gauging weirs - addressing the needs of different stakeholders

rrc@therrc.co.uk 01234 752979 www.therrc.co.uk

Gauging Weirs - Addressing the needs of different stakeholders

Dr Di Hammond

Senior Projects Advisor

rrc@therrc.co.uk 01234 752979 www.therrc.co.uk

Overview

• Why do we need to measure flow?

• Who uses flow data?

• Other considerations

• Why use a structure?

• Dis-benefits of structures

• What are the alternatives?

rrc@therrc.co.uk 01234 752979 www.therrc.co.uk

Why do we need to measure flow?

• Strategic

– Long term trends

– Climate change

• Operational

– Flood

– Drought

– Water resource management

rrc@therrc.co.uk 01234 752979 www.therrc.co.uk

Who Uses Flow Data?

• Water resource managers

• Flood defence managers

• Water companies

• Academics and students

• Policy makers

• Climate change scientists

• River restoration practitioners

rrc@therrc.co.uk 01234 752979 www.therrc.co.uk

Some Other Considerations • Archaeology

• Subsidence

• Water level maintenance

• Aesthetic appearance

rrc@therrc.co.uk 01234 752979 www.therrc.co.uk

rrc@therrc.co.uk 01234 752979 www.therrc.co.uk

rrc@therrc.co.uk 01234 752979 www.therrc.co.uk

rrc@therrc.co.uk 01234 752979 www.therrc.co.uk

Why use structures to measure flow?

• Accuracy with a Weir Structure – Larinier fish pass 3%

– Crump and flat v weirs 3-6%

– V Notch thin plate weir 6%

• Structureless measurement techniques accuracy – Multi path time of flight ultrasonic gauges 7-10%

– Doppler flow gauges 10%

– Electromagnetic flow gauges 10 – 15%

– Open channel 10%plus

rrc@therrc.co.uk 01234 752979 www.therrc.co.uk

rrc@therrc.co.uk 01234 752979 www.therrc.co.uk

rrc@therrc.co.uk 01234 752979 www.therrc.co.uk

The Dis-benefits of structures

• Geomorphological effects

• Fish passage

• Habitat

• Flow variability

• Flood issues

rrc@therrc.co.uk 01234 752979 www.therrc.co.uk

What are the structureless alternatives for flow measurement?

• Ultrasonic

• Doppler flow gauge

• Electromagnetic

• Open channel

rrc@therrc.co.uk 01234 752979 www.therrc.co.uk

rrc@therrc.co.uk 01234 752979 www.therrc.co.uk

rrc@therrc.co.uk 01234 752979 www.therrc.co.uk

rrc@therrc.co.uk 01234 752979 www.therrc.co.uk

rrc@therrc.co.uk 01234 752979 www.therrc.co.uk

rrc@therrc.co.uk 01234 752979 www.therrc.co.uk

Scaling up our Aspirations for River Restoration and

Management

14TH ANNUAL NETWORK CONFERENCE

The RRC would like to thank the sponsors of the RRC Annual Conference 2013 who support discounted places