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Singer A.,Senckenberg Institute | Singer A.,University of Bremen | Schuckel U.,Senckenberg Institute | Beck M.,Carl von Ossietzky University | And 12 more authors.
Marine Ecology Progress Series | Year: 2016

We used small-scale species distribution models to predict the past and present spatial distribution of 7 characteristic macrofauna species in response to climatic and environmental changes that have been recorded for the Jade Bay (German Wadden Sea) over the last 4 decades (1970s to 2009). Four presence-absence modelling algorithms (RF, MARS, GLM, GBM) were merged within the ensemble forecasting platform 'biomod2'. The present spatial distribution (representing 2009) was modelled based on statistical relationships between species presences, true species absences and 7 high-resolution (5 m) environmental grids. The past spatial distribution (representing the 1970s) was then hindcast in response to climate change-induced (1) sea-level rise, (2) water temperature increase and (3) seagrass recovery due to de-eutrophication. The past distribution scenario was evaluated using independent historical macrofauna data from the 1970s. Present ensemble prediction maps accurately captured the potential ecological niches of the modelled species throughout Jade Bay (i.e. good to excellent true skill statistic [TSS] and area under the receiver operating characteristic curve [AUC] evaluation measures). The predicted present macrofauna distribution correlated most significantly with hydrodynamic conditions (submergence time, shear stress) and sediment characteristics (mud content). The past distribution scenario revealed significant changes in small-scale spatial distribution patterns of the characteristic modelled species (1970s to 2009) and showed a very good match with historical macrofauna data. Climate change-induced sea-level rise and its local implications for Jade Bay (changes in topo - graphy, tidal range and submergence time), and water temperature increase explained the potential macrofauna distribution shifts over the last 4 decades. © 2016 Inter-Research.


Culmsee H.,University of Gottingen | Culmsee H.,Heritage Foundation | Schmidt M.,Northwest German Forest Research Station | Schmiedel I.,University of Gottingen | And 3 more authors.
Ecological Indicators | Year: 2014

Recent assessments have identified significant shortfalls in the current Natura 2000 network approach for identifying protected areas throughout the European Union. A more systematic conservation network planning approach that adopts strategic development options and considers the occurrences of species and habitats within the distribution ranges of species across larger areas is needed in order to support decision making processes on the potential expansion, establishment and/or maintenance of conservation areas. Using high-nature-value forest habitats across a large test region, i.e. the state of Lower Saxony in Germany, we developed a method aimed at systematically locating and appraising temperate forest habitats using indicator species distribution maps. Forest community indicator species were determined using forest habitat affinity criteria (derived from an existing database) and community fidelity (based on a review of 5338 vegetation relevés). Known habitat occurrences were derived from habitat surveys and relevant literature and were related to model data on indicator species distribution on a grid of 1739 raster cells (each 30 km2) using logistic regression. The predictive power of the distribution models increased with the number of indicator species. However, tight correlations between indicator species distribution and habitat occurrence were only found when indicator species with a high affinity to forests were used exclusively. Field inspection of grid cells with outlying occurrences of five upland forest communities revealed several new forest habitat locations and led to greatly improved distribution models. We conclude that the distribution of high-nature-value forest habitats can be predicted from large-scale raster data on plant species distributions when only indicator species with close association to forest habitats and a high fidelity to a single community are selected. Our approach may therefore facilitate a review of the existing Natura 2000 forest conservation network, be used to identify additional conservation areas or to monitor the success of forest conservation management measures. © 2013 Elsevier Ltd. All rights reserved.


Thorenz F.,Coastal Defence and Nature Conservation Agency NLWKN | Blum H.,Coastal Defence and Nature Conservation Agency NLWKN | Kortenhaus A.,TU Braunschweig
Proceedings of the Coastal Engineering Conference | Year: 2012

The sandy barrier island of Baltrum is located in the north-western part of the German Federal State Lower Saxony in the North Sea. The north-western part of the island is protected by a dune revetment against storm surges and erosion. In order to determine the functionality and loading of the construction under design storm surge conditions and investigate planning alternatives, numerical modeling of sea state conditions in combination with hydraulical model tests for the construction were executed. Measured overtopping rates of up to 125 l/(s.m) and loads up to 150 kPa showed the necessity to strengthen and heighten the initial construction. A combination of wall elements for wave run-up and overtopping reduction in combination with a crest wall were designed in order to meet the technical demands of coastal defence as well as the touristical needs of an important recreation locality.


