Floodplain Management

Floodplain Strategy

The Corangamite Catchment Management Authority has been working with local communities, Traditional Owners, Local Government Authorities, the Victorian State Emergency Service (VICSES) and other regional agencies to prepare the Corangamite Regional Floodplain Management Strategy.

The draft strategy responds to outcomes of the 2016 Victorian Floodplain Management Strategy, with the aim to:

• Build flood resilience – by sharing information about flood behaviour;
• Reduce flood risks – through emergency management, flood mitigation infrastructure works and activities, and risk management;
• Avoid future flood risks – through land use planning and building controls;
• Manage residual flood risks – through flood insurance, sharing flood risk information, integrated flood emergency management and incident control.
• Protect floodplains for their ecological and cultural values – by integrating the management of flood risks with protecting the environmental and cultural values of natural floodplains.

Development Advice/Permits

The Corangamite CMA work to provide advice for community members, local government and development consultants on floodplain developments.

Developments involving the following areas are what we provide free advice for:

• Floodplain infrastructure
• Works on waterways
• Levee maintenance permits
• Vegetation in waterways

Follow the link below to learn more.

CHALLENGE

Corangamite CMA manages floodplains by assessing any developments that take place on a floodplain or over a waterway while providing free floodplain advice to landholders.

Making sure floodplains are properly looked after ensures that, in the event of a flood, it’s easy to predict the areas in most danger of being damaged.

Key functions of Corangamite CMA in managing floodplains are:

• To find out how far floodwaters are likely to extend and how high they are likely to rise
• To declare flood levels and flood fringe areas
• To declare building lines
• To control developments that have occurred or that  may be proposed for land adjoining waterways
• To develop and implement plans and take any action necessary to minimise flooding and flood damage
• To provide advice about flooding and controls on development to local
  councils, the Secretary for Planning and Environment and the community.

APPROACH

To support this work, we need accurate, up-to-date mapping of the whole catchment in order to model where floodwaters could flow in the event of
flooding.

Throughout 2024-25, Corangamite CMA developed detailed sub catchment mapping which gives a fine-grain view of topography and how water could travel across our landscapes.

This better catchment view was built through regional 5m digital elevation model (DEM), taken from a statewide LiDAR data set (LiDAR being a sophisticated way of measuring ground height relative to sea level).

Hydrological analysis tools were then used to identify catchment boundaries, and further modelling run to simulate different magnitudes of rainfall to confirm the flow paths of water over our catchment terrain.

RESULTS

The enhanced catchment hydrology mapping equips Corangamite CMA to provide more accurate flood advice, and connections between waterways, wetlands and floodplains.

It also better assists us to plan works to improve the
condition of those waterbodies, such as environmental water  releases and refuge pools for native fish.

KEY PARTNERS

This initiative was resourced and delivered internally by Corangamite CMA. The approach and data have been shared with partners including
Barwon Water, DEECA Marine and Coastal team, GORCAPA, and local councils who are excited to utilise the catchment mapping for their own
planning and project delivery.