Application of the Physical Habitat Simulation System (PHABSIM) to the Rivers of Scotland and Northern Ireland

January 2000

Executive Summary

This research project has three objectives:

  1. to assess the potential of physical habitat modelling as a tool for the evaluation of the environmental impacts of water resource developments and river engineering schemes in Scotland and Northern Ireland
  2. to develop knowledge of physical habitat modelling in Scotland and Northern Ireland
  3. to assess the potential for developing a method to allow rapid habitat assessment of the changes in physical habitat with changes in discharge regime or river morphology in rivers of Scotland and Northern Ireland

Two pilot sites in Scotland (one east coast, one west coast) and two in Northern Ireland were chosen on small to medium sized rivers (5-20m wide) which were in some way typical of the region. Hydraulic modelling at three of the four sites was undertaken. There were insufficient data at the second site in Northern Ireland to undertake full hydraulic modelling. Data requirements, particularly high discharge velocity calibration data, were defined. Physical habitat modelling, using PHABSIM, was undertaken at all four sites. Time series of physical habitat were generated for selected target species/life stages. The work demonstrated that the PHABSIM system is equally applicable to the rivers of Scotland and Northern Ireland, provided normal guidelines and rules are followed. Recommendations for the further development of PHABSIM to better suit the river habitats, discharge regimes and issues in Scotland and Northern Ireland are presented.

The project involved the University of Ulster in field data collection in Northern Ireland. In Scotland a workshop was held with fisheries scientists to develop habitat suitability criteria for trout (Brown and Sea) and Atlantic salmon. It is recommended that expertise in physical habitat modelling in Scotland and Northern Ireland is extended through workshops, training courses and involvement in field projects.

The implementation of rapid systems in other countries was reviewed. Basic elements and data requirements for development of a rapid system for Scotland and Northern Ireland are presented. It is recommended that a rapid method is developed for specific applications (such as scoping studies, or where time and finances do not allow a full hydro-ecological study) as part of a suite of tools available for environmental impact assessment.

Key Words

River habitat modelling, open channel hydraulics, physical habitat, habitat suitability indices, rapid habitat assessment, river flow management

Copies of this report are available from the Foundation, price 35.00, less 20% to FWR members