Revised Terms of Reference [28/11/2000]
Heavily Modified Waters in Europe Case Study on the River Ruhr
Research Project MAKEF Dr. P. Podraza University of Essen Institute of Ecology, Department of Hydrobiology 45117 Essen
Phone: 0049-(0)201-183-3868 Fax: 0049-(0)201-183-4583 Email: [email protected] Members of the research project MAKEF (co-authors)
• Dr. P. Podraza University of Essen Institute of Ecology, Department of Hydrobiology 45117 Essen
• Prof. Dr. Klaus Greve Rheinische Friedrich-Wilhelms-Universität Bonn, Geographic Institute, 53115 Bonn
• Martin Halle umweltbüro essen, A. Bolle & Partner GbR Rellinghauser Str. 334 f 45136 Essen
• Dr. Thomas Zumbroich, Dr. Andreas Müller Büro für Umweltanalytik Bonn/ Essen Breite Str. 21 53111 Bonn
• Dirk Glacer Ingenieurbüro Glacer Horster Str. 25e 45279 Essen
2 Table of Contents page PART I 4 1 Preface [to be drafted by project managers] 5 2 Summary Table 7 3 Introduction 9 3.1 Choice of Case Study 9 3.2 General Remarks 9 4 Description of Case Study Area 11 4.1 Geology, Topography and Hydrology 11 4.2 Socio-Economic, Geography, and Human Activities in the Catchment 13 4.3 Identification of Water Bodies 19 4.4 Discussion and Conclusions 21 PART II 24 5 Physical Alterations 25 5.1 Pressures and Uses 25 5.2 Physical Alterations 26 5.3 Changes in the Hydromorphological Characteristics of the Water Bodies and Assessment of Resulting Impacts 32 5.4 Discussion and Conclusions 32 6 Ecological Status 34 6.1 Biological Quality Elements 34 6.2 Physico-Chemical Elements 35 6.3 Definition of Current Ecological Status 36 6.4 Discussion and Conclusions 43 7 Identification and Designation of Water Bodies as Heavily Modified Fehler! Textmarke nicht definiert 7.1 Provisional identification of HMWB Fehler! Textmarke nicht definiert. 7.2 Necessary hydromorphological changes to achieve Good Ecological Status (GES) Fehler! Textmarke nicht definiert. 7.3 Assessment of Other Environmental Options Fehler! Textmarke nicht definiert. 7.3.1 Identification and definition of the beneficial objectives served by the modified characteristics of the water body Fehler! Textmarke nicht definiert. 7.3.2 Alternatives to the existing ”water use“ Fehler! Textmarke nicht definiert. 7.4 Designation of Heavily Modified Water BodiesFehler! Textmarke nicht definiert. 7.4.1 Identification of human benefit by achieving GESFehler! Textmarke nicht definiert. 7.4.2 Economic analysis of measures to achieve GESFehler! Textmarke nicht definiert. 7.4.3 Comparing the costs to achieve GES with the costs to achieve GEPFehler! Textmarke nicht 7.4.4 Designation of water bodies and objectivesFehler! Textmarke nicht definiert. 8 Definition of Maximum Ecological Potential 45 8.1 Determining Maximum Ecological Potential and Comparison with Comparable Water Body 75 9 Definition of Good Ecological Potential 77 9.1 Determination of Good Ecological Potential 77 PART III 79 10 Conclusions, Options and Recommendations 80 11 Bibliography 81
3 PART I
4 1 Preface [to be drafted by project managers] (1 page)
[insert the standard preface - drafted by the project managers - briefly explaining the European project on heavily modified water bodies as the context for the individual case study. This should explain the context to readers of the case study, who may not be familiar with the European project. ]
5
2 Summary Table (2 pages) Annex IV: Information on Case Studies (one Table for each Case Study)
Item Unit Information
1. Country text Germany 2. Name of the case study (name of water body) text Ruhr 3. Steering Committee member(s) responsible for the case text Dr. Ulrich Irmer, Dr. Bettina Rechenberg, German Federal study Environmental Agency (UBA) 4. Institution funding the case study text National Ministry for Education and Research (BMBF)
5. Institution carrying out the case study text University of Essen, University of Bonn, umweltbüro essen, Büro für Umweltanalytik, Büro Glacer 6. Start of the work on the case study Date 01.09.2001 7. Description of pressures & impacts expected by Date - 8. Estimated date for final results Date 31.03.2002
9. Type of Water (river, lake, AWB, freshwater) text River 10. Catchment area km2 4488 km² 11. Length/Size km/ km2 219.2 km (Ruhr); 5021 km (running water in the River Ruhr catchment) => Stream density in the catchment: 0.98 km/km² 12. Mean discharge/volume m3/s or m3 Mean discharge near mouth 1991-2000: 75.1 m³/s; mean discharge winter 2000: 132.1 m³/s; mean discharge summer 2000: 32.9 m³/s 13. Population in catchment number 2.2 Mio. 14. Population density Inh./km2 490 Inh. / km²
7 15. Modifications: Physical Pressures / Agricultural influences text Water abstraction for drinking water supply, cooling and industrial use 16. Impacts? text 14 reservoirs (volume: 473,6 Mio m³), 5 impounded lakes (volume: 19,1 Mio m³), 17 hydropower stations (162 Mio kWh/a), 89 wastewater treatment plants, 489 wastewater treatment and discharging units (e.g. CSO), 49 weirs in the middle and lower Ruhr 17. Problems? text Eutrophication (algal blooms) in the lower Ruhr, local oxygen depression in summer, local critical free ammonia concentration (NH3) in spring, local heavy metal pollution of river sediments, disruption of river continuum and sediment transport. smoothing of flow dynamics.
18. Environmental Pressures? text Urbanisation along the middle and lower Ruhr (one of Germany's biggest industrial centre: Ruhrgebiet), agriculture and forestry in the catchment of the upper and middle Ruhr, recreation (e.g. shipping, fishing) 19. What actions/alterations are planned? text - Restoration measures/habitat improvement - Enhanced Wastewater Treatment - Construction of fish pathways - Establishment of buffer strips. 20. Additional Information text
21. What information / data is available? text - land use patterns - data on water chemistry and discharge - survey on treatment and discharge of wastewater (e.g. wastewater treatment plants, combined sewer overflows (CSO)) - German Water Quality Survey, - German River Habitat Survey, - inventories of fish and benthic invertebrate fauna 22. What type of sub-group would you find helpful? text 23. Additional Comments text
8 3 Introduction (2 pages)
3.1 Choice of Case Study
The River Ruhr was chosen as a case study object for several reasons: • The River Ruhr is located in Northrhine-Westfalia, a German state with well defined reference water courses (reference conditions on water quality, hydrology, stream morphology, macroinvertebrates, fish, vegetation). So the natural scale for assessing stream quality is available. • The catchment of the River Ruhr represents several different stream types in different landscape areas (= different reference conditions). • The River Ruhr represents rivers in highly industrialised areas. The multiplicity of different pressures and impacts increases the probability of a designation as heavily modified waterbody. • The water management association “Ruhrverband” surveys water quality and manages the discharge of the river Ruhr. Thus, detailed data on these subjects are available over long periods of time and were kindly provided to be used for the case study. • The Department for Hydrobiology at the University of Essen (Dr. Daniel Hering) is coordinating another EU-research project on the implementation of the EU WFD "The Development and Testing of an Integrated Assessment System for the Ecological Quality of Streams and Rivers throughout Europe using Benthic Macroinvertebrates (Acronym: AQEM)". This project targets is towards the development an assessment procedure for the ecological quality of streams and rivers in Europe. So for this case study on heavily modified water bodies also a river was chosen, to apply this new AQEM procedure, defining the ecological status. • This case study is carried out as a part of a three years research project financed by the German Department of Research and Development, “MAKEF”, on the development of methods and tools for the designation of heavily modified water bodies in the catchment areas of Ruhr and Mulde.
3.2 General Remarks
The River Ruhr, a tributary of the River Rhine, is situated in the midwestern part of Germany with a stream length of 219.2 km. The major part of the Ruhr catchment is part of ecoregion 9 (central highlands), while the mouth and the north western tributaries belong to ecoregion 14 (central plains). (see map 3.2.-1 for the location in the ecoregions). The "Ruhrgebiet" located in the western part of the River Ruhr catchment is one of the largest and densest industrial centres in Europe. In the 18th and 19th century cities like Bochum, Essen, Mülheim, and Duisburg developed along the River Ruhr as a consequence of coal mining and steel production. While about 2.2 million people inhabit the Ruhr catchment, the water of the River Ruhr serves as a water supply for 5.2 million people, with the consequence of a water transfer of about 300 Mio. m³/a to the catchments of the rivers Emscher, Lippe, Wupper, and Ems. Map 3.2-1 Catchment of the River Ruhr in the system of ecoregions
9 In the eastern part of the catchment agriculture and forestry form the dominating land uses. 14 reservoirs with a total volume of 473.6 million m³ were built in this area to regulate the flow and to guarantee a sufficient water quantity even under low flow conditions,. Due to organisational reasons (assignment of this research project to an EU-HMW subgroup) the main impact factor on the ecological quality of the Ruhr River had to be chosen preliminarily: the supply of drinking water for 5.2 million inhabitants and the water supply for industrial use. In consequence the case study on the River Ruhr is assigned to the impact group "water supply" with dams, interrupted longitudinal continuum and modified high and low flow conditions. Together with the impact group "hydro-power generation" this impact group forms the EU-HMW subgroup No. 1. (In fact, the dams and weirs in the River Ruhr are used for hydro-power generation as well, producing 162 million kW/a). EU-HMW subgroup No. 2 consists of the impact groups navigation, flood protection, and agricultural pressures. The pressures and impacts discussed there are also relevant for the case study River Ruhr, with the reservoirs being used for flood protection of the downstream areas and with 76 km of the River Ruhr being assigned for navigation purposes.
10 4 Description of Case Study Area (3 pages)
4.1 Geology, Topography and Hydrology
Northrhine-Westfalia, belonging to ecoregion 14 and 9, is divided into 10 subregions with 23 stream and river types. The catchment area of the River Ruhr (4488 km²) is part of 5 subregions with 8 different stream and river types (Map + Fig. 4.1.-3). The major part of the catchment is characterized by siliceous geology (Map 4.1.-1), dominated by metamorphic crystalline (slate) and volcanic rock (landscape subregion: siliceous basement rocks, Geology: mainly Devon and Perm). Due to this geology a siliceous soil type (brown earth = Braunerde) was formed, which dominates the catchment. In the floodplains the soil is rather fertile with soil type Pseudogley, Gley and pasture soil (Map.4.1.-2). Into this landscape subregion areas with limestone karsts are embedded, originating from fossil coral reefs built in Creatacenous ("Kreide"). In the mountainous section of the River Ruhr the mean slope amounts to about ≈ 40 ‰. The middle and lower section of the River Ruhr has a wide fluvial valley, filled with sandy and gravel deposits. The mean slope of the north western tributaries is rather low (mean slope ≈ 6 ‰) with loess and loam dominating the stream bed substrates. The mouth region of the Ruhr enters the plains formed by the River Rhine, which are characterized by gravel deposits. Tributaries in this region may be boggy under natural conditions.
Map 4.1.-1 Geology in the catchment of the River Ruhr
11 Map 4.1.-2 Soils in the catchment of the River Ruhr
The source of the River Ruhr is located appr. 670 m above sea level, the mouth appr. 19 m above sea level. The length of the River Ruhr measures 219.2 km, with 5021 km in total for all rivers and streams in the Ruhr basin. Mean discharge (1991-2000) at the River Ruhr mouth is 75.1 m³/s; with a mean discharge in winter (winter 2000) of 132.1 m³/s and a mean discharge in summer (summer 2000) of 32.9 m³/s.
12 Map 4.1.-3 Typology of the River Ruhr and its tributaries
Stream Typologie in the catchment of the River Ruhr Stream Typologie River Ruhr Mid-sized gravel bottom mountain river (basement rocks)
Large mountain stream in floodplain valley Mid-sized gravel bottom (basement rocks) mountain river (basement rocks) Small mountain stream in floodplain valley (basement rocks)
Mountain gully on basement rocks Large mountain stream in floodplain valley Organic brook (basement rocks)
Small karst stream
Small mountain stream Small floodplain streams in floodplain valley (basement rocks) Small loess-loam bottom streams
0 50 100 150 200 250 0 500 1.000 1.500 2.000 2.500 Fließlänge [km] Fließlänge [km]
Fig. 4.1.-1: Distribution of stream types for the River Ruhr and for the sum of streams and rivers in the catchment...
The precipitation in the basin of the River Ruhr is rather high due to the landscape morphology with a mean annual precipitation of 1051 mm (average 1927-1999). Due to the high rainfall intensity and the low water storage capacity of soil and geology the stream density in the catchment amounts to 0.98 km/km², a relatively high value.
4.2 Socio-Economic, Geography, and Human Activities in the Catchment
Depending on the different intensities of modifying the annual discharge of the River Ruhr, for the purpose of this case study three different sections (management units) of the river can be separated (Map 4.2.-1).
13 Map 4.2.-1: The management units 'Lower Ruhr River', 'Middle Ruhr River', and 'Lower Ruhr River' and some main tributaries in the catchment In the upstream region of the River Ruhr (182.3 km – km 219.2) the discharge is not influenced by reservoirs. The annual flow dynamic is more or less natural and only influenced by human modifications of land use. The discharge of the middle Ruhr River (km 92.7 – km 182.3) is modified by 14 reservoirs, smoothing the natural flow dynamic by depressing high flow conditions and mitigating low flow conditions, adding water from the reservoirs (see 5.2). At the lower Ruhr River (km 0 (mouth) - km 92.7) 5 impounded lakes, in former time built to accelerate self-purification ("self-purification reactors"), now mainly used for drinking water supply and recreation, increases the retention time of the river. The stream looses most of his character as running water, promoting algal blooms. In the mouth region the biggest inland harbour of the world (Duisburg) is situated with 1.39 km² harbour basins, designated as "artificial water bodies". The River Ruhr passes the harbour area in the south (4.15 km) with a connection to the harbour basins, but the main entrances to the harbour are situated at the right shoreline of the River Rhine. The population of the catchment amounts to 2.2 million inhabitants, concentrated in the industrial centre "Ruhrgebiet" at the lower Ruhr River, especially in the cities Bochum, Essen, Mülheim, and Duisburg. The water of the River Ruhr serves for the water supply of 5.2 million people with the consequence of water transfer to other catchments (rivers Emscher, Lippe, Wupper, and Ems). The total annual water abstraction for water supply amounts to appr. 600 million m³/a with a transfer of 300 m³/a to other catchments. To treat the wastewater produced, 101 wastewater treatment plants, and 377 wastewater treatment and discharging units (e.g. combined sewer overflows - CSO) were built in the catchment (Fig. 4.2.-1)
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Fig. 4.2-1 Wastewater treatment plants and combined sewer overflows (CSO) in the catchment of the River Ruhr (from: Ministerium für Umwelt und Naturschutz, Landwirtschaft und Verbraucherschutz NRW [Hrsg.] (1999))
Saprobic Status River Ruhr 90 80 70 60 50 40 30 Percentage [%] 20 10 0 I I-II II II-III III III-IV IV
Fig. 4.2-2 Distribution of saprobic status (water quality survey) in the River Ruhr in 1999.
In spite of the number of point sources of organic pollution (e.g. wastewater treatment plants, combined sewer overflows; Fig 4.2.-1) at the River Ruhr and its tributaries (mean COD- discharge in the Ruhr catchment: 15,313 t COD p. a.) the water quality of the River Ruhr does not show any severe saprobic pollution (Fig. 4.2.-2). (The assessment of the saprobic status (= indication of organic pollution) employs the standardised procedure for water quality survey in Germany. The saprobic status is ranked in seven classes from very low organic concentrations (oligosaprob = blue colour) – to high concentrations (polysaprob = red colour). A sufficiently high water quality status is indicated by a bright green colour.) Only at the lower
15 Ruhr River, the water quality is slightly stronger polluted than saprobic class II due to secondary effects of algal blooms in the impounded lakes.
16 Tab.4.2.-1: Water Quality Parameters in the River Ruhr (+Mouth of Tributaries). Comparison Year 1966 – Year 2000 max. pH Conductivity NO -N NO -N NH -N o-PO -P SO 3 2 4 4 4 Chlorophyll-a [µS/cm] [mg/l] [mg/l] [mg/l] [mg/l] [mg/l] µg/l lfd. Station 1966 2000 1966 2000 1966 2000 1966 2000 1966 2000 1966 2000 1966 2000 2000 Nr.
