A predictive GIS methodology for mapping potential mining induced rock falls

Coal mining operations impact on various types of natural features, including cliff lines, steep slopes and natural watercourses. The introduction of longwall mining has led to subsidence depression due to the changing geometry of the mined out area. Subsidence can destabilise cliff lines and increase the probability of rock falls and cliff collapse. The current process for managing subsidence in New South Wales (NSW) involves the preparation of a Subsidence Management Plan (SMP). One approach for managing the results of subsidence is to develop pre-mining methodologies for assessing potential mining impacts. This thesis deals with a quantitative Geographical Information Systems (GIS) based methodology for mapping potential mine subsidence-induced rock falls along cliffs and steep slopes along the Nepean River Gorge. The proposed methodology is developed using Weights-of-Evidence (WofE) method within a GIS framework to derive a probabilistic model of rock falls associated with mining-induced subsidence. The thesis uses ten (10) known mining-induced rock falls associated with longwall workings along the Cataract River to evaluate the impact of restricting mining to a region greater than 50 m of the Nepean cliffs. The results represent significant reduction of probabilities of rock fall occurrence when mining is conducted in this way.