4.     Hydromorphological pressures and impacts

4.1.    Drivers and pressure of hydromorphological alterations

4.1.1.      Drivers and activities

Hydromorphological pressures comprise all physical alterations of water bodies modifying their shores, riparian/littoral zones, water level and flow, (except water abstraction). Examples of such pressures are damming, embankment, channelization, non-natural water level fluctuations. The extent of hydromorphological alterations in European river basins has been significant over the past centuries. Hydromorphological pressures are the consequence of human activities (drivers) in the catchment area including hydropower production, flood defence structures, navigation, agriculture, land drainage, urban development and fisheries. Hydromorphological changes may result from more than one activity (e.g. a multi-purpose dam for hydropower generation, water supply and flood protection).

Hydrological alterations refer to pressures resulting from water abstraction and water storage affecting the flow regime such as change in daily flow (hydropeaking) and seasonal flow. In addition, river stretches may dry up and water levels of lakes and reservoirs may be heavily regulated. The flow regime of a water body may be significantly altered downstream of an impoundment or an abstraction, and the biology may impacted. Alterations to the flow regime degrade aquatic ecosystems through modification of physical habitat and of erosion and sediment supply rates.

Morphology is the physical structure of a river, lakes, estuary or coast including, for example, the banks and bed of a river and the shore of lakes or coastal waters. Engineering or the way the land is managed can change the morphology of these waters. This has a direct impact on animals and plants and can lead to increased flooding or erosion.

Land reclamation, shoreline reinforcement or physical barriers (such as flood defences, barrages and sluices) can affect all categories of surface waters. Weirs, dams and barrages can alter water and sediment movements, and may impede the passage of migratory fish such as salmon. Using water for transport and recreation often requires physical alteration to habitats and affects the flow of water. Activities such as maintenance and aggregate dredging and commercial fishing using towed bottom-fishing gear can also damage physical habitats.

Agricultural activities have in many places affected the hydromorphological status of European water bodies. Water storage and abstraction for irrigated agriculture have, in particular in Southern Europe changed, the hydrological flow regime of many river basins. Intensification of agriculture included many land reclamation projects affecting transitional and coastal waters and affected many rivers that were straightened, deepened and widened to facilitate catchment drainage and to prevent local flooding.

Reservoirs are human-made lakes created by the damming of rivers to serve one or more purposes, such as hydropower production, water supply for drinking, irrigation and flood protection. During the last two centuries there has been a marked increase in both size and number of large storage capacity reservoirs, especially with the development of hydropower and large basin management. There are currently about 7000 large dams in Europe. In addition, there are thousands of smaller dams. In 2008 hydropower provided 16 % of electricity in Europe and hydropower currently provides more than 70 % of all renewable electricity (Eurelectric 2009).

Figure 4.1: Conceptual overview of the relation between drivers, hydromorphological pressures and habitat and flow alterations.

Inland waterway transport plays an important role in the movement of goods in Europe. More than     4 000 kilometers of waterways connect hundreds of cities and industrial regions. Some 20 out of 27 EU Member States have inland waterways.

Flood defence works may cause significant pressures on hydromorphology. Today many sections of the major rivers have dykes. The building of dykes resulted in the loss of floodplains as retention spaces for flood water. For example, the Upper Rhine 150 years ago had a river bed up to 12 km wide but the river was channel between 200 and 250 m in width. Overall, the natural floodplain area of the Upper Rhine was reduced by 60 %, which in turn entailed considerable expenditure for the associated increased risk of flooding in downstream areas (UBA 2010: Water management part 2).

 In many cases, minerals are extracted from surface water. Sand used to reinforce the coast is extracted from other sea areas, while clay and sand used for concrete and building are usually extracted from the flood plains of rivers. Gravel mining have occurred in several European river basins e.g. in north-eastern Italy, and some rivers of the Carpathians, resulting in  widespread channel adjustments in the last 100 years, in particular incision and narrowing (Rinaldi et al. 2005  ; Surian, 2006; Surian et al., 2008).  

 Hydromorphological pressures, often connected with construction, marine transportation and tourism, are intensified due to population growth and urbanization. Human activities hydromorphologically alter coastal zone, causing considerable changes in physical features of the coast e.g. by accelerating erosion processes. Erosion is significantly intensified by anthropogenic impacts (e.g. coastal defence, land reclamation, vegetation clearing, river regulation etc.), affecting majority of shoreline in Europe. Loss of sediments and space for coastal processes accelerate erosion, which leads to sea-level rise and flooding, loss of material assets and biodiversity. Large-scale structures such as coastal defence constructions and harbours disturb natural circulation of sediments.

