Sunday, August 20, 2017

Background

River sediment is a natural and dynamic component of the river/catchment system, where it is 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.

Project Objectives

This project, being undertaken by a multi-disciplinary research team in University College Dublin, has the following objectives:

(i) Increase knowledge and understanding of silt flux in rivers to help set standards for suspended solids flux and concentrations for different land uses and for the protection of sensitive catchments in Ireland.

(ii) Assess the benefits of silt reduction that enhancement measures can achieve.  It is also essential to differentiate between effects on fine and coarse sediments.

(iii) 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

Data is collected in near real-time from stations deployed in a number of rivers. These data are monitored and bottle samples are fired remotely in order to capture samples on rising and falling floods. At a number of intermediate stations bottles are also fired automatically in response changes in water level. A sample graph from one station showing the last 5 days of realtime depth and turbidity data is shown below. 

Access to the full data set is restricted to project partners for now but will be made available at a later date. 

Project Contact


Further details of the project can be obtained by contacting:

Prof. Michael Bruen

UCD Dooge Centre for Water Resources Research

School of Civil, Structural and Environmental Engineering

University College Dublin

Newstead, Belfield, Dublin 4, Ireland

E: Michael.bruen@ucd.ie

T: +353 (1) 7163213

Or through direct contact with any of the project team.




This project is funded by the EPA, Ireland



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