Changes in shape and water shedding potential of three landforms on a vertisol in Ghana

Abstract

This study was carried out to investigate the effect of time on the physical changes and water shedding potential of three landforms established on the Vertisols in a coastal savanna zone of Ghana. Observations showed that crest height of the Flat Beds (FB) changed only minimally from an initial value of 0.09 m to 0.07 m after two years and to a final value of 0.069 m after five years. The observation suggests that the FB stabilized very quickly and remained un-changed once constructed. However, the crest height of the Broad Bed and Furrow (BBF) decreased from an initial value of 0.194 m to 0.163 m after the first two years of construction and further to 0.149 m after five years. In the case of the Cambered Bed and Furrow (CBF), crest height decreased from 0.39 m to 0.35 m after two years and further to 0.30 m after five years of formation. Accompanying the changes in crest height were also changes in land sur-face  configuration. In both BBF and CBF, there was significant reduction in concavity of the crest-to-crest configuration after the first two years of construction but there were no signifi-cant changes thereafter. Ageing therefore affected the water shedding potential of the various land forms. Both the FB and CBF had a reduction of 15 % in water shedding capability after 5 years of construction, while the reduction was 12 % in the case of BBF.