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NOHRSC Technology > NOHRSC GIS Applications > Unit Hydrograph

Unit Hydrograph Operational Notes

IHABBS and Unit Hydrograph

IHABBS is important to the Unit Hydrograph application in that it creates the basin boundaries that are used by the latter program. Unit Hydrograph takes the geometry created by IHABBS and constructs a unit hydrograph by routing water over the surface of the basin.

However, the resulting hydrograph can be rendered inaccurate if the basin geometry is edited after the hydrograph is generated. Deleting the basin will obviously affect the relevance of the hydrograph as well. If the user makes changes to the basin layer that impacts generated hydrographs, IHABBS will flash a warning screen before the layer can be saved. This dialog will show the altered basins and the hydrographs that will be affected. It is then up to the user to recalculate those hydrographs in the Unit Hydrograph program.

The user can update the hydrograph by opening the hydrograph from the altered basin layer. The Recalculate option will update the unit hydrograph. Saving the changes will complete the updating process.

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Page last modified: Nov 15, 2005 - cloud
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