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Hydraulic modeling of runoff over a rough surface under partial inundation
Author(s) -
Roche N.,
Daïan J.F.,
Lawrence D. S. L.
Publication year - 2007
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/2006wr005484
Subject(s) - froude number , flow (mathematics) , mechanics , laminar flow , hydraulic roughness , reynolds number , surface runoff , surface roughness , open channel flow , surface finish , geology , turbulence , geotechnical engineering , materials science , physics , ecology , biology , composite material
This study presents a numerical method to derive the Darcy‐Weisbach friction coefficient for overland flow under partial inundation of surface roughness. To better account for the variable influence of roughness with varying levels of emergence, we model the flow over a network which evolves as the free surface rises. This network is constructed using a height numerical map, based on surface roughness data, and a discrete geometry skeletonization algorithm. By applying a hydraulic model to the flows through this network, local heads, velocities, and Froude and Reynolds numbers over the surface can be estimated. These quantities enable us to analyze the flow and ultimately to derive a bulk friction factor for flow over the entire surface which takes into account local variations in flow quantities. Results demonstrate that although the flow is laminar, head losses are chiefly inertial because of local flow disturbances. The results also emphasize that for conditions of partial inundation, flow resistance varies nonmonotonically but does generally increase with progressive roughness inundation.