New Features for HEC-RAS 5.0.4+

Martin Teal, P.E., P.H., D.WRE

September 4, 2018

Thanks to HEC Staff:• Stanford Gibson, Ph.D.• Alex Sánchez, Ph.D.

2017 Topics – 5.0 to 5.0.3+

1. Unsteady Sediment Transport

2. USDA-ARS Bank Stability and ToeErosion Model (BSTEM)

3. Other New Sediment Features

2018 Topics – 5.0.3 to 5.0.5+

1. Transport Function Calibration / Modification

2. Variable Sediment Properties3. 2D Connection4. Internal Stage BC (Quasi-

Unsteady)5. Sediment Rules

2018 Topics – 5.1+

1. 2D Sediment Transport

3. Stochastic Sediment (WAT)4. New Viewer

2. Non-Newtonian Flow

REMINDER - Develop and Calibrate a Good Hydraulic Model First

-Variable n-values-Ineffective Flow Areas

HEC-RAS Sediment Data InputStarts here:

2018 Topics – 5.0.3 to 5.0.5+

1. Transport Function Calibration / Modification

2. Variable Sediment Properties3. 2D Connection4. Internal Stage BC (Quasi-

Unsteady)5. Sediment Rules

Transport Function Calibration / Modification1. “Exposes”

transport parameters

2. Two ratios added for calibration

Variable Sediment Properties1. Editor expanded to include other

properties

2. Allows gaps and overlaps in grain size properties (check box)

2D Sediment Connection

1. Passes sediment from unsteady 1D model to a 2D area using a lateral structure

2. Since no 2D sediment (yet), simply becomes a sink

Internal Stage Boundary Condition1. Quasi-unsteady enhancement

2. ISBC – time series of fixed stages at any X-Sec

a. Overrides TS Gate Openings

b. Useful in dam removal / flushing

Sediment Rules1. RAS can operate structures based on

bed change at a cross section or sediment concentration (e.g., downstream TMDLs).

2018 Topics – 5.1+

1. 2D Sediment Transport

3. Stochastic Sediment (WAT)4. New Viewer

2. Non-Newtonian Flow

2D Sediment TransportCo-development for RAS & HMSFinite Volume:

Mass conservativeUnstructured polygonal mesh:

Maximum flexibilityImplicit:

Robust for large time stepsDetailed subgrid bathymetry

Partial wetting and drying Allows for much larger cells while maintaining

accuracy

Subgrid Modeling

Rain

Channel

Percolation

Computational Cell

Wet Dry

• Representation of the physical terrain and processes at a subgrid scale

• Allows for larger grid cells reducing computational cells, and computational times

Subgrid Modeling

Hydrodynamics

Ele

vatio

n

Area

Ele

vatio

n

Volume

Subgrid Modeling

Flow

Sediment

ElevationArea

Elevation

Area

Elevation

Area

Elevation

Area

0 50 100 150 200 250-5.5

-5

-4.5

-4

-3.5

-3

-2.5

-2

-1.5

Time step

Ele

vatio

n, m

Bed Layering Example

2D Prototype Model Validation

Bed

Cha

nge

(ft)

Cur

rent

Vel

ocity

(m/s

)C

once

ntra

tion

(mg/

L)

Elev

atio

n (ft

)

Fargo Model From MVP

HEC contacted several districts to find promising 2D validation data sets on the prototype scale and are acquiring data from MVS and NWP.

2D Prototype Model Validation

Non-Newtonian FlowFlow Type ModelHyperconcentrated Bingham PlasticMudflow Quadratic (Turbulent)Debris Flow Quadratic (Turbulent + Dispersive)

Stochastic Sediment with HEC-RAS and HEC-WAT

New 5.1 Sediment Results Viewer

Questions?

Holtwood Dam, September 10, 2011 (TheGates1210 on YouTube)

Bank-Bed Scour CalibrationHEC-RAS/BSTEM Model

of Missouri River D/S of Gavins Point Dam

BSTEM