1 oberh. Wildshsn. 7.7 7.90 230 307 2.03 3.00 0.05 0.060 0.21 <0.010.16 0.01 33.0 33.0 2 Br.-B7 Oeventrop 8.1 7.80 280 343 2.03 3.00 0.07 0.070 0.26 <0.010.13 0.02 44.0 39.0 3 Wolfsschl.Arnsb. 7.9 7.80 290 340 1.81 2.90 0.07 0.080 0.26 <0.010.12 0.02 40.0 39.0 4 oberh. Klg. Hüsten 7.9 8.00 270 349 2.03 2.90 0.10 0.060 0.40 0.02 0.24 0.01 44.0 42.0 5 Röhr Mündung 7.8 8.00 220 394 1.81 3.70 0.07 0.160 0.29 0.43 0.05 0.01 39.0 45.0 6 oberh. Zul. Möhne 7.6 8.00 270 358 1.81 3.10 0.09 0.060 0.44 0.01 0.16 0.01 46.0 43.0 7 Möhne Mündung 7.9 8.40 260 338 1.13 2.50 0.01 0.030 0.02 0.02 0.02 <0.01 31.0 30.0 8 Echthausen-OW 7.7 8.00 280 374 1.35 3.30 0.05 0.070 0.24 0.07 0.11 0.01 41.0 42.0 7.1 WW Hamm- 9 Warmen 7.6 8.00 270 377 1.58 3.20 0.09 0.070 0.30 0.21 0.13 0.01 40.0 43.0 9.8 10 Hönne Mündung 7.7 8.20 460 669 2.48 5.30 0.13 0.100 1.16 0.01 0.18 0.02 61.0 60.0 11 Halingen AWWR 7.6 7.60 330 450 1.58 3.70 0.13 0.100 0.73 0.36 0.14 0.02 53.0 49.0 6.6 12 Baarbach Mündung 7.7 7.80 570 1330 1.35 3.10 0.23 0.400 6.58 19.00 1.21 0.10 110.0 160.0 Wellenbad 13 Geisecke 7.6 7.80 310 472 1.81 3.70 0.13 0.130 0.66 1.10 0.13 0.02 51.0 52.0 14 Kraftw.Westhofen 7.6 7.80 300 469 1.58 4.00 0.16 0.150 0.58 0.51 0.19 0.02 53.0 53.0 14.1 15 Lennebr. Mündung 7.3 8.00 260 411 1.81 2.80 0.08 0.040 0.63 0.95 0.06 0.01 81.0 48.0 16 Ausl. Hengsteysee 7.5 7.90 280 446 1.35 3.00 0.12 0.110 0.76 0.56 0.12 0.01 69.0 54.0 24.3 17 Volme Mündung 7.8 8.30 300 376 3.16 3.80 0.25 0.060 0.65 0.05 0.52 0.03 69.0 52.0 18 Pegel Wetter 7.3 8.10 310 451 1.81 3.60 0.16 0.110 1.07 0.32 0.27 0.01 74.0 56.0 19 WW Witten Gels. 7.4 8.10 300 451 1.81 3.60 0.14 0.100 0.75 0.08 0.18 0.01 59.0 56.0 142.7 20 Einl. Kemnader See 7.2 8.00 330 492 2.71 4.20 0.15 0.130 0.61 0.06 0.30 <0.01 63.0 66.0 21 Ölbach 7.7 7.40 5000 2780 0.90 2.60 0.51 0.180 14.78 0.10 3.59 0.20 317.0 150.0 22 PW. Steele-Horst 7.3 8.00 510 542 2.94 3.50 0.17 0.080 0.40 0.09 0.27 <0.01 95.0 68.0 23 Essen-Rellinghsn. 7.4 7.90 520 553 3.16 3.60 0.17 0.080 0.44 0.11 0.36 <0.01 95.0 69.0 166.0 24 Einl. Baldeneysee 7.2 7.90 730 583 2.94 5.10 0.22 0.080 0.61 0.15 0.46 <0.01101.0 73.0 25 Ausl. Baldeneysee 7.4 7.90 550 620 2.71 3.20 0.19 0.080 0.93 0.25 0.21 <0.01 97.0 75.0 26 Ausl. Kettwig.See 7.2 7.90 550 585 2.48 4.00 0.21 0.100 1.01 0.40 0.13 0.01 103.0 73.0 13.4 27 WW. Styrum-Ost 7.4 7.70 560 570 2.94 3.30 0.22 0.100 1.16 0.43 0.22 <0.01108.0 72.0 21.0 28 Duisb. Ackerfähre 7.3 7.80 590 571 2.71 3.30 0.23 0.100 0.98 0.32 0.22 <0.01108.0 73.0
17 Tab.4.2.-1 (continued): Water Quality Parameters in the River Ruhr (+Mouth of Tributaries). Comparison Year 1966 – Year 2000 Cl Fe Mn Pb Cu Ni Zn Cr [mg/l] [mg/l] [µg/l] [µg/l] [µg/l] [µg/l] [µg/l] [µg/l] lfd. Probestelle 1966 2000 1966 2000 1966 2000 1966 2000 1966 2000 1966 2000 1966 2000 1966 2000 Nr.
1 oberh. Wildshsn. 17.0 17.0 0.51 0.03 40.0 13.0 < 10.0 0.35 < 10.0 1.10 < 10.0 1.1 80.0 49.0 10.0 <1.0 2 Br.-B7 Oeventrop 22.0 19.0 0.78 0.04 100.0 21.0 310.0 0.54 10.0 1.70 < 10.0 1.3 110.0 48.0 40.0 <1.0 3 Wolfsschl.Arnsb. 24.0 19.0 0.78 0.04 110.0 21.0 230.0 0.49 < 10.0 1.70 < 10.0 1.3 110.0 54.0 20.0 <1.0 4 oberh. Klg. Hüsten 23.0 20.0 0.82 0.05 20.0 19.0 170.0 0.64 10.0 2.20 < 10.0 1.6 90.0 46.0 20.0 <1.0 5 Röhr Mündung 13.0 19.0 0.51 0.13 30.0 29.0 30.0 0.86 40.0 3.00 20.0 8.9 100.0 8.7 20.0 2.3 6 oberh. Zul. Möhne 21.0 20.0 0.51 0.06 410.0 19.0 80.0 0.75 < 10.0 2.40 < 10.0 2.6 100.0 39.0 20.0 <1.0 7 Möhne Mündung 33.0 31.0 0.78 0.06 40.0 21.0 < 10.0 0.22 10.0 2.00 10.0 2.8 100.0 2.8 20.0 <1.0 8 Echthausen-OW 25.0 25.0 0.19 0.05 20.0 31.0 20.0 0.80 10.0 2.30 10.0 2.9 30.0 26.0 20.0 <1.0 WW Hamm- 9 Warmen 23.0 26.0 0.23 0.10 110.0 27.0 30.0 0.83 < 10.0 2.80 10.0 3.5 20.0 26.0 20.0 <1.0 10 Hönne Mündung 45.0 69.0 0.70 0.02 190.0 19.0 < 10.0 0.27 150.0 3.20 90.0 4.4 460.0 10.0 40.0 1.4 11 Halingen AWWR 29.0 37.0 0.39 0.07 110.0 26.0 20.0 0.30 50.0 2.50 30.0 3.6 110.0 21.0 40.0 1.1 12 Baarbach Mündung 39.0 160.0 3.74 0.77 170.0 150.0 < 10.0 3.30 270.0 16.00 210.0 28.0 400.0 56.0 30.0 6.6 Wellenbad 13 Geisecke 26.0 39.0 0.35 0.15 110.0 61.0 < 10.0 1.50 60.0 3.90 30.0 4.9 90.0 25.0 10.0 1.2 14 Kraftw.Westhofen 27.0 38.0 0.51 0.09 40.0 42.0 10.0 0.76 50.0 3.00 60.0 4.2 70.0 20.0 30.0 <1.0 15 Lennebr. Mündung 20.0 39.0 1.56 0.80 220.0 29.0 10.0 1.40 90.0 5.30 70.0 4.2 810.0 30.0 20.0 1.9 16 Ausl. Hengsteysee 21.0 39.0 1.13 0.19 50.0 120.0 10.0 1.60 30.0 5.70 20.0 5.7 260.0 30.0 60.0 1.4 17 Volme Mündung 27.0 30.0 1.01 0.18 40.0 33.0 < 10.0 2.70 50.0 6.40 80.0 5.1 190.0 19.0 30.0 1.3 18 Pegel Wetter 25.0 40.0 0.97 0.14 190.0 77.0 < 10.0 1.50 20.0 6.40 40.0 6.1 230.0 30.0 20.0 1.5 19 WW Witten Gels. 24.0 39.0 0.66 0.15 90.0 77.0 < 10.0 1.60 10.0 7.10 30.0 6.2 190.0 23.0 20.0 1.6 20 Einl. Kemnader See 26.0 45.0 0.51 0.20 30.0 71.0 < 10.0 0.67 10.0 6.80 40.0 7.7 230.0 28.0 20.0 1.3 21 Ölbach 1560.0 600.0 0.93 0.46 10.0 180.0 30.0 0.27 10.0 7.60 100.0 5.7 150.0 8.3 20.0 2.4 22 PW. Steele-Horst 59.0 55.0 0.70 0.14 90.0 63.0 < 10.0 1.10 60.0 6.70 30.0 6.1 110.0 27.0 30.0 1.1 23 Essen-Rellinghsn. 62.0 57.0 0.58 0.17 140.0 62.0 < 10.0 1.00 10.0 6.60 30.0 6.2 80.0 24.0 10.0 1.0 24 Einl. Baldeneysee 129.0 59.0 0.39 0.18 160.0 100.0 < 10.0 0.61 10.0 6.60 30.0 6.3 90.0 23.0 10.0 <1.0 25 Ausl. Baldeneysee 74.0 70.0 0.35 0.23 170.0 81.0 10.0 1.60 20.0 5.50 40.0 6.4 60.0 17.0 20.0 <1.0 26 Ausl. Kettwig.See 72.0 63.0 0.31 0.18 200.0 85.0 < 10.0 1.40 10.0 5.40 40.0 6.6 80.0 18.0 10.0 <1.0 27 WW. Styrum-Ost 74.0 59.0 0.19 0.11 30.0 64.0 10.0 0.90 20.0 5.30 40.0 6.3 50.0 16.0 10.0 <1.0 28 Duisb. Ackerfähre 80.0 59.0 0.19 0.15 180.0 72.0 10.0 1.50 10.0 6.00 40.0 6.6 70.0 20.0 10.0 <1.0
18 Table 4.2.-1 shows the reduction in nutrient concentration (e.g. NH4-N and dissolved PO4-P) compared to the situation in 1966. Despite this reduction, algal blooms - indicated by high chlorophyll-a concentrations - still occur in the impounded lakes and downstream (resulting from downstream transport of phytoplankton). The heavy metal concentration was reduced 2- - as well, but conductivity as well as concentrations both of SO4 and Cl increase due to the discharge of abandoned coal mines.
4.3 Identification of Water Bodies
The River Ruhr belongs to the surface water category "river". It has been subdivided into three effective management units (see 4.2), based on the different intensities of • annual discharge regime modification • water abstraction for water supply • volume of impounded water Each management unit is subdivided into water bodies, which consist of several "subbodies", defined following the suggested scaling in 4.4.
Table 4.3.-1: Description of the River Ruhr Basin according to system A, WFD Annex II, 1.2. “Ecoregions and surface water body types”, expanded by optional factor according to system B (modified). Fixed Typology Descriptors Ecoregion Central highlands, central plains (Annex XI) Type Altitude typology: mid-altitude to lowland Size typology based on catchment area large > 1000 to 10000 km2 (4488 km²) Geology mainly siliceous with small calcareous areas and an organic patch near the mouth Optional Factors River Ruhr length: 219,2 km Management unit "Upper Ruhr River" Stream type: - Small mountain stream in floodplain valley (basement rocks) 9.6 km) Large mountain stream in floodplain valley (basement rocks) (10.2 km) Mid-sized gravel bottom mountain river (basement rocks) (17.1 km) Length: 36,9 km water width: 5 – 10 m water depth: < 0.10 – 1.00 m mean water slope: 11.3 ‰ form and shape of main river bed: curved to meandering channel with riffles and pools, sometimes branched river discharge: dry weather flow: ≈ 400 l/s valley shape: trough total hardness: 0.5 – 0.9 mmol/l: case study Ruhr 19 mean substratum composition: micro – mesolithal: 2 – 20 cm, + woody debris chloride: 9 – 15 mg/l Management unit "Middle Ruhr River " Length: 89.6 km Stream type: Mid-sized gravel bottom mountain river (basement rocks) water width: 20-40 m water depth: 0.50 -1 m mean water slope: 2.6 ‰ form and shape of main river bed: slightly curved and branched river discharge: 36.2 m³/s (mean 1999, gauging station Villigst) valley shape: floodplains flat with steep sides acid neutralising capacity: 0.5 – 0.83 mmol/l total hardness: 1.3 mmol/l mean substratum composition: micro – mesolithal: 2 – 10 cm + woody debris chloride: 12 – 21 mg/l water temperature range: 7.1 – 17.5 °C Management unit "Lower Ruhr River " Length: 92.7 km Stream type: Mid-sized gravel bottom mountain river (basement rocks) water width: 30 – 60 m water depth: 1 – 3 m mean water slope: 2.3 ‰ form and shape of main river bed: slightly curved and branched river discharge 92.7 m³/s (mean 1999, gauging station Mülheim) valley shape: Floodplains flat with steep sides, meander valley acid neutralising capacity: 0.91 mmol/l total hardness: 1.3 - 1.4 mmol/l mean substratum composition: microlithal: 1-2 cm + woody debris chloride: 27 – 60 mg/l water temperature range: 5.8 – 22.5 °C
The core region of the case study on the river Ruhr (Lower Ruhr River km 51.1 – km 92.9) can be separated into two different water bodies: waterbody 1 = mainly free flowing and waterbody 2 = mainly impounded (Map. 4.3-1).
case study Ruhr 20 30
25 impounded lakes stagnant upstream weir free flowing 20
15 km
10
5
0 Waterbody 1 Waterbody 2
Map 4.3.-1 Definition of water bodies and subbodies in the core region of the case study River Ruhr (Lower Ruhr River) and distribution of different hydrological conditions.
Waterbody 1 is subdivided into five subbodies with 8.9 km free flowing river and 3.3 km stagnant water upstream weirs. Waterbody 2 consists of eight subbodies, 7.9 km free flowing water, 5.6 km stagnant water upstream weirs and 14.1 km impounded lakes.
4.4 Discussion and Conclusions
Using the proposed fixed scaling of HMW paper 5 ver 3 (10 km stream length for investigations on the impact of human uses when the catchment is bigger than 1000 km², see map 4.4-1) at the lower Ruhr River, impounded and free flowing sections would be summarized to one waterbody (e.g. between km 60 – 70, km 90 – 100).
case study Ruhr 21 Map 4.4.-1 10 km-scaling, defining water bodies of the River Ruhr
If these sections were to be identified as hmw, then the closest comparable natural waterbody would be a natural lake (hmw paper 12 ver 3.3) with the consequence that for the actually free flowing section of the waterbody the good ecological potential would be described by a stillwater biocoenosis of a shallow lake. To solve this problem, we suggest to define the dimension of a waterbody by the length of the dominant pressure, aggregating similar stretches (= subbodies), as it was done in Map 4.3-1. If the conditions of a waterbody are not homogeneous, this waterbody should be divided into subbodies characterized by homogeneity of pressures. The assessment of the waterbody should be done in a representative section with the dominant human impact (e.g. in waterbody 1 the free flowing section should be assessed, in waterbody 2 the impounded lake section has to be assessed). In contrast, the subbodies are characterized by a more or less homogeneity of human pressures and therefore also by homogeneity of adverse effects upon uses by achieving the GES. Measures to improve the ecological status or ecological potential have to focus on the "critical" subbodies, because these are able to degrade the ecological status / potential of the whole waterbody (e.g. although the assessment of waterbody 1 should be done in subbody 1 b or 1 d, the measures to achieve a good ecological status should focus on subbody 1a, 1c and 1e) Defining the homogenous subbodies we suggest the following procedure: • If the catchment is of size < 1 000 km² and if the morphologically modified stream section (e.g. reservoir, impounded lake, canalization) extends over more than 0.1 km, then the morphologically modified stream section is identified as a single subbody (max. length = 1 km), beginning with the upper limit of the morphological modification (homogeneity of case study Ruhr 22 pressures in the subbody). • If the catchment is of size < 1 000 km² and if the morphologically modified stream section (e.g. small impounded lake, canalization) extends over less than 0.1 km, then a section of length 1 km is identified as a natural waterbody (heterogeneity of pressures in the subbody due to generalisation effects). • If the catchment is of size ≥ 1 000 km² and if the morphologically modified steam section extends over more then 1 km, then the morphologically modified stream section is identified as a single subbody (max. length = 10 km), beginning with the upper limit of the morphological modification (homogeneity of pressures in the subbody). • If the catchment is of size ≥ 1000 km² and if the morphologically modified stream section extends over less than 1 km, then a section of length 10 km is identified as a subbody (heterogeneity of pressures in the subbody due to generalisation effects). • Table 4.4.-1: Applied method of identifying subbodies in the case study on the River Ruhr Size of Catchment Area Length of morphologically Length of stream section, identified modified stream section as single subbody < 1,000 km² ≥ 0.1 km Length of morphologically modified stream section, max length = 1 km < 1,000 km² < 0.1 km 1 km ≥ 1,000 km² ≥ 1 km Length of morphologically modified stream section, max. length = 10 km ≥ 1,000 km² < 1 km 10 km
This way of scaling subbodies was used in the case study River Ruhr.
case study Ruhr 23 PART II
case study Ruhr 24 5 Physical Alterations (5 pages)
5.1 Pressures and Uses
Since the Middle Ages the River Ruhr has been influenced by human activities. Mills with weirs were built along the river and its tributaries. The forests within the catchment area were cleared, causing accelerated erosion with siltation of the meadows. The river was straightened with cutting off oxbows to use the valley for agriculture (=> fertile soils). The longitudinal straightening caused an increase in stream flow velocity with the consequence of deepening of the river bed. The stream type of a flat, branched, gravel dominated river changed to a more narrow as well as deeper river, which was also used for navigation. In 1780 in the research area 16 sluices were in use, with two of them still operating today. In the beginning of the 19th century the River Ruhr was the most frequently navigated river in the whole of Europe. In the year 1874 commercial navigation (transport of coal and steel) came to a sudden end with the completion of the “Ruhr Valley Railroad”. With the upcoming coal mining industry in the "Ruhrgebiet" in the 19th century the amount of wastewater increased as well. In order to solve the waste water problems the first impounded lake "Hengsteysee" was built in 1929 to accelerate self-purification by slowing down the flow. Between 1931 and 1950 three other impounded lakes were built to work as natural wastewater treatment plants. The last impounded lake (Kemnader Stausee) was built in 1979 for recreational purposes. The impact of water supply for 5.2 million inhabitants was already discussed in chap. 4.2. The annual water abstraction of 16.72 m³/s is more than twice as high as the mean low flow discharge of 7.05 m³/s (gauging station Mülheim, near to mouth). Based upon table "Overview of the main physical impacts on water bodies" (taken from hmw paper 5 ver.3) tab. 5.1.-1 and 5.1.-2 show the physical alterations and pressures in the three management units of the River Ruhr ranked by intensity, resp. significance of impact. Tab. 5.1.-1: Overview of the main physical impacts on water bodies (table modified and completed) (-: no relevance,!: low relevance, ": moderate relevance, #: high relevance)
Upper Ruhr River Middle Ruhr Lower Ruhr River River Physical Alterations Change in river profile """" # Disruption in river continuum & - " # sediment transport Channel maintenance/dredging/ !!!!!"" removal of material Channelisation/straightening """"""" Bank reinforcement/fixation/ """"""" Embankments Detach ox-bow lakes/wetlands !!""""" case study Ruhr 25 Restriction of flood plain """"""" Other Impacts Low flows - " (local) " (local) Anthropogenic peak flows --- Reduced velocity / stagnant water - " (local) # Direct damage to fauna/flora --- Artificial discharge regime - #### Land drainage ! -- Soil erosion/silting - !!""
