Showing papers in "Journal of Flood Risk Management in 2018"

Multi‐temporal synthetic aperture radar flood mapping using change detection

Abstract: A change detection and thresholding methodology has been adapted from previous studies to determine the extent of flooding for 13 Sentinel-1 synthetic aperture radar images captured during the floods of winter 2015–2016 in Yorkshire, UK. Both available polarisations, VH and VV, have been processed to allow for a comparison of their respective accuracy for delineating surface water. Peak flood extents are found on 29 December 2015 during the aftermath of storms Eva and Frank. Results have been validated against a Sentinel-2 optical image, with both polarisations producing a total accuracy of 97%. Of the two polarisations, VV produces fewer misclassifications, mirroring the similar results reported in previous research. Mapped results are compared to the Environment Agency Flood Maps for Planning (EA FMP), with good correlation observed for inundation on the floodplains. Differences occur away from the floodplains, with the satellite data identifying pluvial flooding not highlighted by the EA FMP.

Overcoming uncertainty and barriers to adoption of Blue-Green Infrastructure for urban flood risk management

Abstract: Blue-Green Infrastructure (BGI) and Sustainable Drainage Systems (SuDS) are increasingly recognised as vital components of urban flood risk management. However, uncertainty regarding their hydrologic performance and lack of confidence concerning their public acceptability create concerns and challenges that limit their widespread adoption. This paper investigates barriers to implementation of BGI in Portland, Oregon, using the Relevant Dominant Uncertainty (RDU) approach. Two types of RDU are identified: scientific RDU’s related to physical processes that affect infrastructure performance and service provision, and socio-political RDU’s that reflect a lack of confidence in socio-political structures and public preferences for BGI. We find that socio-political RDU’s currently exert the strongest negative influences on BGI decision making in Portland. We conclude that identification and management of both biophysical and socio-political uncertainties are essential to broadening the implementation of BGI and sustainable urban flood risk management solutions that are practical, scientifically sound, and supported by local stakeholders.

Characterising flash flood response to intense rainfall and impacts using historical information and gauged data in Britain

Abstract: We analyse chronologies of historical flash floods derived from searches of newspaper archives and other sources commencing before 1800 and recent gauged rainfall and stream flow data. Five key examples are chosen to illustrate specific features of flash floods. Pluvial flash floods arise from rainfall before it reaches a watercourse and may cause severe flooding of land and properties far from rivers. River flash floods, like pluvial floods, have the characteristic of rapid speed of response, a principal source of risk to life. Intense rainfall can generate ‘walls of water’ in river courses which can propagate long distances downstream and steepen, without upstream structural failure. Steeply rising wavefronts more commonly occur on steep upland catchments but, where intensities of extreme short period rainfall are sufficient, such wavefronts can also occur on lowland catchments. A definition of flash floods from intense rainfall, relevant to British landscape and climate, is proposed.

Critical infrastructure impact assessment due to flood exposure.

Abstract: Critical national infrastructures, including energy, transport, digital communications, and water, are prone to flood damage. Their geographical extent is a determinant of, and is determined by, patterns of human development, which is often concentrated in floodplains. It is important to understand how infrastructure systems react to large-scale flooding. In this paper, we present an integrated framework for critical infrastructure flood impact assessment. Within this integrated framework, we represent interdependent infrastructure assets through spatial network models. We quantify infrastructure flood impacts in terms of disrupted customers linked directly to flood assets and customers disrupted indirectly due to network effects. The analysis shows how spatial network models inform flood risk management practitioners to identify and compare critical infrastructures risks on flooded and non-flooded land, for prioritising flood protection investments and improve resilience of cities. A case study of the Thames catchment in England is presented, which contains key infrastructure assets and highest population concentrations in United Kingdom.

