Tributary contributions to sediment deposited in the Jacul Delta, Southern Brazil

The Jacul Delta drains into Lake Gualba which is the main source of water for more than two million people in South Brazil and has suffered from pollution with heavy metals and phosphorus. The objective of the current research is to demonstrate how the use of sediment source tracing techniques, in combination with sediment flux monitoring, can improve understanding of the sediment source contributions to one of the largest lakes in South America. The sediment flux monitoring results were based on data obtained from 12-years of records of water flow and suspended sediment concentrations. The sediment source fingerprinting approach was based on the use of geochemical tracers. Based on the study, the respective contributions of the tributaries to the sediment in Lake Gualba were estimated to be as follows: the Jacul River (median of 54% - interquartile range (IQR) 34-71%), the Cal River (12%, IQR 7- 16%), the Sinos River (5%, IQR 1-20%), and the Gravatal River (16%, IQR 10-30%). These results are similar to those derived from the sediment flux monitoring, namely: the Jacul River (70%), the Cal River (19%), the Gravatal River (4%), and the Sinos River (7%). These results demonstrate that the sediment source fingerprinting approach combined with sediment flux monitoring can provide a useful means of estimating the respective sediment contributions from individual tributaries in large and complex delta systems and may provide a powerful tool to guide water resource management. (c) 2022 International Association for Great Lakes Research. Published by Elsevier B.V. All rights reserved.

Automated summary

The objective of this research is to improve understanding of sediment source contributions to one of the largest lakes in South America by using sediment source tracing techniques and sediment flux monitoring. The results demonstrate the effectiveness of this approach in estimating sediment contributions from individual tributaries in large and complex delta systems.