Sediment Transport with HEC-RAS 4.0

[Gkrotti]

Dear all,

I'm using HEC-RAS 4.0 to analyze solid transport in a mountain river. I
started my study with simple cases (for example rectangular channel and
constant slope) to understand as better as possible HEC program. I have some problems to perform a sediment transport simulation.

CASE A
General Rectangular section (10x10 m)
Roughness coefficient: 70 m1/3/s
Slope: 1%
Length: 10 km
Discharge: 200 m3/s ( Normal depth "h0" = 2,17 m, Critical depth "k" = 3,44
m)
Sediment Max Depth: 5 m
Bed Gradation: Medium Boulders (512-1024 mm)
Boundary condition: Equilibrium Load (upstream)

Expected Results: Normal depth and no bed erosion
HEC Results: Critical depth and no bed erosion

CASE B
General Trapezoid section (H = 10 m B max = 12 m, B min = 10)
Roughness coefficient: 70 m1/3/s
Slope: 1%
Length: 200 m (Äs = 10 m)
Discharge: 200 m3/s ( Normal depth "h0" = 2,12 m, Critical depth "k" = 3,40
m)
Sediment Max Depth: 5 m
Bed Gradation: Medium Boulders (512-1024 mm)
Boundary condition: Sediment time series (upstream)
Boundary condition: Sediment time series like upstream (in the middle)

Expected Results: Normal depth, no bed erosion, aggradation in upstream and
middle sections.
HEC Results: Critical depth, no solid transport, aggradation only in
upstream section.

CONCLUSION
I can't obtain a super critical profile. Today I have news about this topic. HEC-RAS default to critical depth when in sediment transport simulation profile going under critical depth.
Internal boundary condition doesn't run although it is the same that
upstream one.

can you help me, please??

thanks

Gianluca