Delft-FIAT

A flexible damage model to support adaptation planning

Why damage modeling?

Floods are the costliest natural disasters, and as sea levels rise, storm frequencies increase, populations and the economy grow, the risk of flooding is increasing. Many communities are actively engaged in preparing for a flood-resilient future. This preparation requires an understanding of the current vulnerability and risk, how that vulnerability and risk are changing as we move into the future, and how interventions will reduce that risk over time.

Decision-makers have tough choices to make. Which interventions should they invest in, and when? How long will those interventions keep a certain level of service for the community? Which intervention should have priority? Are interventions impacting different sectors of the community equitably?

Flood and damage modeling provide information to decision makers that can help them prioritize and plan interventions. Flood modeling provides information on how certain events will cause flooding in the community, now, in the future, and with or without interventions like levees, sea walls, or drainage pumps. Damage modeling translates flooding into economic costs to buildings and roads, making it clearer which interventions reduce the costs most effectively.

Damage models make it possible to evaluate the effectiveness of measures in terms of the reduction in expected damages. Here you see a flood extent and damages without any adaptation measures implemented.

With the installation of a drainage pump, the flood extent is reduced. Many buildings that were flooded, are no longer flooded with this intervention in place. Consequently, the economic cost is greatly reduced.

What makes Delft-FIAT special?

At the core, most damage models are doing the same thing. They are evaluating the water depth at a building (or in some cases in a raster cell), and using vulnerability curves called depth-damage curves to translate that water depth into a fraction of total damage to the building.

Translating water depth to damages is the basis of most damage models

Fast and automated

What makes Delft-FIAT special is that it is fast and can be automated. It can be run many times using a script or a custom-built user-interface. This allows for hundreds - even thousands - of automatic damage calculations. Why so many?

Future risk. To really understand flood risk, and how it is changing, we need to consider how risk is affected by changing drivers - sea level rise, more frequent storms, more frequent rainfall events, increasing population and increasing economy. This means calculating the damages under these changing conditions.

Effectiveness of interventions. We also want to understand how flood risk is reduced by different interventions. That means assessing flood damages - now and under changing conditions - for a variety of interventions, like drainage system improvements, levees, sea walls, drainage pumps, home elevations, or floodproofing. And not just each intervention individually, we want to look towards the future. Maybe today we implement a drainage pump, and then in a few years start to elevate at-risk homes. That means we need to calculate the damages for combinations of interventions.

Damage models help us evaluate the effectiveness of interventions

A numbers game. Let's take an example. Suppose we have 10 potential interventions. We want to consider four sea levels. And we want to consider three future population projections. Let's say we have - for each intervention and future - five return period flood maps. The 5-year, 10-year, 25-year, 50-year, and 100-year. To calculate the risk for each combination of future and intervention, we are looking at 10 x 4 x 3 x 5 = 600 damage calculations. For many damage models, that is too labor intensive. Delft-FIAT can simply be called in batch mode to iterate over all the requested scenarios. So set it to run, and a few hours later your results are ready.

Flexible

"What doesn't bend breaks" - Ani DiFranco

Delft-FIAT has a flexible architecture. What does that mean? It means that a user is free to use the software in different ways without needing to make any changes to the code. For example, a user may want to try out different depth-damage functions, or include a different class of damage than the traditional structure and content damages. Delft-FIAT allows for this. Road damage, road outages, business interruption - these can all be included. Essentially any damage type that can be described with a depth-damage function can be analyzed in Delft-FIAT. Exposure data can easily be modified, and hazard data - the flood maps - can come from any source.

Delft-FIAT is also customizable. It can be connected to any user-interface to make a custom damage modelling tool for less-technical users. It can be connected to many different viewers, to custom-design the look and feel of the damage and risk output. This can be custom-designed viewers, or existing tools like PowerBI or ArcGIS Online. Delft-FIAT can be connected with other software, like flood-modeling software. Or built into an operational forecasting system.

