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PREFACE
In accordance with Article 4 (3), the Water Framework Directive (WFD) allows Member States to identify surface water bodies which have been physically altered by human activity as "heavily modified" under specific circumstances. If the uses of such water bodies (i.e. navigation, hydropower, water supply or flood defence) would be significantly affected by the mitigation measures required to achieve good ecological status and if no other better environmental options exist, then these water bodies can be designated as "heavily modified" and good ecological potential is set as an environmental objective.
As part of the EU WFD Common Implementation Strategy (CIS), a working group has been established to develop guidance on the process of HMWB designation. The CIS working group 2.2 on "Heavily Modified Water Bodies" (HMWB) is jointly managed by the United Kingdom and Germany and involves the participation of the 12 Member States (MS) Austria, Belgium, Denmark, Spain, France, Germany, Greece, Netherlands, Portugal, Sweden, Finland and UK, and in addition Norway. There are two distinct "sub projects" being progressed by the working group:
- case study projects in participating MS;
- synthesis of the case study reports and drafting of common implementation strategy HMWB guidance.
- Case Study Projects
The case studies include the description of the physical alterations resulting from identified uses of the water bodies and resultant ecological impacts; provisional identification of HMWB; undertaking the designation tests and definition of ecological reference conditions (maximum ecological potential) and objectives (good ecological potential). Case study projects started in October 2000 and have been focusing on the main water uses (navigation, flood/coastal protection, hydropower generation, agriculture and water supply) that result in physical alterations across the MS. There are 32 case studies which had to be completed by 15th February 2002.
European Synthesis Project
This project performs an analysis of the case studies and a synthesis of approaches taken in the individual case studies, identifying commonality and differences in approach. The analysis started in February 2002. The synthesis report will form the basis of the production of guidance and will provide examples of how the designation process should work.
CASE STUDIES
River Weinfluss (Austria). (428kB)
The case study focuses on the Wienfluss which runs through the city of Vienna with a population of about 2 million inhabitants. The river section of the Wienfluss has a length of about 34 km with a catchment area of 94 km2. The focus of the case study is concentrating on alterations of flood protection which have the main impact on the Wienfluss river system in terms of channelisation and impoundment. Besides flood protection, urbanisation is another main use in the case study river section. The history of river regulation in the Vienna section of the Wienfluss is closely related to urban development which started in the 19th century in a large scale. Additionally, Wienfluss has been chosen as a case study due to the variety of rehabilitation measures which have already been carried out and have led to improvements of the ecological conditions within this river section.
River Rhone (France). (200kB)
The River Rhone valley is the largest hydrosystem of the Rhone-Mediterranean-Corsica basin (covering 70% of the total 130,000 km2 basin area). Its source in Switzerland, where its catchment basin is 8,000 km2. The Rhone was chosen as a test area for the Heavily Modified Water Bodies project because it has a relatively complete range of pressure and activity features typically seen in various rivers of southernmost France. Moreover, it is one of the most studied rivers and has a dense monitoring network of water quantity and quality measurement stations. Since ancient days the Rhone has been a major hub of human activities, some of which are of critical importance at national level (e.g. hydro-power production and inland navigation). Still today, its valley is a social and economic powerhouse articulated around the Lyons conurbation and its industry. The physical alterations described in the case study are linked to hydro-power, navigation, urbanisation and flood defence. As a major river where several environments, features and interests meet, the Rhone draws the attention of numerous stakeholders directly or indirectly involved in strategic discussion and/or decision making for concerted management of the resource.
River Kennet (UK). (1Mb)
The River Kennet is the largest tributary of the River Thames in south-central England. It represents a river that has many uses and pressures from human activity. These include navigation, flood defence, groundwater abstraction, land drainage and other management for agriculture, fisheries (commercial and recreational), heritage such as old mill structures and some degree of urbanisation. It also receives effluent from sewage treatment works, and its catchment, especially the floodplain area, are high quality agricultural land. Despite these pressures the ecological status of the river is generally considered to be good. The Kennet valley also contains nationally important wildlife sites and habitat types; there are 55 Sites of Special Scientific Interest (SSSIs) designated by English Nature within the Kennet catchment.
