FINAL REPORT FOR TASK 1A.3 RESTORING NATURAL VALUES OF LOWER ODRA VALLEY BY IMPROVING RETENTION AND FLOOD PROTECTION CAPACITIES OF MIĘDZYODRZE
State Water Holding Polish Water, Catchment Management Board in Szczecin Teofila Firlika 19, 71-637 Szczecin
ODRA AND VISTULA FLOOD PROTECTION PROJECT Task 5.3 .: Design and Construction Supervision for works, Project Management, Technical Assistance and Training Technical Support for the Project and Strengthening of PIU’s Institutional Capacity.
prepared by:
JOINT VENTURE
Consortium Leader Sweco Consulting Sp. z o. o. ul. Franklin Roosevelt 22 60-829 Poznań Dictionary of abbreviation
NO. ABBREVIATION NAME
1 Joint Venture (JV) consists of: Consultant, Sweco Consulting Sp. z o. o. - JV Leader Engineer, Consultant Sweco Engineering Sp. z o. o. - JV Partner Engineer, IK Ekocentrum - Wrocławski Ośrodek Usług Ekologiczne Sp. z o. o. - JV subcontractor consultant 2 FRMP Flood Risk Management Plan 3 GHG Greenhouse gas 4 HOLSC Head Office of Land Surveying and Cartography 5 IBRD International Bank for Reconstruction and Development 6 IMGW-PIB Institute of Meteorology and Water Management – National Research Institute 7 JCWP Water body - a basic water management unit under Polish water law, in accordance with the Water Framework Directive 8 JV Joint Venture 9 KZGW National Water Management Authority 10 M.P. Monitor Polski (Official Journal issued by the Prime Minister for official announcement of internally binding legal acts issued by supreme state authorities) 11 NGO Non-government organization 12 DMT Digital Terrain Model 13 NN Normal-Null - sea level set for Amsterdam 14 OVFMP Odra and Vistula Flood Management Project 15 PRDBA Polish Red Data Book of Animals 16 PCU Project Coordination Unit 17 PP Procurement Plan 18 Project Odra and Vistula Flood Management Project 19 SWHPW ZZ Szczecin, the State Water Holding Polish Water, Catchment Management Board in Szczecin Ordering Party, the Client 20 Task / Contract Chlewice-Porzecze. Backwater embankment of the Odra River at the Myśli River and 1A.1 Modernization of the Marwicki polder stage I and II 21 Flood protection of Ognica village on Odra River. Osinów-Łubnica. Modernization of Task / Contract inter-embankment. Flood protection of Radziszewo and Daleszewo villages on Odra 1A.2 River at 726+400÷727+960 km. Modernization of Marwicki polder - stage I and II. Modernization of pump station. 22 Task / Contract Restoring natural values of Lower Odra Valley by improving retention and flood 1A.3 protection capacities of Międzyodrze 23 Design and Construction Supervision for works. Project management, technical Task / Contract 5.3 assistance and support for project implementation units in the scope of implementation of the Odra and Vistula River Basin Flood Protection Project 24 WB The World Bank
Dictionary of terms
NO. TERM NAME
1 Alluvial soils Soils resulting from river, lake or sea alluvium
2 Backwater A rise in the water table flowing that progresses upstream of a watercourse as a result of rising water levels in the final tank into which the water flows - e.g. in the sea, lake or river receiving the inflow; The branch of the river or its former channel still containing water and forming a shallow lake
3 Bathymetry Department of hydrology dealing with depth measurements of water courses and water bodies
Page 2 of 36 NO. TERM NAME
4 Biocenose Interdependent group of living organisms living in a given natural habitat
5 Biotype The inanimate part of the ecosystem that constitutes the living space of living organisms
6 Chiroptera All the bats living in the given area, habitat
7 Decession Increased process of humification and mineralization of organic components of hydrogenic soils, constituting the process of moorshification and occurring in conditions of reduced or interrupted hydration
8 Dredging Mechanical removal of bottom sediment from water bodies or water courses
9 Ecological Directed, extended in the time, process of replacing one plant community by another in a succession given place, related to the mutual interaction of species (biological competition) and their modifying impact on the abiotic environment (abiotic factors)
10 Ecotone An ecosystem that is a transition zone between at least two ecosystems
11 Entomofauna Insects occurring in a given geographical area or habitat
12 Eutrophic waters Freshwater, characterized by a high concentration of water-soluble nutrients, which results in a strong development of biological life with a simultaneous decrease in the amount of oxygen in the water and a reduction in mineralisation processes.
13 Flood wave Transient hydrological phenomenon arising in natural water courses, water reservoirs, channels or at sea as a result of sudden runoff of large rainwater or melt water masses, the water mass creates a high level of the water level in the shape of an embankment moving along the watercourse, creating a potential flood risk
14 Fluviogenic peat A type of low moor in which water stagnating in the ground originates from periodic bog flooding of river waters, and to some extent also from surface runoff
15 Herpetofauna All of the amphibians and reptiles occurring in the given area
16 Humification Processes of transformation of soil organic matter based on partial decomposition of primary organic compounds (e.g. plant remains) and secondary synthesis.
17 Hydrograph Graph showing variation in flow time (m³/s)
18 Ichthyofauna All fish species occurring at a given geological time in a given water body
19 Macrobenthos They are benthic animals (living at the bottom of water bodies) bigger than 1 mm (retained on a sieve with a mesh size of 1 mm). In general, macrobenthos include freshwater oligochaete, crustaceans, aquatic insects, and freshwater molluscs.
20 Malacofauna Molluscs - a type of animal, the second most numerous after arthropoda, covering about 130,000 living species
21 Mesoregion A unit of physical-geographical division of space, covering a larger area with similar environmental and landscape features
22 Mire Type of wetlands, the final stage of overgrowing of the lake, with a occurring plant blanket on the surface of the overgrown lake, under which there are residual water or semi-liquid lake sediments
23 Molinietum A type of variable moisture content meadow largely built by Molinia caerulea. caeruleae 24 Odrzysko Old bed of the Odra River
25 Ornithofauna All birds living in the area, environment or living in a specific epoch
26 Oxbow lake A lake lying at the bottom of a river valley, being a fragment of its former riverbed and cut off from the present current by an embankment.
27 Peat bog The area is characterised by high humidity, peat deposits and marsh vegetation, which gives rise to peat.
28 Phytobenthos A set of organisms traditionally classified as plants associated with the bottom of a water body or a watercourse and the bottom zone
Page 3 of 36 NO. TERM NAME
29 Polder Usually a natural floodplain
30 Restoration The process of restoring the environment to its natural state, which is as close as possible to its original state before human modification, e.g. restoring the natural river bed to its natural, meandering riverbed.
31 Retention capacity The amount of rainwater and snow water that a given area / reservoir can take
32 Riparian forest Forest community, occurring on rivers and streams, within the range of flood waters, which carry and settle fertile silt during the flood.
33 Sand grasslands Low, loose, pioneer communities, dominated by clump, xerophylic grasses, sometimes with a higher proportion of low flowering perennials, most often not economically used or extensively grazed.
34 Sapropel Bottom sludge of ageing or contaminated water bodies, dark from iron sulphides, rich in organic matter decomposed by micro-organisms
35 Silt material Bottom-surface excavated material arising from the dredging of surface water or hydraulic constructions
36 Taxon Systematic unit of living organisms, e.g. species, genus, family
37 Terrestrialization The process of transforming the aquatic environment into terrestrial equipment
38 Water trophy Intensity of organic substance synthesis processes by photoautotrophic organisms, i.e. cyanobacteria, algae, higher plants
39 Weir Hydraulic construction built across the river or channel, damming water, in order to include maintaining a constant level of the river for navigation or flood protection
40 Willow orchard Willow thicket
Page 4 of 36 Table of Contents Summary in a non-specialist language...... 6 1. General information about Task 1A.3 ...... 9 2. Objective and scope of Task 1A.3 ...... 10 3. Characteristics of the area...... 11 4. Results of the conducted activities...... 17 4.1. Annual wildlife inventory...... 17 4.2. Geodetic inventory of water facilities ...... 22 4.3. Hydraulic modelling ...... 23 4.4. Testing of physico-chemical properties of waters and bottom sediments ...... 29 4.5. Climate change and adaptation processes...... 30 5. Conclusions - hydrological and natural model...... 31 6. Social consultations ...... 33 7. Financial summary ...... 35 8. Summary ...... 35 9. Appendices...... 36
List of Tables
Table 1 Characteristics of Międzyodrze polders...... 13 Table 2 Międzyodrze hydrography...... 14 Table 3 Hydraulic constructions...... 23 Table 4 Summary of data used in the model...... 25
List of Figures Figure No. 1 Map showing the division of Międzyodrze area into polders...... 13 Figure No. 2 The map showing Międzyodrze area at the background of spatial forms of nature protection...... 15 Figure No. 3 Międzyodrze map - the area covered by modelling together with the specified water facilities...... 24 Figure No. 4 The floodplain area and volume for the Międzyodrze area for floods with a flow probability of Q10%...... 28 Figure No. 5 The floodplain area and volume for the Międzyodrze area for floods with a flow probability of Q1% ...... 28
Page 5 of 36 Summary in a non-specialist language
This Final Report was created to summarise conceptual works related to the preparation for the implementation of Task 1A.3. "Restoring natural values of Lower Odra Valley by improving retention and flood protection capacities of Międzyodrze" carried out under the Contract for consulting services No. 5.3 " Design and Construction Supervision for works, Project Management, Technical Assistance and Training Technical Support for the Project and Strengthening of PIU’s Institutional Capacity " signed on 17 March 2017 by Sweco Consulting Sp. z o. o. from Poznań (the leader of the consortium of companies) and the Ordering Party, then the West Pomeranian Board of Land Amelioration and Water Facilities in Szczecin, currently the Catchment Management Board in Szczecin.
