Day 1: Defining Our Scientific Objectives

This week, we will be looking for underground rocks which contain groundwater that could be used as a source of fresh water for the people of the Roseau Valley in Saint Lucia.  In order to detect the presence of water, we will conduct a series of surface conductivity measurements that will reveal the locations of any electrically-conductive, and potentially water-containing, rock layers at depth.  

Placing a stake in the ground for a test measurement of electrical conductivity.

For each measurement, we will set up two distant stakes in the ground as electrodes and apply a large voltage to induce a current between them.  In between these two electrodes, we will set up two more stakes with variable position and spacing, and we will measure the voltage drop between the two inner electrodes. By performing an inversion of the data, we can use the measured resistivity or conductivity values at the surface to give us information about the resistivity, and thus the water content, of the deeper layers of rock. 

Based on what we find, we will probably conduct a number of one-dimensional soundings and two-dimensional horizontal and vertical conductivity profiles in the Roseau valley.  

Stay tuned to find out more!