Assessing the effects of flood resilience technologies on building scale

The impacts of floods on housing are increasing due to more frequent and severe weather events as well as the ongoing development of settlements in flood-prone areas together with the rising vulnerability of assets at risk. Therefore, the improvement of the resilience properties of buildings to better cope with flooding has become a key issue towards more flood resilient cities in European research in recent years. The implementation of flood resilience technologies (FReT) on the individual property scale provides a previously untapped potential to reduce flood damage to buildings due to insufficient transparency of their effects. To overcome this obstacle, the paper presents a four-step extension of a synthetic approach for flood vulnerability analysis to provide evidence on the potential effects of FReT uptake concerning flood damage mitigation. The proposed approach has been integrated in the GIS-based flood damage simulation model HOWAD to support the assessment of FReT alternatives. The simulation of flood damage to buildings in the case study Heywood, Greater Manchester (United Kingdom) revealed the potential of the extended approach to determine the consequences of FReT implementation on building scale.     

Mapping and classification of direct flood impacts in the complex conditions of an urban environment. The case study of the 2014 flood in Athens,Greece

Urban flooding is a gradually increasing problem as the urban population expands into floodplains. In urban environments, flood vulnerability is significantly increased as a more concentrated population and assets makes flooding costly and challenging, in terms of impact estimation. This work focuses on mapping and classifying impacts after the catastrophic 2014 flood in Athens, Greece. The study proposes a method for classifying flood effects into four categories including: the natural and built environment, mobile objects and human population, organized in five classes of increasing severity, i.e. minor, weak, moderate, strong and extreme. Flood effects are grouped based on the qualitative nature of the recorded effects, allowing the development of an impact-severity map. Mapping of the 2014 flood effects indicated specific locations where the severity of impacts was distinctively higher than others, providing a holistic overview of the flood’s effects and highlighting the usefulness of the approach in future flood protection planning.     

Land use regulations and the dispersion of the IT Industry in the San Francisco Bay area

Urban economists have recently found evidence that land use regulations prevent the efficient migration of workers among regions, generating losses in output. By contrast, there is a lack of work that directly considers the relationship between land use regulations and the geography of firms and industries. Since the 1980s, the IT industry has dispersed from its historical core, Silicon Valley, around the broader San Francisco Bay Area. This study finds that restrictive land use practices have limited IT firm creation in Silicon Valley, pushing the industry to less productive parts of the regional economy.     

The Impact of Flooding on the Price of Residential Property: A Transactional Analysis of the UK Market

The increase in frequency and severity of flood events in the UK has highlighted the question of the impact of flooding on the value of property. Previous studies in the UK and internationally have measured a wide variety of impacts from no impact to discounts of more than 40 per cent of property price. Transactional measurements have not previously been attempted in the UK property market due to lack of available data. In order to improve the available evidence base, a variation of the repeat sales methodology has been used to measure the impact of flooding on the price of transacted residential property for 13 locations in the UK. The results reveal the impact of flood events to be highly variable and temporary and no effect of flood designation. The policy implications of these findings with regard to the perceptions and behaviours of property stakeholders are explored.     

A new experiments-based methodology to define the stability threshold for any vehicle exposed to flooding

A vehicle exposed to flooding, after losing stability, becomes buoyant and may be washed away with potential injuries and fatalities. Such vehicles cause additional disruption to traffic that is already affected by flooding, which may lead to substantial indirect economic impact, especially in urban areas. Therefore, the analysis of the stability of vehicles exposed to flooding is important in order to make decisions to reduce damages and hazards. In this research, based on an experimental campaign that included a range of twelve car models, a new methodology to obtain the stability threshold for any real vehicle exposed to flooding is developed. A stability coefficient (SC_mod) is derived with which the vehicles can be sorted by stability against water flows and their stability functions may be determined. The experiments were conducted with three different model scales (1:14, 1:18 and 1:24) and involved analysis of both friction and buoyancy effects, which made this the most comprehensive research study to date. This methodology enables the definition of a stable area in the flow depth-velocity domain for any real vehicle. A tool is provided that decision-makers in the field of urban flood risk management can employ and after defining a design vehicle they can obtain its corresponding stability threshold.     

