Advice, methods and tools for estimating channel roughness

Advice, methods and tools for estimating channel roughness.
McGahey , C.and Knight, D. and Samuels, P.G.
Proceedings of the Institution of Civil Engineers - Water Management, 162 . (2009)

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Abstract:Roughness plays an essential role in water level estimation for rivers, watercourses and drains. It reduces the discharge capacity through energy expenditure from boundary-generated turbulence as well as physical blockages caused by vegetation. Today's practitioners are constantly challenged with identifying, quantifying and simulating these processes to provide vital information for a range of flood risk management tasks. This paper introduces the roughness advisor, one of a series of tools embedded in the recently developed Environment Agency's conveyance and afflux estimation system. The roughness advisor provides an extensive database of roughness information from a diverse set of sources (>700) and presents it in a structured manner to enable users readily to select from a range of in-channel and floodplain vegetation and bed material types. Traditionally, flow resistance datasets are based on average values of Manning's n for whole river sections. Here, the notion of a local unit roughness n(l) is introduced and its performance is demonstrated through flow prediction for a range of channel types. Further applications are used to compare the unit roughness with the traditional Manning n, to trial a boulder roughness approach and to describe the sensitivity and relative importance of roughness in the calculation of channel flow.
Item Type:Article
Subjects:Floods > River management
Floods > General
ID Code:453
Deposited On:29 Nov 2010 13:04
Last Modified:21 Aug 2014 08:56

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