Appendices:
Appendix 1: The Insurance Template

(© Crichton, 1998)

The prime consideration in any proposed development must be possible risks to the health and safety of the public. Where rivers are "flashy", floodwaters can rise very quickly, and in hilly areas, the velocity of the floodwater can wash vehicles and buildings away, and cause fatalities. Sometimes, however, there may be compelling commercial, practical, and political reasons for siting certain types of development in a hazardous area. The author has therefore proposed three different categories of development. The precise definitions are obviously up to each planning authority, but the following "Insurance Template" has been used by a number of local authorities as a guide.

Category One - Strategic Sites

Facilities which must continue to function in times of flooding, for example, emergency services, hospitals, electricity supplies, telephone exchanges, mobile telephone and broadcasting transmitters, and emergency control centres.

Such developments should not be permitted in flood hazard areas unless very high standards of local defences can be guaranteed.

Category Two - Residential

Facilities where the public sector is prepared to provide a high standard of flood defences where necessary. The minimum level of protection which would enable insurers to offer cover at normal terms for residential properties is at least a 200 year return period up to the year 2050, after taking climate change into account.

The standards proposed by insurers are as follows;

Table 9 The Insurance Template
© Crichton, 1998

Climate Change

The climate change adjustment is very important, it should take into account that in general, the100 year return period flood now will, by 2050, become:

•  10 to 20 year for coastal flood (ignoring increasing wave heights)

•  60 to 65 year for fluvial flood

Source: Scottish Executive Central Research Unit Report, May 2001

A "100 year event" is really another way of saying a 1% probability of flooding every year. If there are 100 developments each with a 1% probability of flood, that means that every year, there is a probability that at least one of them will flood. Insurers have to spread these losses over time, and the shorter the timescale between floods, the higher the premiums will have to be. Where the probability of flood over the next 50 years is going to rise from 1% a year to 3% a year due to climate change means that it is almost inevitable that the building will flood at some time in those 50 years. As Section 27 of NPPG 7 points out, for the 100-year flood, there will be a 51% chance of at least one such event during the 70-year lifetime of a building.

The suggestion of a 500 year return period for bungalows and ground floor flats has caused some debate as to its reasonableness for a large development of mixed housing types. On the other hand, solutions should not be unduly costly. Few sites are completely flat, bungalows could be sited on raised ground and fitted with large skylights which can be opened for escape purposes in an emergency. If blocks of flats are being built in flood hazard areas, consider using the ground floor for parking, drying areas for clothes etc., rather than accommodation.

Sometimes individual houses have been built on "stilts" to reduce the flood vulnerability, but this is not always a good solution because owners are tempted to turn the area under the house into additional accommodation space.

Careful planning can do much, and local solutions might include:

•  Raising the height of the ground floor of the building (solum), and ensuring foundations are able to cope with flooding. (This will also depend on soil conditions; sandy soil and clay are generally very vulnerable to flood)

•  Designating lower lying areas of the development site as recreational areas

•  Following the guidance in the Sustainable Urban Drainage Manual

Developers may well be happy to accept such relatively low cost measures as an alternative to flood defences, especially if it avoids insurance problems for their customers. After all, without insurance, the customer cannot get a mortgage, and the property will remain unsold.

It should be remembered that if the land is raised to reduce flood impacts, this will remove flood storage and additional flood storage will be needed elsewhere to compensate.

Caravan Sites

Caravan and camping sites are an obvious potential problem in that the residents may not know the area and may be unaware of the flooding dangers. The owners of such sites need to be informed of the chances of flooding, the likely depth of flood, where the safe areas of the site are, and what sort of advance warning they might get. If there is a hazard, they should be advised to talk to the local authority and emergency services for advice on emergency procedures. The information on the flood risk, and what to do if a flood warning is given, should be provided to visitors on arrival or registration, and on clear fixed signs at the entrance to the site. Safe shelters should be clearly marked. This should be made a condition of the site licence if one is required.

There is a case for distinguishing between static residential caravans and seasonal touring caravans:

•  Touring caravans can be moved out of danger fairly quickly if a flood warning is given

•  Touring caravans tend not to be on such sites in the winter when the flood risk is greatest.

•  The value of property at risk tends to be much lower for touring caravans.

It is suggested therefore that for seasonal touring caravan sites, a lower standard of protection may be acceptable, provided this is kept under review each time the licence is renewed, and provided adequate warning and evacuation arrangements are in place. For mixed sites, the static caravans should be located in those areas of the site which are at the lowest risk from flood.

Try to avoid permitting touring caravan sites near rivers where there are bridges downstream; caravans can be swept away and become lodged under bridges, creating a dam, which can make flooding worse.

Category Three - Commercial and Industrial

Developments where the owners would be responsible for providing their own defences, or where the flood hazard is considered to be less important than other considerations, such as the need to be close to a river. Some developments in this category may need special treatment, however, for example:

Where the site will attract the public, especially young children and old people (such as health centres and leisure centres),

Where large numbers of the public are likely to gather, and where evacuation routes are limited,

Refuse tips or areas where hazardous materials are to be stored or processed,

Waste water and sewage treatment plant. (Sewage could escape onto adjoining land.)

Health and safety must always be the prime consideration. It should be remembered that flooding could often occur very quickly without warning, leaving little time for evacuation.

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