Sir, – In a recent article in The Irish Times on the decision to dredge the Shannon, Minister of State for Flood Relief Sean Canney was quoted as declaring "we must make room for the river" ("Major plan announced by Government-appointed group to dredge Shannon" , December 9th).
I can only presume the Minister was referring to the Dutch approach to managing flood risk called Ruimte voor de rivier ("room for the river").
However, making room for the river involves significantly more than just dredging. In the Dutch model, dredging is only a minor component of flood management. If we look at the Dutch model, making room for the river involves flood attenuation, accommodating water by working with and enhancing natural processes, and restoring the landscape so as to give space to the river to flood safely. Making room for the river also involves incentivising land owners to allow their lands to flood, working with communities to formulate alternative solutions to living with flood risk, and if necessary, relocating homeowners from vulnerable, flood-prone areas. Making room for the river means that we remain flexible in how we adapt to flood risk under climate-changing conditions.
If the concept is now being applied here in relation to how we choose to manage flood risk, it is important that it is used appropriately and correctly. Applying the concept in such narrowly defined terms is misleading and achieves nothing in advancing the conversation, or the policy response to flood-risk management in Ireland. – Yours, etc,
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CATHERINE DEVITT,
Dublin 4.
A chara, – With depressing predictability, the State has agreed plans to dredge the Shannon. There is also an acknowledgment that “we must make room for the river”. Presumably, that “room” is to be found in a southward direction by means of dredging. In a rather bizarre statement by Seán Canney, the plan is to take out “some of the stuff, the silt and the vegetation that has taken over”. What next, maybe we’ll hear that fish have also taken over?
Mr Canney goes on to tell us that the OPW spent €5 million clearing the Shannon tributaries in 2016, but not the main channel itself. He claims that the Shannon will become clogged in 20 years if not dredged in the immediate future.
He may, possibly, be correct in this assertion, but perhaps not the mechanism. It is precisely because of the drainage of the Shannon tributaries that the main channel has an excessive sediment load. Under normal unmodified conditions, the tributaries would deposit their sediment in their alluvial floodplains. However, dredging has severed this process by isolating the tributaries from their floodplains. Consequently, the sediment load is deposited downstream in the Shannon main stem, thus reducing discharge capacity and increasing flood risk.
In the longer term, it would be considerably cheaper for the taxpayer and less destructive to the Shannon's wildlife for the State to purchase agricultural land, peatlands, etc, in the floodplains of the Shannon tributaries and allow them to flood according to the natural cycle of rivers. This would also mitigate the need for the expensive "annual maintenance" that would be required ad infinitum after new dredging.
However, it is unlikely that the sustainable and progressive approach will find favour because this is less likely to keep the Minister in office compared to the sight of a digger in the river.
Mr Canney may be no geomorphologist, but he is clearly an adept politician. – Is mise,
R Ó BRIAIN,
Baile Átha Cliath 7.