Coupling Rivers and Estuaries with an Ocean Model: An Improved Methodology

João Sobrinho,Francisco Campuzano,Hilda De Pablo,Ramiro Neves

doi:10.3390/w13162284

Abstract

Freshwater sources are essential inputs for regional ocean models covering coastal areas such as the western Iberian Peninsula. The problem is how to include the mixture between fresh and salt water, typically performed by estuaries and in the adjacent areas of river mouths, without unsustainable increases of computational time and human setup errors. This work provides a proof-of-concept solution to both these problems through the use of an offline two-way methodology, where local schematic rivers and estuaries are responsible for mixing river freshwater with salt water of a regional model application. Two different offline upscaling methodologies—which focus on the implementation of tidal fluxes from local domains to regional domains in the context of operational modelling—are implemented in the Portuguese Coast Operational Modelling System (PCOMS) regional model application as well as in a version without rivers. A comparison between results produced by these methodologies, field data, and satellite imagery was performed, which confirmed that the proposed methodology of using schematic rivers and estuaries, combined with the new offline upscaling methodology proposed herein, represents a good solution for operational modelling of coastal areas subject to a high dominance of freshwater inputs.

Highlights

A good model representation of the coastal hydrodynamic processes in the Iberian Peninsula (IP)—namely, those associated with freshwater discharges, such as the West Iberia Buoyant Plume (WIBP) and the West Iberian Central Plume (WICP)—requires the input of all major river sources
These processes are important to subsequent ecological and morphodynamic processes which will affect all human coastal activities and respective coastal management policies, especially relevant for climate change studies focusing on the impact of extreme precipitation events, sea level rise, and storm surges
Modelling System (PCOMS)—a regional mode application—has been running since 2009 without freshwater sources, which has partially compromised its results with regard to surface temperature and salinity near the coast

Summary

Introduction

This is especially true for the Iberian coast, with its many rivers and estuaries serving as natural marine life maternities, and the seasonal upwelling phenomena on the western coast, which is responsible for the replenishment of nutrients and subsequent high marine biodiversity [1,2]

Objectives

Methods

Conclusion