Flood Extent 1% Annual Exceedance Probability (AEP)

dataset: FLOOD_EXTENT_1PC_AEP
Annual Exceedance Probability (AEP) is the probability of a flood event being equalled or exceeded within a year. A 1% AEP means there is a 1% chance (or a 1 in 100 chance) of a flood event of that size occurring or being exceeded in any given year. This is also sometimes referred to as a "100 year Annual Recurrence Internal (ARI)” or "1 in 100 year" flood event. The Victorian statewide layer of 1% AEP Flood Extent has been compiled from data maintained by Victoria's 9 Catchment Management Authorities (CMAs) and Melbourne Water. Each of these authorities maintain a layer of Regional 1%AEP Flood Extent, and these have been combined into a statewide layer by DEECA with their permission. Some CMAs maintain separate layers of 1%AEP for riverine flooding, coastal flooding and stormwater (urban rainfall driven) flooding. This statewide layer merges the different flooding types into a single layer, where they exist. Flood modelling is being continuously updated across Victoria. Flood extent layers will be updated periodically as new local flood studies are completed and the CMAs and Melbourne Water update their Regional 1%AEP Flood Extent layers. The statewide layer is updated approximately quarterly, when the CMAs and Melbourne provide updates to DEECA. The data represents flooding risk under current climatic conditions. It does not include any allowances for sea level rise, storm surge or changes to rainfall patterns because of climate change. Floods by their nature are rare and unpredictable, they tend to occur randomly and the periods between floods of a given size are usually random. All floods are different, potential future floods are described by their likelihood of occurring. If regions are shown as flood free in this layer, it does not necessarily mean they are entirely flood free. Floods greater than a 1%AEP magnitude can and do occur. Other locations may not have flood studies or historical flood information available at this time. Contact the relevant Catchment Management Authority or Melbourne Water for the best source for flood information to inform property purchase, development or use decisions.
 
Citation proposal Citation proposal
(1980)

Flood Extent 1% Annual Exceedance Probability (AEP)

Department of Energy, Environment and Climate Action
 

Simple

 
 

Description

Title
Flood Extent 1% Annual Exceedance Probability (AEP) 
Alternate title
FLOOD_EXTENT_1PC_AEP 
Purpose
This data can be used to understand the distribution of known, mapped, flood risk in Victoria. This data should not be used for planning or in an emergency. The web service associated with this data is used in a number of public facing and internal government web mapping applications. 
Status
On going  
 
 

Temporal

 
 

Spatial

 
 

Maintenance

Maintenance and update frequency
Quarterly  
 
 

Format

Title
Other 
 
 

Contacts

  Point of contact

Cited responsible party  

No information provided.

Cited responsible party  

No information provided.
 
 

Keywords

Topic category
  • Environment
  • Inland waters
  • Climatology, meteorology, atmosphere
 
 

Resource Constraints

Use limitation
Unknown 
Classification
Limited Distribution  
 
 

Lineage

Statement
Victoria's 9 Catchment Management Authorities (CMAs) and Melbourne Water (MW) each maintain layers of Regional 1%AEP Flood Extents (covering their regional boundary). Some CMAs and MW maintain separate layers for riverine, coastal and stormwater (drains) flooding. The CMAs/MW create the regional layers based on a compilation of calibrated flood models, estimates based on historical flood extents, comparison to LiDAR elevation models, and or rough (un-calibrated) modelling. Where multiple flood studies have been delivered for an area, the authority will use the most recent and accurate data. Generally speaking most high risk populated areas of the state will have some level of calibrated flood modelling completed. Areas where flood risk is low and are non-urbanised, may not have accurate or any modelling. The CMAs and Melbourne Water share the regional extent data with the DEECA FloodZoom team. Updates are provided when new data exists, and are processed by DEECA approximately quarterly. DEECA publishes the combined data as an Esri Vector Tile Service for consumption by partner platforms including VicPlan and Emergency Management web maps. 
 
 

Metadata Constraints

Use limitation
At this time only available as web service from DEECA. 
Classification
Unclassified  
 
 

Quality

Attribute Quality
Positional Accuracy
Conceptual Consistency
Missing Data
Excess Data
 
 

Acquisition Info

 
 

Raster Data Details

 
 

Point Cloud Data Details

 
 

Contour Data Details

 
 

Survey Details

 
 

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