Agriculture

Integrated management concepts for dry basins and polders for use as flood barriers – sub-project 2: adapted land use

The project researches the ecological consequences of agricultural use of flood basins. Research focuses on the feed, accumulation and release of heavy metals from retention area soils. The research also takes into account the effects of various types of agricultural use in river catchment areas on heavy-metal contamination. 

 

Summary

Flood basins are effective components of flood risk management. Between flooding events, the basins are dry (dry basins) and can be used for other purposes. However, agricultural use in particular conflicts heavily with the basins' flood protection function as, on the one hand, flood overflow reduces harvest yield and, on the other, flooding can transport pollutants into the retention areas' soils. These pollutants accumulate and can, upon subsequent flooding, be released once more. The research project aimed to record current land use and soil distribution in the examined Erft and Rems catchment areas and to minimise the negative ecological impact of retention area overflow during flooding. To this end, the effects of pollutant feed (particularly heavy metals) to flood basins on pollutant release, transportation and assimilation by crops were examined. Here, a distinction was made between short-term effects through changes to physical-chemical conditions (redox potential, pH value, heavy metal portability) through flood retention and long-term effects (pollutant accumulation through sediment and pollutant feed to soils).

Results:

  • Short-term changes to redox potential are of lesser interest in terms of agricultural use than long-term accumulation of heavy metals; the flood retention periods of only a few days are too short to trigger the pollutant release verified by laboratory tests.
  • The heavy metal contamination of the flood basins Winterbach (Rems) and Horchheim (Erft) differs substantially due to their different utilisation; due to mining activities, wind and water erosion, heavy metals are fed to the water bodies in the upper Erft catchment area, where these pollutants accumulate in the sediment.
  • The heavy metal contamination in Horchheim partially exceeds the BBodSchV (federal soil protection ordinance) limit values and does not permit the planting of food crops. Use as grassland or as fields for planting of energy crops is possible.
  • A good option for influencing sediment and heavy metal deposition is offered by basin drainage control: basins that are not used for agricultural purposes can serve as pollutant sinks in order to protect downstream riparians. These basins would then, however, require decontamination as for heavy metal contaminated brownfields.

More Project Informations

Project title:  Verbundvorhaben: Entwicklung eines integrativen Bewirtschaftungskonzeptes für Trockenbecken und Polder zur Hochwasserrückhaltung, Teilprojekt 2: Angepasste Landnutzung in Retentionsräumen und in deren Einzugsgebiet zur Minimierung von Umweltschäden und Ertragseinbußen in der Landwirtschaft

Project number:  02WH0656

Project period:  2005 - 2008

Project region:  Germany (Baden-Württemberg)

Project contact:

Frau Kreschnak

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Source: German National Library of Science and Technology Hannover (TIB)