hec-geohms toolbar in arcmap - mit libraries · iap 2014 hydrology tools exercise january 2014 ......

IAP 2014 Hydrology Tools Exercise January 2014 Anne Graham

Exercise based on: http://www.hec.usace.army.mil/software/hec-geohms/documentation/HEC-GeoHMS_Users_Manual_10.1.pdf Chapter 13

HEC-GeoHMS toolbar in ArcMap

The tools we will be using today to create a watershed are all described well in

the US Army Corps of Engineers User Manuals:

http://www.hec.usace.army.mil/software/hec-geohms/documentation/HEC-

GeoHMS_Users_Manual_10.1.pdf

http://www.hec.usace.army.mil/software/hec-georas/documentation/HEC-

GeoRAS_43_Users_Manual.pdf

We will use a Digital Elevation Model covering the area west of Mount Elgon in

Uganda.

Add DEM.tif (it is a mosaic of 4 panels downloaded from the NASA website called

Reverb|ECHO.

http://reverb.echo.nasa.gov/reverb/#utf8=%E2%9C%93&spatial_map=satellite&s

patial_type=rectangle)

Before you work with a DEM it should be projected so that your calculations will be as accurate as possible.

Right click on the file name in the table of contents, and click on properties. Then click on the Source tab. Scroll down to see that the data has a defined datum: WGS84.

To create a file that will preserve areas, we will project this file into the Projected Coordinate System: WGS_1984_UTM_Zone_36N, which is the

projection for this data. Open the search box and search for “Project Raster.” Double click on Project Raster to open the tool’s form.

Fill in the form with DEM as the input raster, call the output raster dataset DEM_ProjectRaster, and for the output coordinate system, navigate to through the Projected Coordinate System folder into the UTM folder > World > WGS 1984 > Northern Hemisphere, scroll to WGS_1984_UTM_Zone_36N.

http://www.hec.usace.army.mil/software/hec-geohms/documentation/HEC-%09GeoHMS_Users_Manual_10.1.pdf

http://www.hec.usace.army.mil/software/hec-geohms/documentation/HEC-GeoHMS_Users_Manual_10.1.pdf

http://www.hec.usace.army.mil/software/hec-geohms/documentation/HEC-GeoHMS_Users_Manual_10.1.pdf

http://www.hec.usace.army.mil/software/hec-georas/documentation/HEC-GeoRAS_43_Users_Manual.pdf




http://reverb.echo.nasa.gov/reverb/#utf8=%E2%9C%93&spatial_map=satellite&spatial_type=rectangle

http://reverb.echo.nasa.gov/reverb/#utf8=%E2%9C%93&spatial_map=satellite&spatial_type=rectangle



Your tool should look like this:

Click OK. It will take a minute or two, but when the projection is completed, you

will get a message, and your projected file “DEM_ProjectRaster” will be added to

the table of contents.

The first file added to any ArcMap project give the Data Frame its projection. To

match the Data Frame to this newly projected DEM, right click in the area where

the DEM is displayed, then click on Data Frame Properties. Click on the

Coordinate System tab, and note that the Data Frame is in the WGS-84 coordinate

system, but it doesn’t yet have the UTM Zone 36N Projection. To match the Data




Frame to the projected DEM, scroll down to the yellow folder that says Layers.

Click to open the Layers folder, and click on WGS_1984_UTM_Zone_36N. Click OK

to accept this projection for the Data Frame.

For use with the HEC-Geo tools the DEM_ProjectRaster.tif must be converted to a

GRID using the Raster to other Format tool. Use the Search for this tool. Fill out

your tool like this:




This is the file you will use to perform your hydrologic analysis. Mine was automatically named DEM_ProjectRaster1_1.

Preprocess the Terrain Model




1. Load the HEC-GeoHMS toolbar. In the Customize menu, select Extensions and

turn of Spatial Analyst. Then in the Customize menu, select Toolbars and check

the HEC-GeoHMS toolbar. It will appear in the header area looking like this:

2. View the properties of the DEM: right-click on the name DEM_ProjectRaster1_1

(or the name given to your Grid) in the table of contents and select Layer

Properties. Then the Source tab. Note that there are about 18 million cells (3376

rows * 5235 columns) at 30 meters resolution. This covers a rectangular area of

about 16,000 km2 (6,100 square miles), about the size of Connecticut and Rhode

Island combined.

3. In the Geoprocessing menu, click on Environments and then Workspace.

Change the paths to send your work in the folder you have set up for this project.

Here is an example. Use your own path.

Save the project using the File Save As menu, navigating to the folder you are

using for this project. You can call the project River1.

4. Drainage analysis

A. Fill Sinks – From GEO-HMS toolbar, select Preprocessing > Fill Sinks. Use

the DEM that you turned into a GRID. Call the output file FIL to look like the

dialog box below. The process takes several seconds.




The fill sinks grid should look like this:




B. Flow Direction

Select Preprocessing > Flow Direction. Use FIL as the input Hydro DEM. Call the

output Flow Direction, Fdr. Press OK. This step takes several seconds. The flow

direction grid should look like the screenshot below. Note that the colors indicate

direction of flow from each grid cell. Remember the 8 direction flow direction

model.




.

