Siltation in the Navigation Channel of Patos Lagoon Estuary, Brazil, Considering the Current Configuration of the Jetties and the Channel

Abstract

Abstract The sediment dynamics, mainly the deposition processes, is one of the most important aspects concerning ports. Understanding sediment patterns is vital for port management since it supports the search for strategies that minimize siltation or promote more sustainable management. This study aims to assess the morphological characteristics and siltation patterns of the access channel to the Patos Lagoon estuary, after the modifications made in the jetties geometry and in the channel configuration in the late 2000s. The Port of Rio Grande, one of the largest in Brazil, is located on the west margin of the inlet. Bathymetric data provided by the Port Authority from 2015 to 2020 were used to generate digital elevation models and then assess the net sedimentation rates and the evolution of the channel bottom over time. Results indicate a significant variability of net sedimentation rates. The volume of sediment deposited on the channel bottom in approximately one year was roughly 2.5 times greater than that deposited in 2 years and 3 months. The entrance area, covered by rectangles 3B-4C (which represented 34% of the study area), was responsible for about 50% of the net sedimentation volume in both analyzed periods. The area between jetties (3E-4C) showed major net sedimentation rates in both periods. The analysis of the bathymetric data series was effective in evaluating important morphological characteristics of the channel, and it was possible to identify aspects of siltation patterns and obtain yielded unprecedented results.