Modelling tropical cyclone risks for present and future climate change scenarios using geospatial techniques

Tropical cyclones and their devastating impacts are of great concern to coastal communities globally. An appropriate approach integrating climate change scenarios at local scales is essential for producing detailed risk models to support cyclone mitigation measures. This study developed a simple cyclone risk-modelling approach under present and future climate change scenarios using geospatial techniques at local scales, and tested using a case study in Sarankhola Upazila from coastal Bangladesh. Linear storm-surge models were developed up to 100-year return periods. A local sea level rise scenario of 0.34?m for the year 2050 was integrated with surge models to assess the climate change impact. The resultant storm-surge models were used in the risk-modelling procedures. The developed risk models successfully identified the spatial extent and levels of risk that match with actual extent and levels within an acceptable limit of deviation. The result showed that cyclone risk areas increased with the increase of return period. The study also revealed that climate change scenario intensified the cyclone risk area by 5–10% in every return period. The findings indicate this approach has the potential to model cyclone risk in other similar coastal environments for developing mitigation plans and strategies.     

节理分布空间变异的地下洞室稳定性概率分析

以岩土材料力学参数空间变异性的"点估计-有限元"分析方法为基础,结合节理分析时自身存在几何模型、网格划分等特性,扩展了该方法在节理分布空间变异性分析方面的适用性,明确了具体的研究步骤与方法。以某抽水蓄能水电站为例,通过分析节理空间变异性对围岩变形与塑性区的影响,验证了扩展后该方法的准确性和合理性。对工程案例开挖揭露的1400余条节理进行概率统计,建立了节理空间变异性的有限元分析模型;采用扩展后的概率分析方法,研究了节理分布对地下洞室群围岩开挖稳定性的影响。研究结果表明:(1)对比概率分析得到的围岩变形概率分布与现场监测结果,发现剔除变形异常点后监测变形量值大部分位于得到的位移概率分布范围内,说明节理的空间变异性是导致监测变形波动的主要影响因素;(2)围岩变形概率分布的标准差能有效识别出围岩开挖变形受节理空间变异性的影响程度,对于所给出的案例依次为:机窝>边墙>顶拱;(3)围岩塑性区的概率分区能合理判断地下洞室群开挖时受节理影响较大的区域和范围,为工程施工的支护设计提供依据。     

甘肃地质灾害风险管理思考

本文从5个方面分析了甘肃省地质灾害风险管控面临的形势,在此基础上提出了重构包括生命至上、天人合一、主动而为、依法防灾等地质灾害风险管理科学理念,提出了地质灾害风险管理应遵循资源整合与系统设计、预防优先与抗救结合、分级防治与风险共担、工程治理与避险并重、政府主导与社会参与、应急处置与长效防范6项原则,提出了今后甘肃地质灾害风险管控应从发挥制度在地质灾害风险管控引领作用、打造积极的防灾减灾文化、推进地质灾害防治全民能力提高、强化地质灾害风险管控科技支撑、构建地质灾害隐患动态风险评估体系、加强空天地一体化专群结合监测预警网络建设、加大地质灾害综合治理力度、扩大避险搬迁覆盖面和实施力度、地质灾害防治纳入国土风险管控体系等8个方面的着力点。     

泰青威天然气管道临朐段水毁灾害分布特征与风险评价

对泰青威天然气管道临朐段地质灾害发育特征进行调查研究发现,临朐段地质灾害类型主要为水毁灾害,具体可分为坡面水毁、河沟道水毁和台田地水毁。野外地质灾害实地调查临朐段管道沿线共发现地质灾害15处,其中坡面水毁点6处,河沟道水毁点4处,台田地水毁点5处。采用定性与半定量相结合的评价方法对其进行地质灾害风险评价,结果表明: 地质灾害风险等级较高的有1处,占6.66%; 风险等级中等的有4处,占26.67%; 风险等级较低的有10处,占66.67%。根据管道沿线地形地貌、地质灾害发育密度、风险等级等因素,划分地质灾害中易发区61 km,低易发区10 km,管道沿线以地质灾害中易发区为主。最后,针对不同类型、不同风险等级地质灾害提出了相应的防治消减措施,为后期管道安全运营和风险整治决策提供了有效的技术依据。     

