WMS

Modeling a Dam in GSSHA

By aquaveo on May 1, 2019

Do you have a project that requires modeling a dam, or similar structure, in GSSHA? WMS can make this process smoother with tools designed to help define the structure quickly and efficiently.

In order to create a simulation that includes modeling the dam in WMS and analyzing the dam’s effects using GSSHA, the workflow is as follows:

Import an existing GSSHA base model.
In the GSSHA map coverage, use the Shift key to select the node where you want the dam to be and the node immediately downstream from it.
Right-click on the selected nodes and select Attributes to open a Properties dialog.
Select Output Hydrographs at those nodes.
Run GSSHA.
Using the results from the GSSHA run, size your embankment based on the necessary storage.
Using the Create Feature Arc tool, create an arc to represent your dam.
Double-click on the arc to bring up the Attributes dialog.
Set the type of arc to be an Embankment, then click the ... button next to it to open the Embankment Arc Profile Editor dialog.

Set the PVI Elevation to be the height of the dam.
Click Compute Vertical Curve to compute the Curve Length.

Double-click the node in the stream where your structures will be defined to open the Properties dialog.
Click the button under Hydraulic structures to open the GSSHA Hydraulic Structures dialog.

Add a Detention Basin, Weir and Culvert.
Define the attributes for each of these structures.

Run GSSHA again to see the effects of the dam you have created.

If needed, adjust the display options when reviewing the results to get a better idea of how the dam structure affected the results. Try different various options to get a better feel of how the dam affected the simulation results.

Now that you know how to add a dam to GSSHA, try out modeling dam structures and other applications in WMS today!

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WMS

Modeling a Dam in WMS for Use in HEC-HMS

By aquaveo on April 10, 2019

Do you have a project that requires modeling a dam, or similar structure, in HEC-HMS? WMS can make this process smoother with tools designed to help define the structure quickly and efficiently.

This blog presents a workflow for modeling a dam in WMS to later analyze in HEC-HMS. The workflow is as follows:

Begin with a delineated watershed with attributes defined.
Determine where you would like to place your reservoir and place an outlet point there.
Delineate your watershed and compute basin attributes using your new outlet point.
Create a simulation in HEC-HMS and compare the runoff from the upper basin to the lower basin in order to size your reservoir.
Convert the outlet node to a reservoir.

Switch to Hydrologic Modeling Module.
Using Select outlet tool, select the outlet at the location where you want to model a reservoir.
Right-click and select Add | Reservoir.

Select Calculators | Detention Basins.
Click Define to bring up Storage Capacity Input.

For a dam: Use DEM and enter the height of the desired dam.
Click OK to exit Storage Capacity Input dialog. The Detention Basin Analysis dialog will appear.
Define the storage curve for your reservoir.
Click Map to Hydrologic Model to open Map to Model. Name the series as desired.

Double-click on the reservoir point to open the HMS Properties dialog.

Here, you can choose the storage curve defined earlier, and define all other curves.
To add an orifice to your dam, select Orifice Outlet from the Outlet Type drop-down.

Define the orifice Center Elevation, Cross-sectional Area, and Discharge Coefficient.

To add a spillway, select Broadcrested Spillway or Ogee Spillway from the Spillway Type drop-down.

Define the required characteristics for the selected spillway.

You can also choose to model an overflow type and dam break type if desired.

With the dam, spillway and orifice defined, you can now run your model through HEC-HMS again to see how your reservoir will perform under the selected storm.

Try out modeling dam structures and other applications in WMS today!

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WMS

Delineating a Floodplain Using a Scatter Point File

By aquaveo on March 20, 2019

Looking for a quick way to delineate a floodplain in your area? WMS provides a way to delineate a floodplain and create a flood impact map quickly, using many different types of data. This blog post will cover how to delineate a floodplain using scatter point data.

Start by opening your scatter point data:

Use the Flood | Read Stage File menu command to import your scatter point dataset. This is the recommended method for importing a scatter point set for using in delineating a floodplain.

Delineating the Floodplain

With the scatter point set imported, now delineate the floodplain.