4.1.2.      Pressures

Typical hydromorphological pressures that arise in response to the uses (drivers) are the need for impoundment, channel modification, navigation structures etc. and result in specific engineering works such as dams, locks and embankments which change the characteristics of the natural flow regime and the shape of the river channel such as water depth, width, alignment, flow velocity and sediment transport. Examples of relationship between activities and hydromorphological pressures are

• Structures such as dams, weirs and sluices interrupt the longitudinal continuity of rivers.
• The use of water resources e.g. for energy production or abstraction for human uses can impact both the hydrology (e.g. reduced residual water, change in seasonality and hydropeaking) and morphology of rivers (e.g. longitudinal continuum interruption, reduced flow velocities, etc.).
• The disconnection of riverine floodplains and disturbance of the natural lateral connectivity of river systems can frequently result in a decrease of status.
• Navigation activities and navigation infrastructure such as cross profile constructions and impoundments; canalisation; straightening; bank reinforcement and deepening are typically associated with a range of hydro-morphological changes with potential adverse ecological consequences.
• Further, the morphology of rivers has been impacted by the channelisation of river stretches for human uses, erosion of the river bottom as a consequence of reduced sediment transport (due do dams) or dredging for navigation.
• Constructions performed as flood protection measures (lateral dykes, weirs, etc.) also impact the morphology of riverine systems.

These alterations can lead to a water body to be designated as a heavily modified water body (HMWB) if the water body shows substantial changes in character which are extensive/ widespread or profound, and the modifications neither temporary or intermittent and in general alter both hydrological and morphological characteristics.

Impacts of hydro-morphological pressures

The physical modification of water bodies can affect the hydrology of freshwater systems, obstruct up and downstream migration, disconnect rivers from floodplains and wetlands, and change the water flow. The three key components of hydro-morphological pressure are (Figure 4.2):

• change in hydrological regime;
• interruption of river and habitat continuity and disconnection of adjacent wetlands/floodplains; and
• change in erosion and sediment transport.

All these can have various ecological impacts including change and loss of habitat diversity, disruption of species migration and introduction of exotic species. Although the effects may not always be seen locally, they nearly always extend downstream and may also affect upstream reaches and the surrounding areas.

Hydromorphological alteration causes numerous, steeply studied, impacts in coastal zone. The general impact of hydromorphological alteration is reduction of complexity, dynamism and biodiversity (Elosegi et al. 2010). Alteration of coastal habitats causes physical changes that impact the biological diversity (Orlando-Bonaca et al. 2011:7). Coastal habitats have been altered in many ways; forms of hydromorphological alteration as dredging, land reclamation and reshaping to artificial substrate are activities that have weakened living conditions for natural habitats (Crain et al. 2009:40). There is evidence, that artificial structures and HYMO-alteration would develop new habitats for invasive species, while some of the original species disappear. As a result, no dramatic changes occur in biodiversity, but significant changes in composition of species are evident.

Figure 4.2: Conceptual linkage between water uses (storage of water; inland waterway transport and flood protection) and pressures related to physical modifications resulting in changes in hydrological regime, disruption of river continuum and sediment transport and likely ecological impacts

4.2.    European overview of hydromorphological pressures

4.2.1.      Methodology issues

Europe’s surface freshwaters are affected by major modifications, such as water abstractions, water flow regulations (dams, weirs, sluices, and locks) and morphological alterations, straightening and canalisation, and disconnection of flood plains.  These are called hydromorphological pressures. In RBMPs, hydromorphological pressures on surface water bodies were categorized by the Member States into five main pressure groups,

• Water abstraction:  modifying significantly the flow regime of the water body,

• Water flow regulations and morphological alterations:
• River management;
• Transitional and coastal water managementother morphological alterations; and
• Other pressures (including land drainage).

In each of the pressure groups Member States had the possibility to report different hydromorphological pressures such as barriers in rivers or dredging of sediment. However, many Member States (e.g. Austria, Germany, The Netherlands, and United Kingdom) did not report details on pressures and only reported that  a water body was affected by the a pressure group. In addition, Member States did not report in the same pressure groups.

