Rosso et al. (2025) Drought hazard assessment across Sweden's diverse hydro-climatic regimes

Identification

• Journal: Natural hazards and earth system sciences
• Year: 2025
• Date: 2025-11-18
• Authors: Claudia Canedo Rosso, Lars Nyberg, Ilias Pechlivanidis
• DOI: 10.5194/nhess-25-4577-2025

Research Groups

• Centre for Societal Risk Research (CSR), University of Karlstad, Karlstad, Sweden
• Centre of Natural Hazards and Disaster Science (CNDS), Uppsala, Sweden
• Swedish Meteorological and Hydrological Institute (SMHI), Norrköping, Sweden

Short Summary

This study assesses meteorological, agricultural, and hydrological drought hazard across Sweden using multiple standardized indicators and hydrological model simulations. It reveals distinct regional drought patterns, with central-eastern and south-eastern Sweden experiencing increasing dry conditions, while northern and western Sweden show wetting trends.

Objective

• To understand how spatial and temporal hydro-climatic dynamics shape drought patterns across Sweden.
• To compare meteorological, agricultural, and hydrological drought conditions in characterizing short- and long-term dry periods.
• To identify which regions in Sweden exhibit increasing drought conditions.

Study Configuration

• Spatial Scale: Approximately 39,635 sub-catchments across Sweden, with an average resolution of 13 square kilometers (km²).
• Temporal Scale: Daily hydro-meteorological simulations from January 1975 to December 2021 (47 years), with drought indicators computed at 1, 3, 6, 12, and 24-month timescales.

Methodology and Data

• Models used: S-HYPE hydrological model, K-means clustering (for identifying drought-informed regimes), Mann–Kendall test (for trend analysis).
• Data sources: Daily precipitation, evapotranspiration, soil moisture (upper two layers), and streamflow simulations from the national S-HYPE hydrological model.
• Indicators: Standardized Precipitation Index (SPI), Standardized Precipitation and Evapotranspiration Index (SPEI), Standardized Soil Moisture Index (SSMI), and Standardized Streamflow Index (SSI).

Main Results

• Five distinct drought-informed regimes were identified across Sweden based on soil moisture anomaly, revealing clear north-south and east-west gradients in drought patterns.
• Dry periods occurred less frequently in north-western Sweden (Clusters A and B) but were more common and severe in south-western and south-eastern parts (Clusters C, D, and E), particularly during summer months.
• Droughts assessed using SPEI were more frequent than those based solely on SPI, highlighting the significant role of temperature and evapotranspiration in water deficit.
• The 1976 drought showed the highest severity across all meteorological, agricultural, and hydrological types, while the 2018 event exhibited the highest severity for soil moisture (SSMI), correlating with reported crop losses.
• Central-eastern and south-eastern Sweden exhibited an increasing frequency of dry periods and significant negative trends (drying conditions) for SPEI, SSMI, and SSI at annual and biennial timescales, and in autumn and spring.
• Northern and western Sweden showed significant positive trends (wetting conditions) for SPI, SPEI, SSMI, and SSI at annual and biennial timescales, and generally in winter and spring.
• Winter generally showed a widespread tendency towards wetter conditions across the entire country for all indicators.

Contributions

• Provides a comprehensive drought hazard assessment for Sweden by integrating climatological, agricultural, and hydrological perspectives across diverse hydro-climatic regimes.
• Enhances the understanding of regional drought variability and the interconnected factors driving drought conditions through the use of multiple standardized indicators and clustering analysis.
• Offers valuable insights for improving drought monitoring, early warning systems, and informing long-term planning and adaptation policies in water-dependent sectors such as agriculture, water management, energy, and forestry.
• Evaluates the performance and limitations of various standardized drought indicators, aiding decision-makers in selecting the most relevant metrics for specific monitoring and management needs.

Funding

• Centre of Natural Hazards and Disaster Science (CNDS)
• Centre for Societal Risk Research (CSR) at Karlstad University

Citation

@article{Rosso2025Drought,
  author = {Rosso, Claudia Canedo and Nyberg, Lars and Pechlivanidis, Ilias},
  title = {Drought hazard assessment across Sweden's diverse hydro-climatic regimes},
  journal = {Natural hazards and earth system sciences},
  year = {2025},
  doi = {10.5194/nhess-25-4577-2025},
  url = {https://doi.org/10.5194/nhess-25-4577-2025}
}