ABSTRACT
The global hydrological cycle became more intense during the recent past which can be observed in media attention too. That is the reason why one has to worry about a greater extent and/or more intensive geomorphological damaging events like debris flows and exceptional floods. To get information about the probability and the consequences of these increasing events, it is necessary to analyze the availability of sediments in the catchment area and the transport of the sediments along torrents.
The project Clim Catch, which started in April 2012, investigates the torrential sediment transport processes in a non-glaciated Alpine valley in Austria and the related natural hazards under the viewpoint of the on-going climate change. Due to an extreme precipitation event in 2011 debris flow-similar discharges occurred in this catchment and since then the sediment sources are highly erodible there. The aims of the project are to derive a quantitative sediment budget model, including geomorphologic process domains, determining sediment transport in the river system and the measurement of bed load output, besides others.
To quantify river sediment dynamics several different methodologies are applied within the project. Discharge and sediment transport measurement as well as hydrological stations are installed in the project area. Aggradation and erosion are analysed by means of laser scanner technology in the sediment storage basin which is located at the outlet of the catchment. The observation and measurement of the sediment transport is done by the application of radio telemetry stones and color tracer stones. Line pebble counting, automated grain size determination using photographs and sieving on-site are undertaken to get qualitative sediment information. The correlation of the sediment transport with discharge data and the comparison of sediment transport measurements with available formulae and 1 -dimensional-sediment transport models are performed.
In order to connect sediment transport processes to climate change, the correlation between heavy precipitation events and debris flow will be analyzed. Future extreme precipitation events will be modeled by the improvement of downscaling approaches, especially for sub-daily scale. Furthermore, uncertainties in local extreme precipitation will be estimated quantitatively. The introduction of the development of scenarios of future catchment dynamics and of the assessment of mitigation measures will complement this paper.
