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Flood

Flood presents a growing and complex risk for insurers and civil authorities throughout the world. Modelling flood hazard and risk presents significant challenges caused by the extensive range of factors contributing to flood events of given magnitudes at any given location at any particular time. The development of flood modelling and risk management solutions is an important focus for WRN members.

Insurers and civil authorities are required to evaluate and manage flood risk at various spatial and temporal scales and the WRN flood programme is unique in envisaging an integrated modelling continuum from local to global analysis incorporating hazard, exposure, vulnerability and loss. Only the breadth of WRN membership and integration around shared platforms and processes has enabled this comprehensive response to flood risk.

Global Flood Risk Modelling.

The WRN has developed mapping and analysis tools to provide comprehensive and consistent analysis of global flood risk for portfolios and populations. Using state-of-the-art analysis methods and collaborating with wider global flood modelling  efforts across science enables the WRN to develop scale-appropriate assessments of hazard and risk. The trade-off for comprehensive global coverage is coarseness of spatial resolutions, but the WRN modelling platform will evolve as further data and research become available enhancing these capabilities.

Regional and National Flood Risk Modelling.

The traditional scale of flood risk modelling for insurance companies has been at national and regional scales, corresponding with national insurance markets, data availability and existing platform capabilities. The WRN has an extensive regional flood risk modelling programme to meet current industry requirements, confronting new challenges such as supply chain risk and informing the WRN's global flood modelling programme

Urban Flood Risk Modelling.

Flood risk exposures are concentrated in major cities worldwide, many within exposed coastal and riverine locations. The WRN has pioneered the development of a range of techniques to provide insurers and urban authorities with flood models, mapping and decision support tools to manage flood risk at a city level. These models also inform the WRN's regional and global modelling programme.

Event Forecasting & Response.

The WRN has pioneered the use of forecasting, satellite imagery and other remote sensing techniques to help communities and insurers prepare for and manage the consequences of flood events. New satellite platforms and services in development with WRN partners offer significant advances in pre-, during- and post-event flood risk management.

Flood Modeling Technical Research.

Improved flood risk modelling across spatial and temporal scales depends upon advances in science, data, computation and visualisation. The strength of the WRN flood programme is driven by member institutions' commitment to fundamental research to gain greater understanding of pluvial, riverine, storm surge and groundwater hazard and how they combine with landscape and exposure to create flood risk and losses. This work underpins the Network's tools and risk management solutions.

Latest on Flood

  • Groundwater fluxes in a shallow seasonal wetland pond: The effect of bathymetric uncertainty on predicted water and solute balances

    Date: Jul 22, 2014 | Type: Paper | Attachment: Download File ›
    Journal: Journal of Hydrology | Ext. Link: Click Here ›

    Pillar: Natural Hazard & Risk
    Hub: Flood

    Authors: Mark A. Trigg, Peter G. Cook, Philip Brunner
    Fields:

    Summary: The successful management of groundwater dependent shallow seasonal wetlands requires a sound understanding of groundwater fluxes. However, such fluxes are hard to quantify. Water volume and solute mass balance models can be used in order to derive an estimate of groundwater fluxes within such systems. This approach is particularly attractive, as it can be undertaken using measurable environmental variables, such as; rainfall, evaporation, pond level and salinity. Groundwater fluxes estimated from such an approach are subject to uncertainty in the measured variables as well as in the process representation and in parameters within the model. However, the shallow nature of seasonal wetland ponds means water volume and surface area can change rapidly and non-linearly with depth, requiring an accurate representation of the wetland pond bathymetry. Unfortunately, detailed bathymetry is rarely available and simplifying assumptions regarding the bathymetry have to be made. However, the implications of these assumptions are typically not quantified.

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    The impact of uncertain precipitation data on insurance loss estimates using a flood catastrophe model

    Date: Jun 23, 2014 | Type: Paper | Attachment: Download File ›
    Journal: NatureHydrology and Earth System Sciences | Ext. Link: Click Here ›

    Pillar: Natural Hazard & Risk
    Hub: Flood

    Authors: C. C. Sampson, T. J. Fewtrell, F. O’Loughlin, F. Pappenberger, P. B. Bates, J. E. Freer, and H. L. Cloke
    Fields: Climate Change, Atmospheric science

    Summary: Catastrophe risk models used by the insurance industry are likely subject to significant uncertainty, but due to their proprietary nature and strict licensing conditions they are not available for experimentation. In addition, even if such experiments were conducted, these would not be repeatable by other researchers because commercial confidentiality issues prevent the details of proprietary catastrophe model structures from being described in public domain documents. However, such experimentation is urgently required to improve decision making in both insurance and reinsurance markets.

