See brilliant video at The Wall Street Journal.
SkyTEM takes the stage at the 6 min 15 sec mark.
See brilliant video at The Wall Street Journal.
SkyTEM takes the stage at the 6 min 15 sec mark.
The ability to reveal the availability and movement of groundwater can be a huge asset for countries and regions with the need to responsibly and sustainably manage their aquifers.
The SkyTEM method, specifically developed to map buried aquifers, is widely accepted globally as the principal technique for mapping water resources. SkyTEM is an innovative and technologically advanced airborne geophysical system capable of mapping the top 500 metres of the Earth in fine detail and in 3 dimensions. SkyTEM was conceived and engineered in Denmark, a country with a reputation for environmental care and R&D. SkyTEM helps geological organizations and government water agencies on seven continents unearth a wealth of information about their aquifers and aids in their understanding of how geology and mankind can affect, and be affected by, groundwater resources. The SkyTEM method has mapped water resources on a Galapagos Island, important agricultural areas in the USA, Australia, Africa and India, islands in the Caribbean and Indian Ocean and even Antarctica. Recognized for its ability to quickly and accurately map geology in fine detail, the SkyTEM method is also employed globally for mineral and oil & gas exploration as well as environmental and engineering investigations.
This white paper provides results from recent global water exploration projects – from finding new fresh water sources to identifying groundwater recharge areas, saline water encroachment and more.
Water is essential for life on earth. Two thirds of Earth’s surface is covered by water and oceans hold about 97% of all our water. In the remaining 3% of fresh, or non-saline water, groundwater provides us with 30% of all our drinking water while 68% is trapped in a frozen state. Less than 2% is available as surface water. This limited supply of available surface and groundwater is the main source of drinking water for the planet’s seven billion plus people. In recent decades as demand for water increases we witness falling water levels in almost all of the world’s wells, and many are beginning to run dry.
According to a recent NASA study one third of the Earth’s largest groundwater basins are being over-exploited. Twenty-one of the world’s 37 largest aquifers, in locations from India and China to the United States and France have removed water quicker than it can be replaced by rain and snow and their sustainability is at a critical point. (see http://go.nasa.gov/1G3fLIV). Depletion of water resources is an immediate and growing concern and is creating overwhelming challenges for the next generations.
Click here to download the entire white paper: Mapping Groundwater with SkyTEM
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.
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.
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
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.
A scientific article written by J. A. Mikucki, E. Auken, S. Tulaczyk, R. A. Virginia, C. Schamper, K. I. Sørensen, P. T. Doran, H. Dugan and & N. Foley published in Nature Communications describes how the SkyTEM method was used to map groundwater in Antarctica. Read the abstract below and the full article here:
The occurrence of groundwater in Antarctica, particularly in the ice-free regions and along the coastal margins is poorly understood. Here we use an airborne transient electromagnetic (AEM) sensor to produce extensive imagery of resistivity beneath Taylor Valley. Regional-scale zones of low subsurface resistivity were detected that are inconsistent with the high resistivity of glacier ice or dry permafrost in this region. We interpret these results as an indication that liquid, with sufficiently high solute content, exists at temperatures well below freezing and considered within the range suitable for microbial life. These inferred brines are widespread within permafrost and extend below glaciers and lakes. One system emanates from below Taylor Glacier into Lake Bonney and a second system connects the ocean with the eastern 18km of the valley. A connection between these two basins was not detected to the depth limitation of the AEM survey (~350m).
The SkyTEM101 system was developed for the NiCA project (Nitrate Reduction in a Geologically Heterogeneous Catchment – www.nitrat.dk) and was tested in the Norsminde Fjord catchment in Denmark as part of the project. The purpose of the geophysical mapping was to map the near surface aquifers by producing a detailed description of the geology in the upper 30 metres. This geophysical mapping then forms the basis of detailed geological and hydrological models for determining the transport and reduction of nitrate in the catchment.
This case study compares the airborne mapping with drillings and the project was conducted by SkyTEM Surveys ApS, Aarhus Geophysics ApS and the HydroGeophysics Group, Aarhus University.
Download the case study SkyTEM101_NiCA.
A report has been published by the Hydrogeophysics Group at Aarhus University on the first survey made with the new SkyTEM101 whose very low moment and short turn-off allow the use of very early gates down to a few µs. This survey was made as part of the NiCA project (www.nitrat.dk) in which the purpose is to model the reduction of the nitrates in the near-surface aquifers (top 30 m), in order to propose a better optimized regulation of the use of fertilizers by identifying the more risky areas.
Download the full report (331 MB) here.
Rethink Water & Danish Water Forum have published a white paper on the provision of fresh water and the ambitious groundwater mapping programme in Denmark, which has laid the foundation for the groundwater expertise of Danish companies. Today this expertise, which includes surveying technologies, software tools for integrated water resource modelling and decision-making systems.
In most parts of the world groundwater mapping is based only on one data source: drilling information. However, low borehole density means that this strategy often leaves many uncertainties in the models. In Denmark, and a few other countries, geophysical measurements are used in conjunction with drilling to map aquifers. Intensive, large-scaleuse of geophysical methods, particularly airborne electromagnetic surveys in an integrated workflow together with drilling, makes mapping results more accurate and reliable.
Download and read the entire White Paper – Ground Water Mapping.
From 1956 until 1973, untreated wastewater from a chemical plant was dumped into 6 pits in a plantation in the south-western part of Jutland, Denmark 0.5-1.0 km from the coastline. Today, it is one of the worst pollution scenarios in Denmark with high concentrations of e.g. chlorinated organic solvents.
As an alternative to a costly offshore drilling campaign, a small SkyTEM TDEM survey starting 1.0 km inland and ending 1.0 km offshore was flown in 2006.