Climate change

Flooding in Europe: health risks

Flooding is one of the most widespread of climatic hazards and poses multiple risks to human health, yet there has been little systematic research work on health outcomes and the means by which vulnerable populations and health systems respond to those risks. Given the prospect that flood hazards may increase as a result of climate change, it is timely to make a strategic assessment of the existing knowledge base on health and flood risk (Tyndall Centre for Climate Change Research, 2004).

Flood events can take many forms, including slow-onset riverine floods, rapid-onset (flash) floods, accumulation of rainwater in poorly-drained environments, and coastal floods caused by tidal and wave extremes. Both inland and coastal flooding may be associated with windstorm events. Floods also vary greatly in scale and impact, according to depth, velocity of flow, area covered, content, speed of onset, duration and seasonality. A flood event that has severe consequences (variously defined) may be termed a flood disaster, and the human impact of flood disasters is concentrated disproportionately in developing countries. Though major limitations remain in our ability to make robust projections of future rates of climate change and its effects, increasing predictive evidence of heightened global risk of inland and coastal flooding is emerging. Over the next 100 years, flooding is likely to become more common or more intense in many areas, especially in low-lying coastal sites and in areas that currently experience high rainfall. Marginal changes in the geographical distribution of flooding are also possible. However, it is not feasible to predict the precise locations at increased risk of flooding due to climate change: part of the problem is that flood risk dynamics have multiple social, technical and environmental drivers.

See Floods, health and climate change: a strategic review - Tyndall Centre for Climate Change Research

Health effects of flood events

There is very limited quantitative evidence of the health impacts of floods. The European Centre for Disease Prevention and Control (ECDC) has undertaken a preliminary review of the adverse health effects of flood events.

Flood events are the most frequently occurring natural disasters worldwide, and may increase in the future as a result of climate change. A limited number of short term epidemiological studies have been conducted to assess the health impacts of flooding, but studies of long-term health and economic impacts are lacking.

Limited data on flood events shows that the greatest "burden of mortality" is from drowning, heart attacks, hypothermia, trauma and vehicle-related accidents. The speed of onset of floodwaters is a determining factor in the number of immediate flood-related deaths.

Adverse effects on human health include the following:
  • Trauma deaths, mainly by drowning. Drowning is the leading cause of death in case of flash floods and coastal floods. Fatal injuries can occur during evacuation or during cleanup activities.
  • Flood-related injuries, such as contusions, cuts and sprains have been reported in several studies, as have burns, electrocutions, snake bites and wound infections. However, the number of serious injuries observed after violent flooding events generally turns out to be much lower than initial estimates predict.
  • Enteric infections due to the disruption of sewage disposal and safe drinking water infrastructure.
  • Increases in mental health problems such as anxiety, depression, sleeplessness, and post-traumatic stress disorder among flood victims. The risk estimates for physical illness in adults declined after adjustment for psychological distress, while psychological distress remained strongly associated with flooding after adjustment for physical illnesses.
  • Vectorborne disease, such as malaria, dengue and dengue hemorrhagic fever, yellow fever, West Nile fever and rodent-borne disease, such as leptospirosis. There is some evidence that diarrhoeal disease increases after flooding, particularly in developing countries but also in Europe. Standing water caused by heavy rainfall or overflow of rivers can act as breeding sites for mosquitoes, and therefore increase potential exposure to infections such as dengue, malaria and West Nile fever among people affected by the disaster and among emergency workers. West Nile fever has emerged in Europe after heavy rains and flooding, with outbreaks in Romania in 1996-97, the Czech Republic in 1997 and Italy in 1998.
  • There is also an increased risk of infection from diseases contracted through direct contact with polluted waters, such as wound infections, dermatitis, conjunctivitis, and ear, nose and throat infections.
  • Contamination by toxic chemicals during floods is theoretically possible but no verifiable correlation has been observed or measured so far.
  • Other negative health outcomes, for example related to the disruption of healthcare services and population displacement.

See Global Health Impacts of Floods: Epidemiologic Evidence
See What are the human health consequences of flooding and the strategies to reduce them? - WHO
See Flooding and communicable diseases fact sheet - WHO

See WHO Rapid Health Assessment of Flooding in Bulgaria, 2005, which covers the main public health issues that should be considered during and after a flood and is one of the most consistent documents assessing the current situation and providing recommendations for local response to flooding.

The European Flood Alert System

Between 1998 and 2004, Europe suffered over 100 major damaging floods, including the catastrophic floods along the Danube and Elbe rivers in summer 2002. Severe floods in 2005 and 2007 further reinforced the need for concerted action. Since 1998 floods in Europe have caused some 700 deaths, the displacement of about half a million people and at least €25 billion in insured economic losses.

Directive 2007/60/EC on the assessment and management of flood risks entered into force on 26 November, 2007. This Directive now requires Member States to assess if all water courses and coast lines that are at risk from flooding, to map the flood extent and assets and humans at risk in these areas and to take adequate and coordinated measures to reduce this flood risk.

Since the beginning of 2003 the European Commission DG Joint Research Centre (JRC) is developing a prototype of European Flood Alert System (EFAS) in close collaboration with relevant institutions in the Member States. The JRC benefits from experience gained already during the European Flood Forecasting System (EFFS) project financed by the EU DG Research.

The European Flood Alert System (EFAS) is a research project that aims at improving preparedness for oncoming flood events by:

• informing the authorities in the Member States of the possibility of a flood before the local systems capture the event with their own monitoring and forecasting systems;
• providing catchment based information that gives downstream authorities an overview of the current and forecasted flood situation also in upstream countries.

