Flood Tool

The Flood tool assesses the land area covered by water in different water flooding scenarios. The result of the flood analysis process is a set of polygons showing the flooded areas.

Analysis can be performed based on either of the following scenarios:

§ Single Instance - Water level rises once (initial water level set by user).

§ Continuous Rise - Water level rising at a constant rate over a certain period of time (rate of rise and rise interval set by user).

Using the Flood Tool

To use the Flood tool:

1. On the Analysis tab, in the Terrain Analysis group, click Flood.

2. In the property sheet, in the Sample Interval field, enter the desired distance between sample points.

3. In the property sheet, in the Scenario Type field, select a scenario:

§ Single Instance - Water level rises once.

§ Continuous Rise - Water level rising at a constant rate over a certain period of time.

4. If you selected Single Instance in step 4, in the Water Level Rise field, enter the initial water elevation in meters.

5. If you selected Continuous Rise in step 4, set the following parameters in the property sheet:

§ Water Rise Rate

§ Start Time

§ End Time

§ Time Sample Interval

6. In the 3D Window, click a point to mark the center of the circular area to be analyzed.

7. Drag the mouse to set the required radius size and click again.

Note: If the Sample Interval (See below in property sheet) is smaller than necessary for an accurate assessment, a dialog is displayed asking if you want to increase the Sample Interval to a recommended value. Click Yes to increase the size, or No to keep the sample size as is.

The result of the flood analysis process is a set of polygons showing the flooded areas.

Flood Analysis Property Sheet Parameters

Parameter	Description
Sample Interval	Enter the desired value for the resolution of the measurement. This value represents the distance between terrain sample points. The smaller the sample interval, the more accurate the calculation, but the longer it takes to calculate.
Scenario	Select a scenario: § Single Instance - Water level rises once. § Continuous Rise - Water level rising at a constant rate over a certain period of time.
Water Level Rise	This field is only enabled when Single Instance is selected in the Scenario field. Enter the initial water elevation in meters.
Water Rise Rate	This field is only enabled when Continuous Rise is selected in the Scenario field. Enter the rate (meters/hour) that the water is rising.
Start Time	This field is only enabled when Continuous Rise is selected in the Scenario field. Select the time and date that the water level begins to rise.
End Time	This field is only enabled when Continuous Rise is selected in the Scenario field. Select the time and date that the water level stop rising.
Time Sample Interval	This field is only enabled when Continuous Rise is selected in the Scenario field. This value determines how many samples are taken between the Start Time and End Time. The smaller the sample interval, the more accurate the calculation, but the longer it takes to calculate.