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WATER-SURFACE PROFILES
- To perform the HEC-RAS modeling, the design channel alignment was obtained from Tijuana officials.
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The project has a total channel length of 9880.849 m.
The upstream point, with invert elevation 80 m, is at the bridge over Cañon del Padre, on the toll road to Tecate.
The downstream point, with invert elevation 40 m, is at the beginning of the
concrete-lined reach of Arroyo Alamar,
near the confluence with the Tijuana river.
This provides an average channel slope of 0.004048.
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The project reach, of length 9880.849 m,
was subdivided into reaches at an equidistance of 20 m,
for a total of 494 reaches and 495 cross sections.
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A prismatic channel of a chosen cross-sectional geometry was adopted for design. The channel consists of
a main channel and left and right overbank channels (flood plains). The bottom width of the main channel
is 40 m, and the main channel depth is 3.8 m.
The side slopes of the main channel are 2 horizontal to 1 vertical.
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The overbank channels are 20 m wide each, with channel depth 3.0 m. and side slopes 2 H:1 V.
The overbank channels drain into the main channel with a 1% transversal slope.
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Manning's n values for inbank channel flow was estimated at 0.035, and for overbank flow at 0.075. These values are consistent
with established practice.
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