Task 1A.3 is part of the Odra and Vistula River Basin Flood Protection Project, which is implemented in cooperation with international financial institutions, including the International Bank for Reconstruction and Development (World Bank) and the Council of Europe Development Bank (Loan No. IBRD 8524). The project is included in the Flood Risk Management Plan (FRMP) on the List of strategic technical investments planned for implementation in 2016-2021, with the recommendation to verify its legitimacy with respect to the implementation of the flood protection objective and its impact on the natural environment. The aim of the project was to increase flood safety by increasing the retention capacity of Międzyodrze, while ensuring care for natural values. The need for verification resulted from the insufficient level of knowledge about the potential effects and expected effects, including environmental effects, at the stage of preparation of the Flood Risk Management Plan.
Międzyodrze is an area of approximately 5,456 ha, located between two branches of the Odra River, intersected by a dense network of channels and drainage ditches, used in the past for agricultural purposes (mainly as meadows and pastures), and currently excluded from commercial use. In order to ensure the possibility to regulate the flow of water for agricultural purposes, the area was surrounded by embankments equipped with water facilities (locks, weirs, pumping stations). After the abandonment of agricultural maintenance, both the embankments and the facilities were devastated and today they do not perform the original function of regulating the flow of water. The flow of water in the canal network has been significantly reduced. The above contributed to the development of characteristic natural resources, dependent on the created water regime. Due to the abandonment of agricultural management, the system is constantly changing, in particular overgrowing and glaciation. The natural conditions of the area and the way of controlling the Widuchowa Weir, which "drives" most of water to the Eastern Odra, force the flow of water from east to west in order to equalise the water levels between the Eastern and Western Odra. The currently overgrown part of the channels blocks the natural flow of water. Międzyodrze's water facilities are listed in the Voivodeship Monument Register, which is supervised by the Voivodeship Monument Conservator. They also constitute an area of historic cultural value included in the voivodeship spatial development plan.
Task 1A.3 material plan included repair and restoration of functionality of water facilities (inlet and outlet), modernisation of embankments and cleaning of some of the channels. The expected effect was to increase the importance of the area in flood protection by optimising the use of retention capacity.
Page 6 of 36 The scope of preparatory work included (in accordance with the FRMP) the development of a hydrological and natural model that would analyse the scope of the project to be carried out and assess the potential effect in terms of flood safety and the impact (positive and negative) on the natural environment (with particular emphasis on natural values). In view of the problem identified and the scope of the work, it has been developed:
- comprehensive wildlife inventory, whose aim was to identify natural resources, diagnosis of the state of protection, taking into account legal requirements, determination of the potential impact of activities planned under the contract on the environment; - geodetic inventory of facilities, the purpose of which was to determine the possibility of using the existing technical infrastructure, taking into account its functions, technical condition and location; - a hydraulic model, by means of which simulations of possible effects and their significance for increasing flood safety were carried out; - water quality analysis and bottom sediment analysis in order to be able to assess the impact of planned works; - analysis of vulnerability to climate changes and adaptation capacity of the Międzyodrze. On the basis of the hydrological and natural model developed, it was stated that the implementation of the planned measures would not contribute to a significant increase in flood safety. The existing retention capacity (140 million m3, approx. 5% of the flood wave volume with a probability of occurring every 100 years) and the possibility of its increase are insufficient to limit the effects of floods. The scenario involving the use of existing water facilities to optimise access to existing potential was analysed. It is assumed that by means of water facilities, during the flood wave passage, the area will be used to prevent flooding of protected areas in the flood wave climax phase. The simulations carried out show that this way, it is possible to slightly influence the level of flood waters in the initial phase of the wave transition. Międzyodrze, as a natural floodplain polder, is filled with water inflow up to the level of the existing embankments. At the time of flood wave accumulation, the area is completely underwater and no additional quantities can be absorbed.
Limitations on the use of Międzyodrze in increasing the level of flood safety: - limited area - the area is limited by two branches of the river, it is not possible to enlarge it; - no possibility to raise the embankments - the existing embankments are not of flood protection character, and due to natural limitations (including overgrowing riparian habitats) it is not possible to raise them and achieve the required parameters; - it is possible to increase the canal retention by deepening and cleaning the channels is insufficient (approx. 0.7 million m3 with 50% deepening of existing channels by 50cm) to achieve a satisfactory effect; - a complex hydrological system, consisting of a network of canals, water facilities, the shape and management of the area, which limits the effective control of the available capacity; Although it is not possible to achieve the assumed objective of the task and as a consequence, the resignation of its implementation, the necessity to restore the flow in the Międzyodrze canals and water exchange between the area and the surrounding river branches was determined as a desirable measure, both to maintain the retention capacity and to restore the natural values formed during the agricultural use of the area.
Page 7 of 36 In order to achieve the above mentioned objectives, the possibility of carrying out activities consisting in cleaning the inlet devices and deepening the selected, limiting the flow of channels was analysed. It was found that such measures would enable the flow but they would not restore the flow. The flow of water is determined by functioning of Widuchowa Weir, which can be used to create differences in water levels between the surrounding arms of the river. However, this effect is insufficient, and an additional limitation is the division of the area into three hydrologically isolated polders.
The results of the analyses and the conclusions of the preparatory work are made available for use in the management of the Międzyodrze area. Due to the synthetic nature of this study, detailed references to sources of data and information acquisition, as well as the literature items used, are included in the attached studies, which are the basis for preparing the Final Report.
Page 8 of 36 1. General information about Task 1A.3
Task 1A.3. The "Restoration of the natural values of the Lower Odra Valley by the improvement of the retention and flood protection capacities of Międzyodrze" is an element of the Project of Flood Protection of the Odra-Vistula River Basin (OVFMP), which is implemented in cooperation with international financial institutions, including the International Bank for Reconstruction and Development (World Bank) and the Council of Europe Development Bank (under the Loan Agreement concluded on 10 September 2015 between the Republic of Poland and the International Bank for Reconstruction and Development, loan no. IBRD 8524-PL and the Loan Agreement concluded in 2016 between the Republic of Poland and the Council of Europe Development Bank). The scope of the entire Project includes flood management infrastructure and related technical measures in three separated areas of Poland: the Middle and Lower Odra basin; the Kłodzko Valley (the Nysa Kłodzka basin); and the Upper Vistula basin.
The project was divided into five components: 1) Component 1. Flood Protection of the Lower and Middle Odra; 2) Component 2. Flood Protection of the Kłodzko Valley; 3) Component 3. Flood Protection of the Upper Vistula; 4) Component 4. Modernization and expansion of the monitoring and warning system; 5) Component 5. Project Management. Under Component 1, among others, Subcomponent 1.A Flood protection of areas in the West Pomeranian Voivodeship, for the implementation of which is the responsibility of the State Water Holding Polish Water Catchment Management Board in Szczecin. In addition to the Task 1A.3 mentioned above, it also includes:
§ Task 1A.1. Chlewice-Porzecze. Backwater embankment of the Odra River at the Myśli River and Modernization of the Marwicki polder stage I and II, § Task 1A.2. Flood protection of Ognica village on Odra River. Osinów-Łubnica. Modernization of inter-embankment. Flood protection of Radziszewo and Daleszewo villages on Odra River at 726+400-727+960 km. Modernization of Marwicki polder stage III - pump station. Preparatory works in connection with the implementation of Task 1A.3 under the OPDOW Project are covered by the Consulting Services Contract No. 5.3 "Design and construction supervision. Project management, technical assistance and support for project implementation units in the scope of implementation of the Odra and Vistula River Basin Flood Protection Project". The agreement for consulting services was signed on 17 March 2017 by the leader of the consortium of companies, i.e. Sweco Consulting Sp. z o. o. from Poznań and the Ordering Party, the West Pomeranian Board of Land Amelioration and Water Facilities in Szczecin(currently SWHPW ZZ Szczecin).
This report is a summary of the preparatory works carried out together with conclusions concerning the functioning of the Międzyodrze area in the context of flood protection and the possibility of increasing retention while improving environmental conditions.
Page 9 of 36 2. Objective and scope of Task 1A.3
Task 1A.3 was placed on the List of strategic technical investments planned for implementation in 2016-2021, which is included in the Flood Risk Management Plan (FRMP), which is an appendix to the Regulation of the Council of Ministers of 18 October 2016. on the adoption of a Flood Risk Management Plan for the Odra river basin district. FRMP is a strategic document that includes in a systemic way investments that are significant as part of creating a flood protection for the country.
The basis for including the above mentioned task in FRMP were to assume that due to conditions, including primarily location, hydrological and hydrotechnical conditions, by using technical means, the significance of the Międzyodrze area in reducing flood effects can be increased, which is consistent with the objectives of OVFMP.
One of the expected effects of Task 1A.3 was the achievement of hydrological equilibrium in the entire Międzyodrze area between the two branches of the Odra River: the Western Odra and the Eastern Odra, by providing channels, ditches and water facilities to ensure proper fertilizing and quick drainage of naturally valuable areas at the same time raising the level of flood protection of the areas adjacent to the Odra River.
The scope of activities adopted for implementation included restoring the functioning of the hydrotechnical infrastructure originally created for the purpose of using the area for agricultural purposes, through renovation and improvement of the control system of 32 water facilities, cleaning and deepening of selected channels and sealing the embankment separating the area from the riverbed of the Odra River. It was also assumed that a communication infrastructure would be built to serve the technical service of the building and to enable orderly uncontrolled tourist traffic in the Międzyodrze area, which would disturb the natural balance and have a negative impact on the technical condition of hydrotechnical equipment. It was assumed that the planned activities may contribute to improving the nature of the Międzyodrze area, in particular by restoring the flow of water in its channels and ensuring its proper level. However, due to the lack of sufficient data to assess both the achievable flood effects and the environmental impact, it was assumed that preparatory (conceptual) works should be carried out prior to the commencement of the works. The main element of this work was the development of a hydrological and natural model, which collected the results of all the analyses and whose aim was to determine the legitimacy of the task in terms of increasing flood safety, taking into account the requirements in terms of environmental impact, with particular emphasis on natural values.
