Exploitable results A classification scheme for intertidal mudflats A typology was established based on the observed qualitative characteristics of a wide range of mudflats, as well as examples from the literature (Dyer, 1998). This was tested by application to an intertidal bank in the Scheldt Estuary, and gave reasonable results when an energy dissipation term was included. For a more quantitative and less subjective classification, a database of mudflat characteristics was established. A total of 18 mudflats were quantified in terms of twenty different variables describing physical characteristics, sediment properties and biological attributes. The results were analysed by correlation analysis, multidimensional scaling and cluster analysis to find a classification scheme describing similarities between them. Five levels of separation were found. Tidal range separated mudflats into hypertidal (>6m range), meso/macrotidal (2-6m) and microtidal (<2m). This was followed by an exposure index, separating mudflats with high and low exposure. Mudflat slope separated low slope mudflats (<0.04), high slopes (>0.04) and very steep slopes (-0. 16). For the largest group of meso/macrotidal mudflats, dry density separated mudflats with low density (<600kg/m3) from intermediate density (600-1000kg/m3) and high density (>.1000kg/m3). The biological characteristics were also examined by analysis of the occurrence of species in three mudflat zones. There were strong relationships for the upper zone, but no significant relationships for the other zones. The published classification, together with the typology, will provide a framework for the description of other mudflats. It will allow comparison and generalization, which will benefit prediction, since similar processes can be assumed active in the different types. The classification provides a means of establishing the relative importances of different process. A database of the properties and measurements on mudflats The main objective of the INTRMUD data base is to combine all data of the partners of the project and make it easily accessible to the participants thus optimising and archiving project results. In this way existing and new data can be combined to give a range of conditions that is larger than what can be achieved by each of the participants separately. Subsequently, the data can be used to understand natural processes and to develop models. The data base has been set up as a Microsoft Access (Version 7) single user application, which means that it runs on PCs using Windows 95 or Windows NT 3.51 (or higher). It offers export facilities to Microsoft Excel for analysis and graphical presentation and it has no run-time fee for users. The nature of the data stored as part of the INTRMUD project falls in one of the following groups:' - General information on dataset identification, geographical area, date, availability, owner,instruments and parameters (so-called EDMED form). - Fieldwork Activity Forms describing the type of measurements and conditions during the field survey. - Separate Data Sheets containing the actual measured values of physical and biological parameters. - A Data Sheet regarding the classification of mud flats. To keep the size and accessibility of the data base within practical limits only processed data have been stored. However, information on the original data (name data set, owner, storage medium) can be extracted from the data base. Presently, more than 200 EDMED forms and associated data sheets have been incorporated in the data base. The data base can be ordered through the Project Coordinator or by contacting Delft Hydraulics (email: Aart.Vermetten@wldelft.nl) against minimal costs. Knowledge of processes and interactions, and algorithms. The overall conceptual model for the shape adjustment of mudflats to storms is for the calm weather situation of landward transport by sequential erosion and deposition during the tide to be reversed. Calm weather causes landward sediment transport leading to soft, organic rich sediment on the upper mudflats. This is stabilized by surface growth of diatoms. With high onshore winds the waves erode the sediment and it is transported offshore. The erosion is limited by the higher density more resistant material beneath. Consequently, it is the physical processes that are dominant in the mudflat behaviour. Nevertheless, a crucial part of the sediment response to the hydrodynamics is the degree to which the diatom population, 'which is itself controlled by grazing, enhances the cohesive properties of the sediment. There are strong seasonal variations created by storms and in biological processes. Essential controlling feedback is provided by the presence of bedforms. These create frictional resistance to the flow, concentrate the flow on areas of the highest threshold for erosion, and provide a spatial heterogeneity in the biology that is essential to the ecosystem dynamics. Also the channels are important in the cross shore sediment transport. The biology influences the amount and the character of the material in suspension, which itself affects the primary production and the mud properties. For a future scenario of rising sea level it appears that transport of sediment towards the upper mudflats and the salt-marshes is likely, provided the weather does not become stormier. Thus the profile will move landwards. If there are hard backing defences to limit the transgression, the limited area for deposition may affect the amount of deposition, and cause additional erosion of the lower mudflats. If increasing storminess occurs, the enhanced off shore transport will cause erosion and a steepening of the profile. For a warming of the climate, increased cohesion created by the enhanced diatom production will be largely offset by increased razing, but some increase in sediment stability should result. For colder winters there would be a change in the biological communities and a decrease in the diatom production, leading to erosion. Ice-rafting of sediment may then become an important means of shorewards transport. The results have been published for anyone to incorporate in their future research and development. The field data are available through the database. Searching for OpenAIRE data... There was an error trying to search data from OpenAIRE No results available
