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River flooding - Local areas

<p>This dataset provides estimates on the share of population exposed to river flooding in OECD Local Areas. </p>

<p> Population exposure to river flooding is assessed using a 100-year return period, which corresponds to the average duration between two flooding events of the same intensity. </p>

<p style="color: #0965c1; font-weight: bold;"> The data is organized at Territorial Level 2 (TL2). To visualize the data at Local Area level, click on the corresponding TL2 indicator. </p>

<b>The full dataset can be downloaded here: <a href="https://stats.oecd.org/wbos/fileview2.aspx?IDFile=dbddc178-9a8b-42ee-ba2c-3cec23ff4047">Download Microdata </a></b>

<h3>Data sources and methodology</h3> <p align="justify"> River flooding indicators are estimated using the River Flood Hazard Maps at European and Global Scales datasets <a href=https://doi.org/10.2905/1D128B6C-A4EE-4858-9E34-6210707F3C81>(Dottori, F. et al., 2021)</a>, which provide the extent of river floods for different return periods (10 to 100 years). A return period corresponds to the estimated time interval between floods of similar intensity. For OECD countries located in Europe and the Mediterranean Basin, the regional 250-metre resolution map was used. For the remaining OECD countries, the global map with a spatial granularity of 1 km was used. Built-up area exposure to river floods is computed by intersecting this map with Copernius annual land cover data <a href=https://doi.org/10.24381/cds.006f2c9a>(Copernicus Climate Change Service, Climate Data Store, 2019)</a> and population exposure is computed using the Global Human Settlement Population layer <a href=https://doi.org/10.2760/098587>(European Commission, GHSL Data Package 2023)</a>. Harmonised international hazard models are used to ensure global comparability, consistent modelling assumptions across countries, and complete subnational coverage. </p>

<p align="justify">These estimates may differ from official subnational flood risk statistics due to differences in methodological approaches - such as the use of global, modelled top down hazard maps versus national hydrological models or administrative flood zone delineations - as well as variations in input data sources, spatial resolution, and hydraulic modelling techniques. </p>

<h3>Further information</h3> <ul> <li> <a href=https://localdataportal.oecd.org/>OECD Local Data Portal </a> </li> <li> <a href=https://www.oecd.org/en/publications/oecd-regions-and-cities-at-a-glance-2024_f42db3bf-en.html/>OECD Regions and Cities at a Glance </a> </li> </ul> <p align="justify">For questions and/or comments, please email <a href="mailto:CitiesStat@oecd.org">CitiesStat@oecd.org</a>