Tab. 5.1.-2: Overview of the main pressures on the River Ruhr (-: no relevance,!: low relevance, ": moderate relevance, #: high relevance)
Pressures Upper Ruhr River Middle Ruhr River Lower Ruhr River
Navigation --! (76 km) Flood Protection !!""""" Hydro power generation """" Agriculture / Forestry !!!!!!! Water supply - " (6.02 m3/s) # (10.7 m³/s) Urbanisation/ Recreation ! (local) " (local) #
5.2 Physical Alterations
The assessment of the morphological status of the River Ruhr and its main tributaries illustrates the physical/morphological alterations caused by the pressures listed in Table 5.1.- 2. . The morphological structure was evaluated by the standardized procedure for stream habitat survey in Germany with the morphological status being ranked in seven classes from “pristine” (= blue colour) to “extremely modified” (= red colour). A good morphological status is indicated by a bright green colour. The results can be aggregated to an overall-evaluation or they can be visualized separately for morphological sub indices like, e.g., Channel Form, Bank Protection, or Streambed Structure The assessment of the overall-evaluation of the River Ruhr basin shown in Map 5.2.-1 illustrates the morphological deficits.
case study Ruhr 26 Map 5.2.-1 Overall-evaluation of the morphological status in the River Ruhr basin (grey area) The distribution of morphological status classes of the sub indices "channel form" and "streambed structure" are shown in Fig. 5.2.-1. It can be found that both parameters correlate fairly – the corresponding diagrams bear clear similarities for all river sections. The frequency distributions appear to be “normal”, with a wider spread in the Upper Ruhr region, a shift to worse morphological status in the Middle Ruhr and just three different classes (4 to 6) in the Lower Ruhr. The mouth region, which is influenced by the harbour area, was assessed to be of bad morphological status (class 7, overall evaluation) due to the dominance of fixed banks (locally metal pealing walls), moorings on the right and left embankments, and loading ramps for petrol products.
Channel Form Upper Ruhr Streambed Structure Upper Ruhr
45 60
40 50 35 30 40
25 30 20 15 20
Percentage[%] 10 10
5 Percentage [%] 0 0 1234567 1234567 Quality class Quality class case study Ruhr 27 Channel Form Middle Ruhr Streambed Structure Middle Ruhr 35 40 30 35 30 25 25 20 20 15 15 10 10 5 5 Percentage [%] Percentage [%] 0 0 1234567 Quality class 1234567 Quality class
Channel Form Lower Ruhr Streambed Structure Lower Ruhr
50 60 45 50 40 35 40 30 25 30 20 20 15
Percentage [%] 10 10
5 Percentage[%] 0 0 12345678 1234567 Quality class Quality class
Fig. 5.2.-1 Share of morphological status classes (stream habitat survey) in the River Ruhr
Table 5.2.-1 shows the dimensions of the five impounded lakes of the lower Ruhr River. In this lakes the stream velocity is rather low to stagnant with a mean residence time e.g. in the "Baldeneysee" of 27 hours (90 hours in low flow periods).
Tab. 5.2.-1 Dimensions of the 5 impounded lakes of the lower Ruhr River
Impounded Lake Volume Surface area Length Ø Width Ø Depth Hengsteysee 3.3 Mio. m³ 1.36 km² 4.2 km 296 m 1.94 m Harkortsee 3.1 Mio. m³ 1.37 km 3.2 km 335 m 2.21 m Kemnader See 3.0 Mio. m³ 1.25 km² 3.0 km 420 m 2.40 m Baldeneysee 8.3 Mio. m³ 2.64 km² 7.8 km 355 m 3.14 m Kettwiger See 1.4 Mio. m³ 0.55 km² 5.2 km 130 m 2.54 m
case study Ruhr 28 © Ruhrverband 2001
case study Ruhr 29 Location of Weirs, and Discharge at the Gauging Stations of the Middle and Lower Ruhr
Fig. 5.2.-3 Location of Weirs, and Discharge at the 8 Gauging Stations of the Middle and Lower Ruhr River, 04.Oct. 2001 Along the River Ruhr 49 weirs were built for purposes of hydropower generation, navigation and discharge regulation. Not all weirs can be passed by migrating fish. Although 47 weirs are equipped with fish passes, either already existing or to be realised in the near future, at least some of the already existing fish ladders do not work properly. The level of the weirs amounts from less than 1 m up to 8.65 m (Fig. 5.2.-4). These differences in water level can't be passed by most of the migrating fish species without fish pass or fish ladder.
case study Ruhr 30 20 18 16
i 14 12 10 8
Number of we of Number 6 4 2 0 < 2< 4< 6> 6 Dam Height [m]
Fig. 5.2.-4 Distribution of dam height in 49 weirs along the River Ruhr
Land Utilization
20
15
10
5
Percentage [%] Percentage 0 Fallow Pasture Housing Railways Water Supply Water Forest, Wood Forest, Energy Supply Gardening other Buildings Lawn and Parks former Traffic Area Traffic former Trade and IndustryTrade and Fields, Commercial Streets, Parking places
Fig. 5.2.-5 Land utilization in the lower Ruhr Valley
Regarding the lower Ruhr River, the water bodies are mainly influenced by the impounded lakes, which are now used as reservoirs for water abstraction to produce drinking water and for recreational purposes (sailing, wind surfing, rowing, canoeing, passenger navigation, and intensive use of the lake shores for hiking, cycling and inline skating), which is in fact their main function. Upstream and downstream the impounded sections the floodplains are used for water infiltration to groundwater, which is then abstracted for fresh water supply (sand
case study Ruhr 31 filter basins). The land use distribution in the flood plains of the lower Ruhr River is shown in Fig. 5.2.-5.
5.3 Changes in the Hydromorphological Characteristics of the Water Bodies and Assessment of Resulting Impacts
Fig. 5.3.-1 and 5.3.-2 illustrate the discharge situation at gauging stations of the middle and lower Ruhr River, comparing the natural flow regime (blue line) with the manipulated flow regime (green line) integrating water abstraction for water supply and added discharge from the reservoirs.
Discharge of the middle Ruhr River 2000 Discharge of the middle Ruhr River June 2000 300 20 discharge measured 250 natural discharge discharge measured discharge without additional water supply natural discharge 15 200
150 10
100 Discharge [m³/s] Discharge [m³/s] Discharge 5 50
0 0 01.11. 01.12. 01.01. 01.02. 01.03. 01.04. 01.05. 01.06. 01.07. 01.08. 01.09. 01.10. 01.06. 03.06. 05.06. 07.06. 09.06. 11.06. 13.06. 15.06. 17.06. 19.06. 21.06. 23.06. 25.06. 27.06. 29.06.
Fig. 5.3.-1 Discharge of the River Ruhr at the gauging station Villigst (middle Ruhr section)
Discharge of the lower Ruhr River 2000 Discharge of the lower Ruhr River June 2000 50 600 discharge measured discharge measured natural discharge natural discharge 500 40 discharge without additional water supply
400 30
300
20 200 Discharge [m³/s] Discharge Discharge [m³/s] Discharge
100 10
0 0 11.99 12.99 01.00 02.00 03.00 04.00 05.00 06.00 07.00 08.00 09.00 10.00 01.06. 03.06. 05.06. 07.06. 09.06. 11.06. 13.06. 15.06. 17.06. 19.06. 21.06. 23.06. 25.06. 27.06. 29.06.
Fig. 5.3.-2 Discharge of the Ruhr River at the gauging station Mülheim (lower Ruhr section)
In these figures it is obvious, that the manipulated flow regime is very similar to natural conditions. Regarding a low flow situation (e.g. June 2000) the impact of water release from the reservoirs can be shown more clearly: Without a further water addition from the reservoirs the water abstraction for water supply would cause a critical discharge situation in the River Ruhr with the danger of drying up (e.g. Fig. 5.3.-2, graphic on the right, red line).
5.4 Discussion and Conclusions The water abstraction for water supply purposes causes a severe and significant impact on the natural flow regime of the River Ruhr. In average more than twice of the low flow discharge is abstracted for human use. The German Working Group of the Federal States on water problems (LAWA) considers a water abstraction of more than 10 percent of the low case study Ruhr 32 flow discharge as a significant impact (LAWA 2001). Without regulation a local drying up would happen in several water bodies of the River Ruhr. By adding water from the reservoirs a nearly natural flow regime was installed. But the impact of this flow regulation on the hydrological regime as well as on the ecological status of the tributaries, where the reservoirs are located, will not be discussed here, but cannot be neglected within an overall assessment and in the design of a management plan for the total catchment.
Although the impact of water abstraction is compensated by the reservoirs, so that the discharge volume should not cause a significant damage on the biological parameters, the morphological status shows deficits in every river section, with no clear distinctions between the three management units. The major ecological impact within the case study area is caused by five impounded lakes and the number of weirs along the river, which interrupt the river continuum with severe impacts on temperature and nutrient regime.
case study Ruhr 33 6 Ecological Status (7 pages)
Although in chap. 2 to 5 the whole system of the River Ruhr is described, the case study focuses on a core region in the lower Ruhr River shown in Map 4.3-1, mainly influenced by three impounded lakes. So most of the following results will be restricted to this area of 41.8 km stream length. Only when the influencing effects from upstream or downstream are important, these units are discussed as well.
6.1 Biological Quality Elements
For the identification of the ecological status, the biological quality elements "benthic invertebrate fauna" and "fish fauna" were used. Phytoplankton, macrophytes and phytobenthos were neglected, because they are of minor importance in rivers in the mountainous area. Although in the impounded lakes in the lower Ruhr River algal blooms occur regularly, phytoplankton was not considered, because under reference conditions these blooms would not happen. This means that phytoplankton may be important to define the ecological potential but not for the assessment of the ecological status. • Benthic invertebrate fauna In Northrhine-Westfalia running waters are divided into 23 different stream types. For each stream type detailed information on morphology, water chemistry, macroinvertebrates, fish, and vegetation in and along the stream under pristine conditions are available. To assess the similarity of the recent status with the reference conditions different metrics were used, e.g.: • Species composition (e.g. number of taxa, number of key-species of the stream type, German fauna index (AQEM)) • Functional group composition (e.g. feeding group composition, habitat group composition) • Saprobic index or other metrics to assess the impact of organic pollution • Diversity (e.g. Shannon Weaver index) These data are also the metrics for the assessment of stream quality based on the method of the EU-Project: "The development and testing of an integrated assessment system for the ecological quality of streams and rivers throughout Europe using benthic macroinvertebrates (Acronym: AQEM)". To compare the results with the investigations in the other German case studies, the Potamon Typie Index (SCHÖLL & HAYBACH 2001) was used in the middle and lower Ruhr River as well. In the upper Ruhr River this method cannot be applied, because of the rithralic character of this stream section. • Fish fauna To assess the fish fauna of the lower Ruhr (central case study section), data on the species composition, density and body length were considered. We added some rare species, missing in this report, from the recent fish distribution list of Northrhine-Westphalia and recent investigation results on fish migration. Combining the information on pristine fish communities with a list of historical fish distributions in Northrhine-Westfalia (FRENZ 2000) and the description of the natural fish fauna of the stream types, the reference conditions of case study Ruhr 34 the River Ruhr were characterized. To compare the actual fish situation with the reference conditions a preliminary assessment system described by GAUMERT (1999, not published) was used (important: remarks in 10.1!). To assess the fish fauna of the upper and middle Ruhr the actual fish distribution list of Northrhine- Westphalia was compared to the list of historical fish distributions in Northrhine-Westfalia and the description of the natural fish fauna of the stream type. The metrics "species similarity" (Jaccard index) (MÜHLENBERG 1993) and "Artenfehlbetrag" (lack of species) (KOTHE 1962) were used.
6.2 Physico-Chemical Elements
The total impact of human activities on the water quality of the River Ruhr (physico-chemical elements) was already described in chap. 4.2. The following impacts are known: • organic pollution by wastewater treatment plants, combined sewer overflows, and non- point sources • nutrient addition by point and non-point sources
- 2- • increase of Cl and SO4 -concentration due to the discharge from coal mines • heavy metal pollution (mainly in the sediments) due to metal processing industry in the valleys of some tributaries and increased geogenic background concentrations in some tributaries due to natural metal distribution (e.g., Sauerland, Velbert) • modified temperature regime due to – waste heat from industry and power stations, – the discharge from the reservoirs – prolonged flow time due to impoundments – geothermal heated discharge from abandoned coal mines The most important impacts influencing the ecological status in the lower Ruhr River are fluctuations in the oxygen concentrations. These fluctuations are diurnally as well as seasonally caused by the photosynthetic activity of the phytoplankton in the impounded lakes and the decomposition of algal blooms in autumn. The oxygen regime of the lower Ruhr River is shown in Fig. 6.2.-1, illustrating the mean oxygen concentrations ("Sauerstoffgehalt") per month in the year 1999 to 2000 from Ruhr km 40 to the mouth. (km
0). Severe oxygen depletions (O2 ≈ 3 mg/l) appear in summer months and in October indicating the decay of the planctonic algae. Using more detailed data, oxygen concentrations lower 1 mg/l appear for a short time.
case study Ruhr 35 Fig. 6.2.-1 Mean oxygen concentrations per month in the year 1999 to 2000 from Ruhr km 40 to mouth. (km 0). (from: RUHRVERBAND 2001a) These low oxygen concentrations in the last impounded lake "Kettwiger See" and farther downstream are lethal for most of the common fish species.
6.3 Definition of Current Ecological Status The ecological status of the three sections of the River Ruhr was assessed using fish composition and macroinvertebrate community.
• Fish fauna To assess the fish fauna of the upper, middle and lower Ruhr River the recent fish distribution list of Northrhine- Westphalia was compared to the list of historical fish distributions in Northrhine-Westfalia and the description of the natural fish fauna of the stream type. The metrics species similarity (Jaccard index) and "Artenfehlbetrag" (lack of species) (KOTHE 1962) were used (Tab. 6.3.-1, Fig 6.3.-1).
Tab.6.1.-1: Historic and recent fish community in the River Ruhr Historical Situation Recent Situation (1500 - 1950) Upper Middle Ruhr Lower Ruhr Upper Ruhr Middle Ruhr Lower Ruhr case study Ruhr 36 Ruhr River River River River River River Petromyzontidae Petromycon marinus Lampetra fluviatilis (L.) Lampetra planeri
Anguillidae Anguilla anguilla (L.)
Clupeidae Alosa alosa (L.)
Cyprinidae Abramis bjoerkna (L.) Abramis brama (L.) Alburnoides bipunctatus (BLOCH) Alburnus alburnus (L.) Aspius aspius (L.) Barbus barbus (L.) Carassius carassius (L.) Chondrostoma nasus (L.) Cyprinus carpio L. Gobio gobio (L.) Leucaspius delineatus (HECKEL) Leuciscus cephalus (L.) Leuciscus idus (L.) Leuciscus leuciscus (L.) Phoxinus phoxinus (L.) Rutilus rutilus (L.) Scardinius erythrophthalmus (L.) Tinca tinca (L.)
Cobitidae Barbatula barbatula (L.) Cobitis taenia L.
Siluridae Siluris glanis L.
Thymllidae Thymallus thymallus (L.)
Salmonidae Salmo trutta L. Salmo salar L. Oncorhynchus mykiss WALBAUM
Esocidae Esox lucius L.
case study Ruhr 37 Gadidae Lota lota (L.)
Gasterosteidae Gasterosteus aculeatus L.
Cottidae Cottus gobio L.
