Flood Management Plan - Shire of Yarra Ranges

13.1 GLOSSARYBelow are terms defined for the purpose of this Plan.TermDrainage systemDefinitionA series of drains and waterways into which surface andstorm water flows. Features of a drainage system caninclude underground pipe drains, open channels,retarding basins, floodways, waterway improvements,water quality works and environment protectionmeasures. All drainage under 60 ha is maintained andoperated by Darebin City CouncilOverlandfloodingFloodplainInundation by local runoff caused by heavier than usualrainfall. Overland flooding can be caused by local runoffexceeding the capacity of an urban stormwater drainagesystem or by the backwater effects of mainstreamflooding causing urban stormwater drainage system tooverflow.Area of land adjacent to a creek, river, estuary, lake,dam or artificial channel, which is subject to inundationby the probable maximum flood.Natural drainagesystemsFlowpaths which are largely undeveloped by humansources, these include rivers, streams, naturaldepressions and wetlands. All natural systems greaterthan 60 ha are managed by Melbourne Water.Hot spotRunoffFlash floodingA known flood problem area which has a history ofrepeat flooding of a road, crossing or property, oftenhighlighted through anecdotal information and customercomplaints. It is a localised issue which will vary fromcouncil to council.The amount of rainfall that enters the stormwaterdrainage system, (underground pipes, overland flowpaths, floodway and waterways) after losses such asinfiltration has been taken into account.Sudden unexpected flooding caused by local heavyrainfall or rainfall in another area. Often defined asflooding which occurs within six hours of the rain whichcauses flooding.Melbourne Water Shire of Yarra Ranges Flood Management Plan 69