Title
Factors affecting overland flow velocity in peatlands
Description
Overland flow is an important component of peatland hydrology. Hydrological models of peatlands are being developed that require estimates of flow velocity and its controls. However, surprisingly little is known about overland flow velocities in peatlands. Some peatlands have also been drained using open ditches, and these need to be incorporated into flow models. This paper presents field data on the velocity of overland flow and drain flow in upland peatlands. The relationships between flow velocity, vegetation cover, slope, and water depth are explored. Sphagnum provided a significantly greater effective hydraulic roughness to overland flow than peatland grasses. In all cases, a significant break in process occurred for flows with water depths of around 1 cm so that there were two components of the roughness curve. This is consistent with partial submergence theory for very shallow flows where resistance increases with depth as the soil surface first becomes fully submerged. While each surface cover type should be considered separately, the results also suggest that a first-order estimate of Darcy- Weisbach roughness and mean velocity can be based on a single parameter for each surface cover. This paper presents an empirical overland flow velocity forecasting model that can be applied to peatlands. The model combines the partially submerged component for flows with water depths below 1 cm with the fully submerged component for flows with depths up to 5 cm, which are representative of the depths of flows that occur across peatlands.
URL
http://dx.doi.org/10.1029/2007WR006052
URL Description
Abstract
Language
English
Author
Joseph Holden
Author
David G. Milledge
Author
Chris J. Brookes
Author
Mike J. Kirkby
Author
Stuart N. Lane
Author
Adrian T. McDonald
Author
Vincent Holden

peatlands; UK; overland flow velocity

Volume number
44
Is this item peer reviewed?
Yes
ISSN
0043-1397
Copyright URL
http://www.agu.org/pubs/authors/pub_fees/
Publisher
American Geophysical Union
Date of publication
01 January 2008
Number of pages
11
Place of publication
Washington, DC
Is this item a pre-print or post-print?
Postprint
Title of journal
Water resources research