Author(s): G. Markart; B. Kohl; G. Poscher; W. Wanker; I. Schnetzer
Linked Author(s):
Keywords: Surface runoff; Runoff coefficient; Infiltration; Spray irrigation installation; Heavy rainfall
Abstract: In the summer of 1997 the Wartschenbach settlement, forming part of the community of Nussdorf-Debant in Eastern Tyrol, was within three weeks twice severely damaged by debris flows. Within a very short period of time (1. 5 months) information concerning runoff and infiltration characteristics of the most important soil vegetation units in the upper catchment area of the Wartschenbach river had to be provided to the Austrian Ministry of Agriculture by the Institute for Avalanche and Torrent Research of the FBVA. Six differently managed research plots (meadows, skiing areas, pastures) were irrigated by the use of a spray irrigation installation with a rainfall intensity of approx. 100 mm/h. The best runoff characteristics in combination with the longest runoff delay were obtained with a well prepared meadow. The worst runoff characteristics were documented on intensively stressed plots of land (graded or intensively grazed areas). At a graded meadow, for example, the runoff coefficient was 0. 9. Soil physics investigations yielded a significant loss of pore volume and a decrease in saturated hydraulic conductivity at a soil depth of 10 cm on the stressed plots of land. Mapping of lithology and structural geology, vegetation, intensity of cultivation, and selective surveys of soil physical properties, as well as results from other investigations cited in literature were used to extrapolate the runoff coefficients derived from these research plots to the entire upper catchment area (1. 5 km2). Founded on these results, a map of runoff coefficients was produced, which served as a basis to calculate the potential runoff supply to the Wartschenbach in case of heavy rainfalls.
Year: 1999