Create an HEC-WAT Study from Scratch

Downloads

Software	HEC-WAT Version 1.1.0 was used to develop this guide. If you haven't done this already please review the Download and Install HEC-WAT page to download, install, open and configure the HEC-WAT software.
Example Watershed Data	The Russian River watershed is the example WAT watershed used in the HEC-WAT Version 1.1 quick start guide. Zipped dataset for this guide: RussianRiver_Maps.7z

This quick start guide provides the user with instructions on creating an HEC-WAT study from scratch and building the schematic for the default alternative.If you want a guide for creating an HEC-WAT study from scratch using existing HEC-ResSim, HEC-HMS, and HEC-RAS models, please review the Create an HEC-WAT Study from Existing Models page.

Create an HEC-WAT Study

To create a new study:

From the HEC-WAT main window, from the File menu, click New Study.
The Create New Study dialog opens. In the Study Name box, enter a name (e.g., RussianRiver), and in the Description box, enter a description for the new study.
In the Directory box, either enter the name of the directory where to store the HEC-WAT study, or click , and an Open browser window opens. Navigate to the directory to store the HEC-WAT study, click Open. The Open browser closes and the Directory box updates with the path to the selected folder.
The Unit System for the study defaults to English (which is correct for the RussianRiver study). The other choice from the list is SI (metric).
Next, the projected coordinate system of the study needs to be set. From the Create New Study dialog, click Edit (by the Coordinate System box), the Map Coordinate Information dialog opens.
For the RussianRiver study the associated map layers have the correct projected coordinate system. So, one of those map layers can be used to set the projected coordinate system for the study. From the Map Coordinate Information dialog, click Load from file (lower left corner of dialog); an Open browser window opens.
- The map layers for the RussianRiver study are located in a folder titled RussianRiver_Maps, from that folder, click on RussianSubbasins.prj (any of the map layers will work).
- Click Open and the Map Coordinate Information dialog updates with the information about the projected coordinate system.
- Click OK, the Map Coordinate Information dialog closes. Now in the Create New Study dialog the Coordinate System box contains the name of the projected coordinate system (i.e., USA_Continguous_Albers_Equal_Area_Conic_USGS_version) for the study.
HEC-WAT creates a default alternative - Without Project Conditions. If the user wants the default alternative to have a different name, several choices are available, including Other which allows the user to manually enter the name for the default alternative. For the RussianRiver study the default alternative is used.

At this point users have the option to add map layers that the PDT team has gathered for defining the study area. This step can be skipped if existing models will be imported which include an HEC-ResSim model with the stream alignment, all of the common computation points (CCPs), and the reservoirs necessary to model the study area. Otherwise, when building a study from scratch it is useful to add map layers when the study is created. To continue and create the study without adding map layers, click OK and the Create New Study dialog closes and the HEC-WAT main window updates.

Adding Map Layers

To continue to create the study with map layers:

From the Create New Study dialog, click Add Map Layers. The Select Map to Add browser opens.

To copy the map layers to the study directory area, from the Select Map to Add browser, select Create Copy. Browse to where the map layers are located (in the folder titled RussianRiver_Maps). Select the following map layers:
- Find the map layer which represents the stream gages - Raingages_Albers_ft.shp
- Find the map layer which represents the CCPs - RR_CommonComputationPoints.shp
- Find the map layer which represents the reservoirs - RR_Lakes_Albers_ft.shp
- Find the map layer that represents the stream alignment - RR_StreamAlignment.shp
- Find the map layer the represents the subbasins - RussianSubbasins.shp
Click Open, the Select Map to Add browser closes. The Create New Study dialog appears.

Create New Study Dialog Box - Completed
Click OK, the Create New Study dialog closes and the HEC-WAT main window updates with the name of the created study (RussianRiver) on the Title Bar. A Schematic Map Window opens, which contains the map layers that were added to the study.

Building the Without Project Conditions Schematic

HEC-WAT by default will create a default alternative Without Project Conditions. From the HEC-WAT main widow, the Schematic Map Window, will contain the initial schematic for the Without Project Conditions. The next step is to build the schematic for the default alternative.

Adjust Map Layers

Once a map layer is in the HEC-WAT framework the user can make adjustments to the layer. Since the map layer that represents the subbasins for the RussianRiver study is a little bit in everyone's face, let's adjust that file - RussianSubbasins.shp.

From the HEC-WAT main window, click the Maps tab. Now the user can see which Map Window is currently active and what layers make up that Map Window.

