Numerical groundwater modelling as a tool to quantify shallow aquifer water ingress through mining-related open voids
| dc.contributor.advisor | Allwright, Amy | en_ZA |
| dc.contributor.author | van Dyk, George Pieter | en_ZA |
| dc.date.accessioned | 2025-01-03T12:27:04Z | |
| dc.date.available | 2025-01-03T12:27:04Z | |
| dc.date.issued | 2023 | en_ZA |
| dc.description | Dissertation (M.Sc.(Geohydrology))--University of the Free State, 2023 | en_ZA |
| dc.description.abstract | The quantification of water ingress volumes and rates from different aquifer systems through open voids can aid in related studies concerning water quality, decanting potential, and stability evaluations especially in areas where historic mining has played a significant role in altering the groundwater environment. The objective of the research and approach is to evaluate if numerical groundwater modelling can be used as a tool to quantify ingress rates from shallow aquifer systems during rapid recharge events when these aquifer systems become saturated and water seeps through individual mine related open voids on a regional scale, eventually reaching historic mining infrastructure and deeper hard rock aquifers. A case study that focused on the East Rand Basin was used to evaluate if numerical modelling can be used to produce quantified ingress rates from shallow aquifer systems through mine-related open voids. The East Rand Basin has a rich history of mine related activities which still has a large influence on the regional aquifer systems. The research included gathering spatial and site-specific data required to construct and represent a numerical groundwater model in FEFLOW groundwater modelling software. The representative model was used to simulate a scenario that included monthly rainfall records that indicated elevated rainfall events and applied as time dependant recharge to the shallow aquifer systems identified along the Blesbokspruit and associated tributaries. The mapped mine-related open voids that fell within the shallow aquifers systems were assigned as discrete features to represent open voids leading to the mapped historic underground mine workings. The simulation included hydraulic head raises with each consecutive rainfall event to saturate the shallow aquifer systems and the ingress rates were recorded at each individual open void. The outcome of the numerical modelling assessment proved that ingress rates can be quantified with results indicating that a maximum of 12 000 m³/d can flow from the shallow aquifer systems during heavy rainfall events through 33 (out of 69) mapped open voids. The results were compared to a similar study (Waal, 2013), that indicated a good comparison in inflow rates. The model illustrated that roughly 16% of surface-related water (including ingress through shallow aquifer systems) could come from 46% of mine related open voids. Numerical groundwater modelling proved to be a valuable tool to quantify ingress rates from aquifer systems through open voids, however data availability and data quality add major limitations to the result accuracy and model confidence. | en_ZA |
| dc.identifier.uri | http://hdl.handle.net/11660/12906 | |
| dc.language.iso | en | |
| dc.publisher | University of the Free State | en_ZA |
| dc.rights.holder | University of the Free State | en_ZA |
| dc.title | Numerical groundwater modelling as a tool to quantify shallow aquifer water ingress through mining-related open voids | en_ZA |
| dc.type | Dissertation |