Riparian ecosystems are required to be preserved to achieve the good ecological status. The Water Framework Directive (WFD 2000/60/EC) specifically supports the assessment of new management tools that allow the European Member States to achieve the good ecological status of the river related ecosystems. Within several approaches, a dynamic riparian vegetation distributed model (CASiMiR-vegetation), with a time step of one year, has been selected as a useful first-step tool to achieve the WFD requirements. The model has been implemented into three river reaches with different climatic and hydrologic settings, located in three European countries. Common bases were established in the model set-up. The model was calibrated independently in the Kleblach reach (Drau River, Austria), the Ribeira reach (Odelouca River, Portugal), and the Terde reach (Mijares River, Spain) with simulation periods of 8, 11 and 41 years respectively. The parameters values and the results were comparable between the different countries. The calibration performance achieved high correctly classified instances (CCI ≈ 60%). Additionally, weighted kappa values ranged from 0.52 to 0.66 in distinguishing riparian succession phases. The model behaved similarly in the validation, even offering better results in most cases. This work demonstrates the applicability of this model in This is a pre-copyedited, author-produced PDF version following peer review of the article: García-Arias A., Francés F., Ferreira T., Egger G., Martínez-Capel F., Garófano-Gómez V., Andrés-Doménech I., Politti E., Rivaes R., Rodríguez-González P.M. (2013). Implementing a dynamic riparian vegetation model in three European river systems. Ecohydrology, 6(4):635-651. doi: 10.1002/eco.1331, which has been published in definitive publisher-authenticated form at http://onlinelibrary.wiley.com

Global circulation models forecasts indicate a future temperature and rainfall pattern modification worldwide. Such phenomena will become particularly evident in Europe where climate modifications could be more severe than the average change at the global level. As such, river flow regimes are expected to change, with resultant impacts on aquatic and riparian ecosystems. Riparian woodlands are among the most endangered ecosystems on earth and provide vital services to interconnected ecosystems and human societies. However, they have not been the object of many studies designed to spatially and temporally quantify how these ecosystems will react to climate change-induced flow regimes. Our goal was to assess the effects of climate-changed flow regimes on the existing riparian vegetation of three different European flow regimes. Cases studies were selected in the light of the most common watershed alimentation modes occurring across European regions, with the objective of appraising expected alterations in the riparian elements of fluvial systems due to climate change. Riparian vegetation modeling was performed using the CASiMiR-vegetation model, which bases its computation on the fluvial disturbance of the riparian patch mosaic. Modeling results show that riparian woodlands may undergo not only at least moderate changes for all flow regimes, but also some dramatic adjustments in specific areas of particular vegetation development stages. There are circumstances in which complete annihilation is feasible. Pluvial flow regimes, like the ones in southern European rivers, are those likely to experience more pronounced changes. Furthermore, regardless of the flow regime, younger and more water-dependent individuals are expected to be the most affected by climate change.

Biotic and abiotic interactions between the riparian zone and the river determine relevant hydrological processes and exert control over riparian and bordering upland vegetation types. Vegetation growth and development are mainly controlled by water availability on semi-arid regions so the closeness to the river yields a moisture gradient which clearly determines the boundaries between exuberant riparian zone and semi-arid upland. A mathematical model named RibAV is presented. Its conceptualization is based on the main worldwide ecosystem modelling approaches and field expertise. The implementation of RibAV that is proposed in this paper allows the simulation of the vegetation functional types distribution in riparian zones. An evapotranspiration index (E idx ) obtained through RibAV is used as criterion for long-term plant absence/presence prediction. Two permanent river reaches of semi-arid Mediterranean basins, the Terde reach (Mijares River, Spain) and the Lorcha reach (Serpis River, Spain), have been selected as case studies for the evaluation of the model performance. Several criteria based on the confusion matrix were used to analyze the efficiency of RibAV on the prediction of plant distribution. The model outstanding performance to establish riparian vegetation types distribution and the limit between this zone and the bordering upland is demonstrated in this paper; the strength of the E idx to classify plant functional types in riparian semi-arid environments is additionally proved. This is a pre-copyedited, author-produced PDF version following peer review of the article: García-Arias A., Francés F., Morales-de la Cruz M., Real J., Vallés-Morán F., Martínez-Capel F., Garófano-Gómez V. 2014. Riparian evapotranspiration modelling: model description and implementation for predicting vegetation spatial distribution in semi-arid environments. Ecohydrology, 7: 659-677.

RVDM is an ecohydrological model aimed to study the vegetation dynamics in riparian areas that represents an upgrade respect to previous tools in the way of understanding the riparian dynamics. Important novelties are proposed by this tool, including a high temporal resolution (daily time step), a proposal of a new plant classification approach useful for research and management (successional plant functional types or SPFTs), good representation of the key processes that determine the vegetation dynamics in riparian areas (drought and flood impacts, recruitment, growth, succession and competition), an easy implementation, and feasible inclusion of river morphodynamics in the model implementation (including different daily elevation and soil maps in the inputs). The model implementation in a Mediterranean semi-arid study site resulted satisfactorily (cell by cell calibration accuracy ≥ 65%, cell by cell validation accuracy between 40% and 60%), demonstrating the great potential of this approach for future research and management applications. Although 36 parameters are included in the model conceptualization, the global sensitivity analysis demonstrated that only 8 types of parameters are actually influent.. These parameters are: minimum time since mixed for transition to terrestrial, root depths, transpiration factors, critical shear stress of early stages, minimum biomass required to allow succession, germination minimum capillary water content in the upper soil, effective depth considered for evaporation from bare soil and coverage of pioneers. RVDM model will be a useful tool for gaining a better understanding of the riparian plants behaviour under different ecohydrological conditions.

International audienceClimate change and river regulation are negatively impacting riparian vegetation. To evaluate these impacts, process‐based models are preferred over data‐driven approaches. However, they require extensive knowledge about ecohydrological processes. To facilitate the implementation of such process‐based models, the key drivers of riparian woodland successional pathways across three river reaches, in Austria, Portugal, and Spain, were explored, employing two complementary approaches. The principal component analyses highlighted the importance of the physical gradients determining the placement of the succession phases within the riparian and floodplain zones. The generalized additive models revealed that the initial and pioneer succession phases, characteristic of the colonization stage, appeared in areas highly morphodynamic, close in height and distance to the water table, and with coarse substrate, whereas elder phases within the transitional and mature stages showed incremental differences, occupying less dynamic areas with finer substrate. The Austrian site fitted well the current successional theory (elder phases appearing sequentially further up and distant), but at the Portuguese site, the tolerance of the riparian species to drought and flash flood events governed their placement. Finally, at the Spanish site, the patchy distribution of the elder phases was the remnants of formative events that reshaped the river channel. These results highlight the complex relationships between flow regime, channel morphology, and riparian vegetation. The use of succession phases, which rely on the sequential evolution of riparian vegetation as a response to different drivers, may be potentially better reproducible, within numerical process‐based models, and transferable to other geographical regions