OurDam08_evaporation

To assess the seepage gain of the dam, and the leakage of the dam wall, we measured evaporation, rainfall, and the water level of the dam daily from July 2005 to July 2006. The Evaporometer consisted of an evaporation pan of approximately 150 mm diameter, which could be completely drained. Every day we filled a certain amount of water into the evaporation pan, and 24 hours later we measured the volume of the remaining water. The difference, i.e. the "missing" water, had evaporated. To make sure the evaporation pan was exposed to a temperature similar to the temperature of the dam water, it was placed inside a crate that was filled with dam water, which was continuously circulated with an aquarium pump.

These measurements suggested that the seepage gain as well as the leakage of the dam is negligible. The dropping of the dam water level throughout the summer is explained by the evaporation.