<div class="csl-bib-body">
<div class="csl-entry">Schlaffer, S., McKenna, O., & Dorigo, W. A. (2022, May 25). <i>Dynamics of open water and vegetated wetlands extent from Sentinel-1 dual-polarised data in a prairie catchment in North Dakota</i> [Poster Presentation]. ESA Living Planet Symposium 2022, Bonn, Germany. http://hdl.handle.net/20.500.12708/153718</div>
</div>
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dc.identifier.uri
http://hdl.handle.net/20.500.12708/153718
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dc.description.abstract
The wetlands in the Prairie Pothole Region (PPR) are of critical importance as habitat and breeding grounds for the North American waterfowl population. Like many wetlands, they are threatened by climate change and intensifying agriculture. Monitoring these wetlands is therefore an important source of information for landscape management. Pothole wetlands range in size from a few square metres to several square kilometres. Larger wetlands covered by open water surfaces can be monitored using optical or radar satellite imagery. Smaller wetlands (< ca. 1 ha) are more challenging to delineate due to the moderate spatial resolution of most satellite sensors (typically in the range of a few tens of metres) and due to vegetation frequently emerging from the water surface of shallow water bodies. However, these small wetlands have been shown to be of high importance as habitats as well as linkages between larger wetlands, thus contributing to hydrological and biological connectivity. Radar imagery has been used for detecting water underneath vegetation based on double-bounce scattering leading to high radar returns, however, this effect is highly dependent on factors, such as wavelength, polarisation, incidence angle and vegetation density and height relative to the water surface. Hence, information gathered in situ is often required to constrain retrieval models.
In this study, Sentinel-1 dual-polarised synthetic aperture radar (SAR) time series acquired between 2015 and 2021 are used in combination with water level measurements from a number of permanent and temporary wetlands in North Dakota. The study period covers hydrometeorological conditions ranging from drought to flooding. A Bayesian framework is applied to integrate high-resolution topographic data to constrain water delineation in areas with low contrast. Dual-polarised SAR backscatter from open and vegetated wetlands is compared with in-situ water level measurements.
The results for open water bodies show that small and large wetlands differ in seasonality as well as in their response to wet and dry years. While large water bodies are mostly stable throughout the year, many small water bodies fall dry during the summer months, when evaporation exceeds moisture supply. During wet periods, prairie hydrological processes, such as merging between neighbouring wetlands, can be observed. The effects of drought years, such as the exceptionally dry year 2021, are visible across wetland size classes, however, larger wetlands (> ca. 8 ha) tend to be more stable than smaller ones. First results of the comparison between backscatter and water level generally show an increase of co-polarised (VV) backscatter in temporary wetlands with falling water levels, whereas the cross-polarised (VH) signal tends to be more stable. This is in line with our expectations as double-bounce scattering mainly affects the co-polarised radar signal. The results demonstrate the potential of dual-polarised Sentinel-1 image time series for high-resolution monitoring of prairie wetlands. Limitations of this study are related to wind inhibiting correct open water extent retrieval and due to the rather long acquisition interval of 12 days over the PPR, which is a result of the observation strategy of Sentinel-1.
en
dc.language.iso
en
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dc.subject
Wetlands
en
dc.subject
Synthetic Aperture Radar (SAR)
en
dc.subject
Hydrology
en
dc.title
Dynamics of open water and vegetated wetlands extent from Sentinel-1 dual-polarised data in a prairie catchment in North Dakota
en
dc.type
Presentation
en
dc.type
Vortrag
de
dc.contributor.affiliation
United States Geological Survey, United States of America (the)
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dc.type.category
Poster Presentation
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tuw.researchTopic.id
E4
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tuw.researchTopic.name
Environmental Monitoring and Climate Adaptation
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tuw.researchTopic.value
100
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tuw.publication.orgunit
E120 - Department für Geodäsie und Geoinformation
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tuw.author.orcid
0000-0003-4742-8648
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tuw.author.orcid
0000-0001-8054-7572
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tuw.event.name
ESA Living Planet Symposium 2022
en
tuw.event.startdate
23-05-2022
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tuw.event.enddate
27-05-2022
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tuw.event.online
Hybrid
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tuw.event.type
Event for scientific audience
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tuw.event.place
Bonn
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tuw.event.country
DE
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tuw.event.institution
ESA
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tuw.event.presenter
Schlaffer, Stefan
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wb.sciencebranch
Geodäsie, Vermessungswesen
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wb.sciencebranch
Informatik
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wb.sciencebranch
Hydrologie
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wb.sciencebranch.oefos
2074
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wb.sciencebranch.oefos
1020
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wb.sciencebranch.oefos
1053
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wb.sciencebranch.value
45
-
wb.sciencebranch.value
15
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wb.sciencebranch.value
40
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item.cerifentitytype
Publications
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item.fulltext
no Fulltext
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item.openairetype
conference poster not in proceedings
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item.languageiso639-1
en
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item.openairecristype
http://purl.org/coar/resource_type/c_18co
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item.grantfulltext
none
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crisitem.author.dept
E120 - Department für Geodäsie und Geoinformation
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crisitem.author.dept
United States Geological Survey
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crisitem.author.dept
E120-08 - Forschungsbereich Klima- und Umweltfernerkundung
