Remote sensing

A tool to monitor and assess desertification

Issue 2 44 pp. • Published in December 2005

Author(s): Begni Gérard, Escadafal Richard, Fontannaz Delphine, Hong-Nga Nguyen Anne-Thérèse

Remote sensing is a technique that enables to observe the radiation scattered or emitted by the Earth surface. Satellite-based remote sensing allows regular, repetitive, accurate observations of nearly the whole planet, at various spatial and temporal scales, in several wavelength fields.

Such observations render the nature, state, temporal and spatial variations of the properties of the objects at the Earth surface. By way of example, water-covered areas, roughness, soil moisture, changes in the nature of land, density and phenological evolution of the vegetation cover, sand winds, are information included in these observations. Nevertheless, these observations usually combine together, making them more or less difficult to extract from the raw data transmitted by satellites. The science of remote sensing consists in interpreting and processing the series of spatial and temporal images in order to extract such parameters, qualitatively or quantitatively. Desertification is a phenomenon of irreversible land degradation. It results from complex processes linked to the coupled and joint evolution of natural and human-induced factors. The beginning, development and results of such processes are materialised by land surface states and their evolution.

Remotely sensed data consequently include information that the science of remote sensing allows to partly extract with more or less accuracy. Such information coupled with others are involved in various stages of the desertification process. Remote sensing provides useful data; some of them are essential information impossible to collect otherwise (especially in terms of homogeneity and spatial coverage and/or temporal monitoring) for early warning, monitoring the development of desertification phenomena and acknowledging a final state. Among others, remote sensing may allow to determine the impacts of policies to combat desertification. However, because of the mentioned limits regarding the extraction of useful parameters and the part played by the latter in the processes concerned, remote sensing turns out to be a tool among others - certainly a powerful one, but not a scientific, decisional or operational “miracle” solution.

After presenting in detail the technique and science of remote sensing and how it allows to monitor various elements of desertification processes, this brochure deals with the most important and significant cases and brings both aspects together. Several key parameters and processes are studied: roughness, albedo, surface temperature, moisture, vegetation indices on the one hand; vegetation cover monitoring, modifications in the land surface composition in dry environments, wind transportation on the other hand. Examples are developed: evolutions of specific sites, projects under way. Lessons taught by previous experiments are critically analysed, options for the future are designed.

    Begni Gérard

    Begni Gérard

    CNES; Earth Environnement & Climate – Senior Scientist

    Escadafal Richard

    Escadafal Richard

    Chair of CSFD. Senior scientist IRD at CESBIO, Toulouse (France)

    Fontannaz Delphine

    Fontannaz Delphine

    Research Engineer at Médias-France

    Hong-Nga Nguyen Anne-Thérèse

    Hong-Nga Nguyen Anne-Thérèse

    Research Engineer at Médias-France


    La télédétection

    Dossier du CSFD 2  •  2005

    La télédétection

    Un outil pour le suivi et l’évaluation de la désertification

Support

Editing, production and distribution of Les dossiers thématiques du CSFD are fully supported by this Committee thanks to the support of relevant French Ministries and AFD (French Development Agency).

  • Ministère de l’Enseignement supérieur et de la Recherche
  • Ministère des Affaires étrangères
  • Ministère de l’Écologie, du Développement durable et de l’Énergie
  • Agence Française de Développement (AFD)

Opinions

The opinions expressed in these reports are endorsed by the Committee.

Contact

CSFD
Comité Scientifique Français de la Désertification
Agropolis International
1000 avenue Agropolis
F-34394 Montpellier CEDEX 5 •  France
Tel.: +33 (0)4 67 04 75 44 • email: csfd@agropolis.fr




Comité Scientifique Français de la Désertification

CSFD
Agropolis International
1000 avenue Agropolis
F-34394 Montpellier CEDEX 5 •  France
Tel.: +33 (0)4 67 04 75 44 • email: csfd@agropolis.fr

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Website: Olivier Piau (Agropolis Productions)
© 2013 Comité Scientifique Français de la Désertification (CSFD)

Dossiers

thématiques du CSFD

Mankind is now confronted with an issue of worldwide concern, i.e. desertification, which is both a natural phenomenon and a process induced by human activities. Our planet and natural ecosystems have never been so degraded by our presence. Long considered as a local problem, desertification is now a global issue of concern to all of us, including scientists, decision makers, citizens from both developed and developing countries. Within this setting, it is urgent to boost the awareness of civil society to convince it to get involved. People must first be given the elements necessary to better understand the desertification phenomenon and the concerns. Everyone should have access to relevant scientific knowledge in a readily understandable language and format.

Within this scope, the French Scientific Committee on Desertification (CSFD) has decided to launch a series entitled Les dossiers thématiques du CSFD, which is designed to provide sound scientific information on desertification, its implications and stakes. This series is intended for policy makers and advisers from developed and developing countries, in addition to the general public and scientific journalists involved in development and the environment. It also aims at providing teachers, trainers and trainees with additional information on various associated disciplinary fields. Lastly, it endeavours to help disseminate knowledge on the combat against desertification, land degradation, and poverty to stakeholders such as representatives of professional, nongovernmental, and international solidarity organisations.

These Dossiers are devoted to different themes such as global public goods, remote sensing, wind erosion, agroecology, pastoralism, etc, in order to take stock of current knowledge on these various subjects. The goal is also to outline debates around new ideas and concepts, including controversial issues; to expound widely used methodologies and results derived from a number of projects; and lastly to supply operational and academic references, addresses and useful websites. These Dossiers are to be broadly circulated, especially within the countries most affected by desertification, by email, through our website, and in print. Your feedback and suggestions will be much appreciated!

Scientific editing and iconography: Isabelle Amsallem, Agropolis Productions
Design and production: Olivier Piau, Agropolis Productions