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Development of a customised design flood estimation tool to estimate floods in gauged and ungauged catchments

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dc.contributor.advisor AJOL: Water SA
dc.contributor.author Gericke, O.J.
dc.contributor.author du Plessis, J.A.
dc.date.accessioned 2016-02-01T13:05:35Z
dc.date.available 2016-02-01T13:05:35Z
dc.date.issued 2013
dc.date.issued 2013
dc.identifier.issn 03784738
dc.identifier.issn 18167950
dc.identifier.uri http://hdl.handle.net/11462/712
dc.description Published Article en_US
dc.description.abstract The estimation of design flood events, i.e., floods characterised by a specific magnitude-frequency relationship, at a particular site in a specific region is necessary for the planning, design and operation of hydraulic structures. Both the occurrence and frequency of flood events, along with the uncertainty involved in the estimation thereof, contribute to the practising engineers’ dilemma to make a single, justifiable decision based on the results obtained from the plethora of ‘outdated’ design flood estimation methods available in South Africa. The objectives of this study were: (i) to review the methods currently used for design flood estimation in South Africa for single-site analysis, (ii) to develop a customised, user-friendly Design Flood Estimation Tool (DFET) containing the latest design rainfall information and recognised estimation methods used in South African flood hydrology, and (iii) to demonstrate the use and functionality of the developed DFET by comparing and assessing the performance of the various design flood estimation methods in gauged catchments with areas ranging from 100 km² to 10 000 km² in the C5 secondary drainage region, South Africa. The results showed that the developed DFET will provide designers with an easy-to-use software tool for the rapid estimation and evaluation of alternative design flood estimation methods currently available in South Africa for applications at a site-specific scale in both gauged/ungauged and small/large catchments. In applying the developed DFET to gauged catchments, the simplified ‘small catchment’ (A ≤ 15 km²) deterministic flood estimation methods provided acceptable results when compared to the probabilistic analyses applicable to all of the catchment sizes and return periods, except for the 2-year return period. Less acceptable results were demonstrated by the ‘medium catchment’ (15 km² < A ≤ 5 000 km²) deterministic and ‘large catchment’ (>5 000 km²) empirical flood estimation methods. It can be concluded that there is no single design flood estimation method that is superior to all other methods used to address the wide variety of flood magnitude-frequency problems that are encountered in practice. Practising engineers’ still have to apply their own experience and knowledge to these particular problems until the gap between flood research and practice in South Africa is narrowed by improving existing (outdated) design flood estimation methods and/or evaluating methods used internationally and developing new methods for application in South Africa. en_US
dc.format.extent 1 433 303 bytes, 1 file
dc.format.mimetype Application/PDF
dc.language.iso en_US en_US
dc.publisher AJOL: Water SA
dc.relation.ispartofseries Water SA;Vol 39, No 1
dc.subject Design flood en_US
dc.subject design rainfall en_US
dc.subject estimation en_US
dc.subject ungauged catchments en_US
dc.subject flood magnitude-frequency en_US
dc.title Development of a customised design flood estimation tool to estimate floods in gauged and ungauged catchments en_US
dc.type Article en_US
dc.rights.holder Water SA

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