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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.
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
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
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
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:
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
This is the file you will use to perform your hydrologic analysis. Mine was automatically named DEM_ProjectRaster1_1.
Preprocess the Terrain Model
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
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.
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
The fill sinks grid should look like this:
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
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.
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
.
C. Flow accumulation
Select Preprocessing -> Flow Accumulation
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
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
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
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.
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
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.
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
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:
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
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.
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
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.
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
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:
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
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.
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
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
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
Select Basin Processing -> Basin Merge. Press Yes to accept the resulting merged
sub-basin. The merged sub-basins should look like this:
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
B. River Profile
Select River Profile tool
Verify that the proper data layers are used.
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
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
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
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.
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
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.
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
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.