Delft-FIAT can be combined with tailored scripts to answer tailored questions. For example, what is the impact of uncertainty in the finished-floor elevation of the buildings? What is the effect of uncertainty in the damage functions? These are serious questions because these are two of the biggest sources of uncertainty in flood damage estimates. By running Delft-FIAT multiple time with well-selected input, the user can do a sensitivity analysis, or even integrate the uncertainty in these inputs into the damage estimate. Another example is estimating tipping points - the point in the future when an adaptation intervention is no longer meeting levels of service. By running Delft-FIAT over future conditions, these tipping points can be derived. A user can even select which metrics are of interest in determining levels of service, such as: expected annual damage, number of flood houses in the 10-year flood event, or affected houses with income below the poverty level.

Where has Delft-FIAT been used?

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Department of Homeland Security: Community Flood-Resilience Support System

As part of a research partnership between the U.S. Department of Homeland Security (DHS) Science and Technology Directorate (S&T), Federal Emergency Management Agency (FEMA), Deltares USA, and the City of Charleston, SC, a community flood resilience support system (CFRSS) is being developed to provide adaptation planning support to communities which are vulnerable to compound flood hazards. The CFRSS will provide a quantitative tool to coastal communities with which to understand vulnerability and evaluate adaptation options. It comprises a fast compound flood model SFINCS , connected to the fast flood impact model Delft-FIAT. Through an intuitive user-interface, coastal communities will be able to calculate the flooding and flood impacts due to user-selected synthetic or historical hydro-meteorological events, climate and socio-economic projections, and adaptation strategies. The CFRSS will be developed in collaboration with and demonstrated in Charleston, SC.

Miami, Florida: Adaptive planning of flood mitigation options in the C-7 Basin

This pioneering project investigated adaptive strategies for sustained flood risk-reduction within the Little River Canal (C-7) Basin in Miami, Florida, considering future sea level rise. Three alternative adaptation strategies were assessed, including various structural and management measures, at different scales (local and regional). Delft-FIAT was used to calculate the economic damages and risk associated with each of the alternative strategies under increasing sea level rise. The effectiveness of each adaptation measure was then evaluated in terms of risk-reduction, cost and economic efficiency. Additionally, the measures were evaluated based on their adaptation tipping points, which indicate how long a measure will be effective in meeting levels of service. The tipping points are part of an adaptive planning approach, which was used to develop adaptation pathways. These pathways consist of sequences of measures which ensure risk targets are achieved in the short- and long-term. The timing of the transition between measures (within a pathway) depends on when an adaptation tipping point is reached (i.e. the point in time when risk targets are no longer met). These tipping points were analyzed for optimistic and pessimistic sea level rise scenarios. The methodology and findings were reported, to serve as input in the updating of the Miami-Dade Multi-hazard Local Mitigation Strategy.

Calcasieu Parish, Louisiana: Parish-wide adaptive stormwater management planning

Calcasieu Parish in Southwest Louisiana is susceptible to river and canal flooding, rainfall flooding, and flooding from storm surge. The Parish requested consulting and design services to proactively plan for adaptation in the face of uncertainties in climate change, socio-economic developments, and regional and state-wide flood protection initiatives. In a proactive move, the Parish chose for the innovative DAPP adaptive planning approach over more traditional static planning approaches.

The project team is applying the DAPP approach to create an adaptive strategic plan for investments over the 10 watersheds that make up Calcasieu Parish. The project involves collaboration between hydrodynamic surge and runoff modelers, engineers and design experts, vulnerability experts, damage modelers, adaptation planners and DAPP experts.

The project investigates the effectiveness of adaptation measures in ten watersheds, in terms of risk-reduction benefits, costs, and adaptation tipping points (the shelf-life of the measure), considering changes in subsidence, sea levels, precipitation frequencies, GDP growth, and urban development. For each watershed, adaptation pathways – which show sequences of measures over time – are developed to reach the Parish’s objectives and desired levels of service for a time horizon of 50 years. These are developed into an adaptive plan per watershed, with a master over-arching Parish-wide adaptive plan as the outcome of the project.

Broward County, Florida: Direct and cascading indirect damages

The need to reduce the indirect and cascading impacts of critical infrastructure (CI) disruptions during flood events is becoming increasingly urgent in flood risk management. While many communities understand the dependencies between CI, and the impact that disruptions have on other sectors, most of the information is qualitative.