River Danube (Austria). (454kB) The River Danube is one of the main rivers of Europe (total course 2850 km). The Austrian case study on the River Danube focuses on the impounded Austrian Danube section between Greifenstein and Vienna (50 km). The case study comprises a combination of different uses; besides navigation, flood protection and urbanisation, hydropower generation is the main use. The case study area of the river section is characterised by two hydropower stations, bank reinforcement and hydrologically isolated large floodplain areas. Another important aspect of this study is that a variety of rehabilitation measures have already taken place, resulting in improvements concerning the ecological status. The Danube case study belongs to the hydropower sub-group.
River Bregenzerach (Austria). (120kB) Bregenzerach is an alpine river and tributary to the Lake Constance. This case study serves as an example for a river significantly impacted by hydropower peaking and diversion-type power stations causing several hydromorphological changes such as reduced flow in the river bed. A variety of rehabilitation measures, e.g. re-regulating reservoirs, flow management system introduced to reduce peak amplitudes have resulted in improvements of the ecological status of the upstream river section, while the downstream part is still considerable affected by hydropower peaking.
River Dender (Belgium). (760kB)The case study covers the lowland River Dender as well as its tributaries, Mark and Bellebeek. The river basin of the Dender is part of the catchment area of the River Schelde. The Dender is a border-crossing river between the region of Flanders and Walloon in Belgium, therefore collaboration between the regions is required. The case study area is influenced by different types of pressures such as flood protection, navigation, urbanisation and agriculture as well as various physical alterations such as canalisation, straightening and dams. Due the geology in the case study area, the stream discharge has a quick response to rainfall events. However, exceptional discharges of e.g. 60 m³/s in wintertime or 0 m³/s in summertime are caused by canalisation and the locks.
River Dhünn (Germany). (1.2 MB)The River Dhünn is a medium sized river located in the mountainous region of north-western Germany. It is the major tributary to Wupper, which shortly after their confluence enters the River Rhine. The upper 60 km2 of the Dhünn catchment are captured by a deep reservoir for drinking water supply of the Ruhr region, one of the most densely populated areas throughout Europe. The case study was chosen to find out whether the stretch downstream of a dam has to be designated as heavily modified or whether this designation should be restricted to the dam.
River Mulde (Germany). (1.3MB)The River Zwickauer Mulde (127km) is an important tributary of the River Elbe rising from the central mountains in middle-east Germany. It comprises a large catchment with different stream types and landscape areas. It flows through a historically industrialised region impacted by various pressures such as urbanisation, water supply with several reservoirs, hydropower generation as well as former uranium mining. For the case study a study area (65 km) in the middle reach including the city Zwickau was selected.
River Elbe (Germany). (1.2MB)The River Elbe is one of the biggest rivers in central Europe with its springs in the central highlands of the Czech Republic. Today, the entire German Elbe is a national waterway with Hamburg as the most important harbour of Germany. For this case study two representative sections were selected, one in the upper and one in the middle Elbe. The stretch from the Czech-German border up to Pirna (34 km) reflects typical impacts of navigation, while in the stretch between Magdeburg and Geesthacht (250km) flood protection prevails. Throughout the entire Elbe, water quality remains a problem.
River Lahn (Germany). (290kb) The River Lahn (244 km) is a tributary to Rhine and represents a typical low mountain range river. Main impacts in this case study are hydropower generation and navigation. Overall, more than 22 river hydropower stations and over 50 weirs, many of them not passable for aquatic organisms, are located along the river. Navigation becomes more important within the last 150 km before merging into the Rhine and therefore this downstream section had been strongly developed (canalisation, river bank fixation, weirs and sluices). In 1981, traffic of goods had been discontinued and nowadays passenger and recreational navigation prevails. This case study belongs to the hydropower as well as to the navigation subgroup.
River Seefelder Aach (Germany). (2.4MB) The Seefelder Aach in south-western Germany is a tributary to Lake Constance. Seefelder Aach was chosen as a case study because of strong impacts due to intense hydropower production. Twelve hydropower plants and five additional weirs are disturbing the migration of aquatic fauna, especially of the lake trout (Salmo trutta). Furthermore, intensive agricultural land-use, including fruit and vine-growing, have already led to large-scale alterations regarding land-drainage and river regulation.
River Ruhr (Germany). (880kb)The River Ruhr, a tributary of the River Rhine, is situated in the mid-western part of Germany with a length of 219 km. The “Ruhrgebiet” located in the western part of the catchment is one of the largest industrial areas in Europe, including the large inland harbour of Duisburg. The water of the Ruhr serves as drinking water resource for over 5 million people and as industrial water supply. To enable water supply, 14 reservoirs with dams have been built in the upper catchment also used for hydropower generation. Hence, this case study focuses on the impacts of water supply and belongs to the hydropower subgroup.
