The study focuses on the characteristics of the Modder River in the Free State. The
Modder River plays an important role in supplying water for domestic, agricultural and
industrial uses in the Bloemfontein, Botshabelo and Thaba Nchu areas. According to
present (2001) estimates by the Centre of Environmental Management of the University of
the Free State, the Modder River is exploited to its full capacity owing to the construction
of dams.
As the name of river suggests, the Modder River is said to have high sediment loads. In
Afrikaans, modder means mud. The drainage pattern of the Modder River reveals well-developed
dendritic drainage on the eastern part of the catchment and an endoreic
drainage pattern on the western part.
This study aims to evaluate the spatial variability of sediment sources along the main
course of the Modder River as well as assess the possible role of fluvial geomorphology in
river management. The study is based on the hypothesis that the high sediment load in the
Modder River main course is caused more by riverbank processes than by the surface of
the basin. Helicopter and fieldwork surveys were carried out in order to obtain the required
materials (variables). The spatial variability of bank-forming material, vegetation cover,
type and channel form were investigated in order to realise the aim of this study.
The channel form of the Modder River indicates a decrease in sediment loads since the
channel form shows some shrinkage immediately below the Krugersdrift Dam. The
Modder River transports less and less sediments downstream as a result of a high number
of constructed dams. Dams are barriers that create discontinuities in the channel system.
Observations of the characteristics of the banks of the Modder River reveal that these
banks are resistant to erosion owing to the luxuriant vegetation growth and low stream
power because of the channel gradient. A question arises as to whether the Modder River really has such high sediment loads as
its name suggests. Given the current state of the Modder River, high sediments are highly
localised at certain sections of the stream. The transfer of sediments from one part of the
river to another depends on the availability of sediment sources in space and time.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ufs/oai:etd.uovs.ac.za:etd-11102005-082835 |
| Date | 10 November 2005 |
| Creators | Tsokeli, Raboroko David |
| Contributors | Dr CH Barker |
| Publisher | University of the Free State |
| Source Sets | South African National ETD Portal |
| Language | en-uk |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.uovs.ac.za//theses/available/etd-11102005-082835/restricted/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University Free State or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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