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    Development of the Global Width Database for Large Rivers

    Date: Apr 28, 2014 | Type: Paper | Attachment: Download File ›
    Journal: Water Resources Research | Ext. Link: Click Here ›

    Pillar: Natural Hazard & Risk
    Hub: Flood

    Authors: Dai Yamazaki, Fiachra O’Loughlin, Mark A. Trigg, Zachary F. Miller, Tamlin M. Pavelsky, and Paul D. Bates
    Fields:

    Summary: River width is a fundamental parameter of river hydrodynamic simulations, but no global-scale river width database based on observed water bodies has yet been developed. Here we present a new algorithm that automatically calculates river width from satellite-based water masks and flow direction maps.

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    Technology: Fight floods on a global scale

    Date: Mar 13, 2014 | Type: Paper | Journal: Nature | Ext. Link: Click Here ›

    Pillar: Natural Hazard & Risk
    Hub: Flood

    Authors: Guy J.-P. Schumann, Paul D. Bates, Jeffrey C. Neal & Konstantinos M. Andreadis
    Fields:

    Summary: Bristol and NASA issue call for international co-operation on global-scale flood model

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    Estimating seepage flux from ephemeral stream channels using surface water and groundwater level data

    Date: Feb 22, 2014 | Type: Paper | Attachment: Download File ›
    Journal: Water Resources Research | Ext. Link: Click Here ›

    Pillar: Natural Hazard & Risk
    Hub: Flood

    Authors: Saskia L. Noorduijn, Margaret Shanafield, Mark A. Trigg, Glenn A. Harrington, Peter G. Cook and L. Peeters
    Fields:

    Summary: Seepage flux from ephemeral streams can be an important component of the water balance in arid and semiarid regions. An emerging technique for quantifying this flux involves the measurement and simulation of a flood wave as it moves along an initially dry channel.

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    Spatial and temporal modeling of radar rainfall uncertainties

    Date: Jan 01, 2014 | Type: Paper | Journal: Atmospheric Research | Ext. Link: Click Here ›

    Pillar: Natural Hazard & Risk
    Hub: Flood

    Authors: Gabriele Villarini, Bong-Chul Seo, Francesco Serinaldi, Witold F. Krajewskia
    Fields: Weather radar; Rainfall; Uncertainty; Space–time modeling; NEXRAD

    Summary: It is widely acknowledged that radar-based estimates of rainfall are affected by uncertainties (e.g., mis-calibration, beam blockage, anomalous propagation, and ground clutter) which are both systematic and random in nature. Improving the characterization of these errors would yield better understanding and interpretations of results from studies in which these estimates are used as inputs (e.g., hydrologic modeling) or initial conditions (e.g., rainfall forecasting).

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    Rainfall extremes: Toward reconciliation after the battle of distributions

    Date: Dec 23, 2013 | Type: Paper | Journal: Water Resources Research | Ext. Link: Click Here ›

    Pillar: Natural Hazard & Risk
    Hub: Flood

    Authors: Francesco Serinaldi, Chris G. Kilsby
    Fields: extreme events;precipitation;time series analysis;peak-over-threshold analysis;heavy tail behavior

    Summary: This study attempts to reconcile the conflicting results reported in the literature concerning the behavior of peak-over-threshold (POT) daily rainfall extremes and their distribution.

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    Surface water connectivity dynamics of a large scale extreme flood

    Date: Nov 15, 2013 | Type: Paper | Journal: Journal of Hydrology | Ext. Link: Click Here ›

    Pillar: Natural Hazard & Risk
    Hub: Flood

    Authors: Mark A. Trigg, Katerina Michaelides, Jeffrey C. Neal, Paul D. Bates
    Fields: Geostatistical connectivity; Floodplain dynamics; 2011 Bangkok; Thailand; MODIS

    Summary: •Uses the MODIS surface water product observations of the 2011 Bangkok flood. •A data gap filling method is developed to better preserve the dynamics of the event. •We quantify surface water connectivity geostatistically to give new flood insights. •There is a clear structure to the connectivity of the event through time and space. •Changes and thresholds in the connectivity are linked to major flood mechanisms.

