Statistics

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Statistics

The Statistics  tool allows the user to process a number of flood surfaces to determine the likelihood that a certain hydraulic condition (peak) will be met. For example, what is the Annual Recurrence Interval (ARI) of each part of the floodplain being inundated?

To calculate such a surface, interpolation between surfaces of different magnitudes is carried out to find where the criteria is met. Consequently, the algorithm assumes a montonically varying magnitude between probabilities for any given location (ie the water level for the 100yr flood is greater than the 50yr flood and less than the 200yr flood). Care should be taken when using the tool on parameters that do not display such behaviour.

This tool will provide a probability surface. To determine the probability of discrete locations (eg properties, roads, infrastructure etc) being inundated, use the Determine Probability of Inundation tool.

Any hydraulic parameter contained in the surface files can be analysed, including processed parameters from the Parameter Queries menu.

 

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To use the tool:

1) Specify the surfaces from the current project to include in the calculation.

2) Specify the ARI for each of the surfaces

3) Specify the hydraulic condition to use in the analysis

4) Specify the interpolation method between surfaces

5) Specify the output format

6) Run the tool clip12178

Note that for correct interpolation, each surfaces should be stretched to the extent of the peak surface.