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Last Updated: Tuesday, 10 January 2006, 03:44 GMT
Q&A: Can we avoid more flooding?
Flooding at Oulton Broad
High tides. Pic Matthew Norton
This year has seen severe flooding across areas of England and Wales after intense rains led to rivers bursting their banks.

Despite protests from local residents, the government has not ruled out more development on flood plains.

Professor Tom Coulthard of the Department of Geography at the University of Hull, is an expert on urban flooding. He answers some of your questions on future planning and floods.

I am a Local Councillor in Preston. For some time I have tried, unsuccessfully to raise the issue of flooding relating to poor drainage systems. Do you have any advice about how investigate the potential risk?
Jack Davenport, Preston City, Lancashire
There is an interesting split in responsibilities here, as gulleys at the edge of the road are the responsibility of the local council. However, the sewers that the gulleys drain into are the responsibility of the local water utility.

Your local water utility should have a DG5 register of properties/areas liable to flooding from sewers, and it may help to be registered on that. But people are reluctant to do this as it may blight houses when it comes to re-selling them.

Can we look at over-development of flood plains and underinvestment in flood defences - before we roll out the tired garbage about anthropogenic climate change again?
John B
Over-development on floodplains and underinvestment in flood defences are certainly important issues in their own right. By building on floodplains you can reduce natural storage capacity within rivers, and the removal of this capacity can lead to increased flooding downstream. This in turn can lead to the requirement for larger flood defences. However, flood defences themselves simply convey the water down the river, possibly increasing flood risk there. Rivers and flooding are part of a complex interlinked system, and it is important for planners, the EA and local Govt to work together to look at flooding in a river as a whole rather than just on one site.

However, the importance of climate change is that if climate change causes us to have wetter or more stormy weather; flooding could be much worse everywhere in the UK, whereas changes to development or flood defence will only have local impacts.

The problem is drainage. Most of rural flooding was caused by the drain and sewers not being able to take the amount of water, not the rivers bursting their banks. These are in the control of local authorities and water companies. The main problem is that they are not emptied or cleaned out regularly enough.
Carl Peter Mathie, Reading
Yes, maintenance is certainly an issue, and as mentioned above, the split responsibility can make them more difficult to manage. It is really important for the EA, Local Councils and the local water utility to work together to manage and plan drainage systems.

Why do people living in a flood plain go back year after to rebuild their homes?
Joan, USA
This is a hard question to answer, and I think there is no one answer. Often its for largely personal reasons as people like living near rivers - or because its home. Sometimes people have no choice, as property may be cheaper closer to the river because of the risk.

I read that the fields surrounding rivers should be planted with moisture absorbing plants to impede flow to the rivers. I have seen rainwater streaming down the bare soil left in fields after harvesting maize. Why is this planting not done? Are the rivers dredged still? They used to be.
David Walter, Hereford
Planting trees in the uplands that drain into rivers could slow down the transfer of water into rivers and thus reduce flood risk. Much of the UK (over 90%) used to be forested, and this has a far greater sponge like capacity to absorb water and then release it more slowly. By studying sedimentary records of how rivers have changed over the last 10 000 years, we can see evidence of flooding being reduced when forest levels were much higher.

Unfortunately, it's not as simple as planting trees everywhere to help stop flooding, as in doing so we lose agricultural land.

Some rivers are still dredged, but there are concerns for wildlife (for example spawning grounds for fish) and in some rivers dredging can stir up old sediment contaminated with heavy metals.

The River Yare. Pic - David Parker

If the government are giving carte-blanch to developers to build on flood plains, will they guarantee to cover the costs in the developments are flooded? If they did, I am sure it would stop these developments straight away.
Susie
The govt does not give carte blanche to developers. Since 2001, the planning laws are much stricter, and the EA have far more powers to object to developments. Some developments still get through without the EA's consent but it is quite unusual. However, sometimes permission is given and advice overruled because of the greater economic benefit to an area. But in general new planning consent on floodplains is very hard to obtain now.

A one in a 100 year flooding event - has this been reduced since knowledge of global warming and associated effects? What of new building policies? For example, building on flood plains and covering up swathes of land with concrete and tarmac creating crater run-off in heavy rains! Why aren't or local authorities making use of brown belt land and giving building consent toward multi-story developments to meet with the need for extra housing?
Tony Dale, Lowestoft
This is a very important point. The 1 in 100 year flood is only a probability of a flood, and this probability is calculated using history of floods in a river catchment. So if you have two 1 in 100 year events in 20 years, then the history of flooding changes considerably. This may lead to a 1 in 100 year flood being re-defined as only a 1 in 20! If done properly (as by the EA) then the calculation of the probability of a flood should be regularly re-calculated to incorporate the latest weather/climate data. Also many of these figures are only based on 20 or 30 years worth of data, and the 1 in 100 year event is extrapolated from this.

Multi storey development, with water resistant garages in the ground floor - that can be flooded is one idea that could allow for development on floodplains. I think we need to be creative and think more about living with flooding rather than just trying to stop it.

The use of intensive and extensive roofs (green roofs with plants, shrubs and grass) can help to control rainwater run off and attenuate surface water drainage. They have been shown to reduce the heat reflected from surfaces in cities by up to 10C (refer Manchester University), make the air fresher, help to combat global warming. And they are pleasant places to be. But the planning authorities are reluctant to pass them and builders don't want to build them. When is the UK going to really start combating global warming and flooding by installing more of these roofs?
Roofs may have an impact, and certainly the hard concrete urban materials are impermeable and make rain water run off into drainage systems and rivers far more rapidly. So thinking about how we design urban areas is important. This has been looked at through the governments SUDS (Sustainable Urban Drainage) program.

However, money rules in property development, so cheaper solutions tend to dominate. One way around this may be to alter planning laws, or probably more effectively building regulations to force people to use 'softer' construction methods. This has been a successful mechanism to improve the energy efficiency of new houses.

Given the government's continued support for building on flood plains, if insurance companies decline to provide cover for flooding will the government setup its own fund to insure homeowners?
Gary Sutherland, Carradale, Kintyre
This is an interesting point. The UK is nearly unique in western countries by not underwriting flood risk. Instead, there is a statement of principles between the insurers and the government, whereby the insurance companies say they will insure properties in flood risk areas as long as the govt protects them to a 1 in 75 year level, or is planning to do so in the next 5 years.

It is an interesting economic question as to whether the money is better spent on flood defence or underwriting possible flood damage! Or both! Someone somewhere has to pay and ultimately it is us, whether through the government (through taxes) or through insurance companies (through increased premiums).

A question about ditches. Is there any move to "green" the bodies in charge of digging drainage ditches - the Internal Drainage Boards ? At the moment they only seem to understand digging straight deep (and deeper) ditches and high (and higher) bunds. What about returning large sections of farmed wetland back to its original state so that there is a strong natural sponge along river courses?Most of it has only been drained for 50 or 60 years.
Andrew Cook, Norwich
This is an interesting issue. Many of the areas that flooded this summer in the NE of the UK (Lincolnshire and East Riding of Yorkshire) was formerly marshland that has been drained over the last 200 years and reclaimed as farmland. Much of this is important agricultural land and landowners would argue that the drains need to be cleared and maintained. However, there are also wildlife issues, as they are also home to many important species. Possibly one compromise is the creating of more green corridors by restoring some old land to its previous state, but maintaining other ditches? It is a difficult issue though and there is no simple answer.





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