The research project MoGul (Large-scale Monitoring of Gully Erosion in Semi-Arid Landscapes) investigates the various types, form development and dependencies of gullies as well as morphological processes involved in gullying at study areas following a transect from Northern Spain to West Africa.

Gullies are typical erosion forms in semi-arid and arid landscapes all over the world where high morphological activity and dynamics can be observed. Albeit low in rainfall amount, semi-arid climate conditions and precipitation regimes encourage gully erosion by irregular precipitation frequency and distribution and by frequent heavy rainfall events.

Gully erosion near Gorom-Gorom in the Sahel zone of Burkina Faso

Gullying between grazed abanonded fields at the slopes above the Negratín reservoir, Andalusia.

In addition, widespread land use changes of traditional agriculture towards more extensive use - often as sheep pasture - prepares the ground for reduced soil infiltration capacity and increased runoff, aggravating the risk of linear erosion downslope. The contribution of gullies to total soil loss by erosion is, however, much debated by erosion researchers: While some speak of spectacular but over-estimated erosion forms, others describe gullies as the most important sediments sources in dry-lands and emphasize the massive offsite impairment (e.g. reservoir siltation) caused by gullying.

Customary terrestric measurement methods as well as interpretation of conventional aerial photography does by no means comply with the high spatial and temporal dynamics of gully systems. Instead, large-scale multitemporal aerial photography taken from kites or hot-air blimps enables detailed documentation and monitoring of gully systems. Gully growth and loss of soil material are measurable to high precision with geographic information systems and digital photogrammetric analysis, thus allowing to quantify gully development in different climatic zones under various conditions of relief, runoff, substrate and land use.

The MoGul research group is headed by  Prof. Dr. Johannes B. Ries (Department of Physical Geography at Trier University) and Dr. Irene Marzolff (Department of Physical Geography at Frankfurt University) and complemented by diploma candidates and student assistants. There is close cooperation with Dr. Manuel Seeger (Department of Physical Geography at Trier University) and colleagues from the universities of Leuven (Belgium), Zaragoza (Spain) and Agadir (Morocco). This research study is funded by the Deutsche Forschungsgemeinschaft DFG under project number RI835/2-1.

The project and its research methods are documented in web filmlets (in German) which were produced for a master thesis at Trier University.

ALBERT, K.-D., MÜLLER, J., RIES, J. B. & MARZOLFF, I. (2004): Aktuelle Landdegradation in der Sahelzone (Burkina Faso). - In: Albert, K.D., Löhr, D. & Neumann K. (Hrsg.): Mensch und Natur in Westafrika. – Ergebnisse aus dem Sonderforschungsbereich "Kulturentwicklung und Sprachgeschichte im Naturraum Westafrikanische Savanne". Weinheim, pp. 289-330.

MARZOLFF, I., RIES, J. B. & ALBERT, K.-D. (2003): Kite aerial photography for gully monitoring in sahelian landscapes. Proceedings of the Second Workshop of the EARSeL Special Interest Group on Remote Sensing for Developing Countries, 18-20 September 2002, Bonn, Germany. (CD-ROM publication)

RIES, J. B. & MARZOLFF, I. (2003): Monitoring of gully erosion in the Central Ebro Basin by large scale aerial photography taken from a remotely controlled blimp. - Catena 50, 2-4, pp. 309-328.

MARZOLFF, I., ALBERT, K.-D. & RIES, J. B. (2002a): Fernerkundung vom Fesseldrachen. Luftbild-Monitoring gibt Aufschluss über Schluchterosion in der Sahelzone. – Forschung Frankfurt, 3/2002, pp. 16-22.

MARZOLFF, I., ALBERT, K.-D. & RIES, J. B. (2002b): Großmaßstäbiges Luftbildmonitoring in Trockenräumen der Erde – Gully-Erosion in der Sahelzone. – In: JUNGE, A. (Hrsg.): Geowissenschaften in Frankfurt. Kleine Senckenbergische Reihe 43, Frankfurt am Main.