Automating HEC-RAS with Excel

Automating HEC-RAS with ExcelVirginia Lakes and Watersheds Conference, March 2015

Thomas Williams, PE

Amec Foster Wheeler

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Contents

1. What is HEC-RAS? (brief intro)

2. The HECRASController API

3. Excel VBA Demos

1. Multi-Model Run

2. RAS Output Extraction

3. Manning’s ‘n’ Calibration (sort of)

4. Tips

5. Conclusion

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1. What is HEC-RAS?

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Hydrologic

Engineering

Centers

River

Analysis

System

“HEC-RAS allows you to

perform one-dimensional

steady flow, unsteady flow,

sediment transport/mobile

bed computations, and water

temperature modeling.”

- USACE

What is an API?

API = Application Programmer Interface

“In computer programming, an application programmer interface (API) is

a set of routines, protocols, and tools for building software

applications. An API expresses a software component in terms of its

operations, inputs, outputs, and underlying types.”

- Wikipedia

2. The HECRASController API

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Their Program

Your

Program API

2. The HECRASController API (cont’d)

The HECRASController API

“The current version of the HECRASController has a wealth of

procedures that will allow a programmer to manipulate HEC-RAS

externally by setting input data, retrieving input or output data, and

performing common [HEC-RAS] functions…”

- Christopher Goodell, PE, D.WRE, Breaking the HEC-RAS Code, 2014

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HEC-RAS

ExcelAPI


Accessing the API from Microsoft Excel

1. Click the Visual Basic button (on the Developer tab)

2. Create a new VBA module

3. Go to Tools > References, check “HEC River Analysis System”,

and click OK.

4. Write code!

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A simple program…

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Sub RunHECRAS()

' Opens and runs a HEC-RAS model

' Declare variables

Dim ras As New HECRASController

Dim nmsg As Long

Dim strMessages() As String

Dim prjFilePath As String

' Open the model

prjFilePath = "C:\MyHecRasModel.prj"

ras.Project_Open (prjFilePath)

' Run the model

ras.Compute_CurrentPlan nmsg, strMessages

End Sub


Some example HECRASController

fuctions and subroutines:

• Project_Open

Opens a HEC-RAS model.

• Compute_CurrentPlan

Runs the current flow/geometry

regime.

• ExportGIS

Exports an *.sdf file that can be

read into ArcGIS using HEC-

GeoRAS.

• Output_NodeOutput

Returns an output value for a

given node and profile.

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• Geometry_SetMann

Sets the Manning’s ‘n’ values for

a cross section, horizontally

varied.

• Add_BC

Adds a bridge/culvert.

• Edit_BC

Opens the Bridge/Culvert Editor

and displays the selected station.

• PlotPF

Displays the water surface profile

for a given River/Reach.

3. Excel VBA Demos

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1. Multi-Model Run

2. RAS Output Extraction

3. Manning’s ‘n’ Calibration (sort of)

Cross your fingers!

4. Tips

• Breaking the HEC-RAS Code

by Christopher Goodell, PE, D.WRE

• The API is a little rough around the edges.

• Provides a lot of functionality, but not everything

• Inconsistencies:

• Parameter names and types

• Function / subroutine behavior

• No “official” API documentation

• HEC-RAS is public domain software, but not open source

• HEC-RAS project (*.prj), geometry (*.g##), flow (*.f##), and plan

(*.p##) files are plain text.

• Sometimes that’s easier than using the API.

• HEC-RAS output files (*.O##) are binary.

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5. Conclusion

1. The HECRASController API is really useful…

2. …but it takes a little work to figure out.

3. Happy coding!

Questions?

Contact Info

Thomas Williams, PE

Amec Foster Wheeler

[email protected]

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