African water authorities receive space-tool training

ESA’s TIGER Initiative was launched in 2002 following the World Summit on Sustainable Development in Johannesburg. The primary objective of TIGER is to help African countries overcome problems faced in the collection, analysis and dissemination of water related geo-information by exploiting Earth Observation technology.

Freshwater is a scarce commodity across much of Africa and is projected to grow scarcer still. The continent's share of global freshwater is only 9% – a static resource in an ever-thirstier world. Availability of freshwater is important not just for drinking and sanitation but also to ensure food security – 60% of African food production comes from non-irrigated agriculture, leaving it vulnerable to climatic variations.

Researchers from Ethiopia, Cameroon, Kenya, Ivory Coast, Namibia, Morocco, Madagascar, Botswana and South Africa representing selected African universities, research centres and public administrations involved with ongoing TIGER research projects are learning how to incorporate Synthetic Aperture Radar (SAR) image processing into their projects.

The SAR instrument onboard ESA’s ERS satellites and the Advanced Synthetic Aperture Radar (ASAR) onboard ESA’s Envisat satellite use radar to map the surface of the planet below, with several different modes that allow broad views or detailed snapshots. It is able to work day and night and penetrate clouds and bad weather to map the shape of the land, profile waves and ice, monitor land use and types of vegetation and measure some of the properties of the surface.

Topics being addressed at the training session include SAR principles and processing techniques, microwave techniques for hydrological applications, soil moisture estimation, flood mapping, vegetation monitoring and the fusion of SAR images and optical images.

Prof. Paolo Ferrazzoli of the University of Tor Vergata is one of the key lecturers and is teaching the trainees some basic physics in order to better understand the content of SAR images, such as the variables for water-related applications.

“The information content of microwaves is different than optical information content, so by complimenting these two different information sources, we improve our capability to monitor all aspects related to water such as soil moisture, vegetation and wetlands,” Ferrazzoli said.

The trainees all come from different regions of Africa and face specific water-related issues. For example, Madagascar’s Fanja Vololona Razafindramasy of the University of Antananarivo wants to incorporate radar data into her study of erosion.

According to the World Bank for Madagascar, the country has a ‘world-record erosion rate’, which is a serious problem for a country whose economy relies on agricultural production. The erosion is filling and clogging coastal waterways with sediment, which has resulted in some port facilities having to be moved inland to prevent ships running aground. By using SAR, it is possible to identify changes in land surface related to severe erosion process.

Freshwater is a limited natural resource in South Africa, which receives only around half the average rainfall of other countries. Water availability is heavily dependent on climate, water use and management and land-use practices. The country’s National Water Act of 1998 is based on the principles of sustainability of use and equity of water distribution.

South Africa’s Willem Vorster from the Satellite Applications Centre (CSIR) said: “We are working with the Department of Water Affairs to help them monitor the new National Water Act that is starting to be implemented nationally. We want to see if we can monitor the effectiveness of this Act by using radar images.”

One of the major development resources facing Morocco is the sustainable management of its water. According to the United Nations, in 2000 58 percent of the rural population lacked access to adequate sanitation, and 42 percent lacked access to drinking water. Some two-thirds of Morocco’s agricultural exports are produced by irrigated agriculture and consume 92 percent of the country’s freshwater resources.

Dr. Ahmed Er Raji of the Centre Royal de Teledetection Spatiale in Morocco is training to use ASAR to help local authorities find more water resources for drinking, to monitor the extension of agricultural exploitation and to detect the vulnerable zones regarding excessive damping of ground water.

“When I return to Morocco we are planning to organise a training session with our partners and colleagues so I can share this information with them,” Er Raji said.

Since the initiation of TIGER more than 150 African organisations – including water and basin authorities, technical centres, universities and regional organisations – have become involved in different projects around the continent.