Understanding how drought alters the connection between rainfall and river flow is critical for managing water resources in a changing climate. A new study led by Matanó et al. (2025) provides global insights into this dynamic, using advanced datasets and statistical models to reveal how drought severity and duration affect streamflow in diverse regions. In particular, the study combined long-term global datasets to capture drought characteristics and their impact in 5590 catchments around the world: precipitation (MSWEP), surface and root soil moisture (GLEAM), total water storage (GRACE), surface water extent (Landsat) and NDVI (STAR) datasets covering from 25 to 34 years in 1980-2016 period. These datasets allowed the authors to analyse the droughts, distinguishing among meteorological drought (precipitation deficit), soil moisture drought (prolonged soil moisture depletion), and NDVI anomalies (negative vegetation health), and assess their influence on streamflow.
To analyse the data, the authors used two approaches: (1) for catchments with stationary Q-P series, they applied mixed effects panel data model to quantify how droughts influence the Q-P ratio. (2) For catchments showing abrupt changes (e.g. sudden shift in streamflow), they used a trend and step-change detection analysis to identify when and how this shifts occurred.
The study revelas regional differences: droughts in arid and semi-arid regions sharply reduce streamflow responses, while snow-inlfuenced regions show greater resilience due to water-buffering mechanisms delaying the impact of drought. Moreover, longer and more severe droughts amplify the reduction in streamflow response. These results also highlight the need for region-specific drought management strategies at catchment scale - such as groundwater recharge in arid zones and snowpack monitoring in montainous regions.
For more detailed information, please refer to:
Matanó, A., Hamed, R., Brunner, M. I., Barendrecht, M. H., and Van Loon, A. F.: Drought decreases annual streamflow response to precipitation, especially in arid regions, Hydrol. Earth Syst. Sci., 29, 2749–2764, https://doi.org/10.5194/hess-29-2749-2025, 2025.
Photo credits: (C) Marek Poplawski, Orange River, Namibia and South Africa. Downloaded from AdobeStock.com