Abstract

In order to get an apparent resistivity map of quite a large area which required a considerable amount of time (months) and because of the occasional availability of equipment and bad weather conditions causing postponing of certain campaigns, the area was divided into adjacent sub-areas which were mapped in a considerably separated measuring days. Because of the rainfall changes from one campaign to another, the final apparent resistivity map obtained by superposing all the different measuring day’s maps is obviously misleading. In the first stage, this disturbing effect was highlighted by carrying out profiles in the beginning of each measuring day on a specific line of the grid (the first line) just before mapping the corresponding sub-area. This was achieved first for the shallowest part of the grid, and then for the deeper parts. In the second stage, a removal of this effect was performed by applying a method of correction which consisted of bringing a specific measuring day apparent resistivity values close to reference day values. Once a given measuring day apparent resistivity was corrected, the remaining random errors were estimated.

Keywords:  Moisture, temporal resistivity, rainfall, day reference, line reference.