Realizing the potential of Natural Water Retention Measures in catchment flood management: Tradeoffs and matching interests

Abstract: Natural Water Retention Measures (NWRM) are a multi-functional form of green infrastructure that can play an important role in catchment-scale flood risk management. While green infrastructure based on natural processes are increasingly recognized as being complementary to traditional flood control strategies based on grey infrastructure in urban areas, there are a number of outstanding challenges with their widespread uptake. At a catchment scale, it is widely accepted that NWRM in upstream areas based on the concept of “keeping the rain where it falls” can help reduce the risk of downstream flooding by enhancing or restoring natural hydrological processes including interception, evapotranspiration, infiltration and ponding. However, both the magnitude of flood risk reduction and the institutional structures needed for widespread uptake of NWRM are inadequately understood. Implementing NWRM can involve tradeoffs, especially in agricultural areas. Measures based on drainage management and short rotation forestry may help “keep the rain where it falls” but can result in foregone farm income. To identify situations where implementation of NWRM may be warranted, an improved understanding of the likely reductions in downstream urban flood risk, the required institutional structures for risk management and transfer and mutually acceptable farm compensation schemes are all needed.

A review of the flood risk management governance and resilience literature

Abstract: The environmental management literature suggests that resilience is key to managing complex systems and reducing vulnerability resulting from uncertainty and unexpected change. Yet, flood risk management (FRM) has emerged largely from a culture of resistance. This paper takes the pulse of the current state of FRM research, with a focus on how the scholarly community has approached governance for flood resilience. Our analysis of the FRM journal literature identified 258 articles addressing governance and flooding, resilience and adaptation. Five main research themes emerged from these articles, addressing a variety of issues, but mostly lacking the degree of integration needed to address the social-ecological complexity of FRM. Overall, research supporting the governance of FRM for resilience lacks integration, and methods of mitigating this lack of integration are poorly studied. We conclude with a discussion about the nature and scope of FRM research for resilience, and identify opportunities for more integrative FRM research that is more tightly coupled with policy and practice.

Assessment of future flood inundations under climate and land use change scenarios in the Ciliwung River Basin, Jakarta

Abstract: This study assessed flood inundation of the Ciliwung River Basin, Greater Jakarta to improve the urban water environment under climate change and unplanned urbanization. The 1-day maximum precipitation data for 50- and 100-year return period under current and future climate conditions were used to assess the impact of climate change. Precipitation output of the MRI-CGCM3, MIROC5 and HadGEM2-ES General Circulation Models (GCM) with RCP 4.5 and 8.5 emission scenario over periods 1985–2004 and 2020–2039 representing current and future climate conditions respectively were used. Similarly, land use data of 2009 and 2030 were used to represent the current and future conditions, respectively. The HEC-HMS model was used to simulate the river discharge at Katulampa, which represents the outlet location for the hydrologic modelling and the inlet location for the flood inundation modelling. FLO-2D, a two-dimensional hydrodynamic model, was used to simulate current and future flood inundation simulations. Increasing flood inundation areas and depths (6% to 31% for different GCMs) in the future reveal the need to improve flood management tools for the sustainable development of urban water environments.

Delivering Green Streets: An exploration of changing perceptions and behaviours over time around bioswales in Portland, Oregon

Abstract: © 2015 The Authors. Journal of Flood Risk Management published by The Chartered Institution of Water and Environmental Management and John Wiley & Sons Ltd. Green Infrastructure (GI) is an increasingly popular means of dealing with flooding and water quality issues worldwide. This study examines public perceptions of, and behaviour around, bioswales, which are a popular GI facility in the United States. Bioswales are highly visible interventions requiring support from residents and policy-makers to be implemented and maintained appropriately. To understand how the residents' perceptions and attitudes might develop over time, we interviewed residents of Portland, Oregon, living near bioswales installed 1–2, 4–5 and 8–9 years ago, to determine awareness, understanding, and opinions about the devices. We found no consistent patterns across time periods, but did find common issues affecting residents' appreciation and acceptance: environmental attitudes, awareness and understanding of purpose and function, plant choice and maintenance, and mess and littering. It was apparent that increased public engagement, localised maintenance strategies, and possibly even customising facilities to meet residents' needs where feasible, might improve acceptance.

