Context

The RECONECT project, funded by the European Union’s Horizon 2020 research and innovation programme, aims to demonstrate the effectiveness of Nature-based Solutions agains hydro-meteorogical risks and to upscales them through an holistic ecosystem-based framework and the network of demonstrators.

In the Inn River catchment, located near Innsbruck, Austria, flooding and confluence situations lead to critical situations. Biological nature based solutions are implemented since early 1950 in many torrents of the catchment in order to reduce the impact of floods. Such measures involve the change of land use, creating grass land or support reforestation and expansion of forested parts of a catchment.

Total length of the torrent main channel is 8 km, with the highest peak at an elevation of 1920 m. The overall catchment comprises of the torrential catchments Geroldsbach (12 km2) and Marbach (1.2 km2) with two urban catchment parts (Götzens and Neu-Götzens) located in the downstream part.

The initiative

The demonstration concept applied in the framework of the RECONECT project is a mix of monitoring and modelling based approach. In the lead catchment, the rural/torrential catchment as well as the urban catchment are assessed with regard to runoff processes linked to various land use options. The development and effects of measures over time are addressed on a modelling basis using the monitoring data. Historic data sets and the thereby covered changes in land use given in the torrential and urban catchments are quantified an evaluated. Implementing hydrological models covering the total catchment allows to quantify the benefits for different event magnitudes and spatial distributions of storm events.

Beyond realizing historic and current situation exclusively, dynamic land use change over time and potential future scenarios are set up. Novell aspect here is, the quantification of benefits and limitations gain able by urban vs. torrential NBS together with technical measures. For both, impacts varying over time and for different catchment configurations are elaborated.

Results, limits and enable factors

Besides the reduction of flood flows, the recreation of mountain catchments provides local areas for nature based recreation zone, tourism activities and enhances the biodiversity. For generalizing and upscaling of the findings, especially with regard to (a) land use in torrents (b) land use at the urban scale, models are realized as well for different other torrential/urban catchments.