The embankment dam at Lövön was built between 1972 and 1973 and has a total length of 1500m, and a height of 25m. Leakage water cannot be collected and measured by conventional leakage systems, due to a high downstream water level. Two optical fibre loops were installed in 1998 to measure the temperature upstream, above and downstream from the core. The optical fibres are located on eight levels at different distances from the dam centre line.
The first measurements were carried out from mid November 1998 to mid February 1999. In 2004 a second measurement was made using a newer DTS, with an accuracy ten times better than the system used in 1998. Calculated temperature trends (in the order of 0.01°C/day) agree well with those obtained from the very accurate vibrating wire temperature sensors. A couple of more measurements have been made since then, where the latest was using Silixa XT-DTS with a sampling resolution of 0.25 m.
Evaluation using DamTemp, and based on short-time DTS measurements and continuous temperature measurements in temperature sensors indicated maximum seepage flow rates about 20-30ml/(s,m). A concentrated seepage flow about 0.05l/s was detected at chainage 0/028. A wider seepage area was also detected between chainage 0/045 and 0/060 with total flow of about 0.5l/s.