Stability criteria for flooded vehicles: a state‐of‐the‐art review

Abstract: Hazard conditions related to vehicular circulation are important in flood risk management. The knowledge of vehicles stability when those are exposed to flooding is crucial for an informed flood risk management in urban areas. After losing stability, the vehicle becomes buoyant and may be washed away with potential injuries and fatalities. Therefore, the analysis of the stability of vehicles exposed to flooding is important in order to make decisions to reduce the damages and hazards. Herein a comprehensive state-of-the-art on stability of vehicles exposed to flooding is presented. The different studies have been gathered in experimental, theoretical and guidelines proposals and all of them focusing on parked vehicles. There is a clear need to conduct more research in this field by testing a greater variety of models in order to offer a more general methodology to define stability threshold for any vehicle exposed to flooding. Nevertheless, in this work, it has been demonstrate that the most safety stability criterion for vehicles exposed to flooding up to now is the proposed in the Guide AR&R.

A methodology for flood susceptibility and vulnerability analysis in complex flood scenarios

Abstract: Nowadays, flood risk management is gaining importance in order to mitigate and prevent flood disasters, and consequently the analysis of flood risk components is becoming a key research topic. In this paper, we propose a methodology for large-scale analysis of flood susceptibility and vulnerability. The methodology is based on a mathematical index, which considers local topography and basic information about the flood scenario to reproduce flooding processes. Its application allows for considering different levels of complexity of flood scenarios, from localized flood defence failures to complex hazard scenarios involving river reaches. The methodology synthesizes the spatial distribution of the index values into maps and curves that can be used to rank the susceptibility and implement a vulnerability analysis in the area of interest. The components of the methodology are tested in two flood plain areas in Northern Italy recently affected by floods. The results show that the methodology can provide an original and valuable insight of flood susceptibility and vulnerability processes.

Modelling urban floods at sub-metre resolution: challenges or opportunities for flood risk management?

Abstract: In this study, we investigate the influence of fine-scale changes in the elevation of urban terrains on the dynamics and final distribution of flood inundation generated by intense rainfall. Numerical experiments have been performed combining two-dimensional shallow water model with extremely fine-resolution (10 cm) terrain data. Our results reveal that localised, decimetric-scale alterations in the elevation of streets can lead to remarkable differences in the flood inundation. These results confirm the important role played by finely resolved and accurate terrain data in capturing flow patterns that have a central impact on model predictions of flood inundation. Also, we argue that the observed sensitivity of flood inundation to small-scale topographical features paves the way to new opportunities for flood risk management measures. In particular, engineering flood resilient urban surfaces using fine-resolution models has a potential to considerably reduce flood impacts at a relatively low cost.

Pluvial flooding in urban areas: the role of surface drainage efficiency

Abstract: Pluvial flooding in urban areas may derive from the limited or temporarily reduced efficiency of surface drainage, even when the underlying storm sewers are properly designed. This study focuses on the impact of uncertainties in the operational condition of the surface drainage system on pluvial flood hazard. The flood propagation model FLURB-2D is implemented on a selected study area in the town of Genoa (Italy). Synthetic hyetographs based on the Chicago and bivariate copula methods with suitable return periods are used as input. While simulating the design rainfall, inlet operational conditions are varied stochastically using a Monte Carlo approach. Results confirm that microtopography has the potential to impact the efficiency of surface drainage and consequently to produce local flooding, with significant water depth in zones of flow concentration. Furthermore, the derived inundation maps allow the highlighting of areas with insufficient design of the surface drainage system (inlet size and positioning).

