Objective of the flight:
To investigate potential sites of groundwater upwelling along the many dolerite dykes in the area. Such upwelling can often be best seen from the air, due to subtle soil colour and vegetation changes. It would be important to identify such sites to show the risk of shallow groundwater pollution from the proposed hydraulic fracturing for shale gas in the Karoo. Further geological field research could be better targeted. We also hope to get impressive images for SAFCEI’s education work with local communities regarding the risks of shale gas developments.
Pilot: Sholto Kroon
Aircraft: Cessna 210
Beneficiary: Dr Stefan Cramer, Southern African Faith Communities’ Environment Institute (SAFCEI)
Report from the beneficiary, Dr Stefan Cramer:
“This Bateleurs flight helped to investigate sites originally identified by geological field work of Dr Stefan Cramer. We are pursuing a theory originally formulated by the late Prof. Gerrit von Tonder from the University of the Free State that dolerite dykes in the Karoo are often sites of groundwater welling up from deep and mineralized aquifers. It has long been known that dolerite intrusions are often accompanied by excellent fracture aquifers. Many Karoo farms are actually sited just below dolerite dykes, as their supplying springs would surface just above these intrusions. The flight images show excellent examples of this relationship. It is less clear, if and how much deeper groundwater percolates through these intrusion-related fracture zones. This question is of strategic relevance for the future of the Karoo. If hydraulic fracturing for shale gas mining would ever go ahead, toxic fracking fluids injected into deep levels could rise up with upwelling groundwater and pollute drinking water supplies in the Karoo. Future research already underway will try to test this hypothesis. The ongoing field work by Dr Cramer has already shown that there are numerous sites where such upwelling may be seen, where dolerite-related spring waters have an abnormal mineral composition. Such sites can be easily identified because of their lime and salt efflorescence from aerial photography. In fact LANDSAT and other Google Earth images show this relationship in sometimes striking pictures, depending on the ground conditions at the time of the satellite pass. The main assumption for this flight was the fact that airborne images should get in much closer with much higher resolution. Future field work and spring sampling should be guided by a quick overview over promising sites.
Yet, this flight was originally planned for September 2014 at the height of the dry season, when even subtle differences in soil humidity can be easily seen from above. Now the flight took place 6 months later than planned at the end of the rainy season with exceptional rains just two weeks before the flight. The abundant vegetation – while excellent news for the Karoo farming communities – largely masked the minute differences of soil moisture due to upwelling of groundwater. The rains also had washed away – with a few notable exceptions – traces of mineral efflorescence (salt, lime, etc.) which are due to the evaporation of mineralised spring water welling up from deeper layers. The flight would thus have to be repeated in October 2015 to obtain comparative and probably more indicative results.
The entire flight was an excellent experience. Without the experienced flight planning by our pilot Sholto Kroon long before we took off it would not have been possible to cover more than 20 sites in about 2 hours flying time. It would be very interesting to redo this flight in October 2015 under the same conditions and compare the images. In the meantime we will continue our ground work to monitor the spring sites more closely with appropriate water analysis. We sincerely hope that BATELEURS can follow this up with another flight in October 2015. Of course we hope that Sholto Kroon will be again our experienced pilot. Flying such complicated missions is not an easy task and it takes someone as experienced in this part of the world as him to get us at the right time in the right angle to the right place.
Many thanks indeed.”
Report from the pilot, Sholto Kroon:
“The mission was flown on Monday afternoon, the 20th of April 2015. Weather was clear with slight Southerly wind.
The flight entailed the identification and positioning for aerial photography through a closed window of about 30 predetermined points/sights mapped by Dr Stefan Cramer from an average altitude of 1000’ agl. The planning of the approach and positioning of the aircraft for “closed window” photography” was essential to minimize any oblique shots, through the window, as this would be detrimental to the quality of the photographs.
I need to thank Stefan for his thorough planning prior to the flight making my planning very simple. As mentioned in Stefan’s report the very good autumn rains made some of the sights less obvious to identify from the air, nevertheless, I think he was happy with the mission.”