HEC-WAT Main Window - Maps Tab - Labelled

To change the color and the fill aspects of the RussianSubbasins.shp do the following:

From the Map Layers tree, right click on RussianSubbasins.shp. This is the shapefile shortcut menu. This shortcut menu allows the user to expand/collapse the RussianSubbasins.shp leaf; move the shapefile to different positions in the tree (Move To Top/Move To Bottom, Move up/Move Down); show the legend of the shapefile; change the label of the shapefile; edit the properties of the shapefile; set/remove scale factors; copy the map layer to another location; and open the attribute table of the shapefile.
From the shapefile shortcut menu, click Properties, the Edit Polygon Properties dialog box will open.
The RussianSubbasins.shp file is a polygon shapefile. To edit the fill of the active map layer, from the Fill tab, change the color or not have a fill. For the example displayed in the Edit Polygon Properties dialog, fill will be turned off. So click Display Fill, the check mark will clear, meaning that fill is turned off.
To change the outline color of the subbasin layer, from the Edit Polygon Properties dialog box, click the Border tab.
- From the Color list, select a color ("darkred").
- From the Weight list, increase the border line weight.
- Click OK, the Edit Polygon Properties dialog box will close and the changes will appear in dark red in the Map Window.
To turn off a map layer - click in the checkbox by Raingages_Albers_ft.shp, the rain gages no longer appear on the map window.
To display the map window zoomed in, select the Zoom Tool . Draw a box around the map layers that are displayed in the Map Window.
From the Maps menu, click Default Map Properties, the Default Map Properties for dialog box will open. Click Set Map Extents to Display, click OK. The Default Map Properties for dialog box will close.

This sets the extents for the Map Window so that when the study is opened the next time the Map Window will be zoomed in to the tighter area.

Create a Stream Alignment

The backbone of any schematic is the stream alignment, and is the starting point in creating a schematic. A stream alignment is a one-dimensional river coordinate system, which defines the natural downstream flow network. Also, from the stream centerline, stationing will be provided relative to its global location and specific to the study. The alignment indicates where confluences and bifurcations occur and provides a sense of distance and scale. Stream alignments are composed of a series of streams, stream nodes, and stream junctions.

The PDT has discussed the extents of the main stem for the study and has included all of the tributaries that will be considered by all of the models in the study. The PDT has created a shapefile that contains all of the pertinent streams - RR_StreamAlignment.shp.

To import a stream alignment:

From the Map Layers tree, right-click on Stream Alignment. From the shortcut menu, click Import. The Import Stream Alignment dialog opens. The Shapefile Name list defaults to the first line shapefile it can find in the maps directory; which happens to be the shapefile that represents the stream alignment for the RussianRiver study - RR_StreamAlignment.shp.
From the Database Field Name list, the user needs to select the field name in the attribute file that contains the names of the streams - Name. Once a field name is selected, the table below will populate with the streams contained in the shapefile.

Note: If there is an issue with any of the stream segments the checkbox in the Import column will not be selected. This means the stream segment is not continuous and will not be imported.
Click Reverse Direction.

The flow direction in the RR_StreamAlignment.shp shapefile is not correct. So instead of fixing the issue with ArcMap® (ESRI GIS software), by performing the Reserve Direction procedure the system of streams will have the correct flow direction.
Click Import, a message window will appear letting the user know that the stream alignment imported successfully. Click OK, the Import Stream Alignment dialog box will close. In the active Map Window the stream alignment appears (orange stream segments; green stream nodes and stream junctions).

Add the Background Internet Map

Knowing where the watershed is located in reference to known locations can be quite helpful when communicating with the PDT and stakeholders. From the Maps menu, point to Add Internet Map, from the available list select which internet map that would be a good background (i.e., Open Street Map) map for the watershed. The selected internet map will load and appear in the active Map Window.

This layer in the background might help with adding additional streams to the stream alignment; locations of reservoirs, levees, other projects, impact areas, and common computation points (CCPs). Based on the known extents of the study area, the layer provides a view of the watershed and surrounding area.

Adding CCPs

Common computation points (CCPs) are locations where one model can transfer data to another model, a location where results are needed for model development or alternative analysis, or locations where input boundary conditions are to be defined. CCPs need to be consistent for all models and should be placed on the stream alignment based on knowledge of possible study alternatives. The entire study team should be involved in the definition of the common computation points.

