Development of flood mitigation strategies toward sustainable development

Natural Hazards - Decreasing flood damages in a basin and achieving sustainable development reveal the necessity of integrated management of flood. Integrated flood management requires the...     

System dynamics assessment of mitigation strategies for power distribution poles subjected to hurricanes

This paper presents a system dynamics-based method to evaluate the cost-effectiveness of mitigation strategies for the replacement of power distribution poles subjected to hurricanes. The method demonstrates how the performance of poles distributed over a certain region, as well as the cost of maintenance and replacement, varies with time. Compared to a static assessment, the dynamic analysis provides more information for decision-making about replacement strategies, e.g., the changing trend of cost and performance in a period, and thus a potential trade-off between short-term and long-term benefits. Also, some variables and features that play an important role in cost-effectiveness are examined using sensitivity analysis, so that refinement of pole replacement strategies can be made. The model depicts the systemic and dynamic natures of long-term cost-effectiveness of pole maintenance and assists in the development of a better replacement strategy for multipole systems. In a case study, the model was applied to a typical region subjected to hurricanes, i.e., Miami-Dade County in Florida, USA. The simulation results from the model led to a maintenance strategy optimization that included both selection of class of poles and ways of replacement.     

A method for na-tech risk assessment as supporting tool for land use planning mitigation strategies

Hazardous industrial sites have always represented a threat for the community often provoking major accidents overcoming the boundaries of the plants and affecting the surrounding urban areas. If the industrial sites are located in natural hazard-prone areas, technological accidents may be triggered by natural events, generating so-called na-tech events which may modify and increase the impact and the overall damage in the areas around them. Nevertheless, natural and technological hazards are still treated as two separate issues, and up to now the methods for na-tech risk assessment have been developed mainly for specific natural hazards, generally restricted to some plant typologies and to the area of the plant itself. Based on a review of the current na-tech literature, this article illustrates a risk assessment method as a supporting tool for land use planning strategies aimed at reducing na-tech risk in urban areas. More specifically, a multi attribute decision-making method, combined with fuzzy techniques, has been developed. The method allows planners to take into account, according to different territorial units, all the individual na-tech risk factors, measured through both quantitative and qualitative parameters, while providing them with a na-tech risk index, useful to rank the territorial units and to single out the priority intervention areas. The method is designed to process information generally available about hazardous plants (safety reports), natural hazards (hazard maps) and features of urban systems mainly influencing their exposure and vulnerability to na-tech events (common statistical territorial data). Furthermore, the method implemented into a GIS framework should easily provide planners with comparable maps to figure out the hazard factors and the main territorial features influencing the exposure and vulnerability of urban systems to na-tech events. The method has been tested on a middle-sized Municipality in the Campania Region, identified as 2nd class seismic zone, according to the Ordinance 3274/2003, in which a LPG storage plant, classified as a plant with major accident potential by the Seveso II Directive (art. 9), is located just within the city core.     

Human impacts on Laguna de Bay, Philippines and management strategies for their mitigation

Laguna de Bay is the largest lake in the Philippines bordering metropolitan Manila, the nation's capital and the industrial hub of the country. As a multiple-use resource the lake is of prime importance for its fisheries, as a transport route and as a water source for the cooling of industrial plants and for irrigation. The lake is also envisaged to supply the domestic water needs of the basin in the year 2000. With rapid urbanization, industrial development and deforestation of its watershed, Laguna de Bay has been stressed with sedimentation, overexploitation of its fisheries and pollution. Various management strategies have been adopted by government to address such human impacts. Among the major programs are the installation of a hydraulic control structure, implementation of a zoning and management plan and the formulation of a master plan. There is need for an integrated approach for the management of the Laguna de Bay basin for its sustainable development.     

Coastal erosion risk assessment to discuss mitigation strategies: Barra-Vagueira,Portugal

Natural Hazards - Worldwide coastal zones present serious erosion problems that cause loss of territory. This phenomenon exposes people and goods to the threat, being necessary to carry out a...     

