The importance of soil protection and conservation in mountainous areas for hydrological purposes Bernhard Kohl, Gerhard Markart Austrian Institute for Avalanche and Torrent Research Federal Office and Research Centre for Forests (BFW), Rennweg 1 – Hofburg, A6020 Innsbruck, Austria.
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[email protected] 1. Introduction A transportable spray irrigation installation for large plots (50 to 400 m²) was constructed at the Austrian Institute for Avalanche and Torrent Research (AIATR) with the aim to characterise and define the different runoff producing areas in torrent catchments. In the last fifteen years 135 different soil/vegetation units were irrigated and 234 rain simulation experiments were carried out. Additionally soil water status was monitored by TDR-probes installed in several profiles at the irrigation plots in different depth for observation of infiltration and wetting behaviour of the soils. Detailed characterization of vegetation (list of the species, description of abundance/ dominance and on some plots analysis of frequency and plant biomass) as well as analysis of the most important soil physical properties completed the research programmes. The results of these and other numerous rain simulation experiments in the eastern Alps indicate that runoff in torrent catchments besides geological and soil physical characteristics is depending to a high extent on plant cover as well as on way and intensity of cultivation (Markart et al., 2004). Looking at the torrent catchment as the level of interest it can be shown, that long-term integrated ameliorative measures (e.g. abandonment of grazing, afforestations, optimization of remaining grazed areas) are very effective in reducing runoff and erosion potential. Investigations on surface runoff development by use of the portable spraying irrigation installation for large plots in Meran 2000 (South Tyrol – Italy) showed an increase in runoff and erosion potential on grassy stands in the following order: Vegetation area covered without grazing or other mechanical impact < vegetation covered area and addition impact (cultivation, grazing…)