To import CCPs from a shapefile:

From Maps menu, point to Import, click Computation Points. The Import Computation Points dialog box will open. The Shapefile Name list defaults to the first point shapefile it can find in the maps directory; which happens to be the shapefile that represents the common computation points for the Russian River study - RR_CommonComputationPoints.shp.
From the Database Field Name list, select the field name in the attribute file that contains the names of the CCPs - ID_Name. Once a field name is selected, the table below will populate with the CCPs contained in the shapefile. If there is an issue with any of the CCPs the checkbox in the Import column will not be selected.
Click Import, the Import Computation Points dialog box will close. Once the import of the CCPs is completed, a message window will appear letting you know that the CCPs have been imported successfully. In the active Map Window the CCPs appear as black circles.

A user can also add CCPs to the schematic manually by performing the following steps:

From the Schematic Map Window, find the location where a CCP needs to be added, press the Computation Point Tool .
Hold down the CTRL key and click on the stream alignment to place the common computation point.
The Name New Computation Point dialog box will open. Enter the new Name (required) and Description (optional, but recommended). Click OK, the Name New Computation Point dialog box will close.
The common computation point will now appear in the map window as a black circle.
If a CCP is added at a stream junction, a slightly different Name New Computation Point dialog box will open. Enter the new Name (required) and Description (optional, but recommended).
From the Select the Placement of the Computation Point list, determine exactly where the common computation point will be placed. Choices are to have the common computation point placed on the stream junction, along one of the streams that form the stream junction, or none of the above. For example in the Name new Computation Point dialog the common computation point will be placed on the stream junction.
Click OK, the Name New Computation Point dialog box will close. The common computation point will now appear in the display area as a black circle.

Adding a Reservoir

A reservoir is the impoundment created behind dams, or behind navigation locks and dams. For HEC-WAT a reservoir also includes the dam built on a stream to store water for uses such as flood risk management, hydroelectric power generation, recreation use, and water supply, etc.

To add a reservoir:

From the Schematic Map Window, use the Zoom Tool and Pan Tool to find the location where a reservoir needs to be added (e.g., Lake Mendocino), press the Reservoir Tool .
Hold down the CTRL key and click on the stream alignment to place the upstream end of the reservoir. Release the CTRL key; drag the mouse to the downstream end of the reservoir and click.
The Name New Reservoir dialog box will open. Enter the new Name (Lake Mendocino) and Description (optional, but recommended). Click OK, the Name New Reservoir dialog box will close.
The reservoir will now appear on the schematic as a cyan triangle (reservoir pool), a blue line (storage reach), a gray rectangle (dam), and two common computation points that represent the upstream and downstream ends of the reservoir.
The default representation of the reservoir pool is a triangle; the user can edit this triangle if a more detailed representation of the pool is desired. With the Reservoir Tool pressed, double-click on the reservoir. The triangle will now be green with a blue outline color. Also, there are three vertex points (blue), and at the apex of the triangle is the reservoir label, which is represented by a yellow circle.
When a reservoir is created there are two common computation points that are created with default names. It is recommended that the names of the two common computation points be changed. These two common computations points represent the inflow and outflow junctions of the reservoir and should be renamed accordingly.
To change the name of a common computation point, press the Computation Point Tool , right-click on one of the common computation points (e.g., the upstream CCP for Lake Mendocino). From the shortcut menu, click Rename Computation Point; the Rename Computation Point dialog box will open. In the Name box, enter the new name, and in the Description box enter a description (optional, but recommended). For example, rename the CCP for the inflow junction for Lake Mendocino as Lake Mendocino Inflow Jct.
Click OK, a Confirm Rename window will open, asking the user to be sure that the CCP is to be renamed. Click Yes, the Rename Computation Point dialog box will close and the new name for the CCP will appear in the map window.
Repeat this step to rename the CCP outflow junction. For example, rename the outflow CPP junction as Lake Mendocino Outflow Jct.

Repeat the steps above for the Lake Sonoma reservoir.

Next Steps

After following the steps on this page to create an HEC-WAT study and add the basic schematic elements for an HEC-WAT watershed - stream alignment, common computation points, and projects (reservoirs, levees). Now this basic schematic can be used by the models that are required for the watershed.

At this point you can either:

Build the individual models in HEC-WAT, or
Build individual models outside of HEC-WAT.

If you choose to or already have individual models built outside of HEC-WAT, then please review the instructions provided here:

Create an HEC-WAT Study from Existing Models

If you are planning to do a Flood Risk Analysis simulation, review the HEC-WAT Users Manual sections detailing:

Either choice using the basic schematic built in HEC-WAT promotes collaboration with customers, partners and stakeholders involved in water resource studies. Users will be able to perform studies in an integrated and systems based approach.