Flood myth

Percentile

Statistics

Geotechnical engineering

Materials science

Mean value

Surface finish

Computer security

RADIUS

Archaeology

Computer science

Geology

Surface roughness

Computer network

Thermodynamics

Physics

STREAMS

Mathematics

Optics

Geography

Hydrology (agriculture)

Environmental science

Composite material

Dispersion (optics)

Sample (material)

E3S Web of Conferences

For measuring flood discharge with non-intrusive methods, one should know the depth-averaged to surface velocity ratio α. In this paper, a large sample of gauging (3611 gaugings over 176 sites of EDF-DTG) realized with a current meter are analyzed to compute α with three methods: fitting of a log- and a power-law and using the measured surface velocity. Results show that the three methods give very similar results, with a mean value of α of about 0.8, with few dispersion (5 th and 95 th percentile values being about 0.7 and 0.9). A link between α and the water depth is established, as α increases with the hydraulic radius. The link between α and the bed roughness, or between α and the relative roughness (Rh/d50) is not clear. Results only shows that the mean value of α is 0.8 for natural rivers (sandy, pebbly or boulders rivers), and 0.9 for artificial concrete channels.

Velocity profile and depth-averaged to surface velocity in natural streams: A review over alarge sample of rivers