Precipitation Type - Rain Gage - Knowledge Base on CivilGEO

The Rain Gage precipitation type of the Meteorology Data dialog box is designed to work with time series recording and single value recording precipitation gages. Time series recording precipitation gages typically measure precipitation as it occurs and then the raw data is converted to a regular time step, such as 15 minutes or 1 hour. Single value recording precipitation gages only record the total storm depth. The user can choose from different methods to develop the weights applied to each rain gage when calculating the hyetograph for each subbasin. For increased flexibility, the total storm depth and the temporal pattern are developed separately for each subbasin.

When Rain Gage is selected as the Precipitation type in the Meteorology Data dialog box, the following data panel will be displayed for the Precipitation Data selector.
Rain Gage is selected as the Precipitation type

The following sections describe how to interact with the Rain Gage data panel of the Meteorology Data dialog box.

Rain Gage Specifications

This section of the data panel includes the following options.

Define index depth to adjust for regional bias in precipitation
This checkbox option allows the user to adjust the regional bias in the rainfall depth to be used for each rain gage and subbasin. This is helpful when there are regional trends in precipitation patterns. Using this option requires the specification of an “index” value for each precipitation gage and each subbasin. The average annual precipitation total is often used as the index at a rain gage, and the estimated average annual precipitation over a subbasin area is often used as the index for a subbasin. Alternatively, the monthly average values may be used at each rain gage and subbasin. The index values are used to adjust the precipitation data for regional trends before calculating the weighted depth and weighted timing.
Define rain gage total depth (override)
This checkbox option allows the user to override the precipitation depth at each rain gage. Without this override, the total depth defined at a rain gage is the sum of the values in the rain gage time series. With this override, the values in the rain gage time series are proportionally adjusted to have a sum equal to the specified total rain depth.

Subbasin Index Depths (Optional)

This optional section contains a data grid that is used to define an Index Depth for each subbasin. This section is disabled if the Define index depth to adjust for regional bias in precipitation checkbox is unchecked. For the Index Depth option to work, the user must enter an index value for each subbasin and rain gage.
Rain Gages precipitation panel - Subbasin Index Depth (Optional)

Time Series Rain Gage Specifications (Optional Override)

This section contains a data grid that is used to define a total depth and index depth for each rain gage defined within the Meteorological Model for the current scenario. This section is disabled if both the Define rain gage total depth(override) and the Define index depth to adjust for regional bias in precipitation checkbox options are unchecked.
Rain Gages precipitation panel - Time Series Rain Gage Specifications (Optional Override)

Single Value Rain Gage Specifications

This section contains a data grid that allows the user to manually define single value rain gages. In the Single Value Rain Gage ID column, the user can manually enter a unique ID for a single value rain gage.
Rain Gages precipitation panel - Single Value Rain Gage Specifications

Subbasin Weighted Rain Gages

This section allows the user to define how much weight each rain gage has for each subbasin.
Subbasin Weighted Rain Gages

Select Subbasin ID
This dropdown combo box lists all the subbasins contained within the scenario. If a subbasin is currently selected on the Map View, it is shown selected in this entry. Otherwise, the last selected subbasin is shown selected. The [Pick] button allows the user to manually select the subbasin from the Map View.
Rain Gage ID
This read-only data column lists all the rain gages (i.e., time series and single value) defined in the scenario.
Rain Gage Type
This read-only field lists the type of rain gage that is defined. It is either Time Series or Single Value.
Use Rain Gage
This checkbox entry allows the user to specify whether to use the rain gage for the selected subbasin or not.
Gage Depth Weight
This spin control allows the user to define the depth weight for the rain gage. Note that this cell is disabled if the Use Rain Gage checkbox is unchecked.
Gage Time Weight
This spin control allows the user to define the time weight for the rain gage. This cell is disabled for single value rain gages or if the Use Rain Gage checkbox is unchecked.