In the following are presented

• First results for water bodies being affected by at least one of the above pressures groups are presented as percentage of water bodies affected by hydromophological pressures.  (i.e. for each water body is checked if it affected by pressures in one of the above pressure groups – these water bodies are identified as being affected by hydromorphological pressures) . A water body may be affected by more than one hydromophological pressure.
• Second results on water bodies  affected by pressures in one of the above pressure groups are presented. Due to different reporting by Member States these results are presented as percentage of the sum of water bodies from Member States reporting the particular pressure group.
• To support the assessment are presented results of percentage of water bodies having altered habitats identified as an impact.

4.2.2.      Key messages

• Hydromorphological pressures and altered habitats are the most commonly occurring pressure and impact in rivers, lakes and transitional waters.
• Hydromorphological pressures affect half of river and transitional water bodies and 30 % of the lake water bodies.
• Coastal waters generally have lower level of hydromorphological pressures and impacts.
• To be further developed

4.2.3.      European results

Surface water bodies affected by at least one hydromophological pressure

Hydromorphological pressures and altered habitats are reported for a large proportions of water bodies in all the water categories, except in coastal waters, where these pressures and impacts are reported for less than 10 % of water bodies (figure 4.3). The proportions of water bodies exposed to hydromorphological pressures are almost the same as those having altered habitats, except for transitional waters were a higher proportion have altered habitats than hydromorphological pressures. In rivers and transitional waters these pressures and impacts are reported for around half of all classified water bodies, while in lakes ca. 30 % of classified water bodies are affected.

Figure 4.3: Percentage of water bodies being affected by hydromorphological pressures or having altered habitats.

Note: Number of Member States reporting hydromorphological pressures or altered habitats is listed in parenthesis.

Source: WISE-WFD database February 2012; wfd.atkins.dk/report/WFD_aggregation_reports/SWB_pressure_status

Overall, 50% European river water bodies, out of around 65 000 river water bodies reported by 19 Member States are affected by at least one hydromorphological pressure.  Also 45 % of the river water bodies have altered habitats identified as an impact.

Overall, 30 % out of more than 12 000 lake water bodies reported by 16 Member States are affected by at least one hydromorphological pressure. Altered habitats were identified as an impact for 22 % of the lake water bodies. This difference can partly be explained by that Sweden has reported lake water bodies being affected by hydromorphological pressures but no water bodies affected by altered habitats.

Hydromorphological pressures are significant in the transitional water bodies, being the second most important pressure (after point sources) affecting 30 % of the transitional water bodies. More than 60 % of the transitional water bodies have altered habitats as an impact.

Hydromorphological pressures are less important in the coastal water bodies of the regional seas around Europe. One tenth of the coastal water bodies are impacted due to hydromorphological pressures. Also around 10 % of the coastal water bodies have altered habitats as an impact.

The hydromorphological pressures in rivers and lakes are reported to be most severe in RBDs in the Netherlands, Germany, Poland, Hungary and south-east England, and less severe in RBDs in Finland, the Baltic countries, as well as in many RBDs in Spain, Italy, Greece,  Bulgaria  and Cyprus (Figure 4.4).

In coastal and transitional waters the hydromorphological pressure is mainly a problem at the Estonian and German Baltic coast; along the Greater North Sea coast of Germany, the Netherlands and Belgium, as well as the in the northern/Basque coast of Spain and southern coast of Italy (Figure 4.4).

The highest share of transitional water bodies with hydromophological pressures has the Greater North Sea region, followed by the Mediterranean Sea region. The Celtic Seas, Bay of Biscay and the Iberian Coast region has 23 % of such water bodies, which is somewhat below the EU average. No hydromophological pressures were reported in the Baltic Sea and Black Sea regions.

The Mediterranean Sea and the Greater North Sea regions have more than 10 % of coastal water bodies under HYMO pressures (16 % and 13 % respectively). The Celtic Seas, Bay of Biscay and the Iberian Coast region has 9 % of such water bodies, which is slightly below the EU average. The Baltic Sea region has 4 % of such water bodies.

Figure 4.4  Proportion of water bodies in different River Basin Districts affected by hydromorphological pressures for rivers and lakes (left panel) and for coastal and transitional waters (right panel). 

Note: percentage, based on number of classified water bodies

Source: WISE-WFD database February 2012; wfd.atkins.dk/report/WFD_aggregation_reports/SWB_pressure_status

 4.2.4.      Hydromophological pressures groups

Rivers

Of the 20 Member States reporting pressure information for rivers

• 17Member States reported water bodies affected by water abstraction:;

• 19 pressure from water flow regulation and morphological alteration;
• 16 reported pressure from river management,  and
• 8 reported other morphological pressures (mainly pressures related to barriers).

