Trade-offs and synergies in river-coastal restoration for the Ebro case (Spanish Mediterranean)

By

Sánchez-Arcilla, Agustín
Garrote, Luis
Gracia, Vicente
Cáceres, Iván
Sánchez-Artús, Xavier
Caiola, Nuno
Espanya, Antoni
Espino, Manuel
García, Miguel Ángel
Grassa, José María
Ibáñez, Carles
López, David
Mestres, Marc
De La Peña, José Manuel
Bladé, Ernest
Pernice, Umberto
Puértolas, Laura
Santillan, David
Zemah Shamir, Shiri
Iglesias, Ana

Type

Article

Date of Publication

2025-7-25

Original Publication

Nature conservation

Volume

59

Pages

101--137

Subjects

Coastal roughness , Coastal Wetlands , Ebro Delta , restoration , river-coast connectivity , sediment recycling , Spanish Mediterranean

Contributed by

Pensoft Publishers

Language

English

Published by

Sofia, Bulgaria Pensoft Publishers 2012-

Identifiers

DOI: https://doi.org/10.3897/natureconservation.59.142061

 

Abstract

The paper tackles some of the major challenges associated with coastal risk reduction, based on restored river-delta-coast continuums. The presented approach builds on the Ebro River-Delta system, located in the Spanish Mediterranean coast, where available data and results from hands-on restoration actions provide quantitative evidence on the synergies and trade-offs when implementing restoration. The work addresses the evolution of climatic- and human-induced risks driven by recent deltaic evolution, starting in the 1960s, when socioeconomic development increased and river regulation by large dams in the lower river course started. Such development has driven up freshwater demand, consequently diminishing both liquid and solid discharges in the river system, which has affected the natural deltaic evolution, compounded by sea-level-rise and changes in storminess due to global warming.<br> Evolving erosion and flooding risks (problem symptoms) consider the decrease in sediment input to the delta and the increase in mean sea level (problem origin). To address the origin of the problem, we address sediment availability and transport in the lower river coast and reservoirs, followed by an assessment of sediment transport and deficit at the coastal fringe. The proposed solutions consider reservoir by-pass techniques, sediment mobilisation and downstream transport, as well as downstream transport capacity under present and future climates. Regarding the problem symptoms, we analyse the alternatives to enhance coastal resilience by means of restored coastal roughness resulting from embryonic dunes, lagoons and ridge and runnel topography. The analysis also considers coastal sediment recycling, based on a combination of wind and wave induced transports that provide a natural conveyor belt in dynamic equilibrium.<br> Finally, the paper systematises the main synergies and trade-offs that must be considered in any coastal restoration plan, targeting a low carbon reduction of coastal risks while maintaining the important socio-economic assets in the river-delta-coast system. The conclusion section briefly explores the extrapolation of the proposed approach to other vulnerable coastal regions in Europe.