This project developed a quantitative framework for the inclusion of cascading impacts in an economic risk analysis. This makes it possible to evaluate adaptation options focusing on CI resilience in terms of risk-reduction benefits.

The framework is being applied in Broward County to showcase a full economic risk analysis. This includes both cascading impacts from road network disruptions, calculated using the Deltares Criticality Tool, and direct damages from flooding, calculated using Delft-FIAT. The project team also analyzes the risk reduction due to two measures – one traditional approach, such as hazard reduction, and one that is focused on critical infrastructure resilience, such as road elevations or route redundancy.

South Florida: Evaluating the risk-reduction effectiveness of a drainage pump in the C-9 Basin

Delft-FIAT was used to quickly assess the risk-reduction effectiveness of a drainage pump in the C-9 basin, under current conditions and with future sea level rise and precipitation, to support a FEMA hazard mitigation grant application. The quick set-up and run-time of Delft-FIAT made it a feasible option for a quick turnaround time in the grant application process.

Resilient Caribbean: Sea level rise and adaptation potential in the Caribbean

Deltares and the World Bank, in collaboration with the Caribbean Disaster Emergency Management Agency are assessing the impacts of sea level rise resulting from an increase in coastal flooding and erosion in the region. The aim of the study is to derive proxies to estimate the resilient potential of each country in the region and their potential to adaptation. According to the project leader Alessio Giardino: “We are developing and applying an innovative modelling framework to be able to upscale the assessment to 17 countries. The assessment of impact and resilience potential of different countries in the region is going to provide interesting information on the relative vulnerability of each country to sea level rise and their options for adaptation”. The study is contributing to a World Bank flagship report to be published in 2021, which focuses on a holistic approach to resilience, with a specific focus on natural disasters and climate change in the Caribbean.

Marshall Islands: Coastal Vulnerability Assessment for Majuro Atoll

Multiple hazards and sea level rise threaten the livelihoods of nearly 30,000 people living on the Majuro atoll, as well as its natural resources and local ecosystems. The government of the Marshall Islands partnered with Deltares to carry out a multi-hazard risk assessment to evaluate current and future risks to the atoll, identify possible mitigation measures, conceptual designs and costing, and other related activities. State-of-the art models were used to assess flooding from multiple sources (swell waves, wind waves, storm surges, typhoons, tsunamis and rainfall), consequent risks and inform the conceptual design and evaluation of different options. Delft-FIAT provided the basis to compare costs and benefits between different options.

For more information:

https://www.deltares.nl/en/news/can-majuro-atoll-adapt-growing-risks-natural-hazards-sea-level-rise-new-study/

The Netherlands: National Flood Risk Model for the Dutch Delta Program

Development of the national flood damage model that was used to determine the protection levels in the Netherlands for the adaptive flood and water supply plans through 2100.

The Netherlands: Long Term Ambitions of the Primary Rivers

The Netherlands: Risk analysis for the Navy Harbor in Den Helder

The “Nieuwe Haven” in Den Helder, The Netherlands, is a port area where the Royal Netherlands Navy has concentrated most of its activities and possessions.

Deltares conducted a risk analysis for the Navy Port area. This included the implementation of a flood model which simulated the flood depths and flow velocities at the site during storms with extreme sea levels and waves. Delft-FIAT was then used to determine what damage is expected to occur to the buildings and key assets of the Royal Netherlands Navy. Due to the special nature of the area, the standard damage functions as used in other flood studies in the Netherlands were not applicable. Therefore, customized damages assessments were carried out and building- and asset-specific damage functions were derived and implemented in Delft-FIAT. Then, for all storm conditions, the damage was derived and combined into an expected annual damage due to flooding. This information was later used in and follow-up study to define measures to reduce flood damage.

The Netherlands: Climate Risk for Large Investors in Real Estate

Financial institutions must increasingly take into account the risks associated with climate change. In 2017, the Dutch National Bank started a study on the impact of climate risks on the Dutch financial sector.

Deltares contributed to the study by demonstrating the potential impact of a large flood event in the Netherlands. These impacts were estimated from flood simulations of various potential flood events at different locations in The Netherland (see Figure for one example flood simulation). Delft-FIAT was used to estimate direct and indirect damages. The results were used as input by financial experts to assess whether large financial institutions and investors (like insurance companies or pension funds) may run into financial problems that they cannot solve without intervention from the government or DNB.

