Mapping of Floodways and Floodplain Development Zones Using 2D Models

Strategic floodplain management benefits from classifying inundated areas into differing degrees of hazard, risk, and suitability for future development. While quantifying hazard and risk is reasonably straightforward, identifying zones for future development is a difficult and contentious process. However, to successfully plan our urban growth on flood liable land, and to minimise flood risks and adverse flood impacts on existing development, identifying these flood development zones in advance is fundamental. Fully 2D hydrodynamic models offer the opportunity to provide more accurate flood impact assessments, and intuitive identification and mapping of these zones, but cannot necessarily apply the conventional approaches used for 1D models.

This paper presents a simple technique using the velocity depth product (VxD) to classify floodways and floodplain development zones using 2D models, and how to easily evaluate the impacts of future works and land-use changes within the floodplain for strategic planning. Examples are discussed and illustrated.