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.