Table of contents
- Draft key messages
- Executive summary
- 1 Introduction - 1.1 Scope of theme: Why care about floodplains?
- 1 Introduction - 1.2 The catchment-river-floodplain ecosystem and policies
- 2 Floodplains under pressure - 2.1 Floodplain characteristics and extent
- 2 Floodplains under pressure - 2.2 Current floodplain status in Europe
- 2 Floodplains under pressure 2.3 - Climate change and altered flood risk
- 2 Floodplains under pressure - 2.4 Hydromorphological pressures and alterations
- 2 Floodplains under pressure - 2.5 Pollution pressures
- 3 Improving ecosystem services and measures - 3.1 Ecosystem services
- 3 Improving ecosystem services and measures - 3.2 Measures
- 3 Improving ecosystem services and measures - 3.3 Examples of river and floodplain restoration
- 4 Managing from an ecosystem perspective
- 5 Conclusions and Outlook
- References
- Annex 1 European and Global Policy Context
- Annex 2 Definitions
- Annex 3 Ecosystem service overview
- Annex 4 Measures that improve services
2 Floodplains under pressure - 2.5 Pollution pressures
Although the Water Framework Directive and the Nitrates Directive in combination require reduction of nutrients and hazardous substances, those substances are still used. Floodplains commonly act as long term storage for water and sediments including those less desirable and hazardous substances. Nutrients and hazardous substances reaches floodplains from either the landside, from the river during floods, or from the atmosphere. Agricultural plant production uses nutrients and pesticides to promote plant growth. Often more nutrients are applied than taken up by plants, and unused nutrients are moved into streams either via groundwater (nitrates), or as attached to soil particles and moved with surface run-off (phosphorus). Those nutrients may cause eutrophication impacts on the floodplain but may also buffer against eutrophication impacts in the river. Active floodplains where vegetation is more prominent cycle nutrients into plants, and if soils are water logged, enable denitrification to take place. In the absence of an active floodplain, nutrients enters the river with less transformations and may cause eutrophication related impact on ecological status of rivers, lakes, transitional, and coastal waters.
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- “Nutriens and hazardous substances should be reach, not reaches “
During floods, sediments which may carry both nutrient and hazardous substance pollution are deposited on the floodplains, removing the polluting substances from the river, but in return polluting the floodplain. Especially in areas where mining and heavy industry were or still are important, heavy metal pollution of floodplains can be prominent, and may continue for decades after mining has been stopped (Ciszewski and Grygar, 2016). Examples of this can be found from most countries in Europe. Contaminated sediments are also of concern when performing river restoration as removing structural flood protection, weirs or dams. It has been found that contaminated sediments are often stored behind these structures, and may be released if structures are changed (Hahn et al., 2018). Atmospheric deposition of nutrients and mercury is a ubiquitous pressure, hence also occurs in floodplains (EEA, 2018b). Climate change induced increased temperatures is expected to alter the mobilization of chemicals in floodplains, but unfortunately, not much is known about environmental effects.
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generally there are point and not-point sources of pollution. Point sources are largely missing (mainly industry, heat by power plants, waste water from setllements etc)
flooding especially "catastrophic flooding" usually implies higher risk of pollution of water bodies and flood plains by e.g. oil from heating facilities, flooding industrial areas etc.
Propose to elaborate this with a few more sentences
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another reference to mining sediment mobilsation in floodplains https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/291646/scho1108bozd-e-e.pdf
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Also refer to remobilisation of historic mine-contaminated sediments from the floodplain into the river with potential for redeposition elsewhere with impact on human health or agricultural land. Directly linked to cattle deaths in Wales in 2012. https://www.sciencedirect.com/science/article/pii/S004896971301560X
The last sentence 'Active floodplains where vegetation is more prominent cycle nutrients into plants, and if soils are water logged, enable denitrification to take place. In the absence of an active floodplain, nutrients enters the river with less transformations and may cause eutrophication related impact on ecological status of rivers, lakes, transitional, and coastal waters.' is not really clear, especially the use of the term active floodplain. Should be described more precise.