Revised regional sediment yield prediction methodology for ungauged catchments in South Africa

• Published in: Journal of the South African Institution of Civil Engineering 2017-06, Vol.59 (2), p.28-36
• Main Authors: Msadala, V, Basson, G
• Format: Article
• Language: English
• Subjects: Catchments; Civil engineering; Data analysis; Empirical analysis; Engineering, Civil; Probabilistic methods; Reservoir sedimentation; Sedimentation; Sedimentation & deposition; Sediments; Water resources
• ISSN: 1021-2019; 2309-8775; 2309-8775
• DOI: 10.17159/2309-8775/2017/v59n2a4

This paper presents the research on the revision of the regional probabilistic method (Rooseboom et al 1992) for the prediction of catchment sediment yields in South Africa. The determination of sediment yields using probabilistic or empirical methods is suitable for ungauged catchments in the absence of observed data. The prediction of sediment loads is a key component in the quest to deal with reservoir and river sedimentation which is a potential threat to the sustainability of water resources in southern Africa. The revision was necessitated by increased sediment data availability and improved data analysis tools. Ten new sediment yield regions were demarcated in South Africa and Lesotho. Two analytical approaches were developed, namely probabilistic and empirical. The probabilistic approach is applicable in sediment yield Regions 3, 6 and 9. The empirical approach is applicable in sediment yield Regions 1, 2, 4, 5, 7 and 8. The estimation of sediment yields in Region 10 (Lesotho Highlands) needs to be based on direct measurements and locally observed data since no adequate analysis of sediment loads was possible due to limited data. GIS and electronic portable document file (pdf) copies of maps were produced for the retrieval of catchment data.