Saturday, July 14, 2012

Flooding and Development in the UK: Some thoughts on ASC Report

The recent ASC Report provides some interesting insights into current planning practices in the UK in relation to flooding. The ASC report (chapter 2) suggests that climate change is not the only factor increasing flood risk (page 27). It points out that risk changes if the probability of an event occurring changes OR if the consequences of an event alter. The first aspect is meant to cover the purely physical aspects of a hazard or rather of climate change in affecting flooding, whilst the second aspect is meant to relate to the socio-economic aspects of a hazard. It could be argued that a hazard isn’t really a hazard unless people are involved so an ‘event’ isn’t really a hazardous event unless there is a vulnerable population, so the two aspects may be more tricky to separate than appears. The two may go hand in hand.

Leaving this aside, the report does highlight the importance of the need for planning that bears these aspects in mind. The tables on pages 28 and 29 also provides some estimates of the amount of stock at risk from different types of flooding with 1.2 million properties at risk from river flooding, 230,000 of these at significant risk (a greater than 1 in 75 chance in any given year). The report points out that most floodplain development is within built-up areas that already have flood defences. Continuing development behind these existing defences increases the total value of assets that are being protected. In any cost-benefit analysis this increased value will make any future investment decisions easy – keep investing in defences as the value of assets keeps increasing. This means that current flood defences lock-in long-term investment, meaning that higher and stronger defences are continually required. The report recognises that this has been known for a while as the ‘escalator effect’.

The report also identifies that only a small number of planning applications have been approved when there was a sustained objection from the Environment Agency (EA). This implies that most planning applications meet the requirements of the EA for taking into account flood risk – a comforting point. However, the report also notes that, in general, local authorities are implementing national planning policy by continuing to build with protection in floodplains (page 36 of the report). In addition most flood risk management policies in plans focus on making development safe once the strategic decision to build in floodplains has been taken (page 37 of the report).

Combined this implies that floodplain development will continue and will produce an investment strategy for flood defences that encourages further development in already protected areas, forcing further and more extensive protection of these areas. The report states that the EA as taken a strategic approach to funding structural flood defences ‘targeting investment towards communities at greater flood risk and with the highest social vulnerability’ (page 40). The justification for this approach, however, is then expressed in terms of average cost-benefit ratio of 8:1, i.e. for every £1 spent on flood defences there is an expected reduction in long-term cost of flood damage of £8. This implies that social vulnerability is defined in terms of money as are any other benefits. This would suggest that assets that are relatively easy to attach a monetary value to will weigh heavily in these calculations. Again this would encourage development in flood protected areas as any additional value from the buildings an infrastructure will increase the cost-benefit ratio and so ensure the continuation of more, stronger and higher flood defences. Whilst here is nothing inherently wrong with this it does mean that if or when the defences are breached the cost of flood damage will be huge. How is this potentially high magnitude cost worked into the cost-benefit equations? Is the potential loss or cost discounted and over what time scale? How does the probability of such a high magnitude loss change as both aspects of flood risk mentioned above, the physical and the socio-economic, change into the future? Is the potential cost so huge that the defences must alwasy be enhanced into the future no matter what the rate of cliamte change or the cost? Is the current strategy commiting the future to locational inertia of housing, business and infrastructual investment?

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