Percidae Gymnocephalus cernuus (L.) Perca fluviatilis L. Sander lucioperca (L.)
Fish Community River Ruhr Upper Ruhr River Middle Ruhr River Lower Ruhr River 80,00
35 % historic [1500-1950] 60,00 30 present situation 40,00 25 e 20,00 Species Lack [ 20 0,00
15 %
Species Numb -20,00 10 -40,00 5 -60,00 0 [ Jaccard-Index Upper Ruhr River Middle Ruhr River Lower Ruhr River -80,00
Fig. 6.3.-1 Assessment of the Fish Communities in the River Ruhr. –a: Comparison of historic and recent situation and b: Calculation of species similarity (Jaccard index) and lack of species comparing historic and recent communities.
Using the more detailed fish data available in the lower Ruhr River, the ecological status of the fish fauna was assessed by the (not yet published) system of GAUMERT. In this method different metrics on fish fauna quality are used. The recent fish fauna is compared to the hypothetic fish composition in the corresponding fish region and stream order and the historical data published (important: remarks in 10.1). The upper Ruhr River can be characterized as grayling region. The middle and lower part of the Ruhr River would be part of the barbel region under natural condition. Due to the impounded lakes of the lower Ruhr river there is a shift in the fish region in this stream section, with species composition now characteristic for the region of common bream. To asses the ecological status of the fish fauna of the lower Ruhr River the hypothetic fish region under natural conditions without impoundments (= barbel region) was used as reference condition. Results: • 76 % of the historical and hypothetic fish fauna are abundant ⇒ classification: good • key-species of the fish region are abundant as well as accompanying species ⇒ classification: very good case study Ruhr 38 • anadromic and katadromic fish: rare => classification: poor • key-species barbel (Barbus barbus): percentage < => classification: poor • Accompanying species: percentage 1 - > 10 % (= eudominant, dominant or recedent, some subrededent) => classification: good • Share of key-species and accompanying species = 32,6 % => classification: moderate
Conclusion: The comparison of historic fish fauna with the recent situation shows the problem of inhomogeneity of data bases. The recent fish fauna of the upper Ruhr River seems to be more diminished compared to the historical situation. In reality, in order to define the recent fish fauna only the list of fishes in Northrhine-Westphalia, with low research density in the upper stream areas, was used. So probably the species diversity is underestimated. In the lower Ruhr River the recent number of species is higher than in former times. This is caused by the immigration of neozoa and by research activities in a monitoring program, controlling fish migration at a weir. Using the metric "species similarity" these effect is obvious. Using these metrics only the presence or the absence of a species is assessed, densities are not considered. Applying these methods to the middle Ruhr River the ecological status of the fish fauna is rather close to historical, pristine conditions, indicating a good ecological status. In the lower Ruhr River a species similarity < 50% indicates the reduction of the ecological status. These methods are not feasible for the Upper Ruhr, because of lacks in data quality. Using the scheme of GAUMERT the assessment is more diversified, using presence and abundance of fish species. But means to summarize the six metrics to a single status class of ecological quality are not described. In the lower Ruhr River species characteristic for this very stream type are present, so a good ecological status theoretically can be achieved. Deficits are caused by: $ disruption of the stream continuum (reduced / missing migration of anadromic and katadromic fish due to weirs) $ siltation of the substrates and missing of gravel banks due to impoundments, so barbel can't find suitable spawning grounds (reduced / missing reproduction) $ critical oxygen depletions (chap. 6.2) and increased concentrations of free ammonia mainly in spring (toxic to sublethal conditions at times)
• Macroinvertebrates To assess the ecological status of the River Ruhr three different methods were applied. A: The macroinvertebrate community in a pristine river of the stream type "mid-sized gravel bottom mountain river (basement rocks)", not influenced by human activities is compared to the recent status. These reference conditions are described in LUA 2001c. For the stream type: "Mid-sized gravel bottom mountain river (basement rocks)" under reference conditions • 11 key species (K), case study Ruhr 39 • 43 accompanying species (A) • 27 basic species of rivers in the highlands (B) of macroinvertebrates are described. Table 6.3.-2 shows the list of these species found in the sections of the middle and lower Ruhr River. This method was not used for the upper Ruhr River because this section is a stream which can't be compared with a river section (= different types of running water with different reference conditions). Tab. 6.3.-2: List of key species, accompanying species, and basic species found in the sections of the middle and lower Ruhr River Middle Ruhr River Lower Ruhr River (Gravel Bank Neheim) (Gravel Bank Mülheim) Key Species: Baetis lutheri X Accompanying Species: Caenis rivulorum X Ephemera danica X Allogamus auricollis X Sericostoma flavicorne X Hydropsyche contubernalis X Atherix ibis X Basic Species: Dugesia gonocephala X Ancylus fluviatilis XX Gammarus pulex XX Baetis fuscatus X Leuctra geniculata X Polycentropus flavomaculatus X Rhyacophila nubila X Psychomyia pusilla X Lepidostoma hirtum X ∑ K: 1; A: 5; B: 8 K: 0; A: 1; B: 3
Results: In the middle Ruhr River only a few species, characteristic for this stream type were found, even though a natural morphological structure (gravel bank) was chosen for investigations. Although this structure is not representative for the Middle Ruhr River, all other sections with more damaged stream bed structures should have a worse, less natural macroinvertebrate community, dominated by ubiquitous species. In the lower Ruhr River also a gravel bank was investigated, but the results for the macroinvertebrate community are worse than upstream. B: The AQEM method was applied, using a multimetric method to assess the ecological status of a macroinvertebrate community, summarizing the impacts on stream morphology, saprobic status and other stressor-based metrics. The results for the Upper, Middle and Lower Ruhr River are listed in table 6.3.-3 to 6.3.-11. In the AQEM method the different stream types with different reference conditions are taken into account. Upper Ruhr River:
case study Ruhr 40 Method AQEM (not published, information under www.aqem.de available) Tab. 6.3.-3 Metrics: FauInd BMWP ShanWien HR* HK* akal* phyt* Ruhr 1 0.77 171 3.33 19.0 13.8 13.4 Ruhr 2 0.08 128 2.04 7.7 2.5 9.1
Tab. 6.3.-4 Pre-Classification FauInd BMWP ShanWien HR * HK * HR+HK akal* phyt* Ruhr 1 3 4 5 3 3 4 4 Ruhr 2 2 2 1 4 4 1 5
Tab. 6.3-5 Classification Ecological status Ruhr 1 3.5 moderate Ruhr 2 2.2 poor
Middle Ruhr River:
Method AQEM (not published, information under www.aqem.de available) Tab. 6.3.-6 Metrics: FauIndex EPTCOB-Taxa ShanWien Xyl+shred+af+pf Ak+Li+Psa* Summer -0.38 21 2.09 5.41 43.12 Winter 0.00 27 2.82 10.5 33.41 Tab. 6.3.-7 Pre-Classification FauIndex EPTCOB-Taxa ShanWien Xyl+shred+af+pf Ak+Li+Psa* Summer 2 2 2 1 2 Winter 3 2 3 2 1 Tab. 6.3.-8 Classification Ecological status Summer 1.875 poor Winter 2.5 moderate
Lower Ruhr River:
Method AQEM (not published, information under www.aqem.de available) Tab. 6.3.-9 Metrics: FauIndex EPTCOB-Taxa ShanWien Xyl+shred+af+pf Ak+Li+Psa* Summer -1.17 22.808 2.45 8.103 38.8033 case study Ruhr 41 Winter -1.19 27.835 2.53 10.531 45.7452 Tab. 6.3.-10 Pre-Classification FauIndex EPTCOB-Taxa ShanWien Xyl+shred+af+pf Ak+Li+Psa* Summer 1 2 2 2 1 Winter 1 2 2 2 2 Tab. 6.3.-11 Classification Ecological status Summer 2.0 poor Winter 2.2 poor
Results:
The investigation of the macroinvertebrate community shows for the Upper, Middle and Lower Ruhr River a moderate to bad ecological status. The data base is the same as used in method A with two gravel banks as investigation sites.
C: The Potamon Typie Index uses a list of species, characteristic for river communities. This list is not specified for different stream types. While in the AQEM method species presence as well as the abundance is used, in the Potamon Typie Index only the presence of species is considered. For the assessment all life stages or only the aquatic stages can be used. The different results, depending on the scale of life stages considered, are shown in Fig. 6.3.-2.
Potamon Typie Index (Schöll & Haybach 2001)
12
10 good 8 moderate
PTI 6
4 poor
bad 2
0 Middle Ruhr River Lower Ruhr River
Fig. 6.3.-2 Potamon Typie Index in the middle and lower Ruhr River. The bars on the left side indicate the ecological status using only aquatic life stages, for case study Ruhr 42 the right bars all life stages of macroinvertebrates were considered.
Results:
The Potamon Typie Index of the macroinvertebrate community shows for the middle and lower Ruhr River a poor to bad ecological status using only the aquatic stages of macroinvertebrates. When adults were considered as well (which would never be done in regular stream quality survey because of the biological investigation labour) the ecological status is classified as "good" to "moderate". The data base is the same as used in method A with two gravel banks as investigation sites. Also the Potamon Typie Index can't be applied to the upper Ruhr River, because this section has a rhithron community not a potamon community. Conclusions: The results of the assessment based on the biological parameter macroinvertebrates show the problem of faunistic data and the method of investigation and the choice of sampling stations: $ Problem 1: the AQEM method needs quantitative data, ascertained by a special collecting method. Already existing data can't be used. $ Problem 2: many macroinvertebrate data available are no "full-size" species lists, but only species used for calculating the saprobic index are mentioned. With these lists also method A and C can't be applied. $ Problem 3: in the upper Ruhr River a section was sampled, characterized for low organic pollution but sever morphological damage. So a sample site in the centre of a village with a significant impact of urbanisation was chosen. This site is not representative for the administrative unit "upper Ruhr River". Probably the ecological status is much higher outside the village. In the lower Ruhr River deficits are mainly caused by: $ reduced stream flow velocity with spatial stagnant sections $ siltation of the substrates and missing of gravel banks due to impoundments and bank fixation $ missing of woody debris due to channel maintenance and removal of material $ critical oxygen depletions (chap. 6.2) and increased concentrations of free ammonia mainly in spring (toxic to sublethal conditions at times) $ increased water temperature in summer due to impoundments $ modification of the natural food quality, now dominated by planctonic algae used by filter feeders
6.4 Discussion and Conclusions The physico-chemical modifications are well reflected by the biological parameters. In this case study it is obvious, that the morphological and physico-chemical modifications can be described and assessed easily, and data of sufficient quality is available. The situation concerning biological studies is different: using different methods the results cannot be compared. This can be proved for fish surveys as well as for macroinvertebrate studies. So in future more biological data, in good quality, will be necessary to assess the biological case study Ruhr 43 status, the ecological potential, and to control the efficiency of measures.
case study Ruhr 44 7 Identification and Designation of Water Bodies as Heavily Modified (6 pages)
7.1 Provisional identification of HMWB
Based on the description of physical alterations (chapter 5) and in consequence of the current ecological status as described in chapter 6, the upper and middle Ruhr River sections are provisionally identified as natural water bodies, because they are in a good ecological status (estimated, but not verified by data) or could gain this classification by minor measures. A more detailed description of the identification and designation process will be shown for water bodies 1 and 2 (Fig. 4.3-1). The typological conditions are homogeneous in the case study area with differences only in type and intensity of physical alterations. Nearly the entire core region of the River Ruhr (water body 1 and water body 2) is subject to substantial morphological alterations. Depending on different morphological alterations (of the mesoscale parameters) the following water bodies can be identified: Water body 1: Free flowing water body between the weirs at Bochum Dahlhausen and Kemnade. Water body 2: Stagnant water body from upstream of weir Kemnade to the mouth of the river Lenne upstream of Lake Hengstey.
These two water bodies can be subdivided into three sub-body types with different morphological alterations: 1. impounded lakes 2. free flowing stream sections downstream of weirs, without branches, with bank fixation 3. free flowing stream sections upstream of weirs (back water), without branches, with bank fixation
case study Ruhr 45 Tab: Sub-bodies and characteristics of the weirs
Sub-body Name Length Velocity weir; weir level Hydropower plant Sluice fish migration tool capacity (GigaWh/a) (m) Wehr Dahlhausen weir (river); 96 cm - operating no 1a Rückstau Dahlhausen 1485 stagnant 1b Winzer-Bogen 5626 free flowing Wehr Hattingen weir (river); 154 cm in Beantragung inoperable under construction 1c Rückstaubereich Hattingen 1837 stagnant 1d Fließstrecke Hattingen 3255 free flowing Wehr Blankenstein weir (river); 360 cm 24,2 inoperable 1e Rückstaubereich Blankenstein 2032 stagnant Wehr Kemnade weir (lake); 430 cm - no fish ladder (inadequately working) 2a Kemnader Stausee 4452 stagnant Wehr Herbede weir (river); 325 cm 4,4 operating fish ladder (inadequately working) 2b Rückstaubereich Herbede 2579 stagnant 2c Fließstrecke Herbede 2287 free flowing Wehr Hohenstein weir (river); 420 cm 7,27 no fish ladder (inadequately working) 2d Rückstaubereich Hohenstein 1800 stagnant 2e Fließstrecke Hohenstein 5602 free flowing Wehr Harkort (3 Bauwerke) weir (lake); 350 cm 19,5 no no 2f Harkortsee 5598 stagnant Wehr Stiftsmühle weir (river); 220 cm 6 no fish ladder (inadequately working) 2g Rückstaubereich Stiftsmühle 1266 stagnant Wehr Hengstey weir (lake); 450 cm 11,1 no no 2h Hengsteysee 4023 stagnant
case study Ruhr 46 Tab: Area restricted / potential area available
Sub-body Navigation area restricted potential area available surrounding left side surrounding right side surrounding left side surrounding right side
1a River maintenance significant 1b no (reduced river maintenance) local/ small negligible 1c no (reduced river maintenance) 1d no (reduced river maintenance)
1e no (reduced river maintenance)
2a recreation (passenger/leisure)
2b recreation (passenger 2c recreation (passenger
2d no (reduced river maintenance) 2e no (reduced river maintenance)
2f recreation (passenger/leisure)
2g no (reduced river maintenance)
2h recreation (passenger/leisure)
case study Ruhr 47 Tab: Characteristics of surrounding floodplains
sub-body Characteristics possible adverse effects on uses left side right side - 1a agriculture dominant waterworks maintenance navigation 1b small industry, agriculture locally waterworks; nature reserve projected - - 1c Industry dominant mainly agriculture - 1d small corridor of agriculture along the river mainly waterworks -
waterworks; nature reserve agriculture; waterworks hydropower generation in the valley 1e - - 2a park impounded lake; surrounding like garden / park recreational navigation (passengers/leisure) hydropower generation 2b waterworks; roads; undercut slope waterworks; agriculture passenger navigation 2c waterworks waterworks; small corridor of agriculture along the passenger navigation river hydropower generation 2d waterworks; nature reserve roads; railway - 2e small corridor of agriculture along the river roads, railway - waterworks hydropower generation 2f heterogeneous structure (agriculture; waterworks, street; housing recreational navigation park) (passengers/leisure) hydropower generation 2g highway; waterworks Urban area - hydropower generation 2h locally small corridors of agriculture along the river Roads, Undercut slope recreational navigation (passengers/leisure)
case study Ruhr 48 In summary the two water bodies can be characterised as follows:
Water body 1 (Free flowing water body between Dahlhausen and Kemnade) This water body, about 14.2 km long, is a stream section with relatively small pressures, disrupted by weirs. There is one working hydroelectric power plant in this part of the river, another one is applied for. There is neither passenger navigation nor maintenance navigation on account of two non-working sluices (Hattingen und Blankenstein). Free flowing sections are dominant with approximately 63 %. Agricultural areas are available in the flood plain, which can be utilized in order to develop the stream morphology.
Water body 2: (Stagnant water body between Lake Kemnade and mouth of Lenne River) Water body 2, about 27.6 km long, is dominated by three impounded lakes (Lake Kemnade, Lake Harkort, Lake Hengstey) and back waters of some smaller weirs. With the exception of Lake Kemnade, hydropower is generated at all of the weirs. There is passenger navigation on all three impounded lakes and on parts of the River Ruhr. Potential areas for the development of the stream are available alongside several stream sections.
The lower Ruhr River with the two water bodies described in detail will be provisionally identified as a heavily modified waterbody (see chapter 7.2.1). The section of the lower Ruhr River downstream of water body 1 passing the harbour area with bank fixation by metal peeling walls, chemical pollution and navigation should be designated as hmw. This is a "clear cut situation" as described in hmw paper 8 ver 6 - 2.4. Achieving a good ecological status affords the abandonment of the harbour or the restriction of harbour activities to the harbour basins and to move the river channel southward. With this harbour being the world’s biggest inland harbour with a trading volume of more than 2 million tons per year, a detailed quantitative analysis of the consequences of the former measures does not seem to be necessary. Neither does a transfer of the lower Ruhr River to the south seem feasible, because of intense land use conflicts with two major highways and the city district “Neuenkamp”, a part of the city of Duisburg. The remaining 88.5 km of the lower Ruhr River are provisionally identified as hmw.
7.2 Necessary hydromorphological changes to achieve Good Ecological Status (GES) 7.2.1 Required hydromorphological changes to achieve Good Ecological Status In order to develop a concept of measures to achieve Good Ecological Status it is essential to determine the relevant impacts.
