1. Is Glasgow at risk from flooding?
Glasgow is at the upper limit of the tides flowing from the Firth of Clyde. The height of the tide varies with the positions of the moon and sun but can be greatly increased by what is known as a tidal surge. Severe weather conditions to the south and west of the Firth of Clyde can cause a surge that will run up the Firth and upstream as far as Glasgow. If this was to happen at the same time as a high tide, the water level would rise above the level of the quay walls in the city centre. This is the major threat to the city.
This risk is often described in terms of flood return period as a 1 in 200 year event. This does not mean that it will only happen once in a hundred years but means that there is a 1 in 200 chance of it happening in each and every year. This is known as a ½% risk.
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2. If there is a major inundation from the River Clyde how much of Glasgow would be affected?
The direct effect of major inundation from the River Clyde would be to the areas immediately adjacent to the river and would flood areas that are at a similar level to the quay walls. This would include the roads in the city centre along the edges of the river and flat areas such as car parking close to the river.
Flooding could also occur indirectly, either from river water flowing back up drains or through underpasses to low ground or from rainwater unable to drain to the river because of the high river levels. This secondary flooding could extend for a considerable distance back from the river and could affect large parts of the city centre and transport network.
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3. What is the City Council/Scottish Executive doing to protect the city and other communities along the Clyde?
Using consultants, the City Council, has investigated methods of protection from the risk of flooding. Glasgow City Council Land and Environmental Services has subsequently published the River Clyde Flood Management Strategy, River Corridor Supplementary Development Guide (PDF 2,924k) which was presented to the Executive Committee in September 2007 and has secured approval.
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4. How much will this cost and how long will it take?
The cost of the solution will depend on its final form and scale but very early estimates have ranged from £50M for the simplest and smallest solution to £500M for the most extensive.
In common with all major undertakings, the final solution cannot be delivered instantly and, depending on the form and scale, could take 5 to 10 years to complete. That is why it is vitally important to continue to manage and maintain the river and to have contingency plans should a flood occur before the protection is complete.
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5. Why wasn't this action taken earlier instead of leaving householders and businesses with major insurance problems?
While there has always been a risk of flooding from the River Clyde, research into Climate Change and Global Warming published in recent years now predicts increases in sea level and storminess not previously expected. This has had the effect of increasing what was a lower level of risk of flooding to a level, which must now be addressed.
This increased risk has caused the insurance industry to review their previous policy of providing universal flood insurance with the effect that it may not now be possible to obtain flood insurance for properties where the risk of flooding is too high. The City Council has addressed this change in policy by setting minimum levels of flooding risk in the City Plan for new developments.
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6. Wouldn't dredging solve the problem?
The effect of stopping dredging on flooding was studied in the 1980s before the harbour authority, Clydeport plc, stopped carrying out routine dredging above Shieldhall Quay. The studies showed that siltation of the river, even to a near natural condition, would produce only a very small increase in peak water level, in the order of 100mm.
This situation is unchanged, so, while dredging may have a marginal effect on reducing peak water levels, it would not be a solution on its own.
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7. Shouldn't the Council ban new development along the Clyde and in flood risk areas?
Current planning guidelines allow development in flood risk areas if a suitable level of protection is provided to reduce the risk to an acceptable level, and if the protection solution does not increase the risk of flooding to areas both up and downstream of the development.
By ensuring compliance with these guidelines, the City Council can permit and encourage new development and continue the regeneration of the river.
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8. How will the Water Services Bill improve things, i.e. does it give enough power to Councils to carry out flood control measures?
The Water Environment and Water Services (Scotland) Bill will involve Councils in the preparation of River Basin Management Plans to ensure the maintenance of water quality and the water environment. It will not provide additional powers to Councils to carry out flood control measures but may limit the types of engineering works a Council or others can carry out in or adjacent to a river.
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9. Will the problems encountered in Shettleston in the summer of 2002 be taken into account in any future studies?
The City Council, Scottish Water and others have investigated the extreme rainfall event, which occurred in Shettleston in 2002. The outcomes of the investigations will be used as the basis of providing solutions capable of being transferred to other problem areas.
Dealing with extreme rainfall and the effects of river floods on drainage systems will form part of the solution to deal with the flood risk from the River Clyde.
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