Integrating a multivariate extreme value method within a system flood risk analysis model

Effective management of flooding requires models that are capable of quantifying flood risk. Quantification of flood risk involves both the quantification of probabilities of flooding and the associated consequences. Modern flood risk models account for the probabilities of extreme hydraulic loading events and also include a probabilistic representation of the performance of flood defence infrastructure and its associated reliability. The spatial and temporal variability of flood events makes probabilistic representation of the hydraulic loading conditions on the flood defences complex. In the system method used widely within England and Wales, simplifying assumptions relating to the spatial dependence of flood events are made. Recent research has shown the benefits of using improved multivariate extreme value methods to define the hydraulic loading conditions for flood risk analysis models. This paper describes the development of an improved modelling system that enhances the systems-based risk analysis model currently applied in practice, through the incorporation of a multivariate extreme value model. The improved system has been presented on a case study site in the North West of England

A generic and practical wave overtopping model that includes uncertainty

Mean wave overtopping discharge is generally accepted to be a primary design criterion for assessing the performance of coastal structures. It is a boundary condition for many coastal flood risk assessments. Modern methods for assessing wave overtopping discharges and their consequences are well documented and reported. Among the various tools available for assessing wave overtopping, the use of artificial neural networks has become increasingly popular. This paper introduces the next stage in the development of these models. Using the same source data, the new generic meta-modelling overtopping model reduces uncertainties and gives clear guidance on the range and validity of the outputs

Gravel beach profile response allowing for bimodal sea-states

The south coast of the UK is identified as a location where significant wave swell components are present within the regional wave climate. During the winters of 2006 and 2014, several sites along the south coast of the UK were subject to significant damages where flood events were recorded. These sea–states were characterised by having a double–peaked wave spectra, observing a connection between wave spectrum shape and beach response. A 2D physical model study was carried out to investigate the effect of gravel beach profile response under wave spectra characterised by swell and wind wave periods in various combinations. The physical model results have shown the effect of bimodal wave spectrum on the beach crest erosion and have been compared with the parametric model of SHINGLE and the numerical model XBeach-G. Based on this 2D physical model study a new parametric model, Shingle–B, has been derived and an online tool has been developed and made available on the website for the National Network of Regional Coastal Monitoring Programmes of England. This new tool has been validated with two sites in the South of England where field data of both waves and profiles was available

Preoperative and perioperative use of levosimendan in cardiac surgery: European expert opinion

In cardiac surgery, postoperative low cardiac output has been shown to correlate with increased rates of organ failure and mortality. Catecholamines have been the standard therapy for many years, although they carry substantial risk for adverse cardiac and systemic effects, and have been reported to be associated with increased mortality. On the other hand, the calcium sensitiser and potassium channel opener levosimendan has been shown to improve cardiac function with no imbalance in oxygen consumption, and to have protective effects in other organs. Numerous clinical trials have indicated favourable cardiac and non-cardiac effects of preoperative and perioperative administration of levosimendan. A panel of 27 experts from 18 countries has now reviewed the literature on the use of levosimendan in on-pump and off-pump coronary artery bypass grafting and in heart valve surgery. This panel discussed the published evidence in these various settings, and agreed to vote on a set of questions related to the cardioprotective effects of levosimendan when administered preoperatively, with the purpose of reaching a consensus on which patients could benefit from the preoperative use of levosimendan and in which kind of procedures, and at which doses and timing should levosimendan be administered. Here, we present a systematic review of the literature to report on the completed and ongoing studies on levosimendan, including the newly commenced LEVO-CTS phase III study (NCT02025621), and on the consensus reached on the recommendations proposed for the use of preoperative levosimendan