| Titre | Seasonal Change in Wetland Coherence as an Aid to Wetland Monitoring |
| Auteur | Brisco, B; Ahern, F; Murnaghan, K; White, L; Lancaster, P |
| Source | Remote Sensing of Environment vol. 9, no. 158, 2017., https://doi.org/10.3390/rs9020158  Accès ouvert |
| Image |  |
| Année | 2017 |
| Séries alt. | Secteur des sciences de la Terre, Contribution externe 20130057 |
| Éditeur | MDPI AG |
| Document | publication en série |
| Lang. | anglais |
| DOI | https://doi.org/10.3390/rs9020158 |
| Media | papier; en ligne; numérique |
| Formats | pdf |
| Province | Ontario |
| SNRC | 31G/05 |
| Région | Ottawa valley |
| Lat/Long OENS | -76.0000 -75.5000 45.5000 45.2500 |
| Sujets | imagerie radar; géoradar; méthodes radar; imagerie par satellite; satellite LANDSAT; satellites; inondations; potentiel d'inondation; terres humides; marais; sols; végétation; détection de changements;
géologie de l'environnement; hydrogéologie |
| Illustrations | images Landsat; cartes de localisation; tableaux; graphiques |
| Programme | Science de la télédétection spatiale, Caractérisation de la surface terrestre |
| Diffusé | 2017 02 15 |
| Résumé | (disponible en anglais seulement)
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. |
| Sommaire | (Résumé en langage clair et simple, non publié)
Les données sur les eaux de surface peuvent soutenir un certain nombre d'applications, notamment en hydrologie, en météorologie, en écologie et
en agronomie. De grandes quantités d'eau sont essentielles à la santé des milieux humides. L'imagerie satellite de radar à synthèse d'ouverture (RSO) représente une importante source de données pour la surveillance des eaux de surface,
particulièrement dans des conditions météorologiques difficiles. Dans le présent article, nous évaluons des méthodes permettant de déterminer si RADARSAT2, le satellite RSO du Canada, peut servir à la surveillance des niveaux d'eau dans les zones
humides. Les résultats indiquent que la cohérence (le degré de coïncidence des surfaces mesuré selon une échelle de 0 [faible] à 1 [élevé]) est prometteuse comme outil de surveillance pour signaler les changements dans les milieux humides. Ainsi, il
est alors possible de déterminer la cause de ces changements et d'y remédier. Dans notre article, nous indiquons les recherches supplémentaires qui seront nécessaires à la mise en 'uvre opérationnelle de cette technologie dans le cadre de futures
missions de satellites RSO (par ex. la Constellation RADARSAT mission). |
| GEOSCAN ID | 292590 |
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