Floods have affected human lives since the beginning of civilization
Floods have affected human lives since the beginning of civilization. But all types of floods - riverine and coastal floods and storms, sudden snow melts, floods after intense rainfall - have become more destructive in recent decades, because increasingly human infrastructure is being built in flood-prone areas, and they are likely to be even more pronounced in the future.
The direct and immediate impacts on human health include loss of life, injuries and, the lack of clean water and destruction of sewage systems. These cause another set of threats to human health - diarrhoea, cholera and other life-threatening, water-related ailments.
Receding floods in some countries also provide the perfect environment for malaria-carrying mosquitoes.
Finally, there are the longer term effects on mental health, such as anxiety and depression that often follow a major flooding event.
While we cannot easily prevent major floods, we can ensure that we benefit from the flood protection services that wetlands supply free of charge.
Rivers, lakes and marshes slow down and retain floodwaters. But they cannot do this if we build on natural floodplains and concrete our rivers banks and drain our marshes.
It is important to recognise that flooding is a natural phenomenon that is vital for maintaining the ecological function of wetlands.
Many millions of people depend on the natural inundation of wetlands, especially those whose livelihoods depend on floodplains for flood-recession agriculture and fish production.
Opportunities are being examined along many of the UK's rivers to remove 'hard' engineered flood defences and to create 'washlands' which can temporarily store flood waters and attenuate flooding.
WWT in action
WWT has installed wetland systems which slow the release of heavy rainfall at several of its centres in an attempt to reduce flooding.
WWT Consulting has created multi-functional wetlands which store flood waters and release these back at a controlled and regulated rate.
WWT Consulting designed one of the first urban stormwater wetland systems designed to provide additional storage of urban stormwater as well as providing high quality wetland habitat.
Key facts
- Following the autumn 2000 floods, a review indicated that washlands along the River Aire provided up to 25Mm3 of storage and represented an essential element in the provision of flood protection in the catchment. Without these washlands the review indicated there would have been extensive flooding through Leeds with potential damages of £10's millions.
- The restoration of the River Quaggy in South London, and its associated floodplain, has reduced the flood risk fro 600 homes and businesses and increased the standard of flood protection from 1 in 5 years to 1 in 70 years.
- Wetlands can significantly mitigate the impacts of storm surges and coastal flooding. The Gulf Coast of the USA experienced crippling damage as a result of wind, tidal surge, and flood related impacts during the 2005 hurricane season. Experts have concluded that the significant historic losses of wetlands in southern Louisiana contributed to the magnitude of hurricane impacts.
- A study in the USA concluded that restoring wetlands along the 100 year flood plain of the Upper Mississippi River could increase water storage capacity to a similar volume to the Mississippi Flood of 1993 that caused US$16 billion in damages.
- A recent study in the USA estimated that 0.4 hectares of wetland can store over 6,000 cubic metres of floodwater.