Modeling Project Part 1
Basic Model Formulation
Dr. Nelson
This assignment will help you review the different models and modeling options studied this semester. It will also help us determine how well the HMS and GSSHA models can be applied to solve the runoff for a watershed for an actual event. It is to be done individually in order to insure that you are all prepared for the final, but it is okay to
You will be provided with the data necessary to develop a model and after you run the simulation we will compare it to observed runoff. After that we will calibrate the model and later on validate it by simulating another storm.
The watershed you will be using is in Wisconsin and part of the Eau Galle basin named 8 Mile Creek. You will perform the analysis with Green and Ampt infiltration for both HMS and GSSHA.
Assignment
Get the following data and perform the tasks listed
DEM data Soil Type data Land use data
Explore and understand the data thoroughly before you proceed to modeling.
Tasks
Delineate the watershed
This is a small watershed compared to what you have been working with before (less than a square mile) and unless you lower the flow accumulation threshold you will not generate stream arcs when you run TOPAZ. So, in the display options under DEM data change the Minimum Accumulation for Display to a smaller number than the default of 1 sq. mile. Your basin should look somewhat like this (note the approximate location of the outlet).
Delineate the watershed, get the land use and soil type coverages mapped based on the GIS data provided and save it as the Base WMS project. This will be the starting point for further modeling with HMS and GSSHA.
Your final HMS model should have single Green and Ampt infiltration model (lumped) that we will define an actual storm (will be provided) for the meteorological model. Use the Clark Method for the transformation. Ultimately you will use this model and optimize (estimate parameters from observed data) for both the Clark and G&A parameters based on peak and volume optimization. For optimization, you will be provided with the observed data set for the real storm and you will compare the outcomes of your model with the real storm.
The following guidelines should be helpful to you
Set up single basin model for HMS. Use following parameters:
Use Green and Ampt Method for infiltration in HMS (use soil type and land use info for the parameters)
Clark Unit Hydrograph method
To make sure things are running define precipitation to be 2.5 inches over 24 hrs with a Type II distribution (we will give you the actual storm later).
You might want to refer to the HMS reference manual (Table 5-2, page 43) for roughness and infiltration (Green and Ampt) parameters. Other references you might need:
Save and Run your HMS model long enough to capture the entire hydrograph.
GSSHA set up
Your final GSSHA model should have 30m grid, Green and Ampt with redistribution infiltration model with a real storm (will be provided). You will have variable roughness and variable infiltration parameters based on land use and soil type data. You will want to create an index map based on both the land use and soil coverages because this is probably more realistic for defining infiltration. Your model should have rivers turned on, redistributed and smoothened.
You already have a lot of experience on GSSHA modeling but it is good to always follow the following sequence of processes for better modeling performance.
Begin with your Base WMS project.
Select the hydrologic model to be GSSHA and initialize the model.
Turn the streams on (check Diffusive wave routing option ON), define the shape (Trapezoidal, 0.7 m deep, 2.4m wide, 4.2 side slope) redistribute the vertices (use a node spacing of at least equal to the grid size) and smooth them. You may also toggle on the display of channel depth and channel flow from output control.
Set up a GSSHA grid of 30 m resolution (which is same as the resolution of the DEM you are using).
Set up Job control parameters.
Develop index maps. At first have auniform index map for uniform roughness.
Use uniform precipitation (you may use any logical rainfall intensity - mm/hr) but do not turn on your infiltration yet. Change the display units to CFS in Job control.
Clean the model up which will run the clean dam and model checker. Fix errors (if any).
Save your project file and run your model and see if there are any puddles or ponding. If so adjust manually using your engineering judgment.
Run GSSHA and view your results (summary file to see if there is still ponding on the watershed), if so you may change the river orientation a little bit or adjust the cell elevation around the ponding areas.
Create three index maps for soil type, land use and both of them combined. Each of these index maps are used to determine the roughness and infiltration parameters. Use the combined (landuse and soil type) index map to define the Green and Ampt Redistributed parameters and landuse index map to define roughness. Do not forget to turn the Green and Ampt with soil moisture redistribution in the Job control under infiltration method.
Run your model and make sure that each component you have entered is working well.
Later you will be provided with the actual rainfall data using which you will run your model.
Finally, you will use the G&A parameters optimized in HMS (where ever possible) and compare your results.
State any assumptions made
Useful links and references:
GSSHA reference Manual - Table 10, page 94
Manning's n values are available here and here.
Do not hesitate to refer to previous assignments.
PS: This is an initial model, we are mostly interested in your "best" effort at getting a result. Don't worry if it is different than another person, what we want is the solution from your best modeling practice. You will see how close to reality you have modeled your watershed later, and it is a good time to judge your/our modeling skills developed throughout this semester. Do not hesitate to ask me or the TA for help.
Using the Real Storm Data
Before your begin this part, you must have your basic HMS (G&A) and GSSHA models running with the specifications described above.
You will now use an actual storm (attached below in this page) and see how your HMS and GSSHA models respond to this storm event. The precipitation data provided here has 15 minutes interval incremental data for a duration of approximately 14 hours and are in mm. Be careful about the units as GSSHA requires metric and you can use both the units in HMS (but use English units for this project).
To define the rainfall data in HMS, you have to select the user hyetograph option and copy and paste the data into the XY series editor of WMS. DO NOT forget to turn on the Incremental Data below the XY series editor. After you have entered the values, you will have to define the rainfall depth in the Meteorological model editor, enter the depth to be 2.36 in.. You do not need dates for HMS so just enter time interval in an increment of 15 minutes.
Similarly, to define the rainfall for GSSHA, you have create a Rain gage coverage, create a gage and enter the gage data. There will be single gage and be careful, in GSSHA you need to define the dates of each increment.
After you run both HMS and GSSHA models summarize the results in the template attached below and email the TA. He will then provide you with the observed flow data for the storm you are simulating. We will use this data in our report to the Corps of Engineers on how well you can use each model to simulate the results.
This is your first shot model and do not worry about getting the model match the observed flow for now. But you still need to make sure that your are getting reasonable results. In the next part of this project, you will compare your results with observed data and do optimization/calibration, but for now we want your best answer.
Get the Storm Data here. You can see the recent precipitation in this basin here.
Get a Template for summarizing your results here.
Submit your simulated results on learning suite.