% Identification and description of the main pressures causing the current state of the water body
Waterbody 1 is predominantly influenced by weirs built for water level regulation (navigation) and hydropower generation. Waterbody 2 is also influenced by weirs built for hydropower generation and water level case study Ruhr 49 regulation but the most important impact is formed by the large impoundments, Lake Kemnade, Lake Harkort and Lake Hengstey (see Map 4.3.-1). While the original purpose of these artificial lakes had been to accelerate self-purification, they now serve as recreational areas for the cities of the Ruhr Area. A list of impacts on the lower Ruhr River (waterbody 1 and waterbody 2) is given in table 5.2.1. They cause a complex system of originators and effects on stream morphology (M), water chemistry (C) and biological quality (B).
- significant reduction of flow velocity. The resulting effects are: • Reduced reaeration rates = oxygen depletions cannot be compensated by oxygen uptake in turbulent flow (C) • Sedimentation and siltation of the stream bed => accumulation of heavy metal polluted sediments (C) => anoxic sediments (C) => coating of gravel by fine sediments = loss of spawning substrate (B: fish, invertebrate fauna ) => coating of gravel by fine sediments = loss of habitat (B: fish, invertebrate fauna, phytobenthos) => organic sediments as non typical food resource (B: invertebrate fauna, fish) => covering sessile organisms with fine sediments (B: invertebrate fauna, phytobenthos, macrophytes) • loss of dynamic sediment transport, colmatation of sediment surface (M) • changes in flow velocity preference / tolerance (B: fish, invertebrate fauna, phytobenthos, macrophytes)
- significant change of river profile to lake shape Water depths rise up to 8 m with an average depth of > 2 m, while the average depth under natural condition should be lower than 0.5 m (LUA 2001) (M) The resulting effects are: • loss of shallow riffle sections => loss of spawning ground (B: fish, invertebrate fauna ) => loss of habitat (B: fish, invertebrate fauna, phytobenthos) • rising water temperatures due to increased surface area => reduced solubility of gases (C) => accelerated chemical processes / turn over rates (C) => temperature preference / tolerance (B: fish, invertebrate fauna, phytobenthos, macrophytes) • effects of turbidity: the stream bed gets aphotic => no benthic primary production (B: phytobenthos, macrophytes) • new shore line habitats for macrophytes preferring stagnant water
- significant prolongation of flow residence time In total to 7.25 days, compared to ca. 2 h flow time under natural condition. case study Ruhr 50 The resulting effects are: • development of planctonic communities (B) => phytoplankton causing fluctuation in oxygen concentration (C) => phytoplankton causing fluctuation in pH-value (C) => increased pH-values causing critical concentration in free ammonia (C) => phytoplankton blooms due to eutrophication (C, B) => secondary organic pollution in autumn due to dying plankton (C, B) • rising water temperatures due to prolonged residence time (C) => reduced solubility of gases (C) => accelerated chemical processes / turn over rates (C) => temperature preference / tolerance (B: fish, invertebrate fauna, phytobenthos, macrophytes)
- frequent interruption of river continuum by weirs and by the impounded lakes (M). The resulting effects are: • long distance migrating fish can't reach their spawning grounds (B) • populations in fish and invertebrates are isolated genetically (B)
In waterbody 1, influenced mainly by weirs built for water level regulation and hydropower generation all of the effects listed above, occur as well, except for those effects caused by impounded lake conditions: - significant reduction of flow velocity. The resulting effects are: • Reduced reaeration rates = oxygen depletions cannot be compensated by oxygen uptake in turbulent flow (C) • Sedimentation and siltation of the stream bed => accumulation of heavy metal polluted sediments (C) => anoxic sediments (C) => coating of gravel by fine sediments = loss of spawning substrate (B: fish, invertebrate fauna ) => coating of gravel by fine sediments = loss of habitat (B: fish, invertebrate fauna, phytobenthos) => organic sediments as non typical food resource (B: invertebrate fauna, fish) => covering sessile organisms with fine sediments (B: invertebrate fauna, phytobenthos, macrophytes) • loss of dynamic sediment transport, colmatation of sediment surface (M) • changes in flow velocity preference / tolerance (B: fish, invertebrate fauna, phytobenthos, macrophytes)
- deepening of river profiles. The resulting effects are: • loss of shallow riffle sections => loss of spawning ground (B: fish, invertebrate fauna ) => loss of habitat (B: fish, invertebrate fauna, phytobenthos) case study Ruhr 51 • rising water temperatures due to increased surface area => reduced solubility of gases (C) => accelerated chemical processes / turn over rates (C) => temperature preference / tolerance (B: fish, invertebrate fauna, phytobenthos, macrophytes)
- interruption of river continuum (M). The resulting effects are: • long distance migrating fish can't reach their spawning grounds (B) • populations in fish and invertebrates are isolated genetically (B)
% Development of sub-ordinate targets to achieve GES
The first step to develop measures to achieve GES is to define sub-ordinate targets. It is assumed that sub-ordinate targets can be reached by different measures or their combinations. So different scenarios to reach GES can be developed and the range of decisions can be extended. Sub-ordinate targets can be assigned to the river section as a whole or to single water bodies. To achieve Good Ecological Status in waterbody 1 and 2 measures should focus on the direct and indirect effects of human impacts. The main target has to be the elimination or at least the reduction of effects caused by impoundments (effects listed above). This can be realised by achieving "sub-ordinate targets" like: • reduction of eutrophication and algal blooms Measures: • reduction of the residence time • reduction of nutrient concentration, esp. phosphorus • increase of shaded water surface (forest, trees at the banks) • high flow conditions disturbing the streambed surface in order to avoid macrophyte and filamentous algae growth • reestablishment of river continuum Measures: • destruction of weirs • fish ladder, fish pass • bypass stream • restoration of natural stream bed structures Measures: • destruction of bank fixation to accelerate dynamic morphological processes like erosion and sedimentation • withdrawal of organic sludge, locally contaminated with heavy metals • reestablishment of oxbow lake – oxbow – river complex • reduction of stream bed maintenance activities • increase of the amount of dead wood, logs and woody debris
% Identification of relevant responsible uses
case study Ruhr 52 As mentioned above, the impounded lakes were built to accelerate self-purification. Now the purification is done by waste water treatment plants and the former beneficial objective of the impounded lakes are now of minor importance. Currently hydroelectric power plants and passenger navigation profit from the morphological alterations and constructions brought about in former times. As shown in the table above these constructions are mainly used in the water body 2 between Kemnade and the mouth of Lenne River. In the water body 1 (between Bochum Dahlhausen and Kemnade) most of the buildings are currently inoperative and the morphological alterations do not have to be maintained. The River Ruhr is no longer needed as a waterway for industrial transport of commodities and products. Navigation still serves recreational purposes for the densely populated “Ruhr area”.
7.2.2 Required measures to reach the good ecological status % Determination of Scenarios and Restrictions
To decide, if GES can be reached, different scenarios are constructed to test and assess different ways to achieve GES. These scenarios only consider realistic factors. They do not challenge the existing drinking water abstraction plants and settlement areas. Regarding the remaining potential areas in the flood plain it can be expected that the GES is achievable while maintaining these uses. The long-term protection of these uses is indispensable. 1. The drinking water abstraction plants along the Ruhr will not be modified, the bank fixation of the River Ruhr in the range of these plants has to remain to guarantee their function. (The necessity to supply people in the Ruhr area with drinking water is a "clear cut situation" and will not be discussed further.) 2. The water management using reservoirs for additional water supply to the River Ruhr in low flow periods must abide to guarantee water supply for the whole Ruhr area. 3. Settlements and industrial areas as well as flood protection devices like dykes have to remain because the location of the industrial centre "Ruhr Area" is also a "clear cut situation".
All (combinations of) measures described below were developed for the objective GES. The scenarios differ in type and intensity of their effects on uses. Scenario A refers to both water bodies and is closely orientated towards the natural status regarding the restrictions mentioned above. In scenario B there are different aims and measures for the two water bodies: 1. Water body 1 (between Dahlhausen and Kemnade): Improvement of the river continuum 2. Water body 2 (between Kemnade and mouth of Lenne River): Improvement of river continuum and reduction of physico-chemical impacts due to morphological alterations.
Description of Scenario A: case study Ruhr 53 Considering the restrictions mentioned above, the objective being closest to the natural status is a continuous stream without back-waters. This means that the impounded lakes have to be abandoned and the weirs have to be replaced by artificial riffle sections. Bank fixations can be removed locally. In the core region with drinking water abstraction plants and settlements continuously lined up on one side of the river, bank fixations can only be removed on the opposite side of the river. Thus, dynamic streambed migration can be achieved in some stream sections. The establishment of alluvial forests or groves is an accompanying measure. Further on the input of organic material such as leave litter and wood debris is an important factor for the development of the aquatic fauna. By reattaching oxbows spawning grounds for cyprinid fish species and habitats for young fish can be developed. Because of heavy metal pollution, sludge removal from the bottom of the lakes is a likely measure to be taken before the dams can be removed.
Description of Scenario B: As an alternative to scenario A selective factors preventing the GES can be eliminated. Hydro power generation and recreational facilities, especially passenger navigation are maintained in principle. The affected uses are reduced only gradually as far as it is necessary to reach the GES.
1. Water body 1 (between Dahlhausen and Kemnade) The existing weirs are provided with optimized fish ladders or bypass ways. The potential areas are used as described in scenario A.
2. Water body 2 (between Kemnade and Mouth of Lenne River) Stable planktonic communities cannot occur in lakes, when the residence time is less then two days (UHLMANN 1988, KLAPPER 1992). In this short time the reproduction rate is smaller than the loss rate of cells washed out. WALZ & WELKER (1998) reported from rapidly flushed lakes, that the development of zooplankton weakened in residence times smaller than 8 days. So in our study on the impounded lakes of the River Ruhr, we calculated a situation with residence times of 4 days, where minor planktonic development occurs but algal blooms with the resulting secondary effects on water chemistry can be avoided. To achieve this, the volume of the impounded lakes has to be reduced by lowering the water height. In the scope of this case study only a rough calculation can be carried out, because a model to describe the actual residence time depending on the lake morphology and flow dynamic is to be prepared, but does not exist yet. So the exchange times striven for and the resulting lake shape have to be estimated. The following assumptions are taken: • Total volume of the three lakes in the core region of the case study: 9.4 Mio. m³ • Low water flow of the River Ruhr: 15 m³/s • Mean residence time of the lakes: 9 400 000 m³ / (15 m³/s *24*60*60 s/d) = 7.25 days
This calculation fits well with the values given in KOPPE ET AL. (1983a, 1983b, 1985). In contrast to KOPPE ET AL. the determination of the maximum lake volumes is based on the low water flow when critical situation are very probable (Low water flow and high primary production causing oxygen depletion by night occur at the same time and cause physico- chemical impacts).
case study Ruhr 54 The maximum volume to achieve GES is calculated as follows: 4 d x (24 x 60 x 60)s/d x 15 m³/s = 5.2 Mio m³ Some restrictions and assumptions have to be considered in scenario B: - No modification of Lake Hengstey because the lake is used as lower lake of a reservoir power station
- Lake Kemnade provides optimum conditions for the lowering of the water height, because hydropower generation is not affected.
- The weirs of the lakes are adjustable, so there will be no costs for a conversion
- it is roughly assumed that the decrease of the water level is proportional to the decrease of the lake volume. (Detailed information on the lake morphology and the water levels is missing, so the real effects of lowering the mean water level is not predictable)
Regarding these restrictions the following measures are to be taken: - 2.10 m lowering of the water level of Lake Harkort (lake volume reduction: 1 900 000 m³)
- 3.30 m lowering of the water level of Lake Kemnade (lake volume reduction: 2 300 000 m³)
- maintenance of passenger navigation in well defined shipping lanes
- construction of bypass streams (low flow discharge 1.5 – 2 m³/s) at Lake Harkort and Lake Kemnader beginning just upstream the stagnant part of the river, passing the reduced impounded lake with a confluence downstream the dam (the area for the new bypass streams can be gained by the reduction of the lake surface due to the reduction of the volume)
- construction of a bypass stream at weir Herbede (potential areas available).
- Constructing fish ladders or bypass ways at weirs Hohenstein, Lake Hengstey and Stiftsmühle (construction of bypass stream is not possible because of restricted areas nearby)
Accompanying measures are to be taken as described in scenario A (removal of bank fixation, planting of alluvial forest, grove or wood, reattachment of oxbows, removal of sludge).
7.2.3 Impact on water uses and significant adverse effects According to art. 4(3) WFD the designation process of HMWs has to consider whether “the changes to the hydromorphological characteristics of that body, which would be necessary for achieving good ecological status, would have significant adverse effects on [...] • navigation, including port facilities, or recreation; • activities for the purposes of which water is stored, such as drinking-water supply, power generation or irrigation; • water regulation, flood protection, land drainage; or • other equally important sustainable human development activities.”
case study Ruhr 55 Regarding the different scenarios, the adverse effects on uses have to be considered in detail: a) general definition of criteria and levels of significance b) qualitative description of adverse effects on uses c) identification of significantly affected uses based on the levels of significance
Criteria and levels of significance for adverse effects on uses For the decision process a socio-economic sectoral analysis as well as an individual economic analysis is necessary. • Hydropower generation: The degree of hydro power production decreases due to the described measures is used as a level of significance. A loss of 2% of the energy produced per year is determined as an acceptable adverse effect for the economic sector and the single user (level of significance). For the sectoral analysis the values are related to the energy produced by hydro power in Northrhine-Westphalia (NRW) per year.
- Total of NRW: 516 GWh/a
- Total of River Ruhr: 235.38 GWh/a (=46 % of total NRW)
- core region of this case study: 72.48 GWh/a (= 31 % of the production at the River Ruhr, 14 % of the production in NRW) Assuming that there are intentions to reduce energy production at other hydroelectric power plants as well, 2% of the hydro power energy produced in the core region of this case study (72.48 x 0.02 = 1.45 GWh/a) is considered as sectoral level of significance. • Passenger navigation The loss of recreation quality for people and the limitation of passenger navigation in time and expanse are recognised as criteria of significance. Sectorally passenger navigation is regarded in its function for recreation, individually it is regarded as a private company working economically. As there is no legal right of navigation in the core region of this case study no individual economic analysis of passenger navigation has to be taken into account. • Maintenance navigation Criteria of significance are the limitations of maintenance navigation in time and expanse. The level of significance will be reached, when the efforts to maintain the streambed of the River Ruhr that way, that GES can be achieved, are too expensive, so the authority responsible for maintenance activities cannot raise the money necessary to do so. While working on this case study it was not possible to get the data to define the level of significance in detail. We assume that there will be significant adverse effects on maintenance navigation, because already now there are stream sections hard to be maintained by boat (locally low water levels and different stream bank structures). Realizing the measures mentioned above, the efforts for stream maintenance can get critical, with stream sections, where maintenance navigation won't be possible. • Drinking water supply The increasing operating expenses for water production by achieving the GES are case study Ruhr 56 considered as criteria of significance. The increasing expenses can be caused by augmented concentrations of suspended solids in the water column due to increased hydromorphological dynamic. Adverse effects on drinking water production only exist for waterworks producing drinking water by adding water from the river Ruhr to the groundwater by artificial infiltration. Waterworks using only groundwater are not concerned. But in total the drinking water production won't be reduced. While working on this case study we were not able to justify the criteria of significance and to get a financial level of significance from the waterworks. In the scope of this case study possible adverse effects on water supply will be neglected. Assuming the functionality of the waterworks won’t be affected, the existing periods of augmented concentrations (high flow conditions) have no adverse effect on water supply. • Agriculture The loss of area used for agriculture is used as criterion of significance. This criterion is especially important for the individual economic analysis. A sectorial economic analysis can be neglected, because the need of producing food in the Ruhr area is of minor importance. Concerning the individual economic analysis the level of significance is the loss of 2 % of area used for agriculture. For a rough calculation we assume the reduction of 2 % of agricultural area due to measures will be the same for every user (here: farmer) so this percentage is used as a level of significance in the individual economic analysis. To estimate the percentage of reduction, the loss is related to the agricultural area of the whole catchment of the River Ruhr. As it has to be expected that there is also the need for space to develop the stream in other sections, the area reduced should be related proportionally to the agricultural area in the core region of this case study: • Total length of streams in the catchment area: 4 573 km • Total area used for agriculture (LN) in the catchment area: 1 400 km² • Length of stream section in the core region: 42 km (about 1 % of total length) • area used for agriculture (LN) in the core region 14 km² (=1 % of agricultural area in the whole catchment) => Level of significance for the core region: 2 % of 14 km² = 0.28 km²
Scenario A: % Qualitative description of adverse effects and identification of significantly affected uses Scenario A has adverse effects especially on hydro power generation. The discharge and difference in water level altitude is defining the energy produced by hydropower generation. After destruction of the weirs hydropower production is to be abandoned. • Sectoral analysis: In Northrhine-Westfalia 516 GWh/a are produced by hydropower. In the core region there is a total energy production of 72.48 GWh/a = 14 % of the annual electricity produced by hydropower in Northrhine-Westfalia. The expected adverse effects are considered as significant. The designation of HMW is justified by sectoral and individual economic analysis. Passenger navigation can’t be run in the same way as before. The loss of lakes as case study Ruhr 57 “landscape experience” reduces the attractivity of passenger navigation. Due to the reduction of the water surfaces and the lowering of the water level, when abandoning the lakes, navigation is limited in time and space, especially in low flow periods. The routes and periods in which navigation with the existing ships is possible will be significantly reduced, so passenger navigation will be abandoned because of missing rentability. Regarding maintenance navigation the navigability of the river Ruhr will be more difficult because of the reduced water depth and a different stream bed structure (e.g. sandbanks). It is likely that maintenance navigation will no longer be feasible. Measures to accelerate dynamic processes in streambed morphology (e.g. by destructing bank fixations) will cause increased erosion rates and streambed migration, reducing area used for agriculture. In the core region of the case study about 13 km along the river are used for agriculture. Using a 50 m corridor in the valley of the River Ruhr as space for dynamic stream bed migration and as a buffer zone for the retention of nutrients, pesticides and eroded solids, there will be a reduction of 0.65 km² of agricultural area. As this is more than twice as much as 0.28 km² (level of significance) a significant adverse effect on farms can be expected. In summary the following significant adverse effects on uses can be expected by realising scenario A: - total loss of hydropower production
- expected abandonment of passenger navigation
- significant restriction or complete abandonment of maintenance navigation
- significant loss of agricultural area
There are some differences between the two water bodies: - Passenger navigation is abandoned only in water body 2 (between Kemnade and Mouth of Lenne River
- Concerning hydropower generation water body 2 is more strongly affected than water body 1: (energy production by hydropower plants about 48 GWh/a in water body 2 compared to about 24 Wh/a in water body 1).
