REMOTE SENSING EVALUATION OF URBAN ENCROACHMENT ON THE DENSU 
DELTA AND SAKUMO WETLANDS OF ACCRA/TEMA MUNICIPAL AREAS, GHANA. 
Sosthenes Kwadzo Kufogbe 
G.T. Agyepong, J.K. Amatekpor, P.W.K. Yankson 
University of Ghana 
Department of Geography and Resource Development 
P.O.Box 59, Legon Accra, Ghana 
ABSTRACT 
The coastal wetlands of Ghana particularly those in the Accra-Tema Metropolitan Area 
appear to be under threat of encroachment from urban areas. Time sequential aerial 
photographs (1970 - 1986) and geometrically corrected digital Landsat TM data (1985 - 1991) 
are being investigated as bases for assesing the nature and extent of the phenomenon and also 
as a first stage in the compilation of wetland resource inventory. Principal Component Analysis 
was used to reduce the digital Landsat TM data to 3 bands. Broad spectral classes were 
identified in a preliminary Box classification procedure to provide training areas which were 
later adopted in the Maximum Likelihood procedure. The use of Global Positioning System 
(GPS) permited reasonably accurate correlation of field and image data. Results of the 
preliminary survey suggest that expansion in built up areas comprising mainly residential and 
industrial buildings and agricultural activities constitute the most significant threat to the 
stability of the wetland ecosystems. TM Band 5 was particularly useful for distinguishing the 
immediate environment of the wetland from other contiguous land use/cover classes. Owing to 
problems of spectral separability of classes, it is suggested that the interpretation of large scale 
aerial photographs on scale 1:10,000 would provide much more accurate basis for generating 
data to be incorporated into plans for development of the wetlands into proposed Ramsar 
sites. 
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