Trends in streamflow, evapotranspiration, and groundwater storage across the Amazon Basin linked to changing precipitation and land cover

Abstract

Study region: The study region is the Amazon River Basin, which controls globally important water and energy fluxes. Study focus: In the face of a changing climate and landscape, it is critical that we understand how, where, and why surface water resources are changing. Specifically, we must consider holistic changes to the water cycle to understand how water resources are affected by climate change and landscape alterations. In this study, we investigate changes to all major components of the water balance across the entire Amazon Basin. We seek to understand: 1) how changes to land cover and precipitation affect streamflow, 2) how these factors affect evapotranspiration and groundwater storage water balance components, and 3) how changes to the water balance partitioning may in turn alter streamflows. New hydrological insights: We find significant changes to streamflow of ±9.5 mm/yr on average across the Amazon Basin. Streamflow alterations show a spatially variable pattern, with increasing discharge in the northern and western portions of the basin, and decreasing discharge in the southern and eastern basin. We also observe significant changes in evapotranspiration of ±29 mm/yr and groundwater storage increases of 7.1 mm/yr. Together, these results indicate that studies of streamflow change in the Amazon should consider changes to the whole water budget, including understudied aspects of groundwater storage across the Basin.

Keywords

• Groundwater storage
• Evapotranspiration
• Amazon River
• Streamflow
• Climate change
• Deforestation