Abstract:
Mathematical predictions of flow conditions along a steep gradient rock bedded stream
are examined. Stream gage discharge data and Manning's Equation are used to calculate
alternative velocities, and subsequently Froude Numbers, assuming varying values of
velocity coefficient, full depth or depth adjusted for vertical flow separation. Comparison
of the results with photos show that Froude Numbers calculated from velocities derived
from Manning's Equation, assuming a velocity coefficient of 1.30 and full depth, most
accurately predict flow conditions, when supercritical flow is defined as Froude Number
values above 0.84. Calculated Froude Number values between 0.8 and 1.1 correlate well
with observed transitional flow, defined as the first appearance of small diagonal waves.
Transitions from subcritical through transitional to clearly supercritical flow are
predictable. Froude Number contour maps reveal a sinuous rise and fall of values
reminiscent of pool riffle energy distribution.
