Belford Catchment Proactive Flood Solutions: Storing and attenuating runoff on farms Using FIRM plan

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Belford Catchment Proactive Flood
Solutions-Storing and attenuating runoff on
farms (Using FIRM plans)
1Mark Wilkinson, 1Paul Quinn, 2Phil Welton and
1Ian Benson 1School of Civil Engineering and
Geosciences, Newcastle University.2Environment
Agency, Newcastle upon Tyne
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What are Proactive FIRM plans?

• Farm Integrated Runoff Management (FIRM) plans
  are committed to the concept of the storage,
  slowing, filtering and infiltration of runoff on
  farms at source.
• The best place to control runoff is at source
  and within hours of the runoff generation. These
  spatial and temporal windows of opportunity are
  not being fully exploited in environmental
  management.
• If a typical farm or small catchment can
  sacrifice 2-10 of the landscape to runoff
  storage
• and mitigation features then
• the properties of the runoff
• regime can be radically altered.

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FIRM plans a multipurpose solution
N P pH etc.
Water quality improvements
Trap sediment
Runoff attenuation features
Mammal Habitat
Bird Habitat
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Background to FIRM in Belford

• Approached by the EA to apply FIRM plans in the
  Belford Burn Catchment
• Normal flood defences
• can not be deployed in the
• village owing to the
• constricted channel.

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• Belford Burn catchment 5.7km2

• 35 properties and several local businesses at
  risk within the floodplain areas

• Belford North Northumberland, UK
• A number of flooding problems in recent years

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Belford Proactive flood solutions

• Task 1 Install stream gauges, a raingauge and
  a piezometer to understand the catchment
  hydrology before, during and after construction
  (COMPLETE).
• Task 2 Build a pilot pond to demonstrate the
  idea of a runoff attenuation feature (COMPLETE)
• Task 3a Roll out more runoff attenuation
  features across the catchment (20 40).
• Task 3b Hold stakeholder meetings to inform
  the farmers and the villagers of the work that is
  going on.
• Task 4 Examine the effect the features are
  having to wildlife, water quality and sediment.

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Belford and hydrometry location
EA flood warning
Wood outlet gauging station
PONDS 1 3
Pilot pond site
Pheasant feeder gauging station
Piezo
Top field gauging station
Raingauge
(areal pictures taken from Google earth)
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.and just shortly after construction
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5th 7th September 2008 storm
During the 5th 7th September the North-East of
England was inundated with rainfall which caused
flooding throughout the region

• 24hr max rainfall was 72mm a return period of
  28 years for this storm
• 36hr max rainfall was 94mm  a return period of
  48 years for this storm

• FLOOD DAMAGE
• Only one house was flooded in Belford and all
  roads were accessible.
• Last summer, a smaller event caused flooding to
  10 properties in the village

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The Pilot pond (a.k.a. the whiskey barrel)
The pilot pond was constructed to show the FIRM
concept. The pilot pond collects both runoff and
takes high flow water from the stream.
The weir
The pond
The barrier is constructed from sustainably
sourced wood which is leaky allowing the pond to
drain quickly. Total storage capacity of the
feature is 800m3
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The pilot pond - water level data from the
September 2008 flood
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Flood peak travel time before and after the
construction of the pilot pond

• The time of travel of the peak discharge was
  calculated between the weir at the pilot pond and
  a level gauging 1.3km downstream (pheasant
  feeder)
• Based on four flood events before construction
  of the pilot pond the average time of travel of
  the flood peak was found to be 27 minutes
• The average travel time of the two flood peaks
  that occurred after construction of the pilot
  pond and spill weir was 40 minutes.
• Data suggests that Pond 0 has delayed the flood
  peak. However, more storm data is required.

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Feature 1 Inaugural pond

• Bund created by scraping soil on site. Channel
  bank is lowered to allow high flows to spill into
  the pond. Pond then drains quickly.

Spring 2008
29th August 2008

• Capacity of feature 450m3

6th September 2008
8th September 2008
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Feature 2 The old dam site

• Old badly maintained dam was strengthened. Outlet
  pipe and spillway installed.

1st September 2008
Spring 2008

• Capacity of feature 800m3

8th September 2008
6th September 2008
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Feature 3 Burnside pond

• Bund created by scraping soil on site. Channel
  bank is lowered to allow high flows to spill into
  the pond. Pond then drains quickly.

6th September 2008

• High flow peak from stream spills into pond

• Soil bund dam 1m high at highest point

Spring 2008
8th September 2008
6th September 2008

• Capacity of feature 600m3

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Early estimations of flood peak reduction

• Pilot pond - stores 800m3 of floodwater in a
  catchment of 0.5km2.
• Represents a total rainfall of 1.6mm stored from
  that 0.5km2 sub-catchment.
• The current onset of flooding in Belford is from
  a 1 in 5 year event. This represents a flow of
  4.56m3/s. The flooding in Belford is very flashy
  due to the small nature a steepness of the
  catchment. Flood durations are typically less
  than 2 hours.
• The volume of flow assuming 4.56m3/s
  (approximation) for 2 hours (7200 seconds) is
  32,832m3 for the 2 hour duration.
• By taking out 2,800m3 from the first 4 sites
  represents a reduction in flood flow of 0.4m3/s
  or 8 of the 1 in 5 year event.
• It could be assumed that for every 7200m3 stored,
  the flood peak in Belford can be reduced by
  1m3/s.
• If we look at the 1 in 25 year event, the peak
  flow is 7.04m3/s. By reducing this from the 5
  initial sites by 0.4m3/s takes the flood flow to
  a 1 in 20 year event.

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Cost effectiveness estimations for flooding

• Remembering that it could be assumed that for
  every 7200m3 stored, the flood peak in Belford
  could be reduced by 1m3/s.

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and 20 40 more features to come
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Summary

• After an extensive consultation process with the
  EA (11 different officers) a system for
  constructing runoff attenuation features is in
  place. Features are now being constructed
• September 2008 flood provided a good test to the
  ponds which helped to reduce the flood peak in
  Belford.
• Ponds are multi-purpose
• Belford is a pilot for upscaling FIRM plans. It
  is hoped one day that these features will be
  built and managed by the farmers with payment
  coming from the entry/higher level stewardship
  schemes.

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Questions?
www.youtube.com/proactivefarms