Original Articles

RATE OF EROSION IN THE CATCHMENT OF THE BULBERGFONTEIN DAM NEAR REDDERSBURG IN THE ORANGE FREE STATE

DOI: 10.1080/03779688.1979.9633191
Author(s): J.S. Ie RouxDepartment of Geography, South Africa, Z.N. RoosDepartment of Geography, South Africa

Abstract

The volume of sediment in the Bulbergfontein Dam was computed after mapping the area of the dam and ascertaining the depth of the sediment by digging and augering. The watershed of the impoundment had been delimited by means of aerial photographs and field work. The catchment has a mean slope of 1,9° which is mostly covered by perennial grasses and xerophytic shrublets. Approximately 75 per cent of the area is natural pasture and the rest under maize and wheat cultivation. The mean annual rainfall is 471 mm. The fortuitous presence of a fine sand layer (marker) in the sediments made it possible to compute not only the total accumulation of sediment, but also the accumulation since 1971. From these figures the rates of erosion were found to be 27,5 mm 10−3 years for the period 1942 to 1971 and 34,6 mm 10−3 year for the period 1972 to 1978.

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