Effects of river regulation on floodplain biodiversity

Posted on December 18, 2015

The natural flow regime of a river has a key influence on the ecology and biodiversity of its floodplain ecosystems. River regulation, in the form of infrastructure for water supply, irrigation, flood mitigation, power generation and other functions, can drastically modify streamflow patterns. Despite the impact of river regulation on flow there have been surprisingly few attempts to quantify its effects on floodplain biodiversity, and as a result it’s been difficult to include river regulation in models of environmental change. To redress this situation, Dutch researchers carried out a meta-analysis of 28 studies on the ecological consequences of altered flow regimes. As well as flow, they also took account of potential modifying factors, namely the type of organism affected (mammals, birds, fish, invertebrates, plants), the type of local terrestrial ecosystem, and the extent of land development. They measured ecological impact in terms of changes to mean species abundance and species richness. River regulation had strongly significant effects on both of these measures, reducing mean species abundance by over 50% and the number of species by more than 25% on average. Although there was a general increase in ecological impact with the amount of regulation (low, medium or high), species richness seemed to be relatively tolerant of low-level disturbance. The type of organism, the type of ecosystem and land use were also influential, but were less important than river regulation. Animals responded most strongly in terms of abundance while plants responded most strongly in terms of species richness.

Reference: Kuiper, J.J. et al. 2014. The impact of river regulation on the biodiversity intactness of floodplain wetlands. Wetlands Ecology and Management 22, 647–658.