How to utilize NOAA Atlas 14 storm data in OpenFlows FLOOD?
NOAA Atlas 14 data cannot be consumed directly in OpenFlows FLOOD. The data can be downloaded from the NOAA Atlas 14 website but needs to be prepared in a specific way to be used in OpenFlows FLOOD. The detailed steps for this are available below.
Note: The procedure provided in this tech-note is valid only for users in looking for running design flood simulations, based on statistical data compiled by NOAA, through Atlas 14.
Downloading the Data
1. Go to the NOAA Atlas 14 webpage, and select the correct state where your study / project is located.
2. In data description, Select Data type as Precipitation depth, select Units as Metric and Time series type as Partial duration
Note: For this example we are working in metric units. You can choose “English” units if your dataset corresponds with the same.
3. Select your specific location. You can do this either manually by entering the exact coordinates or if you know the exact station or by an address. Alternatively, you can also use the map to fix your desired location.
4. In the lower part of the webpage, you can now download the statistical precipitation estimates for your location in a CSV file format. By default the field shows Precipitation frequency estimates. Simply click Submit to generate the CSV file, “PF_Depth_Metric_PDS.csv” which you will be prompted to save at a location of your choice.
Preparing the Data
5. Download this file and open it. It can be opened in a spreadsheet application like MS Excel.
6. Copy the data inside the table from the PF_Depth_Metric_PDS.csv file to the “yellow” area of the worksheet called “Alternating Block Template”
The data (in grey) inside the table from the file PF_Depth_Metric_PDS.csv. This is the data to be copied to the worksheet called Alternating Block Template
This is the Alternating_Block.xlsx file with the spreadsheet named Alternating Block Template. In yellow we see the table which needs to filled by copy-pasting the data from PF_Depth_Metric_PDS.csv
7. You should also define the other data in “yellow” cells such as;
a. storm duration: the duration of your design storm
b. hyetograph time step: usually 5 to 10 times smaller than storm duration, ensuring that there is enough rainfall variability where one can clearly see the peak rainfall
c. return period: return period for your design storm
8. If you scroll down the worksheet and you’ll find the computed hyetograph. For OpenFlows FLOOD, we would need to build a timeseries file based in re-ordered interpolated incremental precipitation depths for chosen the time step. Thus the results from columns M and N (cells starting from row 47) are to be chosen. Select this data and copy it to clipboard (CRTL+C).
Using the Data in OpenFlows FLOOD
9. Now we need to copy those results to a rainfall timeseries file in the FLOOD native format. Open OpenFlows FLOOD and your desired workspace (assuming you already have a workspace with an associated domain). For more information on workspaces and domain see here: Creating a new workspace and model domain in OpenFlows FLOOD
10. In the Project tab you will see an Explorer tab. Here, under the Project Tree, expand folder General Data > Boundary Conditions.
11. Right-click on Boundary Conditions and select Create file > Time Series File. Type the selected name for the file (in the example seen in the snapshot below the file was saved with the name “Rainfall_TimeSeriesFile.srm”).
12. Right click on the “Rainfall_TimeSeriesFile.srm” (or the file you just created) and click Open. This would open the file in “File Editor” on the right side.
13. Replace all the data inside the block between <BeginTimeSerie> and <EndTimeSerie> with the information previously copied (in step 8) to the Time Series File. Note that you should also replace the “-“ character in first row of data by the “0.0” value.
14. The first column refers to the amount of time (in units defined by keyword TIME_UNITS) summed to the initial time (defined as SERIE_INITIAL_DATA). Make sure that TIME_UNITS is defined as MINUTES (which is the time unit used in the Alternating_Block.xlsx file with the rainfall data). You can also change the row name from “hours” to “minutes”, although this is merely descriptive and has no impact on the model running, it would be helpful for future reference. Confirm that SERIE_INITIAL_DATA is pointing to the initial time instant of the storm (i.e., the FLOOD simulation must start at a time equal to or later than the SERIE_INITIAL_DATA time instant). Also, the final time instant of your simulation should not be greater than the end of the rainfall timeseries file to be imposed (the end of the rainfall timeseries file is the SERIES_INITIAL_DATA + value of the first column in the last row). As an example, if we define our simulation start time = January 1, 2020 starting at 00:00 and the simulation end time as January 1, 2020 at 05:00, then the rainfall timeseries file should look like this;
In the previous example the simulation would end when it’s still raining (12.667 mm between 270 and 300 minutes after the simulation start), so you won’t see the impact of that rain over the surface, because the model finishes the simulation 300 minutes after the simulation start. Usually you would want to run the design flood model scenario till the point where there’s no rainfall affecting the surface runoff. This can be done by extending the simulation run period. Let’s say you extend the simulation by 120 minutes in this case. This would mean defining your simulation start time as January 1, 2020 at 00:00 and simulation end time as January 1, 2020 at 07:00. In this case, the rainfall timeseries file should be modified with an additional row, looking like this;
15. Save the file (either by right-clicking over the opened file and then clicking “Save”, or by clicking at the icon).
Configuring the Model
16. Next step is to configure the model to read the created time series file. Assuming that a simulation (with atmospheric module included) has already been created, select it, and double-click over Atmosphere_x.dat data file. To understand how to impose time-variable rainfall depth in OpenFlows FLOOD see here: Time series input in OpenFlows FLOOD - imposing time-variable rainfall depth
17. Expand the Precipitation property, and ensure that it is enabled
18. While inside the Precipitation property, expand Values, and configure the following options:
a. Impose field from file: Time Series
b. Filename: (select the path pointing to the created time series file)
c. Data column: 2
d. Map output: select True if you want to output this property to the gridded outputs (HDF5) (be sure that Output > Map Output is set to True)
e. Time Series output: select true in case you want to include this property in a timeseries output file (be sure that option Output > Time Series is set to True, and you have a valid time series location path duly defined).
19. Open Basin_X.dat file from your simulation, and make sure that Atmosphere Module (under Compute Options) is set to True
Your model is now ready for simulation using the rainfall depths imposed from NOAA Atlas 14 data.
Time series input in OpenFlows FLOOD - imposing time-variable rainfall depth
How to incorporate NOAA Atlas 14 rainfall distributions?
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