EROSION AND SEDIMENT YIELD IN RELATION TO AFFORESTATION AND FIRE IN THE MOUNTAINS OF THE WESTERN CAPE PROVINCE, SOUTH AFRICA
Open Access
- 1 April 1998
- journal article
- research article
- Published by Taylor & Francis in South African Geographical Journal
- Vol. 80 (1), 52-59
- https://doi.org/10.1080/03736245.1998.9713644
Abstract
The mountains of the Western Cape Province fulfil a vital water supply function in the region. For the protection of this water supply, it is important to understand natural soil erosion rates in these mountains and human influence on these. The main land management practices are prescribed burning of natural vegetation for conservation of bio-diversity and water yield, and the use of mountain land for the production of timber from plantations of exotic tree species. Wildfires are an inherent risk during the dry summers. This paper reports various studies at different scales a over 20 year period with most estimates of erosion being indirect, through measurement of sediment in streams. Small increases in sediment yields have been measured following prescribed burning of catchments which are covered in fynbos, the natural sclerophyllous scrub vegetation of the region. The bulk of sediment is carried in stormflows, and individual storms may dominate the annual sediment yield. Soil losses per unit area off small mid-slope plots are much higher than those measured at the catchment level, and estimated erosion rates are inversely proportional to the size of the erosion plot. Riparian zones appear to be important in keeping sediment delivery ratios low. High intensity wildfires in the late dry season have the potential to cause large increases in stormflow and sediment yields in burned catchments. This is particularly the case in timber plantations where fuel loads are higher and may be concentrated in slash piles, and where road systems may aid the transport of surface runoff. Marked hydrological responses to wildfire have been associated with fire-induced water repellency in the soils of the burned catchments.Keywords
This publication has 18 references indexed in Scilit:
- The hydrological effects of fire in South African mountain catchmentsJournal of Hydrology, 1993
- Sediment sources and sediment transport by rill flow and interrill flow on a semi-arid piedmont slope, southern ArizonaCATENA, 1993
- The Hydrological Effects of a Wildfire in a Eucalypt Afforested CatchmentSouth African Forestry Journal, 1992
- The effects of wildfire on soil wettability and hydrological behaviour of an afforested catchmentJournal of Hydrology, 1990
- Impact of timber harvesting and production on streams: A reviewMarine and Freshwater Research, 1989
- EFFECT OF FIRE ON HYDROPHOBIC AND CEMENTING SUBSTANCES OF SOIL AGGREGATES1Soil Science, 1983
- Sediment Control in South African Forests and Mountain CatchmentsSouth African Forestry Journal, 1980
- The Effect of Hydrophobic Substances on Water Movement in Soil during InfiltrationSoil Science Society of America Journal, 1971
- Soil Slips Related to Vegetation, Topography, and Soil in Southern CaliforniaWater Resources Research, 1969
- Resistance to Wetting in the Surface of Sandy Soils Under Citrus Trees in Central Florida and Its Effect Upon Penetration and the Efficiency of IrrigationSoil Science Society of America Journal, 1947