Monitoring of gully systems by large-scale aerial photographic surveys

• Aerial surveys with hot-air blimp and kite as platforms for photographic and digital 35 mm SLR cameras
• Digital image processing and GIS analysis for 2D documentation of gully systems
• Digital photogrammetric processing of stereo photographs for 3D documentation of gully systems
• Analysis and interpretation of monitoring series for quantification of gully development

Development of Gully Gorom (Burkina Faso) between July 2000 and December 2001; multitemporal GIS analysis.

Investigation of gully catchment area and surrounding regions

• Geomorphological mapping of gully headcut environments
• Substrate analysis (textur, aggregate stability, solubles)
• Mapping of types and distribution of soil crusts
• Land use mapping of gully catchments based on aerial photographs and field studies
• Assessment of distribution and role of gullies in the region based on satellite imagery

Measurement programmes on infiltration and runoff generation

• Infiltration measurements for assessment of infiltration capacity in gully catchment
• Rainfall simulation for assessment of runoff and soil erosion
• Flushing experiments for measurement of debonding rate by dispersion and of transport capacity in dessication cracks and animal holes in headcut vicinity

Graph of infiltration capacity on fallow land in the Ebro Basin, with and without soil crusts.

Aerial photography (left), topographical map by stereoscopic analysis (centre) and 3D TIN model (right) of Gully Oursi, Province of Oudalan (Burkina Faso), December 2001. The airphoto covers an area of 18 x 35 m over the upper branch of a gully cutting into a Pleistocene dune of aeolian deposits in Burkina Faso's Sahel zone. Stereoscopic mapping of gully scarps and contour lines reveals a complex dendritic system with different levels of incision, overhanging walls and bridges. Volume quantification from the TIN model amounts to a soil loss of 214 m³, affecting an area of 234 m² which was eroded in less than 8 years.