The performance of passive flow monitors and phosphate accumulating passive samplers when exposed to pulses in external water flow rate and/or external phosphate concentrations

Passive samplers are typically calibrated under constant flow and concentration conditions. This study assessed whether concentration and/or flow pulses could be integrated using a phosphate passive sampler (P-sampler). Assessment involved three 21-day experiments featuring a pulse in flow rate, a pulse of filterable reactive phosphate (FRP) concentration and a simultaneous concentration and flow pulse. FRP concentrations were also determined by parallel grab sampling and the P-sampler calibrated with passive flow monitors (PFMs) and direct measurement of flow rates. The mass lost from the PFM over the deployment periods predicted water velocity to within 5.1, 0.48 and 7.1% when exposed to a flow rate pulse (7.5-50 cm s⁻¹), concentration pulse (5-100 μg P L⁻¹), or both simultaneously. For the P-sampler, good agreement was observed between the grab and passive measurements of FRP concentration when exposed to a pulse in flow (6% overestimation) or concentration (2% underestimation).     

Assessing Effectiveness of National Flood Policy Through Spatiotemporal Monitoring of Socioeconomic Exposure1

Abstract: After a century of evolving flood policies, there has been a steady increase in flood losses, which has partly been driven by development in flood prone areas. National flood policy was revised in 1994 to focus on limiting and reducing the amount of development inside the 100‐year floodplain, with the goal of decreasing flood losses, which can be measured and quantified in terms of population and property value inside the 100‐year floodplain. Monitoring changes in these measurable indicators can inform where and how effective national floodplain management strategies have been. National flood policies are restricted to the spatial extent of the 100‐year floodplain, thus there are no development regulations to protect against flooding adjacent to this boundary. No consistent monitoring has been undertaken to examine the effect of flood policy on development immediately outside the 100‐year floodplain. We developed a standardized methodology, which leveraged national data to quantify changes in population and building tax value (exposure). We applied this approach to counties in North Carolina to assess (1) temporal changes, before and after the 1994 policy and (2) spatial changes, inside and adjacent to the 100‐year floodplain. Temporal results indicate the Piedmont and Mountain Region had limited success at reducing exposure within the 100‐year floodplain, while the Coastal Plain successfully reduced exposure. Spatially, there was a significant increase in exposure immediately outside the 100‐year floodplain throughout North Carolina. The lack of consistent monitoring has resulted in the continuation of this unintended consequence, which could be a significant driver of increased flood losses as any flood even slightly higher than the 100‐year floodplain will have a disproportionately large impact since development is outside the legal boundary of national flood policy.     

理性思考汶川地震中砌体结构的抗震能力

汶川地震建筑震害严重,应对此进行理性的思考。本文立足于按规范正常建造的砌体结构房屋的震害调查,对砌体结构震害严重的原因进行了分析,提出了减轻砌体结构震害的建议;同时,对预制板在地震区的应用进行了探讨,指出政府不宜限制预制板的应用;最后,建议采用经济性好、施工快捷、结构性能可靠的新型装配整体式房屋结构体系等技术。     

基于GIS的洪水淹没评估系统的研究与实现

在G IS技术支持下,对洪水淹没评估系统从洪水淹没计算与洪水淹没评估两方面进行研究,结合湖南冷水滩区洪水淹没评估系统实例,选择了正方形DEM模型,利用正方形格网分析方法进行了洪水淹没中连通性的分析。构建了洪水淹没评估模型,并对洪水淹没评估中的叠置分析提出具体解决思路。最后介绍了系统的设计与实现。     

Embeddedness of climate change adaptation: established procedures and contending discourses for flood protection in Espoo,Finland

Calls for more stakeholder participation and cooperation, the acknowledgement of uncertainties as well as for flexible and robust solutions have become frequent in the literature on climate change adaptation. Recent studies show that these calls are taken up only reluctantly in local adaptation compared to sectoral and technical solutions. The aim of this study is to examine to which extent adaptation as an embedded process within the local context allows for stakeholder participation, cooperation and the robustness and flexibility of adaptation measures. It applies an analytical approach, combining an action framework of adaptation and document-based discourse analysis, to assess both the procedural and the substantive viewpoint of an adaptation case in Finland. This twofold approach provides insight into how the adaptation process and content influence and condition each other. The analysis highlights how new approaches to adaptation have to compete with prevailing discourses and institutionalised practices, as public authorities take the dominant role in adaptation, striving for certain and safe solutions. This process has few participatory elements and leaves little leeway to address uncertainty.     

