Nature-based solutions for improving navigation reliability on the Madeira River, Brazil
Authors: Suedel Burton C. , Amorim Renato Souza , Lauth Timothy J. , Creech Calvin T. 
Published: June 2021

Abstract
The Madeira River Navigation and Improvement Project provides a unique opportunity to incorporate nature-based solutions (NbS) into the built environment to promote sustainable communities and water resources infrastructure. The Madeira River has no major physical interventions (river training structures, navigation locks and dams, etc.) to improve navigation, and so is one of the world's last remaining undeveloped megarivers that exhibits natural morphological processes. The objective of this study is to create a safe, reliable, and sustainable navigation channel in the Madeira River. This is being accomplished by designing navigation improvement measures that leverage natural geomorphic processes of the river while minimizing conventional engineering practices that alter the river's morphology. To meet this objective, fluvial geomorphology analysis and hydrodynamic modeling studies have been performed to improve understanding of the morphological behavior of the system. Measures that incorporate beneficial reuse of dredged sediment within the system are being prioritized and incorporated into the study's design. Natural processes are being leveraged through the implementation of an adaptive management process to shape the navigation channel by incorporating the use of dynamic structures using natural local materials (e.g., large woody debris already in the system), a direct application of NbS in practice. This process includes extensive stakeholder collaboration and utilizing nature's energy to balance navigation, ecological, and social benefits along the Madeira River. This project demonstrates that nature-based approaches not only provide navigation benefits but can also provide ecological and social benefits in ways that are sustainable in the long term, consistent with United Nations Sustainable Development Goals (SDGs) and the International Union for the Conservation of Nature's global standard for NbS. Integr Environ Assess Manag 2022;18:115–122. © 2021 SETAC. This article has been contributed to by US Government employees and their work is in the public domain in the USA.
KEY POINTS
The Madeira River is an undeveloped megariver where navigation is substantially inefficient during low water conditions due to sand shoals and rock outcrops, necessitating commercial navigators to implement various measures that increase travel time and costs. The Brazilian government initiated statistical hydrology, hydraulic model, fluvial geomorphology, and sediment transport model studies combined with an extensive stakeholder collaboration process to identify ways in which the river's natural geomorphology could be used to balance multiple benefits. Nature-based solutions identified for implementation included use of large wood, innovative river training and stabilization structures, sediment beneficial use, and reuse of rocks currently obstructing the channel. These study results are being used to identify candidate locations for constructing features in future phases of the Madeira River project that in the long term will substantially limit dredging needs, while enhancing economic benefits and sustaining the river's ecology.