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    On the relationship between the index of dispersion and Allan factor and their power for testing the Poisson assumption

    Date: Oct 10, 2013 | Type: Paper | Journal: Stochastic Environmental Research and Risk Assessment | Ext. Link: Click Here ›

    Pillar: Natural Hazard & Risk
    Hub: Flood

    Authors: Francesco Serinaldi
    Fields: Index of dispersion Allan factor Power analysis Monte Carlo simulation Poisson process Point processes

    Summary: Several statistical tests are available for testing the Poisson hypothesis and/or the equidispersion of a point process. The capability to discriminate between the Poissonian behaviour and more complex processes is fundamental in many areas of research including earthquake analysis, hydrology, ecology, biology, signal analysis and sociology.

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    An uncertain journey around the tails of multivariate hydrological distributions

    Date: Sep 12, 2013 | Type: Presentation | Attachment: Download File ›
    Journal: Water Resources Journal | Ext. Link: Click Here ›

    Pillar: Natural Hazard & Risk
    Hub: Flood

    Authors: Francesco Serinaldi
    Fields: multivariate frequency analysis;copulas;Monte Carlo simulation;multivariate design events;Joint confidence intervals;uncertainty

    Summary: Moving from univariate to multivariate frequency analysis, this study extends the Klemeš' critique of the widespread belief that the increasingly refined mathematical structures of probability functions increase the accuracy and credibility of the extrapolated upper tails of the fitted distribution models.

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    SRTM vegetation removal and hydrodynamic modeling accuracy

    Date: Sep 04, 2013 | Type: Paper | Journal: Water Resources Research | Ext. Link: Click Here ›

    Pillar: Natural Hazard & Risk
    Hub: Flood

    Authors: Calum A. Baugh, Paul D. Bates, Guy Schumann, Mark A. Trigg
    Fields: SRTM DEM accuracy;global vegetation height data set;remote sensing;hydrodynamic modeling;Amazon River

    Summary: Hydrodynamic modeling of large remote forested floodplains, such as the Amazon, is hindered by the vegetation signal contained within Digital Elevation Models (DEMs) such as the Shuttle Radar Topography Mission (SRTM). Not removing the vegetation signal causes DEMs to be overelevated preventing the correct simulation of overbank inundation. Previous efforts to remove this vegetation signal have either not accounted for its spatial variability or relied upon single assumed error values. As a possible solution, a systematic approach to removing the vegetation signal which accounts for spatial variability using recently published estimates of global vegetation heights is proposed. The proposed approach is applied to a well-studied reach of the Amazon floodplain where previous hydrodynamic model applications were affected by the SRTM vegetation signal.

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    Hydraulic characterization of the middle reach of the Congo River

    Date: Aug 26, 2013 | Type: Article | Journal: Water Resources Research | Ext. Link: Click Here ›

    Pillar: Natural Hazard & Risk
    Hub: Flood

    Authors: F. O'Loughlin, M. A. Trigg, G. J.-P. Schumann, P. D. Bates
    Fields: Congo River;river characteristics;water surface slopes;backwater effects;river hydraulics

    Summary: The middle reach of the Congo remains one of the most difficult places to access, with ongoing conflicts and a lack of infrastructure. This has resulted in the Congo being perhaps the least understood large river hydraulically, particularly compared to the Amazon, Nile, or Mississippi. Globally the Congo River is important; it is the largest river in Africa and the basin contains some of the largest areas of tropical forests and wetlands in the world, which are important to both the global carbon and methane cycles. This study produced the first detailed hydraulic characterization of the middle reach, utilizing mostly remotely sensed data sets.

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    2013 Elbe and Danube Floods in Germany, Austria and Central and Eastern Europe

    Date: Jul 12, 2013 | Type: Industry Briefing | Attachment: Download File ›

    Pillar: Natural Hazard & Risk
    Hub: Flood

    Authors: Dr Tim Fewtrell, Giorgis Hadzilacos, Dr Angelika Werner, Thomas Kiessling
    Fields: Flood

    Summary: Willis’ post-event field damage survey report

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    The intrinsic dependence structure of peak, volume, duration, and average intensity of hyetographs and hydrographs

    Date: Jun 17, 2013 | Type: Article | Journal: Water Resources Research | Ext. Link: Click Here ›

    Pillar: Natural Hazard & Risk
    Hub: Flood

    Authors: Francesco Serinaldi, Chris Kilsby
    Fields: hydrographs;hyetographs;dependence structures;copulas;bootstrap;multivariate distributions

    Summary: The information contained in hyetographs and hydrographs is often synthesized by using key properties such as the peak or maximum value Xp, volume V, duration D, and average intensity I. These variables play a fundamental role in hydrologic engineering as they are used, for instance, to define design hyetographs and hydrographs as well as to model and simulate the rainfall andstreamflow processes.