As part of conceptual works, the necessary data was obtained and developed, analyses were carried out, and the results and conclusions were included in the prepared studies. After obtaining the data, research began with determining the relationship between the characteristics of the area (location, hydrological relations, existing hydrotechnical equipment) and the potential to reduce the effects of floods, identified as the possibilities of using and increasing the existing retention capacity of the area.
Page 10 of 36 Considering the above, the following works and analyses were carried out: § analysis of available information on the subject of the study, including in historical terms, in particular to identify the characteristics of the area, the genesis of its shape and function (Chapter 3 and Appendix No. 6); § analysis of available data describing the area in terms of geodetic, hydrological, morphological (Chapter 3 and Appendix No. 6); § development of a hydrological model of the area, describing hydrological relations together with identification of relations with the environment, including using existing water facilities (Chapter 4.3 and Appendix No. 3); § geodetic inventory of existing water facilities, in terms of technical condition and technical parameters important in the process of water flow control (Chapter 4.2 and Appendix No. 1); § natural inventory, the purpose of which was to identify natural resources, analyse the potential impacts of planned works and identify links between planned activities and improving conditions for selected species of plants and animals (Chapter 4.1 and Appendix No. 2); § simulations and analysis of variant technical solutions in the scope of impact on the functioning of Międzyodrze (Chapter 4.3 and Appendix No. 3); § bottom sediment tests to identify potential effects of dredging works (Chapter 4.4, Appendix No. 4); § physico-chemical analysis of water to determine the potential effects of project activities (Chapter 4.4, Appendix No. 4); § analysis of the effects of planned works in the context of climate protection and adaptive changes (Chapter 4.5, Appendix No. 5);
The listed activities and their effects were widely consulted as part of an information and consultation campaign, in particular with representatives of local communities and ecological organisations.
3. Characteristics of the area
Międzyodrze is located in the West Pomeranian Voivodeship, in four communes: Gryfino, Szczecin, Widuchowa, and Kołbaskowo. It is part of the mesoregion of the Lower Odra Valley. The length of Międzyodrze is 33 km and its area is about 5456.5 ha. The landscape of this area was shaped at the stages of the recession of the youngest glaciation in the Pomeranian phase. Międzyodrze area has a small elevation above 0.1-0.5 m above sea level.
The extensive peat bog Międzyodrze has been adapted for meadow and pasture use through melioration. These polders, until the end of the 1960s, were used for agricultural purposes in spring and summer. However, for autumn and winter seasons, they were prepared for inundation.
The most important impact on the formation of the Międzyodrze area had regulatory work carried out over the years, the purpose of which was to create the possibility of economic use of the Odra River and adjacent areas. The area stretching between the branching arms of the Odra River has become attractive in terms of agricultural use, in particular as grasslands, meadows and pastures. In order to increase the efficiency of the area use, the hydrotechnical infrastructure was built, which enabled to control the water level depending on the needs related to the maintenance of optimal water conditions. Constructions and water facilities located in Międzyodrze are subject
Page 11 of 36 to conservation protection. They were entered into the voivodeship register of monuments (pursuant to the Act of 23 July 2003 on the protection of monuments and care of monuments (Journal of Laws of 2018, item 2067). The spatial development plan for the West-Pomeranian Voivodeship indicates the areas with historic cultural values (Resolution No. XLV/530/10 of the West-Pomeranian Voivodeship of 19 October 2010 on the adoption of a change in the spatial development plan for the West-Pomeranian Voivodeship).
One of the technical elements enabling agricultural use was the embankment, which was erected to a height corresponding to the flow of the Odra river equal to 1600 m3/s (according to the Hohensaaten gauge), with Dąbie lake rising to a height of + 0.7 m NN. As a part of it, a tunnel was made below Widuchowa in the direction of Western Odra, it was covered with embankments on both sides and a gate weir was built, which allowed for engineering of water distribution for Eastern Odra and Western Odra. For the purpose of conceptual works, based on the numerical model of the area, the technical condition of the embankment was assessed. Due to the abandonment of maintenance work, which is a consequence of changing the way the area is used, the embankment is in poor technical condition, it is lowered or damaged in many places, as a result of which water reaches the polders at flows lower than 1600 m3/s.
Another characteristic element of Międzyodrze is the rich network of channels, which form the specific water system of the area. In the northern part of Międzyodrze, the Eastern and Western Odra have a connection via the Klucz-Ustowo shipping channel. From this channel, the Eastern Odra changes its name to Regalica and flows into Dąbie lake. The second channel connecting both arms of the Odra is the Odyniec Channel, running parallel to the Klucz-Ustowo channel, from which the Western Odra changes its name to the Odra of Szczecin.
According to the Water Management Plan in the Odra River basin (Regulation of the Council of Ministers of 18 October 2016 item. 1967) Międzyodrze waters are classified as surface water - a great lowland river with code 21. Międzyodrze area lies within the area of the Odra River surface water body (JCWP) from the Western Odra to the Parnica River PLRW6000211971 and JCWP Odra from the Parnica River to the estuary PLRW6000211999, which have a strongly modified status, therefore the ecological potential of the water bodies is subject to assessment.
There are numerous oxbow lakes and odrzyska in the area of Międzyodrze. They remain in various relationships with riverbeds. Oxbow lakes have contact with the mainstream, water level fluctuations are large and often strongly generated by water levels in the riverbed. Odrzyska as forms isolated from the direct impact of riverbed waters are fed with groundwater, flood and rainwater. In fluvioglacial depressions, water is found on the surface throughout the year. Water movements along Międzyodrze are limited by three transverse embankments: fills of the Gryfino-Mescherin road and Klucz-Kołbaskowo motorway as well as railway fills in Zaleskie Łąki. As a result, it is possible to divide them into three separate polders (according to Table 1 and Figure No. 1), which differ from each other in terms of hydrographic conditions and the natural values associated with them.
Page 12 of 36 Table 1 Characteristics of Międzyodrze polders Total surface of channels Area Average height and ditches Name of the polder [meters above sea [ha] [ha] level] Southern (Widuchowski) 2 465,5 0,1 348,5 Central (Gryfiński) (on the 2 232,4 0,2-0,3 135,0 map northern part I) Northern (Szczecin) (on the map northern part II 758,6 0,2-0,3 137,3 and III) Total: 5456,5 620,08 Source: materials developed for the needs of conceptual works
Figure No.1 Map showing the division of Międzyodrze area into polders
Source: materials developed for the needs of conceptual works
Page 13 of 36 Table 2 presents the main channels with their hydrological characteristics:
Table 2 Międzyodrze hydrography
Main river Stream order I Stream order II Stream order III Western Odra Skośnica Przecznica Obnica Kanał Kurowski Kanał Żeglica Żeglicki Przekop Kanał Wtórny Kanał Błotny Kanał Drzewny Kanał Moczydłowski Kanał Czarny Kanał Gryfiński Kanał Szeroki Kanał Długi Kanał Leniwy Kanał Wąski Kanał Krzyżowy Stary Kanał Kanał Węzłowy Western Odra Kanał Leśny (Odyniec) Obnica Kanał Klucki Tributary from Wełtyń lake(Omulna) Kanał Dolna Odra+ Tywa Stara Reglica Krzywa Reglica Mała Reglica Kanał Marwicki Kanał Mały Tributary from Kiełbicze lake Tributary from Widuchowskie lake Source: materials developed for the needs of conceptual works
At present, there is no water management at Międzyodrze. Inundation of the area happens in an uncontrolled manner, depending solely on the conditions on Odra River. Międzyodrze also does not fulfil the function of a flow regulator in Eastern and Western Odra. However, it still has an impact on shaping flows, because a constant and free exchange of water takes place through Miedzyodrze between Eastern and Western Odra.
The largest area of Międzyodrze - 81% of the area is covered by wood free marsh vegetation. The swamp forests cover only 4% of the area. Open water areas - oxbow lakes, sandbars, canals occupy a total of 11.6% of the area (an extensive network of channels measuring over 200 km in length). Small percentage shares in the area are also attributed to extensively used meadows and pastures -1.2% and embankments, dirt roads and sandy areas -2.2%. The rivers East Odra and West Odra mark the border of Międzyodrze.
Międzyodrze has a retention function due to the existence of a specific capacity of this area. At the moment of rising flood wave, Międzyodrze gradually fills up with water. Then, after the culmination of the wave, the excess of water is discharged back to the river. In the case of river high water - when goes down the river, Międzyodrze lowers the water level in the sections of Eastern Odra and Odra, mainly in conditions of the average state of Szczecin Lagoon. One of the elements significantly affecting the nature of Międzyodrze and the scope of activities being analysed are its natural assets. Międzyodrze is a unique ecosystem, largely dependent on hydrographic conditions. Międzyodrze area, as part of the Lower Odra Valley is a place of
Page 14 of 36 occurrence of many valuable plant and animal species. Details are presented in Appendix No. 2 on the nature inventory carried out as part of the preparatory work. The area is within the range of spatial forms of nature protection, as illustrated in Figure No. 2.
Figure No. 2 The map showing Międzyodrze area at the background of spatial forms of nature protection
Source: materials developed for the needs of conceptual works
Page 15 of 36 The Lower Odra Valley Landscape Park covering the entire Międzyodrze area was created in 1993 by Regulation No. 4/1993 of the Governor of Szczecin (Journal of Laws of the Governor of Szczecin No. 4, item 50). The special purpose of protecting the Park is to preserve and promote its natural, historical and cultural values as well as landscape values in conditions of sustainable development through:
1) the maintenance and restoration of a landscape which is close to natural and harmonious cultural landscapes, with particular protection for the following elements: a. natural: natural biocenoses of natural and semi-natural character, populations of plants and animals of protected and endangered species, rare and crucial for the functioning of ecosystems; roadside and near-water woodlots and other elements of the natural environment conditioning the preservation of the Park's biodiversity, b. cultural: archaeological sites, historic and other valuable architectural objects; 2) preservation and introduction of universal accessibility of natural and landscape values, without development of infrastructure connected with servicing tourist traffic; 3) running a business in a way that minimises environmental and landscape impacts; 4) development of infrastructure improving the condition of the natural environment.