海南岛天然橡胶林台风灾害风险评价

台风灾害是海南橡胶种植中影响最为严重和主要的灾害,为对其风险进行定量评估,本研究以海南岛天然橡胶林为研究对象,基于灾害风险评估理论,融合橡胶台风灾害、社会经济和气象数据,建立橡胶台风灾害危险性、暴露性和脆弱性评价模型,利用加权综合评价法开展天然橡胶林台风灾害风险评价。结果表明：海南橡胶种植高风险区位于沿海台风发生频繁市县,其中琼海、文昌、海口为海南岛橡胶灾害风险最高的地区,其次陵水、万宁、琼中、屯昌、东方等地区灾害风险也较高。风险最低地区位于中部五指山、保亭、乐东、三亚等地区,评价结果与实际灾害发生以及种植情况相符。评价结果表明,台风灾害危险性是风险的主导因子,但非单一决定因子,种植技术、品种改良等措施对脆弱性降低起到了较好的促进作用。评价结果可为橡胶林避灾防灾及种植布局提供依据。     

The relative influence of climate and housing development on current and projected future fire patterns and structure loss across three California landscapes

Climate and land use patterns are expected to change dramatically in the coming century, raising concern about their effects on wildfire patterns and subsequent impacts to human communities. The relative influence of climate versus land use on fires and their impacts, however, remains unclear, particularly given the substantial geographical variability in fire-prone places like California. We developed a modeling framework to compare the importance of climatic and human variables for explaining fire patterns and structure loss for three diverse California landscapes, then projected future large fire and structure loss probability under two different climate (hot-dry or warm-wet) and two different land use (rural or urban residential growth) scenarios. The relative importance of climate and housing pattern varied across regions and according to fire size or whether the model was for large fires or structure loss. The differing strengths of these relationships, in addition to differences in the nature and magnitude of projected climate or land use change, dictated the extent to which large fires or structure loss were projected to change in the future. Despite this variability, housing and human infrastructure were consistently more responsible for explaining fire ignitions and structure loss probability, whereas climate, topography, and fuel variables were more important for explaining large fire patterns. For all study areas, most structure loss occurred in areas with low housing density (from 0.08 to 2.01 units/ha), and expansion of rural residential land use increased structure loss probability in the future. Regardless of future climate scenario, large fire probability was only projected to increase in the northern and interior parts of the state, whereas climate change had no projected impact on fire probability in southern California. Given the variation in fire-climate relationships and land use effects, policy and management decision-making should be customized for specific geographical regions.     

Flood insurance arrangements in the European Union for future flood risk under climate and socioeconomic change

Flood risk will increase in many areas around the world due to climate change and increase in economic exposure. This implies that adequate flood insurance schemes are needed to adapt to increasing flood risk and to minimise welfare losses for households in flood-prone areas. Flood insurance markets may need reform to offer sufficient and affordable financial protection and incentives for risk reduction. Here, we present the results of a study that aims to evaluate the ability of flood insurance arrangements in Europe to cope with trends in flood risk, using criteria that encompass common elements of the policy debate on flood insurance reform. We show that the average risk-based flood insurance premium could double between 2015 and 2055 in the absence of more risk reduction by households exposed to flooding. We show that part of the expected future increase in flood risk could be limited by flood insurance mechanisms that better incentivise risk reduction by policyholders, which lowers vulnerability. The affordability of flood insurance can be improved by introducing the key features of public-private partnerships (PPPs), which include public reinsurance, limited premium cross-subsidisation between low- and high-risk households, and incentives for policyholder-level risk reduction. These findings were evaluated in a comprehensive sensitivity analysis and support ongoing reforms in Europe and abroad that move towards risk-based premiums and link insurance with risk reduction, strengthen purchase requirements, and engage in multi-stakeholder partnerships.     

