Rehabilitation of Urban Rivers: 
Modelling the Ecological Risks of River Sediments

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Objectives

This project is a development of another URGENT Project on the River Thame - Modelling River Corridors: the scientific basis for rehabilitation of urban rivers (MRC) - addressing an additional boundary condition for river rehabilitation, the mobilisation and bio-availability of sediment-associated contaminants in relation to flow, water quality and channel structure. The project comprises three research tasks:

  1. Measurement and modelling of sediment-associated contaminant fluxes
    Fine particulate sediments are important in controlling the flux of nutrients and contaminants in rivers. However there is currently a paucity of field based information on the dynamics of contaminant transfer between the sediments and the water column.
  2. Measurement and modelling of the role of biota on sediment-water chemical fluxes
    A range of organisms associated with sediments, both interstitial and surface dwellers, play a major part in locking up and mobilising contaminants. Algal biofilms moderate the sediment water exchange and are variable in species composition spatially and temporally. The overall role of biota in sediment water processes is little known at present.
  3. Development of a module to assess the ecological risk of urban river sediments
    This part of the project aims to integrate the data from parts 1 and 2 into a module providing an analysis of sediment associated pollutant dynamics.

The primary scientific objective is to model the ecological risks associated with urban river sediments.

Location

West Midlands

Approach

Measurement and modelling of sediment-associated contaminant fluxes

Field data obtained from selected reaches of the River Thame will be combined with laboratory data and data from other sources/monitoring programmes. The data will be used to obtain information on, sediment-water partitioning of contaminants, particle size and chemical speciation, particulate movement, timing of resuspension events and calculation of loads and fluxes.

Measurement and modelling of the role of biota on sediment-water chemical fluxes

Fluxes of the selected contaminates will be investigated on different sediment types in fluvaria and mesocosms. Studies will include the influence of burrowers and sediment surface grazers.

Development of a module to assess the ecological risk of urban river sediments

Data from tasks 1 and 2 will be integrated to provide an analysis of sediment associated pollutant dynamics.

Start date/duration

October 1999 Three years

Lead Organisations

University of Birmingham

University of Coventry

Deliverables

  • A reach scale model of sediment-associated contaminant fluxes
  • Provide new data to be incorporated into a generic methodology being developed by the URGENT MRC project to inform decision makers about ecological risks of contaminated sediments
  • Produce results for use in the long-term restoration programme
  • Provide information on benefits and improvements in discharges from Minworth in time for the reduced limits for BOD(ATU), suspended solids and ammonia
  • Contribute to the debate on the long-term future operation of Lea Marston Lakes.
  • Presentations and publication in the Scientific Journals to disseminate new findings

Users

URGENT

Environment Agency

Further details

Further information is available from the following contacts:

Lead Researcher: Professor Geoffrey Petts

Tel: 01214 145518, Fax: 01214 145528, email: g.e.petts@bham.ac.uk 

URGENT Programme Manager: Graham Leeks

Tel: 01491 692203, Fax: 01491 692313, e-mail: gjll@ceh.ac.uk