Urban flood risk assessment using sewer flooding databases (original) (raw)
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Flood Risks in Urban Areas-Data Analysis , Communication and Mitigation
2017
The increased frequency of heavy rainfall events leads to urban flooding, which induces immense damage and thus results in substantial costs in the urban area and in some cases even bodily injuries. The underground sewage systems cannot cope with extreme precipitation events. Enlargement and remediation of sewage systems and the construction of generally underground storm water retention basins alone cannot solve the problem efficiently. Consequently, urban drainage and urban planning authorities have a joint responsibility for recognizing surface run-off in terms of surface and underground flow paths, and also area utilization schemes adapted to the latter. The overall goal is to develop new forms of collaboration and to establish integrated planning processes bearing the needs of “risk management” and “water-sensitive urban design” in mind. If spatial information is made accessible by means of web-based information systems, these processes can be supported in a reasonable fashion.
Developing a risk-based approach to urban flood analysis
Serious flooding in the UK over recent years has increased the attention on urban flooding and highlighted the need to better understand and manage urban flood risk. Further to this, water companies are under increasing pressure to reduce the number of flooding incidents as a result of inadequate network capacity and asset failure.
Natural Hazards and Earth System Science, 2012
Risk analysis has become a top priority for authorities and stakeholders in many European countries, with the aim of reducing flooding risk, considering the population's needs and improving risk awareness. Within this context, two methodological pieces have been developed in the period 2009-2011 within the SUFRI project (Sustainable Strategies of Urban Flood Risk Management with non-structural measures to cope with the residual risk, 2nd ERA-Net CRUE Funding Initiative). First, the "SUFRI Methodology for pluvial and river flooding risk assessment in urban areas to inform decision-making" provides a comprehensive and quantitative tool for flood risk analysis. Second, the "Methodology for investigation of risk awareness of the population concerned" presents the basis to estimate current risk from a social perspective and identify tendencies in the way floods are understood by citizens. Outcomes of both methods are integrated in this paper with the aim of informing decision making on non-structural protection measures. The results of two case studies are shown to illustrate practical applications of this developed approach. The main advantage of applying the methodology herein presented consists in providing a quantitative estimation of flooding risk before and after investing in non-structural risk mitigation measures. It can be of great interest for decision makers as it provides rational and solid information.
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Journal of Environmental Management, 2020
During the period 1998-2017, floods were responsible for 11% of the loss of life and 23% of the economic loss caused by climate-related and geophysical-related disasters worldwide. An integrated and effective definition of flood risk management strategies therefore still requires synthesized and comprehensive knowledge about the driving forces of flood risk. In this study, 278 Portuguese municipalities are analyzed and classified according to flood hazard, exposure, and vulnerability. After evaluating the three components that describe risk, an index of the flood risk is calculated and a cluster analysis is further performed to understand the role of the risk drivers (hazard, exposure, and vulnerability) in each municipality. The proposed approach therefore provides flood risk indexes on a municipal basis, which are built upon different sources of both cell-by-cell data and an aggregation of municipal-level data that has been statistically validated. Municipalities both in the NW part of the country and along the valleys of major rivers demonstrate a significant superimposition of high levels of exposure and hazard, while vulnerability presents a disperse pattern throughout the country. The results obtained using this approach should contribute to the diversification of flood risk management strategies. This is still lacking in the majority of the national-level flood risk governance processes, namely those strategies that focus on the contingency of daily activities and those aiming at a long-term reduction of the exposure, vulnerability, and hazard components that shape flood disasters.
Flood risk assessment in an urban area: Measuring hazard and vulnerability
This paper discusses the three major elements related to the flood potential damages: hazard, vulnerability and risk. The hazard takes into account the probability events as well as their main physical characteristics. The vulnerability refers mainly to the potential losses of flood prone area and the local recovery capacity. The interaction between these two elements indicates the risk level of the exposed area. An index for total risk including sub-indicators is created to describe the flood-prone area and the occurrence of economic damages in Manhuaçu, a Brazilian town with 73000 inhabitants, with frequent flood events. A multiple index brings benefit when representing multiple aspects of an object in an only measure. Factorial analyses and hierarchical cluster analysis are employed to produce the risk index. Flood maps of the urban area are developed with local cartographic information allowing the association of data generated by hydrologic and hydraulic modeling and land use c...
