Project part-financed by the European Union (European Regional Development Fund)

The Interreg IVB North Sea Region Programme

The authors are solely responsible for the content of this report. Material included herein does not represent the opinion of the European Community, and the European Community is not responsible for any use that might be made of it.
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Management measures analysis and comparison


by S. Saathoff, J. Knüppel, S. Manson & A. Boerema

7b. Results

Compilation of measures within the TIDE estuaries

The database on management measures and further documentations on applied management activities within the TIDE estuaries have been integrated in the TIDE toolbox. Overall, the compiled information gives a broad overview on various management activities, covering all TIDE estuaries and estuarine zones.

Database on management measures
The management measure database contains at present (state 03/2013) the information on those 39 measures being analysed within this study. For each measure there is a factsheet which contains a description and evaluation of the measure following a unique scheme which includes information regarding e.g. location, status, responsible authorities, initial management objectives, description of construction work, specific boundary conditions, costs, etc.  The measure factsheet also contains evaluation results, as there is information on the degree of target achievement, synergies and conflicts with regard to ecosystem services, Water Framework Directive and the Birds and Habitats Directive. The location and design of each measure is visualized by pictures and maps.
The measures within the database represent a diverse spectrum of development targets; for example they refer to the reduction of tidal energy, range and asymmetry, to flood protection and the improvement of morphological conditions, to the development of habitats, natural gradients and processes, to the protection of species, to the reduction of pollutant loadings and the improvement of oxygen conditions.

Further documentations on TIDE management measure studies
Within the Tide project a couple of pilot projects have been undertaken at the estuaries of Elbe, Humber, Scheldt and Weser. They deal with management measure issues which are of particular concern at the specific estuary but which provide valuable experience for other estuaries. These studies refer e.g. to the revitalization of anabranches, to the morphological management of estuaries, to the alternative use of dredged material.
The development of dredging volumes, the handling of polluted sediments as well as dredging and relocation strategies have been documented within four estuary specific studies on sediment management at Weser, Elbe, Scheldt and Humber. An overall fifth study compares the different approaches on sediment management, presents examples of good practice, elaborates demands and opportunities, and at least give recommendations.
All reports are available in the TIDE toolbox.

Planning and implementing management measures: Résumé

The reasons for planning a management measure may be manifold, e.g. the demand for compensation, the requirement for improvement referring to the objectives of the WFD and Natura 2000, or a low performance and productivity of the estuarine system with regard to other deliveries for society. Nevertheless - for making measure planning and implementation successful attention should be paid to some crucial aspects. 

Conception, planning
The overall success of a management measure depends on the possibility to meet specific development targets. In order to plan a target-oriented measure and to minimize the risk of failing, each measure should start with planning a systematic and comprehensive analysis of the actual status and the requirements and potentials for improvement. Current and target state have to be determined as accurately as possible and necessary, as well as the dominant counteracting factors (e.g. pressures and impacts on the estuarine functions) and other boundary conditions hindering or supporting target achievement. Based on this analysis process, development targets and measures can be selected and prioritized. In principle, these targets should be concrete, measurable and achievable within the context of the project (IECS 2008). In order to improve the implementation chances for management measures, already in the planning phase estuary mangers should analyse the potential co-benefits and synergies as well as conflicts that are derived from the respective measure (see following chapter).
Nonetheless, management in estuaries has to deal with the dynamic and complex environment which means a particular challenge for measure planning and realization. Biotic and abiotic factors of the estuary interact constantly. For a successful management measure, the development targets have to be in accordance with what can be expected to develop into the long-term environment. Hence it is recommended to formulate dynamic goals with a time trajectory that corresponds to the perceived and predicted changes in the project area and in the estuary. That implies that the goals do not only contain a qualitative description of the desired situation (eg. which habitat types and which species communities), but also a time frame to reach the target.
Formulating dynamic goals (eg. marshland with creek development) has to follow from the understanding of both the ecological and the hydro-morphological changes. Because of interlinking physical, chemical and biological processes within a highly dynamic environment influences the measure development at a site specific location. The character of an estuarine habitat will therefore inevitably change. The goals of restoration projects for example, should be formulated with the ecological and the hydro-morphological (desired and undesired) changes in mind because they are intrinsic aspects of natural estuarine habitats. This means that it is advised to target certain habitat types/surfaces and species communities for example, but to be realistic and to a certain degree flexible regarding goal state and time scale.
An overall rule for designing measures should be to minimise land manipulation and work with the existing topography as far as possible, to use the natural resources from the site and to maximise the advantage from natural physical and biological processes. Hence, the most important rule for successful management is to work with the system, not against it!
To optimise the success of the management measures it is recommended to start in the planning phase with incorporating lessons learned from previous and on-going projects. Existing and on-going projects in similar conditions could be used as reference to estimate the evolution of habitat development and to determine feasible performance criteria for different habitats. The general knowledge on how to develop realignment sites for example, has already been greatly advanced through practical experiences in many case studies.