In the northern part of the Landscape Park is the Kurowskie Błota nature reserve, created under the the Ministry of Forestry and the Wood Industry Order of 20 October 1965. regarding recognition as a nature reserve (M.P. of 1965, No. 64, item 356). The main purpose of the reserve's protection is to preserve the breeding sites of birds, especially the gray heron Ardea cinerea, and to preserve the alder in an unchanged state that is distinguished by its high biocenotic values and natural forest succession processes.
Międzyodrze area is within two areas of the ecological network Natura 2000. Under the Council of Europe Habitats Directive (92/43/EEC of 21 May 1992) on the protection of natural habitats and wild flora and fauna, is within the boundaries of the Special Protection Area of the Lower Odra PLH. Międzyodrze, as a peat island located between the Eastern Odra and Western Odra, it is the area of the largest fluviogenic (flooded) peat bog in Europe up to 10 m thick, cut through with a network of channels, oxbow lakes, ditches and floodplains with a total length of approx. 200 km. In these special conditions, with very limited management, a characteristic flora developed in this place. Well-preserved habitats provide shelter and resting places and food for many rare and endangered species of animals.
The objects of protection in this area include:
§ eutrophic waters (CODE 3151) - oxbow lakes, swamps and canals with colourful vegetation of water lilies, § slews (CODE 7140) with low-sedge vegetation of O., Caricetalia fuscae, § thickets and riparian forests (CODE 91E0) willow, poplar, alder and ash with their natural flora and fauna, § Molinia meadows of variable moisture content (CODE 6410), § sandy xeric grasslands (CODE 2330) on silt material.
The species occurring in Międzyodrze, covered by the Habitats Directive, include: otter Lutra Lutra, beaver Castor fiber, large copper Lycaena dispar, fire-bellied toad Bombina bombina and northern crested newt Triturus cristatus.
Page 16 of 36 Pursuant to the Birds Directive (Council Directive 79/409/EEC of 2 April 1979), on the conservation of wild birds, Międzyodrze is within the area called Special Protection Area of the Lower Odra Valley PLB 320003. It is a bird refuge of E06 European rank, in which there are at least 43 species of birds from Appendix No. 1 of the Birds Directive, 14 species from the Polish Red Data Book of Animals (PRDBA). A very important area especially for water and marsh birds during breeding, migration and winter time. During the breeding season the area is inhabited by at least 1% of the national population of the following bird species: bittern (PRDBA), montagu's harrier and greylag goose; at a relatively high density there are: black tern, red-backed shrike and aquatic warbler (PRDBA). During the migration period at least 1% of the population of the migration route of the following bird species occurs: bean goose and white-fronted goose; the following species have a relatively high density: whooper swan, great crested grebe, gadwall, lapwing and European gold plover; in the autumn, there are up to 5 000 of common cranes at the staging area. Great crested grebe occurs with a high density in winter.
4. Results of the conducted activities
4.1. Annual wildlife inventory
Field investigations were carried out to verify the extent of the environmentally and socially acceptable intervention works by means of hydrotechnical works and to assess their impact. The research methodology was selected in such a way as to enable a full diagnosis of the condition of the natural environment, identification of possible environmental impacts of the planned works and the possibility of simultaneous improvement in the scope of natural conditions. The scope and manner of conducting research has been subject to extensive public consultations, including as part of organised information conferences. Międzyodrze is an extremely interesting and valuable area in terms of nature, but despite the great interest of naturalists, it has not been included in such detailed inventory studies in recent years. It was assumed that a proper assessment of the effects of planned activities should be based on treating Międzyodrze as a separate ecosystem, unlike other random inventories devoted to selected issues (species, groups, habitats), taking into account the valuable values of the area. More than twenty high-class experts were involved in conducting the wildlife inventory. One of the tasks of nature experts was to determine the sensitivity of particular species and habitats to the execution of works and their effects. As a result of the conducted research and comparisons with historical results, it was found that there are changes in the occurrence of habitats and species in the area, mainly caused by changes in water relations, including restrictions on water flow through the network of Międzyodrze channels. There were also differences found in the intensity of the above mentioned processes between individual polders. In the "southern" polder, where due to the Widuchowa weir, the flows are limited to the smallest extent, the mentioned changes are less intensive. Moving in the northern direction to the polders, also due to the barrier effect of the located roads, high overgrowing and terrestrialization intensity can be observed. The inventory was started in March 2017 and covered the full vegetation period. The report, including the methodology, results of observations and conclusions, is attached as Appendix No. 2 to this study. Below, the most important elements of the natural system of the area, from the point of view of the impact of the planned activities, are presented.
Page 17 of 36 Flora and natural habitats
In the area of Międzyodrze research, eight protected species have been documented, including three strictly protected species. None of these species is a protected area of the Natura 2000 site, although they are typical species for protected natural habitats. Due to the high category of threat in the scale of the country and exceptional rarity of occurrence in the northern part of the country, the populations of the fringed water lilly and the water caltrop are very important values of the area. Both species were discovered in the Lower Odra Valley after decades of absence. Another species under strict protection - floating saltwater - is locally very widespread and occurs in large numbers (not only in Międzyodrze, but also in the area of the Lower Odra Valley after its mouth to Szczecin Lagoon). Other species belong to those which are widespread and have large regional resources, except for watercress and marsh pea. The sand blocks recorded only once in Międzyodrze (locally rare due to unfavourable habitat conditions) are a very common species in the surrounding areas and on a regional scale.
Three natural habitats have been documented in the Międzyodrze area:
1) oxbow lakes and natural eutrophic water reservoirs with communities from Nympheion, Potamion [3150] - at least 22 patches covering 40.97 ha, 2) mountain herbs (Adenostylion alliariae) and riparian herbaceous plants (Convolvuletalia sepium) [6430] - 28 patches covering 3.27 ha, 3) willow, poplar, alder and ash riparian forests (Salicetum albo-fragilis, Populetum albae, Alnenion glutinoso-incanae, common alder forests) * [91E0] - 60 patches covering 165.05 ha.
Diatomaceous phytobenthos
Due to the possible impact of the planned works on water bodies, special attention has been paid in the research of those elements which allow for the assessment of the quality status and by determining the initial state, direction and intensity of the changes caused. One of the indicator elements containing the assessment of the ecological condition of the river on the individual channels of the Międzyodrze area is diatomaceous phytobenthos. Multiparametric diatomaceous index based on three indicators was used in the research: TI trophy index, SI saprobic index and GR abundance index of reference species and specified in 5 classes. The analyses made allowed for an objective and standardised assessment of the ecological status of the river during the sampling campaign, i.e. before the start of investment works. This was to enable an objective assessment of changes in the river ecosystem as a result of the works, as well as after their completion, and is a specific reference point necessary for the proper assessment of the environmental impact of the investment. At the same time, the analyses carried out allowed for the inventory (review) of taxa of diatoms occurring in the examined section of the river, which was to enable the assessment of changes in this ecosystem component as a result of the works carried out, during and after their completion. The ecological status of the Odra River in the Międzyodrze area was assessed using a diatomaceous index and ranging from moderate to very good. Sampling of diatomaceous phytobenthos in Międzyodrze area was performed in September 2017. During sampling, the basic physical and chemical parameters of water were measured directly in the field: electrical conductivity, pH, water temperature and oxygen content.
Page 18 of 36 During the diatom analysis, a total of 120 species of diatoms belonging to 32 species were identified for the purpose of determining the ecological status of particular research sections using the diatomaceous index.
After analysis, it was found that the diatomaceous flora occurring in the studied area does not differ from the previously recorded communities in this type of habitats (large lowland river). Intermittent rare species have been reported.
Macrobenthos and malacofauna
An important indicator element determining the quality of waters and their sensitivity to the effects of planned works (including limited water flow in the area) is macrobenthos and malacofauna. In addition, many species found in these groups are protected, including as part of the ecological Natura 2000 network. Particularly important in the river ecosystem due to the fact that they are filtrators and in the case of their mass occurrence significantly contribute to the process of self-cleaning of the river, are mussels from the Unionidae family (during their research no such occurrences were found). In addition, they are essential for the reproduction of the protected amur bitterling that spawn eggs in them. It is likely that these bivalve molluscs occur on the Międzyodrze only at very low densities, much lower than on the Odra River. Fishing with a dredge or bottom catcher does not provide exploration of sufficiently large bottom surfaces to find live individuals. The presence of a small population of Unionidae clams in Międzyodrze confirms the presence of a small amount of rosehip in this area and the presence of shells of these clams in the feeding places of otters. The reason for such a low density of mussels in the Unionidae family is probably the impaired water circulation in the channels, causing stagnation of water, accumulation of large amounts of organic matter in bottom sediments, which leads to oxygen deficits. The Uniondae living in bottom sediments do not have good habitat conditions here, as was the case in the inter-road fields on the border Odra, where the water exchange was intensive.
Despite the visually good habitat conditions, the assessment of water quality based on the ecological status assessment method based on MMI PL macrozoobenthos classified the waters of Międzyodrze as class III and IV. Such a low assessment is related to the changes taking place, which are caused by the restriction of water flow in this area. Reduced water flow causes the channels to fill with sediments, low oxygen content in the water, overgrowing with marsh vegetation, which at the extreme stage leads to terrestrialization. The overgrowth and terrestrialization process mainly affects small (narrow) channels, thereby reducing the diversity of the habitats of the entire area. Larger channels are less degradable, but even in large flow channels the process of degradation progresses, even though the symptoms are not yet visible. On the predominant surface of the bottom of these channels, deoxygenated organic deposits of sapropel character are found. Only invertebrates resistant to oxygen deficits, such as Chironomidae or Oligochaeta larvae can live in such a settlement. In such conditions, mussels from the Unionidae family, essential for the protection of the fish of the rose and self-cleaning of waters, and there are no rare and protected species there.
