S3M-8110 Reservoirs (Scotland) Bill

The Deputy Presiding Officer (Trish Godman): The next item of business is a debate on motion S3M-8110, in the name of Richard Lochhead, on the Reservoirs (Scotland) Bill.

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Stewart Stevenson (Banff and Buchan) (SNP): It is a great pleasure to have returned to the Rural Affairs and Environment Committee. I previously served on the Rural Development Committee under your benevolent dictatorship, Presiding Officer. Your performance in that role was so impressive that I was delighted that you expanded your convenership by taking control of the Parliament.

As a late joiner in relation to the bill, I missed the early discussions and the clearly significant engineering contributions that John Scott and others made.

Those members who were in Malawi and missed some of the proceedings should not feel in the slightest bit guilty about it because there the issue of water has a much different character. It is about getting clean, wholesome water in adequate volume to many of the communities in that country. In Scotland, we are fortunate to have sufficient water and simply to have to apply the technical solutions to ensure that we deliver that water to our communities and, through our dams and reservoirs, provide a significant contribution to the amenity of Scotland and the recreation of its inhabitants.

It is worth observing that the extension of the regulation on dams will slightly less than double the number of dams that are covered but, simultaneously, just under one third of those that are currently affected will experience reduced regulation. The bill strikes a proper balance on that.

Deciding that the amount of water that is held in a reservoir that comes under the bill should be 10,000m3 rather than 25,000m3 is quite difficult for the layperson to grasp. To do a little thinking about it, a single cubic metre—1m long by 1m wide by 1m high—is approximately 1 ton in weight because 1 gallon of water weighs 10lb. If 1m3 of water were to be flung over the top of a dam and fall something like 120ft, it would be travelling at 60mph or 70mph by the time it got to the bottom. Members should imagine 1m3 of water hitting an individual: it would be like stepping on to a motorway and being hit by a car.

John Scott rose—

Stewart Stevenson: I suspect that we will get the exact figures from John Scott.

John Scott: Would Stewart Stevenson expect that water to have reached its terminal velocity over that distance, given the gravitational effect on it?

Stewart Stevenson: Let us have a really technical discussion. If it were ice, its terminal velocity in that shape would be approximately 120mph. On the other hand, it is travelling as a liquid, so it will of course disperse and to some extent become aerated. It is a complex issue. Does that not touch upon the very complexities of water? I speak, by the way, as someone who has undertaken parachuting, so I know about terminal velocity and all that sort of thing—it is quite exciting, I have to say.

At 10,000m3, we are looking at holding back something of the order of 10,000 tonnes of water.

Climate change is an important part of the future of not just Scotland but countries around the world. We will see dams that are overfilled because of increased rainfall; as atmospheric temperature rises, that will be one of the consequences. Equally, there will be periods of drought, when there is less water behind the dam.

Concrete is a very old material; the Romans used it 2,000 years ago. Many of our dams are constructed of concrete. As Barnes Wallis discovered when he designed the bouncing bomb, concrete is very strong in pressure but very weak in tension. If you take away the water from behind an elderly dam, there is a risk—although not a huge risk—that the dam might collapse backwards towards the water that previously held it in place. There are a range of risks to which some of our older dams can be exposed. The explosive effect of the bouncing bomb—taking the water suddenly away from behind the dam—is of course what caused the concrete to fall backwards and the water to come forward.

Water is essential for human life. It is worth saying that the well-nourished member of this Parliament could probably survive without food for a couple of months but would survive without water for something less than a week. In paying attention to Scotland’s natural resource that is water, we do something very important indeed.

This is a bill of considerable technical complexity that is simple in its purpose. It is fit for purpose and we should all support it at decision time.

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