Potential applications

Prevention, crisis and post-crisis response:
a three-sided problem

The impacts of floods, forest fires, earthquakes and other natural disasters around the globe in recent years are forcing us to seek new prevention and mitigation methods. This task involves developing predictive models and monitoring tools, drawing up regulatory requirements and planning emergency response.

For this purpose, we need to acquire regularly updated, reliable and objective spatially referenced information in timely fashion.



The only way to prevent flooding is through effective land-use planning and a detailed knowledge of land occupancy and the natural phenomena likely to affect a region. In this respect, high- and very-high-resolution Earth observation data are a valuable aid for producing and maintaining maps to provide information about flood-prone areas.

Understanding the phenomenon
SPOT 5 has the potential to improve our understanding of land use, land cover and flood extents. Investigations covering an area of the Ried central d'Alsace, a marshy floodplain in north-east France, used SPOT 5 data to identify natural and man-made features that have helped to stem historical floods. These include:

Man-made and natural features limiting flood extent in the Erbesmunster region of the lower Rhine valley, France.

 

Assisting risk prevention planning
SPOT 5 2.5-metre black-and-white data, which allow analysis at a scale of 1:5 000, are a cost-effective solution that usefully complements traditional surveying methods relying on aerial photography.
At this scale, SPOT 5 data can be combined with cadastral maps for flood risk prevention planning. Flood prevention plans define parcel-level guidelines that serve as a basis for establishing regulatory land-use provisions and awarding building permits.

 

 


Optical and radar satellite imagery has already shown its potential for detecting damage caused by natural disasters. However, earthquake damage chiefly affects buildings and until now it has proven impossible to interpret damage zones in sufficient detail with the level of spatial resolution currently available for civil applications. SPOT 5's improved resolution and capabilities will make it possible to map earthquake damage quickly.











Supporting emergency response
On the morning of 26 January 2001, an earthquake registering 7.7 on the Richter Scale hit the region of Kachchh in Gujarat, north-west India. The United States Geographical Survey located the epicentre of the tremor, the most destructive in India for 50 years, some 20 kilometres north-east of the town of Bhuj.

Investigations were conducted in this region to demonstrate how SPOT 5 data can assist emergency management and disaster response teams in urban areas. This project aimed to map urban zones affected by the earthquake by comparing two satellite images-one acquired before and one immediately after the event-within less than 48 hours of image reception and with little or no additional information to aid interpretation.

 


The method is based on locating damage by automatic processing, followed by a vital photointerpretation step. Results show that SPOT 5 is able to detect changes to large buildings and determine the probability that they have been damaged.
Automatic processing significantly speeds up photointerpretation and ensures that it is exhaustive. For a region such as Bhuj, covering 112 square kilometres, a single operator can complete photointerpretation within 48 hours.


The advantages of SPOT 5 for natural disaster management

HRG instrument (High Resolution Geometric)
Finer resolution for improved hazard mapping

- Finer ground resolution in black-and-white mode: 2.5 metres and 5 metres (instead of 10 metres).
- Finer resolution in colour mode: 10 metres (instead of 20 metres)
- Like all their predecessors, each SPOT 5 instrument covers a 60-kilometre swath.
- Oblique viewing makes it possible to revisit areas of interest frequently.
- Access to SPOT 5 archive imagery through on-line catalogue

HRS instrument (High Resolution Stereoscopic)
Digital elevation models for hazard modelling

- SPOT 5's dedicated HRS instrument provides stereoscopic imaging capability along the satellite track.
- Panchromatic band offers spatial resolution of 10 metres.
- Imaging swath centred on the satellite ground track is 120 kilometres, and maximum scene length is 600 kilometres.
- Elevation accuracy of DEMs generated from HRS images
. Relative : 5 to 10 m
. Absolute : 10 to 15 m

 

References