Persistent scatterer interferometry to monitor mining related ground surface defomation for data-driven modelling
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The monitorillg, interpretation and prediction of gradual ground surface deformation are critical factors in the understanding of earth systems. In many parts of the world, particul~ly i.., coastal areas where resources are often easily transportable and where steep cliffs allow access to underlying strata, the patterns of natural ground surface deformation are complicated by mining or extraction activities. To accuratelyestilI'..ate the amount of sea-level rise and its total affect on, for example, frequency of flooding or salt-Vv'ater intrusion, the amount of ground surface deformation, either subsidence or uplift, need to be understood in great detail. Ground surface dynamics over an area of contemporary deep mining, is investigated through two research objectives. A feasibility study of conventional InSAR and Persistent Scatterer InSAR (PSI) in a rural setting \VaS carried out. Rural areas are generally avoided for the application of these techniques for the measurement of gradual ground surface deformation due to the lack of coherence between scenes. The results demonstrate that the new PSI technique significantly outperformed conventional InSAR in the detection of gradual ground surface deformation. However, limitations to the technique were identified in the low density and limited distribution of permanent scatterers. The behaviour of the deformation rate over time appears to be biased to a linear trend. Furthermore, in order to understand the link between underground mining activities and local ground surface response a data-driven model has been developed and evaluated. Based on different mining scenarios, this model is able to estimate the total subsidence in a four dimensional space. It \VaS found that local ground surface deformation can be forecasted accurately, based on an angle of draw and four variables. Five key indicators, which are the extent of the disturbed area, the total period of deformation, the peak rate, the moment of the peak rate and the total deformation, are relevant to understand the impact of underground excavations on the surface and to place it in a wider Earth system.