Assessing and mapping flood hazard, vulnerability and risk in the Upper Brahmaputra River valley using stakeholders’ knowledge and multicriteria evaluation (MCE)

Abstract: Assessing flood hazard, vulnerability and integrated risk has long been recognised as an important input for the formulation of policies aiming at flood risk management. This investigation is an endeavour to assess hazard, vulnerability and risk due to flooding, using an indicator-based methodology incorporating stakeholders’ knowledge and multicriteria evaluation in geographic information system (GIS) to achieve community-based assessment. The framework developed in this work is illustrated for the district of Dhemaji, a chronically flood-affected area in the Upper Brahmaputra River valley. Results show spatial distribution of hotspots of flood hazard and vulnerability and locations at risk at regional and subregional level. The emerged risk pattern indicates that vulnerability indicators are more significant contributors than hazard indicators while calculating risk for the Upper Brahmaputra River valley. The methodology provides a dynamic platform where the flexibility in uses of hazard and vulnerability indicators, depending on variation in physical and socioeconomic setup, is possible.

Assessing and mitigating large wood‐related hazards in mountain streams: recent approaches

Abstract: The assessment and mitigation of floods in mountain streams, when large wood (LW) is transported, pose several challenges. The process chain consisting of flood propagation, LW recruitment, entrainment, transport, and entrapment triggers, at critical sections such as bridges, unexpected and exacerbated impacts to the exposed built environment. We provide a review on the recent advances in modelling LW dynamics during extreme river floods through computational approaches. Moreover, we describe how scaled flume experiments can enhance process understanding at critical flow sections such as bridges to address risk mitigation problems. Additionally, we present a framework based on Formative Scenario Analysis (FSA) to allow for expert knowledge integration and to subsequently derive consistent hazard process scenarios in steep mountain streams where the application of computational approaches is less reliable. Finally, we discuss how the application of the presented set of assessment methods can support integral flood risk management by explicitly considering LW dynamics since the effectiveness of mitigation critically depends on the acquired process understanding.

Housing bubbles and the increase of flood exposure. Failures in flood risk management on the Spanish south-eastern coast (1975–2013)

Abstract: In recent decades, there has been a significant increase in economic losses caused by flood events on the coastal region of south-eastern Spain. The increase of extreme rainfall events forecast by the climate change models is currently not reflected in the statistics which suggests that the principal cause is due to the exposure experienced within the past 40 years. Consequently, it is interesting to evaluate the effect of urban growth in flood-prone areas and the role played by government institutions in mitigating the increase in exposure. For this study, the cadastral information and the hydrological modelling data for the return periods of 10, 50, 100 and 500 years were used. This allows high-resolution spatial–temporal results to be obtained that show one of the most significant growths in exposure in Spain and Europe, as well as the low efficiency that risk mitigation measures have had.

The Influence of Floodplain Restoration on Flow and Sediment Dynamics in an Urban River

Abstract: This article is freely available via Open Access. Follow the DOI to read the whole article on the publisher's website.

Impact assessment of rainfall scenarios and land-use change on hydrologic response using synthetic Area IDF curves

Abstract: In combination with land use change, climate change is increasingly leading to extreme weather conditions and consequently novel hydrologic conditions. Rainfall Area intensity-duration-frequency (IDF) curves, commonly used tools for modeling hydrology and managing flood risk can be used to assess hydrologic response under extreme rainfall conditions. We explore the influence of land use change on hydrologic response under designed extreme rainfall over the period 1976 to 2006 in the Kamo River basin. Run-off for all six designed rainfall shapes under 2006 land use is higher than that under 1976 land use, but the timing of peak discharge under 2006 land use occurs at roughly the same time as that under 1976 land use. Results indicate that run-off under 2006 land use yielded higher discharge than under 1976 land use, and rainfall shape six leads to the most extreme hydrologic response and most dangerous conditions from the perspective of urban planning and flood risk management. Future hydrologic response will differ from present due both to changes in land cover and changes in extreme rainfall patterns requiring modification to Area IDF curves for catchments.

