River Ribble and River Brun River Restoration Audit and ...

River Ribble and River Brun River Restoration Audit and Options Appraisal Seb Bentley and George Heritage Overview

Initial Audit

Hydraulic modeling Discussion

2 BACKGROUND Background The main river Ribble is 80 miles

long, Starting near Ribble Head, flowing to Preston and the Irish Sea. Known for its assets but people, forget (sometimes intentionally) about the less exciting areas

URES came about following significant works to improve fish passage in the Calder, including the removal of Padiham and Montford weirs, and fish passes and

easements at Barrowford. After achieving this, the next priority areas had to be identified and addressed through Burnley Background - the problems

Fast Flowing Limited gravels Narrow

Poor habitat Steep Man made Background the opportunities! options in terms of making improvements for wildlife essential part of the project was that we did not impinge on the needs of

people Background Comprehensive study of Calder and Brun

Restricted to maintaining a lined channel for channel stability, flood risk APPROACH

Approach To restore some hydromorphic function and ecological habitat to the

River Calder and River Brun To adjust the present engineering configuration helping to achieve the

Water Framework Directive objectives for the failing rivers Stage one A desk and field based

hydromorphological audit Stage two Options testing and hydraulic modelling

HYDROMORPHIC AUDIT AND ASSET SURVEY Audit and survey

Audit and survey Audit and survey RESTORATION OPTIONS Restoration options appraisal

Current channel geometry Restoration options appraisal

Pool zones Restoration options appraisal

Riffle zone Restoration options appraisal Point bar zone

Restoration options appraisal Apical pool zone

Restoration options appraisal Low flow riffle/rapid reach Restoration options appraisal

Backwater reach HYDRAULIC MODELLING

Hydraulic modelling Study Reaches Hydraulic modelling Proposals Hydraulic modelling 2D Backwater

Hydraulic modelling 2D Pool Hydraulic modelling 2D Low Flow Riffles

Hydraulic modelling What does this mean in terms of sediment? Hydraulic modelling

What does this mean in terms of fish? Assumption In water velocities >0.7m-1 fish will become tired. Fish 0.25m in length

Velocity Distance travelled 0.5

>100m 1 15m

1.5 7m 2

3m 2.5 struggle

Hydraulic modelling 1 in 2yr Velocities Flood Risk Compared pre and post restoration scenarios using 1D-2D linked modelling.

Restored Reaches Restored Reaches . Conclusions

Difficult urban setting Needed to work with sediment dynamics and ecology Audit vital in understanding system Modelling provided confidence in restoration design

Two winters suggests successful dynamic equilibrium