A Global Assessment of Climate Change and Anthropogenic Effects on Changes in Streamflow

Identifying the impacts of climate change and human activities on streamflow changes is essential for understanding hydrological processes and sustainable water resource management. This study investigated the spatiotemporal changes of annual streamflow in global 2264 catchments during 1961–2014, and quantified the contributions of precipitation (P), potential evapotranspiration (Ep) and landscape parameter (n) to streamflow changes using Choudhury-Yang equation based on Budyko hypothesis. The results indicated that significant increasing trends (p < 0.05) in annual streamflow (16.65%) mainly showed in northeastern North America, northern Europe, and central-southern South America, while significant decreasing trends in annual streamflow (12.01%) mainly occurred in western North America, eastern South America, southern Australia, and southwestern China during 1961–2014, which were largely consistent with the pattern of annual P trends. In general, arid and semi-arid catchments in central-southwestern North America, eastern South America, southern Africa, and Australia exhibited greater streamflow elasticities than the relatively humid catchments across eastern and northwestern North America, southern South America, Europe, and southwestern China. The P, Ep, and n dominated streamflow changes in the 50.7%, 0.9%, and 48.4% (53.1%, 2.4%, and 44.5%) of total catchments during 1986–2000 (2001–2014), respectively. The parameter n in more catchments showed positive correlations with NDVI, forest loss, cropland area, and impervious surface, and that showed negative correlations with population density and nightlight index. This study provides meaningful insights into the attribution of streamflow changes to climate change and human activities across the globe.