Mozambique: Safe Hospitals

Computation of direct and indirect risk metrics to quantify economic damage and disruption of services in the health sector in Mozambique due to five different natural hazards: Coastal winds, coastal flooding, pluvial flooding, fluvial flooding and earthquakes. Identification of retrofitting options and computation of associated risk reduction.

Sao Tome and Principe: Multi-hazard and risk assessment of coastal communities

The combined effect of high exposure to natural hazards and lack of land use planning and enforcement of existing regulations, make the islands of São Tomé and Príncipe extremely vulnerable to the impacts of extreme events and climate change. Deltares and CDR International (sub-consultant) partnered together and worked in close cooperation with MOPIRNA (the Ministry of Public Works, Infrastructures, Natural Resources and Environment) and local communities to quantify hazards, risks and adaptation options at eight locations in São Tomé and Príncipe. The main natural hazards affecting the coastal communities are coastal flooding due to extreme storm surge and waves, river flooding, flash flooding and overland flows from intense rainfall, high winds, and beach loss. Climate change and sea level rise will exacerbate most of these hazards. The state-of-the-art numerical models Delft3D , XBeach and SFINCS were implemented in order to assess the various hazards and climate change scenarios and the effectiveness of possible adaptation measures. Hazards were translated into risks and damages to the local communities using Delft-FIAT. Local communities were involved throughout the study, following a participatory approach, in the assessment and validation of hazards and risks and in the definition of suitable adaptation options.

For more information:

https://www.deltares.nl/en/news/adaptation-climate-change-sao-tome-principe/

Liberia: Flood Risk Profile of Greater Monrovia Region

Monrovia faces multitude challenges affecting prosperity including threats posed by rain, river and coastal flooding, which may be exacerbated by future climate change, population growth and unplanned urban development. Deltares and iLab Liberia helped the World Bank define flood hazard and risk for the city through the creation of a flood model (SFINCS) and risk model (Delft-FIAT). Following consultations with key stakeholders to understand the flooding events and impact on local people, FIAT was employed to derive damage and risk across the city for the current and future situation. Accounting for future climate change (higher sea levels and rainfall) as well as increased population. The damage calculated by FIAT accounts for the diverse urban fabric within Monrovia including building types, materials and whether they are located in slums or formal areas. FIAT leverages the open street map database to create the risk profile.

Tanzania: Flood risk assessment and Scenario Dashboard

Tanzania’s economic and social growth is hampered by significant flooding problems. This is most pertinent in the fast growing urban areas of Dar es Salaam and Zanzibar City. Regular rain and river flooding cuts off parts of the cities, damaging property, disrupting transportation and threatening lives. This is not only a damage issue but prevents people accessing their place of work, prevents children reaching schools and increases risk of waterborne disease. The World Bank commissioned Deltares to quantify the flood hazard and risk through the creation of a flood model (Delft3D) and risk model (Delft-FIAT). Following consultations with key stakeholders to understand the flooding events and impact on local people, FIAT was employed to derive damage and risk across the two cities for the current and future situation. Accounting for future climate change (higher sea levels and rainfall) as well as increased population and economic growth. The damage calculated by FIAT accounts for the diverse urban fabric within the two cities including building types and materials. A probabilistic approach was employed to generate the full range of possible flood events to give the most complete picture of risk for the cities. FIAT leverages the extensive database of open data on the urban fabric developed under the World Bank’s Tanzania Urban Resilience Programme funded by United Kingdom’s Foreign, Commonwealth & Development Office.

Bangladesh Climate Adaptation

In this project, Delft-FIAT was used to analyze the current and future storm surge flood risk for five polders for which conceptual embankment designs will be made. The flood inundation model SFINCS was set up for each polder to estimate the extent of flooding under extreme surge levels and wave heights. For the preliminary risk analysis, FIAT-Accelerator was applied using global and local data and assessed mortality, loss of assets (housing), loss of agricultural crop revenues and interruption of economic production.

For each polder one impact model was set up with exposure maps and damage functions. The impact model used as input the inundation results corresponding to eight different scenarios: four return periods with sea level rise and subsidence and four return periods without.

