Coping with extreme floods: warnings, impacts and response

Transcription

1 The Extremes of the Extremes: Extraordinary Floods (Proceedings of a symposium held al Reykjavik. Iceland. July 2000). lalispuw.no Coping with extreme floods: warnings, impacts and response EDMUND PENNING-ROWSELL & SUE TAPSELL Middlesex University Flood Hazard Research Centre, Queenswav, Enfield, Middlesex ENS 4SF, UK s: e.penning-rowsell@.indx,ac.uk: s.tapsell@mdx.ac.uk Abstract Coping with extreme floods involves reducing the damage that they cause and minimizing their other impacts. This in turn means that we need to understand, first, the impacts of flood warnings on flood damage and on the people and property thereby affected, so that we can manage the total forecasting, warning and response system so as to optimize its impact vis à vis its costs. Secondly, given that we cannot prevent floods and all of their impacts, we need to understand the continuing adverse effects that extreme floods can have on those affected so that we can plan our assistance for these flood victims and minimize the long-term effects. Key words flood warnings; impacts; health effects; social dimensions A KEY AIM: REDUCING THE DAMAGE CAUSED BY FLOODS The flood damage data published in 1977 by Penning-Rowsell & Chatterton (1977) and other data given by Parker et al. (1987) represent maximum potential flood damage for residential and other property, ignoring the damage-reducing effect of action taken following the receipt of flood warnings (see also Black & Evans, 1999). Research has continued on flood warnings and their effects over the last two decades, as summarized by Parker (1991), Parker & Handmer (1998) and Penning-Rowsell et al. (2000). Particularly important have been surveys of those to whom flood warnings have been issued, designed to determine the actions that they were able to take, the damage that was thereby averted, and the factors that affected this (including flood warning lead time, the availability of assistance with moving vulnerable household goods, etc). Over 1200 interviews have been undertaken. The following equation, pioneered by Colin Green (Green & Penning-Rowsell, 1989), has been developed and calibrated in this research (Parker, 1991): FDA = PFA-R-PRAPHRPHE where FDA is estimated actual flood damage avoided owing to the flood warnings, PFA is the potential flood damage avoided (property plus vehicle damages avoided), R is the reliability of the flood warning process (i.e. the proportion of the population at risk which is warned with sufficient lead time to take action), PRA is the proportion of residents available to respond to a warning, PHR is the proportion of residents able to respond to a warning, and PEE is the proportion of households who respond effectively.

2 380 Edmund Penning-Rowsell & Sue Tapsell An important assumption in the 1977 research (Penning-Rowsell & Chatterton, 1977) was an aggregate response rate to warnings of 70% (a combination of PRA, PHR and PHE), and subsequent research was designed to refine that estimate. Parker (1991) reports conclusions of 0.55, 0.75 and 0.70 for these three factors, respectively, leading to a combined value of 0.29 to compare with the value of 0.70 published in The research over the last two decades therefore has yielded an aggregate response rate of less than 30% rather than 70%. The conclusion to be drawn from this is that benefit-cost project appraisals for flood alleviation schemes should use the moderated flood damage values arising from this research, rather than the maximum potential damage data as given by our FLAIR data archive (N'Jai et al, 1990). This is even more important given that our most recent assessment of R is 0.45 (both residential and commercial) such that only 45% of the population at risk is warned with sufficient lead-time to take action in order to produce damage savings (Parker & Tunstall, 1991; Parker, 1998). This means that FDA is approximately 0.13, so the estimated actual flood damage avoided owing to the flood warning is approximately 13% of potential damage (cf. c. 20% recorded by Smith, 1998). Flood warnings, for a variety of reasons, do not therefore yield the level of tangible damage saving at first estimated, so that while their benefits can still be considerable (and perhaps mainly intangible Green & Penning-Rowsell, 1989), these only begin to be realized when the total forecasting, warning and response system is operating effectively. Usually this is not the case (Penning-Rowsell et al, 2000; Parker & Handmer, 1998). IMPACTS ON VULNERABLE COMMUNITIES: EXTREME UK 1998 FLOODS Serious flooding affected the English Midlands at the Easter weekend in 1998, causing severe damage and the loss of five lives (which is rare in floods in the UK). In many areas the return period of the event exceeded 100 years, and in many locations the flooding occurred where there was little history of serious floods in the past (e.g. Kiddlington, Banbury, Northampton, Stratford-on-Avon) (Tapsell et al, 1999). The social research: the first phase We investigated the possible adverse health effects of this flooding as part of a number of Environment Agency initiatives designed to ensure that the lessons to be learnt from these flood events were properly recorded. Rather than conducting a sample questionnaire survey of all those affected, as in the past (Penning-Rowsell et al., 2000), we used a focus group approach so as to gather detailed information on the full impacts of the floods from a small group of those who had been flooded. This approach also allowed us to explore these impacts with a number of groups who are known to be the most vulnerable to the effects of flooding (e.g. the elderly; women; immigrants; those previously ill or infirm, etc). The results from the first phase of the research are in Tables 1 and 2. What they show, first, is that the impacts of the floods on the people affected was perceived to be considerably worsened and the stress of the event itself was much greater owing to

