The Victorian Coastal Cliff Assessment - Instability Areas (ASCCIE) is a digital dataset consisting of multiple spatial layer outputs from modelled erosion scenarios. The dataset is recommended for use at the statewide / regional scale along the Victorian coastline. Application of the data should be guided by the accompanying Victorian Coastal Cliff Assessment technical reports and expert advice. The product is not suitable for individual property scale assessments.
Consolidated shorelines, which include soil and rock cliffs, are not able to rebuild following periods of erosion but rather are subject to a one-way process of degradation. ASCCIEs typically have two components:
• Toe Erosion
A gradual retreat of the cliff toe caused by weathering, marine and bio-erosion processes. This retreat will be affected by global process such as sea level rise and potentially increased soil moisture. Future cliff toe position based on historical erosion rates with a factor applied to allow for the effect of future sea level rise.
• Cliff Instability
Episodic instability events are predominately due to a change in loading or material properties of the cliff or yielding along a geological structure. In soft cliffs, instability causes the cliff slope to flatten to a slope under which it is “stable” (geo-mechanically). Soil cliff slope instabilities are influenced by processes that erode and destabilise the cliff toe, including marine processes, weathering and biological erosion or change the stress within the cliff slope. Most of the hard cliffs are stable at very steep angles. Instability events may range from small-scale instabilities (block or rock falls) or discontinuities, to cliff slope instability cause by large-scale and deep-seated mass movement. The latter mode of failure in hard cliffs is rare.
The product is an update to the Victorian Coastal Cliff Assessment, Stage 1. Included datasets for Stage 2a supersede the Stage 1 outputs. The Stage 2a project report should be read in conjunction with the Stage 1 report. Application of the data should be guided by the accompanying "Victorian Coastal Cliff Assessment, Stage 2a technical report" (Tonkin & Taylor 2025) read in conjunction with the Stage 1 technical report, combined with appropriate expert advice.