Compute geometry relations for trapezoidal channels.

channel_geom(y, B, SS)

## Arguments

y |
Flow depth [\(L\)]. |

B |
Channel bottom width [\(L\)]. |

SS |
Channel sideslope [\(L L^{-1}\)]. For a rectangular channel, `SS = 0` . |

## Value

Named vector:

AFlow area [\(L^2\)].

PWetted perimeter [\(L\)].

RHydraulic radius [\(L\)].

dAdyWater surface width [\(L\)].

dPdyFirst derivative of wetted perimeter w.r.t. flow depth.

dRdyFirst derivative of hydraulic radius w.r.t. flow depth.

DHHydraulic depth [\(L\)].

ybarVertical distance from water surface to centroid of flow area [\(L\)].

## Details

Channel geometry relations are routinely calculated in numerical solutions of steady,
gradually-varied and unsteady flows. This function is used extensively by internal
procedures and is made accessible to the user for convenience.

## Examples

channel_geom(1.71, 100, 0) # rectangular channel

#> A P R dAdy dTdy dPdy
#> 171.0000000 103.4200000 1.6534519 100.0000000 0.0000000 2.0000000
#> dRdy DH ybar
#> 0.9349555 1.7100000 0.8550000

channel_geom(5.79, 6.1, 1.5) # trapezoidal channel with sideslope 3H:2V

#> A P R dAdy dTdy dPdy dRdy
#> 85.6051500 26.9761419 3.1733652 23.4700000 3.0000000 3.6055513 0.4458854
#> DH ybar
#> 3.6474286 2.3281400