Definitions

Overland flooding happens when heavy rain causes water to flow over the ground, usually because the drainage system can’t handle the volume. This is different from riverine flooding, which happens when a river or creek overflows its banks.

Also called a 'rainfall-runoff model', it models storms and determines how much water is coming off the catchment. Hydrologic models turn rainfall into flows.

Hydraulic models (such as TUFLOW) are used to turn flows into a range of metrics including depth, levels, velocity and hazard.

AEP means Annual Exceedance Probability. A 1% AEP event has a 1% chance of occurring in any given year, and is commonly used for design and planning purposes.

Probable Maximum Flood is the largest flood that could conceivably occur at a particular location. The PMF defines the extent of our flood prone land, i.e. the floodplain

Flood Planning Level is the combination of flood levels and freeboards selected for planning purposes. Different FPLs may apply to different types of development and are used for setting minimum floor levels or flood proofing levels.

The flood-related functions of floodways, flood storage and flood fringe within the floodplain, also referred to as 'Hydraulic Categories'.

Flooding that has the potential to cause harm or conditions with the potential to result in loss of life, injury and economic loss.