Close co-variation between soil moisture and runoff emerging from multi-catchment data across Europe

Area of Science:

• Hydrology
• Climate Science
• Environmental Monitoring

Background:

• Soil moisture is critical for land-climate and hydrological processes.
• Understanding large-scale, long-term hydro-climatic interactions is essential for water resource management.
• Previous studies have focused on localized soil moisture dynamics, necessitating broader investigations.

Purpose of the Study:

• To investigate the large-scale, long-term interactions between soil moisture and key hydro-climatic variables across Europe.
• To assess the robustness of these interactions across different European climate regions and datasets.
• To explore the potential of using runoff data as a proxy for soil moisture variability.

Main Methods:

• Analysis of monthly soil moisture, precipitation, evapotranspiration, runoff, and temperature data from 1378 European hydrological catchments (1980-2010).
• Examination of variable anomalies and extreme value co-occurrence across different climate regions.
• Validation using three alternative observational and re-analysis datasets to ensure robustness.

Main Results:

• Monthly soil moisture anomalies showed a strong positive correlation with runoff anomalies across all European climates and datasets.
• Extreme soil moisture events largely coincided with extreme runoff events.
• Correlations with precipitation, evapotranspiration, and temperature were generally weaker than with runoff.

Conclusions:

• Runoff data provides a reliable indicator for assessing large-scale soil moisture variability and changes.
• Long-term stream discharge monitoring offers a viable method for inferring soil moisture dynamics.
• The findings support a new approach for monitoring soil moisture at continental scales using hydrological data.