River Lozoya (Spain). (290kb) The River Lozoya rises in the central mountain range in high altitude and cuts through steep relief joining the River Jarama at 710 m a.s.l. The Jarama is a main tributary of the Tajo, the longest river in Spain with the greatest discharge capacity. Lozoya is an example of a Spanish river that has been significantly altered by the construction of a series of reservoirs, serving for nearly 50% of the total water supply for the metropolitan area of Madrid and to a lesser extent for hydropower generation (five hydropower plants). Nowadays, roughly fifty percent of the river's length is taken up by reservoirs. Other pressures, such as adjacent agriculture, forestry and human settlements, are of little importance. The Lozoya falls into the hydropower sub-group based on the type of physical alterations affecting it, i.e. the dams.
Lake Kemijärvi (Finland). (436kb) Lake Kemijärvi is the largest natural lake within the catchment of the River Kemijoki. Kemijoki is the longest river in Finland and is situated in Lapland. Lake Kemijärvi is the most heavily regulated lake of Finland and most of the harmful effects of regulation are obviously visible. The main objectives of regulation are hydropower production and flood protection. Other human activities in the drainage area include forestry, farming, husbandry and fish farming while some pollution is also caused by wood pulp industry and settlements. Water level regulation of Lake Kemijärvi has a maximum amplitude of 7 m, which is the largest regulation amplitude encountered in Finnish lakes, and has caused harmful impacts on the littoral vegetation, the benthic invertebrate fauna biomass and fish stocks. The lake strong spring floods have been cut off by water level regulation allowing for higher winter discharges for hydropower. On the other hand, summer water levels are raised due to higher storage capacity. The HMWB project on lake Kemijärvi is within the context of a large study aiming to identify Finnish regulated lakes based on water level fluctuation and biological characteristics.
As a sub-study of this HMWB case study, water body identification has been carried out in the main stream of the River Kemijoki downstream of lake Kemijärvi. This part of the river consists of 8 power plants and run-off-river impoundments. The pressures of human activities on the River Raudanjoki, a large tributary of Kemijoki below Lake Kemijärvi, have also been identified.
River Authie (France). (792kb) The River Authie in northern France of 95 km length and flows into the Channel. It is mainly affected by a series of water mills for different uses (electricity, fish farms) with small dams of 0,5-2m height which hinder fish migration. Further impacts derive from large scale agriculture, urbanisation and recreation. The low and central valley of the river has been proposed as site of Natura 2000 network (potentially protected area).
River Sarre (France) (340kb) case study in French language
River Nestos (Greece). (840kb) The River Nestos is an international river of 234 km length with its spring in south Bulgaria, continuing its flow through Greece and finally discharging into Agaeis forming the ecologically valuable Nestos Delta. The case study focuses on the Greek part of the river (130 km) with two large hydropower stations upstream with the reservoirs also serving water supply and irrigation and a third one under construction further downstream. The Nestos Delta is under the protection of the RAMSAR treaty for wetlands but it is heavily impacted by agriculture, land drainage and river straightening, which resulted in a discontinuation of recent delta formation. The Nestos study belongs to the hydropower sub-group.
Haringvliet Estuary (NL). (1.8MB) This case study represents an example for transitional waters with a strong influence by human activities and substantially changed character. The rivers Rhine and Meuse form a combined estuary in the south-west of the Netherlands. The northern outlet of the Estuary is the Rotterdam Waterway. The southern outlet is the so-called Haringvliet Estuary, which is the focus of this case study. After completion of the Haringvliet Dam in 1970, this area changed from a dynamic brackish tidal inlet into a semi-stagnant freshwater area. The flow regime is regulated by sluices to ensure a minimum water flow in the Rotterdam Waterway. Actually, there are plans to open/remove the Haringvliet Dam in the future in order to restore the estuary system. Main pressures in the case study area are navigation, flood protection and agriculture. This case study belongs to the navigation subgroup.
