An assessment of scale issues related to the configuration of the ACRU model for design flood estimation
MetadataShow full item record
There is a frequent need for estimates of design floods by hydrologists and engineers for the design of hydraulic structures. There are various techniques for estimating these design floods which are dependent largely on the availability of data. The two main approaches to design flood estimation are categorised as methods based on the analysis of floods and those based on rainfall-runoff relationships. Amongst the methods based on the analysis of floods, regional flood frequency analysis is seen as a reliable and robust method and is the recommended approach. Design event models are commonly used for design flood estimation in rainfall-runoff based analyses. However, these have several simplifying assumptions which are important in design flood estimation. A continuous simulation approach to design flood estimation has many advantages and overcomes many of the limitations of the design event approach. A major concern with continuous simulation using a hydrological model is the scale at which should take place. According to Martina (2004) the “level” of representation that will preserve the “physical chain” of the hydrological processes, both in terms of scale of representation and level of description of the physical parameters for the modelling process, is a critical question to be addressed. The objectives of this study were to review the literature on different approaches commonly used in South Africa and internationally for design flood estimation and, based on the literature, assess the potential for the use of a continuous simulation approach to design flood estimation. Objectives of both case studies undertaken in this research were to determine the optimum levels of catchment discretisation, optimum levels of soil and land cover information required and, to assess the optimum use of daily rainfall stations for the configuration of the ACRU agrohydrological model when used as a continuous simulation model for design flood estimation. The last objective was to compare design flood estimates from flows simulated by the ACRU model with design flood estimates obtained from observed data. Results obtained for selected quaternary catchments in the Thukela Catchment and Lions River catchment indicated that modelling at the level of hydrological response units (HRU’s), using area weighted soils information and more than one driver rainfall station where possible, produced the most realistic results when comparing observed and simulated streamflows. Design flood estimates from simulated flows compared reasonably well with design flood estimates obtained from observed data only for QC59 and QCU20B.
Showing items related by title, author, creator and subject.
Runoff simulation using the SWAT model for flood frequency analysis and design flood estimations in the Luvuvhu River catchment, South Africa. Thavhana, Mulalo Precious. (2018)Abstract available in PDF file.
Botes, Zacheus Adriaan. (2014)The current state of flood modelling relies on statistical techniques revolving around either river or rainfall data that are used to produce an estimated flood return period (e.g. 1:100 year). These tend to ignore 1) the ...
Perceptions of the impacts of artificial flood releases on the general use of the natural resources of the Pongolo River floodplain, South Africa. Salagae, Modukanele Alloycius. (2007)A social survey of the communities living adjacent to the Pongolo river floodplain was carried out, in order to understand the perceptions of the impact of artificial flood releases on the general use of natural resources ...