Mapping Water Resources

The SkyTEM system is an innovative and technologically advanced airborne geophysical system specifically designed to mapping water resources. This unique technology, capable of mapping the top 500 metres of the Earth in fine detail and in 3 dimensions, was conceived and developed in Denmark, a country with a reputation for environmental care and R&D.

SkyTEM has helped geological organizations and government water agencies on seven continents unearth a wealth of information about their aquifers and aided in their understanding of how geology and mankind can affect, and be affected by, groundwater resources.

Drillling boreholes is not enough for mapping water

In most parts of the world groundwater mapping is based only on one data source – drilling information. A 6 inch borehole represents less than one millionth of acre. This 6 inch borehole will provide precise information about the geology  immediately in the vicinity of the hole, but any assumptions made about the surrounding geology is a leap of faith or at best a guess. Drilling boreholes can be expensive particularly when insufficient information is available to determine where to drill and how deep to drill for water. If a large area is being studied, budgets may only allow for limited drilling so selection of where to drill is crucial. Also, access to some areas can be difficult and expensive if the terrain is remote, rugged or heavily vegetated. Limited drilling is often the only option cosidered and low borehole density can result in uncertainties and low confidence levels in geologial interpretations and hydrogeological models.

The SkyTEM airborne method of mappping quickly and economically delivers accurate subsurface data from which location of and depth to aquifers can be revealed.

Read more about the SkyTEM method for mapping water resources in the brochure here.

SkyTEM for mappping water

Geoscience BC report from SkyTEM Peace Project survey

Information presented in the report is the result of the Peace Project, a Geoscience BC-funded project focused on mapping and assessing groundwater in the Peace Region of British Columbia. The report presents data from a SkyTEM airborne electromagnetic (AEM) geophysical survey that was employed to map the hydrogeology in the Peace Project area.

The Peace Project was planned to deliver regional hydrogeological data through an integration of pre-existing data from shallow wells and 3-D seismic surveys with the results of an airborne geophysical survey. Airborne geophysics was considered an essential tool to provide more cost-effective and time-efficient coverage of a large area, than ground-based geophysical methods. The AEM system employed for the project was SkyTEM312FAST, a helicopter-borne TDEM system. The 8000 km2 area was covered in 43 days.

The objective of the AEM survey was to collect resistivity data from near surface to depths up to 300 m and combine this new information with prior data to 1) interpret potential Quaternary and bedrock aquifers within the area; 2) provide a map of the Quaternary–bedrock interface and thus Quaternary sediment thickness; and 3) generate a magnetic structure map of the basement. In general, it is expected that a joint interpretation of all geophysical data will help to determine optimal places for accessing and/or protecting the groundwater and finding non potable sources of water for energy sector use.

The AEM survey involved collecting over 21,000 line-km of data, covering an area of about 8000 km2.The airborne system used, SkyTEM312FAST, collected TDEM and magnetic data with an average speed of 118.8 km/h over the entire survey area. Preliminary data was delivered for quality assurance-quality control purposes every 48 to 72 hours to a third-party consulting firm. At the time of writing this paper, the final data and inversion results were still in the processing stage.

An important component of the airborne survey was communication and outreach with Treaty 8 First Nations and
communities within the survey area. Flights were planned and co-ordinated daily to avoid disturbance of First Nation cultural events, farmers and ranchers in the area. Through discussions with the Blueberry River, Doig River and Halfway River First Nations, the original survey area was expanded to include areas of interest over sections of their traditional lands. Additionally, an area around Fort St. John was flown in response to a request from the Peace River Regional District

Based on the raw data presented above, data-inversion was carried out using the laterally constrained inversion (LCI) method developed at Aarhus University, Denmark. The LCI technique is a relatively new inversion methodology whereby field data are filtered then modelled against a subsurface layer structure that is constrained laterally on a number of chosen model parameters (including layer conductivity and layer thickness).

