200 research outputs found

    Placement, porosity and randomness of cube and Cubipod armor layers

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    Although little attention is usually given to the armor porosity and armor randomness of randomly placed concrete armor units in mound breakwaters, significant model effects may occur if armor porosity and randomness are different for prototype and small-scale models. Armor randomness and porosity are easier to control in small-scale models because they are generally constructed by hand in dry and perfect viewing conditions; equipment and environmental constraints make control at prototype scale more difficult. Results from three-dimensional small-scale placement tests are analyzed when cube and Cubipod units are placed with a small-scale crawler crane and pressure clamps. Armor porosity was not workable below 37% for cubes and 35% for Cubipods; placement grids were obtained for feasible armor porosities, considering row settlements during construction as well. Amethodology to measure armor randomness using high-precision laser scanning, similar to terrestrial LIDAR, was tested with small-scale cube and Cubipod armor. Three armor randomness indexes (ARIs) measured the randomness of cube and Cubipod armor; the values for ARIs were higher for Cubipod armor than for cube armor. (C) 2014 American Society of Civil EngineersThe authors would like to acknowledge the financial support received from the CDTI (CUBIPOD and CLIOMAR Projects), SATO-OHL Group (CLIOMAR Project), and the Spanish Ministry of Economy and Competitiveness (Grant BIA2012-33967). The third author was financially supported through the FPU program (Formacion del Profesorado Universitario) funded by the Spanish Ministry of Education (Ministerio de Educacion, Cultura y Deporte). The authors thank Tomas J. Perez for assisting with the 3D placement tests and processing the laser-scanner data, and Debra Westall for revising the manuscript.Pardo De Gregorio, V.; Herrera Gamboa, MP.; Molines Llodra, J.; Medina Folgado, JR. (2014). Placement, porosity and randomness of cube and Cubipod armor layers. Journal of Waterway, Port, Coastal, and Ocean Engineering. 140(5). doi:10.1061/(ASCE)WW.1943-5460.0000245S140

    DESIGNING PORT INFRASTRUCTURE FOR SEA LEVEL CHANGE: A SURVEY OF U.S. ENGINEERS

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    Seaports are particularly vulnerable to the impacts of climate change due to their coastal location. With the potential threat of up to 2.5m in sea level rise by 2100, resilient port infrastructure is vital for the continued operation of ports. There are strong economic and social incentives for seaports to provide long-term resilience against climate conditions. For example, service disruptions can cost billions of dollars and impact the livelihoods of those who depend on the port. Engineers play a pivotal role in improving the resilience of ports, as they are responsible for designing port infrastructure that will be adequately prepared for future sea level change (SLC). However, incorporating SLC is a challenging task due to the uncertainty of SLC projections, the long service lives of port infrastructure, and the differing guidelines and recommendations for managing SLC. Through an online survey of 85 U.S. port and marine infrastructure engineers, this research explores the engineering community’s attitude and approach to planning for SLC for large-scale maritime infrastructure projects. Survey findings highlight the extent that projects incorporate SLC, the wide range of factors that drive the inclusion of SLC, and the numerous barriers that prevent engineers from incorporating SLC into design. This research emphasizes that traditional engineering practices may no longer be appropriate for dealing with climate change design variables and their associated uncertainties. Furthermore, results call for collaboration among engineers, port authorities, and policy makers to develop design standards and practical design methods for designing resilient port infrastructure

    Integrating hydrological modelling and ecosystem functioning for environmental flows in climate change scenarios in the Zambezi River (Zambezi Region, Namibia)

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    The Zambezi-Chobe wetlands in Namibia are of great international importance for trans-boundary water management because of their remarkable ecological characteristics and the variety and magnitude of the ecosystem services provided. The main objective of this study is to establish the hydro-ecological baseline for the application of environmental flow regimes (EFR). The specific objectives are: (i) the assessment of environmental flow components (EFC) in the current near-natural hydrological conditions; (ii) the generation of future scenarios for climatic and socioeconomic changes; (iii) the estimation of the area duration curves and estimated annual habitat during the inundation of the critical habitats for fisheries (mulapos), under the existing conditions and future scenarios; and (iv) to provide a framework for the future application of EFRs, based on hydrological and ecological processes. To make a sound analysis of the ecological implications, first we develop a conceptual framework of the linkages between the hydrological and biological processes concerning fish communities, because of the critical role of fisheries in the region. The EFCs in near-natural hydrological conditions provide the basis for developing interim EFRs in the region, within the framework of an adaptive management of water resources. The future scenarios indicate a mitigation of the flow variability; and, in the worst-case scenario, the reduction of the maximum flow and inundated area of the mulapos would result in a reduction of the estimated annual habitat of 22%. This means a reduction in the spawning habitats for quiet-water species, in the food resources for fry and juvenile fish and a consequent reduction in fish stocks. Furthermore, the habitat loss during low events is similar and greater under both scenarios, at ca. 35%. Here we corroborate that the EFCs and their variability may become the building blocks of flow-ecology models that lead to environmental flow recommendations, monitoring and research programmes and flow protection activities.This research was part of the research project CERPA (Certification of Protected Areas), funded by the German Federal Ministry of Education and Research (BMBF), and focused on the evaluation of new market-based instruments for biodiversity conservation and their socioeconomic implications. The authors also thank two anonymous reviewers who provided substantial input that improved the manuscript. The study has been partially funded by the national research project IMPADAPT (CGL2013-48424-C2-1-R), with MINECO (Spanish Ministry of Economy) and FEDER funds.Martinez-Capel, F.; García López, L.; Beyer, M. (2017). Integrating hydrological modelling and ecosystem functioning for environmental flows in climate change scenarios in the Zambezi River (Zambezi Region, Namibia). River Research and Applications. 33(2):258-275. https://doi.org/10.1002/rra.3058S25827533

    The Role of Trust in Public Attitudes toward Invasive Species Management on Guam: A Case Study

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    Public attitudes toward invasive alien species management and trust in managers’ ability to effectively manage non-native species can determine public support for conservation action. Guam has experienced widespread species loss and ecosystem transformation due to invasive species. Despite Guam’s long history with invasives and efforts to eradicate them, we know little about the sociological context of invasive species. Using focused group discussions, we explore public attitudes toward invasive species management. Respondents expressed support for management activities and a desire to participate directly in conservation actions. Participants also expressed frustration with government institutions and lack of confidence in managers’ abilities to control invasive species. Perceptions of managers’ trustworthiness, communication with managers, and positive personal experiences with managers were related to positive attitudes about management and support for existing initiatives
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