FENDER GEOPHYSICS FREQUENTLY HELPS GOVERNMENT ORGANISATIONS, MINING COMPANIES AND OTHER COMMERCIAL ENTITIES SEARCH FOR GROUNDWATER.
Many of our clients are in remote areas and rely on groundwater for their operational needs. Town water is either limited or non-existent and mines and other commercial activities that are without economical sources of water are not viable. Fender’s near-surface geophysical survey techniques can be used to find and economically access groundwater and ensure water security for these operations.
Electromagnetic (EM) and resistivity methods are commonly used for the detection of aquifers. These methods can be used on their own or combined. Buried river channels are usually good targets as groundwater sources. The channels commonly occur from tens to hundreds of metres depth and there is usually no evidence of the channel at the surface. Where palaeochannels are eroded into bedrock they can also be delineated by seismic refraction and MASW. Geophysical surveys find, and provide insights into, aquifer geometry and character and subsequently make choosing the location of groundwater bores much more successful.
Identifying fractured rock aquifers
Ground magnetic surveys can assist with identifying fractured rock aquifers and are quicker to deploy than a resistivity or EM survey. It assumes the magnetic response is mostly related to the basement rock and not the sediments above. Groundwater can accumulate in bedrock fractures where there is space into which it can seep rather than lying within discrete units of porous sediments. A magnetic map will highlight discontinuities in the basement. These discontinuities can be interpreted as fractures and targeted for drilling.
Mapping subsurface geology
Geophysical surveys can provide broad 2D and 3D maps of subsurface geology based on borehole lithology data. Mapping lithologies between boreholes is commonly required to understand aquifer geometry, however, there is little certainty when using only lithology data from bores. Linking geology data from boreholes to geophysical data is a rapid way to map subsurface lithologies (in 2D and 3D) and provide insights into aquifer characteristics and rock stratification.
Contaminant seepage and drainage
Geophysical surveys are a good way of extrapolating groundwater and geological information between bores. Seepage from tailings dams and acid rock drainage are important management concerns on mine sites. Contaminants can make their way into groundwater which makes it unusable. The remediation of mine sites may include the installation of ground water bores around the perimeter of the mine area to monitor the contamination of the groundwater. Drilling bores is expensive which limits their number and geophysical surveys lead to more spatially extensive insights into groundwater pathways and their possible interaction with surface contaminants.
The worldwide reliance on groundwater justifies the effort and expense in identification and delineation of ground water resources. The employment of geophysical techniques in both ground water mapping and water quality assessment has increased substantially in the past decade. Technological advancements enable the detailed mapping of water conduits and reservoirs by contrasting subtle changes in subsurface conductivity due to water seepage. Fender conducts cost-effective ground water surveys to suit your needs in terms of depth, area, and required resolution of data.