Select Flood | Delineate menu command.
In the Floodplain Delineation dialog, choose the scatter point set you would like to model from the Select stage scatter point set drop-down menu.
Select the specific dataset you would like to delineate from the Select stage data set drop-down menu.
Set options for the Search radius, Flow path, and/or Quadrants depending on your individual model.
When done with the Floodplain Delineation dialog, the delineation process will begin for the set of water surface elevations selected.

In order to create a flood impact map, it will be necessary to have at least two different delineations using varying datasets. If you wish to go on to create a flood impact map, repeat steps 1-5 with a different dataset to obtain a new floodplain delineation.

Creating a Flood Impact Map

WMS can use two separate floodplain delineations to generate a flood impact coverage. A flood impact coverage shows the difference between two flood depth or water level sets. The differences are divided into ranges or classes. Using the floodplains delineated in the previous steps, we’ll create a flood impact map. This can be used to compare how an area will react to a proposed levee for example.

Select Flood | Conversion | Flood → Impact Map menu command.
Choose the Original dataset based off your previous delineations.
Choose your Modified dataset based off your previous delineations as well.
Set the Increase and Decrease sections as desired.

Now that the flood impact map is created, you can use the Select Feature Polygon tool to double click on any of the polygons in the map. This will show you the Flood Extent Attributes dialog, which displays info such as the amount of change between the compared datasets as well as the impact class ID and name.

So this a brief overview of floodplain delineation from a scatter point file using WMS. Try it out in WMS today!

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WMS

Using the Channel Calculator in WMS

By aquaveo on February 20, 2019

With WMS there is no need to sit and calculate your channel properties by hand, you can use the Channel Calculator to help you obtain the hydraulic data you need. The Channel Calculator, a function of the Hydraulic Toolbox, has the ability to give values for flow, depth, area of flow, wetted perimeter, hydraulic radius, average velocity and so much more. Even better, the Channel Calculator only requires some basic cross-section data including the slope and either the flow or depth of the channel.

This blog post will cover how to compute depths for your channels, which can be used to create floodplain delineation maps, and also how to generate rating curves for your channels, which can be used for things such as predictions. To get started, make sure you have cross-section arcs and river centerlines in your model.

To Compute Depths:

The Channel Calculator is a good tool for approximating channel flows or flow depths. Given a flow rate, the Calculator can compute a flow depth, and vice versa.

In the Hydrologic Modeling Module, select Calculators | Channels to open the Channel Calculations dialog.
Toggle on the Use Cross-Section Database option to enable the ability to import existing cross-section data.
Click the Select Cross Section button to bring up the Assign Cross-Section dialog.
Select your cross-section file along with the cross-section you would like to work with.

The cross section displays in the small graphics window of the Channel Calculations dialog. Adjust the Z scale using the drop-down menu to better visualize the cross section. With the cross section selected, set the necessary parameters to perform calculations for depths.

Click the Launch Channel Calculator button to open the Channel Analysis dialog.
Enter a value for Longitudinal slope. This is an estimate for the ground slope in the vicinity of your cross-section.
Enter a value for the Flow or the Depth depending on which values you have and which ones you are trying to find.
Select the Calculate button. This will populate the right-side of the dialog with hydraulic values calculated for the cross-section.
Select the Create Stage Point button in the Channel Calculations dialog to create a stage point based off the values computed in the channel calculator. This is useful if you are planning to use the depths to delineate a floodplain later on.

To Generate a Rating Curve:

The Channel Calculator can also be used to create different rating curves, to be used to calculate things such as storage potential.

Click on the Launch Channel Calculator button to open the Channel Analysis dialog.
Select the Compute Curves button to open the Curve Selection dialog.

The default is to create a rating curve for the entered flow vs. depth for the selected cross section, but it’s possible to also create curves for all of the other options listed.

When exiting the Curve Selection dialog, the selected rating curves are generated and the plot shouldappear.
If you double-click in the rating curve plot window a dialog will appear that presents many different options for how you can use the rating curve, including an option to export the curve in a chosen format.

As you can see, with just a few steps, you can obtain the hydraulic data you need for your channels in WMS. Try it out today!

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WMS