Presentation title

Simon Palmer

Weir Pool Hydromorphology and Hydropower: Tools and techniques for

assessing impacts in deep and fast flowing environments.

IFM 46th Annual Conference: "Extreme Fisheries" - 13-15 October 2015

Introduction

Xiaolangdi Reservoir , Yellow River, China (Telegraph, 2012)

So why do we care about weir pools?

So why do we care about weir pools?

Weir Pool Features

Typically there is a

1. A scour pool

2. A depositional bar (depending upon downstream channel geometry)

Weir Pool Physical Processes

Change in bed shear stress for various structure configurations:

NUMERICAL ANALYSIS OF THE PERFORMANCE OF ROCK WEIRS: EFFECTS OF STRUCTURE CONFIGURATION ON LOCAL HYDRAULICS (Holmquist-Johnson, 2009)

Weir Pool Physical Processes

Walkmilll Weir, River Don, Sheffield, Images courtesy of Google Earth

Weir Pool Physical Processes

Walkmilll Weir, River Don, Sheffield

Hadfields Weir, River Don, Sheffield Images courtesy of Google Earth

Characterisation

• Depth

• Velocity

• Substrate

Substrate: Cooper Scooper

Singer, M. B. (2008) A new sampler for extracting bed material

sediment from sand and gravel beds in navigable rivers, Earth

Surf. Process. Landforms 33, 2277–2284

Depth and Velocity: ADCP

Habitat Suitability:

Hydropower Effects: The Queen goes Green

Romney Weir: Images courtesy of Jackson Civils

Potential Hydropower Effects: Scour

Potential Hydropower Effects: Sedimentation

Potential Hydropower Effects: Attraction Flow

Adapted from Larinier (2002)

Turb

ine

Turb

ine

Conclusions

• Weir and weir pool geometry and sediment regime interact to

control the diversity of habitat

• Specialist tools such as the use of ADCP technology and up

scaled sediment samplers were required to successfully

characterise the habitat.

• The two primary effects of hydropower on hydromorphology

are scour at the outfall and fine sediment deposition in the

depleted zone

• The effect of connectivity are likely to be considerably more

important than those related to localised changes in

habitat.

Thank you for listening