Water Framework Directive : Heavily Modified Water Bodies
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Revised Terms of Reference [28/11/2000] Heavily Modified Waters in Europe Case Study on the River Lagan, the Tidal Lagan Transitional Water & the Port of Belfast Coastal Water, Northern Ireland Peter Hale, David Corbelli, Claire Vincent (Environment and Heritage Service) Meg Postle, Teresa Fenn, John Ash (Risk & Policy Analysts) Environment and Heritage Service Risk & Policy Analysts 17 Antrim Road Farthing Green House LISBURN Beccles Road BT28 3AL Loddon 00 44 2890 254754 – phone Norfolk 00 44 2890 254761 - fax NR14 6LT Tel: +44 1508 528465 Table of Contents page PART I 4 1 Preface [to be drafted by project managers] (1 page) 5 2 Summary Table (2 pages) 1 3 Introduction (2 pages) 1 3.1 Choice of Case Study 1 3.2 General Remarks 1 4 Description of Case Study Area (3 pages) 3 4.1 Geology, Topography and Hydrology 3 4.2 Socio-Economic Geography and Human Activities in the Catchment 3 4.3 Identification of Water Bodies 4 4.4 Discussion and Conclusions 10 PART II 11 5 Physical Alterations (5 pages) 12 5.1 Pressures and Uses 12 5.2 Physical Alterations 13 5.3 Changes in the Hydromorphological Characteristics of the Water Bodies and Assessment of Resulting Impacts 15 5.4 Discussion and Conclusions 16 6 Ecological Status (7 pages) 18 6.1 Biological Quality Elements 18 6.2 Physico-Chemical Elements 27 6.3 Definition of Current Ecological Status 28 6.4 Discussion and Conclusions 29 7 Identification and Designation of Water Bodies as Heavily Modified (6 pages) 30 7.1 Necessary Hydromorphological Changes to Achieve Good Ecological StatusFehler! Textmarke nicht definiert. 7.2 Assessment of Other Environmental OptionsFehler! Textmarke nicht definiert. 7.3 Designation of Heavily Modified Water BodiesFehler! Textmarke nicht definiert. 7.4 Discussion and Conclusions 39 8 Definition of Maximum Ecological Potential (6 pages) 1 8.1 Determining Maximum Ecological Potential 1 8.2 Measures for Achieving MEP 3 8.3 Comparison with Comparable Water Body 5 8.4 Discussion and Conclusions 5 9 Definition of Good Ecological Potential (6 pages) 6 9.1 Determination of Good Ecological Potential 6 9.2 Identification of Measures for Protecting and Enhancing the Ecological Quality 6 9.2.1 Basic Measures 6 9.2.2 Supplementary Measures 6 9.3 Discussion and Conclusions 6 PART III 7 10 Conclusions, Options and Recommendations (5 pages) 8 10.1 Conclusions 8 10.2 Options and Recommendations 8 2 11 Bibliography 9 12 List of Annexes 10 _______________________________________________________________ List of Tables, Boxes, Maps etc. page Table 1 [model heading for a table] Fehler! Textmarke nicht definiert. Box 1 [model heading for a box or map] Fehler! Textmarke nicht definiert. Table 2 [Details on separate groups of water bodies] 9 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) [insert the summary table on the case study already provided; "Annex IV" of the minutes of the kick-off meeting of the European project on heavily modified water bodies.] Item Unit Information 1. Country UK Northern Ireland 2. Name of the case study (name of water body) Lagan 3. Steering Committee member(s) responsible for the case MM David Corbelli study 4. Institution funding the case study EHS Environment and Heritage Service 5. Institution carrying out the case study EHS Environment and Service 6. Start of the work on the case study Sept. 2001 7. Description of pressures & impacts expected by Date Feb 2002 8. Estimated date for final results Date April 2002 9. Type of Water (river, lake, AWB, freshwater) text River, transitionlal water and coastal water (Port) 10. Catchment area 609 km2 11. Length/Size 70 km 12. Mean discharge/volume m3/s or m3 13. Population in catchment number 450 000 14. Population density Inh./km2 15. Modifications: Physical Pressures / Agricultural influences text 16. Impacts? text 17. Problems? text 18. Environmental Pressures? text 19. What actions/alterations are planned? text 20. Additional Information text 21. What information / data is available? text 22. What type of sub-group would you find helpful? text 23. Additional Comments text 2 3 Introduction (2 pages) 3.1 Choice of Case Study The Lagan catchment is the most densely populated in Northern Ireland and not only encompasses