Sediment Flows in South America Supported by Daily Hydrologic‐Hydrodynamic Modeling

Fan

et al. 2023

Preprint

Sediment flows dynamics (erosion, transport and deposition) have been disrupted in South America (SA), a continent with the highest erosion and sediment transport rates globally. However, the magnitude and spatial distribution of the main drivers of changes have been poorly identified and explored. Here, we performed simulations using a hydrological-hydrodynamic-sediment model to comprehensively estimate the spatial and temporal sediment changes and trends in SA from 1984 to 2019. We found that 51% of the main SA rivers experienced significant changes in simulated sediment transport (QST) over this period, with 36% due to Amazon deforestation and river damming and 15% due to precipitation changes. We also estimated a 10% reduction in the average sediment delivery to the oceans. Deforestation was responsible for QST changes above 80% in some Amazon sites, and hydropower expansion led to a greater reduction of sediment flows (as high as 80-100%) in the Tocantins, Uruguay, Upper Paraná, lower São Francisco, Desaguadero, and Negro rivers. In addition, our results suggest that reservoirs built in the Amazon region in the last decade are also affecting sediment transport. Our modeling outputs provide unprecedented information about the status of sediment dynamics in SA, and a means to develop evidence-based strategies and transboundary policies related to continental-wide sediment dynamics and the conservation and restoration of ecosystems.

Section: Study Areamentioning

confidence: 99%

Section: Study Areamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Human-induced changes in South American sediment fluxes from 1984 to 2019

Fagundes

Fan

et al. 2023

Preprint

“…Examples include the introduction of basin-scale inundation schemes that were later introduced to other river basins (Andriambeloson et al, 2020;, at continental scale (Siqueira et al, 2018) and at the global-scale (Alkama et al, 2010;Decharme et al, 2012;Yamazaki et al, 2011). Recent advances in large-scale sediment transport using RS observations and modeling followed a similar path, with pioneering works in Amazon (Section 4.4) being followed by progress for all of South America (Fagundes et al, 2021).…”

Section: The Benefits Of the Lessons Learned In The Amazon To Underst...mentioning

confidence: 99%

“…The move to hyper-resolution models has been promoted at a global scale due to the development of new numerical techniques, equation sets, and software engineering, as well as increased computing power (Bates et al, 2018). Such modeling systems could then be coupled to models of other processes, as recently done by researchers aiming at understanding flooding impacts on photosynthesis and biosphere in general (Aderson de Castro et al, 2018), feedbacks between surface waters and atmosphere (Santos et al, 2019), sediment exports and floodplain trapping (Fagundes et al, 2021;Rudorff et al, 2018), carbon storage and emissions through wetlands and uplands (Hastie et al, 2019;Lauerwald et al, 2020), and dynamics of biogeochemistry cycles at the basin scale or over wetlands (Guilhen et al, 2020). All these efforts will require additional RS data and will move forward our predictability of the effects of ongoing environmental changes in the Amazon basin.…”

Section: Table 6 Summary Of Main Differences Between Hydrologic and H...mentioning

confidence: 99%

Amazon Hydrology From Space: Scientific Advances and Future Challenges

Fassoni‐Andrade

Papa

et al. 2021

Reviews of Geophysics

Self Cite

As the largest river basin on Earth, the Amazon is of major importance to the world's climate and water resources. Over the past decades, advances in satellite‐based remote sensing (RS) have brought our understanding of its terrestrial water cycle and the associated hydrological processes to a new era. Here, we review major studies and the various techniques using satellite RS in the Amazon. We show how RS played a major role in supporting new research and key findings regarding the Amazon water cycle, and how the region became a laboratory for groundbreaking investigations of new satellite retrievals and analyses. At the basin‐scale, the understanding of several hydrological processes was only possible with the advent of RS observations, such as the characterization of "rainfall hotspots" in the Andes‐Amazon transition, evapotranspiration rates, and variations of surface waters and groundwater storage. These results strongly contribute to the recent advances of hydrological models and to our new understanding of the Amazon water budget and aquatic environments. In the context of upcoming hydrology‐oriented satellite missions, which will offer the opportunity for new synergies and new observations with finer space‐time resolution, this review aims to guide future research agenda toward integrated monitoring and understanding of the Amazon water from space. Integrated multidisciplinary studies, fostered by international collaborations, set up future directions to tackle the great challenges the Amazon is currently facing, from climate change to increased anthropogenic pressure.

Amazon hydrology from space: scientific advances and future challenges

Fassoni‐Andrade

Papa³

et al. 2021

Preprint

Self Cite

As the largest river basin on Earth, the Amazon is of major importance to the world's climate and water resources. Over the past decades, advances in satellite-based remote sensing (RS) have brought our understanding of its terrestrial water cycle and the associated hydrological processes to a new era. Here, we review major studies and the various techniques using satellite RS in the Amazon. We show how RS played a major role in supporting new research and key findings regarding the Amazon water cycle, and how the region became a laboratory for groundbreaking investigations of new satellite retrievals and analyses. At the basin-scale, the understanding of several hydrological processes was only possible with the advent of RS observations, such as the characterization of "rainfall hotspots" in the Andes-Amazon transition, evapotranspiration rates, and variations of surface waters and groundwater storage. These results strongly contribute to the recent advances of hydrological models and to our new understanding of the Amazon water budget and aquatic environments. In the context of upcoming hydrology-oriented satellite missions, which will offer the opportunity for new synergies and new observations with finer space-time resolution, this review aims to guide future research agenda toward integrated monitoring and understanding of the Amazon water from space. Integrated multidisciplinary studies, fostered by international collaborations, set up future directions to tackle the great challenges the Amazon is currently facing, from climate change to increased anthropogenic pressure. Plain Language SummaryThe Amazon basin is the largest river basin in the world, characterized by complex hydrological processes that connect high rates of precipitation, extensive floodplains, dense tropical forests, complex topography, and large variations in freshwater storage and discharge. It plays a key role in the water, energy, and carbon cycles and interacts with the global climate system. Earth observations have played a major role in supporting research in Amazon hydrology, and the characterization of several hydrological processes was only possible with the help of remote sensing data. The basin is now facing great risk under current climate change and increased anthropogenic pressure and the resulting environmental alterations require a better understanding of the overall basin's water cycle across scales. We review the strengths and limitations of observations from satellites in the context of the current and upcoming hydrology-oriented satellite missions, and we make recommendations for improving satellite observations of the Amazon basin water cycle, along with an interdisciplinary and stepwise approach to guide research for the next decades.