- Concerning maintenance navigation and agricultural land use the effects are comparable in both water bodies Scenario B: In scenario B hydropower generation can be maintained but the energy production at weir Harkort will be reduced proportionally to the lowering of the water level. The loss will be about 12 GWh/a. This is ten times as much as the level of significance and is considered sectorally and individually significant even if because of the size of the power plant Harkort hydro power generation will very likely remain profitable. Passenger navigation can also be maintained and the existing ships will further be operational (BfU 2000). If necessary a shipping lane will have to be maintained. The lake will be sustained as “landscape experience” but it will be reduced in its length and area. Adverse effects on passenger navigation consist in the shortening of the routes, the possible additional effort to maintain a shipping lane and the conversion of the landing places due to
case study Ruhr 58 the modification of the shore line. Adverse effects on maintenance navigation are possible due to a more difficult navigability and due to the additional efforts to maintain the new bypass streams. The effects of the removal of bank fixations are comparable to the descriptions in scenario A. Additionally space is required for the construction of bypass streams. In summary the following significant adverse effects on uses can be expected by realising scenario B: - reduction of hydropower generation
- limitation of passenger navigation
- limitation of maintenance navigation
- loss of area for agricultural land use
There are some differences between the two water bodies: - Passenger navigation is limited only in water body 2 (between Kemnade and mouth of Lenne River)
- Concerning hydropower generation only water body 2 is affected.
- Concerning maintenance navigation and agricultural land use the effects are comparable in both water bodies
7.2.4 Impacts on the wider environment Scenario A: The abandonment of the impounded lakes will have a significant adverse effect on the groundwater level. The pressure of the water column in the lake on the hyphorheic interstitial will decrease, so the subterranean interflow to the banks will be reduced. This can cause groundwater depending ecosystems like oxbow lakes or bogs to run dry. If sludge removal should be necessary, the material probably will be deposed in the floodplain (as it was done already in the past), covering the actual vegetation and endangering the ground water by washing out heavy metals. The land filling also changes the natural landscape shape.
Scenario B: Construction of a bypass stream affords the digging of a new watercourse. Removed soil must be deposed, filling the natural landscape and covering the actual vegetation. The effects of sludge removal are described in Scenario A.
7.3 Assessment of Other Environmental Options According to scenarios A and B both water bodies might be identified as heavily modified because of the significant adverse effects on uses. But in scenario B the uses along water body 1 (between Dahlhausen and Kemnade) are affected to a minor degree. To reach a final decision the method to designate HMWs will be continued according to art. 4 (3) b WFD.
case study Ruhr 59 7.3.1 Identification and definition of the beneficial objectives served by the modified characteristics of the water body Beneficial objectives of the different uses: • hydro power generation:
Power generation from regenerative sources of energy, no CO2-emmissions, no radioactive waste • passenger navigation recreational offering for the densely populated Ruhr area • maintenance navigation maintenance of the streambed for passenger navigation, protection of the waterworks and agricultural land • agriculture preservation of agricultural properties, conservation of landscape character anthropogenically formed during centuries.
7.3.2 Alternatives to the existing ”water use“ The description of alternatives is done by regarding two factors: • technical feasibility, • assessment of better environmental options
• Hydropower generation Wind power and solar energy are other examples of regenerative sources of energy without
CO2–emissions. Both procedures are well engineered but wind power today has a higher degree of efficiency than solar energy production. Therefore in the following wind power is considered as alternative. The effects of wind power and hydro power on the wider environment differ from each other very much and in the case of wind power they are not thoroughly researched yet, which makes a comparison difficult. Concerning global climate protection both energy sources have to be regarded as good options. Wind power plants can have negative effects on biotope structure and on certain animal species like, e.g., birds. In theory the impact of every single wind power plant replacing a hydropower plant would have to be assessed in order to evaluate, if this special building is really a better environmental option sensu Art. 4 (3) WFD. In this case study we assume that wind power generation is a better or at least a comparable environmental option.
• Passenger navigation Recreational activities which can be established as a result of the more pristine character of the River Ruhr and the Ruhr valley is regarded as an alternative to passenger navigation. Included are better fishing facilities and more attractive natural experiences. These recreational activities are regarded as better or comparable environmental options.
• Maintenance navigation Alternatives to maintenance navigation are only necessary in scenario A. As maintenance navigation will probably be abandoned in scenario A the maintenance of the stream bed in future will be focused on the protection of the waterworks. This can be done without using ships. But it can not be decided, whether this is a better environmental option. case study Ruhr 60 • Agricultural land use In principle the reactivation of abandoned agricultural land is an alternative to the agriculture in the flood plains, which can be damaged by morphological processes of the river. But in the core region of this case study there are too few abandoned fields, which can be reactivated. But new agricultural land can be developed by using the former lake ground after destroying the weirs or reducing the lake surface area.
7.4 Designation of Heavily Modified Water Bodies According to art. 4 (3) b WFD the decision on the environmental objective (GES or GEP) has to consider whether the costs are proportionate. The costs to achieve the GES have to be compared to the general willingness of payment. But it must not be neglected that there are also costs to achieve the GEP. The final designation should be based by comparing the costs to achieve the GES with the costs to achieve the GEP. This seems to be necessary as by the change of objectives and perhaps the changing of water body type different measures and costs can occur. This can be shown by the following example: In scenario A (GES) the remaining physico-chemical pressures from diffuse sources are of minor importance. But to reach the GEP great efforts to reduce the phosphorus concentrations have to be taken (see chapter 8). The WFD neglects that there can also be human benefit by achieving the GES. As the human benefit might be calculated monetarily (use values) it should be identified before analysing any other costs. The final economic analysis and designation process should consider possible human benefit. Three steps are necessary:
- identification of human benefit by achieving GES
- calculation of costs to achieve GES and assessment whether they are proportionate
- comparison with costs to achieve GEP
7.4.1 Identification of human benefit by achieving GES
Scenario A: We expect that the natural character of the Ruhr valley will increase by realising scenario A. As a result there will be more attractive nature experiences (nature watching, fishing, hiking). The former surface of the lakes might be used for agriculture (in accordance with natural management). In a free flowing River Ruhr without impoundments, eutrophication would not be of any importance, because plankton would not develop and benthic macrophytes and algae would not appear in high densities. The dynamic transport processes of the stream bed substrate will prevent stable conditions for growing of these plants. So additional measures in waste water treatment, reducing the emission of nutrients like phosphorus to control eutrophication, can be avoided. Without advanced effluent control measures like phosphorus precipitation or biological phosphorus elimination at the waste water treatment plants, the costs of waste water treatment can be reduced. case study Ruhr 61 Abandoning the lakes, the area can be used for spate retention (retention volume nearly 9 Mio. m³). The costs of sludge removal will decline to zero.
Scenario B: In scenario B positive effects on recreational activities can be expected as well. The construction of the bypass streams and accompanying measures increase the attractivity of the landscape and the fishing facilities. Due to assessable weirs the area can be used for spate retention (retention volume nearly 4 Mio. m³). In contrast to scenario A positive effects on agriculture and wastewater treatment are regarded as negligible because the lakes will remain.
case study Ruhr 62 Effects of Scenario A
adverse effects on uses positive effects on uses Alternatives to the existing use Impacts on wider (better environmental options) environment hydro power generation passenger navigation maintenance navigation agriculture flood protection drinking supply water recreation agriculture treatmentwastewater flood protection hydro power generation passenger navigation maintenance navigation agriculture flood protection
replacement of weirs by ◗ ◗ 1 ❍❍❍++ (+) (+) ++ Biotopes related to the artificial riffle sections 2 2 ground water level are endangered of drying up partial removal of bank ◗ ❍ ❍❍ ◗4 ❍ + fixation ❍ 3 ◗5 + + xx planting of alluvial forest, ❍ ❍ ❍❍❍❍❍❍ + - grove or wood
development of oxbows ❍❍❍❍❍❍ +(+)
removal of sludge ❍❍❍❍❍❍ muddy landfills in the floodplains
case study Ruhr 63 Effects of Scenario B Water Body Dahlhausen to Kemnade
adverse effects on uses positive effects on uses Alternatives to the existing use Impacts on wider (better environmental options) environment hydro power generation passenger navigation maintenance navigation agriculture flood protection drinking supply water recreation agriculture treatmentwastewater flood protection hydro power generation passenger navigation maintenance navigation agriculture flood protection
construction of bypass ◗6 ❍ ◗7 ❍❍ ++ (+) soil built landfills in the stream Stiepel ❍ floodplains partial removal of bank ❍ +/❍ + ❍ ❍❍◗3 ◗4 ❍ + fixation xx ◗5 x ❍ -
planting of alluvial forest, ❍❍❍❍❍❍ grove or wood +
case study Ruhr 64 Effects of Scenario B Water body Kemnade to Mouth of Lenne
adverse effects on uses positive effects on uses Alternatives to the existing use Impacts on wider (better environmental options) environment hydro power generation passenger navigation maintenance navigation agriculture flood protection drinking supply water recreation agriculture treatmentwastewater flood protection hydro power generation passenger navigation maintenance navigation agriculture flood protection
❍ ❍ lowering of the water height (+) ◗8 ❍❍❍ ◗9 ◗9
construction of bypass ❍6 ❍ ◗7 ◗15 ❍❍++ (+) soil built landfills in the streams/ fish ladders floodplains s ❍ ❍ ❍ +/ + partial removal of bank ❍❍◗3 ◗4 ❍ + xx ❍ fixation ◗5 x -
planting of alluvial forest, ❍❍❍❍❍❍ + grove or wood
removal of sludge ❍❍❍❍❍❍ Muddy landfills in the floodplains
case study Ruhr 65 • Symbols: Adverse effects on uses Abandonment of use ◗ Modification of use (significant restriction) ❍ Maintenance of use (minor restriction)
Positive effects on uses ++ high +distinct (+) possible
Alternatives to the existing use + better option exists ❍ comparable option exists - worse option exists x without relevance
Adverse effects: 1. hydropower generation not feasible 2. significant restrictions in time and space, abandonment likely 3. navigability getting difficult due to natural stream bed structures (e.g. sand banks, gravel banks) 4. loss of area 5. problems with higher suspended solid concentrations may occur 6. reduced hydropower production due to decreased flow through (negligible) 7. bypass stream has to be maintained (probably without a ship) 8. reduced hydropower production due to decreased water level 9. local restrictions are possible
Positive effects: spate retention: increase of retention volume agriculture: increase of area (former surface of the lakes) waste water treatment: accelerated reaeration rates help to fulfil legal standards of water quality, water from the reservoirs won't be used any more to dilute critical chemical concentrations downstream (high ammonia concentrations in winter)
66 recreation: − more attractive natural experience − better fishing facilities
7.4.2 Economic analysis of measures to achieve GES Method The costs to achieve GES are calculated. They include:
- Costs to replace existing uses (KV)
- Costs realising alternatives to achieve the same benefit (KA).
- real costs to realise measures (KP)
The costs are assessed by comparing willingness to payment for nature protection (non use value) (ZN) including expectable human benefit (use values) (W) with the estimated costs to achieve the GES. The costs are considered proportionate if the benefit-cost-quotient is at least equal to 1:
ZN + W ≥ 1 KV + KA + KP
According to HAMPICKE (quoted in MEYERHOFF 1998, S. 68) the willingness to payment for areas of ecological value amounts to 500 € per hectare and year. The size of the flood plain area in the core region is used for this calculation. Considering a flood plain area of 29.2 km², results in a willingness to payment of 1,460,000 € per year. As the WFD has to be realised within 15 years a total amount for measures of 21,900,000 € results (interest rates neglected).
Scenario A Scenario A is rather drastic, modifying the structure of the Ruhr valley in total. So the two water bodies are not discussed separately. The abandonment of hydropower generation is the main adverse effect in scenario A. For the calculation the following assumptions are taken:
- The operating companies of the hydroelectric power plants have legal rights to produce electricity. These rights are valid for the whole period of 15 years. Therefore costs for the replacement of existing uses have to be calculated for a period of 15 years.
- The operating companies can't be forced to pay for ecological measures as it would be the case when applying for new rights or for the prolongation of existing rights. There are six hydroelectric power plants in the core region of this case study with a total installed capacity of 15 220 kW and an energy production of 72.48 GWh/a. When abandoning hydropower generation, the operating companies have to be compensated for the lost profit. The calculation of the profit is based on investment costs of 2.556,46 € for each kW installed capacity (FLOECKSMÜHLE 2001). According to EEG a salary of 0.0665 €/kWh will be paid for the energy produced. This is a rough calculation, for some of the electricity will be used by the producer himself. case study Ruhr 67 Tab: calculation of replacement costs (=lost profit) per year Total investment costs 15 220 kW x 2 556.46 € 38 909 321.20 € Total salary per year 72 480 000 kWh/a x 0.0665 € 4 819 920.00 € running costs per year 3 209 744.09 € - operating costs 2 % of the annual salary 96 398.40 € - capital charges 6 % of the investment costs 2 334 559.27 € - Maintenance costs 2 % of the investment costs 778 186.42 € Total profit per year Salary minus costs 1 610 175.91 € (without tax)
In this calculation the capital charges are rather uncertain. Most power plants are older than 50 years, so the standard values used above probably are not realistic, which would lead to significantly higher compensation costs. On the other hand only lost profits minus taxes have to be compensated. Additionally the costs to compensate the profits of the reservoir power station Koepchenwerk have to be considered. These profits can not be calculated in the scope of this case study because of missing values. Obviously the costs to compensate these profits are higher than the willingness of payment. The human benefit of realizing scenario A couldn't be calculated monetarily. But probably they are not able to compensate the costs of restricted uses, costs of alternative energy production (better environmental options), and cost to realize measures. Conclusion: The realisation of scenario A is not a feasible aim.
Scenario B In scenario B the two water bodies are discussed separately. Based on the length of the water bodies the willingness of payment during a 15-year period (21 900 000 €) is divided in a ratio of 1:2 (water body 1 (between Dahlhausen and Kemnade) : waterbody 2 (between Kemnade and mouth of Lenne River) resulting in a willingness of payment of 7,300,000 € for water body 1 and 14,600,000 € for water body 2.
• Water body 1 (between Dahlhausen and Kemnade)
In the following table willingness of payment, use values and costs for a period of 15 years are listed: willingness of payment: 7 300 000 € human benefit (use values): no Costs to replace existing uses: loss of agricultural area (255 000 m² x 5 €) 1 275 000 € case study Ruhr 68 2 % reduction of energy production (low flow discharge required for ecological reasons) at weir Stiepel (24.2 GWh/a x 2% x 0.0665 €/kWh x 15 a): 482 790 € costs realising alternatives (wind engines):
According to www.wasserkraft.org each kWh produced by wind engines has to be subsidized with 0.087 €. 24.2 GWh/a x 2% x 0.087 €/kWh x 15 a 631 620 € other investments (bypass streams, fish migration devices, removal of bank fixation, planting measures): 3 500 000 €
Calculation of benefit-cost-quotient: 7 300 000 = 1.24 1 757 790 + 631 620 + 3 500 000
Conclusion: The willingness of payment is higher than the calculated costs in water body 1, so the GES should be achieved.
