The Siltflux project aims to enhance understanding of suspended silt flux in rivers to establish standards for protecting sensitive Irish catchments. It involves assessing silt reduction benefits from mitigation measures and understanding the ecological impacts of sediment concentrations and flux variations due to land use. The project includes literature review, sediment measurement database creation, methodology validation, and dissemination of findings through publications and workshops.

1. SILTFLUX
Project Objectives
• Increase knowledge and understanding of suspended silt flux in rivers to help set standards
for suspended solids flux and concentrations for the protection of sensitive catchments in
Ireland.
• Assess the benefits of silt reduction that mitigation measures can achieve.
• Understand the relationship between concentrations/flux of silts and the potential for
deposition and ecological impacts in different types of rivers, and under variable land-use
pressures.
Tasks
• Literature Review
• Database of sediment flux measurements
• Validating measurement methodology
• Measurement of sediment fluxes and ecological status in
selected catchments with a range of typologies and
typical land uses.
• Review of benefits of river impact mitigation methods.
• Dissemination via publications and workshops
River sediment is a natural and dynamic component of the river/catchment system, transported as
bedload and/or suspended load, depending on the relationship between flow conditions, sediment
supply and the structure, density, size and shape of materials. In healthy fluvial systems, suspended
sediments or silts (typically <63 μm, but up to 2 mm in diameter in extreme events) provide the basis
for diverse aquatic ecosystems through nutrient cycling and replenishment as well as forming the
contributing materials from which aquatic habitats are constructed in river beds and especially banks.
Too much silt, however, can lead to the obstruction of channels, the smothering of habitats, ingress
into the bed, and reduction of light levels in the water column and at the bed, potentially leading to
deoxygenation and environmental deterioration. The chemically-active silt fraction (<63 μm) can
also act as an important carrier of potentially hazardous nutrients and contaminants, including P and
N, polychlorinated biphenyls (PCBs), dioxins and heavy metals, meaning that effective pollution
management is critically linked to understanding sediment transport and storage pathways.
Team
• Michael Bruen
• Mary Kelly-Quinn
• John O’Sullivan
• Jonathan Turner
• Damian Lawler
• Anna Rymszewicz
• Elizabeth Conroy
• Martin O’Grady

2. Along-stream dynamics
Instrument validations
Catchments instrumented 2014
Instrument inter-comparisons
Testing sediment-sensitive
macroinvertebrate metrics