Gruhn A.,TU Hamburg - Harburg | Salecker D.,TU Hamburg - Harburg | Frohle P.,TU Hamburg - Harburg | Schuttrumpf H.,RWTH Aachen | Thorenz F.,Coastal Defence and Nature Conservation Agency NLWKN
Proceedings of the Coastal Engineering Conference | Year: 2012

Low lying coastal areas have always been preferred settlement areas as well as trading and industrial areas. Unfortunately, those areas are strongly endangered by extreme storm surges. In the event of a flood defence failure, protected areas are flooded and damages have to be expected. For the assessment and management of flood risk, the European Union approved the "Directive of the European Parliament and the Council on the assessment and management of flood risk". As one part of a risk and damage analysis the risk of flooding - being the product of failure probability of a certain flood defence and the damages resulting from a failure of this flood defence - has to be determined. One possibility for the assessment of the failure probability is provided by fragility curves. A method for the derivation of fragility curves for flood defence dunes is described. Hence, the applied dune erosion model as well as the method for the derivation of the required input data is explained. Furthermore, first results of the calculation of failure probabilities and fragility curves are presented.


Gruhn A.,TU Hamburg - Harburg | Salecker D.,TU Hamburg - Harburg | Frohle P.,TU Hamburg - Harburg | Schuttrumpf H.,RWTH Aachen | Thorenz F.,Coastal Defence and Nature Conservation Agency NLWKN
6th Chinese-German Joint Symposium on Hydraulic and Ocean Engineering, CGJOINT 2012 | Year: 2012

Low lying coastal areas have always been preferred settlement areas as well as trading and industrial areas. Unfortunately, those areas are strongly endangered by extreme storm surges. In the event of a flood defence failure, protected areas are flooded and damages have to be expected. For the assessment and management of flood risk, the European Union approved the "Directive of the European Parliament and the Council on the assessment and management of flood risk". As one part of a risk and damage analysis the risk of flooding - being the product of failure probability of a certain flood defence and the damages resulting from a failure of this flood defence - has to be determined. One possibility for the assessment of the failure probability is provided by fragility curves. A method for the derivation of fragility curves for flood defence dunes is described. Hence, the applied dune erosion model as well as the method for the derivation of the required input data is explained. Furthermore, first results of the calculation of failure probabilities and fragility curves are presented.


Bachmann D.,RWTH Aachen | Grimm C.,RWTH Aachen | Frohle P.,TU Hamburg - Harburg | Thorenz F.,Coastal Defence and Nature Conservation Agency NLWKN | Schuttrumpf H.,RWTH Aachen
6th Chinese-German Joint Symposium on Hydraulic and Ocean Engineering, CGJOINT 2012 | Year: 2012

On February 16th 2012 the German public commemorates the 50th anniversary of the North Sea flood of 1962. Over 340 people died and approx. 28,000 apartments or houses were damaged. Since 1962 huge efforts were made and a lot of money was spent on coastal protection measures in northern regions of Germany. Nevertheless, the expected global climate change and the resulting acceleration of sea level rise require a re-evaluation of coastal protection measures and flood risk management strategies for coastal regions. The practical realisation of risk adaption and mitigation is a major task for coastal authorities. The development of methods and computer based tools to support this process is one of the major challenges for research. Therefore, the Institute of Hydraulic Engineering and Water Resources Management of RWTH Aachen University developed the software package PROMAIDES. It integrates modules for reliability analysis, hydrodynamic analysis, analysis of consequences as well as the combining risk analysis. This paper focuses on the adaption of the PROMAIDES system for an application to coastal regions. The development process and the verification on selected study sites is part of the HoRisK-project, presented in this paper.


Vennebusch M.,Leibniz University of Hanover | Albert L.,Leibniz University of Hanover | Schon S.,Leibniz University of Hanover | Kube F.,Leibniz University of Hanover | And 4 more authors.
Record - IEEE PLANS, Position Location and Navigation Symposium | Year: 2012

For many water engineering tasks, precise information about the water flow characteristics is required to model discharge and sediment transport. In many cases, the Global Positioning System (GPS) is used to measure floater trajectories and to derive flow velocities indirectly from floater positions. In this paper, we describe a new GPS-based measurement system that avoids the use of expensive equipment and which uses a direct velocity determination approach. Despite its low costs, the new floater system achieves position accuracies of several meters and accuracies of about 5 cm/s for velocities. We describe both hardware and software details of the new system. Results from a first measurement campaign show the system's capabilities for hydrometric applications. © 2012 IEEE.

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