Heavily Modified Waters in Europe Case Study on the River “Zwickauer Mulde”1 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] 1 The Saxon State Ministry of Environment and Agriculture kindly gave the permission to use data in this case study analysis. The data were provided by the Saxon State Agency of Environment and Geology and the Saxon State Agency of Agriculture. 1 Members of the research project MAKEF (co-authors) • Dr. P. Podraza University of Essen Institute of Ecology, Department of Hydrobiology D-45117 Essen • Prof. Dr. Klaus Greve Rheinische Friedrich-Wilhelms-Universität Bonn, Institute of Geography D-53115 Bonn • Martin Halle umweltbüro essen A. Bolle & Partner GbR Rellinghauser Str. 334 f D-45136 Essen • Dr. Thomas Zumbroich, Dr. Andreas Müller Büro für Umweltanalytik Bonn/ Essen Breite Str. 21 D-53111 Bonn • Dirk Glacer Ingenieurbüro Glacer Horster Str. 25e D-45279 Essen 2 Table of Contents page PART I 5 1 Preface 6 2 Summary Table 7 3 Introduction 8 3.1 Choice of Case Study 8 3.2 General Remarks 8 4 Description of Case Study Area 9 4.1 Geology, Topography and Hydrology 9 4.2 Socio-Economic Geography and Human Activities in the catchment 11 4.3 Identification of Water Bodies 13 4.4 Discussion and Conclusions 19 PART II 20 5 Physical Alterations 21 5.1 Pressures and Uses 21 5.2 Physical Alterations 29 5.3 Changes in the Hydromorphological Characteristics of the Water Bodies and Assessment of Resulting Impacts 32 5.4 iscussion and Conclusions 32 6 Ecological Status 33 6.1 Biological Quality Elements 33 6.1.1 Macroinvertebrates 33 6.1.2 Fish fauna 36 6.2 Physico-Chemical Elements 39 6.3 Definition of Current Ecological Status 41 6.4 Discussion and Conclusions 44 7 Identification and Designation of Water Bodies as Heavily Modified 45 7.1 Provisional identification of HMWB 45 7.2 Necessary Hydromorphological Changes to Achieve Good Ecological Status 45 7.3 Assessment of Other Environmental Options 48 7.4 Designation of Heavily Modified Water Bodies 48 8 Definition of Maximum Ecological Potential 49 9 Definition of Good Ecological Potential 50 PART III 51 10 Conclusions, Options and Recommendations 52 10.1 Conclusions 52 10.2 Options and Recommendations 52 11 Bibliography 53 _______________________________________________________________ 3 List of Tables, Boxes, Maps etc. Figures: page Fig. 1: Case study area with important cities and river network. 9 Fig. 2: Water flow classification 10 Fig. 3: Altitudinal relief of case study area 11 Fig. 4: Population density in administrative districts of the Zwickauer Mulde catchment. 13 Fig. 5: Water bodies in the Case study Area 15 Fig. 6: Land use distribution in case study area 24 Fig. 7: River Habitat Survey and Artificial Barriers from km 63 to km 97. 30 Fig. 8: River Habitat Survey and Artificial Barriers from km 97 to km 122 31 Fig. 9: Fish habitat zones of the river Zwickauer Mulde 36 Fig. 10: Ecological status– Evaluation of Fish Fauna 42 Fig. 11: Ecological status– Evaluation of Macroinvertebrate Fauna 43 Fig. 12: Ecological status– Overall Evaluation 44 Tables: Tab. 1: Summary Table 7 Tab. 2: Population of administrative districts 12 Tab. 3: Land use distribution 12 Tab. 4: Identification of Water Bodies 14 Tab. 5: Water bodies in Case study Area 14 Tab. 6: Description of Water bodies in Case study Area 16 Tab. 7: Pressures and Uses in the Case study Area 21 Tab. 8: Flood protection dams in the case study area 22 Tab. 9: Criteria for the identification of significant pressures on surface-waters 25 Tab. 10: Identification of significant pressures on water bodies of the river Zwickauer Mulde 28 Tab. 11: Survey on saprobic water quality classes 33 Tab. 12: Improvement of water quality at the Zwickauer Mulde river 34 Tab. 13: Metrics (Summer 2000) 34 Tab. 14: Metrics (Autumn 2000) 35 Tab. 15: Pre-classification (Summer 2000) 35 Tab. 16: Pre-classification (Autumn 2000) 35 Tab. 17: Classification (Summer 2000) 35 Tab. 18: Classification (Autumn 2000) 36 Tab. 19: Historical and recent fish communities in the River Zwickauer Mulde 37 Tab. 20: Water quality at the gauges Niederschlema und Sermuth (1995) 40 Tab. 21: Physico-chemical water quality at Wiesenburg water works (1997) 41 Tab. 22: Description of ecological status based on faunistic data 42 Tab. 23: Provisional identification of heavily modified water bodies 45 Tab. 24: Summary of measures to achieve good ecological status 47 4 PART I 5 1 Preface Within the scope of the European project "Identification and Designation of Heavily Modified Water Bodies under the Water Framework Directive" 25 Case Studies in eleven member states are realised. The aim is the development of assessment criteria for