The results of the FIAT calculations show that the embankments provide significant economic risk reduction, but that sea level rise and subsidence will lead to a drastic increase in risk. The embankments can only offset part of the increased risk, underpinning the importance of considering additional disaster risk reduction measures.

More information about the project can be found here: https://www.deltares.nl/en/news/new-study-improve-polder-management-bangladesh-2/

Sri Lanka: Protecting Colombo against future floods

Colombo, the capital of Sri Lanka, was hit in May 2016 by the worst flooding since 1989. Encroachment of valuable wetland systems, informal settlements and less efficient urban drainage systems contributed to the intensity of this flood. The micro drainage system experienced clogging and high backwater from the main canal system at their outfall locations. The Colombo Metrological Office recorded 256mm on May 15; approximately a 10 year return period storm event. The Kelani River, bordering the city center on the Northeast, reached the second highest discharge in thirty five years. Combined with neap tide this led to the most devastating flood in almost three decades. In Colombo district alone, 185.000 people were directly affected by the floods, with three reported deaths.

Deltares was asked to support the government of Sri Lanka in the “Metro Colombo Urban Development Project” with a comprehensive assessment of the risks of flooding and a strategy to reduce those risks.

The main objective of the project is two-fold: first, to assess the current and future flood risk in Colombo Metropolitan Region, and second, to develop a flood risk strategy in cooperation with targeted stakeholders in view of future land use scenarios. The project is executed by a consortium headed by Deltares, together with the Asian Disaster Preparedness Center (ADPC) and the Central Engineering Consultancy Bureau of Sri Lanka (CECB).

Probabilistic risk assessment

A detailed hydrodynamic model of the Metro Colombo region was used to execute a probabilistic analysis of the flood hazard. This is combined with an economic analysis of vital infrastructure, buildings of all types, and agricultural land use, in order to estimate the potential damage resulting from floods of various types and magnitude. Important goals in the project are strengthening of the local capacity for probabilistic risk assessments and mainstreaming risk information into urban development planning. During the project several dedicated trainings and workshops are organized.

Strategic interventions

The strategy will include flood risk reduction interventions such as improving the drainage systems, creating extra storages, enlarging the conveyance and outfall capacities as well improvement to flood early warning, formulation and implementation of necessary policies for land use management, building control, etc.

The results will be input to the City Development Strategy for the Colombo Metropolitan Region that is developed in 2017.

Indonesia: Identify flood risk for 25 cities

Deltares will be commissioned by the World Bank to map the long term flood risks for 25 cities in Indonesia, taking into account the expected urbanization and the consequences of climate change. The data and basic information will be made accessible through a database, so that other cities benefit from this research. For the five cities with the highest risk, Deltares will also provide advice on how these cities can structurally defend themselves against these natural disasters.

Deltares works together with the Asian Disaster Preparedness Center (ADPC) and PT Wiratman. The aim of the research is to increase information and awareness at national and urban level and to identify which measures are necessary and effective to reduce flood risks and prevent disasters. Policy makers can make better informed decisions based on the information from this research so that the city is safe and livable in the longer term.

With the support of the Indonesian Sustainable Urbanization Multi-Donor Trust Fund (IDSUN) and the Global Facility for Disaster Reduction and Recovery (GFDRR), the World Bank is supporting the government of Indonesia to improve the understanding of disasters and climate risks by developing sustainable solutions. This involves looking at physical measures like green infrastructure in the city, drainage and groundwater management but also at non-physical measures like improving warning systems and risk-controlled urban planning.

This research is of great social importance. On average, almost 1.3 million people face flooding each year. The government of Indonesia spends between 300-500 million euros each year on reconstruction after these disasters. Moreover, the country is very vulnerable to the effects of climate change, such as rising sea levels and changing weather patterns, which in turn can lead to increased uncertainty in the availability of water, food production, transportation disruptions and urban development. In addition, the country is rapidly urbanising. It is expected that in 2035 71% of the Indonesian population will live in cities. Investing in urban drainage, flood management and improved preparedness is therefore becoming increasingly important because more people are exposed to risks.