Realization: Use of synergies
The Water Framework Directive and the Birds and Habitats Directives represent environmental directives of the European Union. Since EU member states are legally obliged to reach the related objectives, responsible governments and subordinated administrations necessarily have a strong interest in designing and supporting targeted management measures. In order to bring forward measures in favour of the ecosystem, it is worthwhile for estuary managers to make some efforts to prove, map and communicate potential positive measure effects in view of WFD and Natura 2000 aims.
The vast majority of TIDE measures was not designed to meet the requirements of WFD and Natura 2000. However, two simple approaches to roughly evaluate potential positive and negative effects in view of WFD and Natura 2000 were described and executed on a case-by-case basis.
Measure effects in terms of WFD aims were estimated based on identifying the main WFD pressures the different estuary zones are affected by. Building on the hypothesis that positive or negative measure effects in view of the main pressures may result in positive or negative impacts regarding WFD quality elements, potential synergistic effects and conflicts were indicated and briefly described. As anticipated, the analysis showed that especially measures assigned to measure category ‘Biology/Ecology’ with habitat, species or process related development targets are supposed to have very positive or positive effects since they show large intersections with the main pressures derived from the state indicators (e.g. “Habitat loss and degradation during the last 100 years: Intertidal” and “Habitat loss and degradation during the last 100 years: Subtidal”). The average percentage of pressures positively influenced by measures of category ‘Biology/Ecology’ amounts to 67 percent. But also for measures of category ‘Hydrology/Morphology’ e.g. aiming to reduce tidal pumping effects or to improve morphological conditions, several positive effects in view of the main pressures were stated. Here, the average percentage of pressures positively impacted amounts to 21 percent (for details of the calculations see chapter
The evaluation of potential synergistic effects and conflicts in view of Natura 2000 was based on a comparison with Natura 2000 objectives defined for certain spatial units and/or conservation objectives formulated for the entire tidally influenced river sections of Weser, Elbe, Humber and Scheldt (e.g. conservation objectives for operational areas and according to the Integrated Management Plan Weser (NLWKN, SUBV 2012)). Although the estuary specific evaluation proceedings differ slightly depending on availability and spatial reference of Natura 2000 conservation objectives, potential synergistic effects were stated for most management measures considered. Analogous to the results of the WFD evaluation, the analysis showed that especially measures of category ‘Biology/Ecology’ are supposed to have positive impacts on the conservation objectives. The average percentage of objectives positively or very positively effected by the measures amounts to 78 percent, while the average percentage according to measures of category ‘Hydrology/Morphology’ amounts to 16 percent.
Another approach developed and executed in this study in order to estimate and describe potential impacts of management measures on the estuarine ecosystem is derived from the concept of ecosystem services which was refined and applied to the TIDE estuaries by JACOBS 2013. In the frame of the measure analysis, potential measure impacts on ES as defined by JACOBS 2013 were estimated considering the development targets of the TIDE measures and the surface and quality change of habitats due to measure implementation. Since most of the TIDE measures are biodiversity-targeted and examples of good practice, the expected impact especially on supporting and habitat services is positive for most measures. Also, the TIDE measures generate overall many co-benefits, i.e. a positive expected impact on many ES which were not targeted.
In order to improve the implementation chances for effective future management measures in favour of the ecosystem, estuary mangers should analyse potential synergistic effects and conflicts regarding WFD and Natura 2000 aims as well as the expected impact on ecosystem services.

