Researchers and civic officials in Africa will soon have access to near-real-time information on the height of rivers and lakes, thanks to the European Space Agency's Envisat program. Envisat is turning out to be one of the most significant ecological information projects ever; the "River-Lake" project is just the latest in a series of investigations of the global environment from orbit. Envisat is providing data for hurricane intensity forecasts, monitoring phytoplankton blooms, mapping atmospheric pollution, helping to coordinate aid efforts in Darfur, even assembling the sharpest and most detailed photograph ever of the Earth's surface.
The Envisat River-Lake project is intended to assist with water management planning, as well as supporting efforts to prevent water-born illnesses such as malaria and cholera. The satellite uses a radar altimeter (similar to those used to map Mars and Venus) for surface measurements. As the system approaches its ultimate goal of 3-hour turnaround for the data, the River-Lake project may also have significant value as a monitor of flooding or storm surges.
The River-Lake project wasn't actually an original goal of the Envisat, but is a new application of the satellite sensors:
The effort to develop the River and Lake product was led by Professor Philippa Berry of DMU's Earth and Planetary Remote Sensing Laboratory: "Monitoring of water resources is vital over Africa, to enable best use of this precious commodity. Until now reliable information has been difficult to access because of the high cost in equipment, manpower and communications, and because it is difficult to obtain these precious hydrological data from many countries.
"However heights of inland water can now be measured directly from space using radar altimeters, currently carried on several satellites and originally designed to measure ocean height. This is a very exciting development which has the potential to transform the management of drought crises and water-related conflict around the world."
Envisat uses a radar altimeter to fire 1800 radar pulses every second at the surface of the Earth, measuring with extreme precision the time taken to receive the radar echo. The current system, which is still in testing, is able to deliver measurements within three days; when it comes online, designers intend for the response time to be down to under six hours, with an ultimate goal of under three hours. But while the system is moving towards very rapid response, the ESA is also planning for the long-term: the project will spend the next ten years gathering baseline data on river and lake systems around the world. The River-Lake project is currently focused on Africa, but will soon be extended to Canada and Latin America.
It seems like this is a very useful instrument. Brazil is experiencing some of the lowest water levels in the Amazon ever, endangering transport of goods and people. They could use the capacities of Envisat.
Same story for the mighty Congo, which works in similar cycles as the Amazon, and which is a major logistical route for Central-Africa.
By the way, today ESA launches the long awaited Cryosat: http://www.esa.int/SPECIALS/Cryosat/index.html