Spring Run off Forecasts from Snow Assessments in the Malmagen Area at 62° N in Sweden

ABSTRACT

The spring run-off was forecast by evaluating the snow pack, the precipitation, the evaporation and the change in ground water and soil moisture during the melt season. The snow pack is the most important run-off factor. A snow map has been made up from a number of measuring points to serve as “ground truth” (key) in order to simplify the methods of assessing the snow pack, i.e. measuring the snow depth and determining the snow density along some suitable profiles. The height above sea level has to be determined for every observation point. The results obtained deviated at the most 10% from results gained by the snow map. The run-off forecasts proved between 2% too low and 20% too high for three investigation areas during two subsequent years. Aerial photographs of the investigation area have suggested a connection between the percentage of snow covered ground and the remaining run-off during two years.