Reaching the limits: a geographic approach for understanding food insecurity and household hunger mitigation strategies in Minneapolis-Saint Paul, USA

Research on hunger and food security in the Global South and the Global North has often emphasized different factors and scales of analyses. Unlike newer monitoring systems in the Global South, which evolved substantially following critiques by Amartya Sen, US food security research has rarely combined the two dimensions of food availability and food access. Furthermore, this research has paid scant attention to household coping strategies. This study responds to this lacuna in US hunger research by developing a spatial model for predicting risk to food insecurity based on proxy measures for access (three demographic variables) and availability (grocery store density). The study then employs qualitative methodologies (surveys and semi-structured interviews) to understand household coping strategies in two ethnically distinct areas in Minneapolis-Saint Paul at risk to food insecurity. One neighborhood is dominated by Southeast Asian and East African immigrants and the other by African-Americans. This approach should allow for better targeting of food aid and programs that help alleviate food insecurity.     

Rural organizational impacts,mitigation strategies,and resilience to the 2010 Darfield earthquake,New Zealand

A methodology for evaluating real-time optimal reservoir releases under flooding conditions that minimizes flood damages for a river-reservoir system is described in this paper. The problem is formulated as a discrete-time optimal control problem in which reservoir releases are the control variables, and water surface elevations and discharges are the state variables. Constraints imposed on the reservoir’s water surface elevations and reservoir releases to the downstream reaches are incorporated into an objective function using a penalty function method. The optimal control model consists of the two primary interfaced components: (1) the U.S. Geological Survey Full EQuation routing model to simulate the unsteady flow dynamics of the river-reservoir system and (2) an optimization technique, simulated annealing that optimizes reservoir releases (flood control gate operations) subject to system constraints. The model solves an augmented control problem. The model was applied to the river-reservoir system of Lake Travis on the Lower Colorado River in Texas. The model application to Lake Travis revealed the usefulness of the model in improving a given operation policy, regardless of the type objective function (linear or nonlinear). The methodology and the operation model developed here are unique since they can be applied to any river-reservoir system, do not require simplification of nonlinearities, and guarantee the determination of an optimal or near-global optima.     

Marketable risk permits for natural disaster mitigation

Building codes are important for natural disaster mitigation. Typical public policy approach to building safety is the command-and-control mechanism. Local government sets minimum standards that every new building must attain. Because a proposed change in the requirements is stated in terms of additional safety, the marginal cost would be different for each building. Those with high marginal cost are over-represented in the deliberations because for these buildings the cost is highly salient. Thus, many good proposals are defeated, and no buildings are made safer. The marketable risk permits approach uses a market mechanism to encourage efficient safety upgrade. The building code would have two levels of safety, the lower level corresponding to the status quo. Each new building would be endowed with a quantity of risk permits. Developers who construct to the lower code level must purchase additional risk permits. Developers who build to the higher code level could sell their risk permits. Thus, for the few buildings for which the higher code level is expensive, developers could avoid high costs by purchasing risk permits instead. Government policy would determine the endowment of risk permits, as a fraction of total risk-reduction potential of the higher code level. The market would determine the price of risk permits, as well as which buildings get constructed to the higher code level. Under a risk permit policy, the marginal cost of safety would be considerably less than under a command-control policy. In situations where corruption already operates as a mechanism for providing relief to developers with high costs, a risk permit policy has little effect on the number of bribes, but the interaction drives down the price of both bribes and risk permits.     

Measuring earthquake risk concentration for hazard mitigation

One of the biggest impacts of a disaster is the effect it can have on community and regional housing and the ability of people, communities and regions to recover from the damages. Policy decisions involving investments in loss reduction measures and response and recovery are best informed by the integration of scientific and socioeconomic information. Natural scientists develop hazard scenarios for stakeholders and emergency officials to assess the impacts of a particular disaster outcome. Social scientists have found that housing losses and recovery affect individuals in lower socioeconomic status disproportionately. By combining socioeconomic status data from the US Census with an earthquake scenario for southern California, an event-driven conditional distribution of earthquake risk is used to prioritize investment decisions for earthquake hazard mitigation. Simulation of the damages in the scenario showed a statistically significant risk concentration in census tracts with large numbers of residents of lower socioeconomic status living in multi-family housing and mobile homes. An application of the approach is demonstrated in Los Angeles County as a decision criterion in a building retrofit program. The earthquake scenario was used to evaluate the economic benefits of a program for voluntary mitigation and a combined program of voluntary mitigation and regulated mitigation based on socioeconomic status (mandate requiring mitigation in census tracts meeting specific damage and income thresholds). Although the analysis is a hypothetical scenario based on a simulation of a great earthquake, the results and potential outcomes show that a regulated program with a socioeconomic decision criterion would have significant benefits to vulnerable populations.     

