Pluvial Hazard, Risk Assessment and Adaptation Tool

Objective(s)

The Pluvial Hazard, Risk Assessment and Adaptation Tool provides a quick assessment of pluvial flood risk hotspots and supports the prioritization of areas for adaptation solutions, focussed on nature-based approaches. The tool can assist cities in analysing risks and solutions under various scenarios and plan future actions according to their disaster risk reduction and climate adaptation goals.

Short description

The Pluvial Hazard, Risk Assessment and Adaptation Tool is designed to assess flooding associated with intense rainfall in urban settings (pluvial flooding) and estimate benefits associated through the implementation of disaster risk reduction and climate adaptation solutions. For example, nature-based solutions at the urban scale aimed at reducing economic building damage and population exposure. The tool can be used to assess the benefits of nature-based and traditional solutions based on local criteria and priorities, including walking distance to existing green spaces, green space and green roof conversion feasibility, and population vulnerabilities to prioritize areas to implement solutions.

Free keywords

Pluvial Flood, Urban Flood, Nature-based Solutions, Economic Damage, Disaster Risk Reduction

Readiness for use

Applications

The tool, since 2021, has been implemented as part of the REACHOUT Horizon 2020 project in four European cities: Athens (Greece), Gdynia (Poland), Logroño (Spain), and Milan (Italy).
Athens is using the tool to prioritize green conversion of impervious areas that have the additional co-benefit to increase the accessibility to green spaces while also reducing pluvial flood risk.
Gdynia has used the tool to identify pluvial flood risk hotspots and compare the benefits of both green and grey disaster risk reduction solutions.
Logroño is using the tool to identify pluvial flood risk hotspots and to assess planned and potential nature-based solutions such as green area conversion and bioswales under current climate and future climate change projections.
Milan is assessing green conversion and pervious pavement solutions with the pluvial flood tool to estimate economic damage reduction benefits across the city under the current climate and future climate scenarios.
The pluvial flood hazard module was applied in Rimini, Italy to assess the benefits of the adoption of nature-based solutions (NBS) in improving the seafront promenade. Scientific articles illustrate the tool and its implementation.

Strengths and weaknesses, comparative added value to other similar tools

Strenghts:
(+) The tool is highly customizable and can be applied with local priorities and a variety of data, including open and European scale (allowing comparability) or local data, including at a very detailed level (scale of meters, from minutes to hours).

Weaknesses:
(-) Customization often requires local knowledge and data pre-processing. The tool generally requires some knowledge of urban hydrology and computational skills for spatial and rainfall data processing, scenario development, and running of simulations (GIS and R and/or Python).
(-) The tool does not consider the time evolution of flooding nor the direct consideration of storm sewer systems.

Integration:
The tool can be well integrated with vulnerability assessment tools to assess and visualize risk and to support the identification and prioritisation of solution locations. The tool is connected to other tools and frameworks through the REACHOUT Triple-A toolkit. To assess the co-benefits of nature-based solutions, the Thermal Assessment Tool and the Social Vulnerability Tool in the REACHOUT Triple-A toolkit would be ideal candidates for integration. The model could also be integrated with fluvial and coastal flood hazard tools.

Input(s)

To estimate pluvial flood depth, the tool requires data to characterise the surface, including elevation, land use, and soil. Rainfall data are needed as input, which can include historical and climate change scenario data. To identify and optimize the areas for greening, land use data and regional and an understanding of local priorities are required. To estimate exposure and vulnerability, building information (area, type and cost), population data and often socioeconomic data are required.

The tool can use input data taken from standardised datasets including at the European and global scale (e.g., Copernicus datasets for land use and climate data, OpenStreetMap for building information, Eurostat for census and socioeconomic data). However, based on specific user goals and needs, all analyses can be customised using local input data.

Output(s)

The tool provides high-resolution maps of pluvial flood maximum water depths, maps of greening scenarios, economic building damage due to flooding, and populations exposed to flooding. Summary estimates of total economic damage for each building class (residential, commercial, industrial, etc) and total population exposed are provided over the area of interest for each scenario. These estimates provide a means to compare rainfall and adaptation scenarios.

Some additional visual examples and a detailed description of the outputs can be found here.

Replicability: Cost/effort for (new) usage

This tool is ready for use in any location in the world. Basic use of the tool requires little effort, on the order of 3 to 5 person-days. However, advanced use of the tool varies widely depending on the specific needs and level of analysis performed, including harmonisation and pre-processing of local data, statistical analyses of rainfall, processing of climate change scenarios, and selection of greening scenarios. Such an analysis can vary from approximately 10 person-days to several person-months.

The pluvial flood module has a fee for full-version use. Prices vary from 3 to 20 €/km² per year based on the required resolution.

Materials or other support available

A description of the tool is available at the REACHOUT portal https://reachout-cities.eu/triple-a-toolkit/. The pluvial flood hazard module is available at https://saferplaces.co, where a trial version is available and a demo (virtual session) can be booked. Supporting material for the green scenario identification and optimisation and the damage and population exposure modules are not yet available but support by the developers can be provided upon request.

Website and maintenance

A pluvial flood hazard module of the tool is available at the developer’s website https://saferplaces.co. The platform has a free trial but a fee is required for the full version (price varies with the resolution of analysis). The green scenario identification and optimisation and the damage and population exposure modules have not yet been made available online but are available upon request.

Contact

Jaroslav Mysiak
jaroslav.mysiak@cmcc.it
Euro-Mediterranean Center on Climate Change (CMCC) | Ca' Foscari University of Venice
Risk Assessment and Adaptation Strategies Division (RAAS)
Porta dell'Innovazione Building | 2nd Floor Via della Libertà, 12 | 30175 Venice (VE), Italy

Associated project(s)

REACHOUT: Funded by the European Union’s Horizon 2020 research and innovation programme under grant agreement No 101036599. https://reachout-cities.eu

SaferPlaces: Funded by CLIMATE KIC. https://saferplaces.co