Watershed characterization using seasonal time-lapse DC resistivity data

Changes in water saturation can cause significant changes in the electrical conductivity of near surface materials. Thus mapping changes in the conductivity distribution during wet and dry periods provides an indirect way to quantify changes in the saturation of the near-surface medium. This, in turn, leads to better understanding of the water mass balance in a watershed characterization problem. The conductivity imaging can also provide other information such as fracture orientations within the near-surface medium. At Dry Creek watershed; situated at 1830m elevation near Boise, Idaho; we study seasonal changes in saturation using the time-lapse DC resistivity method. Four DC resistivity data sets were acquired between October 2005 and July 2006 to monitor the changes in conductivity. The results indicate that DC resistivity is a cost-effective tool to characterize a watershed and aids in the interpretation of other data collected in the watershed.