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Oregon State University (1989)

Soil erosion assessment in the Republic of Cape Verde, West Africa, using a geographic information system

Gomez, Sharon N

Titre : Soil erosion assessment in the Republic of Cape Verde, West Africa, using a geographic information system

Auteur : Gomez, Sharon N

Université de soutenance : Oregon State University

Grade : Master of Science 1989

Résumé
Soil erosion is a natural physical process. However it can become a detrimental force when factors such as infertile soils, steep topography and poor farming practices are combined. An important initial aspect of resource planning and/or soil conservation involves locating areas where such potentially hazardous combinations occur in the field. This study proposes the development of a soil erosion hazard map for a watershed in the Cape Verde islands, West Africa. The Cape Verde archipelago is composed of volcanic islands that constitute the western extreme of the Sahel. They provide classic examples of those areas where combinations of certain environmental factors result in cases of severe sheet, nil and gully erosion. A range of computer software and theoretical modelling was used to develop a soil erosion hazard map for a 110 sq.km. watershed on the main island of Santiago. The programs included a computer cartography programme (Aut0CAD), a Digital Elevation Modelling program (SURFER) and a Geographic Information System - GIS (IDRISI). The research provided a study of the independent variables that impact soil erosion and their interactions. It also illustrated several concepts of automated environmental modelling and mapping : for instance data entry ; vector-raster, raster-vector conversions ; data analysis using a GIS and data output. The final map indicated that most of the watershed was susceptible to low-moderate risk erosion. And the rest of the land posed a moderate-high or severe risk erosion. More importantly, the map will allow planners to gain an insight into the location of areas that require attention for conservation measures in the watershed.

Mots clés : Soil erosion — Cape Verde - -Land use — Geographic information systems

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