Abstract:This paper considers probl

Abstract:
This paper considers problems associated with the artificial flooding of floodplain forests in an industrial region in central Germany. During the past eight centuries river regulation has reduced flooding to an extent dependent on local conditions. The lack of flooding has caused a new pedo-hydrological regime. Typical tree mixtures in the floodplain forests of oak, ash, elm and maple have changed over the last 120 years so that ash and maple now dominate. Sediments of the rivers Weibe Elster and Mulde were found to be contaminated by industrial pollutants, especially with heavy metals such as Cd, Zn, Co and Cr. Atmospheric pollution and the deposition of dust and gas contaminated by heavy metals over the last 100 years have been responsible for serious soil contamination. There is a danger of the migration of these heavy metals through the floodplain sediments and soils into groundwater. Artificial flooding is one method of re-introducing natural conditions to floodplains and their forests. Our investigations of the migration behaviour of contaminants, using sequential leaching procedures, have demonstrated that a high proportion of the stored heavy metals in the meadow loams is soluble and highly mobile. The release of heavy metals in the soils depends on the pH-value and grain size of the soils as well as precipitation and climatic conditions. The mobility of the heavy metals increases with rising acidification of the soils. Despite decreasing atmospheric deposition in the region of Bitterfeld and reduced deposition of basic flue ashes after the year 1990, increased mobilization of metals in the flood loams is likely to take place. The migration of these chemicals to groundwater is likely to be increased by water infiltrating from artificial flooding. Artificial flooding may therefore have previously unforeseen negative consequences.