Managing flooding naturally: Part 2

Managing flooding naturally: Part 2

© Rachel Remnant

There are better, more effective flood management than the supposed silver bullet of dredging

Following the flooding of 55,000 properties in 2007, the Government commissioned the Pitt Review to assess the future of flood risk management and emergency planning. A key recommendation was the Government developing a long term plan towards adaptation and mitigation for climate change, being clear that the UK should prepare for more flooding.

This would require a joined up, strategic approach between central Government, local authorities and agencies, the Crown Estate and the private sector.

Yet since 2007 it is hard to see how a strategic approach has been implemented, and there has been no shift away from measuring flood protection effectiveness purely in terms of capital expenditure in hard flood defences.

Tractor in field

© Clive Chatters

Diverting floodwaters onto farmland

Paying farmers to store floodwater is now on the public policy agenda in light of recent events, but this should not be seen as an alternative to reconnecting rivers with their floodplains. It should also not be assumed that a new watery landscape will by default attract wildlife and enhance habitats. Computer modelling has proven that providing water storage capacity is effective for flood reduction, and our experience has shown it is successful in practice. However flooding intensively farmed land on occasion is not the same, nor as beneficial or cost effective, as successfully reconnecting rivers with their floodplains.

For one thing the model of temporarily storing floodwater on farmland risks providing a conduit for pollutants to discharge into the river. This temporary measure fails to follow the catchment approach, is costlier and could also be damaging for water quality.

It’s worth noting that the primary reasons for water bodies failing their environmental targets for fish is morphology - the form and structure of the river - and sediment. This is another glaring nod to the elephant in the room; land management and diffuse pollution, and modification of the river and floodplain.

In contrast Winnall Moors demonstrated how allowing flood waters to deposit large volumes of fertile river sediment onto grassland, in line with management principles of the historic water meadows, resulted in productive grass growth and an inadvertent nutrient filter for the river.

By all means provide an incentive for landowners to make their land available for flood retention, especially where this lies within the floodplain and if it allows for a withdrawal from maintaining expensive physical embankments to constrain water.

Strategically placed, emergency sites for temporary storage should be selected as part of an integrated catchment approach and not as a way of avoiding long-term investment and stakeholder engagement across river catchments. Equally the land use on such sites should be appropriate to the floodplain and not pose a risk to water quality.

Winnall Moors flooded

© Brian Shorter

The panacea of dredging

Disappointingly, much of the recent debate has focussed around the use of dredging, and those arguing the need for more of this practice to solve all our problems. We at Hampshire & Isle of Wight Wildlife Trust responded in 2014 to Government intentions to increase the scale and reach of dredging, urging other options to be considered.

Dredging is a major contributor to the problem of flooding, not to mention the pollution and habitat degradation of our freshwater environments. Thankfully dredging is not as prevalent in Hampshire as other places, but we are still tackling the harmful legacy of this practice.

Wider evidence and the Environment Agency’s own guidance oppose the practice - yet Defra has just announced that farmers will be permitted to dredge their watercourses without consent or regulation. This is arguably a politically-timed announcement following intense lobbying from some farming and landowning interests, especially considering that deregulation has for some time been advised against by NGOs and Government agencies, including the Environment Agency.

River Itchen at Itchen Stoke Mill

© Linda Pitkin - 2020Vision

Ways forward

The reality we face is that 42% of England and Wales’ rivers have no functional floodplain. A great many more are fragmented and modified beyond recognition - and even our rivers with the highest conservation designations are not being managed holistically to ensure that the river and its floodplain form one integral catchment.

The catchment approach and natural flood management must be integrated into long-term flood management plans. The recent knee-jerk response to major events is uneconomic, unsustainable and raises unrealistic expectations for local communities about the future of their homes and businesses.

This is not to say that engineered measures are not part of the solution. In today’s modern landscape they are necessary - but must be planned as part of an integrated strategy that restores the natural functionality and services of floodplains and their surrounding catchments. This should include addressing land use that exacerbates the rate of water discharge, and reversing the legacy of straightening, raising and embanking our rivers that has physically hindered floodplains from doing the job of flooding.

A must read for any land manager and decision maker the Environment Agency’s ‘Killer Facts’ report – an evidence base for the many benefits of river and wetland restoration. Some of this evidence has been gathered locally in Hampshire, showing once again that the evidence base for natural flood management is growing and is ignored at our peril.