Avoid the Rock Meet the Needs

    One of the activities JEN provides, through support from Japanese Government and all of you, is construction of agricultural wells. The other day, we ran a soil survey for those wells in eastern Sri Lanka’s rocky Batticaloa region.

    Working with engineers from the Bureau of Irrigation and Water Supply, we begin by picking out a location suitable for excavation, then using a ground probing radar system called SYSCAL RIPLUS to investigate the condition of the soil.

    Next comes electrical resistivity* testing: we make a reference point, and draw lines out straight to either side using a tape measure.

 

    We then follow that line, driving in stakes every 50 cm on either side, and run an electrical current through the soil to test its quality.

    This process is repeated at 1m, 1.5 m, 2m and 3m from the reference point.

    Using the figures from the survey, the engineers draw a line graph. Each reading allows them to tell if there are rocks or water veins at that location, and analyzing them provides soil, water and other geological information.

    *Electric resistivity: a substance's resistance to electricity. The more water there is in underground sediment, the easier it is for an electrical current to pass through.