Nearly 40 % of the river water bodies are affected by water flow regulation and morphological alteration (Figure 4.5). This pressure group includes impacts from storage of water in reservoirs, but also change in hydrological regime and impacts by weirs and locks. Member States has also reported impact of barriers under the other morphological alteration group affecting 5 % of river water bodies.

The second most important pressure group is river management being a pressure affecting 23 % of river water bodies. The pressure group river management includes water bodies physical alteration of the river channel including effects of dredging, land drainage and barriers due to bridges, culverts etc.

Nine percent of the river water bodies are affected by water abstraction (see also chapter 6).

Figure 4.5 Percentage of water bodies per water category being affected by hydromorphological pressures in main pressure groups

Note:

Source: WISE-WFD database February 2012; wfd.atkins.dk/report/WFD_aggregation_reports/SWB_pressure_status

Lakes

Of the 20 Member States reporting pressure information for lakes (Sweden has not reported surface water bodies being affected by hydromophological pressures)

• 15Member States reported water bodies affected by water abstraction:;

• 14 pressure from water flow regulation and morphological alteration;
• 9  reported pressure from river management,  and
• 6 reported other morphological pressures (mainly pressures related to barriers).

For lakes water flow regulation and morphological alteration and river management were the two most important pressures affecting 27 % and 21 % of the lake water bodies. Only few lake water bodies was affected by water abstractions and other morphological pressures was identified for 9 % of the lakes.

Transitional and coastal waters

Four Member States (UK, France, Spain and Italy) have identified transitional water bodies being affected by water abstraction in the river basin district; accounting for 12 % of the transitional water bodies in these Member States. High water abstraction or water storage in the river basin district may markedly reduce the freshwater inflow, in particular in summer, and the dilution of pollutant discharges.

For transitional and coastal waters 6 to 8 Member States reported water bodies affected by the two main pressure groups water flow regulation and morphological alteration; and transitional and coastal management. The pressure groups generally affected 10 to 15 % of the water bodies. The pressure group transitional and coastal management include pressures related to land reclamation and dredging.

4.2.5.      Country results

Countries with a high proportion of river and lake water bodies being affected by hydromorphological pressures are found in central Europe (Figure 4.4). Figure 4.5 shows the percentage of classified water bodies per water category and country the percentage of water bodies being affected by hydromorphological pressures or having altered habitats as an impact.

The Member States are in Figure 4.5 ranked by the percentage of water bodies achieving at least good ecological status or potential, for coastal and transitional waters the ranking are for the sea regions. Estonia has, for example, the highest proportion of river water bodies with good ecological status or potential, while Belgium (Flanders) has the worst status. Both for rivers and lakes there are good agreement between the ranking by proportion of water bodies with good status and the proportion of water bodies affected by hydromorphological pressures and haltered habitats. Member States with high proportion of good ecological status also generally have lower proportion of water bodies being affected by hydromorphological pressures or altered habitats.

 Half of the 20 Member States (no pressure and impact data from Luxembourg, Slovakia and Romania)  had more than 40 % of their river water bodies being affected by hydromorphological pressures (Figure 4.5); and six countries Poland; Germany; Belgium Flanders; Poland, the Czech Republic and The Netherslands had more than 60 % of river water bodies being affected by hydromorphological pressures. Member States with a high proportion of water bodies impacted by hydromorphological pressures also had a high proportion of water bodies with altered habitats as impact.

Five Member States, Belgium Flanders, The Netherlands, Czech Republic, United Kingdom and Hungary had more half of the lake water bodies being affected by hydromorphological pressures and altered habitats being an impact. This partly reflects the high number of reservoirs in these countries.  Most other Member States report around 20-30 % of the lake water bodies affected by hydromorphological pressures.

Of the few transitional waters in the Baltic Sea no water bodies were reported having hydromorphological pressures or altered habitats (Figure 4.5). All the transitional water bodies in Germany, The Netherlands and Belgium at the Greater North Sea coast have hydromorphological pressures; while 40 % of the UK and French transitional water bodies at the North Sea have hudromorphological pressures.

 In the Mediterranean and Celtic Sea and Iberian coast the Member States reporting pressures and impacts at transitional waters identified that around 40 % of these water bodies are affected by hydromophological pressures and altered habitats.

