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Satellite Imagery of Flooding Along the Richelieu River: CSA-NASA Partnership

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May 2011

Satellite Imagery of Flooding Along the
Richelieu River: CSA-NASA Partnership

Within the framework of the international Committee on Satellite Earth Observation (CEOS), the Canadian Space Agency (CSA) is collaborating with NASA on various projects helping to prevent, manage and respond to natural disasters. This partnership offers the opportunity for CSA and NASA to share Earth Observation (EO) data acquired by several Canadian and American satellites for scientific and operational purposes. These including the development of models, systems and procedures geared toward flood forecasting and response. During the flood event along the Richelieu areas (Quebec, Canada) in May 2011, CSA asked colleagues from NASA to acquire satellite images with the EO-1/ALI sensor (Earth Observation-1/Advanced Land Imager) in order to capture the flood in its entirety. These images complement RADARSAT-2 images acquired by the Canadian Government over the past weeks over the affected region, providing additional detail thanks to the multi-spectral and pan-chromatic imaging capabilities of ALI. In combination with RADARSAT-2 images acquired at the peak of the flood, NASA's ALI images will give the opportunity to monitor the spatial extent of the flooded areas and assist authorities on the ground with their flood response measures.

This animation of three satellite images shows the recent flood situation along the Richelieu River in Quebec on May 8, 2011. The first two are natural colour and infra-red images acquired by NASA's EO-1/ALI, or Advanced Land Imager, at a spatial reolution of 10 and 30 meters, respectively. The third one is a radar image was acquired by the Canadian RADARSAT-2 at a resolution of 25 meters. All three images cover the same area: the northernmost portion of Lake Champlain, the severely flooded banks of the Richelieu River, as well as settlements, agricultural landscapes and towns along its course, such as Saint-Paul-de-l'Ile-aux-Noix, Saint-Jean-sur-Richelieu and Chambly. Both ALI and RADARSAT imagery show the extent of the flood along the river very well in dark blue and in black image tones, respectively. The multispectral ALI imagery clearly reveals various types of vegetation and land cover; for example active vegetation growth is depicted in bright green on the infra-red image, and mostly bare or sparsely covered ground surfaces are revealed in shades of pink and beige colours. Clouds and cloud shadows are noticeable in some portions of the ALI imagery. Radar offers the advantage of cloud-penetration and therefore more reliable imaging capabilities. In addition to the very dark water surfaces, the RADARSAT-2 image clearly reveals many buildings and settlement areas in contrasting bright image tone ("corner reflections"); bright image tone is also indicative of flooded vegetation in the Richelieu River flood plain and some wetlands along Lake Champlain.

Contacts:
Guy Séguin (ASC, CEOS/Disaster SBA Lead)
Stuart Frye (NASA, CSDP 1/Lead)
Guy Aubé (ASC, CSDP 2/Lead)