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    Analysis of time variation of rainfall in transnational basins in Iberia: abrupt changes or trends?

    Date: Mar 11, 2013 | Type: Paper | Journal: International Jornal of Climatology | Ext. Link: Click Here ›

    Pillar: Natural Hazard & Risk
    Hub: Flood

    Authors: Selma B. Guerreiro,Chris G. Kilsby, Francesco Serinaldi
    Fields: rainfall;Douro;Tagus;Guadiana;transnational basins;change points;trends;field significance

    Summary: An analysis of recent-past changes in rainfall records from the three major transnational basins in Iberia was performed, using data from Spain and Portugal which are generally considered separately

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    On the sampling distribution of Allan factor estimator for a homogeneous Poisson process and its use to test inhomogeneities at multiple scales

    Date: Mar 01, 2013 | Type: Paper | Journal: Physica A | Ext. Link: Click Here ›

    Pillar: Natural Hazard & Risk
    Hub: Flood

    Authors: Francesco Serinaldi, Chris G. Kilsby
    Fields:

    Summary: The Allan factor (AF) is a statistic widely used to assess if the rate of occurrences of an event tends to cluster and show persistence in a range of space and/or time scales. This study investigates the sampling distribution function of the AF estimator when the underlying process is homogeneous Poissonian.

    Hurricane Sandy’s Storm Surge and the National Flood Insurance Program

    Date: Nov 30, 2012 | Type: Article | Attachment: Download File ›

    Pillar: Natural Hazard & Risk
    Hub: Flood

    Authors: Erwann Michel-Kerjan & Carolyn Kousky
    Fields:

    Summary: Flood Insurance Coverage in New York and New Jersey

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    Floodplain channel morphology and networks of the middle Amazon River

    Date: Oct 06, 2012 | Type: Paper | Journal: Water Resources Research | Ext. Link: Click Here ›

    Pillar: Natural Hazard & Risk
    Hub: Flood

    Authors: Mark A. Trigg, Paul D. Bates, Matthew D. Wilson, Guy Schumann, Calum Baugh
    Fields: Amazon River;bathymetric survey;floodplain channels;floodplain hydrologic units;hydraulic connectivity;várzea wetland

    Summary: Floodplain channels are important components of river-floodplain systems and are known to play a key role in hydrodynamic exchange and sediment transport. The Amazon floodplain exhibits complex networks of these channels, and despite their potential importance to this globally important wetland system, these floodplain channels are relatively unstudied. The research presented here is the first systematic and detailed study of the network and morphologic characteristics of a large number of these channels in the middle reach of the central Amazon River using analysis of data derived from Landsat Enhanced Thematic Mapper Plus (ETM+) mosaic and field survey.

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    Wharton Flood Report Briefing

    Date: Oct 04, 2012 | Type: Article | Attachment: Download File ›

    Pillar: Natural Hazard & Risk
    Hub: Flood

    Authors: Jeffrey Czajkowski & Vaughn Jensen
    Fields:

    Summary: Assessing the Feasibility of U.S. Private Market Flood Insurance - a study by WRN partner Wharton Risk Management and Decision Processes Center.

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    A modular class of multisite monthly rainfall generators for water resource management and impact studies

    Date: Sep 25, 2012 | Type: Article | Journal: Journal of Hydrology | Ext. Link: Click Here ›

    Pillar: Natural Hazard & Risk
    Hub: Flood

    Authors: Francesco Serinaldi, Chris G. Kilsby
    Fields: Flood

    Summary: This study introduces a class of stochastic multisite monthly rainfall generators devised for application in water resources management problems, such as the sensitivity analysis of droughts and extreme rainfall scenarios under external climatic and non climatic forcing mechanisms.

    Read More about this publication ›

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As economic, social and environmental uncertainties increase, institutions and populations seek greater resilience to support sustainable growth. Science and insurance lay at the heart of understanding, managing and sharing these risks, building more secure futures at local and global scales.

The Willis Research Network (WRN) operates across the full spectrum of risk from natural catastrophe, to legal liability, financial and security issues linked across driving themes: Resilience, Security & Sustainable Growth; Managing Extremes; Insurance & Risk Management and Mastering the Modelled World.

All Members and activities are united by a common aim: improving resilience by integrating first class science into operational and financial decision-making across public and private institutions.

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  • The WRN was formed in September 2006 to support leading academic research into extreme events, with a specific focus on responding to the challenges faced by businesses, insurers and governments
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