Challenges to enabling and implementing Natural Flood Management in Scotland

Abstract: The research for this paper was supported by the Scottish Government RESAS Strategic Research Programme 2011–2016.

Design hydrograph estimation in small and fully ungauged basins: a preliminary assessment of the EBA4SUB framework

Abstract: Design hydrograph estimation in small and ungauged basins is still a critical issue in hydrological studies. Although a great effort has been devoted to improving the knowledge on this topic in the last 10 years, some unresolved problems still limit the practitioners. Indeed, in small and ungauged watersheds located in areas where regionalisation analyses are not available, hydrologists still typically apply the rational formula. In a recent contribution, we proposed an event-based framework illustrating its potential benefits over the widely used rational formula and underlining its tendency to be less sensitive and less subjective. In the present contribution, we present a preliminary assessment of the proposed framework, analysing its application to five watersheds for which enough observed data are available to provide an evaluation of the model's performance. Although the results confirm that the design hydrograph estimation in small and ungauged basins is affected by relevant errors and uncertainty, they also show that the proposed framework is promising for practical hydrology.

Challenges for achieving sustainable flood risk management

Abstract: This paper presents the challenges for effectiveness and sustainability of flood risk management strategies and technologies by critically reviewing flood management practices. The study reveals that reliable flood prediction is limited by the characterisation of floods that have multiple causes and hydrological uncertainties due to variability in climate and river morphology. Moreover, changing land use in floodplains and the potential of creating new risks limit the risk assessment and evaluation process of flood control projects. Hence, sustainability analysis mechanisms, including ‘dynamic sustainability’ concepts, should be adopted in the flood management planning process. Investigations into the proportional contribution of structural and non-structural measures to reduce total flood risk could assist in better decision making. Gaining improved understandings of the perception on flood risk and safety, and risk communication methods, for present and future stakeholders is crucial. Extensive research on the above challenges would reveal pathways for developing sustainable flood risk management strategies.

Contributing to urban resilience to floods with neighbourhood design: the case of Am Sandtorkai/Dalmannkai in Hamburg

Abstract: On‐going changes in cities caused by rapid urbanisation and climate change have increased both the flood probability and the severity of flooding. Consequently, there is a need for all cities to adapt to climate and socio‐economic changes by developing new strategies for flood risk management. The following risk paradigm shifts from traditional to more integrated approaches, since one of the main emerging tasks for city managers is the development of resilient cities. The concept of resilience is becoming more and more important, despite the many challenges that interfere with its implementation. The goal of this research is to create knowledge on how to operationalise flood resilience at the neighbourhood level through neighbourhood design. A research approach was used and a qualitative analysis tool, the DS3 model, was developed in order to study a particular neighbourhood of HafenCity, in Hamburg. Results show that design measures involving transportation infrastructure, land use (open public spaces) and buildings have been the main contributions to the flood resilience of the neighbourhood.

Hazard mitigation of glacial lake outburst floods in the cordillera blanca (Peru): The effectiveness of remedial works

Abstract: Almost 40 glacial lakes have been remediated in the Cordillera Blanca since the 1940s by implementing different types of structural measures to prevent (mitigate) glacial lake outburst floods. These are (1) open cuts; (2) artificial dams; (3) tunnels; and their combinations. The first part of the paper provides an overview and description of the implemented remedial works. In the second part, the effectiveness of these remedial works is evaluated on the basis of a comparison of the quantified susceptibility of nine selected lakes to outburst floods before and after remediation. Our investigation showed that different types of remedial works have different impacts on the susceptibility of a given lake to outburst floods and are effective for different scenarios (causes and subsequent mechanisms) of outburst floods. Hazard management implications in the framework of risk management and ongoing geo-environmental change are also discussed.

Stability and change in flood risk governance: on path dependencies and change agents.