Management measures generate many ecosystem services and many synergies, but also conflicts between different stakeholders could occur. An effective, clear, honest and early communication with administrations in charge, affected private individuals, stakeholders and the public is a key aspect in developing and implementing a management measure concept. Hence it is recommended to allow sufficient time for negotiations with landowners/users (e.g. with regard to agriculture, hunting, fisheries, recreation), for communicating safety concerns, for explaining and - if applicable – adapting the design of the measure.
It is recommended to communicate the findings of benefits and – moreover – of not-targeted co-benefits (ES, WFD, BHD) to stakeholders, responsible administrations, politicians and the broad public. As a result, the willingness to participate, pay and support the measure implementation, but also the general acceptance of respective projects could be increased. In the frame of this study, three possible approaches for the estimation of measure impacts were developed and tested on a case-by-case basis which could be used as a starting point for practical application.

Accompanying management and monitoring
Adaptive management, both during and after implementation, form an important part of the management strategy to improve the overall success of the management measure. Adaptive management depends on a monitoring program being suitable to identify unwanted changes or a lack of change in certain aspects for which interventions may be required to steer the development in the aimed direction (IECS 2008). Last not least, the monitoring has to deliver the basis to check whether the targeted results finally have been achieved.
The measure analysis realized in the frame of this study included a rough estimation of the degree of target achievement which was mainly based on expert judgment and monitoring or modeling results. Partly, insider knowledge of people was considered who were involved in the planning and implementation process but not mentioned in available reports. For the majority of the TIDE measures, the defined development targets and the way they are reflected in the available monitoring reports did not turn out to be usable instruments to come to a sound statement on the measure success due to the following reasons:
  • In most cases, the monitoring targets are not formulated specifically enough to be scientifically proven in the course of monitoring programs.
  • As a consequence, monitoring reports often do not explicitly refer to the available development targets.
  • Additionally, the structure of the monitoring program is regularly determined and structured by the different ecosystem components that are taken into account (e.g. flora, fauna, water quality) and not by the development targets that should be proven.
To sustainably improve the success of management measures managers should pay enhanced attention to the implementation of a specific target oriented measure monitoring. Previous and on-going projects could help to identify which factors are important to monitor, as well as identifying which monitoring techniques should be used. At least, the informative value of this monitoring might considerably increase when the program is well linked to an integrated and representative estuary monitoring.
The time-scale of the monitoring program has to follow the time-frame of the project and hence of the development goals. Nonetheless, it might be appropriate to get information on the further development of the site. In this case it should be proven if the measure monitoring or parts of the program could be continued in the context of the regular estuary monitoring.

Analysis and assessment
In order to check whether the targeted goals have been achieved the monitoring data have to be systematically analysed and assessed. If the targets have not or have only been partly achieved it has to be proven if improvements within the measure design would be possible and constructive or if the goals would be achievable by means of other measures. If the targets are not achievable, in the end it has to be checked which consequences must arise from it for the overall management within the estuary.

Publication, exchange of experience
For successful implementation of future measures it is crucial to further enhance the knowledge on estuary functioning and good practice of measure implementation. In order to progressively improve the effectiveness of measures in estuaries, estuary managers should make sure that an evaluation of the measure success in terms of lessons learned takes place and the results will be made available to other estuary managers/other organisations.

