Study of Biogeomorphic Trajectories as Baseline for Process-Based River Restoration in a Large River-Floodplain System: the Duero River (Spain)

Abstract:

When planning river restoration measures, the crucial starting point is investigating how a river-floodplain system deviates from a reference condition or benchmark. Since most large riverslack comparative pristine reaches nowadays, historical analyses of the studied river system canproduce valuable reference data for reconstructing the character of the riverine system prior tomajor alterations; particularly, the time-based perspective of river-floodplain processes is key inunderstanding its evolution until its present situation.

Therefore, this study follows a methodology based on a temporal evolution approach(diachronic analysis) of hydromorphological and vegetation dynamics in a large river system.Habitat maps of a 14.4 km long section of the Duero River upstream Zamora (Spain) wereintersected with GIS-based tools. Patches showing trajectories of anthropization, changeless,progression and regression allowed for the identification of natural and human-inducedprocesses over the time period between 1945 and 2017. Results show that this Duero Riversection is a good example of the situation of many large rivers, where natural rejuvenationprocesses, which involve the re-setting of floodplain habitats (e.g. channel shift, erosion andvegetation rejuvenation), are now highly impaired and whose recovery should be the objectiveof future process-based restoration measures.

This study is framed within the DRAINAGE project for the integral management of flood risk(http://drainage.cedex.es/), funded by the Spanish Ministry of Science and Innovation throughthe State R + D + i Program oriented to the challenges of society 2017 (Programa Estatal deI+D+i Orientada a los Retos de la Sociedad 2017 del Ministerio de Ciencia e Innovación deEspaña). This process-based restoration perspective is especially relevant in promoting theresilience of the river system in the current context of climate change. Specifically, within theDRAINAGE project, with the recovery of natural biogeomorphic processes, an increase in thehydraulic retention capacity of the floodplain is also pursued, balancing objectives of natureconservation and prevention of flood control.