3533 results

  • Prevalence and environmental determinants of cutaneous leishmaniasis in rural communities in Tigray, northern Ethiopia

    Authors: Yohannes, M.; Abebe, Z.; Boelee, E. (2019)
    Published in: PLOS neglected tropicel diseases (2019), page 1-14

    Cutaneous leishmaniasis (CL) is a skin infection, transmitted by sandflies. It is most common in Ethiopia, but so far only a few hundred people have received treatment. Five rural villages in Tigray Region, in the north of Ethiopia, were visited to assess the status and determinants of CL. In a door-to-door survey 9,622 residents of 1,721 households were examined and interviewed. A total of 222 had active lesions, an average prevalence of 2.3% CL. Children (up to 9 years old) and teenagers (age 10–19) were more affected than other groups. Most active lesions were found in the face and on arms. Almost 11% of the households had one or more cases of CL and this was associated with proximity to habitats of hyrax, intermediate hosts of the disease. A total of 2009 people (20.9%) showed scars from earlier infections. The findings show how widespread the disease is in the north of Ethiopia and provide some first insights into the environmental factors that influence transmission.

  • Modelling the effect of kelp on sand dune erosion

    Authors: Rooijen, A. van; Winter, G. (2019)
    Published in: Future directions from 40°S and beyond : proceedings of the Australasian coasts and ports 2019 conference (Hobart, New Zealand, 10-13 September 2019) (2019), page 1-6

    Large parts of the Australian coastline are surrounded by nearshore aquatic vegetation, such as kelp or seagrass. Although it is widely accepted that vegetation plays an important role in dissipating wave energy and reducing current magnitudes, there is a limited understanding on how this affects coastal morphology. Consequently, most coastal models can currently not account for this effect. The aim of this work is to assess the effect of flexible aquatic vegetation, kelp in particular, on sand dune erosion using a process-based model, XBeach. The model is validated with experimental data obtained from literature, showing that XBeach can accurately model the measured wave evolution. Moreover, the model is able to reproduce dune erosion volume reasonably well. To investigate the effectiveness of kelp in mitigating storm-induced erosion, a series of synthetic storm events were simulated for a beach in northern Tasmania (Australia) that has suffered from erosion in the past. Model scenarios were focused on climate change effects, such as sea level rise and change in kelp forest cover. The results of this modelling study suggest that, across a range of climate change scenarios and storm intensities, the presence of kelp may have a significant effect on coastal stability during storm events.

  • Future directions from 40°S and beyond : proceedings of the Australasian coasts and ports 2019 conference (Hobart, New Zealand, 10-13 September 2019)

    Originally published in 2019

  • Conventional reinforcement as a potential prevention measure against piping

    Authors: Akrami, S.; Bezuijen, A. (2019)
    Published in: Proceedings of the 17th European Conference on Soil Mechanics and Foundation Engineering - ECSMGE 2019 : geotechnical engineering, foundation of the future (Reykjavik, Iceland, 1-6 September 2019) (2019), page 1-7

    Piping is one of the main failure mechanisms that can affect the safety of water-retaining structures. A phenomenon that can occur when a local disruption of water structure caused sand erosion and concentration of seepage flow at that location. This entails sufficient hydraulic gradient resulting in the formation of shallow pipes in the sand layer. There are number of methods to increase the factor of safety against piping. An effective technique is soil reinforcement. The soil reinforcement can be performed by the inclusion of elements (strips, bars, etc) within the mass of soil in a preferred direction. Geogrids can be used as a convenient reinforcement material for improving the behaviour of the soil because of the high tensile resistance and significant friction in the soil. This paper presents laboratory experiments that were performed on unreinforced and reinforced soil samples. Reinforcement was done using different types of geogrid in different layers of the soil sample to investigate the effect of this method and arrangement of the geogrid sheets on the critical hydraulic gradient and resistance against piping. Subsequently, the results demonstrate that reinforcement increased the critical hydraulic gradient up to 75% compared to the value in unreinforced soil. The amount of improvement of the critical gradient is dependent on the arrangement and type of the geogrid.

  • Exploring the ‘solution space’ is key : SOLUTIONS recommends an early‑stage assessment of options to protect and restore water quality against chemical pollution

    Authors: Posthuma, L.; Gils, J.A.G. van (2019)
    Published in: Environmental sciences Europe, volume 31 (2019), page 1-9

    Present evaluations of chemical pollution in European surface and groundwater bodies focus on problem description and chemical classification of water quality. Surprisingly, relatively low attention has been paid to solutions of chemical pollution problems when those are encountered. Based on evaluations of current practices and available approaches, we suggest that water quality protection, monitoring, assessment and management of chemical pollution can be improved by implementing an early-stage exploration of the ‘solution space’. This follows from the innovative paradigm of solution-focused risk assessment, which was developed to improve the utility of risk assessments. The ‘solution space’ is defined as the set of potential activities that can be considered to protect or restore the water quality against hazards posed by chemical pollution. When using the paradigm, upfront exploration of solution options and selecting options that would be feasible given the local pollution context would result in comparative risk assessment outcomes. The comparative outcomes are useful for selecting optimal measures against chemical pollution for management prioritization and planning. It is recommended to apply the solution-focused risk assessment paradigm to improve the chemical pollution information for river basin management planning. To operationalize this, the present paper describes a still-growing database and strategy to find and select technical abatement and/or non-technical solution options for chemical pollution of surface waters. The solutions database and strategy can be applied to help prevent and reduce water quality problems. Various case studies show that implementing these can be effective, and how solution scenarios can be evaluated for their efficacy by comparative exposure and effect assessment.