• Water body 2 (between Kemnade and mouth of Lenne River) In this scenario only the hydroelectric power plant Harkort is affected, because there is no hydropower generation at the weir Kemnade. The power plant Harkort has an installed capacity of 6,100 kW and an average energy production of 19.5 GWh/a. The actual profit per year is calculated in the following table: Tab: Calculation of actual profit per year (power plant Harkort) Total investment costs 6 100 kW x 2 556.46 € 15 594 406.00 € Total salary per year 19 500 000 kWh/a x 0.0665 € 1 296 750.00 € running costs per year 1 273 487.48 € - operating costs 2 % of the annual salary 25 935.00 € - capital charges 6 % of the investment costs 935 664.36 € - Maintenance costs 2 % of the investment costs 311 888.12 € Total profit per year Salary minus costs 23 262.52 € (without tax)
The total profit per year has to be compared to the future profit after lowering the water level. The lowering of the water level from 3.5 m to 1.4 m causes a reduction of 39 % in the energy produced (loss of energy production 11.895 GWh/a). The difference between the actual and the future profit has to be compensated.
case study Ruhr 69 Tab: Calculation of the future profit (forecast) at power plant Harkort after lowering the water level Total investment costs 6 100 x 2 556.46 € 15 594 406.00 € Total salary per year 7 605 000x 0.0665 € 505 732.50 € running costs per year 1 257 667.13 € - operating costs 2 % of the annual salary 10 114.65 € - capital charges 6 % of the investment costs 935 664.36 € - Maintenance costs 2 % of the investment costs 311 888.12 € Total profit per year Salary minus costs -751 934.63 € (without tax) In both tables it can be assumed that the capital charges are considerably lower. Neglecting this, the difference between the results of both tables is about 775 000 €, which has to be compensated. If the beneficial objective “energy production by hydropower as a regenerative source of energy” is to be replaced by the environmental option “windpower”, the future operating company has to be subsidized with 0.087 €/ kWh
Calculation of costs for the production of energy by wind engines per year Salary for the electricity sold 0.077 €/ kWh Production costs 0.164 €/ kWh Balance calculation -0.087 €/ kWh Total costs to produce 11.895 GWh by wind engines 1 034 865 €
As use values especially the increased retention volumes of 4 Mio. m³ have to be mentioned. At the river Ruhr the increased retention capacity is of minor importance, because the risk of damages due to spates is rather low. But beneficial effects on the high water conditions at the lower Rhine area are to be expected. In the economic analysis this should be considered, but in this case study detailed data were not available. So the use value of increased retention is estimated with 2 Mio. €. In the following table willingness of payment, use values and costs for a period of 15 years are listed: willingness of payment: 14 600 000 € human benefit (use values): 2 000 000 € Costs to replace existing uses: loss of agricultural area case study Ruhr 70 (400 000 m² x 5 €) 2 000 000 €
reduction of energy production (power plant Harkort) 11 627 957 € 2 % reduction of energy production (bypass stream) at weir Herbede (4.4 GWh/a x 2% x 0.0665 €/kWh x 15 a): 87 780 € costs realising alternatives (wind engines):
According to www.wasserkraft.org each kWh produced by wind engines has to be subsidized with 0.087 €. 11.895 GWh/a x 0.087 €/kWh x 15 a 15 522 975 € other investments (bypass streams, fish migration devices, removal of bank fixation, planting measures, maintenance of shipping lane): 8 500 000 €
Calculation of benefit-cost-quotient: 14 600 000 + 2 000 000 = 0.44 13 715 737 +15 522 975 + 8 500 000
Conclusion: Obviously the costs to achieve GES are higher than the willingness of payment and the use values. It seems not possible to realise scenario B in water body 2. Especially the costs to replace existing uses and the costs for realising alternatives are very high. As a new solution we developed a scenario C, in which Lake Kemnade is abandoned and hydropower generation at the weir Harkort is spared as far as possible. The volume of Lake Harkort has to be reduced by about 1.9 Mio. m³. In this case there still would be costs between 25 and 27 Mio. €. It does not seem possible to realise scenario C as well, because the benefit-cost-quotient is significantly less than 1.
7.4.3 Comparing the costs to achieve GES with the costs to achieve GEP The costs to achieve GEP calculated below refer to water body 2, because in water body 1 it seems possible to reach the GES. As explained in chapter 8 the main measures to achieve the GEP have to be: - reducing the phosphorus concentration
- restoring the stream continuum
- ameliorating measures along the borders of the lakes
The phosphorus concentration can be reduced by building up buffer stripes along the River Ruhr and its tributaries. Along the streams, which are surrounded by areas used for case study Ruhr 71 agriculture (1 720 km) a buffer stripe of 5 m on each side is assumed. Concerning the River Ruhr only 30% of the costs for this measure are calculated, as the remaining costs would be necessary anyway to reach the GES in the smaller tributaries. The stream continuum is restored by building six fish migration devices (fish pathways, fish ladders) at the weirs. Replacement costs for a reduced hydropower production are considered as negligible. To ameliorate the shore line of the lakes, reeds should be introduced and bank fixations at least on one side of the river should be removed. The resulting costs are: costs to replace existing uses: loss of agricultural area along the River Ruhr (ameliorating measures) (400 000 m² x 5 €) 2 000 000 € Loss of agricultural area to reduce phosphorus concentration (buffer zones along tributaries in the catchment area) (17 200 000 m² x 3 € x 30%) 15 480 000 € other investments (6 fish migration devices, ameliorating measures along the borders): 9 500 000 €
The resulting benefit-cost-quotient is: 14 600 000 = 0.54 17 480 000 + 9 500 000
This benefit-cost-quotient is only slightly higher than the one in scenario B (0.44). That means that the costs to achieve GEP are also higher than the assumed willingness of payment.
7.4.4 Designation of water bodies and objectives Regarding the costs, neither the GES nor the GEP can be achieved in water body 2 within a period of 15 years. For this stream section at least temporarily less stringent environmental objectives have to be taken into account. Regarding a possible prolongation time of 12 years to realise the WFD, it seems possible to achieve the GEP. In contrast to the GES, the measures to achieve the GEP are mainly singular costs. Over a prolonged time it will be possible to procure the money necessary for implementing the GEP. For a final designation it has to be considered that the sub-bodies with cost-extensive measures are close to water body 1 (with the objective GES). It seems economically and ecologically realistic to extend water body 1 so that it includes the subbodies 1a to 2e. The final designation might be: Objective GES: water body 1 + subbodies 1a to 2 e (Dahlhausen to Harkort-See) case study Ruhr 72 Temporarily less stringent environmental objectives; 27 years later objective GEP: water body 2 minus subbodies 1a to 2e (Harkort-See to mouth of Lenne River)
7.4 Discussion and Conclusions While working on this case study it turned out that the given method was practicable. Only in parts it had to be elaborated. The following steps are considered especially important: The provisional identification of water bodies should regard typology as well as morphological alterations. If possible, different types of morphological alterations should be identified. It is suggested to divide the provisionally identified water bodies into subbodies with a minimum length of about 1.5 km. This step can be of great importance for the final designation of water bodies. A causal analysis of actual pressures is essential in order to derive necessary changes. This analysis has to include both ecological deficits and the causing uses. So pressures might be identified which are caused by uses no longer existing. It is assumed that the deficits can be remedied by different measures. To make the decision process transparent it is recommended to develop different scenarios for the solution. The scenarios and their measures should be orientated to achieving the GES as this is the norm given in the WFD. Under no circumstances should the scenarios be developed considering most of the uses as indispensable. Restrictions should be made only for “clear cut situations”. To forecast possible adverse effects on uses by achieving the GES it is necessary to develop criteria of significance. The following uses should be regarded: - uses listed in art. 4 (3) WFD
- uses based on legal rights
- uses designated be a valid development plan
It is especially important to define the relevant beneficial objectives of the regarded uses. They must be defined both sectorally and individually. The same use can have different beneficial objectives by sectoral or individual regard. The determination of other environmental options should be made regardless of the question whether they can be assessed as better option. This should be discussed only in the final designation process. The division of the designation process into a qualitative and a quantitative part should be maintained to guarantee a high grade of transparency and understandability. This seems to be important as future decision processes will have to cope with quite a lot of assumptions and uncertainties. This holds especially for individual economic analyses. In the economic part of the decision process the comparison of costs with expectable human benefit and willingness to payment was practicable. The “benefit-cost-quotient” of 1 or more characterises the GES as achievable. Its value also characterises the effectiveness of measures. The economic analysis should include: case study Ruhr 73 - willingness to payment (non use values)
- use values
- costs to replace existing uses
- costs for the establishment of alternatives to achieve the same benefit according to art. 4 (3) b WFD
- real costs to realise measures
The final designation process should regard the comparison of costs to achieve the GES and the GEP. The reasons are: - If the costs to achieve the GES are nearly comparable to the costs to achieve the GEP then the GES should be the objective.
- If the costs to achieve the GES as well as the GEP are disproportionate then less stringent objectives have to be considered.
case study Ruhr 74 8 Definition of Maximum Ecological Potential
Assessing a heavily modified waterbody, two different cases have to be considered:
Case A: Caused by significant human impacts the waterbody changes the surface water category (e.g.: reservoir: reference under natural conditions: river, reference as heavily modified water body: lake (= best comparable water body)). Or the surface water category will remain but the water body changes the water body type ( e.g. river downstream a reservoir: reference under natural conditions: medium sized river, reference as heavily modified water body (so the designation is reasonable): small river (due to the effect of rhithralization)) In case A the assessment procedure is the same as in natural water bodies, only the definition of reference conditions has changed.
Case B: In case B the modification in the waterbody caused by human impacts don't have a corresponding natural situation (e.g. urbanization). Assessing heavily modified water bodies belonging to case B, the general reference condition will be the ecological status of this particular waterbody under natural conditions. But to assess the water body as heavily modified, the scaling has to be modified, adapted to the special pressures causing the impact justifying the designation of hmw.
We refuse to assess heavily modified water bodies by comparing them with other heavily modified water bodies influenced by the same pressures. Doing so, it would be necessary to define in every surface water category and every water body type the maximal potential depending on the pressure type as a reference for scaling the assessment method. (e.g. medium sized River in ecoregion 9 modified by hydropower, or large river in ecoregion 14 modified due to navigation). Furthermore it would be necessary to define the stages of degradation for every specific constellation in the matrix formed by stream types and pressures. We consider this way of scaling the assessment method as not feasible!
8.1 Determining Maximum Ecological Potential and Comparison with Comparable Water Body
Waterbody 2 is characterized by 19.7 km stagnant water and 7.9 km free flowing river. So the representative status of this water body is stagnation due to impoundment. This section resembles most to rivers flowing through natural lakes. Under natural conditions these situation with alternation of water body categories only appears in the adjacent lowland area (ecoregion 14) but not in the mountainous area of ecoregion 9. So the carbonatic shallow lake of ecoregion 14 passed by a river flowing through, with mean exchange times between 3 to 30 days can't be used directly as new reference condition. So to assess the ecological potential, water body 2 will be compared to this special type of lake in the lowlands, but not species community will be used, because of differences in species community due to geographical differences in altitude and climate. Instead we suggest to use higher taxonomic groups e.g. family or genus, or summarizing parameters e.g. chlorophyll-a concentration. On this level case study Ruhr 75 waterbody 2 will be comparable to the shallow lowland lake with mean exchange time between 3 to 30 days. Assessed as natural water body the biological parameters fish community and macroinvertebrates were used. Now, treated as heavily modified water body belonging to the water body category "lake" the biological parameters macrophytes, phytoplankton and fish will be used. The macroinvertebrate community of a lake is of minor importance, not able to separate clearly different ecological conditions. Applying this method to water body 2 the maximum ecological potential can be defined:
• Fish community - stream continuum, enabling fish migration - Reference condition: under natural condition: barbel region, as heavily modified water body: fish community of the bream region, completed by species typical in the "moray- pike- tench-lake" (MÜLLER 1983). Species composition, abundance and age structure consist totally or nearly totally undisturbed conditions.
• Phytoplankton Under natural condition the River Ruhr (as an example of the stream type: mid-sized gravel bottom mountain stream (basement rock)) would be characterized by phosphorus concentrations (total phosphorus) less than 33 µg/l PO4-P (LUA 2001c). These concentrations are the regular input to the lake. Under this condition a eutrophic lake (KLAPPER 1992) or a mesotrophic to eutrophic lake (SCHWOERBEL 1993) will develop. Eutrophic lakes are characterized by Chlorophyll-a concentration ≤ 10 µg/l and a density of algae cells ≤ 10.000 cells/ml.
• Macrophytes Regarding the situation with a maximum ecological potential macrophyte communities of the Ranunculus-typ typical in large rivers in the mountainous region will be developed, associated with the vegetation type Myriophyllo-Nupharetum with submerse plants typical in eutrophic lakes (LUA 2001a, 2001 b).
case study Ruhr 76 9 Definition of Good Ecological Potential
9.1 Determination of Good Ecological Potential
In accordance with the definition of the maximum ecological potential (MEP) the good ecological potential (GEP) of waterbody 2 can be defined also using fish community, phytoplankton and macrophytes. • Fish community - stream continuum, enabling fish migration for most fish species, at least in the main migration period - Reference condition: fish community of the bream region, completed by species typical in the " moray- pike- tench – lake". The differences between high ecological status and good ecological status in this very lake type should be the same as it is between maximum ecological potential and good ecological potential.
Assessing the ecological potential the same methods are used as in assessing the ecological status. Because the assessment system of the European research project "FAME" still is not available, the method based on a survey by Gaumert will be used in the case study although this method should only be applied to running water (important: remarks in 10.1). Results: • in the lower Ruhr River all key-species of the lake type "moray- pike- tench – lake" are abundant as well as accompanying species ⇒ classification: very good (but regarding the fish fauna of the impounded Lake Kemnade only 57 % of these species were recorded in 2001 ⇒ classification: moderate) • anadromic and katadromic fish: rare => classification: poor • key-species moray (Anguilla anguilla) pike (Esox lucius) and tench (Tinca tinca): percentage in the impounded Lake Kemnade = 7.25 % => classification: good • Accompanying species: percentage 1 - > 10 % (= eudominant, dominant or recedent, some subrededent) => classification: good • Share of key-species and accompanying species = 92,75 % => classification: very good Conclusion: Using this method, the ecological potential indicated by the fish fauna can be assumed as good, but measures to enable more fish migration are essential (but the method does not fit to stagnant water; till now, no other method is available. And the age structure of the fish fauna was not used for assessment).
• Phytoplankton case study Ruhr 77 The catchment of the River Ruhr is partly densely populated; the non urbanized area is mainly used for agriculture. Due to this using pattern, the phosphorus load of the river is augmented. The actual concentration of total phosphorus upstream the lakes is 150 µg/l total phosphorus (90 percentile). In water body 2, designated as heavily modified, ortho-posphate concentrations up to 380 µg/l occur. More than 100 µg/l total phosphorus are accounted to be critical in lakes, pushing the water body towards hypertrophic conditions with the danger of system collapse (OECD 1982, KLAPPER 1992). So concentrations lower 100 µg/l total phosphorus are defined as targets situation, to guarantee a good ecological potential. Under this condition a eutrophic to polytrophic lake will develop. This limiting value is also used in the German state Brandenburg characterised by natural rapid flushed lakes situated in the continuum of rivers. In the German state Schleswig-Holstein the limited value for the concentration of total phosphorus is 300 µg/l, in the German states Saarland and Baden- Württemberg the limiting value is 150 µg/l (in Baden-Württemberg only in impounded lakes) (LAWA 1998). The water management association “Ruhrverband” strives for a total phosphorus concentration of less than 200 µg/l in the River Ruhr during the vegetation period (NUSCH 1982). Eutrophic to polytrophic lakes are characterized by Chlorophyll-a concentration ≤ 30 µg/l (KLAPPER 1992). In the German state Mecklenburg-Vorpommern the limiting value of the Chlorophyll-a concentration is 50 mg/l, in the German state Brandenburg the limiting value is 80 µg/l (LAWA 1998). The water management association “Ruhrverband” wants to reduce the Chlorophyll-a concentration in 95% of the year to a concentration less than 60 µg/l (NUSCH 1982). So actually maximum concentrations up to 24.3 µg/l appear in water body 2, during 90 % of the year the concentration is less than 11.8 µg/l (RUHRVERBAND 2001a). Conclusion: Regarding the nutrient concentration and the resulting phytoplankton community in water body 2 the phosphorus concentration exceeds the limiting value of 100 µg/l, but the resulting phytoplankton density with concentrations less than 30 µg/l achieves a good ecological potential. This can be explained by the synergistic effect of the five impounded lakes working together as one stagnant system (NUSCH 1982). Summarizing the retention times of all this lakes, the effects of augmented phosphorus concentration evokes algal blooms, exceeding the limiting value of Chlorophyll-a concentration several times. But these hypertrophic conditions only appear in the lakes downstream waterbody 1 (Kettwiger Stausee, Baldeneysee). These lakes, not considered here in detail, because outside the core region of this case study, probably will be heavily modified as well as water body 2. But in contrast to water body 2, in Kettwiger Stausee and Baldeneysee there is no good ecological potential due to hypertrophic conditions with algal blooms in summer.
• Macrophytes Macrophyte communities are not able to separate between high and good ecological status under national conditions (LUA 2001a). So, also in case of heavily modified water bodies there will be no difference between maximum and good ecological status. So in waterbody 2 also in the quality class of good ecological potential the macrophyte community of the Ranunculus- typ typical in large rivers in the mountainous region, associated with the vegetation type Myriophyllo-Nupharetum with submerse plants typical in eutrophic lakes should be developed.
case study Ruhr 78 9.2 Identification of Measures for Protecting and Enhancing the Ecological Quality The measures and costs are already discussed in 7.4.3.
case study Ruhr 79 PART III
case study Ruhr 80 10 Conclusions, Options and Recommendations
On the whole, the method to identify and designate heavily modified water bodies described in hmwb papers 1 – 12 is working well. But we suggest to change the order of sub-chapters in chapter 4 beginning with the identification of water bodies (4.3) followed by the description of geology, topography and hydrology (4.1) and socio-economic, geography, and human activities in the catchment of the water body (4.2), because these characteristics can be different in every water body. Due to the fact that we started with our case studies not until September 2001, we were not able to get all the data necessary to evaluate the ecological status as well as the data necessary for socio-economic analysis. For this reason we used a poor data base to assess the ecological status / potential and we had to make some rough calculations. In future this must be done more precisely and this will take more time. Probably additional investigations on biological quality elements as well as more detailed information on the characteristics of the catchment and the intensity of human uses will be necessary. In the designation and identification process on hmwb, it was a great problem, that till now for most of the biological quality elements, assessment methods in accordance to the WFD are missing. We were able to use the new European assessment method AQEM based on macroinvertebrates, which assess the ecological status of natural water bodies. By changing the reference definition, this method can also be used to determinate the ecological potential of heavily modified water bodies. So this method seems to be a very useful tool. Regarding the fish fauna, a preliminary assessment method published by Gaumert was used. This shouldn't be done in future, because the method does not consider the stream type and until now, the method is not calibrated on other stream orders or regional stream types. But the method of Gaumert is also a multimetric method like the methods of the European research project FAME (in preparation) and the German assessment method on the ecological status based on the fish fauna (in preparation). So we used the method by Gaumert as a placeholder 'till the methods mentioned above, are available. We did this only to show how we think the designation process should be done in future, aware that probably the results using the method of Gaumert will be different from the assessment results by the method of FAME or by the German method.
