Cliff Instability Areas (ASCCIE) - 2040 - 0.2m SLR

The ASCCIE_2040_02mSLR dataset 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. Further information is contained in the study report "Victorian Coastal Cliff Assessment", Tonkin and Taylor, Sep 2023.\n\nConsolidated shorelines, which include soil and rock cliffs, are not able to rebuild following periods of\nerosion but rather are subject to a one-way process of degradation. ASCCIEs typically have two components:\n• Toe Erosion\nA gradual retreat of the cliff toe caused by weathering, marine and bio-erosion processes. This\nretreat will be affected by global process such as sea level rise and potentially increased soil\nmoisture. Future cliff toe position based on historical erosion rates with a factor applied to\nallow for the effect of future sea level rise.\n• Cliff Instability\nEpisodic instability events are predominately due to a change in loading or material properties\nof the cliff or yielding along a geological structure. In soft cliffs, instability causes the cliff slope\nto flatten to a slope under which it is “stable” (geo-mechanically). Soil cliff slope instabilities\nare influenced by processes that erode and destabilise the cliff toe, including marine\nprocesses, weathering and biological erosion or change the stress within the cliff slope. Most\nof the hard cliffs are stable at very steep angles. Instability events may range from small-scale\ninstabilities (block or rock falls) or discontinuities, to cliff slope instability cause by large-scale\nand deep-seated mass movement. The latter mode of failure in hard cliffs is rare.

ASCCIE_2040_02mSLR数据集是一套包含多组由模拟侵蚀情景生成的空间图层的数字数据集。该数据集推荐应用于维多利亚州海岸线的全州/区域尺度场景。数据的使用需严格遵循随附的《维多利亚海岸悬崖评估》技术报告及专业顾问建议。本产品不适用于单个物业尺度的评估工作。更多详细信息可参阅Tonkin与Taylor于2023年9月发布的研究报告《维多利亚海岸悬崖评估》。

包含土质与岩质悬崖在内的固结海岸线，在经历侵蚀周期后无法自行重建，仅会发生单向的退化过程。ASCCIE数据集通常包含两个核心组成部分：
• 崖脚侵蚀（Toe Erosion）：由风化、海洋侵蚀及生物侵蚀作用共同导致的崖脚逐步后退。该后退过程会受到海平面上升等全球尺度过程，以及潜在的土壤湿度升高的影响。未来崖脚位置将基于历史侵蚀速率，并结合考虑未来海平面上升影响的修正系数进行推算。
• 崖体失稳（Cliff Instability）：偶发的失稳事件主要源于崖体荷载变化、物质属性改变，或沿地质构造发生的屈服破坏。对于软质悬崖，失稳会导致崖坡平缓至符合“稳定”（地质力学层面）标准的坡度。土质崖坡失稳受多种过程影响，包括侵蚀与破坏崖脚稳定的海洋作用、风化、生物侵蚀，或改变崖坡内部应力的作用。多数硬质悬崖在极陡角度下仍可保持稳定。失稳事件的规模跨度较大，从小尺度失稳（岩块坠落或结构面开裂），到大尺度、深层块体运动引发的崖坡失稳。后者这类破坏模式在硬质悬崖中较为罕见。