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Flood Magnitudes for Small Basins

This application provides estimates of flood peak discharge in cumecs (m3/s) across New Zealand using different methods. For some methods calculations are restricted to river reaches with catchment areas smaller than 30 km2.

Enter or select a river reach from the map by zooming and panning to the point of interest (zooming in close enough reveals reach IDs on the map). For the Rational Method, users must enter a coefficient value (C) they consider suitable for the catchment.

Then click “Generate Flood Magnitudes”.

Find location on map


Return interval [years] 5 10 20 50 100 1000