Session C1: Assessing Longitudinal Connectivity Affected by Cross-Sectional Barriers in a Riverine Bidirectional Network

Abstract: Disruption of longitudinal connectivity is a main problem in most of the world rivers. Spain, as a country with one of highest rates of cross-sectional obstacles per river, needs a strategy to restore longitudinal connectivity in riverscapes. Graph theory based approaches have proven as a suitable tool to measure the connectivity in the landscape. Unlike terrestrial habitats, where it has been profusely used, riverine systems still remain scarcely studied under this focus. There is a need to adapt the currently available knowledge on terrestrial habitat connectivity assessment to the management of river networks. In our study the broadly used Probability of Connectivity Index has been used to assess the global connectivity loss due to artificial obstacles (dams and weirs) in two medium sized river basins networks in Central Spain (Cega and Pirón). However, unlike previous studies, this time both differential downstream and upstream passability (directional connectivity) has been accounted through a purposefully adapted version of the Conefor software package. Passability has been quantified for every obstacle by means of an index that takes into account the requirements of every fish species in the community. This procedure ranks all the obstacles in the river network according to their individual contribution to the global loss of connectivity (upstream and downstream). It is therefore a tool that provides river basin management plans (RBMP) knowledge on the expected global benefits of the removal of each obstacle

Linking environmental flows to sediment dynamics

© 2017 The Authors. This is a policy discussion paper aimed at addressing possible alternative approaches for environmental flows (e- Flows) assessment and identification within the context of best strategies for fluvial restoration. We focus on dammed rivers in Mediterranean regions. Fluvial species and their ecological integrity are the result of their evolutionary adaptation to river habitats. Flowingwater is themain driver for development and maintenance of these habitats,which is why e-Flows are needed where societal demands are depleting water resources. Fluvial habitats are also shaped by the combined interaction ofwater, sediments,woody/organicmaterial, and riparian vegetation.Water abstraction, flowregulation by dams, gravel pits or siltation by fine sediments eroded fromhillslopes are pressures that can disturb interactions among water, sediments, and other constituents that create the habitats needed by fluvial communities. Present e-Flow design criteria are based only on water flow requirements. Here we argue that sediment dynamics need to be considered when specifying instream flows, thereby expanding the environmental objectives and definition of e-Flows to include sediments (extended e-Flows). To this aim, a hydromorphological framework for e-Flows assessment and identification of best strategies for fluvial restoration, including the context of rivers regulated by large dams, is presented

Utilización de Mapas de Conocimiento Difuso (MCD) en la asignación de prioridades de la restauración fluvial:Aplicación al río Esla

La gestión de los ecosistemas fluviales atañe a diferentes grupos de interés (i.e., gestores, profesionales, académicos y usuarios) que tienen concepciones y objetivos diferentes en relación al mismo. Diversos procedimientos se han ideado para permitir la participación de estos actores en la planificación hidrológica; si bien los procedimientos con puesta en común de intereses y responsabilidad compartida en la gestión se muestran más sostenibles ecológica y temporalmente. La modelización matemático-física de los sistemas fluviales es muy aconsejable en el planeamiento para poder plantear escenarios y predecir soluciones de consenso, pero no siempre se tiene información suficientemente para realizarla. En estos casos, los modelos semánticos o meta-modelos pueden ser alternativas válidas para simular estos sistemas complejos multi-criterio con múltiples decisores. En particular, los Mapas Cognitivos Difusos (MCD) se presentan como una herramienta que facilita la modelización de los sistemas ecológicos, sus funciones y servicios. Los MCD son redes de conceptos entrelazados mediante relaciones causales. La ordenación espacial de los conceptos y la aplicación de reglas de lógica difusa facilita la integración de MCD generados por diferentes expertos, produciendo mapas de consenso. Una vez establecida la matriz de adyacencia del MCD, se somete al modelo a distintos escenarios de actuación simulándose los efectos en las funciones y servicios ambientales. En el presente trabajo se aplican los MCD en el estudio de alternativas de restauración fluvial del río Esla, donde participan 7 decisores pertenecientes a 3 grupos de expertos. Como resultado de la modelización del río Esla se obtiene una previsión de los efectos esperables en el ecosistema fluvial ante distintos niveles de actuación restauradora