Restoration strategies for river floodplains along large lowland rivers in Europe

Abstract

1. Most temperate rivers are heavily regulated and characterised by incised channels, aggradated floodplains and modified hydroperiods. As a consequence, former extensive aquatic /terrestrial transition zones lack most of their basic ecological functions. 2. Along large rivers in Europe and North America, various floodplain restoration or rehabilitation projects have been planned or realised in recent years. However, restoration ecology is still in its infancy and the literature pertinent to river restoration is rather fragmented. (Semi-) aquatic components of floodplains, including secondary channels, disconnected and temporary waters as well as marshes, have received little attention, despite their significant contribution to biological diversity. 3. Many rehabilitation projects were planned or realised without prior knowledge of their potential for success or failure, although, these projects greatly contributed to our present understanding of river-floodplain systems. 4. River rehabilitation benefits from a consideration of river ecosystem concepts in quantitative terms, comparison with reference conditions, historical or others, and the establishment of interdisciplinary partnerships. 5. We present examples from two large European rivers, the Danube and the Rhine, in which the role of aquatic connectivity has been extensively studied. The Danube delta with its diversity of floodplain lakes across an immense transversal gradient (up to 10 km) serves as a reference system for restoration projects along lowland sections of large rivers such as the Rhine in the Netherlands

The palaeolimnological potential of diatom assemblages in floodplain lakes of the Danube Delta, Romania: a pilot study

“…Furtheron, it is rather evident that the modern spatial distribution of diatom communities within the Danube Delta is not reflected in the lake classification system suggested by Buijse et al (2002) (Table 2), meaning that the different diatom communities cannot be assigned to a certain lake type. This suggests that the lake ecosystems within the Danube Delta are enormously dynamic and variable and, therefore, it might be problematic to arrange them in a consistent classification system.…”

“…As a result of the seasonal fluctuations of river water fluxes, Danube Delta lakes show a large variability in the light, nutrient and turbidity conditions, and in the occurrence of aquatic vegetation (Coops et al, 1999;. Although lake classification within floodplains is generally difficult, Buijse et al (2002) defined three types of Danube Delta lakes (Table 2) based on differences in trophic state, topography, vegetation, and zooplankton and fish communities. Based on this classification (Table 2), L. Gorgova and L. Roşu represent type 1-lakes, L. Uzlina is a type 2-lake, and L. Gorgovaţ and L. Chiril Mare are assigned as type 3-lakes.…”

“…1). Hydrological characteristics in the delta lakes largely fluctuate caused by seasonal and interannual variability of river and lake water fluxes due to water transport via channels, periodical floodings, and water flow under reed beds (Coops et al, 1999;Buijse et al, 2002). The spatial and temporal variability of hydrological conditions in the floodplain lakes also leads to distinct differences in the plant, fish, zooplankton and phytoplankton communities (Coops et al, 1999;Nãvodaru et al, 2002).…”

Water-level fluctuations affect macrophyte richness in floodplain lakes

“…2) (Middelkoop, 1997). Typically, the highest river discharges occur during December-March and the lowest in August-October (Buijse et al, 2002). After crossing the border of The Netherlands, the Lower Rhine Figure 1.…”

Dynamics of metal availability and toxicity in historically polluted floodplain sediments

“…Proposed measures include setting back dikes, lowering or removing groynes and embankments, extracting accumulated sediments from the floodplains and excavation of secondary channels in the floodplain (Buijse et al, 2002). However, these measures might also have negative consequences because many floodplains contain high concentrations of sediment associated contaminants.…”