Remote Sensing of Coastal Resources
The Research Group of Dr. Vic Klemas
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Remote Sensing
of Wetland Biomass
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NOAA/NERRS Remote Sensing Applications Project
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Impact of Hydrologic
Changes on Wildlife Habitat
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Evaluating Wetland
and Estuarine Health
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Studies of Ocean
Internal Waves
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Studies of Local
Sea Level Change
Remote sensing provides large-scale synoptic observations
needed for global and regional investigations of land ecosystems, oceans,
and the atmosphere. By observing the reflection and emission of visible,
infrared and radar signals from wetlands,estuaries and coastal waters,
we can obtain valuable information about the coastal environment and resources.
To interpret the satellite and aircraft data accurately, mathematical and
physical models (algorithms) must be developed and validated. Our research
group is developing such models and using remotely sensed data with Geographic
Information System (GIS) to better understand coastal processes and ecosystems.
At the same time, we are providing information needed by coastal managers
for decision-making.
Remote Sensing of Wetland Biomass Changes
The biomass of estuarine wetland vegetation, an important
indicator of functional health, is sensitive to perturbations such as land
use changes and sea level rise. Our research team has developed algorithms
that use satellite data to estimate the biomass of the dominant salt marsh
plant Spartina alterniflora. A particularly relevant result is a unique method for remotely sensing wetland changes using biomass as an indicator. To detect biomass changes we use the Modified Soil Adjusted Vegetation Index (MSAVI) with red and near-infrared reflectances derived from Landsat/TM images. This biomass algorithm is applied to a time series of Landsat/TM images and used with selected thresholds to detect wetland changes. To minimize natural variations between images in the time series (e.g. atmospheric, annual, seasonal, etc.) we assume that the relative distribution of biomass in each sub-basin will remain essentially constant over time. Wetland pixels whose MSAVI deviation from the sub-basin mean changes from its previous deviation by more than a selected threshold value are considered as having changed. Threshold selection determines whether many small changes or only the more significant ones are detected. To minimize data costs, only changed sites flagged by Landsat/TM are studied in more detail with high-resolution systems, such as IKONOS or airborne scanners.
NOAA/NERRS Remote Sensing Applications Project
The NOAA National Estuarine Research Reserve System (NERRS) Program has selected several NERRS sites, including the Delaware's St. Jones River and Blackbird Creek Sites, for evaluation of airborne and satellite sensors for monitoring and mapping emergent wetlands and submerged aquatic vegetation. As part of this Remote Sensing Application Assessment Project (RESAAP), our team is investigating the cost-effectiveness of several remote sensing techniques, including airborne hyperspectral, airborne digital multispectral, high-resolution (e.g. IKONOS) and medium resolution (e.g. Landsat/TM) satellite imagery for observing health related properties of wetlands and estuaries. Wetland losses, biomass changes, invasive species, riparian buffers and other key environmental indicators are being studied and mapped.
Impact of Hydrologic Changes on Wildlife Habitat
We are studying major hydrologic and vegetative changes at the Milford Neck Wildlife Conservation Area, caused by a breach in the Grecos Canal barrier beach which occured during a storm in 1985. Due to the breach, the tidal regime in the area has changed dramatically, causing open water and mudflat areas to grow in some locations, and lagoons to fill in and develop low marsh vegetation in others. The results of this study are being used by state environmental managers and other wildlife managers to decide what action to take in order to optimize conditions for wildlife habitat, including migratory birds, shorebirds in general, etc. The Nature Society and Wildlands, Inc. are the other two groups involved.
Evaluating Wetland and Estuarine Health
The goal of this effort is to improve coastal management
by utilizing remotely sensed data in a GIS framework to evaluate land-use
and environmental indicators that are important for monitoring and managing
wetland and estuarine health. Our experience mapping the biomass of large
Spartina marshes showed that spectral reflectance signature variations
can be related to changes in Spartina biomass induced by stress. Our approach
optimizes data acquisition and processing for effective decision-making,
i.e., only those stress or environmental indicators that can be obtained
effectively by remote sensing and that are required to solve specific problems
and make management decisions are measured and processed. In a GIS, we
are able to store and manipulate data having different scales and time
periods, enabling us to investigate complex spatial and temporal relationships.
This study should help decision makers formulate appropriate responses
by relating wetland and estuarine health changes to land-use changes and
key environmental factors.
Studies of Ocean Internal Waves
Space shuttle and satellite SAR images provide an excellent view of high-contrast
ocean features such as internal waves, fronts, eddies, and oil slicks. Since ocean
internal waves generate local currents which modulate surface wavelets
and slicks, we have been able to detect packets of internal waves in space
shuttle photographs and radar imagery of the Atlantic, Pacific, and Indian
Oceans, and the Arabian Sea. Digitally orthorectified images are used to
derive statistics of internal waves on the continental shelf and for dynamic
analysis of internal waves in the deep ocean. The non-linear behavior of internal waves in the South China Sea is being studied using satellite and field data. To make this information available
to other investigators we have developed a global database on ocean internal
waves. The database includes visible and radar imagery, is supported by
ONR and NASA, and is accessible on the Internet.
Studies of Local Sea Level Change
The intent of this research is to examine the use of the
scrub/shrub-emergent wetland ecotone or transition community as an indicator
of local relative sea level change in the Delaware coastal landscape over
the last several decades. The proposed research will document the existence
and positional change in the scrub-shrub/emergent wetland ectone from aerial
photographs using photogrammetric techniques and geographical information
systems. It will determine the rate of positional change of this ecotone
and compare these movements to relative sea level changes as recorded by
tide gauges. The research then will relate the ecotone movements to natural
and human factors presumed to influence local relative sea level change.
Contributions of the research include the provision of a tangible,
low-cost landscape indicator of local relative sea level change, the reduction
of some uncertainty regarding the impacts of local relative sea level change
within the Delaware landscape, and the quantitative description of the
effect of human factors which influence local relative sea levels.
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Dr.
Vic Klemas
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Professor
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Co-Director, Center for Remote Sensing
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E-mail: klemas@udel.edu
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Dr. Richard T. Field
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Research Associate
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Ph.D. Students:
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Zhongxiang Zhao, Research Assistant, Ocean Internal Waves
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M.S. Students:
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Betsy Archer,Research Assistant, Coastal Manangement and
GIS
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to the Center for Remote Sensing Page.
Last modified: November 10, 2004
Brian Dzwonkowski---briandz@newark.cms.udel.edu