merseymouth wrote:But if it is a known fact that an area of land is actually a historic flood plain (A) Why Build on it? (B) If you choose to Build on it why not make adequate dispersal measures? (C) Why not Elevate the properties as in days of old in the Fens? (D) The flat lands in Lancashire employ constant extraction pumping to keep areas dry, if pumping stations like that at Abbeystead work, why not use the system in such areas?
But even more importantly do folk actually buy houses in such areas? I ask this in much the same way as I would like to know why people buy houses on cliff edges subject to coastal erosion?
We live on a relatively small island, parts of which are densely populated, and demographic changes and culture (increasing numbers of homes in single occupancy and a preference for houses over flats) are such that it is probably impossible to meet demand and needs for new private and commercial properties without building in areas where there is a degree of increased flood risk.
pete75 wrote:Building on flood plains is sanctioned by the government as no development can legally happen without governmental permission unless it is of a very minor nature.
The Government in England and Wales has published guidelines for planning applications where there is a flood risk, which local authority planning committees must follow. In short they are something like this:
1. Don't build on land with a flood risk. There is usually insufficient flood risk free land available in the area to allow this, so
2. Default to only putting classes of buildings on flood plain which present a relatively low consequence if they are flooded, e.g. typically commercial premises, as opposed to private residences and more especially buildings with highly vulnerable occupants, e.g. nursing homes and hospitals, as well as important infrastructure like electricity stations etc.
3. Default to using flood plain that has the lowest level of increased risk, e.g. 1 in 200 instead of 1 in 75.
The developer's planning application will need to comply with the above guidelines and include a flood risk assessment of the impact of flooding and the mitigation measures and flood protection that it proposes to provide, e.g. things like raising the ground floor level.
Obviously the amount of potential land available that could be used for development that is flood risk free will vary between local authority areas. In some areas of the UK with likely low development pressures it's probably easy to fulfil development needs without using flood risk land, in others it's impossible.
The planning committee should block applications that don't meet the guidelines, but obviously the decision making process may be inappropriately influenced by local politics and politicians, and the Environment Agency therefore has a duty to review all such planning applications and advise the local authority. If the local authority overrules or ignores EA advice not to give planning permission, the EA can challenge the decision (can't remember if it goes to court or central government). However, EA resources are limited, and they are likely only to challenge where they are fairly confident of winning.
I can recall at least one developer's risk assessment for a major residential conversion on an exposed area of coastal flood risk which basically suggested that because residents would have X minutes to walk along a causeway to get to a place of safety, it was OK, i.e. the risk assessment was little more than suggesting the residents should be able to evacuate in time. It was a laughable risk assessment, and I'm pretty sure that one was turned down.
As for protection measures like raising flooors and dispersal methods, fenland drainage systems etc., all these things are done and used, but there is usually no single panacea. All these systems have weaknesses or potential failure modes, and usually it's necessary to consider multiple systems.
If you improve drainage in one area, you may find that the increased water flow through results in areas downstream becoming flooded. Similarly there can be synergistic effects: inland drainage systems and pumping stations to help remove the water from a period of heavy rainfall can be rendered almost useless if the same low pressure weather system has also resulted in a major storm surge, i.e. the sea/tidal river levels can be so high that outfalls from the inland drainage are submerged, with the result that water backs up inland.
In fact there are several types of flooding. It's not just a matter of the risk of rivers overflowing or coastal storm surges. Drainage and sewage systems can be overwhelmed by heavy rainfall and/or blocked, and sometimes extremely heavy rainfall can flood areas before it even gets anywhere near the river or drainage systems (as happened in Hull in 2007). Moreover, as I mentioned above, often these types of flooding occur together, making the impact worse, harder to predict/model, and harder to mitigate and protect against.
merseymouth wrote:Living in an elevated area myself , for us to suffer flooding of the type seen the Liver Birds would have to be up to their necks in water, yet I have to pay for "Flood Protection" in my home insurance.
I presume you mean that your cover includes flooding as standard together with all the usual covers in a household policy, e.g. fire, explosion, storm, escape of water, impact by vehicles etc. If you are in a low/normal flood risk area, then your premium will reflect that, and the percentage of the premium that might be notionally allocated to the flood risk is tiny. It's not worth it to insurers to start offering policies where people can choose to omit flood cover, or impact cover etc. because they reckon the risk is negligible. The discount would be trivial and the administration costs would exceed the discount. Bear in mind also that while it might be impossible for sea levels to reach your home, sewer system back up or heavy rainfall and surface run off are things which you might still suffer, so it's worth having the cover even if you think you'll never need it.