The Säterberget Gully at Brattforsheden, Värmland, Sweden

Abstract

During the final phase of the snow-melting in the spring of 1977, mass movements of water-soaked, silty-sandy deposits were recorded in central Värmland. The precipitation was approximately twice the seasonal mean value. In a narrow valley beside Säterberget Hill, as a result of these mass movements, a gully was formed in a sequence of more than 15 m of silt and fine sand. At the bottom of the gully, the silt was clayey. The gully has a depth of 3–20 m, a width of 20–40 m and a length of more than 100 m. In less than three days, about 20 000 m³ of silt and fine sand were transported almost 300 m through an old gully to an adjacent river. Human modification of the landscape was a contributory factor in the gully formation. A defective drain-pipe under a three-road junction caused a rivulet to flood and take a new course. The drainage area of the rivulet had been enlarged by ditches constructed along the hillside road. Furthermore, the run-off down the slope had been increased due to the clear-cutting of timber.