Final Report Summary - HOLRIVERMED (Environmental River Management: An Innovative Holistic Approach for Mediterranean Streams)
HolRiverMed consisted of a structured two-years research program hosted by the Universidad Politecnica de Valencia (Spain) and it was mainly focused on models and methods for a sustainable water resources management in the Mediterranean area. The project was funded by the European Union through its Seventh Framework Programme. In particular, HolRiverMed was part of the 2010 Marie Curie Intra-European Fellowships for the mobility of European researchers.
In the Mediterranean area water abstractions strongly affect water-related organisms, increasing the duration and magnitude of droughts and impairing the capacity of streams to support the ecosystem. This alteration of the natural flow regime act on biota through an hydro-morphologic template. Consequently, the development of models and methods able to relate stream flow alterations and the ecological responses of aquatic and riparian species is a fundamental issue for water resources management, including the maintenance of water quality and quantity for wildlife conservation.
In response to the present scientific criticisms and to the lack of available information, the HolRiverMed project aimed to devise improvements for the environmental management of Mediterranean streams (i) for a comprehensive analysis of various taxonomic and functional groups composing the riverine ecosystem, (ii) to represent rivers at large spatial and temporal scales and (iii) to provide knowledge and ecological understanding of temporary and intermittent watercourses. The project was based on the meso-scale (or meso-habitat) resolution to reveal spatio-ecological patterns and describe the whole river system properties. Mesohabitats or hydro-morphological units (HMUs, such as pools, riffles, rapids, etc.) is a definable area which reflects the interplay between hydraulics and riverbed topography and can be inferred by visual observation of surface flow character and verified by water depth, flow velocity and substratum types.
To develop models and methods for the management and conservation of Mediterranean riverine ecosystems, the analysis was carried out in a structured multidisciplinary approach among hydraulics, hydrology, ecology and biology, as it is typical in the field of eco-hydraulics. The project involved universities and research institutes across the Mediterranean area and included several case studies in Spain (Jucar and Turia river basins), Italy (Po, Adige, Arno, Magra-Vara, Tordino and Saline river basins) and Greece (Nestos river basin). Project activities were carried out thanks to the ongoing collaborations with several researchers and the support of local authorities. Flexible tools were developed for the efficient implementation of the obtained methodologies and the applications within different river basins contributed to the development of a sustainable water resources management in the Mediterranean area.
Research analyses considered different taxonomic and functional groups (fish, macroinvertebrates, mammals and riparian vegetation) to investigate biotic interactions and to describe the biological response to hydro-morphological alterations. Based on the project results, mesohabitat suitability models were well suited as a planning tool in different environmental contexts, including both perennial and intermittent watercourses. Specifically, they were used to select ecologically effective restoration measures for threatened species and for establishing ecological flow criteria at hydropower plants or water withdrawals. The different applications of this meso-scale approach demonstrated interesting potentials to model habitat for a large range of taxa. Indeed, mesohabitats can be considered an appropriate scale resolution to capture the way in which water-related organisms interact with the spatial arrangement of habitat characteristics, also considering seasonal habitat changes and biotic interaction among species.
The Random Forests (RF) predictions, carried out in the framework of the project, exhibited considerable promise in developing predictive distribution models to support the conservation of different water-related organisms. The developed modelling approach, which uses the mesohabitat scale to include biotic interactions, can be considered more ecologically realistic to understand and describe the interplay of the different environmental variables. Moreover, RF can be suitable for both classification and regression analyses, and it showed interesting results to understand the main drivers of crayfish distribution, fish species richness and the inter-specific interactions between otter foraging behavior and non-native fish species. Lastly, RF also performed well when applied to riparian vegetation. Grouping riparian vegetation species into guilds gave even better results compared to single species modeling.
Habitat time series analysis and UCUT curves, combined with mesohabitat simulation models, were used to define an envelope of naturally occurring habitat events that are harmless to the fauna. These highly informative diagrams represent a three dimensional description of habitat distribution in the continuous duration/frequency space. Hence, environmental flows should fall within this envelope. The method also captured stress conditions that were created by persistent limitation of habitat availability and those created by catastrophically low habitat quantity (e.g. in periods characterized by zero flow conditions in intermittent streams). Furthermore, the application of habitat time series in the context of climate change (Rabbies stream, Italy) and to rivers affected by hydropeaking (Noce River, Italy) allowed the analysis of future habitat conditions and the comparison of hypothetical release scenarios related to possible reduction in hydropeaking intensity.
Till now, mesohabitat suitability models have been built to identify the habitat characteristics mostly used by target fish in perennial watercourses. However, a few studies have been carried out for other aquatic organisms and no applications are currently available neither for crayfish, nor for intermittent streams. In the crayfish study, the mesohabitat scale adapted well to describe habitat use by A. pallipes complex, and mesohabitat predictive models showed interesting potentials for future applications to intermittent streams. Moreover, model extrapolation have been evaluated in Central Italy (Tordino and Saline river basins) and results demonstrated the flexibility of the obtained predictive tools. The proposed methodology also quantifies habitat for aquatic organisms over a range of flows and under zero flow conditions. This constitutes an interesting result of the study and the proposed methodology seems to be adequate to assess e-flows and to design habitat restoration actions in intermittent streams.