As a result of monitoring carried out in June and September 2017, the Anisus vorticulus (Planorbidae family) was not found at the monitoring stations tested. The reason for the regression of this species from Międzyodrze area is probably the impaired circulation of waters in canals, especially those with underwater vegetation, i.e. in places of potential occurrence of this species. With stagnation of water and a large amount of organic matter in bottom sediments, oxygen deficits occur. Anisus vorticulus is an organism with high oxygen requirements, in the
Page 19 of 36 above mentioned channels oxygen conditions are not sufficient, especially in bottom sediments, in which this species hibernates. Noteworthy is the extremely low number of other Planorbidae species found in 2017 that do not have such high oxygen requirements. Only singular individuals were found to be present.
Entomofauna and terrestrial malacofauna
Due to the natural values of the area and the potential impact of the planned works, the entomofuna and malacofauna surveys had to be carried out. Identification of the area, species composition and number of animals began in July and was completed in October 2017. Identification of the inventoried section of the Odra River in the places of the planned works together with the buffer showed the occurrence of 7 insect species, including bumblebees: large earth bumblebee, red-tailed bumblebee, common carder bee, small garden bumblebee, new garden bumblebee, shrill carder bee; and a green snaketail. No whorl snails were found during the tests.
Particularly noteworthy is the finding of the occurrence of one species from Appendix No. 2 of the Habitats Directive - the green Ophiogomphus cecilia. The occurrence of dragonfly was regularly found, along the entire length of the outer shore of Międzyodrze - on the banks of Odra. The green snaketail is a river species and in this case there is no shortage of habitats suitable for the species.
The next 6 species found belong to the Hymenoptera order. These are bumblebees of the Bombus type: large earth bumblebee, red-tailed bumblebee, common carder bee, small garden bumblebee, new garden bumblebee, shrill carder bee. All of them are subject to partial protection. The small number of observations and the small number of observed individuals clearly indicate the non-optimal habitat conditions for these insects. They require flower-rich meadows where they find food for larvae. It would be best if they were "wild" meadows, rarely mown, preferably without the participation of Taraxacum sp. Dandelions, whose occurrence indicates impoverishment of the flora. Bumblebee species found here did not find the optimum for their occurrence. These are insects under partial protection, very important from the point of view of human economy - pollinators of utility plants.
Ichthyofauna
The Międzyodrze channels are an attractive living environment for many valuable and protected species of fish. Due to the specifics of the study area, the obtained results were compared for several types of conventional habitats. Small channels were distinguished, where the absolute dominance is roach and perch - they are organisms of different sizes, sometimes in the number of several hundred organisms. In addition, single pike spawners, tench and rudd as well as some spined loaches and amur bitterlings were caught from protected species. In medium-sized channels, the prevalence of common bleaks has been observed - at least several dozen individuals at the site, perch and roach adolescents, single common rudd, asp and ide was observed, and in places with hard, sandy bottom, pumpkinseed. Within the large channels, only individual small roach were found. The last habitat type is a stagnation of various sizes where mainly roach fry, numerous young perch and common bleak as well as individual weirs, tenches, rudd, blue bream, white bream, sunbleak, common bream and northern pike - usually small in size - were observed. A spinded loach was very rare, and in one case pumkinseed was also caught. On the basis of the results obtained, it should be concluded that the number of species (biodiversity), the size of the population and the unfavourable age structure are decreasing in comparison to the reference
Page 20 of 36 values for a similar type of environment and historical data. One of the main reasons for this phenomenon was the lack of flow and oxygen limits in the Międzyodrze channels.
Among the species identified were those covered by the Habitats Directive - Appendix No. 2 - which are animal species of Community interest whose conservation requires the designation of Special Areas of Conservation (without birds). Appendix No. 2 is a continuation of Appendix No. 1 concerning the establishment of a coherent network of areas covered by special protection. The following positions were found in Appendix No. 2: asp, spined loach and amur bitterling.
In total, 20 taxa of fish were found during the wildlife inventory. Taking into account the use of only one electrofishing method on such a large area, it was possible to capture a large part of the ichthyofauna in a relatively short time, revealing not only frequent species, but also very rare ones. The number of species occurring in the waters of Międzyodrze reported by various authors is quite diverse and depends on the type of source and the time interval in which the data were collected.
Herpetofauna
Międzyodrze is a relatively homogeneous area, abundant in convenient habitats, with no migration barriers for herpetofauna, and animals can be passively transported through water. Therefore, the point on the map where individuals of a given species were found should not be treated as the only habitat - the whole Międzyodrze remains a habitat. Moreover, due to the prevailing conditions at this site, the detectability of some amphibian species (newts that do not issue mating voices) and all reptiles is much lower than the actual population status.
The most valuable species found in the area of Międzyodrze is the northern crested newt, for which smaller channels, partially overgrown with vegetation, with limited penetration by fish, are a valuable habitat. It should be remembered that the total loss of these habitats due to the removal of underwater and coastal vegetation will lead to a decline or loss of population, but also, in the current situation, the uncleaned channels will become increasingly overgrown, which will also lead to the loss of habitats in the long term.
Ornithofauna
In connection with the changes taking place in Międzyodrze, consisting mainly in the progressive succession of high vegetation and terrestrialization, changes in the range of the existing species and their abundance were found. In 2017, 100 breeding species or probably breeding birds were found in Międzyodrze, 14 of them are in Appendix No. 1 of the Birds Directive.
On a national scale, high numbers of gadwall (2.1-3.0% of the population nesting in Poland), black tern (3-5% of the national population), bluethroat (3.5% of the national population) and Savi's warbler (1.1-1.5% of the national population) should be noted. It should be noted that if no action is taken in the area of Międzyodrze and the area is allowed to gradually overgrow in the long term, the 13 species which are subject to protection of the Lower Odra Valley Natura 2000 area are likely to be adversely affected, the succession for 7 species will be indifferent, while one species is likely to benefit from the expected changes. Of the 13 species for which succession means deterioration of living conditions, the most important is the black tern, for which Międzyodrze is an important breeding ground on a national scale. In 2017, nearly 5% of the national population of the black tern nested here. Thanks to the programme started in 2017 by West Pomeranian Nature Society on creating new breeding places for the species, the number increased by 50% compared to 2016. It is to be expected that the importance of this breeding site will probably
Page 21 of 36 increase in the near future, since the implementation of a similar programme (including the creation of artificial nesting platforms) on the German side between 2003 and 2015 has more than doubled the number of the species. Taking into account the worldwide decrease of the black tern (including the North American sub-species), this is a significant argument for stopping the terrestrialization of Międzyodrze channel.
The second species to which attention should be paid is the bluethroat, for which Międzyodrze is an important breeding ground in the country. The species is not globally threatened and its world population is assessed as stable. In Poland, there is a long-term, slight downward trend, although local population increases are observed. Międzyodrze is the place where the most dramatic decrease in the number of this species has been recorded in recent years (from 100-150 to 45-55 breeding pairs). However, probably despite a significant recent decline in the number of this species, more than 2% of the national population still nests in the area of Międzyodrze. The decrease in the number of bluethroat in the analysed area is probably associated with progressive succession (the development of willow orachard and the merging of willow shrubs into compact thickets, eliminates the ecotone with which this species is associated). Stopping the landing process is also likely to stop this species from falling.
For the remaining species, Międzyodrze is not such an important breeding ground on a national scale, but its succession may have had a negative impact on the size of their national populations.
Chiroptera
Chiropterological survey of the inventoried section of the Odra River at the sites of planned works showed the occurrence of 8 species/groups of bats:
1) Nathusius's pipistrelle (Pipistrellus nathusii) 2) Common pipistrelle (Pipistrellus pipistrellus) 3) Soprano pipistrelle (Pipistrellus pygmaeus) 4) Common noctule (Nyctalus noctula) 5) Lesser noctule (Nyctalus leisleri) 6) Serotine bat (Eptesicus serotinus) 7) Pond bat (Myotis dasycneme) 8) Mouse-eared bat (Myotis sp.) Międzyodrze functions for bats as a feeding ground and a reservoir of shelters in den trees. The main feeding ground for bats are the channels where insects gather. In turn, the shelter repository consist of ripe den trees. They are concentrated mainly in the area of the Kurowskie Błota nature reserve (about 190 ha) and embankments on the western border of Międzyodrze (26 km long strip, average width 40m, around 104 ha). In the central part of the area there are mainly short vegetation and single mature hollow trees suitable for occupation by bats. On the embankments there are also old water facilities and structures that can function as bats' shelters in winter or summer. On the basis of the data obtained, it can be concluded that Międzyodrze is an important area for bats, which is consistent with the knowledge that water-related biotopes have the highest activity of bats. 4.2. Geodetic inventory of water facilities
The regulation of water flow in the Międzyodrze area was possible thanks to the operation of a number of water facilities, such as locks, weirs and pumping stations. Together with the
Page 22 of 36 Widuchowa weir, they also fulfilled the role of a flow regulator in Eastern and Western Odra. For the purposes of conceptual work, a geodetic inventory of water facilities was performed, the results of which are included in Appendix No. 1 to this Report. The main purpose of the study was to determine the technical condition of the structure, as well as the permeability of the facilities and the channels connected to them. The inventoried structures do not fulfill their functions at present, the equipment is devastated, and their parts sometimes remain in the sewers, limiting the possibility of water flow. The analysis of the register division and properties of the plots on which the hydrotechnical equipment is located was carried out. Types and number of water constructions are shown in Table 3 and their location in Figure No. 3.
Table 3 Hydraulic constructions No. Type of hydrotechnical structure Southern Middle Northern Międzyodrze and its purpose polder polder polder in total 1 Weir in Widuchowa - used for the 1 - - 1 division of water into two riverbeds, i.e. Western Odra and Eastern Odra (Regalica) 2 Chamber and navigation sluices 2 - - 2 connecting the waterway of Eastern Odra with Western Odra 3 Chamber and economic sluices, used 4 9 4 17 for transport within the washlands 4 Canals (overflows) with opening 3 2 1 6 clearance of 10 to 40 m, used to bring high water to the washland 5 Embankment culverts with self- 4 1 - 5 acting valves, used for gravitational drainage of excess water from washlands 6 Pumping stations used to lower the 2 1 1 4 water level on washlands source: „Zabytkowe budowle hydrotechniczne i inne Doliny Dolnej Odry”, study by Leszek Budych, edited by Stanisław Januszewski 4.3. Hydraulic modelling
The purpose of building the hydraulic model was, appropriate to planned analyses, mapping Międzyodrze area and conducting simulations and analyses with it to determine the necessary and possible scope of work to improve flood safety, in particular the effectiveness of the proposed measures to reduce flood risk in cities in the vicinity of Międzyodrze. The calculation scenarios concerned floods with low (0.2%), medium (1%) and high (10%) probability of occurrence.
