The effect of catchment land use on sediment input to Swartvlei

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dc.contributor.authorBarker, Janet Alexandraen_ZA
dc.date.accessioned2015-12-13T04:22:12Z
dc.date.available2015-12-13T04:22:12Z
dc.date.issued1985en_ZA
dc.descriptionBibliography: pages 239-249.en_ZA
dc.description.abstractThe littoral aquatic plant community of Swartvlei declined after 1978, apparently as a result of increased lake water turbidity. To investigate the causes of this, land use and land management of the Swartvlei catchment area have been studied. Possible causes and the extent of accelerated runoff and sediment loss in different rainfall conditions were determined. Rainfall, water flow, Secchi disc and sediment load data are reviewed and the apparent relationship between them noted. Water samples were collected at 32 different sample sites to determine sediment loads. Samples were vacuum filtered through coarse and fine glass fibre filters and the results recorded in milligrams of sediment per litre of water. The quantity and duration of rainfall in the immediate pre-sampling period were recorded. Secchi disc transparency of Swartvlei water was recorded. Catchment land use and land management are described in four areas based on land use and geographical location. The naturally vegetated montane upper catchment area, the foothill plantation area, the agricultural areas on the tertiary plateau and the road reconstruction and recreation areas are considered separately. Land use and land management information was obtained from a literature review and study of topographical maps, orthophotographs, geological survey maps and aerial photographs. Flights over the area enabled confirmation of observations. Informal interviews with persons involved in catchment management, property-owners and roads authorities were conducted. Areas of accelerated sediment loss were determined and the magnitude of the problem noted. Results show that rainfall duration, intensity, quantity and distribution determine the effect of sediment-laden runoff on river and vlei water quality. Small storm events (< 50 mm) influence the water quality of tributaries particularly in the lower catchment areas. Storm events of > 50 mm influence the main catchment rivers and light penetration in Swartvlei at the river inflow points. Long-duration flood rainfalls bring about massive soil loss in the catchment and cause reduced light penetration over the entire surface area of Swartvlei. Most sediment originates from the lower sections of the catchment area where human activities are most intense. Natural vegetation acts as a protective barrier against soil loss and its removal and the lack of suitable runoff channels leads to greater sediment loss. Recommendations to reduce sediment loss are made. The topographical and soil characteristics of the area make it sensitive to soil loss, the significance of which has only been recognised recently. The socio-economic circumstances in the region and the present economic recession are limiting amelioration of the situation in this beautiful natural area.en_ZA
dc.identifier.apacitationBarker, J. A. (1985). <i>The effect of catchment land use on sediment input to Swartvlei</i>. (Thesis). University of Cape Town ,Faculty of Science ,Department of Environmental and Geographical Science. Retrieved from http://hdl.handle.net/11427/15793en_ZA
dc.identifier.chicagocitationBarker, Janet Alexandra. <i>"The effect of catchment land use on sediment input to Swartvlei."</i> Thesis., University of Cape Town ,Faculty of Science ,Department of Environmental and Geographical Science, 1985. http://hdl.handle.net/11427/15793en_ZA
dc.identifier.citationBarker, J. 1985. The effect of catchment land use on sediment input to Swartvlei. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Barker, Janet Alexandra AB - The littoral aquatic plant community of Swartvlei declined after 1978, apparently as a result of increased lake water turbidity. To investigate the causes of this, land use and land management of the Swartvlei catchment area have been studied. Possible causes and the extent of accelerated runoff and sediment loss in different rainfall conditions were determined. Rainfall, water flow, Secchi disc and sediment load data are reviewed and the apparent relationship between them noted. Water samples were collected at 32 different sample sites to determine sediment loads. Samples were vacuum filtered through coarse and fine glass fibre filters and the results recorded in milligrams of sediment per litre of water. The quantity and duration of rainfall in the immediate pre-sampling period were recorded. Secchi disc transparency of Swartvlei water was recorded. Catchment land use and land management are described in four areas based on land use and geographical location. The naturally vegetated montane upper catchment area, the foothill plantation area, the agricultural areas on the tertiary plateau and the road reconstruction and recreation areas are considered separately. Land use and land management information was obtained from a literature review and study of topographical maps, orthophotographs, geological survey maps and aerial photographs. Flights over the area enabled confirmation of observations. Informal interviews with persons involved in catchment management, property-owners and roads authorities were conducted. Areas of accelerated sediment loss were determined and the magnitude of the problem noted. Results show that rainfall duration, intensity, quantity and distribution determine the effect of sediment-laden runoff on river and vlei water quality. Small storm events (< 50 mm) influence the water quality of tributaries particularly in the lower catchment areas. Storm events of > 50 mm influence the main catchment rivers and light penetration in Swartvlei at the river inflow points. Long-duration flood rainfalls bring about massive soil loss in the catchment and cause reduced light penetration over the entire surface area of Swartvlei. Most sediment originates from the lower sections of the catchment area where human activities are most intense. Natural vegetation acts as a protective barrier against soil loss and its removal and the lack of suitable runoff channels leads to greater sediment loss. Recommendations to reduce sediment loss are made. The topographical and soil characteristics of the area make it sensitive to soil loss, the significance of which has only been recognised recently. The socio-economic circumstances in the region and the present economic recession are limiting amelioration of the situation in this beautiful natural area. DA - 1985 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 1985 T1 - The effect of catchment land use on sediment input to Swartvlei TI - The effect of catchment land use on sediment input to Swartvlei UR - http://hdl.handle.net/11427/15793 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/15793
dc.identifier.vancouvercitationBarker JA. The effect of catchment land use on sediment input to Swartvlei. [Thesis]. University of Cape Town ,Faculty of Science ,Department of Environmental and Geographical Science, 1985 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/15793en_ZA
dc.language.isoengen_ZA
dc.publisher.departmentDepartment of Environmental and Geographical Scienceen_ZA
dc.publisher.facultyFaculty of Scienceen_ZA
dc.publisher.institutionUniversity of Cape Town
dc.subject.otherEnvironmental and Geographical Scienceen_ZA
dc.titleThe effect of catchment land use on sediment input to Swartvleien_ZA
dc.typeMaster Thesis
dc.type.qualificationlevelMasters
dc.type.qualificationnameMAen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceThesisen_ZA
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