Identifying regional heatwaves, droughts, floods

The authors propose a streamlined framework to detect and map extreme events—specifically heatwaves, droughts, and floods—by selecting optimal environmental indicators and thresholds. Tested in Sweden using data from 1922–2021, the framework identified increasing occurrences of heatwaves and floods in large areas, while finding no significant trend for droughts. The study also identified compound hazard hotspots in northern Sweden, where drought-heatwave and drought-flood events are positively correlated between June and August.

• The framework utilizes specific climate indices to characterize hazard intensity, frequency, duration, co-occurrence, and dependence, including the Standardized Precipitation Index, Standardized Precipitation and Evapotranspiration Index (SPEI), Standardized Streamflow Index, heatwave indices (HWIS and HWIE), and the Daily Flood Index (DFI).
• Testing the framework in Sweden with daily data from 1922–2021 demonstrated that HWIS, SPEI12, and DFI are suitable indices for representing heatwaves, droughts, and floods, with AUC values exceeding 0.83.
• Analysis of Swedish data revealed an increase in the occurrence of heatwaves and floods across large areas, though no significant change trend was observed for droughts. Additionally, compound drought-heatwave and drought-flood events are positively correlated in northern Sweden from June to August, as indicated by a Likelihood Multiplication Factor (LMF) greater than 1.

APA

Stockholm Environment Institute (2024). Identifying regional heatwaves, droughts, floods. https://www.sei.org/publications/identifying-regional-heatwaves-droughts-floods/

Chicago

Stockholm Environment Institute. Identifying regional heatwaves, droughts, floods. 2024. https://www.sei.org/publications/identifying-regional-heatwaves-droughts-floods/.

Wikipedia

{{cite report |author=Stockholm Environment Institute |title=Identifying regional heatwaves, droughts, floods |date=11 September 2024 |url=https://www.sei.org/publications/identifying-regional-heatwaves-droughts-floods/ |access-date=17 August 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{stockholmenvironmentinstitute2024identifying, author = {{Stockholm Environment Institute}}, title = {{Identifying regional heatwaves, droughts, floods}}, institution = {Stockholm Environment Institute}, year = {2024}, month = sep, url = {https://www.sei.org/publications/identifying-regional-heatwaves-droughts-floods/}, urldate = {2026-08-17}, note = {Indexed by Climate Insights Directory} }