the city of Belfast with its economic and commercial centre, but also drains some of the most productive agricultural land in Northern Ireland. Industrial and urban development over the last 2 centuries have caused a severe deterioration in water quality in the lower reaches of the Lagan. In the last few years, there has been a large investment programme in the sewage treatment systems, and a decline in traditional industrial activity. Realistic water quality targets, robust routine monitoring and classification systems are now in place to ensure that the water quality within the catchment is maintained and, where necessary, enhanced. The Lagan is subject to a variety of physical pressures due to the level of urbanisation in the lower part of the catchment which has resulted in physical modification both historic for industrial purposes and current for flood defence and navigation. In the flood plain of the catchment there are pressures arising from the agricultural land use and the provision of flood defence. Recent proposals have suggested the reinstatement of the Lagan canal system. The whole area is a good example of a system with several pressures and future management and development issues. 3.2 General Remarks Five water bodies have been identified within the study area, these have been defined on physical criteria that represent changes in energy and physical structure. Water bodies defined are also based on the pressures upon them and have in some cases been subdivided further to facilitate management options. The case study focuses on a number of pressures (flood defence, land drainage, land take and navigation). This study will contribute to the navigation subgroup and the flood defence subgroup (once it has been established). Figure 1 – Case study area and water bodies identified Figure 1 - Case Study Area and Water Bodies identified River Netw orks Identif ied Zones wit hin Lagan Catchm en t Zon e 5 - Harbour Area Zon e 4 - Im pound men t Zon e 3 - F lo odplain Zon e 2 - Middl e Reaches Zon e 1 - Up lan d Lagan Catchm en t 0 5 10 15 Kilome tres N 2 4 Description of Case Study Area (3 pages) 4.1 Geology, Topography and Hydrology Geology The Lagan catchment overlies the Triassic Sherwood Sandstone aquifer, which at present is used as a small water supply. In the future, however, this may become an important public water supply as industrial and population demands grow. The source of recharge to the aquifer is not fully understood, but it is believed that infiltration occurs along the valley margin and in the Antrim Hills. Sands and gravels in the lower end of the catchment may contribute to river base flows. Much of the catchment is underlain by greywackes and mudstones, with a sandstone deposit following the river valley below Waringstown. As a result of glacially induced erosion, the catchment is covered in “drift”, generally comprising till or boulder clay. Although peatlands are prevalent over much of Ireland, only a small fraction of the Lagan catchment is covered in peat. Figure 2 – Solid geology of the Lagan catchment Figure 2 - Solid Geology of the Lagan catchment AR G IL LA C EO U S R O C K S AN D [S U B EQ U A L/S U BO RD IN A TE] LIM ES TO N E , IN TE R BE D D ED AR G IL LA C EO U S R O C K S W ITH SU B O R D IN ATE S AN D S TO N E AN D E VA PO R I TIC R O C KS AR G IL LA C EO U S R O C K S , U N DIF FE RE N TIA TE D BA S AL T 1E C 0 CH A LK A N D SA ND S TO N E DO L E RIT E 1E B 0 FE LSI TE G RA N O D IO R ITE 1AA C LA M P RO P H YR E G R O U P 1G 00 M U DS T O NE 3S 00 RH Y O LIT E 1B A A SA N D STO N E 3D 00 SA N D STO N E A ND S U B O RD IN A TE B R EC C IA 0 5 10 15 Kil om e tre s N Topography The Lagan catchment covers an area of 609 km2. The River Lagan rises as a spring on Slieve Croob 30km to the south-west of Belfast, the River being some 70km in length. The "U" shape of the Lagan Valley is characteristic of glacial action and the river itself has had little impact on the overall shape of the valley. For the first few kilometres, the Lagan falls steeply through mountain pastures and quickly develops a meandering character with a shingle bed (water body 1). Below Drummiller the river falls steadily until Magheralin (water body 2), where the gradient 3 reduces and the river becomes sluggish, encouraging weed growth (water body 3a).