River Hagmolenbeek-Hegebeek (NL). (2.0MB) Hagmolen-Hegebeek is a small transboundary stream (length 27 km), located in the eastern part of the Netherlands at the border to Germany. This case study was chosen because it represents a typical lowland stream of the Netherlands significantly impacted by agriculture. The stream has been changed by channelization, the building of weirs and drainage in the catchment to optimise the hydrological conditions for agricultural use. Since the building of the Twente Canal (1936) for navigation, the Hagmolen-Hegebeek has been cut off the catchment of the stream Regge and flows directly into the Canal.
Lake Loosdrecht (NL). (1.1MB) Lake Loosdrecht (10 km2) has been selected as a typical example for a Dutch peat lake and is part of a system of shallow interconnected lakes in the centre of the Netherlands. While former industrial peat mining created the preconditions for the creation of the Lake, natural processes formed the present lake. It is heavily impacted by recreation, especially recreational shipping and by the construction of unnatural embankments to prevent further erosion of the peatbanks. A further problem is eutrophication and water quality.
Lake Veluwerandmeren (NL). (356kb) The Veluwerandmeren is a Dutch shallow freshwater lake system influenced strongly by hydromorphological changes. It consists of four connected lakes: Veluwemeer, Drontenmeer, Wolderwijd and Nuldernauw. These were created by the reclamation of a polder and the building of dikes at a former estuary. Due to many hydromorphological impacts, Veluwerandmeren has no stable period of relatively undisturbed ecological functioning. Main use of the lake is fisheries and recreation accompanied by heavy recreational shipping, as well as water supply (for irrigation and industrial processes). It has been designated as a protected area according to the Birds Directive.
River Suldalslågen (Norway). (433kb) The River Suldaslågen is located in south-western Norway and represents a typical example for a river affected by hydropower generation in Norway. Within the catchment there are two large hydropower schemes, each with several reservoirs and power stations. Another typical feature is the transfer of water across catchment borders, which is diverted from other rivers to Suldaslågen increasing the catchment area from 1460 km2 to 2140 km2. Since Suldaslågen is one of the most famous Atlantic salmon rivers, the impact on salmon fisheries is of special concern. The case study focuses on the lower part of the river, a stretch of 22 km from the reservoir Lake Suldalsvatn to the sea.
River Beiarelva (Norway). (655kb) The River Beiarelva (50km) is situated in northern Norway at the margin of the second largest plateau-glacier (Svartisen) in a high mountainous area. Opposite to the case study Suldalslågen, this river is affected by diversion of water from its upper tributaries, resulting in a reduction of the catchment area from 859 km2 to 766 km2 and of discharge volume. The impacts result from hydropower production in an adjacent river and the case study is grouped into the subgroup "hydropower". Serious problems affecting the Atlantic salmon population arose from the infestation of the river by salmon parasites.
River Umealven (Sweden). (2.6MB) The River Umealven (450km) in northern Sweden was chosen as a case study since it is representative for the rivers that drain the Scandinavian mountain range and empty into the Gulf of Bothnia. Umealven is heavily affected by hydropower, but comparatively unaffected by other human activities, and therefore a good example to study the effects of hydropower. The hydropower stations (run-off river impoundments) use almost the entire fall height of the river, from the storage reservoir at 520 m a.s.l. to the sea. Reference conditions are preserved in the neighboured, still free flowing River Vindel with comparable size and hydrology.
River Emån (Sweden). (1.4MB) Emån is the largest river in south-eastern Sweden and is heavily affected by over fourty hydropower plants along its course. The study focuses mainly on the sub-catchment area of the short River Solgenån (23 km) in the northern part of the Emån catchment. In its basin, there are three large hydropower plants, hindering the migration of Salmo trutta. Other anthropogenic impacts are relatively insignificant. Land-use is mainly restricted to pasture and the surrounding vegetation consists predominantly of wetlands and coniferous forest in the upper stream.
Baltic Sea Coast (Sweden). (872kb) This case study was selected as an example for heavily modified waters in coastal areas up to 1 nautical mile of the main coast. The Stockholm Archipelago is one of the most complex parts of the Baltic Shore with over 24 000 islands, rocky islets and skerries. Small scale variations in landscape and ecosystems according to exposure, salinity, currents etc. characterise the study area. The area investigated comprises the southern part of Stockholm Archipelago and represents examples of more or less physically modified areas in coastal water environments. Main pressures are urbanisation, navigation and recreation, leading to physical modifications such as straightening of the shoreline, erosion protection, dredging and infrastructure along the shoreline.
