Time filter

Source Type

Hørsholm, Denmark

Gregersen I.B.,Technical University of Denmark | Madsen H.,DHI | Rosbjerg D.,Technical University of Denmark | Arnbjerg-Nielsen K.,Technical University of Denmark
Water Resources Research | Year: 2013

Changes in the properties of extreme rainfall events have been observed worldwide. In relation to the discussion of ongoing climatic changes, it is of high importance to attribute these changes to known sources of climate variability. Focusing on spatial and temporal changes in the frequency of extreme rainfall events, a statistical model is tested for this purpose. The model is built on the theory of generalized linear models and uses Poisson regression solved by generalized estimation equations. Spatial and temporal explanatory variables can be included simultaneously, and their relative importance can be assessed. Additionally, the model allows for a spatial correlation between the measurements. Data from a Danish rain gauge network are used as a case study for model evaluation. Focusing on 10 min and 24 h rainfall extremes, it was found that regional variation in the mean annual precipitation could explain a significant part of the spatial variability. Still, this variable was found to be of minor influence in comparison to explanatory variables in the temporal domain. The identified significant temporal variables comprise the East Atlantic pattern, the average summer precipitation, and the average summer temperature. The two latter showed a high relative importance. The established link will be beneficial when predicting future occurrences of precipitation extremes. © 2013. American Geophysical Union. All Rights Reserved. Source

Zydelis R.,DHI | Small C.,BirdLife International Global Seabird Programme | French G.,BirdLife International Global Seabird Programme
Biological Conservation | Year: 2013

Based on bird feeding ecology we identified 148 seabird species as susceptible to bycatch in gillnets, of which 81 have been recorded caught. The highest densities of susceptible species occur in temperate and sub-polar regions of both hemispheres, with lower densities in tropical regions. Gillnet fisheries are widespread and particularly prevalent in coastal areas. A review of reported bycatch estimates suggests that at least 400,000 birds die in gillnets each year. The highest bycatch has been reported in the Northwest Pacific, Iceland and the Baltic Sea. Species suffering potentially significant impacts of gillnet mortality include common guillemot (Uria aalge), thick-billed guillemot ( Uria lomvia), red-throated loon ( Gavia stellata), Humboldt penguin (Spheniscus humboldti), Magellanic penguin ( Spheniscus magellanicus), yellow-eyed penguin (Megadyptes antipodes), little penguin (Eudyptula minor), greater scaup (Aythya marila) and long-tailed duck (Clangula hyemalis). Although reports of seabird bycatch in gillnets are relatively numerous, the magnitude of this phenomenon is poorly known for all regions. Further, population modelling to assess effects of gillnet bycatch mortality on seabird populations has rarely been feasible and there is a need for further data to advance development of bycatch mitigation measures. © 2013 Elsevier Ltd. Source

Nielsen J.E.,University of Aalborg | Jensen N.E.,DHI | Rasmussen M.R.,University of Aalborg
Atmospheric Research | Year: 2013

Estimation of the radar reflectivity from Local Area Weather Radars (LAWR) is investigated. Normally, the LAWR system operates with the Dimensionless Radar Output (DRO) instead of dBZ, because the absolute scaling to dBZ is unknown for the LAWR. A transformation methodology is proposed for LAWR DRO-dBZ conversion. The method applies dBZ observations from ground based disdrometers. The paper illustrates the possibility of establishing a direct relationship between the LAWR DRO estimates and the physical radar reflectivity of the precipitation. Also, rain intensity estimate from the LAWR system, by means of the Marshall-Palmer relation, is conducted nonlinearly from the DRO estimate. This diverges from prior investigations and applications of the LAWR system, which typically rely on a linear assumption between the rain intensity and the LAWR DRO. © 2012 Elsevier B.V. Source

Arnbjerg-Nielsen K.,Technical University of Denmark | Madsen H.,DHI
Climate Research | Year: 2015

Climate change adaptation studies on urban flooding are often based on a model chain approach from climate forcing scenarios to analysis of adaptation measures. Previous analyses of climate change impacts in Copenhagen, Denmark, were supplemented by 2 high-end scenario simulations. These include a regional climate model projection forced to a global temperature increase of 6°C in 2100 as well as a projection based on a high radiative forcing scenario (RCP8.5). With these scenarios, projected impacts of extreme precipitation increase significantly. For extreme sea surges, the impacts do not seem to change substantially compared to currently applied projections. The flood risk (in terms of expected annual damage, EAD) from sea surge is likely to increase by more than 2 orders of magnitude in 2100 compared to the present cost. The risk from pluvial flooding in 2000 is likely to increase by almost 4 and 8 times the current EAD for the RCP8.5 and 6°C scenario, respectively. For both hazards, business-as-usual is not a possible scenario, since even in the absence of policy-driven changes, significant autonomous adaptation is likely to occur. Copenhagen has developed an adaptation plan to pluvial flooding that makes the urban areas more robust and reduces the risk of flooding under the current climate to a very low level. The reduction in flood risk for the A1B scenario is substantial (corresponding to 0.2-0.3 times the current EAD in 2100), and even in the high-end scenarios, the risk is significantly reduced (corresponding to 0.6-1.0 and 1.2-2.1 times the current EAD for the RCP8.5 and 6°C scenario, respectively). © The authors 2015. Source

Agency: Cordis | Branch: H2020 | Program: RIA | Phase: SFS-11b-2015 | Award Amount: 6.92M | Year: 2016

Aquaculture is one of five sectors in the EUs Blue Growth Strategy, aimed at harnessing untapped potential for food production and jobs whilst focusing on environmental sustainability. TAPAS addresses this challenge by supporting member states to establish a coherent and efficient regulatory framework aimed at sustainable growth. TAPAS will use a requirements analysis to evaluate existing regulatory and licensing frameworks across the EU, taking account of the range of production environments and specificities and emerging approaches such as offshore technologies, integrated multi-trophic aquaculture, and integration with other sectors. We will propose new, flexible approaches to open methods of coordination, working to unified, common standards. TAPAS will also evaluate existing tools for economic assessment of aquaculture sustainability affecting sectoral growth. TAPAS will critically evaluate the capabilities and verification level of existing ecosystem planning tools and will develop new approaches for evaluation of carrying capacities, environmental impact and future risk. TAPAS will improve existing and develop new models for far- and near-field environmental assessment providing better monitoring, observation, forecasting and early warning technologies. The innovative methodologies and components emerging from TAPAS will be integrated in an Aquaculture Sustainability Toolbox complemented by a decision support system to support the development and implementation of coastal and marine spatial planning enabling less costly, more transparent and more efficient licensing. TAPAS partners will collaborate with key industry regulators and certifiers through case studies to ensure the acceptability and utility of project approach and outcomes. Training, dissemination and outreach activities will specifically target improvement of the image of European aquaculture and uptake of outputs by regulators, while promoting an integrated sustainable strategy for development.

Discover hidden collaborations