What is an Index Point?
An index point is the location in a given impact area at which the input relationships are defined (e.g. flow-frequency, stage-discharge). In other words, the index point is the location for which the risk equation is calculated.
What is the Purpose of an Index Point?
How Can I Develop Index Point Data?
Index points may be developed by creating a point shapefile using GIS software, placing points (x-y coordinates) at the index locations.
Working with Index Points in HEC-FDA
Differences Between HEC-FDA Versions 1 and 2
- The primary difference between Versions 1 and 2 is that index points are optional. Index points will only be used to retrieve a graphical stage-frequency function from a hydraulics data set.
- In Version 1, index points were identified using a river station. The use of river stations is how we tricked HEC-FDA Version 1 to consume geographic information. HEC-FDA Version 2 can natively process geospatial data. Hence, index points are identified as x-y coordinates and are imported using the point shapefile.
- Sometimes, the best index points vary by alternative plan. In HEC-FDA Version 2, you can import multiple sets of index points to accommodate retrieval of graphical frequency functions at the correct locations by alternative plan.
Steps for Importing Index Points
- Right click on Index Points under Impact Areas in the Study Tree and select Import Index Points
- Give the set of index points a useful name and description
- Identify the location (path) of the index points shapefile
- Click OK