C. Flow accumulation

Select Preprocessing -> Flow Accumulation




Confirm that the input Flow Direction Grid is Fdr. Call the output Flow

Accumulation Grid Fac. Press OK. This step takes a few minutes. It should look

like the screen shot below. It doesn’t appear complete, but it is. Zoom into a part

of the stream network on the west side of the mountain to display the details of

the grid cells that make up the flow accumulation grid. Grid cells with a value of 0

are located on the topographic divide and grid cells with a large value make up

the stream network.

D. Stream Definition

Select Preprocessing -> Stream Definition.

Confirm that the input Flow Accumulation Grid is Fac and call the output Stream

Grid Str. Accept the default Number of cells to define stream. Press OK. Zoom in

to see the grid cells that make up the stream definition grid.

E. Stream Segmentation




Select Preprocessing -> Stream Segmentation

Confirm that the input Flow Direction Grid is Fdr and Stream Grid is Str. The

output Stream Link Grid is StrLnk. Press OK.

F. Catchment Delineation

Select Preprocessing -> Catchment Grid Delineation

Confirm that the input Flow Direction Grid is Fdr and Link Grid is StrLnk. Call the

output Catchment Grid, Cat.

Press OK. The processing will take just under a minute. Your catchment grid

should look like this.

G. Catchment Polygon Processing

Select Preprocessing -> Catchment Polygon Processing.




Confirm that the input Catchment Grid is Cat. Call the output Catchment layer

Catchment.

Press OK. This process does a lot of organizing work for you. It automatically sets

up a geodatabase for the polygons, and places them in it. Note the path

difference. If you watch the processing, you will see that HydroIDs are assigned,

GridIDs are populated, and Indexes are built to organize your data.

The catchment polygons should look like ths:

H. Drainage Line Processing

Select Preprocessing -> Drainage Line Processing.

Confirm that the input Stream Link Grid is StrLnk and that the Flow Direction Grid

is Fdr. Call the output Drainage Line, DrainageLine. Note that it also gets put in

the new geodatabase.




You will see the drainage lines within the catchments.

I. Watershed Aggregation

Select Preprocessing -> Adjoint Catchment Processing.

Confirm that the input Drainage Line is DrainageLine and that Catchment is

Catchment. Call the output Adjoint Catchment, AdjointCatchment.

Press OK. The aggregated catchment looks like this:




5. Extract project specific data

In the next step, the study area is defined by identifying an outlet. HEC-

GeoHMS will extract data for the drainage area upstream of the defined

outlet. A new ArcMap data fram will be populated with the project specific

data. Tools on the Project Setup menu can be used to interactively delineate

the project area and create input files for an HEC-HMS project.

Add the stream flow gage layer called Gages2.

Zoom closely in on this gage and make the Strlnk layer visible. We will analyze

the watershed that drains to this stream gage.

Select Project Setup. Accept the default names for the Project Area and Project

Point layers.

The Define a New Project editor opens automatically. Enter BigRiver as the

project Name and GeoHMS of Big River as the Description. Accept other

defaults and press OK.




Read the information in the Start New Project window before closing it.

On the toolbar, click on the Add Project Points button and click on the cell

located at the gage to specify the outlet location.




Name the outlet point OutletBigRiver and accept Outlet1 for the description.

Press OK, select Project Setup -> Generate Project. Verify that the proper data

layers are used as shown here:




The basin upstream from the selected outlet will become highlighted, and the

program will prompt you to create a project of the area. Press Yes to create a

project for the highlighted area.

Press OK to accept the default names in the Generate Project window. To see

the extracted catchment relative to the entire area, turn on the MainViewDEM

layer. You can play with its symbology by changing the coTheslor ramps in its

properties -> symbology dialog box.




The datasets above the outlet were extracted and added to the BigRiver data

frame. These datasets will be used for additional basin processing, extracting

basin characteristics, and developing HEC-HMS inputs.

Basin Processing

6. Revise subbasin delineation.

A. Merge Basins (merges selected sub-basins into one)

Select the five sub-basins shown below with the Select Features tool




Select Basin Processing -> Basin Merge. Press Yes to accept the resulting merged

sub-basin. The merged sub-basins should look like this:




B. River Profile

Select River Profile tool

Verify that the proper data layers are used.




Click on the highlighted river segment to see its river profile.

7. Extract physical characteristics of streams and sub-basins and save them in

attribute tables.

A. River Length




Select Characteristics -> River Length. Press OK after making sure the river layer is

selected. A “RivLen” column in the attribute table is updataed with estimates of

the river segment lengths.

8. Develop hydrologic parameters

A. Select Parameters -> HMS Processes. Make sure the sub-basin and river layers

are selected and press OK.

Select Initial+Constant for Loss Method, Clark for Transform Method. Non for

Baseflow Method and Lag from Route Method. Press OK.




B. River Auto Name

Select Parameters -> River Auto Name. Make sure the river layer is selected and

press OK. This step creates a “Name column in the river layer’s attribute table as

shown below. In a real study, you should manually edit the names.

C. Basin Auto Name

Select Parameters -> Basin Auto Name. Make sure the sub-basin is selected and

press OK. This step creates a “Name” column in the subbasin layer’s attribute

table as shown below.




9. Develop HMS inputs

A. Select HMS -> Check HMS Data. Press yes to review the log file.

I have an error here. Some troubleshooting is necessary.


hec-geohms toolbar in arcmap - mit libraries · iap 2014 hydrology tools exercise january 2014 ......

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