Slowing the flow
Is the past being dredged up? asks Mike Handyside, who hears alarming stories of river habitat being destroyed in an attempt to prevent flooding
Mike Handyside hears alarming stories of habitat destruction
SCANDALOUS” AND “perverse” are words that might be used to describe post-war dredging, but the Angling Trust (AT) has used them to illustrate recent flood defence work by Environment Agency (EA) contractors and landowners in six counties. Initial evidence of “wanton-like” vandalism was uncovered on Lincolnshire’s River Idle and a Thames tributary, the River Mole. It has seen essential large woody debris ripped out, while bank-stabilising trees, a home to precious wildlife, have been torn away, as though a hurricane coursed the waterway. The AT quickly alerted 68,000 anglers and a staggering 10,000 engaged with its thread on Facebook, leading to the uncovering of fresh environmental degradation in Yorkshire, Hampshire, Warwickshire and Kent. The flood defence budget in England far exceeds income from rod licences, but is being used in some cases to undo restoration work funded by the latter, a clear case of one department not talking to the other. Royal Tunbridge Wells Angling Society recently received an EA grant of £2,000 for habitat work, including tree planting on the Medway in Kent. Imagine the surprise of its members last December when they helped the EA stock the river, only to observe a separate department of that organisation destroying bankside vegetation just downstream. “The removal of trees and in-river debris is particularly perverse because the EA also funds work to plant riverside trees to shade the water and other projects to install flowdeflectors to create fishery habitat,” commented AT and Fish Legal boss, Mark Lloyd, who added: “It constitutes a scandalous waste of scarce public resources and a disregard for the sensitivity of the water environment.” In the light of the AT’S discovery, I wanted to know if any water-tight commitments had been made by the regulator that would protect other fisheries. Prior to a meeting between the AT and EA, Mark Lloyd told me: “I have had a conversation with the EA and they have agreed to put in place measures to ensure that a) internal staff and b) external “stakeholders” (angling clubs and riparian owners) are consulted before works are carried out by the EA and/or its contractors.” He added, “So, we have won this important point.” I have heard much about the theory of “slowing the flow” and Mark told me that flood defence policy was shifting in favour of natural flood management (NFM). “We would like it [NFM] to go further up the system to where the raindrop hits the field and ensure that soils are absorbent,” he said. I was keen to find out more and discovered that in the murky world of flood research, the EA were studying the evidence. Alastair Driver, national biodiversity manager, showed me a compelling study from Exeter University, in which the “re-wetting” of Exmoor mires by blocking drainage ditches had reduced peak storm flows by a staggering average of 28.5 per cent. As drought threatens the south-east, and excessive abstraction blights the southern chalkstreams, these projects reveal how the ground starts to be a sponge again, despite having been extensively drained. Water is slowly released and the flow is maintained during dry periods. The Pumlumon Project, at the source of the River Severn, blocked ditches, raised the retention capacity of more than 1,000 hectares, held 155,000,000 litres, and lifted the water table by an average of 5 cm. Which begs the question: why is there a political obsession with flood defence, which merely passes floodwaters further down the catchment? The wholesale clearance of in-river woody structures and bankside vegetation is unacceptable and can make the problem worse. The EA’S Fluvial Design Guide states, “This practice often increases the flood risk downstream as floodwaters can arrive at bottlenecks more rapidly.” Surely this work should only, as a last-ditch tool, target critical sites, and not be an excuse for contractors to have a field day, treating lengths of river like building sites, and should be
accompanied by compensatory habitat restoration elsewhere. The EA quotes the Environment Act 1995 and Natural Environment and Rural Communities Act 2006 in its guidance on “Conservation Legal Duties” stating plainly: “We have general duties to protect and enhance biodiversity regardless of specific designations.” This first trickle of projects that slow the flow show what can be done across the UK to prevent flooded homes. I’m not a great fan of so-called “rewilding” – I sit firmly on the dam – but won’t dispute that Mr Beaver holds water back. It is naïve to think that this animal is an answer, but by creating 13 dams on a three-hectare site in Devon, beavers have helped hold back up to 1,000,000 litres of additional water, equating to 33 litres of surface water per square metre of land. During storm events, peak flows between water entering the site (from agricultural land) and leaving were 30 per cent lower on average, with a 29 per cent longer lag time. While anglers worry about the impact of beaver-made obstructions to fish migration upstream, spawning habitat is improved downstream. Not only does natural flow regulation take place, reducing gravel washout, but these rodents have proved, unwittingly, that, on average, water leaving the site contains over 64 per cent less sediment than that flowing in. Survival rates of salmon and trout eggs will be higher in the downstream stretch as a result. With NFM working, even the NFU is now talking about it. Its recently published The Flooding Manifesto makes three demands of government: plan, protect and pay. The farmers’ champion, of course, expects its members to receive income for helping to slow the flow. One word, however, is conspicuous by its absence: “environment”. Other than in the EA’S name, it rarely appears; one mention in the introduction to the credit of farming. Out of nine case studies, only one farmer seems to be properly recognised and valued for wildlife work: “This work means diverse ditch and river bank flora can be found.” Ah, so riverbank vegetation could be important, after all. But in a negative side to the document, the NFU says, “Farmers experience a lack of maintenance of watercourses.” Are they asking for the same destructive flood defence work we have just witnessed in six counties? Or, worse, they surely don’t believe that a fleet of postwar mothballed dredgers are going to be greased up and put to use? Worryingly, the NFU also talks of “extension or establishment of new Internal Drainage Boards” and makes the statement: “These [environmental permitting regulations] enable farmers to undertake essential river maintenance works, such as bank repairs, dredging and habitat recreation with reduced administrative burden. Exemptions and permits must also be developed for groups of farmers or landowners who undertake river maintenance within a catchment partnership.” Surely the word “dredging” doesn’t belong in the same sentence as “habitat recreation”? If groups of farmers were allowed to dredge together in a whole river catchment, would that not constitute wholesale dredging? But looking forward, the NFU may learn lessons from the Netherlands. “Room for the River”, a Dutch government plan, will allow rivers to flood safely at key locations, where agriculture, farm buildings, local roads and infrastructure are protected by bunds and elevated platforms (terps). The project is massive, but so is the threat of future flooding, which is impossible to control with the largest fleet of dredgers, as we face the adversity of an ever-changing climate.
“I’m not a fan of rewilding but won’t dispute Mr Beaver holds water back”
Removing willows will have little effect on this Severn flood. But natural management near the river’s source is slowing the flow.
Dredging should be a last-ditch tool, targeting critical sites only, to prevent homes flooding, such as here in mid-wales.
MIKE HANDYSIDE writes about environmental fisheries matters. A flyfisher for more than 40 years, he has specialist knowledge and extensive experience of rough-stream management
Hampshire’s River Mole: woody debris and trees, critical for aquatic biodiversity, are being destroyed in the name of flood defence.