Towards integrated modelling of Watershed-Coast System morphodynamics in a changing climate: A critical review and the path forward

Abstract

The term "Watershed-Coast System" refers to the entities consisting of watersheds and the areas adjacent to their outlets, where sediment delivery from rivers and natural streams plays a key role in the evolution of coastal morphology. Climate change implications in these complex systems are projected to extend from morphological to ecological and socio-economic ones, threatening ecosystems, cultural heritage, settlements, infrastructure and human life itself. Accordingly, the design of protection and adaptation measures that will enhance resilience against relevant hazards has emerged as an imperative need in both research and policy. Understanding how watershed and coastal processes are intertwined into a web of dependencies that shape morphology evolution, how climate change would affect watershed/coastal dynamics and how scientists can design effective protection/adaptation measures, can only be achieved on the basis of integrated modelling systems that simulate the morphodynamics of the watershed-coast continuum. Within this context, the present work provides a critical review of the theoretical background and state-of-the-art of research on the modelling of Watershed-Coast System morphodynamics, and through this: (a) presents a scheme for the integrated modelling of Watershed-Coast System morphodynamics in a changing climate and analyses its core aspects, (b) proposes a methodological framework for adapting integrated modelling approaches for management and engineering purposes, (c) identifies and evaluates the major scientific and modelling challenges ahead, and (d) systematises the path towards informed decision-making for building resilient Watershed-Coast Systems by bridging the gaps between science, society and governance. The overall approach is applied as proof-of-concept to a hypothetical case study of a Watershed-Coast System located in the Mediterranean.

Keywords: Climate change; Geomorphology; Morphodynamics modelling; Resilience; Watershed-Coast Systems.