For the purpose of developing the concept, the Międzyodrze area has been defined as a floodplain, located between two river branches, which is a natural reservoir capable of storing water, including in the case of flood embankments. Currently, the flow of water in the area is determined by the existing field conditions, shaped as a result of historical human activity, and in part as a result of spontaneous processes. The hydrotechnical infrastructure is largely devastated and does not fulfil its original function, which is related to the discontinuation of agricultural use and the introduction of passive strategies for the protection of natural resources. It was assumed that as a result of sealing and modernisation of the embankment, cleaning the canals and restoring the possibility of water flow control using the renovated infrastructure, it will be possible to increase the significance of Międzyodrze for flood safety, while at the same time improving the natural conditions. Due to the importance of the area for the protection of natural resources, the impact
Page 23 of 36 on the environment, including species and natural habitats, was adopted as one of the main criteria for the assessment of the proposed solutions. Modelling covered the area from the Widuchowa stream gauge to the stream gauges Szczecin Most Długi on Western Odra and Most Cłowy on Odra. 35.8 km of Odra have been mapped - km 701+800 - 737+600 and 36 km of Western Odra - km 0+000 - 36+000. The canals located within Międzyodrze region have been included. The total area covered by the modelling is 128.28 km2. It was decided that the model will reflect the area of Międzyodrze in the event of a rainfall/run-off flood from the south. Despite the fact that this area is within the range of the sea backflow, due to the nature of this type of flood, its violent course, short duration, lower water climaxes (compared to a rainfall flood) and its dependence on water levels rather than flows and the impossibility to control devices in such a limited time, there was no justification for introducing the backflow into the model. It should also be borne in mind that the highest observed water levels resulting from the occurrence of these phenomena were about 1.0 m above sea level and the flood protection of the towns located in the Lower Odra Valley, whose flood embankment crowns have ordinates significantly above the extreme water level, which ensures proper protection against such phenomena.
Figure No.3 Międzyodrze map - the area covered by modelling together with the specified water facilities
Source: materials developed for the needs of conceptual works
Page 24 of 36 To implement the model, data and calculations made by the Institute of Meteorology and Water Management - National Research Institute (IMGW-PIB) were used. As a result, IMGW-PIB provided the ordered data in the study entitled "Values of water levels and maximum annual flows with a specified probability of exceeding, together with hypothetical hydrographs in the water level gauge sections Szczecin Most Długi, Gozdowice, Bielinek located on the Odra River". The method of Warsaw University of Technology was used to calculate hypothetical waves in water gauge cross-sections. This method is and has been successfully used in many projects related to water management in Poland.
At least 6 flow hydrographs actually registered are used for calculations in the method of Warsaw University of Technology. Checking the correctness of using this method is possible by comparing real flow hydrographs with hypothetical ones.
The maximum flow observed in Gozdowice in 1997 was approximated to the flow with a probability of exceeding 0.2%. Therefore, a direct comparison of the real hydrograph from 1997 has been made with a hypothetical hydrograph for Qmax = 0.2%. Maximum flows registered during high water in 2010 were approximated to the flows with a probability of exceeding 10%. For comparisons, a hypothetical hydrograph with a probability of exceeding 10% (Qmax = 1830 m3/s) was scaled to a hydrograph with a maximum flow of 1620 m3/s. There was no comparable historical flooding for flows with a probability of exceeding 1%.
The analysis of hydrographs shows that the hypothetical flow hydrographs determined by the method of the Warsaw University of Technology well reflect historical floods with a high probability of occurrence (10%). For the extreme phenomenon (0.2%), especially in the falling part, the hypothetical wave deviates from the one observed in 1997. However, it should be noted that in the culmination part (flows above 2500 m3/s) the shape fit is very good.
Comparison of the volume of hydrographs showed that the hypothetical wave for Qmax = 0.2% is 39% higher than the actual wave from 1997. (cut off of hydrographs at 1000 m3/s). However, the 3 volume of the hypothetical wave for Qmax= 1620 m /s is smaller than the volume of flood from 2006 by 11% (cut off of hydrographs at 500 m3/s).
Calculations made by IMGW-PIB can be successfully used for calculations under the developed hydraulic model for Task 1A.3. The selected method is based on real hydrographs, which minimises the possibility of obtaining hydrographs that do not adequately reflect the course of hypothetical high water.
Table 4 Summary of data used in the model Name Source Revision
Spatial and inventory data
Digital terrain model (DTM) Head Office of Land 2011 Surveying and Cartography (HOLSC)
Digitalen Geländemodells des Wasser- und 2011 - aerial laser Oderwasserlaufes (DGM-W Oder-2011) – Schifffahrtsamtes scanning numerical terrain model of Odra waterway Eberswalde 2006, 2008 and 2009 - bathymetry of the Western and Eastern Odra
Page 25 of 36 Orthophotomap for Poland Head Office of Land 2011 and 2012 Surveying and Cartography
Orthophotomap for Germany Landesvermessung und 2016 Geobasisinformation Brandenburg
Topographic object database (BDOT10k) Head Office of Land 2012-2013 Surveying and Cartography
Land cover and development for Germany OpenStreetMap 2017
Inventory of hydraulic structures along the Precyzja S.C. 13-27.06.2017 banks of the Odra in km from 0.0 to 29.5, the East Odra (Regalica) in km from 704.0 to 730.0 and the Obnica in km from 0.0 to 1.1
Photographic documentation of Międzyodrze SWECO Consulting sp. z 17.05.2017 area o.o.
Data from geodetic measurements of cross- National Water 2012 sections of the Odra and the Western Odra Management Authority (KZGW)
Hydrological data
The largest rainfall and storm floods Institute of Meteorology 2017 recorded on the Lower Odra at selected and Water Management – water gauge stations (IMGW_PIB 2017a) National Research Institute (IMGW-PIB)
Water levels for the largest rainfall and storm Regional Water 2017 water for Gartz and Mescherin gauges on the Management Board in Western Odra Szczecin
Values of water levels and maximum annual Institute of Meteorology 2017 flows with a specified probability of and Water Management – exceeding, together with hypothetical National Research Institute hydrographs in the water level gauge sections Szczecin - Most Długi, Gozdowice, Bielinek (IMGW-PIB 2017b)
Other data, including hydraulic models for other studies
Report on the development of flood hazard National Water 2015 maps and flood risk maps Management Authority
1D hydraulic model for the Odra River from National Water 2015 the Bielinek water gauge to the Gryfino water Management Authority gauge for a 0.2%, 1% and 10% flood probability
2D hydraulic model for the Odra River from National Water 2015 the Gryfino water gauge to the Trzebież Management Authority water gauge for a 0.2%, 1% and 10% flood probability Source: own studies
Page 26 of 36 Modelling is based on the following assumptions: § Międzyodrze is a natural flood plain, which plays an important role in limiting the effects of floods, caused both by rainfall and the so-called "backwater", by accepting flood water; § as activities that could potentially result in increasing the water-retention capability, it was assumed: repair and modernisation of embankments, restoration of functioning of hydrotechnical devices, clearing and deepening of canals, restoration of flow in the area; § based on DEM, the following data was introduced: bathymetry of riverbeds and canals, geometry of inventoried hydrotechnical structures, water management instruction for the weir in Widuchowa, appropriate coefficients of roughness corresponding to the condition of canals (in some cases completely overgrown with blocked flow) were introduced, as well as available data on states and flows for historical high water waves were introduced. The calculations were carried out for 3 scenarios [Q10% - probability of occurrence once every 10 years, Q1% - probability of occurrence once every 100 years, Q0.2% - probability of occurrence once every 500 years].
Three modelling variants were selected:
1) Variant "0" - mapping of the current state in terms of functioning of hydrotechnical devices, embankment and canal condition, in which Międzyodrze area is a natural flood polder; 2) Variant "1" - the purpose of the analysis of this variant was to examine the effects on flood protection related to further shallowing and overgrowing of Międzyodrze canals; 3) Variant "2" - in which the effects on flood protection were analysed, which can be achieved by creating a controlled inundation washland by: sealing and aligning the embankment crown, dredging 50% of Międzyodrze canals - deepening them by 0.5 m including the exclusion of natural valuable canals from the works (value determined on the basis of the average amount of sediment stuck in the bottom of the canals), restoring the efficiency and control of hydrotechnical devices to delay the culmination of the flood wave culmination.
The analyses carried out as part of modelling indicated that the retention capacity of Międzyodrze and its possible increase does not have a significant impact on reducing the effects of potential floods. The total retention capacity of Międzyodrze is about 140 million m3, which is about 5% of the flood wave volume for floods with a probability of occurring every 100 years. It was also stated that as a result of the implementation of technical measures planned under the contract, there will be no significant increase in the flood protection significance of the area. Additional capacity possible to obtain, as a result of cleaning and deepening of selected channels and repair of embankments and water facilities accounts for a few percent of the currently available capacity. The possibility of optimising the use of the existing retention volume by restoring control of inlet devices by making it available at the right moment was also analysed. It was found that in this way it is not possible to flatten a flood wave, but only to have an insignificant impact, in terms of its flood protection effect, on the delayed high water in the earlier phase of the wave. In addition, controlling multiple devices to produce the described effect would be complicated. Figures No. 4 and 5 schematically show the relationships between Międzyodrze and flood waves.
