Hydroclimatic trends, sediment sources and geomorphic response in the Bell River catchment, eastern Cape Drakensberg, South Africa

Dollar, Evan Stephen John and Rowntree, Kate (1995) Hydroclimatic trends, sediment sources and geomorphic response in the Bell River catchment, eastern Cape Drakensberg, South Africa. South African Geographical Journal, 77 (1). pp. 21-32. ISSN 0373-6245

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Abstract

The Bell River in the Eastern Cape Drakensberg of South Africa has shown recent signs of channel instability as evidenced by avulsion, sinuosity reductions, gradient steepening and general channel instability. Analysis of rainfall data did not provide evidence for progressive long term change in rainfall pattern for the catchment. However, annual and seasonal rainfall cycles with variance peaks every 16-19 years were found, from which it can be inferred that flood events following years of below average rainfall may cross the threshold limit for channel stability. Channel instability is often followed by a major flood event after sustained low rainfall periods, a sequence referred to as the Flood and Drought Dominated Regimes by Warner (1987). Evidence presented also indicates an increase in catchment erosion in the past century with attendant sediment production increases to the channel. This may be due to catchment land use and management practices (following settlement by commercial farmers) superimposed on long term climatic changes. The conclusions are that catchment and channel processes are inseparable, and that disequilibrium in the catchment will be transferred to the channel.

Item Type:Article
Uncontrolled Keywords:anthropogenic impact; catchment erosion; channel instability; flood; hydroclimatic trend; sediment; land use; meteorology; rivers; land use changes; rainfall trends; flow variability; sediment sources; soil erosion mapping; ground surveys; gully erosion; temporal changes; erosion initiation; catchment management; South Africa, Eastern Cape Province, Drakensberg, Bell River; river basin catchments; climate; geomorphology; hydrology; sediment
Subjects:Y Unknown > Subjects to be assigned
Divisions:Faculty > Faculty of Science > Geography
ID Code:527
Deposited By:INVALID USER
Deposited On:05 Mar 2007
Last Modified:01 Aug 2012 08:03
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