River Dalalven (Sweden) (4.4MB) : The case study of the River Dalälven in Sweden has been focussed on the fish fauna and the specific problems caused by regulation and hydropower for fish, including the release of salmonid fish for compensation purposes. The river is highly affected by modifications due to approximately 500 dams and 39 hydropower plants. Regulation dams and constructions for hydroelectric power affect lakes and rivers in the drainage basin as well as the smaller streams. Ditching forests and mires, building road culverts, and log-driving channels and dams have profound effects for smaller streams in the catchment. Using variables obtained from geographical information of data on physical modification, indicator variables were tested against fish variables. Ecological status and potential was classified using expert judgement of hydromorphological alteration and necessary mitigation measures.
River Sankey Brook (UK). (588kb) Sankey Brook (127 km) is a tributary to the River Meuse, located east of Liverpool. It is representative of many rivers located in the industrial regions of the UK. Sankey Brook is subject to a mixture of pressures such as urbanisation, industry, flood defence and agricultural development. Impacts include land drainage, poor water quality and general degradation of instream and riparian habitats. Many physical modifications stem from historical industrial development, especially mining.
River Great Ouse (UK). (1.2MB) The Great Ouse catchment covers much of East Anglia and represents a heavily regulated lowland river. Much of it has been heavily engineered for flood defence and land drainage purposes as well as for navigation purposes. Modifications include completely artificial cut-off channels, channel re-alignment and re-sectioning, bank reinforcement, weirs/locks and loss of floodplain channel diversity. As a result of drainage, fens were transformed from wetland with raised islands of clay into some of the most productive arable land in the UK. Overall, despite the extensive human influence on the landscape, parts of the area have been designated as Special Protection Areas (SPA), Sites of Special Scientific Interest (SSSIs) and Ramsar sites.
River Tame (UK). (1.0MB) The Tame River Basin in central England is an example of a catchment with widely varying land use, river use, river modification and ecology. The main River Tame runs through heavily urbanised areas of Birmingham and represents an example of a degraded urban river with heavy urbanisation at the top of the catchment. Urbanisation has led to higher flood peaks as well as pollution which, combined with poor habitats, has led to poor ecological conditions. Some of the River Tame’s tributaries are less modified, and are good examples of degraded rivers with potential for rehabilitation.
Forth Estuary (UK). (5.2MB) This study represents the second case study for transitional waters. The Estuary and the River Firth of Forth together form a key segment of the east coast of Scotland, stretching from the centre of the country eastwards past Edinburgh to join the North Sea. Characteristic for this classic trumpet shaped estuary of about 45 km length, are high tidal ranges (up to 5m) and large areas of intertidal mud. The margins of the Forth Estuary are densely settled with four major urban settlements. Hence, main impacts are urbanisation, flood defence and loss of intertidal zones.
River Dee (UK). (3.26MB) The catchment of the River Dee (Galloway) is situated in the southern uplands of Scotland. Typical for this area is a wide network of streams and natural lakes. The area has a very low population density with about 0.23 persons per hectare with pasture and forestry as main land-use patterns. The principal pressure on the River Dee is hydro-power and hence this case study belongs to the hydropower sub-group. The Galloway hydropower scheme comprises a sequence of six hydropower stations with a total installed capacity of 109 MW.
River Tummel (UK). (4.2MB) The catchment of the River Tummel is located in the northern highlands of Scotland. It covers an area of 1,713 km2 and reaches a peak altitude of 1,083 m a.s.l. The Tummel study area has a very low population density (less than 0.10 persons per hectare). The single pressure in the River Tummel Basin is a large-scale hydro-power generation by a scheme of five hydropower stations and an extensive channel system to direct water from other catchments towards the stations. Habitat creation associated with some water bodies in the hydropower scheme area is of acknowledged nature conservation value. These parts of the water bodies have been designated as Sites of Special Scientific Interest.
River Lagan (UK). (601kb) The Lagan catchment is the most densely populated area in Northern Ireland including the city of Belfast. It drains some of the most productive agricultural lands in Northern Ireland. The estuary of Lagan (Belfast Lough) is characterised by the Belfast harbour and hence heavily changed and subject to dredging activities. The main pressure in the Lagan catchment is urbanisation in the lower catchment and physical modifications for industrial purposes, flood defence and navigation. A reinstatement of the Lagan canal system is under discussion. This study contributes to the navigation subgroup.
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