The Influence of the Pacific Decadal Oscillation on Annual Floods in the Rivers of Western Canada

We analyzed annual peak flow series from 127 naturally flowing or naturalized streamflow gauges across western Canada to examine the impact of the Pacific Decadal Oscillation (PDO) on annual flood risk, which has been previously unexamined in detail. Using Spearman's rank correlation ρ and permutation tests on quantile‐quantile plots, we show that higher magnitude floods are more likely during the negative phase of the PDO than during the positive phase (shown at 38% of the stations by Spearman's rank correlations and at 51% of the stations according to the permutation tests). Flood frequency analysis (FFA) stratified according to PDO phase suggests that higher magnitude floods may also occur more frequently during the negative PDO phase than during the positive phase. Our results hold throughout much of this region, with the upper Fraser River Basin, the Columbia River Basin, and the North Saskatchewan River Basin particularly subject to this effect. Our results add to other researchers' work questioning the wholesale validity of the key assumption in FFA that the annual peak flow series at a site is independently and identically distributed. Hence, knowledge of large‐scale climate state should be considered prior to the design and construction of infrastructure.     

A High‐Resolution National‐Scale Hydrologic Forecast System from a Global Ensemble Land Surface Model

Warning systems with the ability to predict floods several days in advance have the potential to benefit tens of millions of people. Accordingly, large‐scale streamflow prediction systems such as the Advanced Hydrologic Prediction Service or the Global Flood Awareness System are limited to coarse resolutions. This article presents a method for routing global runoff ensemble forecasts and global historical runoff generated by the European Centre for Medium‐Range Weather Forecasts model using the Routing Application for Parallel computatIon of Discharge to produce high spatial resolution 15‐day stream forecasts, approximate recurrence intervals, and warning points at locations where streamflow is predicted to exceed the recurrence interval thresholds. The processing method involves distributing the computations using computer clusters to facilitate processing of large watersheds with high‐density stream networks. In addition, the Streamflow Prediction Tool web application was developed for visualizing analyzed results at both the regional level and at the reach level of high‐density stream networks. The application formed part of the base hydrologic forecasting service available to the National Flood Interoperability Experiment and can potentially transform the nation's forecast ability by incorporating ensemble predictions at the nearly 2.7 million reaches of the National Hydrography Plus Version 2 Dataset into the national forecasting system.     

基于灰色理论的黑龙江省暴雨洪涝特征分析及灾变预测

基于灰色理论和气象灾害普查资料对黑龙江省暴雨洪涝灾害时空分布特征进行了分析并进行了灾变预测。黑龙江省暴雨洪涝灾害主要发生在5-9月,其中7月损失最大;1990年以来暴雨次数虽然有所减少,但暴雨洪涝造成的损失却明显增加;黑龙江省暴雨洪涝灾害可划分为严重洪涝区、重洪涝区、中洪涝区和轻洪涝区,严重洪涝区位于松花江及其支流沿岸的大庆市、伊春市、齐齐哈尔市、佳木斯市和哈尔滨市。根据灰色灾变预测理论预测2013年出现严重暴雨洪涝灾害(全省农作物受灾面积≥500 000 hm2、可比经济损失≥50 000万元)的可能性最大,其次是2016年。     

科技信任、管理信任及其对公众水灾风险认知的影响——基于长江中下游的社会调查

信任和风险在一定程度上互为因果,两者通过认知行为决策及行为后果这一环节构建互馈关系。探索公众对社会减灾能力的信任及其对灾害风险认知的影响机制,有助于揭示灾害风险的潜在因素,调适风险认知与避灾行为,从而降低灾害风险。选取水灾发生频繁、强度大、防洪措施多样的长江中下游地区为研究区,运用随机抽样调查和入户访谈相结合的方式获取资料,研究公众的水灾科技信任和管理信任的水平、影响机制、动机-效应差异。主要结论有:①公众科技信任水平普遍高于管理信任。信任水平受到公众性别、年龄、灾害经历、城乡差异等因素不同程度的影响,信任具有区域共构的特点;②科技信任改变了公众水灾风险认知,加强了其灾害应对信心,降低了其对受灾风险的估测,对其避灾行为倾向影响显著,而管理信任对公众水灾风险认知及防灾备灾行为倾向的影响均不大;③信任的产生动机以认可减灾措施有用性为前提,科技减灾和管理减灾由于具有不同的减灾原理及作用时段,导致了公众的不同信任动机及其效应。     

Coping strategies and risk manageability: using participatory geographical information systems to represent local knowledge

The accumulated knowledge and perceptions of communities 'at risk' are key elements in managing disaster risk at the local level. This paper demonstrates that local knowledge of flood hazards can be structured systematically into geographic information system (GIS) outputs. When combined with forecasting models and risk scenarios, they strengthen the legitimacy of local knowledge of at-risk populations. This is essential for effective disaster risk reduction practices by external actors, local non-governmental organisations (NGOs) and municipal authorities. The research focused on understanding coping strategies and 'manageability' of flood hazards as defined by communities. 'Manageability' is how people experience flooding in relation to their household capacity and the coping mechanisms available. The research in the Philippines highlights the significance of localised factors, including socioeconomic resources, livelihoods, seasonality and periodicity, for understanding manageability. The manageability concept improves practice at the municipal level by legitimising local coping strategies, providing better indicators, and developing understanding of flooding as a recurrent threat.