vital for a correct monitoring and management. Traditionally, estuarine and lagoon water properties and their dynamics are observed through point measurements carried out during field campaigns or, in the best scenarios, through a network of sensors. However, sporadic measuring campaigns or probe networks rarely attain a density sufficient for process understanding, model development/validation, or integrated assessment. In this contribution, we develop and apply an integrated approach for water quality monitoring in a shallow lagoon, which incorporates satellite and in-situ water quality data into mathematical models. Specifically, we use remote sensing information to constrain large-scale patterns of water temperature and high-frequency in-situ observations to provide proper time constraints. A coupled hyrodynamic circulation/ heat transport model is then used to propagate the state of the system forward in time between subsequent remote sensing observations. The description of the water temperature dynamic is the starting point for the development of circulation models of other water quality properties/constituents as well as for future development of ecological models.

Title: UAVs to assess channels’ shape evolution in a restored salt marsh
Authors: Yuri Taddia1,2 and William Nardin1
Affiliation: 1 Horn point laboratory, University of Maryland Center for Environmental Science, Cambridge, MD USA; 2 Engineering Department, University of Ferrara, Italy
Abstract: Salt marsh evolution is strongly affected by tidal processes which regulate sediment accretion rates and vegetated platform erosion. A balance between erosion and deposition in a restored salt marsh is crucial for analyzing restoration strategies to adopt in a natural context. Here, we present an integrated approach monitoring channels morphodynamic over a few years’ time frame in a low energy salt marsh of the Paul S. Sarbanes Ecosystem Restoration Project at Poplar Island (Maryland, USA). The project is a restoration site where sediment dredged from the shipping channels in the upper Chesapeake Bay is being used to restore a tidal marsh habitat in mid-Chesapeake Bay. Starting from the cross section of every channel measured in the initial project GNSS survey, then, a detection has been performed using both a traditional GNSS Real Time Kinematic for the accurate cross sections survey and an Unmanned Aerial Vehicle (UAV) to high resolution map the planimetric position of the channels and the vegetation’s platform. Due to its extension of 400m by 400m, a total of three flight plans was necessary to cover the entire cell flying at a 40m altitude, in order to obtain a 2cm Ground Sample Distance (GSD). This technique provides reliable results at a very low cost, allowing an accurate assessment of the channels dynamics over time, thanks to both the very high spatial resolution and the precise georeferencing of the images for the comparisons. Detecting tidal channels morphodynamic coupled with suspended sediment concentration recorded through Aqua Doppler Current Profilers (ADCPs) deployment and suspended sediment samples can help to improve the accuracy of numerical models. Understanding the drivers of salt marsh evolution is vital for informing restoration practices and designs to improve resilience and coastal management strategies.

Title: Persistent and regenerative zones triggered by sea level rise in the coastal forest of the Delmarva Peninsula, USA
Authors: Keila Munz, William Kearney, Sergio Fagherazzi
Affiliation: Department of Earth and Environment, Boston University
Abstract : How ecosystems respond to climate change and related events is of key interest to understand how our environment will adapt and change in the coming years. Retreat of coastal forests in relation to sea level rise has been widely documented. Resent work indicates that coastal forests on the Delmarva Peninsula, United States, can be differentiated into persistent and regenerating zones as a function of sea-level rise and storm events in this area. This study aims to verify the existence of these zones using spectral remote sensing data and determine whether the effect of large storm events that cause damage to these forests can be detected from satellite images. Spectral analysis confirmed a significant difference in average NDVI values in the proposed persistent and regenerative zones, however further analysis is needed to fully assess the reliability of using remote sensing data to identify storm events.

