3.2 Status of Europe’s floodplains: remaining areas and environmental quality

please provide general comments on section 3.2 here

When assessing the status of Europe’s floodplains it is important to look at the location and remaining areas of floodplains, but at their functionality and at the quality of the ecosystem services they provide too.

3.2.1        Today’s floodplains in Europe

In Europe already up to 90 % of the former riparian floodplains have been lost during the last centuries or they are functionally no longer intact (Tockner, et al., 2009, 2002). The main reason for the loss of active floodplains is the continued decline in floodplain area due to flood protections to prevent land uses not or less compatible with inundations (such as agriculture, or urban expansion), or infrastructure for hydropower development or maintenance of shipping channels (see section 3.3).

For example in Germany, where a national inventory accounted 70 to 90 % of floodplain area loss along 10 000 kilometres of 79 larger rivers and streams of 8 river basins (BMU and BfN 2009; Brunotte, et al., 2009). For the larger rivers, the loss is around 90 % of the 15 000 km² there once was, and in general only 1 % to 2 % of the former morphological floodplain is currently covered with near-nature floodplain forest (Brunotte, et al., 2009). For the different river sections of the Danube River the floodplain area loss varies between 73 and 95 %, where the Danube delta only lost around 30 % (Schneider, 2010; Schneider, et al., 2009). When including the tributaries, the floodplain loss can be estimated at 80 % (see table 3.1).

Table 3.1        Examples for Floodplain area loss along large rivers in Europe

Sources: (a) (Schneider, et al., 2009) (b) (Brunotte, et al., 2009) (c) (Haraszthy, 2001), (d) (Schmid-Breton, 2015) (e) personal communication Tom Buijse, Deltares (NL) (*) (f) (Tockner, et al., 2009),  (g) (WWF Germany 2000) (h) (Ollero, 2010)
(*) reference to be updated

The remaining floodplains in Europe are very often far away from being functionally intact, and are faced by a multitude of hydraulic measures or separated from the riverbed by summer levees. Despite these alterations, the fragments of remaining floodplains are important areas for nature conservation: more than 30 % of all classified riparian zones are protected under EU law (Clerici, et al., 2013), i.e. are part of the Natura2000 network.

At the European scale no floodplain inventory or systematic assessment on floodplain status has so far been made. Floodplain loss and assessment of its quality is not registered or reported in a consistent way in the EU. With new spatial data reported under the European Floods Directive (EU 2007), combined with Corine Land Cover (CLC) data as well as information reported under the Habitats Directive (EU 1992), potentially new overviews will be possible but still these will have limitations (see subsection 3.2.2)

Where the German floodplain inventory (see Box 3.1) contains information of remaining and former floodplains of larger rivers, the Austrian (Lazowski, et al., 2014) and the Swiss (Hausammann, et al., 2005) inventories focus on the remaining high value areas. The latter contains a multitude of spatial, hydromorphologic, habitat and management information, including threats and pressures on the selected floodplain areas.

Table 3.2        The five classes of floodplain status with a condensed specification

Source: (Brunotte, et al., 2009)

Figure 3.1: Comparison of the distribution of the floodplain status classes

Note: for all assessed sections of active floodplains (left) with former floodplain areas (right)

3.2.2        Distribution of floodplain areas

To get an overview where active floodplains still occur, reported flood hazard and risk maps (FHRMs) (EU 2007, Art. 6)are used as proxies. The medium probability flood hazard maps, all with a likely return period of 100 years ([1]), for nine countries (see table 3.3) overall covers around 5% of the total area of these countries, with significant differences from country to country. Under 2% of the country territory for the Czech Republic, Austria and Slovenia up to over 10% for Romania, Italy and Hungary is mapped as being part of the medium probability flooded area. In Germany, more than 6 % is mapped as belonging to the flooded area of this scenario. This is slightly more than the national floodplain inventory but incudes more rivers. It should be noted that important floodplain areas along the Danube were not included in the FHRMs and that it was not always possible to clearly distinguish between river floodplains and coastal flood-prone areas.

Table 3.3        Medium scenario flood hazard maps for selected countries as a proxy for floodplain occurrence

^(a) Danube floodplain is missing
^(b) Some flood hazard areas especially closely to the coastline close to the North Sea (DE) or Baltic Sea (DE, PL) are clearly prone to sea flooding
^(c) Data obtained from national portal

Source: reporting obligation of flood hazard and risk maps for the Floods Directive (EU 2007), http://rod.eionet.europa.eu/obligations/602

The nine countries (see table 3.3) with spatial information on flooded areas available, consist of 4029 subcatchments (catchments with fourth Straler order CCM2/WS04 (JRC 2008)) with an average area of 383 km². Higher floodplain coverage (see Map 3.1) is significant for subcatchment for the Italian rivers Reno, Arno, Po, the Croatian parts of Sava and Drava rivers, the Tisza river in Hungary, the Elbe river in northern Germany and the Danube river in the eastern Romania.

Map 3.1          Floodplain distribution

Note: Percentage of flood hazard area (medium probability) per subcatchment used as a proxy for floodplain coverage

Land uses in floodplains

An intersection of the medium scenario flood hazard maps with the land uses types is shown in Figure 3.2. The 15 land use types are aggregated from the Corine Land Cover types on level 2 and3 (EC and EEA 1995), providing most detail on forest, semi-natural areas and wetland and being more aggregated for artificial surfaces ([2]). More than 40% of the floodplains are used for arable farming, being almost exclusively (over 99 %) non-irrigated. With 57 % (or 16 000 km²) the highest absolute coverage of arable land in floodplains of the nine selected countries can be found in Italy. The vast majority of these areas are located in northern Italy within the Po and Reno catchments (Map 3.1).

[2] Corine Land Cover 2006 seamless vector data, see http://www.eea.europa.eu/data-and-maps/data/clc-2006-vector-data-version-3 online

Figure 3.2       Share of land use types in floodplains

Note: for nine countries: AT, CZ, DE, HR, HU, IT, PL RO and SI, see Table 3.3 with flooded areas under the medium scenario in the FHRMs as a proxy for floodplains.

Pastures are covering almost 13.5 % of total floodplain area for all nine countries together. In Poland, pastures cover around one third of floodplains, making it the most present land use category in the floodplains for this country and with pastures equally distributed over Oder and Vistula catchments.

Forests cover around 9 %, where Croatia has the highest floodplain coverage with forests (nearly 30 %). Italy and Hungary only reach around 4 % of forest and all other countries in this exercise are close to the average of 10 % forest coverage.

Inland wetlands in floodplains reach in total about 4 % of the floodplain area, where Romania (with around 15%) reaches the highest cover for this land use category. Artificial areas, being mostly urban areas, cover around 6% of the assessed floodplains 6 % with large differences in between countries: from 25% in Austria and 14% in the Czech Republic to roughly 4% in Hungary and only 2% in Croatia.