Study

Effects on riverine bird species of an ecologically sensitive flood alleviation scheme along the River Roding between Abridge and Loughton Bridge, Essex, England

  • Published source details Raven P. (1986) Changes in the breeding bird population of a small clay river following flood alleviation works. Bird Study, 33, 24-35

Actions

This study is summarised as evidence for the following.

Action Category

Employ grazing in artificial grasslands/pastures

Action Link
Bird Conservation

Use environmentally sensitive flood management

Action Link
Bird Conservation

Remove flood defence banks to allow inundation

Action Link
Farmland Conservation
  1. Employ grazing in artificial grasslands/pastures

    A controlled study in 1980-1982 on the river Roding in Essex, England (Raven 1986), found that flood pasture alongside a 1.2 km stretch of the river with grazed ‘flood beams’ (see ‘Use environmentally sensitive flood management’) held a similar density of territories to an adjacent 1.8 km stretch which was not grazed (8-13 territories/km for grazed stretch vs. 6-21 territories/km for ungrazed). Riparian species (sedge warbler Acrocephalus schoenobaenus, Eurasian reed warbler A. scirpaceus and reed bunting Emberiza schoeniclus) were largely confined to the ungrazed section, whilst channel-nesting species (little grebe Tachybaptus ruficollis and common moorhen Gallinula chloropus) were at similar densities in both stretches.

     

  2. Use environmentally sensitive flood management

    A controlled before-and-after study on the river Roding in Essex, England (Raven 1986), found that in 1982 there were more territories and more species of bird on a 3 km stretch of the river that was modified in 1979 to reduce flooding in the area, compared to an adjacent 500 m stretch of river that was channelized in 1974 (52 territories of nine species vs. three territories of two species). The experimental stretch had one bank excavated to create a 0.3 m high shelf (a ‘flood beam’) just above the level of the main channel. This meant that the main channel continued to carry water during dry periods (at a rate of 2 m3/s) but during heavy rains, the beam would carry water as well (at up to 40 m3/s) increasing the width and the flow capacity of the river.

     

  3. Remove flood defence banks to allow inundation

    A controlled before-and-after study on the river Roding in Essex, England (Raven 1986) found that in 1982 there were more territories and more species of bird on a 3 km stretch of the river that was modified in 1979 to reduce flooding in the area compared to an adjacent 500 m stretch of river that was channelized in 1974 (52 territories of nine species on the modified stretch vs three territories of two species on the channelized stretch). The experimental stretch had one bank excavated to create a 0.3 m high shelf (a ‘flood beam’) just above the level of the main channel. This meant that the main channel continued to carry water during dry periods (at a rate of 2 m3/s) but during heavy rains, the beam would carry water as well (at up to 40 m3/s), increasing the width and the flow capacity of the river.

     

Output references

What Works in Conservation

What Works in Conservation provides expert assessments of the effectiveness of actions, based on summarised evidence, in synopses. Subjects covered so far include amphibians, birds, terrestrial mammals, forests, peatland and control of freshwater invasive species. More are in progress.

More about What Works in Conservation

Download free PDF or purchase
The Conservation Evidence Journal

The Conservation Evidence Journal

An online, free to publish in, open-access journal publishing results from research and projects that test the effectiveness of conservation actions.

Read the latest volume: Volume 18

Go to the CE Journal

Subscribe to our newsletter

Please add your details if you are interested in receiving updates from the Conservation Evidence team about new papers, synopses and opportunities.

Who uses Conservation Evidence?

Meet some of the evidence champions

Endangered Landscape Programme Red List Champion - Arc Kent Wildlife Trust The Rufford Foundation Save the Frogs - Ghana Bern wood Supporting Conservation Leaders National Biodiversity Network Sustainability Dashboard Frog Life The international journey of Conservation - Oryx British trust for ornithology Cool Farm Alliance UNEP AWFA Butterfly Conservation People trust for endangered species Vincet Wildlife Trust