灌溉诱发型滑坡风险控制关键技术

长期灌溉引起地下水位上升诱发滑坡发生是灌溉诱发型滑坡的基本特征,有效控制地下水位是灌溉诱发型滑坡风险管理的根本措施.通过灌溉量控制、竖向混合孔疏排水、水平疏排水3种排水措施,可以实现灌溉诱发型滑坡的风险控制.采用数值模拟的手段,计算了不同灌溉量下地下水动力场及其对应的台塬斜坡稳定性,模拟了不同布井方式下的竖向混合井疏排地下水的效果,结果表明,灌溉量控制在350×10 4m3/a以下可实现滑坡风险控制,竖向混合排水井间距为40m时可提高单体斜坡的稳定性.统筹考虑各种因素,提出了以控制灌溉量为主,辅以竖向混合孔排水和水平排水的黑方台灌区滑坡的风险控制措施.     

Environmental degradation in the Hexi Corridor region of China over the last 50 years and comprehensive mitigation and rehabilitation strategies

The regional hydrology and ecosystems of the Hexi Corridor region of northwestern China have changed over the last half century under the driving force of intense human activity and regional climate changes. Streamflow issuing from mountains in the eastern section of the Corridor by way of the Shiyang River has decreased significantly. Annual mountain outflow from the Heihe and Shule Rivers in the central and western portions of the Corridor, respectively, have tended to increase; however, their downstream discharge has decreased sharply. These lower reaches clearly display anthropogenic hydrological features. Water salinization and pollution have worsened. Presently, up to 208 km of river courses exhibit the poorest water pollution grades of IV and V. Overall, the forested area in the south Qilian Mountain region has decreased by 16.5% in the last 50 years, but has recently begun to show a gradual increase. However, natural desert forests in the northern portion of the Hexi Corridor have continued in a trend of degradation and rapid disappearance, with 3431 km² lost in Minqin and Ejin counties alone. Grasslands have been progressively degraded and their area decreased such that grasslands in the Hexi Corridor region only cover 46.86% of their former area. Desertification has been exacerbated and the grasslands' stock capacity reduced. In the Hexi Corridor region desertification has proceeded swiftly over the last 50 years, reaching, in the early 1980s, a maximum annual rate of 2.15% of total initial grassland area. However, from the late 1980s through the 1990s their desertification rate has dropped significantly. A unified watershed-scale plan for water use and management in different regions of the Hexi Corridor, considering water demands for economic development as well as ecosystem maintenance and remediation, must be implemented. The improved and ultimate sustainability of regional development for the Hexi Corridor is linked to following ecological criteria in exploiting land resources, and to systematically protect ecosystem function, allowing for sound ecosystem development.     

Tracking volcanic sulfur dioxide clouds for aviation hazard mitigation

Satellite measurements of volcanic sulfur dioxide (SO₂) emissions can provide critical information for aviation hazard mitigation, particularly when ash detection techniques fail. Recent developments in space-based SO₂ monitoring are discussed, focusing on daily, global ultraviolet (UV) measurements by the Ozone Monitoring Instrument (OMI) on NASA’s Aura satellite. OMI’s high sensitivity to SO₂ permits long-range tracking of volcanic clouds in the upper troposphere and lower stratosphere (UTLS) and accurate mapping of their perimeters to facilitate avoidance. Examples from 2006 to 2007 include eruptions of Soufriere Hills (Montserrat), Rabaul (Papua New Guinea), Nyamuragira (DR Congo), and Jebel at Tair (Yemen). A tendency for some volcanic clouds to occupy the jet stream suggests an increased threat to aircraft that exploit this phenomenon. Synergy between NASA A-Train sensors such as OMI and the Atmospheric Infrared Sounder (AIRS) on the Aqua satellite can provide critical information on volcanic cloud altitude. OMI and AIRS SO₂ data products are being produced in near real-time for distribution to Volcanic Ash Advisory Centers (VAACs) via a NOAA website. Operational issues arising from these improved SO₂ measurements include the reliability of SO₂ as proxy for co-erupted ash, the duration of VAAC advisories for long-lived volcanic clouds, and the potential effects of elevated concentrations of SO₂ and sulfate aerosol in ash-poor clouds on aircraft and avionics (including cumulative effects after multiple inadvertent transits through dilute clouds). Further research is required in these areas. Aviation community assistance is sought through continued reporting of sulfurous odors or other indications of diffuse volcanic cloud encounters, in order to validate the satellite retrievals.     