Utilization of an underground mining evaluation map incorporating the effect of landslides and surface flooding for land-use purpose

A number of problems related to land use and foundations of new structures are encountered in underground mining areas. Potential suitability and/or unsuitability of lands for new structures must be considered in areas affected by underground mining. It is well-known that subsidence, slope instability, and surface flooding are frequently observed in underground mining areas. Thus, a map that takes into account such geo-hazards and classifies suitable and unsuitable areas for new structures is needed. Areas affected by underground mining of coal in Stonava near to the border of the Czech Republic and Poland represent specific areas where subsidence, slope instability, and surface flooding problems need a strategy for future utilization of the landscape by means of land use plans. In light of the above reasons, the methodology and preparation of a map model incorporating the effect of landslides and surface flooding has been introduced in this study. This map depicts three levels of influence (important influence, moderate influence, and negligible influence). Chronological variations in the building site categories in the study area have been analyzed as another part of the study. It was further crucial to consider the current built-up area in the underground mining area, and therefore, its relation to building site categories has also been evaluated. Consequently, the building site categories were evaluated in relation to the planned built-up area, which is the most important landscape element in a land-use plan as a tool in the decision-making process.     

The Flood-Prevention Scheme of Venice: Experimental Module

Records exist of the flooding of Venice from the days of the Republic. During the last century flooding incidents have become more severe due to subsidence of the city and rising water levels in the Adriatic. Calamitous flooding occurred in 1966, and two devastating floods were experienced during the last decade. The 'Special Law for Venice', enacted by the Italian Parliament in 1973, paved the way for a competition to devise a flood-prevention scheme.
A consortium of Italian contractors, who were commissioned to submit proposals for the implementation of the scheme, designated Technital Spa of Verona to carry out the design of the flood-prevention works and improvements within the lagoon. This resulted in the design of three movable barrages to seal off the Venice lagoon in the event of a flood. The construction of a full-size gate and caisson (the prototype of the eighty gates forming the barrages) was subsequently authorized.
This paper describes the experimental module containing the buoyant gate and its caisson, its novel features as well as some of the events leading up to its design and construction.     

Motivations for the San Fernando Valley Secession Movement: The Political Dynamics of Secession

I argue that the motivation for the San Fernando Valley secession movement can be explained as a desire for local control based on democratic ideals, but I emphasize that the movement is also motivated in part by the tangible benefits that accompany such autonomy. After a brief look at possible economic and racial motivations behind the secession movement, I look for a political divide between the city and the Valley, based on literature that has found political divisions between urban and suburban areas. Evidence of a political divide is mixed, but does indicate that the Valley lacks representation in comparison to the rest of the city. Valley residents may also fear increasing minority political power, which could erode the dominance of Valley whites at the polls. There is also evidence that those who favor secession are most dissatisfied with representation and most concerned with getting their fair share of services from the city, indicating a strong desire for more local control. Images of a smaller, more democratic government, and a more engaged local civic community are prime motivations in the Valley’s quest for autonomy, though the possibility of reduced taxes, land use control, and increased political power do offer secessionists clear substantive benefits in addition to more democratic goals.     

增强现实技术于洪水风险沟通中的应用

气候变迁,特别是洪水问题给地处三角洲的城市带来了与日俱增的风险。作为应对手段,提出一种整合性的洪水风险管理方法,该方法确保了洪水风险沟通在洪水风险管理战略中的重要地位。洪水的可视化作为洪水风险沟通的一种工具,在改变人们对洪水风险的观念方面有着强大的作用。它可以通过互动的方式,使当地的利益相关者了解洪水的剩余风险和未来风险。其中增强现实技术作为一种可视化手段,它的快速发展与应用为风景园林设计、规划与教育等领域提供了崭新的交互方式。首先,探讨增强现实技术(AR)在洪水风险沟通中的应用现状,并重点关注增强现实技术的2个关键应用领域:对现场决策的支持和针对高层次设计的可视化与对景观干预的评估。随后,展示一种基于增强现实技术所开发的应用,该款创新性的应用为洪水风险沟通提供了一种轻量化的可视化手段。     