the designation of heavily modified water bodies in contrast to natural surface waters. As the normative definitions of heavily modified waters in the Water Framework Directive are widely interpretable, and the quality requirements for heavily modified waters are minor compared to natural surface waters, the project is dealing with the determination of uniform quality levels to be implemented in Europe. Thus, the approach includes the assessment of the ecological situation and the specification of quality targets ("high status" for natural waters respective "maximum ecological potential" for heavily modified waters). To identify measures to improve the ecological situation and finally to achieve the given quality target Germany investigates case studies in the river basins Elbe, Lahn, Seefelder Aach Ruhr, Zwickauer Mulde and Dhünn. 6 2 Summary Table Tab. 1: Summary Table Item Unit Information 1. Country text Germany 2. Name of the case study (name of text Zwickauer Mulde (Elbe catchment) water body) 3. Steering Committee member(s) text Dr. Ulrich Irmer, Dr. Bettina Rechenberg, German responsible for the case study Federal 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 Bonn/Essen, Büro Glacer Essen 6. Start of the work on the case study Date 01.09.2001 7. Description of pressures & impacts Date expected by 8. Estimated date for final results Date 31.03.2002 9. Type of Water (river, lake, AWB, text river freshwater) 10. Catchment area km2 964 km² (investigation area), 2107 km² (Zwickauer Mulde) 11. Length km 65 km (investigation area), 167 km (Zwickauer Mulde) 12. Mean discharge m3/s 28,9 (gauge Wechselburg 1) 13. Population in catchment number 794.500 14. Population density Inh./km² 381 Inh./km² mean (min: 153 Inh./km², max. 1005 Inh./km²) 15. Modifications: Physical Pressures / Agri- text Hydropower generation, water supply, flood protection, cultural influences intense agriculture, historical ore mining 16. Impacts? text Disruption of water organism migration paths by dams and weirs, 17. Problems? text Heavy metal pollution, water flow disruption, 18. Enviromental Pressures? text Urbanisation, agriculture and forestry 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 availiable? text - land use patterns - data on water chemistry and discharge - German Water Quality Survey, - German River Habitat Survey, 22. What type of sub-group would you find text helpful? 23. Additional Comments text 7 3 Introduction 3.1 Choice of Case Study The research area was chosen as a case study object for several reasons: • The catchment of the River Zwickauer Mulde represents several different stream types in different landscape areas (= different reference conditions). • The River Zwickauer Mulde represents rivers in historically industrialised areas. The multiplicity of different pressures and impacts increases the probability of a designation as heavily modified waterbody. • Due to several previous research projects on water quality, morphological status and special problems of heavy metal and radioactive pollution a sufficient amount of recent data are available. • 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 waterbodies in the catchment areas of Ruhr and Mulde. 3.2 General Remarks The river Zwickauer Mulde unites with the river Freiberger Mulde to form the Vereinigte Mulde, an important tributary of the River Elbe. The relevant uses within the catchment are: • Water supply Several reservoirs for water supply have been constructed. Most recently the reservoir „Eibenstock“ (upper bound of the research area) started operation in 1983. • Urbanisation The river Zwickauer Mulde flows within a broad valley, agriculturally used for grassland. The city of Zwickau is one of the urban centres along the river Zwickauer Mulde. • Hydropower generation In the research area several hydropower plants are under operation. The corresponding weirs, as well as those of historical power plants no longer operating, disrupt the river continuum. 8 4 Description of Case Study Area 4.1 Geology, Topography and Hydrology The river Zwickauer Mulde originates in the mountainous region "Westerzgebirge" at 762 m above sea level, north east of the city Klingenthal. After a flow length of 166 km it unites with the river Freiberger Mulde, forming the „Vereinigte Mulde“, a major tributary of the river Elbe, at 132 m above sea level. Flöha Chemnitz Zwickauer Mulde N Chemnitz Flöha Würschnitz Zwickau Zwönitz Zschopau Legend: 01020KilometersUrban Area Case Study Area Fig. 1: Case study area with important cities and river network. A typical river of low mountain range, the river Zwickauer Mulde is in flood in springtime as well as in autumn.