Development of a Sustainable Waterway Masterplan on an Amazon Megariver

Abstract

An interdisciplinary and multicriteria design process was developed to optimize navigation and environmental objectives for the Madeira River in Brazil. A fluvial geomorphology study identified development reaches based on geologic stability with an average periodicity of 57 km. A low water reference plane (LWRP) was established representing a 90% exceedance stage based on bathymetric data collected from the Brazilian Navy and a combination of hydrological analysis and hydraulic modeling. Critical shoals and rock outcrop locations were identified based on a proposed 3.6 m draft at the LWRP. Channel dimensions were established based on Brazilian design criteria with the goal of minimizing potential repetitive maintenance dredging and allowing for adaptive management of the navigation channel location. All but one of the 17 critical navigation sites were located in the upper 640 km of the Madeira River, and site-specific designs using river training structures (dikes) were developed at 4 of the sand shoal locations. These designs were analyzed using a one-dimensional sediment transport model in HEC-RAS to evaluate the potential self-scouring response at the river training structures. The final masterplan includes beneficial reuse of large woody debris for temporary river training structures, permanent (rock) river training structures, rock removal, maintenance dredging with strategic placement to promote channel self-scour, aids to navigation, adaptive channel management, and the development of a national monitoring plan.