There are various challenges in planning and implementing successful management measures in estuaries. Hence, the success of several measures depends, among many others factors, on the induced sedimentation and erosion processes (Vandenbruwaene et al. 2011) because these processes are key factors in achieving most development goals, i.e. to ensure a site is sustainably providing habitats with certain water depths and velocities or receives sufficient tidal inundation for habitat development and for flood storage capacity. However, the real sedimentation and erosion processes on the site are not always in alignment with the development goals. When sedimentation rates are higher or lower than expected this could be a disadvantage for certain goals. Reduction of the sedimentation rate within a the realignment site for example, could be beneficial to meet a target for flood water storage and additionally this could also reduce the need for maintenance efforts in the future which is then beneficial for vegetation, fauna and water structures.
This study illustrates with regard to managed realignment measures that by considering certain aspects of the site selection and design, the expected sedimentation and erosion processes could be manipulated to a certain extent in favour of specific development goals. Furthermore, the conclusions from this study could be used as guideline for appropriate site selection and design (e.g. habitat development and/or safety). A crucial point is to take use of the natural physical and biological processes and to work with the system (see above). For many realignment sites the development goals are however a combination of the development of different habitat types. It is therefore recommended to adapt the design of different zones of the site in favour of the different goals. This means a large spatial variation in elevation, slope, etc. and corresponding requirements for land area.

The evaluation of previous and on-going projects will provide valuable information on the short- and long-term development of management measures and minimise the risk of associated problems. This could also help to understand the impact of management interventions on overall development, and this can indicate which other tools are required to guide restoration projects towards their goals (IECS 2008). Exchange of experiences, also across estuaries is hence necessary to improve the overall success of management measures,  and this TIDE report aims to be one step in that direction. One product of this work is the management measure database. The continuous extension of this database or a follow-up product (especially filled by current and future projects) might seriously further the process of exchange of experiences.
Feasibility and success of several measure approaches, especially those referring to the dominant pressures and impacts, depend on an in-depth understanding on estuary functioning and, in the end, on the question if estuary management will have the ability to limit and partly trace back these impacts.
Vice versa, the specific management measure shall and can contribute that the estuary obtain respectively regain its performance and productivity. This study worked out that management measures besides the targeted benefits mostly provide a couple of co-benefits for the society and the estuarine environment which can be visualised, e.g. by applying the ecosystem services concept.

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Important to know

Reports / Measures / Tools

Report: Management measures analysis and comparison

Management issues

How and by which management measures can tidal amplification be reduced?
How can public acceptance for management actions be increased?
How can the Ecosystem Services Approach be used to support management decisions?
How can we assure accessibility to an inland estuarine port without affecting the habitats and safety against flooding?
How can we prevent excessive degradation or loss of tidal marshes?
How does habitat management affect the supply of ecosystem services?
What are the key areas of conflicts or synergies in TIDE estuaries?
What are the restoration opportunities for side branch systems and river banks (e.g. left side branch Weser)?
What factors determine the distribution of suspended sediments in an estuary?
What measures are successful for the dissipation of tidal energy?
What monitoring is required to support and assess management decisions?
What parameters should be used to define and evaluate measure targets?
What tool is available to help manage multiple users of a resource in an integrated way (i.e. achieving more holistic management)?
Which aspects do I have to take into account in order to make a measure a success?
Which measures are suitable to achieve specific ecological targets?
Which measures are suitable to achieve specific morphological and hydrological targets?
Which measures are suitable to identify, protect or develop valuable submerged habitats e.g. mussel beds and Sabellaria reefs?
Which measures are suitable to improve the physical characteristics and chemical water quality?
Which measures are suitable to provide ecosystem services and benefits?
Which synergistic effects and conflicts can be expected by planning and implementing a certain measure?
“Working with nature”: What are the opportunities for sediment management in estuaries?