Philippines: Nature-based approaches for climate change and disaster risk management

The FIAT accelerator was used to estimate current and future flood risk and to evaluate different options in the Buayan river basin (Philippines). As we didn’t estimate the hydrological impact of the options, we did assumptions on the impact (e.g. protecting against 1/10 floods or full protection (when relocated)).

Uzbekistan: Tashkent...

Afghanistan: Multi-hazard Risk Analysis

The geographical location of Afghanistan and years of environmental degradation in the country have made Afghanistan highly prone to intense and recurring natural hazards such as flooding, earthquakes, snow avalanches, landslides and droughts. Since 1980, disasters caused by natural hazards have affected 9 million people and caused over 20,000 fatalities in Afghanistan.

The understanding and accessibility of hazard, exposure, vulnerability and risk information is key to the effective management of disaster risk. Currently, the government of Afghanistan possesses limited information about current and future disaster risks and the effectiveness of policy options as a basis for decisions about reconstruction and risk reduction.

The World Bank and Global Facility for Disaster Reduction and Recovery (GFDRR) initiated a project to develop new risk information for Afghanistan about fluvial floods, flash floods, droughts, landslides, snow avalanches and seismic hazards. The project was carried out by a consortium of five institutes: Deltares (Netherlands), ENEA (Italy), GRF-Davos (Switzerland), KIT-Karlsruhe (Germany) and OMRAN (Afghanistan). Deltares was responsible for the overall project lead and risk assessments for fluvial floods, flash floods and droughts.

Risk is computed as the product of hazard, exposure and vulnerability. The hazard component is the combination of probability and magnitude of hazardous events. Hazard analyses were carried out separately for each threat. Several models were implemented to simulate the relevant processes involved. These models were fed by climate data and geological data like elevation, slope, land use, soil characteristics and so on.

Exposure is a measure of the assets and population at risk. An extensive data collection and processing effort was carried out to derive nation-wide exposure data. This includes data about the population, residential buildings, household inventory, commercial buildings, schools, hospitals, mosques, capital stock and livestock. The derived exposure data were applied uniformly to all threats to ensure mutual consistency.

Vulnerability is a measure of potential exposure losses if a hazardous event occurs. Vulnerability analyses were carried out separately for each threat because of differences in the impact characteristics. For example, the vulnerability of agriculture to floods is high, whereas the vulnerability of agriculture to earthquakes is low.

The main project output consists of tables and maps (GIS) showing hazard, exposure and risk. The tables present results at the nationwide, province and district levels. An example of a flood hazard map and a risk map for the Nangarhar province can be found in the illustration. It shows the clear similarities between the hazard and risk contours. Areas of high risk (>500/y/ha) are found in municipality districts that are located in the floodplain as these are the areas where both hazard and exposure are significant. All maps are stored in an open access Web-based GIS platform (http://disasterrisk.af.geonode.org/), which can be consulted by the government of Afghanistan, the World Bank, NGOs or anyone else interested in risks due to natural hazards in Afghanistan.

Australia: Operational forecasting of flood impacts

During Tropical Cyclone Debbie, the Australian Bureau of Meteorology was confronted with a disparity between the magnitude of riverine flood forecasts and storm surge guidance at Mackay, which added complexity to the warning process. The model and data rich environment of Australia allows for a state-of-the-art operational inundation and flood impact modelling information system. So inspired by TC Debbie, the Bureau and Deltares have started a research project to set up a Proof of Concept (PoC) for an operational forecasting system that looks at the interactions of combined riverine and coastal inundation, as well as the following damage and impact.<

The PoC makes use of existing operational flood and coastal models, as operated by the ureau, combined with a inundation model and impact model developed newly by Deltares. The inundation model (DFLOW-FM) and uses riverine and coastal boundary conditions from the operational systems of the Bureau. The impact model (Delft-FIAT) is based on static data provided by Geoscience Australia to determine the impact of the forecast inundation. Both DFLOW-FM and Delft-FIAT are open source tools.

The PoC is a standalone system, with test data to run the centennial 1918 Tropical Cyclone in current-day Mackay. There are several research questions we try to answer with this project, but the ultimate question is how this forecast data can be used to provide better and timely information to end users like SES and councils.