Most countries reported less than 20 % of the coastal water bodies being affected by hydromophological pressures and having altered habitats. In the Netherlands, German North Sea coast, Estonia, Malta and Italy more than a third of the coastal water bodies have hydromorphological pressures or altered habitats.

Figure 4.5 Percentage of surface water bodies being affected by hydromorphological pressures A) Rivers; B) Lakes; C) Transitional waters; and D) Coastal waters

Note: Percentage of water bodies with hydromorphological pressures being a significant pressures and altered habitats being a significant impact

4.3.     Case studies

We hope that Member States and relevant stakeholders will comment on the current case studies and contribute with updates and new case studies. The current case studies are partly copy and paste from RBMPs or other relevant documents

4.3.1.      Case study: Danube, Rhine, and Rhône rivers heavily impacted by hydro-morphological pressures

Source: ICPDR, 2010 and Umweltbundesamt, 2010

Like many other European rivers, the Danube and Rhine are heavily influenced by human activities including intensive navigation and habitat modification by hydraulic engineering. The natural structure on many stretches of the rivers has been changed, including their depth and width, flow regimes, natural sediment transport and fish migration routes.

Dams and reservoirs have been built in nearly all mountainous areas and some lowland regions of the Danube Basin and navigation channels, dykes and irrigation networks are widespread in the lowlands along the middle and lower reaches of the river.

• more than 80 % of the Danube is regulated for flood protection, and about 30 % of its length is impounded for hydropower generation;
• about half of the Danube tributaries are used to generate hydropower. The generation capacity of all the hydropower plants in the Danube Basin is almost 30 000 MW;
• more than 700 dams and weirs have been built along the main tributaries of the Danube;

along the Rhine, water meadows between Basle and Karlsruhe have shrunk by 87 % following construction of dykes and channels to cut off meanders.

 The Rhône River,

Source: Souchon 2007

Over the last 400 years the Rhône was developed in successive phases for different purposes, levees have been built as flood defences; and groins and ripraps were constructed to create a more navigable river. The basin has 19 hydroelectric schemes accounting for 20-25% of the French hydroelectric production. Water abstraction for irrigated agriculture has added to the many river uses. Canals straighten and shorten the watercourse to facilitate navigation, thus by-passing the old river channel (“vieux” Rhône).

Today the flow regime of the Rhone is regulated by several large storage reservoirs that can hold more than 7 % of the annual runoff. Nearly 80% of this storage capacity is located downstream of Geneva.

 The Rhône corridor is today a densely populated and industrialized area. The morphology of the river channel has changed from braided to straight and canalized, often eroded and incised; the level of the ground water has been lowered; several natural biotopes disappeared; the riparian forest evolved to hardwood forest due to ground water depletion; and dams block the migration of fish (shads, eel, lampreys), where numerous lateral communications with tributaries or side channels have been modified, sometimes cut off.

4.3.2.      Case study: Shannon RBD, Scottish RBD and Irish Estuaries

Shannon RBD

Source: Shannon RBMP

Many of the surface water in the Shannon RBDs have physically been modified for water supply, recreation, transport, flood protection, hydropower, aquaculture and land drainage.  There are in the RBD around 95 000 culverts and bridges on our rivers, almost 900 kilometres of river embankments, 19 large water reservoir or hydropower dams, 10 large ports and over 200 kilometres of coastal defences.

 Scotland RBD

Source: Scotland RBMP

The Scottish RBMP identified just under 14 % of our surface water bodies as  heavily modified water bodies and being substantially changed in character for purposes such as flood protection, hydropower generation, navigation, land drainage or water storage for drinking water supply. These are known as. Another 1% of surface waters are artificial.

Pollution pressures were affecting 18 % of the length/area of surface water bodies while the different hydromophological pressures: Alterations to water flows and levels; Modification of beds, banks and shores and Barriers to river continuity for fish migration affected 18 %; 16 % and 14 % of the surface water bodies, respectively.

 In the Scottish RBD five types of morphological impacts have been identified as significant water management issues. Table 33 provides the lengths/areas of water bodies affected by each issue. The number of water bodies is given in brackets.

Many of Scotland’s freshwaters display a history of engineering interventions. Examples include:

• •        diverting and canalising rivers to utilise floodplains;
• •        culverting to improve drainage or enable development;
• •        building embankments to prevent flooding;
• •        bridging waterways for transportation.

