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Welcome to CivilGEO Knowledge Base
Precipitation Type – Inverse Distance Weighted
The Inverse Distance Weighted precipitation type of the Meteorology Data dialog box was originally designed for application in real-time forecasting systems. This precipitation type uses recording gages that are reported at regular intervals such as 15 minutes or 1 hour. It can also use gages that only report daily precipitation totals. This precipitation type can automatically switch from using close gages to using more distant gages when the closer gages stop reporting data.
When Inverse Distance Weighted is selected as the Precipitation type in the Meteorology Data dialog box, the following data panel will be displayed for the Precipitation Data selector.
The following sections describe how to interact with the Inverse Distance Weighted data panel of the Meteorology Data dialog box.
Inverse Distance Weighted Options
This section of the data panel includes the following input parameters.
- Search radius
This field defines the search distance (or radius) that is used to limit the influence distance of precipitation gages. The default value for this field is 621 miles (or 1000 kilometers). The user can click the [Measure] button to measure the influence distance from the Map View. - Use index depth to adjust for regional bias in precipitation
When this checkbox is checked, the Index Depth columns of the Rain Gages and the Subbasin Weighted Nodes data grids are enabled.
Rain Gages
The Rain Gages data grid lists all the rain gages defined in the model and the manner by which they are to be utilized with the Inverse Distance Weighted meteorological method.
- Rain Gage ID
This read-only data column lists all the rain gages defined in the model. - Use Rain Gage
This checkbox option is used to specify that the data defined for the rain gage should be used in the Inverse Distance Weighted meteorological method. - Daily Gage Only
This checkbox option is used to specify that the rain gage only contains daily total precipitation values. If the Use Rain Gage checkbox option of the current rows is unchecked, then the Daily Gage Only checkbox option will be disabled. - Index Depth
This field represents the index value to adjust the gage for regional bias. The average annual precipitation total is often used as the index depth at a rain gage. This data grid column will be disabled when the Use index depth to adjust for regional bias in precipitation checkbox is unchecked.
Subbasin Weighted Nodes
This section and the corresponding data grid list all the nodes defined for each subbasin.
- Subbasin ID
This dropdown combo box is used to select the subbasin to define the weighted nodes to be used in the Inverse Distance Weighted meteorological method. Alternatively, the user can click the [Pick] button to interactively select the subbasin from the Map View. - Node ID
This editable column represents a unique name for the defined weighted node. - Location
This read-only column indicates if the node location has already been placed on the Map View or not. - Node Weight
This spin control field is used to define the node weight and ranges from 0.00 to 1.00. - Index Depth
This column represents the index value to adjust the node for regional bias. Note that this data grid column is disabled when the Use index depth to adjust for regional bias in precipitation checkbox is unchecked.
The [Assign] button is used to select node location on the subbasin from the Map View. The user can also use the [Draw] button to draw the node location on the subbasin from the Map View. The [Delete] button can be used to delete the current row’s weighted node definition. Alternatively, the user can right-click the desired row and select the Delete Row(s) option from the context menu.