3 Coping with extreme floods: warnings, impacts and response 381 the lack of warnings given, especially since the rate of rise of the flood waters was high. The fact that the flood occurred in the middle of the night also meant that many of the arrangements common in flood plain areas for informal warnings based on observing rainfall rates and rivers rising did not operate (Parker & Handmer, 1998). There was, too, a considerable loss of confidence in the authorities responsible for river and water management, and also a loss of memorabilia and associated stress due to the lack of warnings, both of which served to undermine the residents' sense of security in their homes. Secondly, the perceived lack of response to the floods by the many agencies concerned not helped by the fact that it was a public holiday weekend made a Table 1 The stress felt by flood victims in the 1998 UK floods. Examples of factors that exacerbated stress The rarity of the event (residents were unaware of the flood risk). There was "no warning". The timing: the flood was "in the middle of the night". The sudden onset: rapid rise of water, perceived as not being a "natural" phenomenon. The depth and coldness of the flooding ( m). The contaminated water (and associated health fears). The flood occurred at the Easter holiday time (difficult to get advice and help; but some residents were away from home and thereby avoided the stress). Examples of factors that made the flood event and recovery less stressful The short flood duration (a day, rather than weeks). Low flood water velocities. Table 2 The impacts of the floods on the women affected. The extra burdens on women They are likely to spend more time in the flooded house than men. They have the major responsibilities for domestic tasks and therefore suffer more when these are disrupted; this is exacerbated when they work full or part-time. Children's routines and care disrupted, influencing women more than men. They usually have the major responsibility for nursing and health care (e.g. of the elderly) and these tasks are more difficult after a flood. They took on more of the responsibility for clear-up, insurance, builders, etc. They may have more emotional investment in the home as chief "homemaker" and suffer more severely when this is disrupted. The impact on Asian women in the community: negative factors Poor command of English exacerbated communication problems. Lack of knowledge of "how the system works" (new to country). Not able to go out unchaperoned to organize recovery, etc. Flooding not expected in a technologically advanced country. Young children and large families in small houses made recovery more stressful. Husbands doing night work (at the time of the flood). Some pre-existing ill health. Women confined to the home made organization and assistance with recovery more difficult; also "no escape" from the effects of the flood. Low income; probably less insurance. The impact on Asian women in the community: positive factors Family nearby, for staying and help with clear-up. Close supportive community of women to provide emotional support and assistance with children.