Page 27 of 36 Figure No. 4 The floodplain area and volume for the Międzyodrze area for floods with a flow probability of Q10%
Figure No. 5 The floodplain area and volume for the Międzyodrze area for floods with a flow probability of Q1%
It was also found that the embankments surrounding the Międzyodrze area are not flood embankments. If they were to be part of a flood control structure, comprehensive modernisation would be necessary to achieve the right parameters. The final report on hydraulic modelling, containing a description of the methodology, scope of analyses performed and conclusions is included in Appendix No. 3.
Page 28 of 36 4.4. Testing of physico-chemical properties of waters and bottom sediments
Due to the identified risk of contamination of sediments in the Międzyodrze channels, surveys of seabed sediments were carried out as part of the preparatory works to determine the content of contaminants in the potential excavated material. The samples were taken from 10 spots [April 2018]. The choice of location was dictated by the possibility of obtaining a full spectrum of content of the tested substances within Międzyodrze and the possibility of determining the dependence of the amount of residues on the location. The samples were tested for the content of heavy metals and organic compounds such as polycyclic aromatic hydrocarbons and polychlorinated biphenyls. The conducted studies were preliminary in nature and their aim was to verify the information raised at the consultation stage, indicating the possibility of accumulation of hazardous substances in the Międzyodrze area. Despite the trace amounts of dangerous substances found in one of the samples taken (arsenic), the results of the tests did not confirm these concerns. However, it cannot be excluded that a large scale of sediment removal works may result in the problem of contaminants remaining in the sediments. In the case of dredging works being carried out in the area, however, it is necessary to re-examine the places where the works are carried out to determine the possible way of dealing with the excavated material. Water quality research was conducted on the basis of the results of monitoring carried out by the Chief Inspector of Environmental Protection. Complete information on the methodology and conclusions in the field of water quality testing and results of bottom sediment measurements can be found in Appendix No. 4. For analysis and inference on the condition of water quality in the Międzyodrze area data from the following measuring and control points located in individual water bodies were used:
§ The control points within the Odra River body from the Warta River to the Western Odra are the Odra River in Widuchowa, the Odra River above the Rurzyca estuary, and Odra - below Słubia estuary village called Osinów). These points are located in the upper Odra River, thanks to which it was possible to test the quality of water flowing into Międzyodrze area. § In the area of Międzyodrze itself (the water body of the Odra River from the Western Odra to Parnica) there are points: Western Odra - motorway (the village of Siadlo Dolne), from which waters are used to supply people with drinking water, Western Odra - in Mescherin, Eastern Odra - estuary to Dąbie lake(Szczecin-Most Cłowy). § Outside the Międzyodrze area, as part of the Odra water body from Parnica to the estuary, there is one point in the northern part of Szczecin at the height of Dąbie lake Western Odra - UMS Base (Szczecin).
Based on the tests carried out since 2012 at all measuring points, according to the Regulation of the Minister of the Environment of 21 July 2016. on the method of classifying the status of homogeneous bodies, surface water bodies and environmental quality standards for priority substances are classified as BAD with poor ecological potential. The main factors determining the bad mark were the biological elements. The physico-chemical elements had much better values, classifying these elements to both class I and II, but also in some cases to the class "below good potential".
Page 29 of 36 The assessment of physico-chemical elements was carried out based on the results of tests on indicators characterising the physical state, oxygen conditions, organic pollutants, acidification and biogenic conditions.
The physico-chemical analysis showed the eutrophication of waters mainly through the following indicators: ammonium nitrogen (waters flowing into Międzyodrze), nitrate nitrogen (waters flowing into Międzyodrze and waters flowing out of the Międzyodrze), nitrite nitrogen (waters flowing into Międzyodrze), and above all through phosphates, where each research year there was abnormality in the waters of the Międzyodrze, as well as in waters flowing in and out of the area. There is also a downward trend in phosphates, which gives rise to hope for an improvement in this indicator in the future.
The salinity of waters in the Międzyodrze area and in the waters flowing out of the Międzyodrze area was shown to a lesser extent. 4.5. Climate change and adaptation processes
Taking into account the scope of the planned works, which may result in a change in water conditions and the characteristics of the area in terms of greenhouse gas emissions and binding, it was necessary to analyse the potential impact on climate change. A comprehensive analysis and conclusions can be found in Appendix No. 5.
Within Międzyodrze, there is a major part of one of the largest aggregates of fluviogenous peat bogs in Poland with peat deposits and alluvial soils. On the one hand, it is a huge "warehouse" of coal withdrawn from the atmosphere, on the other hand, a source of emissions of the so-called "greenhouse gases" to the atmosphere. The nature and scale of this process depend to a large extent on water conditions and land use.
The aim of the analysis was to determine the key parameters of these resources: organic and alluvial soils, and the structure and trends of changes in time of Miedzyodrze vegetation units. Knowledge was to form the basis for the assessment of changes in greenhouse gas (GHG) emissions from the Międzyodrze soils in relation to the diversity of uses and the various levels of soil moisture.
Firstly, the water conditions related to water levels and flows (the lowest, average and maximum) determined on the basis of hydrological modelling of Odra Valley for the purposes of the flood protection project were analysed. The analysis of selected environmental parameters aimed at optimisation of activities aimed at improvement of natural conditions and protection of selected elements of nature and environment was also performed. In particular, it was about the maximum reduction of greenhouse gas emissions, counteracting decession of the peat deposit and related disturbances in functioning of the hydrological system of Odra Valley, loss of carbon resources accumulated in organic as well as organic and mineral sediments, and degradation of protected natural habitats and species.
Międzyodrze is a peatland site containing significant resources of organic carbon, so far excluded from the atmospheric circulation. The potential restoration of agricultural use of drained peat soils is associated with the risk of high greenhouse gas (GHG) emissions to the atmosphere. The area of Międzyodrze is diversified into washlands with different hydrological, soil and biocenotic conditions. The least exposed to anthropogenic pressure is southern washland (soils), then the central washland and the most exposed is northern washland. In terms of the naturalness of
Page 30 of 36 vegetation and its biodiversity, the ranking of these areas is the opposite. For several dozen years, Międzyodrze ecosystem has undergone dynamic changes. The analyses carried out showed that the Międzyodrze area is sensitive to changes in water relations, both to lowering and raising the groundwater level. Both phenomena can lead to peat soil degradation and the release of large quantities of greenhouse gases.
5. Conclusions - hydrological and natural model
Based on the studies listed in chapter 2, a hydraulic and natural model was prepared, constituting Appendix No. 6 to this Report. This study provides a comprehensive analysis of the scope for action that can be taken, including its effects and effects. On the basis of the above two groups of conclusions were formulated:
I. Międzyodrze as an element of flood safety system: 1) Międzyodrze area takes part in limiting the effects of flooding by acting as a natural floodplain, which fills up as the water level rises, taking into account the terrain (embankments, canals, terrain) and technical conditions (Widuchowa weir, locks, other technical equipment); 2) The maximum retention potential of Międzyodrze, measured by the amount of water that can be accumulated in the Międzyodrze area, is about 140 million m3 at the volume of flood waves: Q10% - 5,416 million m3, Q1% - 7,815 million m3; 3) The current state of water facilities that can be used to increase the retention potential prevents their use: § the embankments surrounding the area were devastated as a result of lack of maintenance works, resulting in the occurrence of heterogeneous height of the top of embankment, poor technical condition or loss of the embankment. The embankments are a place of occurrence of natural habitats - riparian forests, whose occurrence depends on the current of the river; § water facilities (utility and navigable locks, cofferdams, weirs), not used and unserved, have been damaged and are unable to perform their original function, i.e. regulating the flow of water; § the Międzyodrze channels, as a result of water flow limitation, become overgrown and disappear, which results in increasing the water flow limitation and accelerating the dynamics of these phenomena; 4) As activities that may contribute to increasing the retention capacity of the Międzyodrze area, the following were adopted: § modernisation of the embankment (levelling, elevation of the ordinate); § deepening and removing vegetation from selected channels, which contribute the most to limiting the possibility of water flow; § the restoration of the functioning of technical installations in order to control the flow of water; 5) Conditions, including natural conditions, influencing the possibility of achieving the expected effects: § limited area - the area is limited by two branches of the river, it is not possible to enlarge it; § embankment modernisation is limited by the occurrence of riparian forests, a habitat protected in the Natura 2000 area. This measure is also an element that
Page 31 of 36 raises objections of some natural experts, who see the existence of embankments as the main cause of negative changes occurring in the nature of the area; § cleaning the bottom (dredging) of the canals, selected in terms of achieving the assumed flood objectives and environmental conditions, can contribute to an increase in retention capacity (channel retention) by 0.7 million m3, which is an insignificant amount in terms of reducing the effects of floods; § surveys of bottom sediments in the Międzyodrze channels, including their quantity and quality, have identified possible problems during the works implementation phase related to the possibility of releasing the sediments and thus causing water turbidity in the channels and in the surrounding Międzyodrze waters of the Odra River. As a measure to minimize the negative impact, it was proposed to spread the planned works over a longer (10 years) period of time; 6) Flow control through hydrotechnical devices in Międzyodrze enables controlling and influencing the course of flood with a high probability of occurrence (10%). The impact on the flood with medium and low probability of flow is small and limited to the initial phase of the flood. At the moment when the water begins to overflow through the crown of Miedzyodrze embankments, it is impossible to control the course of the flood. The impact of the proposed activities decreases with the increase of the flood wave volume; 7) Finding the optimal control rules for the complex system that constitutes Międzyodrze together with dozens of facilities controlling water flow is a very complicated task requiring many iterations of calculations and analysis of the results obtained; 8) Significant limitations in the possibility of forcing water flow in the canals were found, which resulted from the limited impact of the damming Widuchowa weir, whose influence on the water level differences decreases with the movement in the northern direction. Lack of flow in the channels would lead to rapid loss of effect achieved by cleaning and dredging works. The occurrence of barriers in the form of communication routes (roads on embankments) dividing the area was also considered a significant limitation; Progressive eutrophication and landings with negative effects on the flow in the small and medium-sized channels of the Odra River, which may result in the complete overgrowth of the channels and may also reduce the retention capacity, both in terms of usable volume and the time at which it can be used.
