1 Introduction - 1.1 Scope of theme: Why care about floodplains?

Rivers are much wider than the channels we associate them with. The areas next to rivers, which are only covered by water during floods, are also part of the river system, acting as the interface between the catchment and the river. Known as floodplains, in their natural condition they are an important ecological part of this system: they filter and store water, secure both natural flood protection and the healthy functioning of river ecosystems, and help sustain the high biological diversity present there. Floodplains are an important part of Europe’s natural capital, covering 8 % of the continent’s area and up to 30 % of its terrestrial Natura 2000 site area. Because they flood regularly, floodplains are naturally highly fertile areas. This combined with the use of rivers for transport has historically made them ideal sites for human settlement and agriculture. Many of Europe’s major cities are located on floodplains and agriculture is linked with an average of 55 % of land use activities there. While they are home to multiple protected species and habitats, they are also now home to 8 % of Europe’s population; in the Netherlands and Hungary this figure rises to more than 20 %.

 

Moreover, in parts of Europe, climate change projections suggest high-intensity rainfall will increase, while in others drought could become more frequent, further affecting the condition of floodplains. In either case, improved ecological integrity is becoming increasingly important and natural floodplains will become key to achieving important policy objectives. These changes have also made floods more damaging — flood waves became higher and now travel faster down the straightened rivers. They also carry larger amounts of fine sediments creating larger deposits than would have been the case under more natural conditions. Further damage has been introduced through the combined desire for flood control, water supply and hydroelectricity, which increased the development of hydroelectric dams and water storage reservoirs, and the control of water flow in rivers.

 

The drive for increased urbanisation and economic growth, and a bigger agricultural area continue to drive change in Europe’s river systems. Public safety from flooding through drainage and flood protection has developed throughout the last centuries, especially after World War II. In addition, Europe’s large rivers are also important transport corridors, supporting trade over large distances. Improvements in navigation have led to rivers being straightened by cutting off meanders and forcing the flow into a fixed channel. These changes have also served as land reclamation projects in which floodplains were drained for greater agricultural production and security of food supply. While these changes have supported both economic growth and flood protection, they have also had serious environmental consequences. The solutions put in place have contributed greatly to disconnecting rivers from their floodplains, greatly reducing their critical roles in flood and drought mitigation, as habitats, and in water quality protection.

 

Estimates made on the Danube, Ebro and Seine rivers and some German rivers suggest that today 70-90 % of Europe’s floodplains are ecologically degraded (EEA, 2016). These changes are of such magnitude that many scientists talk of a regime shift for the ecological functioning of many rivers since the introduction of manmade pressures. Moreover, in the future, high-intensity rainfall is anticipated to become more frequent because of climate change, meaning some countries will be faced with an increased demand for flood protection. In other parts of Europe, the frequency of droughts will increase. During droughts, the water stored in natural floodplains mitigates ecosystem impacts.

 

In 2018, the results of the second river basin management plans were published, among others showing that currently only 42 % of Europe’s rivers achieve good ecological status (EEA, 2018b). Hydromorphological and diffuse pollution pressures are the two main reasons for rivers failing to achieve good ecological status. Both pressures can be reduced through improved floodplain condition. This report provides an overview of the multiple policy and natural resource management benefits that can be achieved by including floodplains more systematically into future assessments and planning in River Basin and Flood Risk Management Plans. We also introduce the notion of ecosystem based management as a unifying concept for managing across policy boundaries.

 

In this first chapter we describe our assessment system and describe the Global and European policy framework that encompasses floodplains. In chapter 2 we provide basic characteristics of the floodplain-river system, and how land use and population in the floodplain is distributed among EEA-39 countries. In chapter 3 we describe some of the key ecosystem services provided by floodplains that support good condition in rivers and of biodiversity together with approaches to river and floodplain restoration and examples of successful restoration projects. In chapter 4 we discuss conditions for successful implementation. Over all the analysis points to a fragmented management approach that would benefit from some streamlining across Europe, in order to better achieve the value of river restoration efforts.

 

This report builds on other publications undertaken by the EEA, in particular EEA, 2016 and EEA, 2017.

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