Riverine flood plains: present state and future trends

Abstract

Natural flood plains are among the most biologically productive and diverse ecosystems on earth. Globally, riverine flood plains cover > 2 × 106 km2, however, they are among the most threatened ecosystems. Floodplain degradation is closely linked to the rapid decline in freshwater biodiversity; the main reasons for the latter being habitat alteration, flow and flood control, species invasion and pollution. In Europe and North America, up to 90% of flood plains are already ‘cultivated’ and therefore functionally extinct. In the developing world, the remaining natural flood plains are disappearing at an accelerating rate, primarily as a result of changing hydrology. Up to the 2025 time horizon, the future increase of human population will lead to further degradation of riparian areas, intensification of the hydrological cycle, increase in the discharge of pollutants, and further proliferation of species invasions. In the near future, the most threatened flood plains will be those in south-east Asia, Sahelian Africa and North America. There is an urgent need to preserve existing, intact flood plain rivers as strategic global resources and to begin to restore hydrologic dynamics, sediment transport and riparian vegetation to those rivers that retain some level of ecological integrity. Otherwise, dramatic extinctions of aquatic and riparian species and of ecosystem services are faced within the next few decades.

Lateral and longitudinal patterns of water physico-chemistry and trace metal distribution and partitioning in a large river floodplain

“…However, a majority of European floodplains has been modified by human actions (Tockner and Stanford, 2002), and rivers are considered to be among the most heavily modified aquatic ecosystems (Carpenter et al, 2011). The value of free flowing rivers for biodiversity and ecosystem services has been widely recognized (Auerbach et al, 2014;Poff et al, 2010).…”

“…Studies looking for main drivers of community changes in floodplains invariably found hydrological variables describing the connection, respectively the isolation from the main channel to be the most important factors (e.g., bacteria (Lew et al, 2016), phytoplankton (Grabowska et al, 2014), macrophytes (Keruzoré et al, 2013), macroinvertebrates (Castella et al, 2015;Paillex et al, 2007), and fish (Daufresne et al, 2015)). However, hydrological connections were often modified by anthropogenic interventions affecting floodplains and large rivers (e.g., Olivier et al, 2009a;Tockner and Stanford, 2002). The re-connection of the floodplain with the main river is often a major aim in river restoration projects (Gregory, 2006;Lamouroux et al, 2015;Muhar et al, 2016).…”

Hydroecological model predictions indicate wetter and more diverse soil water regimes and vegetation types following floodplain restoration

“…Floodplain ecosystems provide an example of how cascading hydrological impacts at a watershed-scale can greatly influence plant species composition. Floodplains are distinctive because they are not only among the most productive and diverse ecosystems on Earth that provide high levels of ecosystem services [Naiman et al, 1993;Ward et al, 1999], but also one of the most degraded [Thoms, 2003;Tockner and Stanford, 2002]. Consequently, restoration of riparian ecosystems by altering hydrology has gained in popularity over the last several decades [Bernhardt et al, 2007].…”

A geomorphic monitoring and adaptive assessment framework to assess the effect of lowland floodplain river restoration on channel–floodplain sediment continuity

“…Because of the significant global loss of floodplain wetland biodiversity, there is a critical need to restore physical processes that sustain function in floodplain rivers (Tockner and Stanford, 2002). This paper illustrates development of a long-term adaptive monitoring and assessment framework for lowland rivers, utilizing results of geomorphic monitoring of a restoration project at the Cosumnes River Preserve as a case study (Figure 1).…”