Appropriateness of the “100-year event” terminology for communicating flood risks: Swedish house owners' and practitioners' understanding of hydrological return periods
- 1Department of Computer and Geospatial Sciences, Faculty of Engineering and Sustainable Development, University of Gävle, Gävle, 801 76, Sweden; Gästrike Vatten AB, Hamnleden 20, Gävle, 806 41, Sweden; Corresponding author at: Department of Computer and Geospatial Sciences, University of Gävle, 801 76 Gävle, Sweden.
- 2Department of Computer and Geospatial Sciences, Faculty of Engineering and Sustainable Development, University of Gävle, Gävle, 801 76, Sweden
Abstract
Rainfalls with different recurrence intervals, such as the 100-year rainfall, are used by practitioners in stormwater or urban planning and to communicate flood risks to the public. For these statistical terms to be efficient, it is important that they are understood by the intended users, i.e., both practitioners and the public. Through three research questions, we examine the appropriateness of using the 100-year flood or rainfall event for communication of flood risk. The first question treats how flood risk terminology is understood. The second investigates how the perceived risk is affected by communication, and the third looks at what affects a person's understanding of flood risk terminology. Questionnaires were sent to practitioners at Swedish municipalities and house owners in five Swedish municipalities. Both groups showed varied understanding of hydrological return periods, with practitioners demonstrating a better understanding. Additionally, using different expressions to describe flood risk influenced perception, where longer time periods were associated with higher risk perception. Unlike previous studies, understanding of flood risk terminology was quantitatively evaluated, and the focus on house owners and practitioners also included pluvial flood risks. The study concludes that commonly used flood risk terminology is difficult to understand and that communication impacts risk perception.
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BibTeX
@article{frihammar2026appropriateness,
title = {{Appropriateness of the “100-year event” terminology for communicating flood risks: Swedish house owners' and practitioners' understanding of hydrological return periods}},
author = {Esmeralda Frihammar and S. Anders Brandt and Nancy Joy Lim},
journal = {Progress in Disaster Science},
year = {2026},
month = oct,
doi = {10.1016/j.pdisas.2026.100768},
url = {https://doi.org/10.1016/j.pdisas.2026.100768},
note = {CC BY},
}
RIS
TY - JOUR
TI - Appropriateness of the “100-year event” terminology for communicating flood risks: Swedish house owners' and practitioners' understanding of hydrological return periods
AU - Esmeralda Frihammar
AU - S. Anders Brandt
AU - Nancy Joy Lim
PY - 2026
DA - 2026/10/30
JO - Progress in Disaster Science
DO - 10.1016/j.pdisas.2026.100768
UR - https://doi.org/10.1016/j.pdisas.2026.100768
AB - Rainfalls with different recurrence intervals, such as the 100-year rainfall, are used by practitioners in stormwater or urban planning and to communicate flood risks to the public. For these statistical terms to be efficient, it is important that they are understood by the intended users, i.e., both practitioners and the public. Through three research questions, we examine the appropriateness of using the 100-year flood or rainfall event for communication of flood risk. The first question treats how flood risk terminology is understood. The second investigates how the perceived risk is affected by communication, and the third looks at what affects a person's understanding of flood risk terminology. Questionnaires were sent to practitioners at Swedish municipalities and house owners in five Swedish municipalities. Both groups showed varied understanding of hydrological return periods, with practitioners demonstrating a better understanding. Additionally, using different expressions to describe flood risk influenced perception, where longer time periods were associated with higher risk perception. Unlike previous studies, understanding of flood risk terminology was quantitatively evaluated, and the focus on house owners and practitioners also included pluvial flood risks. The study concludes that commonly used flood risk terminology is difficult to understand and that communication impacts risk perception.
SN - 2590-0617
ER -