Radarsat-1 and ERS InSAR Analysis Over Southeastern Coastal Louisiana: Implications for Mapping Water-Level Changes Beneath Swamp Forests

Lü, Zhong; Kwoun, O.

doi:10.1109/tgrs.2008.917271

Cited by 130 publications

(91 citation statements)

References 40 publications

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“…Recent research has demonstrated the use of repeat-pass InSAR technology to monitor water level changes in a variety of wetlands, including tropical wetlands in the Amazon, hardwood swamps in Louisiana and the mangroves and sawgrass marshes of the Everglades [10][11][12][13][14]. Suitable coherence has been observed at X-, C-and L-band frequencies, although the maintenance of coherence during the temporal data acquisition period is critical to this methodology.…”

Section: Introductionmentioning

confidence: 99%

Seasonal Change in Wetland Coherence as an Aid to Wetland Monitoring

Brisco¹,

Ahern²,

Murnaghan³

et al. 2017

Remote Sensing

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Abstract:Water is an essential natural resource, and information about surface water conditions can support a wide variety of applications, including urban planning, agronomy, hydrology, electrical power generation, disaster relief, ecology and preservation of natural areas. Synthetic Aperture Radar (SAR) is recognized as an important source of data for monitoring surface water, especially under inclement weather conditions, and is used operationally for flood mapping applications. The canopy penetration capability of the microwaves also allows for mapping of flooded vegetation as a result of enhanced backscatter from what is generally believed to be a double-bounce scattering mechanism between the water and emergent vegetation. Recent investigations have shown that, under certain conditions, the SAR response signal from flooded vegetation may remain coherent during repeat satellite over-passes, which can be exploited for interferometric SAR (InSAR) measurements to estimate changes in water levels and water topography. InSAR results also suggest that coherence change detection (CCD) might be applied to wetland monitoring applications. This study examines wetland vegetation characteristics that lead to coherence in RADARSAT-2 InSAR data of an area in eastern Canada with many small wetlands, and determines the annual variation in the coherence of these wetlands using multi-temporal radar data. The results for a three-year period demonstrate that most swamps and marshes maintain coherence throughout the ice-/snow-free time period for the 24-day repeat cycle of RADARSAT-2. However, open water areas without emergent aquatic vegetation generally do not have suitable coherence for CCD or InSAR water level estimation. We have found that wetlands with tree cover exhibit the highest coherence and the least variance; wetlands with herbaceous cover exhibit high coherence, but also high variability of coherence; and wetlands with shrub cover exhibit high coherence, but variability intermediate between treed and herbaceous wetlands. From this knowledge, we have developed a novel image product that combines information about the magnitude of coherence and its variability with radar brightness (backscatter intensity). This product clearly displays the multitude of small wetlands over a wide area. With an interpretation key we have also developed, it is possible to distinguish different wetland types and assess year-to-year changes. In the next few years, satellite SAR systems, such as the European Sentinel and the Canadian RADARSAT Constellation Mission (RCM), will provide rapid revisit capabilities and standard data collection modes, enhancing the operational application of SAR data for assessing wetland conditions and monitoring water levels using InSAR techniques.

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Section: Introductionmentioning

confidence: 99%

Seasonal Change in Wetland Coherence as an Aid to Wetland Monitoring

Brisco¹,

Ahern²,

Murnaghan³

et al. 2017

Remote Sensing

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“…Thus we present Radarsat-1, which has a shorter wavelength interferograms, over the Chenier plain and ALOS interferograms over the Mississippi River delta. Previous studies indicate that the coherence of wetland interferograms is very sensitive to the temporal and perpendicular baselines (e.g., [11,13]). However, the temporal baseline contribution varies depending on the sensor and wetland types.…”

Section: Resultsmentioning

confidence: 99%

“…Several studies showed that the technique works well in woody wetlands [11,13]. Only few studies applied the technique to study water level changes in coastal areas.…”

Section: Introductionmentioning

confidence: 99%

InSAR-Based Mapping of Tidal Inundation Extent and Amplitude in Louisiana Coastal Wetlands

Oliver-Cabrera

Wdowinski

2016

Remote Sensing

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Abstract:The Louisiana coast is among the most productive coastal areas in the US and home to the largest coastal wetland area in the nation. However, Louisiana coastal wetlands have been disappearing at an alarming rate due to natural and anthropogenic processes, including sea level rise, land subsidence and infrastructure development. Wetland loss occurs mainly along the tidal zone, which varies in width and morphology along the Louisiana shoreline. In this study, we use Interferometric Synthetic Aperture Radar (InSAR) observations to detect the extent of the tidal inundation zone and evaluate the interaction between tidal currents and coastal wetlands. Our data consist of ALOS and Radarsat-1 observations acquired between 2006-2011 and 2003-2008, respectively. Interferometric processing of the data provides detailed maps of water level changes in the tidal zone, which are validated using sea level data from a tide gauge station. Our results indicate vertical tidal changes up to 30 cm and horizontal tidal flow limited to 5-15 km from open waters. The results also show that the tidal inundation is disrupted by various man-made structures, such as canals and roads, which change the natural tidal flow interaction with the coast.

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“…This sensitivity originates from the subsurface conditions and from the interferometric characteristics of SAR. Previous studies have shown that volume or surface scattering from reed marshes and other wetland types yields low coherence but that when doublebounce scattering dominates the return signal it becomes sufficiently coherent (Lu and Kwoun 2008). In fact, the hydrological state of reed marshes mainly reflects changes in the backscattering power and scattering mechanism.…”

Section: Discussionmentioning

confidence: 99%

A method for monitoring hydrological conditions beneath herbaceous wetlands using multi-temporal ALOS PALSAR coherence data

Zhang

Tian

et al. 2015

Int. Arch. Photogramm. Remote Sens. Spatial Inf. Sci.

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ABSTRACT:Reed marshes, the world's most widespread type of wetland vegetation, are undergoing major changes as a result of climate changes and human activities. The presence or absence of water in reed marshes has a significant impact on the whole ecosystem and remains a key indicator to identify the effective area of a wetland and help estimate the degree of degeneration. Past studies have demonstrated the use of interferometric synthetic aperture radar (InSAR) to map water-level changes for flooded reeds. However, the identification of the different hydrological states of reed marshes is often poorly understood. The analysis given in this paper shows that L-band interferometric coherence is very sensitive to the water surface conditions beneath reed marshes and so can be used as classifier. A method based on a statistical analysis of the coherence distributions for wet and dry reeds using InSAR pairs was, therefore, investigated in this study. The experimental results were validated by in-situ data and showed very good agreement. This is the first time that information about the water cover under herbaceous wetlands has been derived using interferometric coherence values. This method can also effectively and easily be applied to monitor the hydrological conditions beneath other herbaceous wetlands.

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Radarsat-1 and ERS InSAR Analysis Over Southeastern Coastal Louisiana: Implications for Mapping Water-Level Changes Beneath Swamp Forests

Cited by 130 publications

References 40 publications

Seasonal Change in Wetland Coherence as an Aid to Wetland Monitoring

Seasonal Change in Wetland Coherence as an Aid to Wetland Monitoring

InSAR-Based Mapping of Tidal Inundation Extent and Amplitude in Louisiana Coastal Wetlands

A method for monitoring hydrological conditions beneath herbaceous wetlands using multi-temporal ALOS PALSAR coherence data

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