Enter river’s slop

[sami]

hi everybody
my question is about, how to enter the slop for a simple cross section in a river?
for example for a triangle cross section.
tnx

[Anonymous]

You don’t. You enter the cross section geometry, and the reach lengths between cross sections. RAS figures out the slope from that, for you.

[sami]

tnx but i don’t understand!
forexample for a river i just have a constant triangle cross section,whit the length of the river.
how hec-ras estimate & calculate the slope??

[Anonymous]

You need more than one cross-section to model a river. If you just want to calculate normal depth for a single cross-section at a given slope, you need a different program, like Flowmaster, or any number of free Manning’s calculation spreadsheets.

lisa

[sami]

In fact i wanna rout the flood hydrograph in downstream of a river with a constant triangle cross section.i have the river’s slope and the geometry of cross section but i don’t know whether the slope is necessary or not? and where in hec-ras should i enter it?

[Anonymous]

You don’t need to enter a slope. RAS will calculate the slope based on the elevation of the cross-sections and the downstream reach lengths you enter in the cross-section data.

[Author]

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