 Table 12 below lists the principal pressures that are adversely affecting water flows and levels in Scottish rivers and lochs. There was not identified any significant impacts on water flows in estuary and coastal water bodies. There are two main types of pressure on water flows and levels; impoundment of rivers by damming to create a water storage reservoir; and direct abstraction without impoundment.

The main activities for which reservoirs have been created are drinking water supply and hydropower generation. Water flows and levels in the reservoirs and in the rivers immediately downstream of the reservoir dams are altered by the impoundment of the water in the reservoir and its subsequent abstraction. Reservoirs used for hydropower generation are concentrated in the uplands of the central and northern parts of the Scotland RBD. Those for drinking water supply are typically found nearer to the larger towns and cities towards the south of the Scotland RBD.

 The main direct abstractions without impoundment are for irrigating crops or providing drinking water. The impacts of these activities are concentrated along the east and north-east coasts. Direct abstractions are also used for drinks production and fish farming.

Hydromorphological alterations of Irish estuaries

Source: Hartnett et al. 2011

Estuaries in Ireland, as elsewhere, have long been subject to the consequences of the full range of human activities. These include reclamation of saltmarsh and mudflat, modifications (e.g. canalisation, dredging) for shipping and transport along with the discharges and dumping from such, extraction of renewable natural resources such as fisheries, and of course the discharge of domestic and industrial wastes. All these changes have impacted on the functioning of estuarine system. The estuaries along the east coast of Ireland show the greatest morphological modification.

4.3.3.      River basins in West Balkan heavily affected by hydromorphological presures

Skoulidikis 2008 described the envirironmental state of 15 major Balkan rivers covcring more than 80% of the inflows in Eastern Mediterranean. Many of the rivers are heavily affected by hydromorphological pressures.

In the 1950s, the first large dams were constructed and today most rivers are “strongly fragmented” by dams and flow regulation. The most modified river is the Acheloos. The Evros, Axios, Pinios, Alfeios and Aoos are “moderately fragmented”, while only Sperchios and Evrotas are free-flowing. Over the past 40–45 years, the Balkan rivers have undergone marked discharge reduction, caused by climate variability and change, evaporation from reservoirs and extensive water abstraction for irrigation. For example, i the n Pinios basin, intensive use of water for agriculture deteriorated the water balance, which is strongly negative even in rainy years (Loukas et al., 2007) and resulted in lowering of the groundwater table by tens of meters (Marinos et al.,1997). In summer, river stretches in Pinios may dry out. Since the end of the 1990s, the water level of Lake Doirani has been receding as a result of drought and overexploitation for irrigation (Griffiths et al., 2002). Dam operation smoothes and modifies the hydrological regime downstream of reservoirs. Thus, Acheloos, Nestos and Aliakmon nowadays present high to maximum discharge in July due to peak hydropower production. In Acheloos, 30% of the annual flow occurs during summer (compared to 11% prior to dam construction). In several places  reservoirs retain vast masses of sediments thus adversely affecting delta evolution.

Large wetland areas were drained in favour of widespread intensive agriculture. In the past 50 years, huge drainage and irrigation networks were established and inter-basin water transfer projects took place, e.g. from Trebisnjica River to the Neretva and from the Strymon and Nestos headwaters to the Iskar and Evros basins (Knight and Staneva, 1996). Agricultural development and reservoir construction resulted to dramatic morphological modifications in water bodies. Some lakes and extensive marshes related to river deltas  have been drained. Thus, Greece lost 60–70%, of its original wetlands (Tsiouris and Gerakis, 1991).

4.3.4.      References

Hartnett, M., Wilson, J. G.,  and Nash, S. 2011: “Irish estuaries: Water quality status and monitoring implications under the water framework directive,” Marine Policy In Press, Corrected Proof (n.d.), http://www.sciencedirect.com/science/article/B6VCD-526YMMH-1/2/e885524f9f4821a7046ea112b6197af3.

ICPDR, 2010

Nikolaos Th. Skoulikidis, “The environmental state of rivers in the Balkans—A review within the DPSIR framework,” Science of The Total Environment 407, no. 8 (April 2009): 2501-2516.

Source: Souchon 2007: The Rhône river: hydromorphological and ecological rehabilitation of a heavily man-used hydrosystem. Available at http://www.uicnmed.org/web2007/cdflow/conten/2/pdf/2_1_France_%20MedCS.pdf

Scotland River Basin Management plan available at http://www.sepa.org.uk/water/river_basin_planning.aspx

Umweltbundesamt, 2010