Abstract: This article presents a theoretical framework for the analysis of stability and change in national flood risk policies. Based on thorough scrutiny of existing theories on stability and change in the literature, we want to offer guidance for empirical studies on flood risk governance. On one hand, we elaborate theories of path dependency and institutional stability. On the other hand, we focus on the role of policy entrepreneurs and actor coalitions bringing in new ideas on how policies should be adjusted. We translate both angles to the realm of flood risks. Furthermore, we consider the role of trends and shock events. By integrating these perspectives into one comprehensive theoretical framework, we aim to offer guidance to empirical researchers searching for forces of stability and change in flood risk governance.

On the impact of urbanization on flood hydrology of small ungauged basins: the case study of the Tiber river tributary network within the city of Rome

Abstract: The small ungauged basins of the highly urbanized area of the city of Rome are often the subject of critical flood conditions for the significant human-made transformations. In this work the EBA4SUB framework, implementing the hydrogeomorphic width function instantaneous unit hydrograph rainfall run-off model, and using digital elevation model, land use and synthetic precipitation as main input information, is applied for evaluating extreme hydrologic forcing conditions at the basic scale. The goal is to understand the rationale behind the observed increasing frequency of local urban inundations that are also observed in the uplands. Results present the impact of urbanization expressed by both the run-off coefficient, the artificial drainage, impacted by paved surfaces and a dramatic number of river–road intersections (i.e. culverts), and the upstream to downstream non-natural scaling behaviour of hydrologic parameters and in particular the peak discharge per unit drainage area.

A new methodology for modelling of health risk from urban flooding exemplified by cholera: Case Dhaka, Bangladesh

Abstract: The phenomenon of urban flooding due to rainfall exceeding the design capacity of drainage systems is a global problem and can have significant economic and social consequences. This is even more extreme in developing countries, where poor sanitation still causes a high infectious disease burden and mortality, especially during floods. At present, there are no software tools capable of combining hydrodynamic modelling and health risk analyses, and the links between urban flooding and the health risk for the population due to direct contact with the flood water are poorly understood. The present paper outlines a novel methodology for linking dynamic urban flood modelling with quantitative microbial risk assessment (QMRA). This provides a unique possibility for understanding the interaction between urban flooding and health risk caused by direct human contact with the flood water and hence gives an option for reducing the burden of disease in the population by use of intelligent urban flood risk management. The model linking urban flooding and health risk is applied to Dhaka City in Bangladesh, where waterborne diseases including cholera are endemic. The application to Dhaka City is supported by measurements of pathogens in the urban drainage system. The outcome of the application indicates that direct contact with polluted flood water is a plausible route of primary transmission of cholera and demonstrates the applicability and the potential for linking urban flood models with QMRA in order to identify interventions to reduce the burden of disease on the population in Dhaka City.

Flood vulnerability assessment in the mountain–plateau transition zone: a case study of Marginea village (Romania)

Abstract: The Sucevita catchment is affected by heavy rains, which produce annual floods with catastrophic effects. Among them, the material damages caused to the dwellings of Marginea village stand out. The present study examines the vulnerability of the population and buildings of a village situated in the eastern part of the Eastern Carpathians. By applying the multicriteria method, areas with high flood vulnerability were pointed out in the Sucevita catchment. Hydraulic modelling was carried out using the HEC-RAS software and revealed that 58 dwellings with high vulnerability will be affected in the case of a flood with an exceedance probability of 1% and 17 buildings in the case of a flood with an exceedance probability of 5%. By knowing the flood vulnerability zones, the appropriate measures can reduce the damages of a hydrological event. Moreover, the proper delimitation of the floodplain leads to adequate economic management and ensures the security of the population.

