Agri-structure as Infrastructure

Flood Alleviation Control by ‘Roughness’ as well as by ‘Form’

This article arises from a recent  London Forum seminar and seeks to raise awareness of engineered landuse (‘roughness’ control) to mitigate the effects of extreme flooding.  The approach was touched on by the ‘Local-Strategy’ panel, in particular by the NFU,  but, despite questions from the audience,  no financial framework was put forward to link the COST of such rural work with the flood alleviation BENEFIT accruing.

Flood Management is effectively dynamic control of water:  the two primary levers of shallow water hydraulic control are elevation and roughness.   In analysis of such hydraulic flow, elevation (and slope) assign force to flood flow, with resistance (roughness) adjusted supportively to achieve solution (of analysis) and calibration. Whilst both parameters are ‘given’ by our natural environment, for strategic/built schemes it is more usually the former which is developed for community and private resilience (levees, dams, structures, etc).

But is it defendable to focus FRM on this expensive (built, smooth and often ugly) ‘Form-based’ approach, when the natural sibling ‘Roughness’ is delegated to a mere reactive role?  Roughness grows naturally. It forms not only usefully porous capital assets, but also puts down roots to achieve self-maintenance. Roughness can be cropped for food and energy. Whilst it has to be managed and dense for good control, it does not have to be built.

So argument here is in defence of ENGINEERED roughness both for community benefit and for resilience (when river conveyance becomes over-zealous as in flood);  not forgetting that rivers are primarily  conveyors of good water which for the most part is benign – good for both life support and wellbeing.

The November 2015 WEETF seminar certainly re-examined problems and priorities of flood management, and a few (NFU) slides did indeed illustrate the helpful role landuse can have in this respect.  However the potential of the monetary mechanisms to exploit landuse good practice was not explored. In particular:-

  • Inclusion of FRM works in RDP’s (& Glastir)
  • CAP Pillar 2 definition of Flood Alleviation works as community development gain
  • (Urban corridor) Insurance sponsorship as best practice
  • Urban local authority sponsorship as best practice
  • Water Supply Industry obligation (particularly of catchments resourcing urban clean water)
  • The new Somerset Rivers Authority financial framework as good practice
  • Drainage Board/District extension (to link green storage with managed rural drainage)

It would promote the several references to the multiple benefits of strategic vegetation (pollution control, wildlife corridor, flood alleviation, water quality, etc),  if effective monetary mechanisms  could be identified which link Rural Development COST with downstream community BENEFIT . For example, in many catchments, the inverse of the Somerset formula could be applicable,   ie  the concept/mechanism of  ‘negative‘ levy (aka  RDP grant) for landowners who deliver community FRM gain.

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Stream Networks reveal NFM Opportunity

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Flood Alleviation within Rural Development

This gallery of images records a 2014 survey of FRM/’ALFA’ potential along the rural England-Wales border. Evidence exists there of opportunities, primarily by attenuation, to exploit CAP Pillar 2 incentive for community FRM investment by Adaptive Landuse (Ecosystem Service). Approaching 100 locations of interest are identified. Such sites, when characterized, should be visible also to spatial targeting software.

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Character (photo-tag) updates are in progress by

  • agristructure_opportunity (porous structural features)
  • downstream_risk
  • floodplain_opportunity
  • green_storage
  • infrastructure_opportunity
  • landuse_risk
  • pinch_point
  • roughness_opportunity

Keywords:

SCIMAP, Atrepo, Offa, Alfa, Flooding, NFM, Opportunity mapping, Connectivity mapping, Risk Mapping

 – – – – – –   ‘ALFA’  acronym courtesy EU/NERC projects  – – – – – –

(‘more info >>’  points currently to Atrepo archive)

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Guilsfield Watershed 40km2

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European Landuse Project


‘ALFA’ Locations of interest

Blue icons for background, Red for study sites and “M” icons for 2D analysis pilots.
ALFA acronym courtesy EU/NERC projects

where

are surveyed and opportunities exist for

Attenuation modelling of Landuse,  Flood Alleviation,  green storage and lower (peak) stage.

* * * * * * * * *

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Keywords:Hydraulics; Biodiversity; Amenity; Infrastructure; Corridors;  Multiple Benefit;  PES;  Sustainable Engineering
Pending: R Hodder,  R Parrett,  Boscastle (2004); Helmsley (2005), Morpeth (2008), Cumbria (2009); Cornwall (2010); Christmas (2012)
Acronym Tags:  NERC, EPSRC, NH, TAP, LWEC, CS, SUNR, SISB, FRMC, FREE, CWC, RELU, CORFU

Hybrid grass ‘could reduce flooding impact’

Mark Kinver,  BBC News Environment reporter, writes:-

“A hybrid farmland grass, developed by a team of UK researchers, could help reduce flooding, a study has shown. A team of plant and soil scientists said tests showed the new cultivar reduced run-off by 51%, compared with a variety widely used to feed livestock. They added that rapid growth and well developed root systems meant that more moisture was retained within the soil rather than running into river systems.

Slowing the flow to reduce peak flows

High Friction Grass – photo courtesy Dr Kit McCleod, James Hutton Institute

The novel grass is a hybrid of perennial ryegrass (Lollium perenne) – which is widely planted by farmers for grazing livestock – and meadow fescue (Festuca pratensis), which has environmental stress-resistant characteristics.

Co-author Kit Macleod, senior research scientist at the James Hutton Institute based in Aberdeen, said a long-term project had been developing novel forage grasses but their environmental benefits had not really been tested.”

More on greener grass (courtesy BBC online)  http://www.bbc.co.uk/news/science-environment-22307863

The findings appear in the journal Scientific Reports.

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Flood Risk and Green Storage

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