Ian Rotherham: How nature can provide a natural defence to flooding

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AS floods strike yet again, untold impacts of cuts to local authorities, agencies and environmental services have become all too apparent.

Front-line services providing vital co-ordination and long-term support for addressing local and regional environmental issues on the ground have been decimated.

Responses to flood-risk and flooding are examples where countryside planning, woodland, and tree services would help deliver co-ordinated, community-level responses to mitigate problems.

As flood-risk grows year-by-year, pressures on countryside in and around towns and cities become more acute with threats of development and loss of support services.

Trees and woodlands help mitigate and manage flood events. With various and varied locations and forms, trees influence local climatic conditions and potential climate change mitigation.

Of course, trees aid water management in urban landscapes and lower catchments but woodland or tree cover needs to extend back ‘up the hill’.

The environmentalist George Monbiot rightly noted landscape causes of recent problems, with over-grazed uplands and removal of trees from countryside and along watercourses. Yet, governments and other decision-makers seem to ignore the obvious. Serious flooding incidents are generally followed by agency and government-led enquiries and reports but many largely overlook trees and woodlands.

One major casualty of land improvement has been almost total loss in lowland England especially, of once extensive wet woodlands. Broad-leaved woodland substantially improves water quality, reduces low flows and diminishes small floods at local levels. On flood plains, they help mitigate bigger flood events.

So how do we reduce incidents such as York and Cumbria? There need to be programmes to create new wetlands and new woodlands along the rivers.

In towns and cities, it is necessary to provide extensive off-channel storage from small sub-catchments to extensive lowland areas. These will serve to hold back the overspill, and to receive the deluge downstream.

An important consideration for decision-makers is that society must pay for landscape management of water. Indeed, when we fail to take necessary actions, there are societal costs in human suffering, but massive financial penalties too through inflated insurance costs, and plummeting property values in vulnerable areas.

One obvious step is that development and land-use should have positive planning for water to deliver ecosystem services and to avoid real-time financial costs.

Key industries need to address and resolve issues of challenges and benefits such as forestry, farming and cropping within the landscape. It is not enough merely to plant up new lands with trees, but the countryside created must function financially and socially too.

In terms of priorities, there needs to be a focus on critical areas: coastal zones, major valleys and flood plains – and then targeted landscape interventions plus protection of critical infrastructure.

This might include localised reversion of key sites to water storage functions and trees may have a role to play in such areas. However, existing trees might come under threat with such areas targeted for an immediately wetter future.

Across the entire landscape, there needs to be an extensive re-wetting of woodlands combined with targeted new woodlands in the landscape. The latter should be allowed to extend naturally ‘up the hill’, but also across lowland flood plains too. This latter need will mean the re-creation of extensive lowland flood plain woodlands on presently high-value farmland and areas with potential for industrial, commercial and residential development.

The choices will be difficult, but the consequences of failure may be catastrophic with more and repeated episodes of flooding.

Politically and financially (from the business and development sectors particularly), there will be huge resistance. We must learn from recent experiences; planning for ever-more extreme events, taking threats seriously, planning accordingly, and working ‘with the grain of nature, not against it’.

Appropriate sustainable drainage systems, varying with locations and adapted to specific conditions, should be mandatory on all new developments.

Long-term, sustainable solutions must be bigger and bolder. In the meantime, expect more water, more often.

Ian Rotherham is Professor of Environmental Geography at Sheffield Hallam University, and the author of ‘The Rise and Fall of Countryside Management – a historical account’

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