K. Hypothetical Hurricane
From SCOOP Wiki
This lesson demonstrates how different coastal conditions during the landfall of a hurricane can affect storm surge. You will be using a GUI which runs CH3D-SSMS (Storm Surge Modeling System) to simulate the storm surge at a hypothetical coast resulting from a hypothetical hurricane. The simulation allows you to alter different aspects of the coast where the hurricane makes landfall, the tidal conditions during landfall, and the hurricane itself. There are nine different characteristics that you can alter before running the simulation. This lesson will walk you through each characteristic individually to demonstrate its outcome. With the understanding of all of the variables, the user can then create scenarios to simulate using different combinations of characteristics.
Contents |
Initial Set-Up
- Using the directions in CH3D-SSMS Interfaces section in lesson J. Hurricane Charley, navigate to the Hypothetical GUI
- Once there, you should have the option of changing nine different variables before running your simulation
- Set each of the drop down menus to the following:
- Domain type: Large mouth
- Bottom Slope: 1/500
- Tidal amplitude: 50 cm
- Tidal phase: ebb
- Landfall location: Center
- Approach angle: 0
- Forward speed: 20 kt
- Storm category: 3
- Radius to max. winds: 30 miles
- Whenever you run any of the other simulations, use these settings unless otherwise specified
- Click Run Simulation
- Once completed, click view results
- Go back to the hypothetical hurricane page
- Click on the SSMS Inventory link in the bottom left corner
- This shows all of the simulations you have ran
- To view any of the results, press Click here in the View results column
- All of the results will be saved here, so you can go back and view results whenever you want
- You can also open the results in a new window by holding down the shift button and clicking Click here
The following instructions will tell you which simulations to run. You can then open the results in different windows and view the differences. Always use the settings listed above with the one change that is instructed.
Domain Type
For the first simulation you will be working with the shape of the coast at the point of landfall. There are three possibilities given: no bay, bay with a small mouth, and bay with a large mouth. Explain:
- Set the domain type to no bay and run the simulation
- Note the resulting storm surge
- Now, set the domain type to large mouth and run the simulation
- Note the change in resulting storm surge
The change in storm surge is due to...
Bottom Slope
The bottom slope describes the steepness of the sea floor as it approaches the coast. To demonstrate how bottom slope affects surge, you will run the simulation with the minimum bottom available slope and then with the maximum available bottom slope.
- Set the bottom type to 1/1000 and run the simulation
- Note the resulting storm surge
- Now, set the bottom type to 1/100 and run the simulation
- Note the change in resulting storm surge
The slope of the sea floor has a significant affect on the resulting storm surge during a hurricane. When the slope at the shore is more gradual, a rise in water level due to a storm causes water to go much further in. In the given bottom types, a bottom slope of 1/1000 would have water travel 10 times further inland than a bottom slope of 1/100.
Tidal Amplitude and Phase
Landfall Location
The simulation gives the option of having the hurricane make landfall either in the center of the hypothetical coast or to either side. One would not think that the location of landfall would matter in this simulation, but the cyclical nature of the hurricane throws an interesting variable into the storm surge. At one side of the hurricane, the storm is moves inland and carrying water in, while on the other side the opposite occurs. For this reason, you will run a simulation for the hurricane approaching on each side.
- Set the landfall location to left and run the simulation
- Note the resulting storm surge
- Now, set the landfall location to right and run the simulation
- Note the change in resulting storm surge
Approach Angle
There are three possible approach angles to choose: -30, 0, and 30. These reference to the angle measured in degrees clockwise from a hypothetical line perpendicular to the shore and extending from the shore into the water. For reasons similar to that mentioned above in landfall location, the approach angle can affect the storm surge caused by a hurricane.
- Set the approach angle to -30 and run the simulation
- Note the resulting storm surge
- Now, set the approach angle to 30 and run the simulation
- Note the change in resulting storm surge
Forward Speed
The forward speed describes how fast the storm as a whole is moving over water. This is different from the speed of the winds, which determines the intensity of storm. This step will demonstrate the impact of forward speed.
- Set the forward speed to 20 kt and run the simulation
- Note the resulting storm surge
- Now, set the forward speed to 40 kt and run the simulation
- Note the change in resulting storm surge
Storm Category
The category of a hurricane is determined using the Saffir-Simpson Scale. It ranges from Category 1 to Category 5, with 5 being the strongest. The category of a storm is based on the maximum sustained winds, and is a measurement of intensity of the storm. Details on the specific measurements can be found at I. Basic Coastal Definitions. This simulation will show the difference in storm surge due to the intensity of the hurricane.
- Set the storm category to 1 and run the simulation
- Note the resulting storm surge
- Now, set the storm category to 5 and run the simulation
- Note the change in resulting storm surge
As clearly shown in the simulation results, all other factors held constant leave a category 5 storm with a higher storm surge than a category 1. This is the reason that there is a distinct correlation with the category of the hurricane and the amount of the population evacuated. Stronger storms bring in more rain to the area, causing flooding.
Radius to Maximum Winds
The Radius to Maximum Winds (RMS) is the final variable you are allowed to manipulate. This is the measurement from the eye of the hurricane to the strongest winds in the storm, which are usually found near the eye wall.
- Set the RMS to 10 kt and run the simulation
- Note the resulting storm surge
- Now, set the RMS to 30 kt and run the simulation
- Note the change in resulting storm surge
One might think that a larger RMS would cause a larger storm surge. However, as the hurricane reaches peak intensity, the eye wall shrinks, thus resulting in a smaller RMS. Thus, a smaller RMS value leads to a larger storm surge.
Story
Quick Links
