| dc.description.abstract | Northeastern Ghana, West Africa, is characterised by a high population growth rate and adverse
climatic conditions, e.g., a long dry season followed by a short-duration but intense rainfall
pattern. Land degradation in this part of the country has caused farmers to extend their
agricultural activities into marginal lands including flood plains. The consequence is an increase
in flood damage to cropland, livestock, infrastructure and human lives. In this study, the nature
of vegetation change in the Tamne River Basin was assessed by integrating remote sensing and
geographic information systems (GIS). Inter-annual variation in rainfall and streamflow were
assessed using statistical hypothesis testing. Gumbel Extreme Value distribution was used to
estimate peak flow magnitudes for selected return periods. Field observations and interviews
with farmers provided first hand information about the farming systems in the Tamne River
Basin. There was no significant change inter-annual variation in rainfall and hydrologic response
and the estimated 100 year peak flow was 59.9 m3/s. Less than one percent of the total area in
Tamne River Basin changed between 1975 and 1991. The distribution of the potential land cover
changes confirmed the assertion that, farming systems constitute a primary cause of land
degradation in the Upper East Region. The potential land cover changes have little or no effect
on the hydrologic response in the Tamne River Basin. The study also provided a broad
framework for detailed watershed analysis at the basin and sub-basin level, including the
monitoring of land use change and distributed hydrologic modelling. In addition, the study
highlighted some o f the problems related to incomplete and outdated environmental information,
and their implications on the effective integration of remote sensing and GIS for resource
management and policy formulation in Ghana. Suggestions have been made for: integration of
‘expert systems’ into GIS and image processing in Ghana; quantitative accuracy assessment for
the potential land cover changes; and, event-based hydrologic modelling for sub-catchments in
the Tamne River Basin. | |
