Hydrogeological response to mining

Systematic underground hydrogeological monitoring and measurements have to be carried out along with piezometer, extensometer and water inflow monitoring data during mining in order to accurately assess the impact of underground extraction.

On the basis of field monitoring and measurement results, site hydrogeological characterisation has to be undertaken and in situ hydrogeological models have to be established for the underground workings. The team has been involved in using field data and large scale coupled mechanical and fluid flow numerical models to understand the groundwater flow mechanics for the mines. The analysis has been done in local and mini-regional scale, incorporating various underground workings and ecological bodies.

The figure below shows an example of groundwater pressure head drops estimated for one of the mini-regional scale models conducted using 3D continuum numerical code. The model uses a 30km by 30km regional area with multiple underground excavations areas. The available data from 1980 AD was used to calibrate and validate the model and predictions were made up to the distant future. The prediction was performed for groundwater depressurisation and recovery. The model used mining induced conductivity changes, rainfall, evapotranspiration, rivers, alluvium, ocean, bore extraction and hydrogeology.