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case study Ruhr 84 Annex Fish fauna of the lower Ruhr River, free flowing sections (25 sampling stations)
Standard- ∅ N abweichung Aal 38,4 36,3 Äsche 0 Bachforelle 0,04 0,2 Barbe 0,04 0,2 Barsch 26,5 31,4 Brasse 6,6 8,9 Döbel 23,1 22,6 Elritze 0 Gründling 66,8 236,9 Güster 0,5 1,3 Hasel 1,1 2,3 Hecht 0,8 2,2 Karausche 0,04 0,2 Karpfen 0,9 3,2 Kaulbarsch 3,7 7,6 Rotauge 57,0 114,1 Schleie 2,3 5,8 Schmerle 0,1 0,3 Ukelei 12,8 55,9 Zander 1,4 2,4 Fish fauna of the impounded lake Kemnader Stausee (April 2001) Art N Aal 17 Barsch 3 Brasse 145 Döbel 10 Güster 1 Aland Hybride 2 Hecht 2 Karausche 0 Karpfen 3 Rotauge 79 Rotfeder 0 Schleie 0
case study Ruhr 85 Species composition and abundance (ind/m²) at gravel banks in the middle Ruhr River (NH = Neheim) and the lower Ruhr River (MH = Mülheim) in 2000/2001 MH NH ARTNAME Sommer MH Winter Sommer NH Winter Dugesia lugubris (SCHMIDT) 39 6 Dendrocoelum lacteum (MÜLLER) 21 Valvata piscinalis MÜLLER 87 18 Valvata cristata 3 231 Potamopyrgus jenkinsi SMITH 15 18 3 Bithynia tentaculata L. 6 36 Physa acuta DRAPARNAUD 9 Radix spec. 12 27 12 27 Anisus sp. 3 9 Gyraulus albus MÜLLER 42 87 Ancylus fluviatilis MÜLLER 9 153 108 351 Acroloxus lacustris L. 6 Dreissena polymorpha 39 51 Pisidium spec. 132 363 3 54 Sphaerium corneum L. 3 6 Lumbriculus variegatus (MÜLL.) 159 69 543 810 Stylodrilus heringianus CLAP. 207 192 Lumbriculidae non det. 174 Tubificidae non det. 12 3 456 246 Naididae non det. 489 Oligochaeta non det. 12 81 204 348 Glossiphonia complanata (L.) 6 3 Glossiphonia heteroclita (L.) 3 18 3 Glossiphonia spec. 3 Helobdella stagnalis (L.) 369 81 Hemiclepsis marginata 15 6 Erpobdella octoculata (L.) 24 12 57 54 Erpobdella nigricollis 24 Erpobdellidae non det. 9 21 36 45 Ostracoda non det. 72 45 96 18 Asellus aquaticus L. 1320 262 6 Echinogammarus berilloni (CATTA) 1251 1575 Gammarus pulex L. 3 33 Dikerogammarus villosus 426 9 Gammaridae non det. 273 3 300 141 Baetis fuscatus (L.) 30 Baetis rhodani PICT. 3 27 Baetis spec. 12 Baetidae non det. 3 60 9 Ecdyonurus spec. 3 Ephemerella ignita PODA 3 Torleya major (KLAP.) 3 Caenis horaria L. 333 162 6 Caenis luctuosa BURM. 1302 624 30 105 Caenis macrura 126 Caenis spec. 669 300 1380 1041 Habroleptoides confusa SARTORI & JACOB 6 Ephemera danica MÜLL. 6
case study Ruhr 86 Species composition and abundance (ind/m²) at gravel banks in the middle Ruhr River (NH = Neheim) and the lower Ruhr River (MH = Mülheim) in 2000/2001 MH NH ARTNAME Sommer MH Winter Sommer NH Winter Ephemeroptera non det. 36 Orectochilus villosus MÜLLER 9 Platambus maculatus (L.) 24 Elmis spec. 39 207 Limnius spec. 222 177 Coleoptera non det. 12 Sialis spec. 6 Rhyacophila nubila (ZETT.) 15 Agapetus spec. 3 Agraylea multipunctata 3 Hydroptila spec. 12 Hydropsyche incognita 69 Hydropsyche siltalai DÖHLER 132 Hydropsyche spec. 15 Polycentropus flavomaculatus PICTET 21 147 Polycentropodidae non det. 6 Psychomyia pusilla (FABRICIUS) 33 Tinodes waeneri L. 3 Tinodes spec. 3 Ecnomus tenellus 9 Allogamus auricollis 3 Limnephilidae non det. 6 Lepidostoma hirtum FBR. 693 Athripsodes spec. 9 63 435 Mystacides azurea (L.) 27 3 9 Mystacides spec. 9 Oecetis ochracea CURTIS 9 Oecetis spec. 6 21 Leptoceridae non det. 3 Sericostoma flavicorne/personatum 12 69 Trichoptera non det. 15 36 9 Antocha spec. 6 12 207 Dicranota spec. 1 36 Psychodidae non det. 6 Simulium ornatum (MG.) 15 Simulium spec. 21 Simuliidae non det. 1 Tanypodinae non det. 60 18 54 201 Orthocladiinae non det. 1071 456 768 2358 Tanytarsini non det. 384 249 879 2370 Chironomini non det. 3057 1962 6921 2874 Chironomidae non det. 1086 186 441 375 Bezzia spec. 48 42 411 Empididae non det. 3 6 Atherix ibis F. 6 Diptera non det. 6 12
case study Ruhr 87 Results of the AQEM-assessment at gravel banks in the middle Ruhr River (NH = Neheim) and the lower Ruhr River (MH = Mülheim) in 2000/2001 MH NH Metrics Sommer MH Winter Sommer NH Winter Abundance [Ind./m²] 11181 5723 14569 16635 number of taxa 41 46 48 54
Saprobic Index (Zelinka & Marvan) 2,47 2,36 2,32 2,03 Saprobic Valence (Zelinka & Marvan; percentage of community) xeno [%] 0,05 0,42 0,22 0,33 oligo [%] 1,25 3,03 0,96 3,45 beta-meso [%] 18,70 16,40 2,94 8,20 alpha-meso [%] 15,75 12,40 2,58 4,54 poly [%] 1,76 0,85 0,50 0,58 no data available 62,49 66,91 92,79 82,90
German Saprobic Index (DIN 38 410) 2,37 2,33 2,33 2,05 Measure of dispersion ('Streuungsmaß') 0,08 0,08 0,12 0,09 Measure of abundance ('Abundanzziffer') 51,00 45,00 33,00 59,00 Number of indicator taxa 14,00 13,00 11,00 16,00 Water quality class II-III II-III II-III II
Dutch Saprobic Index 0,98 0,77 0,17 0,35
BMWP (Biological Monitoring Working Party) 82,00 80,00 116,00 157,00 ASPT (Average Score per Taxon) 4,10 4,44 5,29 6,04
BMWP (Spain) 76,00 74,00 109,00 165,00
DSFI (Danish Stream Fauna Index) 3,00 3,00 5,00 7,00 Diversity Groups 1,00 -4,00 5,00 10,00 BBI (Belgian Biotic Index) 9,00 8,00 9,00 9,00
IBE 10,00 9,00 9,60 12,00 Quality Class 1,00 2,00 1,30 1,00 Systematic Units 28,00 24,00 26,00 33,00 IBE AQEM 10,00 9,00 9,60 12,00 Quality Class 1,00 2,00 1,30 1,00 MAS 2,00 2,00 2,33 2,60 Integrity class 5,00 5,00 3,00 3,00 Operational Units 2,00 2,00 6,00 5,00 MTS 4,00 4,00 14,00 13,00 MAS (large river) 2,00 2,00 2,33 2,60 Integrity class 5,00 5,00 3,00 3,00 Operational Units 2,00 2,00 6,00 5,00 MTS 4,00 4,00 14,00 13,00
case study Ruhr 88 MH NH Metrics Sommer MH Winter Sommer NH Winter diversity (Simpson-Index) 0,87 0,85 0,75 0,91 diversity (Shannon-Wiener-Index) 2,45 2,54 2,10 2,82 evenness 0,66 0,66 0,54 0,71
Acid class (according to Braukmann) acid class 2 acid class 1 acid class 1 acid class 1 Share acid class 1 (no acidification) 9,43 32,60 34,31 39,18 Share acid class 2 (periodical slight acidification) 90,57 67,23 8,03 35,42 Share acid class 2 (periodical serious acidification) 0,00 0,00 5,84 0,00 Share acid class 1 (permanent acidification) 0,00 0,17 51,82 25,39
Zonation (percentage of community preferring a certain zone) crenal (spring) [%] 0,17 0,14 0,41 0,52 hypocrenal (spring-brook) [%] 0,25 0,59 0,74 1,13 epirhithral (upper-trout region) [%] 2,41 1,64 1,14 1,73 metarhithral (lower-trout region) [%] 3,95 2,90 2,25 5,87 hyporhithral (greyling region) [%] 5,67 4,47 2,48 6,02 epipotamal (barbel region) [%] 9,76 7,37 3,28 4,50 metapotamal (brass region) [%] 7,20 4,83 2,65 3,20 hypopotamal (brackish water) [%] 4,47 2,71 2,54 2,90 Litoral [%] 12,37 11,72 3,84 4,00 Profundal [%] 2,18 0,89 0,92 0,62 no data available [%] 51,57 62,75 79,76 69,50
Current preference (percentage of community preferring a certain current) Type LB (limnobiont, occurring only in standing waters) [%] 0,00 0,00 0,00 0,00 Type LP (limnophil, preferably occurring in standing waters; avoids current; rarely found in slowly flowing streams) [%] 4,43 4,14 3,77 4,87 Type LR (limno- to rheophil, preferably occurring in standing waters but regularly occurring in slowly flowing streams) [%] 2,52 8,60 0,99 2,76 Type RL (rheo- to limnophil, usually found in streams; prefers slowly flowing streams and lentic zones; also found in standing waters) [%] 0,03 0,07 10,89 16,16 Type RP (rheophil, occurring in streams; prefers zones with moderate to high current) [%] 0,00 0,00 2,17 4,00 Metrics MH MH Winter NH NH Winter case study Ruhr 89 Sommer Sommer Type RB (rheobiont, occurring in streams; bound to zones with high current) [%] 0,08 2,67 0,74 2,92 Type IN (indifferent, no preference for a certain current velocity) [%] 29,03 25,60 0,70 1,30 no data available [%] 63,91 58,92 80,74 67,99
Microhabitat preference (percentage of community preferring a certain microhabitat) Type Pel (Pelal: mud; grain size < 0.063 mm) [%] 16,58 15,57 15,44 8,56 Type Arg (Argyllal: silt, loam, clay; grain size < 0.063 mm) [%] 2,63 2,48 0,05 0,29 Type Psa (Psammal: sand; grain size 0.063-2 mm) [%] 24,10 30,68 36,21 15,56 Type Aka (Akal: fine to medium- sized gravel; grain size 0.2-2 cm) [%] 2,46 2,57 1,24 1,60 Type Lit (Lithal: coarse gravel, stones, boulders; grain size > 2 cm) [%] 12,25 12,50 5,67 16,25 Type Phy (Phytal: algae, mosses and macrophytes including living parts of terrestrial plants) [%] 16,37 13,66 13,00 21,16 Type POM (particulate organic matter, such as woody debris, CPOM, FPOM) [%] 5,82 4,98 6,20 7,10 Type Oth (other habitats) [%] 2,06 1,11 0,65 0,50 no data available [%] 17,74 16,46 21,54 28,98
Feeding types (percentage of community) Grazer and scrapers [%] 8,28 12,11 4,67 11,92 Miners [%] 0,97 0,33 0,34 0,23 Xylophagous taxa [%] 0,01 0,00 0,00 1,25 Shredders [%] 4,59 2,25 4,76 7,47 Gatherers/Collectors [%] 67,45 67,06 78,93 55,90 Active filter feeders [%] 3,50 8,25 0,63 0,84 Passive filter feeders [%] 0,00 0,03 0,03 0,98 Predators [%] 6,84 4,59 1,90 6,03 Parasites [%] 1,11 0,43 0,30 0,23 Other Feeding Types [%] 0,92 0,44 0,01 0,01 no data available [%] 6,33 4,51 8,44 15,15
RETI (Rhithron Feeding Type Index) 0,15 0,16 0,11 0,26
case study Ruhr 90 MH NH Metrics Sommer MH Winter Sommer NH Winter Locomotion type (percentage of community) Swiming/skating [%] 0,03 0,09 0,00 0,01 Swimming/diving [%] 7,22 3,09 1,46 2,03 Burrowing/boring [%] 0,82 1,91 4,11 3,24 Sprawling/walking [%] 16,58 20,27 8,02 11,13 (Semi)sessil [%] 4,96 5,51 1,23 1,25 Others (e.g. climbing) [%] 21,50 17,66 6,19 4,66 no data available [%] 48,89 51,48 78,99 77,67 Chironomidae [%] 50,60 50,17 62,21 49,16 Order (percentage of community) Porifera [%] 0,00 0,00 0,00 0,00 Coelenterata [%] 0,00 0,00 0,00 0,00 Cestoda [%] 0,00 0,00 0,00 0,00 Trematoda [%] 0,00 0,00 0,00 0,00 Turbellaria [%] 0,54 0,10 0,00 0,00 Nematoda [%] 0,00 0,00 0,00 0,00 Nematomorpha [%] 0,00 0,00 0,00 0,00 Gastropoda [%] 1,64 10,12 0,84 2,33 Bivalvia [%] 1,53 7,29 0,02 0,36 Polychaeta [%] 0,00 0,00 0,00 0,00 Oligochaeta [%] 1,64 2,67 10,87 12,53 Hirudinea [%] 4,02 2,41 0,68 0,61 Crustacea [%] 18,70 5,57 11,37 10,62 Araneae [%] 0,00 0,00 0,00 0,00 Ephemeroptera [%] 20,96 18,98 10,48 7,95 Odonata [%] 0,00 0,00 0,00 0,00 Plecoptera [%] 0,00 0,00 0,00 0,00 Heteroptera [%] 0,00 0,00 0,00 0,00 Planipennia [%] 0,00 0,00 0,00 0,00 Megaloptera [%] 0,00 0,00 0,04 0,00 Trichoptera [%] 0,21 1,57 1,07 9,85 Lepidoptera [%] 0,00 0,00 0,00 0,00 Coleoptera [%] 0,11 0,00 1,96 2,36 Diptera [%] 50,66 51,28 62,67 53,38 Bryozoa [%] 0,00 0,00 0,00 0,00 Hydracarina [%] 0,00 0,00 0,00 0,00 EPT-Taxa [%] 21,17 20,55 11,55 17,80
Order (number of taxa) Porifera 0,00 0,00 0,00 0,00 Coelenterata 0,00 0,00 0,00 0,00 Cestoda 0,00 0,00 0,00 0,00 Trematoda 0,00 0,00 0,00 0,00 Turbellaria 2,00 1,00 0,00 0,00 Nematoda 0,00 0,00 0,00 0,00 Nematomorpha 0,00 0,00 0,00 0,00 case study Ruhr 91 MH NH Metrics Sommer MH Winter Sommer NH Winter Gastropoda 8,00 9,00 3,00 3,00 Bivalvia 2,00 3,00 1,00 2,00 Polychaeta 0,00 0,00 0,00 0,00 Oligochaeta 3,00 3,00 5,00 5,00 Hirudinea 7,00 5,00 4,00 3,00 Crustacea 4,00 4,00 5,00 4,00 Araneae 0,00 0,00 0,00 0,00 Ephemeroptera 5,00 3,00 9,00 8,00 Odonata 0,00 0,00 0,00 0,00 Plecoptera 0,00 0,00 0,00 0,00 Heteroptera 0,00 0,00 0,00 0,00 Planipennia 0,00 0,00 0,00 0,00 Megaloptera 0,00 0,00 1,00 0,00 Trichoptera 3,00 8,00 8,00 14,00 Lepidoptera 0,00 0,00 0,00 0,00 Coleoptera 1,00 0,00 3,00 3,00 Diptera 6,00 10,00 9,00 12,00 Bryozoa 0,00 0,00 0,00 0,00 Hydracarina 0,00 0,00 0,00 0,00 EPT-Taxa 8,00 11,00 17,00 22,00
case study Ruhr 92