动机、成本、风险：家长视角下研学旅游产品价值感知研究

以中小学生自然教育研学旅游作为具体情境,基于539份家长问卷数据阐释研学旅游动机与价值感知之间的关系,并通过成本感知和风险感知探讨其内在机制和边界条件。结果表明,家长感知的研学旅游动机越强烈,越容易感知到研学旅游产品所传递的价值,验证了研学旅游情境下动机对价值感知的积极影响,也形成了对动机与价值之间关系研究的理论补充。并且,这一动机除了直接作用于价值感知外,还会通过成本感知的部分中介作用影响价值感知,揭示了中国家长对于教育价值的重视会削弱其对“利失”的感知。此外,进一步验证了风险感知的积极影响,即家长感知研学旅游的不确定性水平越高,动机对价值感知的积极影响越明显,且会抑制成本感知对价值感知的负向作用,但风险感知水平达到一定高度时,其对成本感知与价值感知间的抑制作用将不显著。因此,面向需求设计打造产品,突出产品价值、加大宣传营销力度、把控活动安全、合理制定价格,获取家长群体的认同接受,将是研学旅游进一步拓展市场的重要考量。     

层次分析法在下垫面因子影响沙尘暴危险度研究中的应用

沙尘暴是一种危害严重的气象灾害,其形成依赖于大气环流和沙质地表两种不同密度的物理介质的相互作用,风力条件和下垫面的性质是影响沙尘暴强度和危害程度的两个重要因素。减轻沙尘暴危害的有效方法就是改善沙尘暴源地的下垫面状况,但这需要评估下垫面各因子在不同天气、气候背景条件下对沙尘暴发生的影响程度。从下垫面的角度出发,以内蒙古中西部地区为例,利用气象资料和实测数据,应用AHP方法对下垫面定性与定量因子进行综合分析,得出不同地区下垫面因子对沙尘暴发生作用的权重,为从下垫面角度研究沙尘暴危险度奠定基础。     

A probabilistic methodology to estimate future coastal flood risk due to sea level rise

In this paper we present a methodology to estimate the probability of future coastal flooding given uncertainty over possible sea level rise. We take as an example the range of sea level rise magnitudes for 2100 contained in the IPCC Third Assessment Report [Church, J.A., Gregory, J.M., Huybrechts, P., Kuhn, M., Lambeck, K., Nhuan, M.T., Qin, D., Woodworth, P.L., Anisimov, O.A., Bryan, F.O., Cazenave, A., Dixon, K.W., Fitzharris, B.B., Flato, G.M., Ganopolski, A., Gornitz, V., Lowe, J.A., Noda, A., Oberhuber, J.M., O'Farrell, S.P., Ohmura, A., Oppenheimer, M., Peltier, W.R., Raper, S.C.B., Ritz, C., Russell, G.L., Schlosser, E., Shum, C.K., Stocker, T.F., Stouffer, R.J., van de Wal, R.S.W., Voss, R., Wiebe, E.C., Wild, M., Wingham, D.J. and Zwally, H.J., 2001. Changes in sea level. In Houghton, J.T. et al. (eds), Climate Change 2001: The Scientific Basis. Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, United Kingdom, 881pp.] and infer a plausible probability distribution for this range. We then use a Monte Carlo procedure to sample from this distribution and use the resulting values as an additional boundary forcing for a two-dimensional model of coastal inundation used to simulate a 1 in 200 year extreme water level event. This yields an ensemble of simulations for an event of this magnitude occurring in 2100, where each member represents a different possible scenario of sea level rise by this time. We then develop a methodology to approximate the probability of flooding in each model grid cell over the ensemble and by combining these hazards maps with maps of land use values (consequence) we are able to estimate spatial contributions to flood risk that can aid planning and investment decisions. The method is then applied to a 32 km section of the UK coast in Somerset, South-West England and used to estimate the monetary losses and risk due a 1 in 200 year recurrence interval event under: (a) current conditions; (b) with the IPCC's most plausible value for sea level rise by 2100 (0.48 m) and (c) using the above methodology to fully account for uncertainty over possible sea level rise. The analysis shows that undertaking a risk assessment using the most plausible sea level rise value may significantly underestimate monetary losses as it fails to account for the impact of low probability, high consequence events. The developed method provides an objective basis for decisions regarding future defence spending and can be easily extended to consider other sources of uncertainty such as changing event frequency–magnitude distribution, changing storm surge conditions or model structural uncertainty, either singly or in combination as joint probabilities.