Retain floodwater

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General description

Large flood retention area at the river March in Austria (source : BOKU, S.Muhar)

Studies on natural floods underline the importance of these events for riverine ecosystems and support the use of flood restoration in regulated rivers (Roni et al. 2005). Along the rivers, forests and marshlands have become established in areas that were formerly scoured by floods. Different measures targeted at floodplains can result in runoff control and appropriate land management (af-/reforestation, limitation of the intensive use of the floodplain, the reconnection or creation of by-pass channels and oxbow lakes, the reduction of the amount of impervious areas, the minimization of soil compaction and the protection, restoration and creation of wetlands etc.) and will contribute to control runoff. Beside providing extensively used areas (floodplain forest, wetlands) for controlled flooding, infiltration or detention basins are designed to hold runoff from impervious surface, allow the settling of sediments and associated pollutants and water to infiltrate into underlying soils and groundwater.


By restoring the floodplain and allowing the stream to flood under controlled conditions, the risk of flooding damages can be reduced. Buffer zones and storage infrastructures slow the water transfer time between the floodplain and the river, thereby spreading the flow and thus decreasing the flood intensity. Land use conversion from impervious surfaces or intensively used agricultural land to forest and wetland, especially with native vegetation, improves soil infiltration and retention capacity. Floodplain restoration measures should always be accompanied by management measures at the catchment scale. At a small scale, retention ponds or pools can be designed to provide additional storage capacity to attenuate surface runoff during rainfall events. Infiltration basins should not be used as solutions for larger drainage areas due to the increased risk of sediment loading to the basin, reducing its effectiveness as an infiltration feature and increasing the risks of pollutant loading that may be transferred to groundwater through infiltration (CIRIA 2009).

Expected effect of measure on (including literature citations)

The studies on natural floods and initial studies from restoration of flood flows suggest positive benefits for sediment transport, riparian vegetation, and aquatic biota (Roni et al. 2005). By promoting natural functioning of the aquatic ecosystem and of immediate and remote environments, floodplain restoration measures will have a positive impact on water quality, vegetation population, temperatures and habitat conditions. This will naturally be followed by a recovery of the aquatic ecosystem, and thus an increase in fish populations, a greater biodiversity and a higher natural biomass production (Roni et al. 2005). Changes in land use (increase of forest and wetlands areas) and slower runoff can lead to higher discharges of water into the ground. The amount of groundwater recharge also depends on local conditions, such as geology, legacy sediment that could be impervious and the hydrological condition of the aquifer (Habersack et al. 2008).

Category Description Source (citation)
HYMO Creation of sandbar habitats and inundated patches of woody vegetation Stevens et al. 2001
Vegetation Survival and growth of seedlings of riparian plant species is higher in areas with natural flood regime Johansson and Nilsson 2002
Fish Recovery of stagnophilic fish species Rood et al. 2003

Temporal and spatial response

Not available.

Pressures that can be addressed by this measure


Not available.

Case studies where this measure has been applied

Useful references

  • CIRIA (2009). Overview of sustainable drainage performance: information provided to Defra and the EA
  • Habersack, H., C. Hauer, B. Schober, E. Dister, I. Quick, O. Harms, M. Döpke, M. Wintz, and E. Piquette (2008). Risk Assessment and Risk Management: Effectiveness and Efficiency of Non-structural Flood Risk Management Measures. Flood risk reduction by PReserving and restOring river Floodplains (PRO_Floodplain). ERA-NET CRUE Funding Initiative on Flood Risk Management Research, Report I-3.
  • Johansson, M. E., and C. Nilsson (2002). Responses of riparian plants to flooding in free-flowing and regulated boreal rivers: an experimental study. Journal of Applied Ecology, 39, 971–986.
  • Rood, S. B., C. R. Gourley, E. M. Ammon, L. G. Heki, J. R. Klotz, M. L. Morrison, D. Mosley, G. G. Scoppettone, S. Swanson, and P. L. *Wagner (2003). Flows for floodplain forests: a successful riparian restoration. BioScience, 53, 647–656.
  • Roni, P., K. Hanson, T. Beechie, G. Pess, M. Pollock, and D. M. Bartley (2005). Habitat rehabilitation for inland fisheries. Global review of effectiveness and guidance for rehabilitation of freshwater ecosystems. FAO Fisheries Technical Paper, 484.
  • Stevens, L. E., T. J. Ayers, M. J. C. Kearsley, J. B. Bennett, R. A. Parnell, A. E. Springer, K. Christensen, V. J. Meretsky, A. M. Phillips III, J. Spence, M. K. Sogge, and D. L. Wegner (2001). Planned flooding and Colorado River riparian trade-offs downstream from Glen Canyon Dam, Arizona. Ecological Applications, 11, 701–710.

Other relevant information