We used the proposed meso-scale approach as a benchmark for present and future research studies. As a general rule of thumb, for meso-scale model extrapolation purposes, we can recommend to build biological databases using data from different streams with different morphologies and gradients. Data collected from multiple rivers, distributed at a regional- or at a catchment-scale, can provide a wider range of habitat conditions than those occurring in one single river, and can lead to a more flexible habitat simulation model.
In the Mediterranean area water abstractions strongly affect water-related organisms, increasing the duration and magnitude of droughts and impairing the capacity of streams to support the ecosystem. This alteration of the natural flow regime act on biota through an hydro-morphologic template. Consequently, the development of models and methods able to relate stream flow alterations and the ecological responses of aquatic and riparian species is a fundamental issue for water resources management, including the maintenance of water quality and quantity for wildlife conservation.
In response to the present scientific criticisms and to the lack of available information, the HolRiverMed project aimed to devise improvements for the environmental management of Mediterranean streams (i) for a comprehensive analysis of various taxonomic and functional groups composing the riverine ecosystem, (ii) to represent rivers at large spatial and temporal scales and (iii) to provide knowledge and ecological understanding of temporary and intermittent watercourses. The project was based on the meso-scale (or meso-habitat) resolution to reveal spatio-ecological patterns and describe the whole river system properties. Mesohabitats or hydro-morphological units (HMUs, such as pools, riffles, rapids, etc.) is a definable area which reflects the interplay between hydraulics and riverbed topography and can be inferred by visual observation of surface flow character and verified by water depth, flow velocity and substratum types.
To develop models and methods for the management and conservation of Mediterranean riverine ecosystems, the analysis was carried out in a structured multidisciplinary approach among hydraulics, hydrology, ecology and biology, as it is typical in the field of eco-hydraulics. The project involved universities and research institutes across the Mediterranean area and included several case studies in Spain (Jucar and Turia river basins), Italy (Po, Adige, Arno, Magra-Vara, Tordino and Saline river basins) and Greece (Nestos river basin). Project activities were carried out thanks to the ongoing collaborations with several researchers and the support of local authorities. Flexible tools were developed for the efficient implementation of the obtained methodologies and the applications within different river basins contributed to the development of a sustainable water resources management in the Mediterranean area.
Research analyses considered different taxonomic and functional groups (fish, macroinvertebrates, mammals and riparian vegetation) to investigate biotic interactions and to describe the biological response to hydro-morphological alterations. Based on the project results, mesohabitat suitability models were well suited as a planning tool in different environmental contexts, including both perennial and intermittent watercourses. Specifically, they were used to select ecologically effective restoration measures for threatened species and for establishing ecological flow criteria at hydropower plants or water withdrawals. The different applications of this meso-scale approach demonstrated interesting potentials to model habitat for a large range of taxa. Indeed, mesohabitats can be considered an appropriate scale resolution to capture the way in which water-related organisms interact with the spatial arrangement of habitat characteristics, also considering seasonal habitat changes and biotic interaction among species.
The Random Forests (RF) predictions, carried out in the framework of the project, exhibited considerable promise in developing predictive distribution models to support the conservation of different water-related organisms. The developed modelling approach, which uses the mesohabitat scale to include biotic interactions, can be considered more ecologically realistic to understand and describe the interplay of the different environmental variables. Moreover, RF can be suitable for both classification and regression analyses, and it showed interesting results to understand the main drivers of crayfish distribution, fish species richness and the inter-specific interactions between otter foraging behavior and non-native fish species. Lastly, RF also performed well when applied to riparian vegetation. Grouping riparian vegetation species into guilds gave even better results compared to single species modeling.
Habitat time series analysis and UCUT curves, combined with mesohabitat simulation models, were used to define an envelope of naturally occurring habitat events that are harmless to the fauna. These highly informative diagrams represent a three dimensional description of habitat distribution in the continuous duration/frequency space. Hence, environmental flows should fall within this envelope. The method also captured stress conditions that were created by persistent limitation of habitat availability and those created by catastrophically low habitat quantity (e.g. in periods characterized by zero flow conditions in intermittent streams). Furthermore, the application of habitat time series in the context of climate change (Rabbies stream, Italy) and to rivers affected by hydropeaking (Noce River, Italy) allowed the analysis of future habitat conditions and the comparison of hypothetical release scenarios related to possible reduction in hydropeaking intensity.
Till now, mesohabitat suitability models have been built to identify the habitat characteristics mostly used by target fish in perennial watercourses. However, a few studies have been carried out for other aquatic organisms and no applications are currently available neither for crayfish, nor for intermittent streams. In the crayfish study, the mesohabitat scale adapted well to describe habitat use by A. pallipes complex, and mesohabitat predictive models showed interesting potentials for future applications to intermittent streams. Moreover, model extrapolation have been evaluated in Central Italy (Tordino and Saline river basins) and results demonstrated the flexibility of the obtained predictive tools. The proposed methodology also quantifies habitat for aquatic organisms over a range of flows and under zero flow conditions. This constitutes an interesting result of the study and the proposed methodology seems to be adequate to assess e-flows and to design habitat restoration actions in intermittent streams.
We used the proposed meso-scale approach as a benchmark for present and future research studies. As a general rule of thumb, for meso-scale model extrapolation purposes, we can recommend to build biological databases using data from different streams with different morphologies and gradients. Data collected from multiple rivers, distributed at a regional- or at a catchment-scale, can provide a wider range of habitat conditions than those occurring in one single river, and can lead to a more flexible habitat simulation model.