The role of the HYPOrheic zone on the transporter-transformer functions of River corridors.

Descripción del proyecto

Mejora de la salud de los ríos mediante el estudio del transporte de sustancias reactivas

La calidad del agua de los ríos está profundamente influenciada por sustancias reactivas disueltas cuyo destino se controla principalmente en la zona hiporréica. Esta interfaz crítica entre el agua rápida del río y el flujo más lento en los poros de los sedimentos del lecho fluvial genera un entorno ideal para las reacciones biogeoquímicas. Las reacciones desempeñan un papel fundamental en la salud de los ecosistemas fluviales. El proyecto HYPOR, financiado por el Consejo Europeo de Investigación, pretende avanzar en nuestra comprensión de cómo la zona hiporréica contribuye y regula el transporte reactivo en los ríos. Al explorar las variaciones espaciales y temporales en múltiples escalas, el equipo de HYPOR incorporará sus efectos a modelos innovadores y ascendentes. Los modelos mejorarán la predicción de la calidad del agua en los ríos y, en última instancia, servirán de base a las estrategias de protección y mantenimiento de los ecosistemas acuáticos.

Objetivo

Reactive substances transported in river corridors undergo several transformations having important implications for the fate of toxic chemicals and the health of fluvial ecosystems. Delivery of substances into the slow and geochemically-microbially rich hyporheic zone delays their downstream transport and promotes opportunities for biogeochemical reactions. The resulting delay and reactivity at larger scales are shaped by the ubiquitous heterogeneity of environmental porous media and the temporal fluctuations that typify river corridors which control transport and mixing limitations in the reactive regions of the hyporheic zone. However, the most widespread upscaling pictures neglect these fundamental aspects, assuming either a transient storage in a well-mixed hyporheic zone or pure advective transport along non-interacting hyporheic streamlines. The paradigm of oversimplification leads to severe shortcomings, such as limited transferability of findings and great uncertainty in large-scale predictions.

HYPOR pursues a paradigm-shift: ground the upscaling of reactive-transport in river corridors on the mechanistic knowledge of the hyporheic dynamics. First, we will improve the understanding of heterogeneity and temporal fluctuations controls through comprehensive numerical investigations at small scales. Second, this will allow to quantify, on a physical basis, the stochasticity in the transport and mixing limitations of point-injections (Green functions) as they encounter reactive regions. The stochastic evolutions of Green functions will be the building block of a novel reactive-transport upscaled model to overcome current shortcomings. Yet, the hidden nature of the hyporheic zone leads to uncertainty. Third, HYPOR will exploit the link between small-scale uncertain properties and physics-based upscaling elements in a new uncertainty analysis framework that propagates uncertainty at small scales onto large-scale predictions, quantifying their reliability.