Flow splitting in HEC-RAS
Flow splitting in HEC-RAS
(OP)
I am trying to figure out a way to split the flow in a HEC-RAS model. I have a main channel that has a distributary that splits off near the end of the main channel. Here are the knowns:
Main Channel Distributary
L = 16000 ft L = 1400 ft
A = 1675 ft2 A = 686 ft2
Q = 14000 cfs Q = ?
R = 7.9 R = 3.4
What I am attempting is to find what percentage of flow diverts from the main channel and into the distributary since HEC is requesting a flow at the beginning of the distributary and just beyond the distributary in the main channel.
I also had to run HEC-RAS with bogus flows at each of these junctions in order to obtain my wetted perimeter and flow area. For simplicity, I made sure the entire area and perimeter were used.
Any tips?
Main Channel Distributary
L = 16000 ft L = 1400 ft
A = 1675 ft2 A = 686 ft2
Q = 14000 cfs Q = ?
R = 7.9 R = 3.4
What I am attempting is to find what percentage of flow diverts from the main channel and into the distributary since HEC is requesting a flow at the beginning of the distributary and just beyond the distributary in the main channel.
I also had to run HEC-RAS with bogus flows at each of these junctions in order to obtain my wetted perimeter and flow area. For simplicity, I made sure the entire area and perimeter were used.
Any tips?





RE: Flow splitting in HEC-RAS
Q1 = Q2*(SQRT(L2/L1))*(A1/A2)*(R1/R2)^(2/3)
Am I wondering down the right track here?
RE: Flow splitting in HEC-RAS
Should I be matching up the energy grade elevation and water surface elevation at the junction for each of the (3) cross sections (upstream of split, distributary, and downstream of split) within a certain tolerance?
RE: Flow splitting in HEC-RAS