In GeoHECRAS, the Lookup Rainfall command retrieves rainfall (depth or intensity) data for any location within Austria, Canada, Germany, and the United States.
Follow the steps below to use the Lookup Rainfall command:
- From the Input ribbon menu, click the Meteorology Data dropdown menu and select the Lookup Rainfall command.
- The Lookup Rainfall Depth dialog box will be displayed.
Note that the Meteorology Data dropdown menu will only be enabled for unsteady flow data. Otherwise, this dropdown menu will be disabled. To enable it, select the Unsteady Flow Data radio button option in the Scenario Manager dialog box.
The following sections describe how to interact with the Lookup Rainfall Depth dialog box.
Location Selection
This section allows the user to select the location from which the rainfall data are to be retrieved.
The following options are available in this section:
- Centered on current view extents
If this radio button option is selected, the software will pick the central location of the region displayed in the current Map View extents to retrieve rainfall data.
- Centered on HEC-RAS model extents
If this radio button option is selected, the software will pick the central location of the HEC-RAS model defined in the current scenario. If no HEC-RAS model is defined, this option will be disabled (i.e., grayed out).
- Select location
This radio button option allows the user to pick the desired location from the Map View interactively by using the [Pick] button. The address of the selected location will be displayed in the read-only field next to this option. The latitude and longitude values for the selected location will be displayed in the Latitude & longitude fields. The user can click the [Clear] button to clear the defined location and redo the entire process.
Note that if the user selects either the Centered on current view extents or the Centered on HEC-RAS model extents option, the software will display the information of the selected location after successfully retrieving the rainfall data.
Perform Rainfall Lookup
Once the project location for which the rainfall data are to be retrieved is selected, the user can select the precipitation data type and precipitation data sources available for the selected project location.
The following options are available in this section:
- Precipitation data type
This dropdown combo box entry lists the precipitation data types to be used for retrieving rainfall data. The following entries are available:
- Rainfall Depth
- Rainfall Intensity
Note that the section header name changes based on the precipitation data type selected by the user.
- Precipitation data source
This dropdown combo box entry lists the precipitation data sources available for the selected location.
The following precipitation data sources are available:
- Austria – Bundesministerium Wasserwirtschaft eHYD Data Service
- Canada – Environment Canada & Ontario Ministry of Transportation
- Canada – Ontario Ministry of Transportation
- Germany – Deutscher Wetterdienst – Klima und Umwelt
- USA – ISWS (Illinois) Bulletin 75 (PFDS) Precipitation Frequency Data Server
- USA – NOAA Atlas 14 (PFDS) Precipitation Frequency Data Server
- USA – NOAA Atlas 2 (PFDS) Precipitation Frequency Data Server
- USA – NRCC (Northeast Regional Climate Center) PFDS
- USA – SUDAS (lowa) Bulletin 71 (PFDS) Precipitation Frequency Data Server
Note that the specific precipitation data source entry will be displayed based on the selected project location.
Retrieving Rainfall Data
Once the precipitation data source is selected, click the [Retrieve] button to retrieve the rainfall data for the selected location.
Note that the coverage area shown below is current as of April 2023. However, this coverage area will continue to increase as more states are processed.
If the selected location is not within the coverage area available, the software will display the following informational dialog box.
After successfully retrieving the rainfall data, the software populates the data in the table provided under the Frequency (Years) subsection. This table displays the rainfall depth/intensity values for various storm durations for 1, 2, 5, 10, 25, 50, 100, 200, 500, and 1000-year storm events.
In addition, the user can right-click anywhere in the data table to display a context menu with commands for copying rainfall data to the Windows clipboard or exporting the data in different file formats.