This does not only include the immediate upstream country but also any further potentially useful upstream information. EFAS provides medium-term (3 to 10 days) flood forecasts, based on different meteorological inputs, as complementary information to the typical short-term (less than 48 hours) forecasts performed by national centres. The challenge of EFAS is to combine all hydrographs, calculated from different medium-range weather forecasts, into one early flood warning information that is useful for local flood forecasting centres. EFAS forecasts are supposed to be used as a pre-alert to allow the receiving authorities to be aware of the possibility of a flood taking place. In other words, with EFAS forecasts in hand, local forecasters can already play through a number of different “what if” scenarios and, as the event approaches and its location and magnitude become more certain, national authorities can act more quickly and accurately, increasing the economic value of their forecasts.

The EU Project (FLOODSite: Integrated Flood Risk Analysis and Management Methodologies) aims to deliver: (i) an integrated, European, methodology for flood risk analysis and management; (ii) consistency of approach to the causes, control and impacts of flooding from rivers, estuaries and the sea; (iii) techniques and knowledge to support integrated flood risk management; (iv) sustainable “pre-flood” measures (spatial planning, flood defence infrastructure and measures to reduce vulnerability); (v) flood event management (early warning, evacuation and emergency response); (vi) post-event activities (review and regeneration); (vii) dissemination of this knowledge and networking and integration with other EC national and international research.

See Directive 2007/60/EC on the assessment and management of flood risks
See European Flood Alert System - European Commission
See Integrated Flood Risk Analysis and Management Methodologies
See European Flood Forecasting System (EFFS) project
See The benefit of probabilistic flood forecasting on European scale - Results of the European Flood Alert System for 2005/2006, Joint Research Centre, European Commission

Technical preparedness and response to flood crisis:

See Technical Guidelines - Emergency Management Essentials - WHO
See FLOODS - Technical Hazard Sheet - Natural Disaster Profile - WHO
See Emergency preparedness and response - WHO
See Flooding – Health Protection Agency, UK

 Mapping the flood events

The Dartmouth Flood Observatory detects, maps, and measures major flood events worldwide using satellite remote sensing. The record of such events is preserved as a "World Atlas of Flood Hazard". An Active Archive of Large Floods, 1985-2006, describes these events individually. Maps and images accompany many of the floods, and can be accessed by links in the yearly catalogues. As the archive of reliable data grows, it is increasingly possible to predict where and when major flooding will occur, and to analyse trends over time. "Surface Water Watch™" is a satellite-based surface water monitoring system. Orbital AMSR-E microwave measurements over selected river reaches are used to measure discharge and watershed runoff every two days. The system can be used to determine where flooding is under way, to predict inundation extents, and to assess the surface water status of seasonal wetlands.

See floods in Romania and Bulgaria - Lower Danube River - 2006
See floods in Czech Republic and Austria - 2006
See floods in Eastern Europe - Danube and Tisza Rivers and tributaries - 2006
See floods in Serbia, Croatia and Bosnia - Danube, Sava and Velika Morava Rivers - 2006

Mortality due to flood events

Deaths associated with flood disasters are reported in the EM-DAT disaster events database. The most readily identified flood deaths are those that occur acutely from drowning or trauma, such as being hit by objects in fast-flowing waters. The number of such deaths is determined by the characteristics of the flood, including its speed of onset, depth, and extent. Information on risk factors for flood-related death remains limited, but men appear more at risk than women. Those drowning in their own homes are largely the elderly.

See from EM-DAT disaster events database - flood victims in the EU 1990-2005
Although the risk of deaths is most obviously increased during the period of flooding, a controlled study of the 1969 floods in Bristol, United Kingdom, reported a 50% increase in all-cause deaths in the flooded population in the year after the flood, most pronounced among those aged 45-64 years.

Inconclusive evidence for diarrhoeal deaths has been reported from several studies of floods in low-income countries.

See Global Health Impacts of Floods: Epidemiologic Evidence

Deaths of European Union residents caused by the tsunami in south-east Asia in 2004

European Union residents (most of whom were holidaying in the region) fell victim to the tsunami that struck south-east Asia on 26 December 2004. Therefore, the tsunami has an impact on the statistics on causes of death at both European and Member State level, particularly for Sweden where the number of citizens killed in the tsunami was comparatively high. In the Member States, statistics on the causes of death are based on medical certificates which are completed by doctors for each death.

However some residents die in a country other than their country of residence and, in certain Member States, there is no procedure for collecting and inputting information on the cause of death in such cases. As a result, the death is registered in the statistics of the country in which this person lived as "cause unknown" (or may even not be registered at all in the statistics on causes of death). Although the effects of this type of under-coverage have relatively little influence on the overall statistical picture, they do become important and visible in the case of accidents and catastrophes involving a large number of victims, such as aircraft accidents. Furthermore, the number of residents dying abroad can increase in tandem with the increased mobility of European citizens. Given the scale of the catastrophe (the media reported thousands of victims from the EU), there was a possibility that seriously insufficient or erroneous coverage could have long-term effects on the comparability of European statistics on the causes of death.

See Deaths of European Union residents caused by the tsunami in south-east Asia in 2004 - Eurostat

EU studies impact and adaptation assessment for possible climate-related health outcomes in Europe

The cCASHh (Climate Change and Adaptation Strategies for Human Health in Europe) project is a European Union FP5-funded project, coordinated by the WHO Europe, with the aim of assessing and enhancing EU potential to adapt to climate-related effects on human health.

See EU projects to improve public health knowledge on extreme weather/heat waves: risks and responses