The Fharmor project

Most Alpine river reaches are subjected to hydro-morphological alterations related to water abstractions, dam operations, channelization, ultimately leading to habitat degradation, one of the most relevant causes of loss of freshwater biodiversity. Quantification of habitat availability in rivers is strategic for sustainable river management especially when multiple river uses are present. Among the existing approaches to assess habitat quantity and quality in rivers, the analysis at the “mesohabitat scale” is proving as one of the most effective, with meso-habitats physically reflecting the interplay between hydraulics and river morphology at a suitable spatial scale for ecological analyses. By coupling ground measurements of the spatial distribution of the mesohabitats with multivariate statistical biological models, it is possible to convert the discharge time series into habitat time series, which metrics are a powerful tool to support decision making in relation to water withdrawals, flow regime and discharge manipulation because they allow to quantify the habitat response to different management options.

However, several limitations still reduce a broad applicability of this approach. Firstly, mesohabitat mapping is almost unfeasible in large streams, meaning non-wadable even under low flow conditions. Secondly, mesohabitat mapping needs to be performed under the broadest possible range of water discharge values, in order to obtain a reliable habitat rating curve for a river reach: this can be highly time-consuming and limits the number of reaches where the methodology can be applied. Thirdly, most of the available studies for river habitat dynamics do not account for the role of event-scale (disturbance) and medium term (trajectory) river morpho-dynamics which reset the habitat template and thus are a crucial source of habitat variability.
The FHARMOR project aims to address the above limitations by investigating the potential of several complementary approaches to quantify the spatial distribution of mesohabitat characteristics. Namely, FHARMOR will focus on hydro-morpho-dynamic modeling and remote sensing techniques, including bathymetric lidar, and hyperspectral imagery. The ultimate goal of FHARMOR is to develop an integrated methodological approach to the quantitative habitat assessment and prediction method that can be applied over long river reaches and across a broad range of river sizes for management purposes.

The FHARMOR project team will predict the spatial and temporal patterns of meso-scale habitat for selected fish species of particular management and conservation interest, like grayling (Thymallus thymallus) and marble trout (Salmo trutta marmoratus). The project team is interdisciplinary and is composed of hydraulic engineers and experts in remote sensing of rivers (University of Innsbruck), hydrologists and geomorphologists (Free University of Bozen-Bolzano), experts in eco-hydraulics and modellers of river hydro- and morphodynamics (University of Trento) together with experts in fish habitat studies (external collaboration).

The methodology will be developed referring to three different river reaches located in South Tyrol, having contrasting characteristics in terms of channel size, hydro-morphology and level of anthropic pressure: Mareit River upstream of Sterzing, Ahr River upstream of Bruneck and Eisack river nearby Bozen. In-stream, remote sensing and modeling approaches will be jointly tested at the field site that is wadable at low flows (Mareit River). Remote sensing and hydro-morphodynamic modeling will then be applied to the larger Ahr and Eisack study reaches. Moreover, a multivariate biological model for the grayling will be developed, because of its strategic conservation interest especially in the Ahr and Eisack rivers. Finally, hydro-morphodynamic modeling will be used to predict likely scenarios of future habitat changes in response to strategies of river restoration of particular interest for South Tyrol (ex. river widening, gravel augmentation).



Comments are closed