Developing probabilistic eruption forecasts for dormant volcanoes: a case study from Mt Taranaki,New Zealand

The majority of continental arc volcanoes go through decades or centuries of inactivity, thus, communities become inured to their threat. Here we demonstrate a method to quantify hazard from sporadically active volcanoes and to develop probabilistic eruption forecasts. We compiled an eruption-event record for the last c. 9,500 years at Mt Taranaki, New Zealand through detailed radiocarbon dating of recent deposits and a sediment core from a nearby lake. This is the highest-precision record ever collected from the volcano, but it still probably underestimates the frequency of eruptions, which will only be better approximated by adding data from more sediment core sites in different tephra-dispersal directions. A mixture of Weibull distributions provided the best fit to the inter-event period data for the 123 events. Depending on which date is accepted for the last event, the mixture-of-Weibulls model probability is at least 0.37–0.48 for a new eruption from Mt Taranaki in the next 50 years. A polymodal distribution of inter-event periods indicates that a range of nested processes control eruption recurrence at this type of arc volcano. These could possibly be related by further statistical analysis to intrinsic factors such as step-wise processes of magma rise, assembly and storage.     

Urban land consolidation: a review of policy and procedures in Indonesia and other Asian countries

Many Asian mega-cities are growing rapidly and they face formidable urban problems: unplanned squatter settlements, inadequate infrastructure and basic amenities. Smaller Asian urban areas also need badly the provision of basic infrastructure and facilities. However, efforts to improve are often constrained by either nonavailability of suitable land or its exorbitant cost. Strategies such as land consolidation have shown considerable promise. Implementation of the strategy varies from country to country and from project to project. In general, the land consolidation approach is participatory in nature and places emphasis on in situ development with voluntary contribution of private assets by affected households in need of infrastructure and basic services. However, to make any significant impact of the land consolidation strategy on urban development, financial support from multilateral agencies such as the World Bank is necessary. To enable this it is necessary that the policy and implementation procedures fully conform to the objectives of the World Bank's safeguard policies such as OD 4.30 `Involuntary Resettlement'. This study reviews the land consolidation policies and procedures as applied in several Asian countries in general, and in Indonesia in particular. The objective is to identify the gaps that exist between the policy and procedures and that of the objectives of the World Bank's Policy of Involuntary resettlement and to recommend general policy and procedural guidelines for land consolidation projects that would enable financial support from multilateral agencies such as the World Bank. This revised version was published online in July 2006 with corrections to the Cover Date.     

地下水更新能力评价指标问题刍议——更新周期和补给速率的适用性

地下水更新能力是近些年地下水科学与工程领域的一个研究热点,其定义目前尚未统一,评价指标也较多,其中较常用的有地下水更新周期、补给速率、年龄和滞留时间等。尽管这些参数间大都存在一定的数量关系,但由于它们代表的物理意义不同,所以得到的地下水更新能力的结论也会不同。以北京市平原区地下水为例验证了这种不同,并对更新周期和补给速率这两个存在密切数量关系的参数作为地下水更新能力评价指标的适用性进行了对比分析。结果表明:① 分别用更新周期和补给速率作为评价指标,得到的各地区(北京市平原区各区、县)之间地下水更新能力相对强弱的结论是不同的;② 与更新周期相比,由补给速率得到的评价结论具有较好的稳定性;③ 在作为地下水更新能力评价指标时,补给速率比更新周期具有更重要的实际意义。     

城市功能空间更新研究进展与新时期重点方向

文章首先基于西方城市更新发展历程,界定了城市功能更新的概念内涵,进而围绕城市功能更新背景与演替轨迹、城市功能更新类型与组织模式、城市更新空间模拟识别与评价、城市功能更新驱动机理与规划调控等国内外研究进展进行系统梳理,研究发现,城市功能更新趋势与经济社会发展水平、城市化所处阶段紧密相关,更新运作模式体现为政府、私有部门和社区等多元合作倾向,更新判定趋于多源数据融合辨识,更新策略的制定受政策调控力、经济驱动力、市场机制等多重因素叠加影响。基于此,伴随新时期中国城市发展转型调整,城市功能更新研究更加重视对更新实践的科学性认知、空间治理能力的精细化转向、治理理念的人本化回归,并主要聚焦城市功能更新理论体系与实操框架的构建、功能业态演替特征的精细考量、更新调控的因地施策等新时期研究热点。但既有研究主要从城市与区域宏观尺度上对单一功能类型的更新模式进行定性描述,对微观视阈下精细功能业态演替的多时相认知与客观评价仍显不足。为此,提出未来中国城市功能更新应重视加强微观空间尺度下功能业态更新模式的多维度量化解析研究;在研究方法上,应注重融入系统学研究思想及其综合方法。     

