| Titre | Comparing Landsat and RADARSAT for current and historical dynamic flood mapping |
| Auteur | Olthof, I; Tolszczuk-Leclerc, S |
| Source | Remote Sensing vol. 10, issue 5, 780, 2018 p. 1-19, https://doi.org/10.3390/rs10050780  Accès ouvert |
| Image |  |
| Année | 2018 |
| Séries alt. | Ressources naturelles Canada, Contribution externe 20190179 |
| Éditeur | MDPI AG |
| Document | publication en série |
| Lang. | anglais |
| DOI | https://doi.org/10.3390/rs10050780 |
| Media | en ligne; numérique |
| Formats | pdf (Adobe® Reader®); html |
| Programme | Science de la télédétection spatiale, Caractérisation de la surface terrestre |
| Diffusé | 2018 05 18 |
| Résumé | (disponible en anglais seulement)
Mapping the historical occurrence of flood water in time and space provides information that can be used to help mitigate damage from future flood events. In
Canada, flood mapping has been performed mainly from RADARSAT imagery in near real-time to enhance situational awareness during an emergency, and more recently from Landsat to examine historical surface water dynamics from the mid-1980s to present.
Here, we seek to integrate the two data sources for both operational and historical flood mapping. A main challenge of a multi-sensor approach is ensuring consistency between surface water mapped from sensors that fundamentally interact with the
target differently, particularly in areas of flooded vegetation. In addition, automation of workflows that previously relied on manual interpretation is increasingly needed due to large data volumes contained within satellite image archives. Despite
differences between data received from both sensors, common approaches to surface water and flooded vegetation mapping including multi-channel classification and region growing can be applied with sensor-specific adaptations for each. Historical open
water maps from 202 Landsat scenes spanning the years 1985-2016 generated previously were enhanced to improve flooded vegetation mapping along the Saint John River in New Brunswick, Canada. Open water and flooded vegetation maps were created over the
same region from 181 RADARSAT 1 and 2 scenes acquired between 2003-2016. Comparisons of maps from different sensors and hydrometric data were performed to examine consistency and robustness of products derived from different sensors. Simulations
reveal that the methodology used to map open water from dual-pol RADARSAT 2 is insensitive to up to about 20% training error. Landsat depicts open water inundation well, while flooded vegetation can be reliably mapped in leaf-off conditions. RADARSAT
mapped approximately 8% less open water area than Landsat and 0.5% more flooded vegetation, while the combined area of open water and flooded vegetation agreed to within 0.2% between sensors. Derived historical products depicting inundation frequency
and trends were also generated from each sensor's time-series of surface water maps and compared. |
| Sommaire | (Résumé en langage clair et simple, non publié)
Les services géomatiques d'urgence (EGS) s'appuient sur l'imagerie de plusieurs satellites aux spécifications différentes pour fournir des
données en temps utile lors d'une situation d'urgence, comme une inondation. L'EGS doit s'assurer que les informations générées par les différentes sources de données satellitaires sont cohérentes, afin que les changements entre des images
consécutives soient liés à la progression réelle de l'inondation ou aux changements de situation sur le terrain, et non à des sources de données différentes. En outre, une cartographie historique des inondations est nécessaire à la fois pour générer
des cartes des inondations en temps quasi réel et pour que la Sécurité publique puisse évaluer les risques d'inondation sur la base des événements passés. Ce document compare les cartes des inondations provenant de deux principaux satellites utilisés
pendant les inondations, l'un optique (Landsat) et l'autre canadien (RadarSat). Environ 200 cartes d'inondation historiques sont générées à partir des données de chaque capteur. Les cartes des inondations coïncidentes sont comparées entre elles et à
la profondeur des inondations à partir des jauges d'eau. Les cartes des inondations historiques, y compris l'étendue maximale des inondations dérivées de chaque source de données, sont également comparées. |
| GEOSCAN ID | 315345 |
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