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The European Flood Risk Management Directive (FRMD) came into force on October 23, 2007. The results of the initial working steps in the implementation of the directive and the Lower Saxon approach to the development of the FRM plans will be presented.

Folmer E.O.,Netherlands Institute for Sea Research | Drent J.,Netherlands Institute for Sea Research | Troost K.,Institute for Marine Resources and Ecosystem Studies | Buttger H.,BioConsult SH | And 6 more authors.
Ecosystems | Year: 2014

Intertidal blue mussel beds are important for the functioning and community composition of coastal ecosystems. Modeling spatial dynamics of intertidal mussel beds is complicated because suitable habitat is spatially heterogeneously distributed and recruitment and loss are hard to predict. To get insight into the main determinants of dispersion, growth and loss of intertidal mussel beds, we analyzed spatial distributions and growth patterns in the German and Dutch Wadden Sea. We considered yearly distributions of adult intertidal mussel beds from 36 connected tidal basins between 1999 and 2010 and for the period 1968-1976. We found that in both periods the highest coverage of tidal flats by mussel beds occurs in the sheltered basins in the southern Wadden Sea. We used a stochastic growth model to investigate the effects of density dependence, winter temperature and storminess on changes in mussel bed coverage between 1999 and 2010. In contrast to expectation, we found no evidence that cold winters consistently induced events of synchronous population growth, nor did we find strong evidence for increased removal of adult mussel beds after stormy winter seasons. However, we did find synchronic growth within groups of proximate tidal basins and that synchrony between distant groups is mainly low or negative. Because the boundaries between synchronic groups are located near river mouths and in areas lacking suitable mussel bed habitat, we suggest that the metapopulation is under the control of larval dispersal conditions. Our study demonstrates the importance of moving from simple habitat suitability models to models that incorporate metapopulation processes to understand spatial dynamics of mussel beds. The spatio-dynamic structure revealed in this paper will be instrumental for that purpose. © 2014 The Author(s).

Haberlandt U.,Leibniz University of Hanover | Belli A.,Leibniz University of Hanover | Holscher J.,Niedersachsischer Landesbetrieb fur Wasserwirtschaft
Hydrologie und Wasserbewirtschaftung | Year: 2010

Trend analyses have been carried out with observed time series of temperature and precipitation in Lower Saxony. The investigations are based on daily data from 18 temperature stations and 263 precipitation stations in the time period from 1951 until 2005. The trends were studied separately for the winter, spring, summer and autumn seasons as well as for the whole year. Specific indices like maximum 5-day rainfall sum, maximum number of consecutive dry days etc. were used here to address especially the behaviour of extreme values. The Mann-Kendall-Test was applied to detect trends and the linear regression to assess its magnitude. Temperature showed significant positive trends in all seasons without spatial differences. In winter significant positive trends were found in precipitation, especially in the northern and southern parts of Lower Saxony. In the summer season, significant positive trends were detected in the duration of dry spell especially in the central region of Lower Saxony. The correction of precipitation regarding systematic undercatch led to a certain reduction in the number of significant positive winter trends, but did not change the overall picture.

'Favourable conservation status' is a key concept in Habitats Directive implementation. In Germany it is assessed according to the Pinneberg Scheme using three criteria: 'Structures', 'Species' and 'Adverse effects'. Based on theoretical principles of assessment and on fictitious examples of habitats the paper discusses whether these criteria and assessment.

Kreibich H.,German Research Center for Geosciences | Meyer S.,Niedersachsischer Landesbetrieb fur Wasserwirtschaft | Diekkruger B.,University of Bonn
Hydrologie und Wasserbewirtschaftung | Year: 2011

Severe damage due to high groundwater levels occurred during and after the 2002 flood in the city of Dresden, Germany. So far, damage caused by high groundwater levels has rarely been considered in flood risk analysis. However, reliable damage models are necessary to evaluate the cost-effectiveness of mitigation measures and to support a comprehensive risk management. Therefore, the "Flood Loss Estimation Model for the private sector" FLEMOps was further developed for modelling damage due to high groundwater levels. FLEMOps is empirically based and considers several damage influencing factors. In addition to the water depth, information on the building type as well as the level of precaution and contamination are also taken into account. FLEMOps for groundwater flooding has been successfully validated at the micro- and meso-scale and a sensitivity analysis has been implemented in Dresden.

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