Toggle Main Menu Toggle Search

Open Access padlockePrints

Estimating extreme flood magnitude in bedrock-influenced channels using representative reach-based channel resistance data

Lookup NU author(s): Professor Andy Large


Full text for this publication is not currently held within this repository. Alternative links are provided below where available.


Extreme flood events are considered by many researchers to be very important in controlling the development of semi-arid bedrock-influenced river systems. Accurate gauging of such events is often impossible, however, as gauges are drowned and often damaged during the event. A methodology for estimating flood discharge for bedrock-influenced channels is presented that reconstructs hydrometric characteristics of the peak flow and relates these to the roughness character of the river channel in question. The method is evaluated using peak water-surface slope data relating to the extreme floods of February 2000 along the Sabie and Letaba rivers, located respectively in the Mpumalanga and Northern Provinces, South Africa. The data, in the form of strandline measurements, were taken at hydraulically relevant points along the long profile of both rivers. The resultant data are utilised together with published high flow channel resistance figures, based on the channel morphology of the Sabie and Letaba rivers, to generate peak flow estimates for a number of locations along both rivers. Comparisons are made between the frictional discharge peak flow estimates, velocity-area and hydrologie estimates of peak flow. These comparisons indicate that the method can produce discharge estimates with an accuracy of ± 10% and ± 35% respectively.

Publication metadata

Author(s): Heritage G, Large ARG, Moon B, Birkhead A

Publication type: Article

Publication status: Published

Journal: Geografiska Annaler, Series A: Physical Geography

Year: 2003

Volume: 85

Issue: 1

Pages: 1-11

Print publication date: 01/01/2003

ISSN (print): 0435-3676

ISSN (electronic): 1468-0459


DOI: 10.1111/1468-0459.00184


Altmetrics provided by Altmetric