A Remote Sensing Approach to Improve Desertification Monitoring and Assessment

Rainer Sandau
German Aerospace Center (DLR)
Rainer.sandau@dlr.de

Abstract

The United Nations Convention to Combat Desertification (UNCCD) reinforces the need for rigorous scientific knowledge and systematic monitoring of desertification. It also recognizes the importance of providing decision makers, in affected countries, with effective means to combat the problem, including relevant data, information and access to technology.
Space-aided technologies, which offer the unique advantages of transcending political boundaries, can provide a global coverage of the Earth; completing terrestrial observations and measurements and enhancing and complementing existing earth-based technology.
Despite the efforts of many countries and companies to promote the use of space borne remote sensing technology and despite the development of sensors optimized for specific tasks, e. g. forest fire, atmosphere, ozone, water quality, fishery, sea temperature, ice coverage; we notify that most of these sensors were and are still developed to be used in countries with “European” conditions (Important vegetation coverage; large landscape and land use units; soil albedo neglectable); one task is still missing - desertification. So, actually and at the exception of Spot-Vegetation or Landsat Thematic Mapper, these commercial sensors are not automatically suitable for desertification measurements; since in desertified areas, we deal with less vegetation coverage (rarely exceeding 30 %) and small land use units (mainly ranging from 0.5 to 1.0 hectare). Also, in desertified areas, the albedo is at its maximum with only small exceptions (oases, protected areas).
Developing cost-effective Earth observation missions is now within the means of many nations or regions. The development of small satellite technologies bears with it enormous opportunities to do more with less, address local and global needs, focus the development of the technical infrastructure of a country, and reduce risk inherent in the use of space. It is time now to think about an innovative, realistic and feasible contribution to the global fight against desertification, which makes optimum use of the relationships between space aided observation technology and the complex ecological and environmental systems in areas affected by desertification. A set of requirements in terms of spectral wavelengths, related ground resolutions and time related conditions needs to be derived to define a sensor system or a sensor suite which allows to monitor the desertification process and to provide the decision makers with effective information based on this newly available technology. As an example of the systematic of such an approach to define a sensor system for a specific task, the performance parameters of the DLR microsatellite BIRD (Bispectral Infrared Detection) are explained in the context of small temperature difference resolution.

The intention of this paper is to support the process of interdisciplinary thinking about new sensor systems and measurement methods and their implementation in order to solve problems connected to desertification.