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Hydropower dams have received increased global attention due to their detrimental socioenvironmental ramifications. Such attention has led to an increase in studies on the impacts of reservoir operation on river flow; however, a holistic understanding of the compounded effects of hydropower dams on different hydrological characteristics is lacking, especially for large river basins such as the Amazon where hydropower development is on the rise. Here, we mechanistically quantify the historical impacts of existing dams and the potential impacts of the collective operation of existing and planned dams on a basin‐wide scale in the Amazon for the 1981–2019 period. We build on the recently developed high‐resolution (3‐arcmin; ∼5 km) river‐floodplain‐reservoir model, the CaMa‐Flood‐Dam, which is enhanced to realistically simulate hydropower dam operation considering maximized power production. Flood simulations are further downscaled to 3 arc‐seconds (∼90 m) resolution to investigate the impacts of dams on fine‐scale flood dynamics across the basin. Results indicate that existing dams have substantially altered downstream river flow and flooding patterns across the Amazon River basin. Specifically, large dams in the Amazonian subbasins, including the Xingu, Madeira, and Tocantins, have altered downstream river flow amplitude by up to 3 orders of magnitude. Further, the collective operation of existing and planned dams could increasingly alter river flow patterns, causing ∼10% decrease in flood duration in many parts of the Amazon mainstem. Our results provide quantitative evidence on the severity of the hydrologic impacts of large hydropower dams and have important implications for sustainable hydropower operation and development in the Amazon and worldwide.

 

While there have been efforts to supply off-grid energy in the Amazon, these attempts have focused on low upfront costs and deployment rates. These “get-energy-quick” methods have almost solely adopted diesel generators, ignoring the environmental and social risks associated with the known noise and pollution of combustion engines. Alternatively, it is recommended, herein, to supply off-grid needs with renewable, distributed microgrids comprised of photovoltaics (PV) and in-stream generators (ISG). Utilization of a hybrid combination of renewable generators can provide an energetically, environmentally, and financially feasible alternative to typical electrification methods, depending on available solar irradiation and riverine characteristics, that with community engagement allows for a participatory codesign process that takes into consideration people’s needs. A convergent solution development framework that includes designers—a team of social scientists, engineers, and communication specialists—and communities as well as the local industry is examined here, by which the future negative impacts at the human–machine–environment nexus can be minimized by iterative, continuous interaction between these key actors.

 

Abstract. We investigate the interannual and interdecadalhydrological changes in the Amazon River basin and its sub-basins duringthe 1980–2015 period using GRACE satellite data and a physically based, 2 kmgrid continental-scale hydrological model (LEAF-Hydro-Flood) that includes aprognostic groundwater scheme and accounts for the effects of land use–landcover (LULC) change. The analyses focus on the dominant mechanisms thatmodulate terrestrial water storage (TWS) variations and droughts. We findthat (1) the model simulates the basin-averaged TWS variations remarkablywell; however, disagreements are observed in spatial patterns of temporaltrends, especially for the post-2008 period. (2) The 2010s is the driestperiod since 1980, characterized by a major shift in the decadal mean comparedto the 2000s caused by increased drought frequency. (3) Long-term trends in TWSsuggest that the Amazon overall is getting wetter (1.13 mm yr−1), but itssouthern and southeastern sub-basins are undergoing significant negative TWSchanges, caused primarily by intensified LULC changes. (4) Increasingdivergence between dry-season total water deficit and TWS release suggests astrengthening dry season, especially in the southern and southeasternsub-basins. (5) The sub-surface storage regulates the propagation ofmeteorological droughts into hydrological droughts by strongly modulatingTWS release with respect to its storage preceding the drought condition. Oursimulations provide crucial insight into the importance of sub-surface storagein alleviating surface water deficit across Amazon and open pathways forimproving prediction and mitigation of extreme droughts under changingclimate and increasing hydrologic alterations due to human activities (e.g.,LULC change).