Title: Formation and evolution of the sandy spit ramifications detected on aerial and satellite images in the Po river delta, Italy
Authors: Corinne Corbau1,2, Umberto Simeoni2 and William Nardin1
Affiliation: 1 Horn point laboratory, University of Maryland Center for Environmental Science, Cambridge, MD USA; 2Department of Physics and Earth Sciences, University of Ferrara, Italy
Abstract: Coastal barriers and spits are often extremely dynamic due to the interactions between wave climate and sediment availability. Sandy spits have been extensively studied because they represent an important natural protection acting as a buffer zone for coastal flooding. In addition, they provide an excellent natural habitat, increasing tourism and economical benefit. Sandy spit morphology is influenced by the geological framework, sea-level rise, subsidence, sediment availability, winds and tides and human interventions. Our study focus on the spit of Goro, located in the southern part of the Po river delta (Italy).
Historical maps indicate that the spit formed at the end of the 19th century and was abandoned, destroyed, and re-constructed several times because of the development of newer spits seaward. During the last years, the Goro’s spit presented a branched shape growth characterized by small ramifications, mostly ephemeral. Our preliminary results aim to understand the formation and the evolution of new ramifications along the spit of Goro. Our work combines recent aerial photogrammetry, satellite images, meteorological data, topobathymetrical data and wave numerical simulations to investigates the spit morphodynamic.
Numerous ramifications have been mapped along the spit at different positions. For instance, in 2001, 31 ramifications were present along the spit, while, 9 ramifications were observed in 2009. Their dimensions change with length ranging from 10 m to up to 350 m. The angle between the shoreline and the ramification’s direction is usually about 15° but can reach 90°. The combination of numerical model simulations and remote sensing analysis might improve the understanding on the geomorphological evolution of sandy spit.

Title: Scale-dependence of fluvial delta morphodynamic equilibration: multi-scale differentiation of elevations evidenced by decades of remote sensing-based topset topography hindcasting
Authors: Kevan B. Moffett1, Brittany C. Smith2, David Morhig2
Affiliations: 1 School of the Environment, Washington State University Vancouver; 2 Department of Geological Sciences, The University of Texas at Austin
Abstract: Understanding how delta islands grow and change over time is critical to predicting the stability of diverse coastal habitats and the valuable coastal protections they provide. Complete morphologic mapping of complex delta geometries in situ as they evolve in four dimensions (space + time) is usually infeasible, however; manual methods are laborious, aerial surveys expensive, and satellite data typically unable to sufficiently resolve the vertical dimension. Many settings present the additional challenge of incompletely gauged water levels. This paper presents a new method for probabilistically hindcasting emergent delta island morphologies and dynamics based on only partial water level records and frequent and easily available optical remote sensing data, such as from Landsat. The method was applied to investigate spatial and temporal patterns of sediment accumulation and vegetation colonization on the Wax Lake Delta in Louisiana over multiple decades of recent and rapid morphodynamic change. The method enabled quantifying delta-wide and location-specific estimates of topset sediment deposition or erosion over time at elevations near or above mean water level. Net patterns of delta-wide elevation change over multiple decades appeared aligned with the major wetland vegetation zones, evidencing a freshwater marsh case of the ecogeomorphological alternative stable state theory often applied to saline marshes. Although at the delta-scale the mean emergent elevation gradually stabilized over time, this did not reflect achievement of a bulk geomorphic equilibrium but instead was the result of the ongoing differentiation of the delta into distinct high (and growing higher), mid (and accreting), and low (stable) topographic platforms. Erosion at the intervening elevations provided the platform sediment sources and balanced out the accretion, on average across the delta. At the island scale, progressive topographic differentiation related to vegetation zones was also exhibited, which exacerbated the intra-island levee/lagoon elevation difference over time. Intra-island topography did not equilibrate over the same time scale as the whole delta, however; it instead showed continued reorganization of sediments to support growth of island mouth-bars/levee complexes into ever-stronger chevron-shaped islands. The presented method of morphologic hindcasting provides a novel tool to generate four-dimensional, historical topographic data for active fluvial settings, while the empirical findings from Wax Lake Delta provide a new opportunity to review existing theories and model representations of fluvial delta morphodynamic change across multiple spatial scales.

Title: Detection of disturbance in coastal wetlands using GEOBIA and pixel-based classification of LANDSAT 8 and high-resolution aerial imagery
Authors: Elisabeth. P. Powell, Lin Perez, Scott Haag, and Elizabeth B. Watson

Title: Developing a Spatiotemporal Estuarine Water Quality Parameterization Model unsing MODIS and In-situ Characteristics
Authors: Kwisun Park (National Research Foundation of Korea)

 

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