Slowing the rate at which water moves through the upper reaches of a catchment helps to reduce flood peak and lessens the flooding that occurs in communities, towns and cities further downstream, the report says.
It further claims that despite the proven effectiveness of an ecosystem-approach, no trials or catchment-based flood management pilots to date have been undertaken in Ireland, despite evidence that such measures have proven to be an effective way of significantly reducing flood peak.
The report presents case studies of projects in the UK and the Netherlands which it claims have successfully implemented natural flood management . These include the ‘Slowing the Flow’ project in North Yorkshire and the ‘Room for Rivers’ in the Netherlands.
It finds that strong community involvement in addressing flood risk is crucial – as is the involvement of differing interests and State agencies in recognition of the wider environmental co-benefits of natural flood management.
The report points out that profound changes in land-use since the 1960s have caused increased flow of water through each river catchment The result is that heavy rainfall takes less time to reach river channels – and when so much water travels quickly – there is a greater chance of rivers bursting their banks.
‘When water has no place to go but straight to the river channel by the quickest route, we end up having to compensate by widening and deepening channels by dredging. This has been practiced since the 1950s to reduce waterlogging so land can carry more livestock or produce higher crop yields,’ the report states.
By increasing the volume of water that passes through a channel at any given time, dredging increases the so-called flood peak and so exacerbates downstream flooding. Such flooding means that politicians and local authorities are put under pressure to allocate public money for more dredging.
‘Rather than managing flood risk and incorporating wider catchment management, the response involves flood resistance and structural defences. By putting all our eggs in one basket, we are only increasing vulnerability in flood prone areas.’
Restoration and creation of habitats such as flood meadows and reed beds can act as important stores for flood water and can help to encourage reconnection of rivers with their floodplains.
EcoEye RTÉ One: Tuesday February 14 at 7pm