Title

Cliff Instability Areas (ASCCIE) - 2100 - 1.1m SLR 

Alternate title

ASCCIE_2100_1_1mSLR 

Resource Type

Dataset  

Purpose

Regional / state-wide scale 

Time period

2024-02-272024-02-27 

Spatial representation type

Vector  

Horizontal Accuracy

10m  

 

Maintenance and update frequency

As needed  

Title

File geodatabase, shapefile 

Topic category

• Environment
• Oceans

Classification

Unclassified  

Statement

Areas susceptible to coastal cliff instability and/or erosion (ASCCIE) 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. A LiDAR survey of the Victoria region was undertaken between 2006 and 2009 by the Department of Sustainability and Environment and provides full coverage of the entire Victorian coastline. This LiDAR was processed into a Digital Elevation Model (DEM) surface and has a grid resolution of 2.5 m x 2.5 m. In addition to the 2006-2009 LiDAR, there is more recent higher resolution LiDAR coverage of localised areas within Victoria. These additional data sets are as follows: • Victorian Coastal LiDAR Level 3 Classification (Port Phillip Bay & Western Port and East & West Victoria). This dataset consists of a reprocessed DEM from the original 2006-2007 LiDAR data. • 2017-2018 Greater Melbourne LiDAR. This dataset consists of 1m DTM (Digital Terrain Model) of 12,000 km2 of coast across the Greater Melbourne region. • 2019-2020 Great Ocean Road Elevation and Photography. This dataset consists of a 0.5m grid resolution DEM. • 2020-2021 Bayside Yarra LiDAR. This dataset consists of a DEM with data captured at 24 pts/m2. All of these LiDAR datasets were used in combination for the entire cliffed shoreline, with the highest resolution and most recent LiDAR data being used for each location. Figure 3.2 shows the LiDAR dataset extents that have been used for this study. 3.1.2 Coastal transects In addition to the LiDAR DEMs and DTMs described above, coastal transects were provided by DEECA for the full length of the Victorian coast. These transects are 400 m long and spaced at 30 m increments along the shoreline (see example of transects in Figure 3.1). For this project some transects (e.g. at very high cliffs) have been extended to capture the entire cliff profile. Further information in the study report "Victorian Coastal Cliff Assessment", Tonkin and Taylor, Sep 2023 

Description

Modelled dataset based on Lidar data, coastal transects and modelled coastal water / tidal levels 

Use limitation

Unknown 

Classification

Unclassified