# Water Salinity Impacts Aggregation, Settling, and Deposition of Fluvial Sediment

## TL;DR

This paper shows how water salinity affects how river sediment clumps and settles, which is important for wetland restoration efforts.

## Contribution

The study reveals a novel link between wetland water salinity and fluvial sediment deposition processes.

## Key findings

- Higher salinity increases sediment aggregation and settling due to electrical double-layer compression.
- Increased salinity reduces the packing density of deposited sediments, potentially affecting land stability.

## Abstract

Global wetlands have
declined by 21–35% since
the 18th century,
losing approximately 1.3 million square miles. Infrastructure development,
specifically, river channelization via levee construction, is a driver
of this decline. In response, large-scale river diversion projects
have been proposed to enhance sediment deposition and stabilize coastal
wetlands. However, the role of aquatic chemistry in controlling the
fluvial sediment deposition remains elusive. Here, we demonstrate
that land formation by fluvial sediment deposition is intrinsically
linked to wetland water salinity, which influences the sediment aggregation
and settling kinetics. In laboratory experiments, Mississippi River
sediments were exposed to a range of salinities that mimic the conditions
in Louisiana wetlands. Our results show that higher ionic strength
accelerates sediment aggregation and settling due to electrical double-layer
compression while also reducing the packing density of deposited sediments,
potentially impacting land stability. These findings point to the
importance of incorporating salinity effects to optimize sediment
diversion strategies.