Reaction-driven casing expansion: potential for wellbore leakage mitigation

It is generally challenging to predict the post-abandonment behaviour and integrity of wellbores. Leakage is, moreover, difficult to mitigate, particularly between the steel casing and outer cement sheath. Radially expanding the casing with some form of internal plug, thereby closing annular voids and fractures around it, offers a possible solution to both issues. However, such expansion requires development of substantial internal stresses. Chemical reactions that involve a solid volume increase and produce a force of crystallisation (FoC), such as CaO hydration, offer obvious potential. However, while thermodynamically capable of producing stresses in the GPa range, the maximum stress obtainable by CaO hydration has not been validated or determined experimentally. Here, we report uniaxial compaction/expansion experiments performed in an oedometer-type apparatus on precompacted CaO powder, at 65 °C and at atmospheric pore fluid pressure. Using this set-up, the FoC generated during CaO hydration could be measured directly. Our results show FoC-induced stresses reaching up to 153 MPa, with reaction stopping or slowing down before completion. Failure to achieve the GPa stresses predicted by theory is attributed to competition between FoC development and its inhibiting effect on reaction progress. Microstructural observations indicate that reaction-induced stresses shut down pathways for water into the sample, hampering ongoing reaction and limiting the magnitude of stress build-up to the values observed. The results nonetheless point the way to understanding the behaviour of such systems and to finding engineering solutions that may allow large controlled stresses and strains to be achieved in wellbore sealing operations in future.     

山区道路泥石流减灾问题与对策

文章通过分析我国山区道路泥石流防治的特点与需求,认为山区道路潜在泥石流的判识与预测、泥石流对线路展布的制约、泥石流对道路工程设计的影响等是山区道路建设的关键技术问题。在山区建设中应研究潜在泥石流的判识方法、发展山区道路选线理论、认识道路工程与环境相互作用机制、创建与环境协调的道路工程反馈设计理论、构建山区道路泥石流减灾技术体系、开发道路环境灾害信息系统等工作。系统分析了道路勘察选线、个体工程设计、施工、运营阶段应注意的泥石流防治问题,根据不同阶段的灾害危害方式与特征,提出道路建设不同阶段的泥石流防治对策。     

地质灾害预警工程体系探讨

本文概述了地质灾害预警工程提出的背景、基本概念、预警工作目标和工作阶段划分。作者把地质灾害预警工程分为空间预警工程和时间预警工程,介绍了相应的一些简单实例。提出了地质灾害预警工程的技术工作体系的组织工作体系,特别强调了在政论机构统一组织下,发挥专业技术人员的作用和积极调动广大群众参与具有同等的重要性。     

A multi-agent-based model for sustainable governance of urban flood risk mitigation measures

Natural Hazards - Consequences of urban floods increased and diversified in terms of social, economical and environmental effects, due to the dense and unplanned urbanization in areas at risk of...     

泥石流灾害的物源控制与高性能减灾

传统的观点认为山区泥石流灾害的形成主要取决于降水,其产汇流运动的过程是可采用水文过程模拟的物理过程。基于目前泥石流灾害集中分布于地震带和干旱河谷的现象以及现有的泥石流形成与防治研究基础,我们发现在人类居住与活动的山区,其坡度和降水极易满足泥石流灾害的形成条件,因此物源控制着泥石流灾害的孕育、形成和演化,主宰了灾害性泥石流的过程。物源的动态变化改变了泥石流发育的难易程度,主导了泥石流的规模和频率变化。泥石流物源在内外动力作用下经历松散化或密实化两个不同的演化过程,不同密度的土体通过剪缩或剪胀形成不同规模、频率与性质的泥石流。此外物源也控制了泥石流的规模放大过程。实践证明基于物源控制理论的区域预测、分级多指标预警和工程调控技术是科学有效的。因此,灾害性泥石流是一个地质作用主导的地质过程,该过程的特征描述需要更多地考虑基于地质环境条件的经验模型,且高效能的灾害预测预警与调控需要基于物源控制的机理和过程而进行。