Urban Flood Risk Management: Impact of Combined Strategies
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The sprawling of urban areas combined with the intensification of extreme storm events increases the frequency of floods. The Milan metropolitan area, Italy, is a glaring example of this condition, where floods occur on average two times a year and a new approach for urban water management is required. In recent years sustainable urban drainage systems (SuDs) have been spreading in many cities for local stormwater runoff reduction, in order to reduce the risk of overloading receiving water bodies and sewerage systems. These natural-based techniques also present advantages in terms of water quality improvement and in some cases also provide benefits at the ecological level. For an optimal river basin management, it is necessary to adopt holistic approaches including river restoration measures and SuDs for the hydraulic risk mitigation and the water and environmental quality enhancement. Previous research analysed the impact of re-naturalization measures on a stretch of the Seveso riv...
Attribution of flood risk in urban areas
Journal of Hydroinformatics, 2008
Flooding in urban areas represents a particular challenge to modellers and flood risk managers because of the complex interactions of surface and sewer flows. Quantified flood risk estimates provide a common metric that can be used to compare risks from different sources. In situations where there are several organisations responsible for flood risk management we wish to be able to disaggregate the total risk and attribute it to different components in the system and/or agents with responsibility for risk reduction in order to target management actions. Two approaches to risk attribution are discussed:
Urban planning, flood risk and public policy: The case of the Arno River, Firenze, Italy
Applied Geography, 2012
Urban planning and hydraulic risk management are a worldwide necessity which is best achieved when natural and artificial elements located closely to watercourses are known in great detail. A geodatabase is a practical tool to store and manage such information. When working at small scales, however, any well established methodology exists to map the position and the height of the various elements with centimetric accuracy. For this purpose we propose a methodology that we tested on the Arno river (Italy) and its most urbanized tributaries, a demonstrative case of hydrological risk around large fluvial systems. We surveyed 116 km of river traits to collect GPS measurements and information about all the natural and artificial elements connected to hydraulic risk and fluvial dynamics. The mapped elements include (but are not limited to) buildings, assets, bridges, hydraulic works, weirs, drainage outlets, dikes, riverbanks, structural damages, fluvial bars and eroding banks. All these elements were mapped with high accuracy, in particular a local geoid model, related only to the study area, was developed to obtain orthometric heights affected with errors 0.05 m. Consequently a GIS geodatabase was built to visualize the spatial distribution of the mapped elements and to store a series of technical data, including the present preservation condition for man-made objects. The geodatabase provides an overview of the territories connected with the fluvial dynamics, highlighting that in the studied territory, the more is urbanized, the more it is exposed to hydraulic risk. In a similar context, the geodatabase itself represents a useful tool for the management of the hydrological risk and for hydraulic policy and urban planning.
Estimation of Flooding Risk Indices Using GIS and EO Data
Non-structural measures for water management …
Edited by Slobodan P. Simonovic IHP-V Technical Documents in Hydrology No. 56 UNESCO, Paris, 2002 The designations employed and the presentation of material throughout the publication do not imply the expression of any opinion whatsoever on the part of UNESCO concerning the legal status of any country, territory, city or of its authorities, or concerning the delimitation of its frontiers or boundaries.
A Systemic Approach to Evaluate the Flood Vulnerability for an Urban Study Case in Southern Italy
Journal of Water Resource and Protection, 2014
Currently, the urban flooding is one of the most concerning problems in hydraulic protection, both for the enormous number of people and the different elements (buildings, roads, vehicles, and so on) potentially exposed to risk, as well as the complexity of the territory at issue. At the practical level, vulnerability indicators are often predictably too narrow in their coverage of aspects of vulnerability. An important need remains to produce more conceptually informed vulnerability indicators or parameters and more satisfactory operational tools to assess weaknesses and resilience in coping with natural risks. In this paper, we present an innovative methodology that adopts a systemic approach to evaluate the vulnerability due to a flood scenario. The operative efficiency of the proposed GIS tool is validated in pilot application site, i.e. an urban area in Puglia Region, Southern Italy, on the basis of, studies surveys and damages carried out from a recent flood event occurred in the area. The model evaluates the direct structural damages and explores the potential operating conditions of the road network in case of the flood event. The resulting vulnerability assessment tool can guide evaluators towards a comprehensive understanding of strengths and fragilities of a territory and community where a flood occurs embedding and integrating as much as possible the multifaceted and articulated nature of an urban system.