The University of br/itish Columbia


bend-angle function (BAF) : A function of change in slope angle (dTHi), change in path azimuth (dAZi), and incoming flow volume (Vi-1) for a given reach i defined by :
     BAFi = cos(dTHi) cos(dAZi) ln(ΣVi-1)

confined flow (CF) : Flow within a gully channel (width of the flow is constrained by hillslope topography).

cumulative flow volume : Total volume of the event at a given reach along the debris flow path.

debris fan : Deposition zone of a debris flow which occurs as a result of a reduction in the slope angle, and a transition from confined to unconfined flow behaviour.

debris yield rate (m3/m) : Volume of material deposited in the terminal deposition area (m3) per unit distance (m) from point of origin to onset of terminal deposition.

deposition : Loss of material leading to a decrease in cumulative flow volume.

entrainment : Accumulation of material by a process of erosion, leading to an increase in cumulative flow volume.

A debris flow showing entrainment followed by deposition.
A debris flow showing entrainment followed by deposition in a debris fan.

initial [failure] volume (m3) : User-defined volume at the onset of failure.

length (L (m)) : Slope length of a reach.

mode of flow : Unconfined flow, confined flow, or transition flow.

path azimuth (AZ (°)) : Angle (in degrees) of the lengthwise axis of a reach (measured facing down the slope, in degrees clockwise from north).

Initiation zone of Blueberry Creek.
Point of origin of Blueberry Creek.

point of origin : Location of the onset of failure.

point of terminal deposition : Location of the front of the debris flow, where it comes to a halt.

reach : portion of an event path having a distinctive morphology, length, width, and orientation.

slope angle (TH (°)) : Angle (in degrees) of the slope of a reach (measured up from the horizontal).

transition flow (TF) : Flow on the first open-slope reach after a confined reach (typically occurs on the apex of a fan, but may also occur where a confined event crosses a road.

travel distance : Slope distance along the travel path, from point of origin to point ot terminal deposition.

unconfined flow (UF) : Flow on an open-slope reach, including the headwall, sidewall, or fan of a gully or a road.

width (W (m)) : Width of a reach, established with reference to the occurrence of entrainment or deposition along the path of the event.

Reach 17 of Blueberry Creek, with a width of three metres.
Reach 17 of Blueberry Creek, a reach of confined flow.