An assessment of the impact of floodplain woodland on flood flows

This paper examines the potential role of floodplain woodland in flood alleviation. In theory, the presence of trees and associated woody debris on the floodplain increases the hydraulic roughness, thus slowing down flood flows and enhancing flood storage. One and two‐dimensional models were used to simulate a 2.2 km reach of river in south‐west England to test this theory for a 1 in 100 year flood using appropriate roughness parameters. Both models predicted a reduction in water velocity within the woodland, increasing water level by up to 270 mm and creating a backwater effect that extended nearly 400 m upstream. Flood storage increased by 15 and 71%, while flood peak travel time was increased by 30 and 140 min for the two scenarios simulated. The results suggest that there is considerable scope for using strategically placed floodplain woodland to alleviate downstream flooding. In particular, it offers a means of tackling the increased flood risk associated with climate change.     

Flash flooding in Spain: geomorphological approaches supporting flood frequency analysis, and the implications for the design of structures

Conventional methods for the estimation of flood frequency are generally based on the statistical analysis of data series resulting from the measurement of water levels at specific locations, which are translated into discharges (m³/s) using standard stage/discharge relationships. Subsequently, these gauged flows are used to identify the largest flood event experienced by a river or catchment, and to produce growth curves used in the estimation of the return periods of specific flood events, as well as in the calculation of discharges for specific required design events (e.g. return period 1 in 100 year). In areas where gauging data records are scarce, and/or the data series are short or interrupted, geomorphological interpretation of the physical environment, dating of fluvial deposits and flooding episodes and hydraulic reconstruction of past flood events can be used as complementary tools aiding conventional hydrological and flood frequency analysis methods. This paper will discuss the undertaking of this approach in the Guadalope Catchment in northeast Spain. It will examine the findings in relation to the inadequate design of existing structures such as dams, spillways, canals and reservoirs, and will also look at the potential risks associated with flooding at present.     

太湖流域洪水灾害损失及致因分析

结合太湖流域1999年的洪水灾害,阐述了洪水灾害的损失分类,分析指出太湖流域1999年的洪灾为巨灾,指出太湖流域应制定超标准洪水的应急预案,以减少局部受淹城区的洪灾损失。     

Using building simulation to model the drying of flooded building archetypes

With a changing climate, London is expected to experience more frequent periods of intense rainfall and tidal surges, leading to an increase in the risk of flooding. This paper describes the simulation of the drying of flooded building archetypes representative of the London building stock using the EnergyPlus-based hygrothermal tool ‘University College London-Heat and Moisture Transfer (UCL-HAMT)’ in order to determine the relative drying rates of different built forms and envelope designs. Three different internal drying scenarios, representative of conditions where no professional remediation equipment is used, are simulated. A mould model is used to predict the duration of mould growth risk following a flood on the internal surfaces of the different building types. Heating properties while keeping windows open dried dwellings fastest, while purpose built flats and buildings with insulated cavity walls were found to dry slowest.     

Monitoring a flood event in a densely instrumented catchment, the Upper Eden, Cumbria, UK

Multi‐day rainfall events appear to be an important cause of recent flooding in the UK. Hydrological data from an extensive, nested hydrometric network in the unregulated, predominantly rural Upper Eden catchment in northern England are presented for one such flood event. These highlight antecedent catchment conditions and the propagation of the multi‐day flood event during February 2004. An assessment of flood response is provided over varying scales and land use between the upland Gais Gill catchment (1.1 km²) and the larger Upper Eden catchment (616 km²). Large spatial variations in rainfall totals are identified from a dense raingauge network during the flood event and are principally related to catchment elevation. High cumulative rainfall totals for the 6‐day event, particularly at upland sites appear to be the exceptional feature of the flood event with return periods in the order of 100 years at some upland gauges. Resultant patterns of flood attenuation and translation are quantified in different areas of the catchment, highlighting the flashy response of the headwater catchments and the attenuated downstream response in the lowland environment. The study forms part of the national Catchment Hydrology And Sustainable Management (CHASM) programme.     

