Eric MASSON, TVES EA 4477 -Université de Lille / Polytech Lille, France
In January 2021, the alluvial plain of the middle Garonne was heavily affected by winter floods. This hydrological event was recorded by various hydrological and satellite sensors allowing near-real-time access to information on water level, runoff value and flooding area. Nine Sentinel 1A/B images were acquired between January 20th and February 7th 2021 and were made available in near-real time on the European Space Agency platform. During this period, Marmande's water gauge recorded the water levels every 5 minutes. These data was made available in real time on the vigiecrue website and have served as a source of information and alerts and early warning for local and regional authorities, as well as for riverine population. Finally, since 2021, the National Institute of Geographic and Forestry Information has made public topographic data at 1m spatial resolution for the entire country. These three opensource datasets not only allow the monitoring of flooding events but also the estimation of water heights and stored water volumes at any point of the Garonne's floodplain. Moreover, these data can also be processed with opensource softwares and dedicated toolboxes such as QGIS (OSGEO) or SNAP (ESA).
Our contribution will demonstrate how open source data and geospatial tools allow for near-real-time hydrologic monitoring providing with reliable informations for alerts, early warning and floodmapping in the case of slow downstream progression of inundations.
Mots clés : Alert|Early warning|near-real-time|Vigicrues|Sentinnel 1A/B
A105317EM