Resistivity and SP Surveying and Monitoring at the Sädva Embankment Dam, Sweden

Initial monitoring trials of resistivity and self potentials (SP) in order to study the seepage through dams, was carried out in the Sadva embankment dam, Sweden. A portable surveying equipment was connected to electrodes that were installed in the dam in 1999. The SP study (including a downstream and offshore survey) showed quite smooth variations. Most anomalies could be related to known features of the dam construction. The result gives basic information of the geo-electric situation, essential for future evaluation. The resistivity study comprised measurements at two different times (October 1999 and June 2000). The data sets are of good quality thanks to good electrode contact and stable conditions. Most parts of the resulting sections show low seasonal variation whereas there are some areas with larger variation, notably on the dyke. An automatic monitoring system will be installed in 2001 within a research project. Daily data will then improve the possibilities for interpretation and seepage evaluation.