Title: Farm dam siltation and sediment source tracing in the Zeerust Swartruggens area in the north-west of South Africa

Authors: Samuel Che Nde; Munyaradzi Manjoro; Manny Mathuthu

Addresses: Department of Geography and Environmental Sciences, North-West University, Mafikeng Campus, Private Bag X2046, Mmabatho 2735, South Africa ' Department of Geography and Environmental Sciences, North-West University, Mafikeng Campus, Private Bag X2046, Mmabatho 2735, South Africa ' Centre for Applied Radiation Science and Technology (CARST), North-West University, Mafikeng Campus, Private Bag X2046, Mmabatho 2735, South Africa

Abstract: Soil erosion and dam siltation are two serious environmental problems facing farmers in South Africa. The study aimed to assess farmers' perceptions on dam siltation and strategies employed to address it, and to assess the potential of sediment source tracing in a farming area in the north-west region of South Africa. Most of the dams in the study area were severely affected by siltation and the most important strategy used to address the problem was regular mechanical removal of the accumulated sediment. In relation to sediment tracing, lead-210 (210Pb) was found to be a more effective tracer than caesium-137 (137Cs) for distinguishing between surface and subsurface sediment sources. On the other hand, magnetic susceptibility offered better distinction of the sediment sources than magnetic remanence. Mass balance modelling indicated that 100% of the sampled sediment dam 1 originated from surface sources. The results reflect the complexity of sediment mobilisation processes influenced by the nature and spatial distribution of rainfall and runoff connectivity in the catchments.

Keywords: farm dam siltation; environmental radionuclides; environmental magnetism; sediment source tracing; mass balance modelling.

DOI: 10.1504/IJHST.2019.102322

International Journal of Hydrology Science and Technology, 2019 Vol.9 No.3, pp.324 - 337

Received: 04 Feb 2017
Accepted: 17 Nov 2017

Published online: 13 Sep 2019 *

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