  • Prioritisation of water pollutants : the EU Project SOLUTIONS proposes a methodological framework for the integration of mixture risk assessments into prioritisation procedures under the European Water Framework Directive

    Authors: Faust, M.; Gils, J.A.G. van (2019)
    Published in: Environmental sciences Europe, volume 31 (2019), page 1-4

    Current prioritisation procedures under the EU Water Framework Directive (WFD) do not account for risks from chemical mixtures. SOLUTIONS proposes a multiple-lines-of-evidence approach to tackle the problem effectively. The approach merges all available evidence from co-exposure modelling, chemical monitoring, effect-based monitoring, and ecological monitoring. Full implementation of the proposed methodology requires changes in the legal text in adaptation to scientific progress.

  • A holistic approach is key to protect water quality and monitor, assess and manage chemical pollution of European surface waters

    Authors: Posthuma, L.; Munthe, J.; Gils, J.A.G. van; Altenburger, R.; Müller, C.; Slobodnik, J.; Brack, W. (2019)
    Published in: Environmental sciences Europe, volume 31 (2019), page 1-5

    Chemical pollution of surface waters is a societal concern around the globe. Key problems in current water quality protection, assessment and management are the narrow focus on a small fraction of the chemicals in commerce, concerns for increasingly diverse chemical emissions, and lack of effective diagnosis and management approaches. In reply, three key concepts to address these challenges were developed and tested. The approaches were developed in the context of the European Union Water Framework Directive, based on principles such as the DPSIR-causal framework (Drivers, Pressure, Status, Impact and Response) and the basic feature that water protection and management should be based on a water-system level approach. Collaborative actions of researchers and stakeholders resulted in: (1) an operationalization and implementation of the solution-focused risk assessment paradigm as proposed in 2009, to improve the utility of risk assessments, (2) the provision of a large set of tools and services to prevent, monitor, assess and manage complex mixture pollution problems, and (3) a strategy and a database on intervention options. These three elements were recognized as core elements to help protecting and improving water quality. Although the methods were developed in the context of water quality problems in Europe, the three elements can be applied globally in water quality protection and management.

  • Data-fusion in geotechnical applications

    Authors: Noordam, A.; Zuada Coelho, B.E.; Teixeira, A.M.; Venmans, A.A.M. (2019)
    Published in: Information Technology in Geo-Engineering : proceedings of the 3rd International Conference (ICITG) (Guimarães, Portugal, 29 September - 2 October 2019) (2019), page 365-375

    Multisensor data-fusion corresponds to the combination and analysis of data from different sources, to provide a more reliable and accurate response. Although in the recent years several developments have occurred in the field of multisensor data-fusion, this concept is hardly new. What has evolved in the past years is the emergence and proliferation of new sensors, data availability and the advances in processing techniques, which have made the real-time fusion of data increasingly possible. In this paper, InSar and Lidar height measurements are used in combination with geological scenarios and CPTs to discover areas along dike-infrastructure which are at risk for instability. It will be shown that data-fusion can be used on line infrastructure to identify geotechnical threats and their significance, in time and in space.

  • Towards a pile quality prediction for screw displacement piles using Bayesian Networks

    Authors: Teixeira, A.M.; Noordam, A.; Lange, D.A. de (2019)
    Published in: Information Technology in Geo-Engineering : proceedings of the 3rd International Conference (ICITG) (Guimarães, Portugal, 29 September - 2 October 2019) (2019), page 540-550

    For screw displacement piles, there is quite some machine data being gathered during the installation, such as torque, pull down and velocity. However, there is no systematic way to process these data and knowledge from the engineer and machinist, neither during nor after the installation stage. Aiming to optimize the installation process, a research project was set up jointly with the Dutch industry. The main focus has been to deliver a proof-of-concept of a Bayesian Network that provides an assessment of the installation of each installed pile. The approach had to make use of analysing measurement data during installation, including expert knowledge and interpretation, and other usually unexploited process parameters. In the end, we believe that including these in a decision support system may bring us closer to a robotized installation of piles.

  • Information Technology in Geo-Engineering : proceedings of the 3rd International Conference (ICITG) (Guimarães, Portugal, 29 September - 2 October 2019)

    Authors: Gomes Correia, A.; Tinoco, J.; Cortez, P.; Lamas, L. (2020)

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