4 382 Edmund Penning-Rowsell & Sue Tapsell difficult situation worse, and again this can be traced in part (and sometimes in the main) to the lack of warning and notice of the occurrence and the severity of the event. Thirdly, communication difficulties made the warning and response arrangements such as they were inefficient or ineffective, not least among the Asian community represented by one of the focus groups (Table 2). This interesting and important result should also be seen in the context of the extra impacts that the floods had upon the women affected; Asian women suffered particularly owing to their special circumstances. This serves to re-emphasize that particular groups need special help during flood events, as well as the information on which to base the responses that they can make by themselves. These results indicate that the inadequate warning led to the perceived impacts from this serious flood being considerably exacerbated. It meant that the damage was greater than might otherwise have been the case, but the "psychological" or stress factors were even more magnified, not least because of the sparse experience of those affected with flooding in the past. The social research: the second phase A second phase of the research evaluated the situation approximately 19 months after the event and 12 months after the first interviews. Out of the 41 people in the original focus groups, 31 attended the second focus groups and the remainder were interviewed by telephone (Tapsell, 2000). The results here indicated that the majority of victims no longer perceived themselves to be suffering from any physical health problems which they could attribute to the flooding. However a minority (5 out of 41) were still experiencing persistent health problems, which they did attribute to the flooding. These included skin irritation, high blood pressure, and respiratory problems (from living in the damp houses). One respondent who had not reported physical health deterioration in the first interviews now reported being on medication for anxiety. The majority of flood victims still perceived themselves to be suffering psychological effects related to the flooding. This comprised continuing anxiety during heavy rainfall, and on-going fear of future flooding. A number of people had moved out of the area to escape the flood threat and, in general, people were still experiencing significant levels of stress associated with these anxieties despite the fact that the flood had a very long return period (probably 150 years) and more than 18 months had elapsed since the flood waters had receded. What this research shows is that the impacts of floods continue longer than we had previously believed; the decay effect was relatively slow. CONCLUSIONS Our research on the socio-economic effects of extreme floods in the UK shows that warning systems are poor at preventing flood damage (measured in terms of GB pounds or US dollars), and that the non-monetary impacts of floods continue much longer after the event than we had hitherto believed. In terms of the policy response of

5 Coping with extreme floods: warnings, impacts and response 383 those with authority in this field, this non-monetary impact phenomenon means that they should continue to have contact with those affected by flooding many months after the event, whereas this is very rare or non-existent in most floods in the UK (Parker & Handmer, 1998). The flood warning research shows that much needs to be done to make flood warning systems more effective and cost-effective, and that this cannot be done without considering the whole of the forecasting-warning-responsefeedback system. This system must be designed as a single entity rather than be the subject of fragmented responsibilities. More information on the research of the Flood Hazard Research Centre is at: Acknowledgements Contributions from Colin Green, Dennis Parker and Sylvia Tunstall are gratefully acknowledged. REFERENCES Black, A. & Evans, S. (1999) Flood Damage in ihe UK: New Insights for the insurance Industry. Department of Geography, University of Dundee, Dundee. Green, C. H. & Penning-Rowseli, E. C. (1989) Flooding and Ihe quantification of "intangibles"../. Inst. Wat. Environ. 3(1), Manage. N'Jai, A. N., Tapsell, S. M., Taylor, D., Thompson, P. M., Witts, R. C, Parker, D. J. & Penning-Rowsell, E. C. (1990) Flood Loss Assessment Information Report (FLAIR). Middlesex University Flood Hazard Research Centre, London. Parker, D..1. (1991) The Damage Reducing Effects of Flood Warning. Middlesex University Flood Hazard Research Centre, London. Parker, D. J. (1998) Review of Flood Warning Public Opinion Surveys Report to the Environment Agency. Middlesex University Flood Hazard Research Centre, London. Parker, D..1. & Tunstall, S. M. (1991) Managing Hood warning systems: the United Kingdom experience. In: Inspiration: Come to ihe Headwater (Proc. 15th Annual Conf. of the Assoc. of Floodplain Managers, Denver, Colorado), University of Colorado, Boulder, Colorado, USA. Parker, D..1. & Handmer,.1. W. (1998) The role of unofficial Hood warning systems. J. Contingencies and Crisis Manage. 6( I ), Parker, D..1., Green, C & Thompson, P. M. (1987) Urban Flood Protection Benefits: A Project Appraisal Guide. Gower Technical Press, Aldershot, UK. Penning-Rowsell, E. C. & Chatterton,.1. B. (1977) 77?e Benefits of Flood Alleviation: A Manual of Assessment Techniques. Saxon House, Aldershot, UK. Penning-Rowsell, E. C, Tunstall, S. M., Tapsell, S. M. & Parker, D..1. (2000) Ihe benefits of Hood warnings: real but elusive, and politically significant../ Inst. Wal. Environ. Manage. 14, Smith, D. 1.(1998) Water in Australia: Resources and Management. Oxford University Press, Oxford. Tapsell, S. M. (2000) Interim report on the follow-up study of the health effects of the 1998 Easter Hoods in Banbury and Kiddlington. Middlesex University Flood Hazard Research Centre, London. Tapsell, S. M., Tunslall, S. M., Penning-Rowsell, E. C. & Handmer,.1. W. ( 1999) The Health Effects of Ihe 1998 Easier in Banbury and Kiddlington. Middlesex University Flood Hazard Research Centre, London. Floods