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Download page Task 1 – Define MetVue Alternatives.
Task 1 – Define MetVue Alternatives
Within the CAVI window, right-click on the QPF MetVue Alternative and select Edit MetVue Alternative.
The MetVue Alternative Editor for the QPF alternative will open.
Notice the two tabs within the window for both Input and Output settings. The Input Settings tab lists each Map Window that is present within the MetVue alternative.
Define Alternative Input Settings
Select the checkboxes designating each dataset as Lookback or Forecast.
The Snow Water Equivalent (SWE) data for this watershed comes from the National Operational Hydrologic Remote Sensing Center (NOHRSC) Snow Data Assimilation System (SNODAS) and is only available at a daily timestep at 0600 GMT. The HEC-HMS model must then start at 0600 for the model to read the initial SWE content.
A workaround to ensure the HMS model has initial SWE values at any starting timestep is to set a -1 day offset to start SWE data processing within MetVue the day before the start of the forecast. This offset can be specified within the Alternative Editor Input Settings as demonstrated below.
Note that a similar approach is required if you are using the HMS Gridded Hamon ET method, the Observed Temperature must have a Start of Simulation (SoS) offset of -1 and an End of Forecast (EoF) offset of +1 day for the forecast temperature.
Set a -1 day offset to the SWE data lookback by selecting Days from the interval drop down and entering -1 into the SoS (Start of Simulation) Offset column. No offsets are required for the other datasets.
Set the Input Data pathnames for each data type by highlighting the data type up above and selecting the Browse... button, starting with the FcstPrecip dataset.
The Select Time Series Path dialog box will open. Select the Open (
) button and navigate to the sample data dss file at: C:\Workshops\MetVue\HEC-MetVue_CWMS_SetupOrientation\HEC-MetVue_CWMS_SetupOrientation_Start\EauGalleCAVI\watershed\EauGalleRiver\metvue\data\forecast.dss
For FcstTemp, select the /SHG/EAU GALLE RIVER/PRECIP///WPC-QPF-2.5KM/ pathname by double clicking the pathname or highlighting the pathname and selecting Set Pathname.
The Alternative Editor will then populate the Input Data portion with the appropriate pathname information.
Browsing to the sample data and selecting pathnames directly from the dss file can prevent common mistakes that can happen when manually typing in pathnames (such as typos or incorrect durations).
Repeat the steps above for each Map Window with the following pathnames:
| Map Window | Pathname |
|---|---|
| FcstTemp | /SHG/Eau Galle River/AIRTEMP///MBRFC-KRF-FCT/ |
| ObsPrecip | /SHG/Eau Galle River/PRECIP///NCEP-STAGE4/ |
| ObsTemp | /SHG/Eau Galle River/AIRTEMP///NDGD-RTMA/ |
| SWE | /SHG/EAU GALLE RIVER/SWE///SNODAS-INTERP/ |
Select Apply once all pathnames have been specified to save the Input Settings.
Define Alternative Output Settings
Select the Output Settings Tab to define the MetVue outputs.
The Eau Galle River watershed HMS model relies on MetVue to combine the Observed and Forecast precipitation and temperature data into a single gridded dataset.
It also uses MetVue to create hourly SWE grids so that the HMS model has an initial SWE condition at any hour of the day (since the raw SNODAS SWE has a single daily timestep of 0600 by default).
MetVue will also write out basin-average time series of each output product. This can be useful for quickly visualizing volumes within certain subbasins over time.
A summary of MetVue Outputs for the Eau Galle Watershed includes:
- Precipitation: Hourly grids and basin-average time series
- Temperature: Hourly grids and basin-average time series
- SWE: Hourly grids and basin-average time series
Select the Add button to add an output dataset.
A new dataset (New Data Set 1) will be added to the Output Dataset Selection Window.
Rename the new dataset to Precip and confirm the Parameter type is set to Precip and the Lookback and Forecast Maps are selected appropriately.
Confirm the Output Settings look correct.
Output Settings
The default output settings of a 1Hour time interval and PER-CUM parameter type are appropriate for precipitation output.
The Output Extents are automatically set to the basin-average shapefile (in this case, the hmsBasinsEauGalle.shp). Setting the output extents provides an opportunity to limit the output grid extents if the original input grid extents were much larger than necessary for the watershed. In this case, the Eau Galle River input grids have already been clipped to the watershed by cumulus, but it is still okay to accept the default output extents setting here.
Check the box next to Save Modified TINs to DSS and set the B-Part to Eau Galle River.
Selecting this option will write out the dataset as gridded dss files with the pathname: /SHG/Eau Galle River/Precip//// where the F-Part will become the QPF MetVue alternative key within the forecast.
Check the box next to Generate Time Series, select Write to Forecast DSS and ensure the Sub-basin Name Column is set to name (the dropdown list offers options from the shapefile's attribute table).
Select Apply to save the new Output settings.
Repeat the steps above to create the Temperature and SWE output with the following settings:
Note that the Temp and SWE output parameter type is set to INST-VAL which is more appropriate for these type of data than the PER-CUM used for Precip.
Since there is no forecast SWE available, the Forecast Map is set to the Default Value (which for SWE in this case is Zero). The Default Value can be updated by selection the Options button if needed.
Define Remaining Alternative Settings
Once all of the QPF alternative inputs and outputs have been defined, follow the same steps to define the NoQPF alternative settings.
Recall that the NoQPF alternative does not include a FcstPrecip Map Window, therefore the NoQPF Precip output for the Forecast Map Window will be set to Default Value which is Zero in this case.
The input and output settings for both the QPF and NoQPF Alternatives have now been defined and Model Alternative Keys can be set (Part B, Task 2).
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