The inversion results show very detailed structures in both the near-surface and deeper layers. Higher resistivities in the northwestern corner at all depths correlate with the presence of bedrock. High values of resistivity present in the shallower levels, indicate the presence of coarser material, such as sand, gravel and till, near the surface. The deeper levels are dominated by lower resistivities, which indicate the presence of more clay-rich material, till, water saturated sediments and/or bedrock shale and siltstone.

The report including data and results can be downloaded from Geoscience BC’s website here: http://www.geosciencebc.com/i/pdf/SummaryofActivities2015/SoA2015_Brown.pdf

Peace_Project

Report from SkyTEM survey on Gotland in Sweden

SkyTEM survey on Gotland

 

In 2013 the Swedish Geological Survey, SGU, contracted SkyTEM to survey the Swedish island of Gotland.

The surveys aimed primarily at studying the hydrogeological conditions of groundwater extraction in four areas on Gotland, which were assessed as being particularly interesting from a hydrogeological perspective.

The results show that the SkyTEM method is very well suited for surveying the geology on Gotland. The interpretation of the data acquired has resulted in a number of areas identified as important for future investigations  for groundwater extraction.

For each of the survey areas a map has been drawn up, showing the depth to the level with risk of salt water encroachment.

The full report has been published and can be downloaded from SGU’s website here.

SkyTEM516 over Caber Deposits

SkyTEM516 over Caber Deposits

The on-going development of SkyTEM MultiMoment® TEM systems has been driven by specific exploration objectives. First, to increase the power and depth of penetration. Second, to reduce the noise level and enhance detection of subtle contrast at depth. The result of a 5 year development program, SkyTEM516 has recently demonstrated its accomplishment of these objectives over the Caber Deposit in Québec, Canada. SkyTEM516, with a transmitter area of 536 m2 and 16 turns, is capable of delivering a dipole moment of more than 1,000,000 NIA. In addition, a unique receiver design has been engineered to reduce the noise level by a factor of 20.

The Caber North deposit is particularly suitable for testing a helicopter-borne EM system’s signal-to-noise as it is a challenging target and one that conventional ground EM systems have difficulty detecting. The deposit (1.3 Mt @ 4.0% Zn, 1.7% Cu) is buried under more than 300 meters of conductive overburden. SkyTEM516 and SkyTEM512 (launched in 2014) are both proven to successfully detect the Caber North deposit. Detection of this target is difficult because its response ranges from 2 to 10 fV/Am4 where 1 fV=10-15 V. Hence, detection of Caber North and similar targets requires a dipole moment in the range of 1,000,000 NIA and, above all, an exceedingly low noise level.

The SkyTEM516 has an un-normalized target responses range between 2-10 nV/m2. Therefore, in order to detect this target the noise level must be markedly lower than 0.5 nV/m2. Few airborne EM systems are capable of achieving this since systems with a high dipole moment typically have a corresponding high noise level due to limitations of the receiver system. As a result, many systems are incapable of detecting the Caber North Deposit due to an inferior signal-to-noise ratio.

All SkyTEM MultiMoment® systems are capable of mapping the near surface concurrently with depth. A range of systems is available to provide solutions for varying exploration objectives.

Download the brochure with test results here: SkyTEM516 over Caber Deposits.

 If you would like to see the entire test results, please send an email to CEO Flemming Effersø, , with your name, organization and email address. We will respond to you within 1 or 2 working days. You will be asked to sign a confidentiality agreement before you receive link and password to an FTP site.

SkyTEM312FAST

SkyTEM fast 312 SkyTEM, architects of MultiMoment® TEM technology, once again take airborne geophysics to the next level with the fastest helicopter data acquisition available. Engineered with a rigid aerodynamic carrier frame SkyTEM312FAST remains straight and level during high-speed flight benefiting data quality as well as survey efficiency and economy.

 

  • Data collection at speeds up to 150 kph
  • Late time gate of 15 ms and 510,000 NIA to maximize depth of penetration
  • Ideal for large regional surveys and data collection over level terrain
  • Low terrain clearance between 35 to 60 m and ability to drape fly
  • High logistics flexibility with traditional mob rates and short ferry distances
  • Delivery of high quality data within 24 to 48 hours of acquisition

Download one-page fact sheet here: SkyTEMFAST.