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Oom-Johan-divines-water-on-JackyBird-Farms-while-Robin-watches.jpg Water Divining on JackyBird Farms
By: TB   (2013-10-06)

Judge for yourself: science or something else?

Johan Verreyne, from Montagu, who maintains our borehole pumps on JackyBird Farms, is also able to 'dowse' (or 'divine' underground water flows). Usually this skill is applied to find new potential water sources. However, in our case a borehole was already in place but unused and, before spending money to renovate the pump, I wanted to estimate the borehole's flow potential; i.e. its capacity to provide water on a continuous basis without becoming exhausted. The hole does contain water so we know for certain that it intersects underground faults (cracks) through which water flows. Before any pumping started, the water surface in the shaft was measured to be 3m below ground level and the shaft itself was measured to be 109m deep - a fair column of water.



How did the water dowsing take place?


  • before any pumping began, Johan moved around the hole about 5m-10m from it with his divining rod (a simple length of once-twisted cane) held horizontally. At certain places (when he crossed a fault?) the rod twitched (see video #1 below). By counting the number of twitches, he estimated the volume of water flowing through each fault. These values were added up as the potential total flow capacity of the borehole; in this specific instance apparently around 20,000 litres per hour.
  • we then started the pump. It pulls about 7,000 litres per hour. Johan immediately went back to the same spots and freshly measured the water flows. These values were also noted and added up as being the residual water still flowing through the faults despite the pumping. This totalled around 12,000 litres per hour, or 60% of the apparent maximum capacity. Good! Experts recommend always leaving about 40% unused so that the hole can quickly replenish itself. The pump was left to run continuously, filling one of the dams. The water tastes good and a sample has been sent for quality testing.
  • after five days the water was still flowing strongly and Johan returned to dowse at the same spots again. This time he estimated that the total residual water flow had apparently dropped to around 50% of capacity. Indeed, of the five faults measured, three had reduced, one had no residual flow at all (emptied?) and one was greater than before (perhaps it had connected through to and diverted the water away from the now empty fault next to it).
  • Johan then again moved around the borehole but this time at each fault he held the rod vertically and used its twitching to tell him what the direction of the flow was (video #2 below: as you can see the rod seems to be very sensitive over small sideways distances). What particularly interested me was that one of the faults appears to run directly in line with another powerful borehole some 300m away upsteam. Perhaps they both feed off the same fault. In which case it will be intriguing to see if our new hole exhausts more quickly when we run the other pump at the same time.

 

So at this stage the fresh borehole appears to be fully sustainable, pumping good quality water at a rate of 7000 litres per hour, apparently with about half or more of its maximum capacity still in reserve. In another week or so we will check again and also once more measure the depth of the water below the surface to see if the local water table has been lowered at all by our pumping or if the residual inflows are sufficient to keep it filled. We will also test to see if it is affected when the other distant pump runs simultaneously. Finally; based on this first experience I intend to later have all our operational boreholes 'dowsed' to estimate the aggregate maximum water capacity available through the eight boreholes on JackyBird Farms. As a control, we have the capacities of each borehole originally estimated by our irrigation systems supplier, Spilhaus.


Tom Brown.



 






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