Coastal subsidence detected by Synthetic Aperture Radar interferometry and its effects coupled with future sea‐level rise: the case of the Sele Plain (Southern Italy)

Abstract: The amount of coastal subsidence on the Sele River coastal plain has been examined and measured with local vertical land movement data The vertical displacements, derived by satellite radar differential interferometry processing (Ps-InSAR), show that the analysed coastal sector is characterised by a south-eastward decrease of vertical subsidence rates These results have been coupled with sea-level rise (SLR) scenarios, in order to identify the most critical areas In general, the subsidence mostly affects areas where alluvial deposits are thicker, the back-dune areas and the Sele River mouth, all late Holocene in age Five local SLR scenarios allow identifying zones in the plain potentially prone to inundation and the shoreline retreat for the years 2065 and 2100 For these dates, 22% and 706% of the investigated area will have a topography lower than the estimated future sea level Moreover, results show that the extent of the areas potentially exposed to inundation and erosion increases moving from south to north

Influence of sewer network models on urban flood damage assessment based on coupled 1D/2D models

Abstract: One of the main steps in assessing flood risk in urbanised areas is the quantification of damage costs. Damage is often estimated based on depth-damage curves for which depth maps are obtained (ideally) from coupled flood models. While the comparative analysis of flood damage models has been extensively researched in the literature, the influence of the underlying sewer network model has not been investigated. In this study, a 2D locally inertial equations flood risk analysis model (GWM) is coupled with two stormwater models (SWMM, tested with three different configurations, and SIPSON). The assessment of the network performance is made through the total exchanged volume between the surface and stormwater system, the surcharged conduits and manholes, maximum overland inundation and costs using a stepped version of the multi-coloured manual depth-damage curves for continuous urban fabric. The models behave similarly; however, they do show differences in the head pressures, number of surcharged manholes and maximum depth in some locations. The case study results show that despite the good agreement in damage between the four configurations (≈6% maximum disagreement), some localised high differences in maximum depth observed [0.25 (m)] exist. It was also shown that SWMM needs to be calibrated in order to perform similarly to Preissmann slot models.

Flood risk assessment in art cities: the exemplary case of Florence (Italy)

Abstract: Flood risk assessment is a crucial step for flood risk management purposes, thus answering the requirements of the European Flood Directive 60/2007/EC (European Commission). In this work, a census data scale, which has been considered as a good compromise between spatial resolution and availability of open socio-economic data, is adopted for risk analysis. The damage categories included are structures, household contents and the most representative economic activities in the city of Florence (Italy). Moreover, since Florence is an important art city, a preliminary evaluation of risk to cultural heritage is carried out. Data from hydraulic simulations, historical reports of the devastating 1966 flood and the cultural heritage recognition sheets allow estimating and mapping the annual expected number of works of art lost in the absence of risk mitigation strategies.

Flooding and inundation collaborative mapping – use of the Crowdmap/Ushahidi platform in the city of Sao Paulo, Brazil

Abstract: The trend of using volunteered and collaborative data in the context of natural disasters has been increasing This fact, together with floods and inundations, which occur in the city of Sao Paulo, makes it possible to explore the volunteered and collaborative way of generating and transmitting geographic data dynamically This can be done by using technologies affordable to the population, such as the Internet, the global positioning system and other monitoring systems embedded in mobiles This article aims to present the proposal of a conceptual scheme for a dynamic and collaborative mapping system of flooding points, whose data source comes from people equipped with mobile devices that allow identify their locations The results correspond to the conceptual scheme of the system as well as the prototype ‘Flooding Points’ – a map available on the web showing the flooding points in the city, which were provided at the time of the event by ordinary people The prototype was developed by using the free and open source Crowdmap/Ushahidi platform The system was assessed by a questionnaire answered by the users, who gave their opinion about its feasibility, as well as the adjustments which must be made for the population's effective use It was found that the application of system for subjects of inundation and flooding is complex in relation for other types of events due to its temporal dynamics characteristics The results of the questionnaire, applied to evaluate the system, demonstrated the public utility of the application and the interest of the population for a dynamic system that enables the exchange of information on the problem of inundation and flooding in near real time in the city of Sao Paulo