15 Jul Remote sensing in disaster management
Natural disasters place humanity at nature’s mercy. Thanks to technologies in use by SANSA’s Earth Observation team, we have the ability to mitigate their effects.
Technologies like Remote Sensing and Geographic Information Systems allow SANSA to monitor disasters such as drought, Earthquakes, tsunamis, volcanic eruptions, field fires and floods. Satellite images are used to identify vulnerable areas, evacuation routes and suitable locations for warning systems. Optical remote sensing, which uses visible, short-wave infrared sensors to create images of the Earth, contributes to search and rescue operations in areas inaccessible by road. Radar data is useful during oil spills and floods, as it’s not affected by atmospheric interference and cloud cover.
RADAR detects objects in the atmosphere using radio waves, and determines their speed, direction and altitude.
In January this year, floods hit the rural town of Matatiele in the Eastern Cape. Satellite images were used by SANSA to identify flooded areas and houses which were built within the flood risk zone. Of the 87 houses built within 100m of the Matatiele River, 12 were at great risk of being flooded. This kind of information is essential in planning settlements to prevent damages and loss of life.
Earth observation has long been important to monitoring floods after they happen. SANSA is now working with the SA Weather Service to anticipate floods before they happen. “It’s fairly easy to look at the damage done after a flood,” says EO Directorate MD Jane Olwoch. But by working with meteorologists to understand when and where the rain is going to fall, and superimposing data on hydrology, land use, and historic rain and flood patterns, SANSA will build a national map of areas which are more disaster-prone. “Then we can advise the authorities that ‘this is a flood area, so don’t build roads and houses here,'” says Olwoch.
By anticipating floods, SANSA makes planning much easier for provincial and local disaster management and emergency services.
SANSA is also working closely with the National Disaster Management Centre to ensure a model is developed to identify areas at risk of being flooded. The SERVIR-CREST hydrological model will simulate variations of land surface and subsurface water in specific areas over specific periods of time. It will identify areas likely to be flooded by analysing rainfall and potential evapotranspiration data, a digital elevation model (DEM), river discharge and soil.
Evapotranspiration is the amount of plant transpiration and water evaporation from land and ocean surfaces released into the atmosphere.
SANSA is also a project manager in the International Charter on Space and Major Disasters. SANSA co-ordinates remote sensing data from other space agencies in response to natural disasters in the SADC region. Even archived information about past disasters is instrumental in gaining a better understanding of trends and dynamics which contribute to natural disasters.