The morphology of the Wadden Sea is constantly changing due to tidal current, other natural impact and anthropogenic activities.
Tidal flats are important feeding, roosting and/or moulting areas for birds at low tide and are also important habitats for seals, fish and shrimps. The high biological productivity of the tidal area sustains a high number of birds and fish and also offers advantages for fisheries.
Tidal flats are a habitat for several species which require a broad spectrum of sediment types. Due to changes in the sea level, the sediment composition of the tidal flats may change and would influence the benthic communities. Amongst others, human activities like fisheries may also alter the sediment composition of the tidal flats.
In the TMAP it is necessary to document dynamic and trendwise changes in the morphology of the Wadden Sea in order to obtain sound basic information in all three countries which can be used to assess whether these changes may result from anthropogenic activities.
Trilateral policy and management aims “to achieve, as far as possible, a natural and sustainable ecosystem in which natural processes proceed in an undisturbed way” (Guiding Principle).
With respect to the “Tidal Area the following Target applies (Wadden Sea Plan):
Monitoring of geomorphologic characteristics of the Wadden Sea is carried out to assess possible changes due to changes in climate (e.g. sea level rise, increase of storms) and the effect of these changes on the habitats, species and communities.
WSP
Targets on Tidal Area:
HD
Monitoring of geomorphological features for habitat types in the Tidal Area:
Favorable conservation status of habitat types:
WFD
Article 8
Annex V, Chapter 1.2.3 and 1.2.4: Morphological conditions
OSPAR
No specific requirements for geomorphological monitoring.
Tidal flats
Tidal flats are defined as mudflats and sandflats not covered by seawater at low tide (EU Habitats Directive) between Mean High Tide Level (MHTL) and Mean Low Tide Level (MLTL);
Sediment type
| Sediment type | % clay (<2µm) | % silt (2-63 µm) |
| Sand | < 5 | < 10 |
| Mixed | 5 - 8 | 10 - 50 |
| Mud | > 8 | > 50 |
(after Dijkema, 1987)
Monitoring of geomorphologic characteristics in the TMAP is carried out to assess possible changes due to changes in climate and the effect of these changes on habitats, species and communities. Information on area of tidal flats and sediment type distribution can be obtained from remote sensing surveys and in combination with existing field sampling (such as benthos monitoring).
(Table 5.1) Parameters with monitoring locations and frequencies and the relation to the other monitoring requirements.
| Parameters | Description | Location | Frequency | Method | WFD | BD/HD | OSPAR | OTHER | Remark |
| Mandatory TMAP parameters | |||||||||
| Area (tidal flats) | Size and location (km²) | Entire area | 6 years | Ground truth and/or remote sensing | X | X | - | - | - |
| Sediment type distribution | Location and area of sediment types (sand, mixed, mud) | Entire area and/or selected sites | 6 years | Ground truth and/or remote sensing | X | X | - | - | - |
Remarks:
5.1 Parameters
5.2 Monitoring locations
For each of the four region (The Netherlands, Niedersachsen/Hamburg, Schleswig-Holstein, Dennmark), at least one sampling location per WFD water body type should be established as appropriate.
Ground truth and/or remote sensing methods or other appropriate comparable method should be applied (see also HARBASINS 2006).
Several methods are used in the countries to monitor extension of tidal flats and sediment types for various purposes. The derived data can be regarded information is comparable for the Wadden Sea area.
Remote sensing methods (optical satellite sensors) have been applied on project basis (OFEW, 2006 & 2007) but has not yet made operational for regular monitoring.
OSPAR has developed a set of common assessment parameters and their corresponding area-specific assessment levels to complement the Common Procedure. Macroalgae are assessed as Category II: Direct effects of nutrient enrichment.
In the WFD, a CIS guidance document has been prepared which focused particularly on harmonization of assessment methods and criteria across European water policy (CIS, 2005).
For the Wadden Sea, coverage of green macroalgea (entire intertidal area) and biomass of main species/general (selected sites) are regarded as suitable assessment parameter. The assessment hast to take into account that there is no apparent direct temporal and spatial relation between macroalgae development and nutrient loads (Beusekom et al. 2005).
| Parameter | Assessment / Objective | |
| Area of tidal flats | km² | Stable or natural fluctuation |
| Sediment type distribution | km² of types per sub-area (tidal basin, region) | Stable or natural fluctuation |
In the framework of the preparation of trilateral reports or a QSR, the requested information should be made available by the responsible authorities: tables with information about changes in occurrence, distribution and size of sediment types of tidal flat areas (including GIS data).
The information should be reported at least every six years to the national TMAP data unit (according to the national regulations) to be available for trilateral assessments (see TMAP Data Handling Manual).
Appropriate Quality Assurance (QA) activities should be in place and reported together with information about applied methods.
Danmarks Miljøundersøgelser (DMU, NERI)
Miljøministeriet, Miljøcenter Ribe
Kystinspektoratet Lemvig
Landesamt für Natur und Umwelt (LANU)
Landesbetrieb für Küstenschutz, Nationalpark und Meeresschutz (LKN)
Niedersächsischer Landesbetrieb für Wasserwirtschaft, Küsten- und Naturschutz (NLWKN)
Bundesamt für Seeschifffahrt und Hydrographie, Hamburg (BSH)
Rijkswaterstaat Waterdienst Lelystand
Rijkswaterstaat Noord, Leeuwarden
HARBASINS 2006.: Workshop on Remote Sensing of Intertidal Flats. Presentations and Practical Exercises. Brockmann Consult and Common Waddden Sea Secretariat. Proceeding of a workshop at the Geesthachter Innovations- und Technologiezentrum (GITZ), 11 - 12 September 2006
HARBASINS, 2007.: Synergies in WFD implementation in the Wadden Sea. HARBASINS TMAP workshop, October 2007.
OFEW 2007.: Operationalisierung von Fernerkundungsmethoden für das Wattenmeermonitoring. Brockmann consult, July 2007