Estimation of flow conditions in steep torrents : A Master Thesis for completing the degree Land and Water Management and Engineering, University of Natural Resources and Applied Life Sciences (BOKU), Vienna

Wien

2007

130 S.

Monographie

15913

147585

"A new hypothesis predicts that in mobile-bed river channels, interactions between the channel hydraulics and bed configuration prevent the Froude number from exceeding one for more than Short distances or periods of time" (Grant, 1997, p. 349). If this hypothesis proves true, it could have significant implications for the practical evaluation of hazards, as it simplifies the estimation of the hydraulic conditions. For instance, the assumption that flow conditions are near critical flow allows for calculation of flow velocity directly from the flow depth (Grant, 1997; Tinkler, 1997a). The aim of this thesis is to identify whether there is a trend correlating change in flow conditions of torrents with discharge (different return periods), slope and roughness and how often supercritical flow is actually present in different cross sections along the channel network. This thesis does not wish to prove or disprove Grant's hypothesis mentioned above, as it is not based on surveyed flow conditions.