Abstract:
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.