II. Międzyodrze as a natural object: 1) The restoration (enabling and inducing) of the flow in the Międzyodrze canal network was considered a desirable phenomenon, both in the context of flood control activities. Enabling the flow is connected with unblocking the channels and inlet and outlet devices (purification and deepening), and inducing the flow is possible by causing a hydrological drop, including the use of the Widuchów weir and hydrotechnical devices located in the Międzyodrze embankment; 2) The lack of a steady flow and the accompanying intensive eutrophication have an adverse effect on some populations and habitats, including fish populations. At the moment, many canals are very overgrown, shallow with a bottom covered with a thick layer of silt. In the summer it causes a significant decrease in the oxygen content in water, so-called "przyducha" (lack of oxygen). Changes in the number of bird species were also found, which are related to the replacement of meadow habitats;
Page 32 of 36 3) Taking into account the diagnosed processes and their adverse impact on environmental values and the possibilities of limiting the retention potential, the scope of works aimed at their slowdown has been proposed: § cleaning of locks and other hydrotechnical objects together with sections before/after the facilities [approx. 100 - 150 m]; § improving flow conditions by cleaning selected channels of the top layer of vegetation without interfering with the bottom; § dredging of canals [understood as a phase action, performed on various scales, but including short sections of small and medium canals] - as part of the dredging process, deepening of canals with a total length not exceeding 20 km would be recommended [approx. 10% of the length of all canals in Międzyodrze area].
6. Social consultations
Międzyodrze as an area of exceptional natural values and attracting the attention of many stakeholders [not only due to the natural aspects, but also due to its tourist use and cross-border nature] caused the need to develop an individual approach to the potential investment process and to conduct a dialogue with interested parties from the earliest stages of the Project implementation.
As a result, a public consultation, going beyond the obligations of an administrative procedure, was conducted to ensure the proper preparation of the Project, while respecting the voice of individual stakeholders.
The following actions were taken as part of the structured public consultation:
§ organisation of information and consultation conferences, providing information on a regular basis about the progress of works and their results; § reporting meetings with the World Bank during the World Bank Missions § information and consultation point in Gryfino (Tourist Information Centre at ul. Nadodrzańska 1); § providing information by electronic means [e-mail]; § launch of the website [http://bs.rzgw.szczecin.pl/], on which information about the Project was collected and materials available for download, i.e.: o inventory of Międzyodrze; o hydraulic and natural model; o summary of the modelling report [language versions: Polish and English]; o presentations from the information and consultation conference - May 2018; o presentation from the 1st Project Conference - December 2018; § additional initiatives, such as the Water Round Table, organised in agreement with the Coalition Save the Rivers.
It should be concluded from the analysis of the course of consultations that Międzyodrze, as a multifunctional object, attracts the attention of various circles which have different expectations regarding the function of the area, and thus different preferences in terms of actions and expected effects planned to be carried out in Międzyodrze. The course and results of consultations are included in Appendix No. 7 to this Report. The following are the most frequently presented positions:
Page 33 of 36 1) Międzyodrze loses its natural values because it is not a living riparian forest linked to the river. The solutions proposed by the Consultant [Sweco] do not take into account the complexity of the riparian forest. Renaturalisation of Międzyodrze riparian forest - or at least a partial lowering of flood embankments - would not only restore the hydro- morphological processes necessary for the revitalization of the riparian forest, but would also be an element improving the ecological status of the watercourse [Social and Ecological Initiative Centre Stary Zagon]. 2) The situation at Międzyodrze and adjacent washlands requires improvement, also in the aspect of nature protection. Above all, regarding the enforcement of applicable laws. This applies, for example, to illegal rubbish dumps and unauthorised motorboat rides. More important than building new technical structures or embankments would therefore be to enforce what already exists [Board of the Society of Friends of the German-Polish European Lower Odra Valley National Park]. 3) It should be accepted that some hydrotechnical structures, if necessary, would have to be repaired, but no new ones should be built [Board of the Society of Friends of the German- Polish European Lower Odra Valley National Park]. 4) It would be beneficial if Międzyodrze had the status of a national park and the surrounding washlands had the landscape park status [Board of the Society of Friends of the German- Polish European Lower Odra Valley National Park]. 5) Under no circumstances should Miedzyodrze area be drained by artificial pumping of water or any other drainage method. The goal must be to maintain the year-round contact between Międzyodrze and the water levels in Eastern and Western Odra, and not to interfere with the formation of peat, and thus the binding of CO2 [Board of the Society of Friends of the German-Polish European Lower Odra Valley National Park]. 6) Suggestions - leaving Międzyodrze as it is - no interference in the water network of the area, no reconstruction of flood gates, no reconstruction of embankments - the area
perfectly fulfils its functions for flood protection and as a CO2 reservoir as well as an effective nutrient filter for the Baltic Sea [Coalition Save the Rivers ]. 7) Establishment of Międzyodrze National Park [Coalition Save the Rivers]; 8) Small tourist investments modelled on Biebrza, i.e. small paths to observation towers, canoeing, canoe with a guide, support for small agritourism investment projects in the area, as a controlled development of accommodation facilities [Coalition Save the Rivers]; 9) Limitation for large investments threatening the preservation of good condition of the environment and landscape in the present state - the main attraction of the region [Coalition Save the Rivers]; 10) Small-scale investments are possible [e.g. removal of small parts of old dikes - near the old, inactive locks], which can be characterised by benefits for both nature protection and water quality, as well as flood protection [Coalition Save the Rivers]. 11) Many years of neglect due to the lack of established active protection measures for the area of Międzyodrze over time have led to a significant natural succession of this area [Gryfino Town and Commune]. 12) Shallowing of a considerable area of Miedzyodrze canals, lack of water flows, and thus the creation of anaerobic conditions, is conducive to the impoverishment of flora and fauna occurring in the area of Międzyodrze, often unique on a European scale. This process also has a negative impact on the broadly understood tourism and attractiveness of this area for tourists and residents of Gryfino [Gryfino Town and Commune];
Page 34 of 36 13) A different approach to the protection of Miedzyodrze nature and undertaking of revitalisation activities of this area is required. Abandoning treatments that restore the patency of canals, failure to remove foreign and invasive species will result in the subsequent years of succession and shallowing [Gryfino Town and Commune]. 14)In the opinion of Gryfino Commune, the considerable importance of Międzyodrze in flood protection can not be ignored. Ensuring good state of the canals, their patency and appropriate depth in the whole area will allow Gryfino Commune to be protected against flood waters and frequently occurring backwater [Gryfino Town and Commune]. 15)Due to the fact that the hydrotechnical development of Międzyodrze is included in the voivodeship register of monuments and is indicated as an area of historic cultural value (Spatial Development Plan of the Zachodniopomorskie Voivodeship), the participation of conservation services should be taken into account when planning and implementing activities. [Provincial Monument Conservator].
7. Financial summary The sum of funds spent on preparatory work for the implementation of the Task amounted to PLN 731 848 net of tax.
8. Summary The conducted analyses show that Międzyodrze in its existing state participates in the reduction of flood effects by accepting flood water bodies as a natural flood polder. The total retention capacity of the area resulting from calculations using a hydraulic model was determined at 140 million m3, which is about 5% of the flood wave volume with a probability of occurring once every 100 years. At the same time, the results of the simulations carried out indicate that the actions that can be implemented (control by restoring the operation of hydrotechnical devices, cleaning some of the channels, repairing existing embankments) will not significantly increase the existing retention capacity. The scope of work analysed took into account potential environmental (primarily environmental) restrictions. Possible increase in retention by deepening the channels is about 0.7 million m3.
In environmental terms, it should be stated that the progressive succession and terrestrialization of river branches and canals within the Międzyodrze area are caused by a small and steadily decreasing flow (blocking the flow of water within the former locks, crossing the network of channels within the Międzyodrze area by connection fills). At the moment, many canals are very overgrown, shallow with a bottom covered with a thick layer of silt. In the summer it causes a significant decrease in the oxygen content in water, so-called "przyducha" (lack of oxygen). This adversely affects selected elements of the environment, including the population of fish and birds. This process is exacerbated by the lack of continuous flow in most of the channels and very rapid eutrophication of the Międzyodrze waters and may result in the complete overgrowth of the channels, thus reducing the total retention capacity - both in terms of usable volume and the time at which it can be filled.
During the preparatory works, in accordance with the principle of transparency, stakeholders, including natural scientists, NGOs and local communities, were kept informed about the progress of conceptual work and the conclusions drawn. At all stages, interested parties were encouraged and encouraged to express their own opinions and comments. It should be noted that due to
Page 35 of 36 different expectations in relation to the function of Międzyodrze, there is no unanimity of interested entities as to the legitimacy of taking actions in this area and its scale.
On the basis of the above mentioned analytical and research works, including broad public consultations, the following indications should be formulated:
1) Due to the lack of significant effects on flood protection, which can be achieved as a result of planned technical works, it is justified to abandon their implementation in the original scope; 2) Due to the significant importance for biodiversity and the type and dynamics of identified natural processes taking place in Międzyodrze, the possibility of carrying out maintenance works related to the restoration of water circulation should be considered. The obtained effect will also be beneficial from the point of view of maintaining the existing retention potential; 3) When developing the scope and scale of activities, the target function of the area should be defined so as to achieve the best results in relation to outlays, taking into account social, environmental and cultural aspects, by means of implemented activities. 4) The materials developed during the preparatory works should be widely publicised with the possibility of using them by the interested parties to develop area management plans and the possibility of obtaining funds for the implementation of the activities.
9. Appendices
The Final Report contains two summaries in English: Appendix 2 - file Summary results of the nature inventory for task 1A.3 and Appendix 6 - file Final report recapitulation of actions taken for modelling and nature inventory 1A.3. Other files are attached in Polish. 1) Geodetic inventory of water facilities 2) Report on wildlife inventory 3) Report on hydraulic modelling 4) Testing of physico-chemical properties of waters and bottom sediments 5) Analysis of climate changes and adaptation processes 6) Hydrological and natural model – appendix 3 Animacje, due to the format requires the use of the 7-zip program 7) Report on public consultations
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