从市区到市郊:二战后联邦政府主导下的美国郊区化运动

二战后,为解决严重的住房短缺问题,美国联邦政府一方面继续鼓励发展郊区住宅,如为退伍军人制定优惠贷款政策、修建州际高速公路,另一方面发起了城市更新运动,试图通过拆除城市中心衰败社区来改善居住环境,为城市中心的发展注入新的活力。然而,这些政策在推动郊区化的同时,也加剧了城市中心的衰落。这些政策的实施,既塑造了战后美国城市面貌,也对诸如城市暴乱、社会分化等问题负有责任。     

城中村可持续更新路径探索 ——以长沙后湖黄鹤村为例

城中村更新的方式主要有两种:一种是拆迁重建,另一种是就地整改;两种方式均难以满足城市对经济、社会、环境等多元目标的可持续发展需求,成为制约城市更新进程与效果的关键因素.基于此,引入可持续性科学理论,并借鉴管理学中"对象-主体-过程"的三维分析框架,以社区及单个项目作为研究的空间尺度,构建了城中村可持续更新模式的研究框架...     

基于城市地块变化的基准地价更新研究

采用传统的方法编制地价指数及更新基准地价需要大量的地产交易资料,而我国大多数城镇地产交易市场尚未发育完善,存在收集资料困难,操作难度大等问题。文中在研究城市地块变化及其测度的基础上,通过分析地块变化指数和地价指数之间的相关性,建立了相关模型,从而测算出地价指数并更新基准地价。以土地市场发育不太完善的广西县级城市——桂平市为例进行了实证研究,并采用德尔菲法对结果的合理性进行了分析。结果显示,专家评价平均值为49.83,标准差为2.256 7,符合度为99.66%,说明基于地块变化的基准地价更新的方法是科学可行的。     

Enacting immanent potentialities: Tcheb‐tchib strategies at the centre of the urban fringe in Nouakchott,Mauritania

The urban fringe areas of Nouakchott, the capital city of the Islamic Republic of Mauritania, have become virtual epicentres of informal property speculation, as the state‐owned land that people illegally inhabit becomes an increasingly valuable commodity in the wake of urban redevelopment plans and vast infrastructural development projects. By applying ingenious ‘poaching’ strategies based on anticipation, the marginalized, impoverished people inhabiting these areas appropriate and manipulate space in order to survive. In their attempt to counter the state's technologies of governance through what is commonly known as tcheb‐tchib, a form of creative improvisation, they become a driving force in the dynamic and contested reconfigurations of the urban landscape. Based on extended ethnographic fieldwork focusing on the strategies of former nomads who are now sedentarized on the urban fringe, this article conceives large‐scale urban renewal as a dynamic process that generates an emergent space of immanent potentiality that the urban poor attempt to strategically appropriate and enact to make the most of a potentially destructive process.     

Air-Sea Exchange of Volatile Organic Compounds: A New Model with Microlayer Effects

The authors propose a new “three-layer” conceptual model for the air-sea exchange of organic gases, which includes a dynamic surface microlayer with photochemical and biological processes. A parameterization of this three-layer model is presented, which was used to calculate the air-sea fluxes of acetone over the Pacific Ocean. The air-sea fluxes of acetone calculated by the three-layer model are in the same direction but possess half the magnitude of the fluxes calculated by the traditional two-layer model in the absence of photochemical and biological processes. However, photochemical and biological processes impacting acetone in the microlayer can greatly vary the calculated fluxes in the three-layer model, even reversing their direction under favorable conditions. Our model may help explain the discrepancies between measured and calculated acetone fluxes in previous studies. More measurements are needed to validate our conceptual model and provide constraints on the model parameters.     

空间句法在规划方案设计中的应用——以株洲建宁老区为例

空间句法作为一种重要的理解空间形式和功能的理论、空间描述手段和情景分析工具,为城市中老城区的更新规划分析和方案设计提供了一种新思路.该文利用空间句法轴线图模型,选择了整合度、平均深度和智能度分析参量,分析了株洲市建宁老区的空间结构,并对规划方案做了评价.应用结果证明了空间句法对规划中经常出现的前期研究和空间设计方案之间“断层”问题有所改进,提高了规划的科学性和有效性.