长汀城市建设区洪水淹没风险研究

洪水淹没风险分析是进行城市防洪安全研究、合理布局城市建设用地的主要依据之一。本文基于GIS栅格数据空间分析技术,结合了传统淹没分析方法,使用长汀城市建设区地形和洪水水文数据资料,对研究区在10%、5%、2%三种频率下的洪水淹没风险进行了定量化分析,提出了城市建设用地控制原则,为城市规划中协调城市防洪安全与城市建设用地布局提供了有价值的参考。研究结果显示研究区洪水淹没风险总体上较高,城市已建设区洪水淹没风险高于其他区域。     

Design hydrograph and routing scheme for flood mapping in a dense urban area

Definition of flood risk maps is a task to which modern surface hydrology devotes substantial research effort. Their impact on the management of flood-prone, dense, urban areas has increased the need for better investigation of inundation dynamics. The problems associated with the aforementioned topics range from the definition of the design hydrograph and the identification of the surface boundary conditions for the flood routing over the inundation plan, to the choice of the hydrodynamic model to simulate urban flooding. Most of academic and commercial mathematical models, solving the De Saint Venant equations, fail on complex topography. Frequently encountered difficulties concern steep slopes, geometric discontinuities, mixed flow regimes, and initially dry areas. In the present paper, flood routing modelling approaches in urban areas and principles for the definition of the design flood events are outlined. The paper shows how urban flooding can be simulated by a quasi-2D hydrodynamic model that makes use of a network of connected channels and storages to simulate flow, respectively, on the streets and into the building blocks. Furthermore, the paper shows that, when flood hazard is assessed by considering flood extent, water depth and flow velocity, an in-depth analysis of the use of design hydrographs that maximise peak flow or inundation volume is needed.     

Integrated flood plain management strategy for the Vaal

Owing to development pressure for land bordering the Vaal river, in South Africa. Rand Water are revising their development policy. Restrictions were in place to avoid flooding and obstructing the flood flow of the river. Relaxation of the regulations will permit controlled development along the river. A flood hazard-risk index was developed to indicate where development could be permitted. An economic comparison of costs and benefits supports the relaxation.     

Coping strategies of households affected by flooding: A case study of Sekondi-Takoradi Metropolis in Ghana

Annually, rivers close to communities within Sekondi-Takoradi Metropolis overflow their banks, especially during the rainy seasons; displacing thousands of residents. Despite this, little is known about the coping strategies used by the residents when flooding occurs. Using mixed method, this article examines the coping strategies employed by households within three communities at risk. Two hundred and seven heads of households residing in Eshiem, Kansawurodo and Whindo were systematically selected to fill in questionnaires, while six key informants comprising chiefs and representatives of flood management institutions were chosen for in-depth interviews. The findings suggest that the commonest coping strategies adopted by residents in all the communities were: temporary vacation of homes, transfer of relevant properties to neighbors and building of flood steps. However, the coping strategies employed by the residents varied by communities, although the majority of them resorted to self-sustaining mechanisms in restoring their losses.     

Investigative modelling of the flood bypass channel in Kuching,Sarawak, by assessing its impact on the inundations of Kuching-Batu Kawa-Bau Expressway

Flood risks not only include loss of human lives and properties, but also the transportation and communication. One major road in Kuching, the Kuching-Batu Kawa-Bau Expressway is often flooded and interrupted by floodwaters from Sarawak River. The Sarawak State Government had announced to build a flood bypass channel in Sarawak River to mitigate flood under the Ninth Malaysian Plan. This paper is a study on the effects of the structure in the flooding of the mentioned road stretch. The January 2004 event which is locally known as a 100-year flood, was run through a developed river model incorporated with the bypass facilities. The model had indicated a reduction of 53% of flooded road. Similarly, modelling of 10 and 50-year design floods had predicted over 50% of reduction. The bypass channel was said to be able to alleviate the flooding on the major road stretch.