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The Brazilian Cerrado, one of the most threatened biomes of our planet, illustrates the challenges and opportunities of reconciling economic development with conservation of land and water ecosystems. Here, we assess the state of the art of and present new information on the impacts of agricultural expansion, dams, and water use, and make recommendations for basin management, conservation, and restoration of water‐related Cerrado ecosystems and rivers. The conservation of the Cerrado requires not only the preservation of remnants of its vegetation but also the ability to keep the hydro‐geomorphological and ecological functionality of its rivers, particularly the Araguaia River, the last large well preserved and unregulated system. If business as usual continues, the Cerrado riverine ecosystems may never rebound.

Sand mining is one of the major sustainability challenges of the 21st century. Rates of extraction are surpassing sand supply, and ensuing sand starvation is adversely impacting channel-floodplains and deltas. Therefore, quantifying sand mining’s location and extent, through global monitoring and detection, particularly in fluvial systems, is becoming a priority. Sand mining by dredges and barges (extraction of sand and secondarily gravel) in South East Asian rivers, including illegal sand mining, has become rampant, and a monitoring system is not yet in place. Here, we present a high-resolution remote sensing-based mining monitoring system for sand mining in fluvial systems. We used Sentinel-1 mission, a radar component of the Copernicus joint initiative of the European Commission (EC) and the European Space Agency (ESA). The system, tested in the Ayeyarwady, the second largest river in SE Asia, detects sand mining by barges almost in real-time with a satisfactory accuracy level. An additional advantage of the monitoring system is that it does not incur any costs, making it accessible to multiple users, decision-makers, and stakeholders.

Loess, loess-like, sandy loess, and sandy-silty fluvial–aeolian deposits are intercalated to fluvial sediments and lie on a flat surface under intense agricultural land use in Bardibas, Mahottari district, central Nepal. To identify the depositional processes and provenance, we carried out geochemical, mineralogical, SEM, and grain-size analyses. Optically stimulated luminescence (OSL) dating shows the aeolian deposits are from the late Holocene (1.0–4.8 ka). Our results demonstrate that the loess and loess-like deposits (i) were dominantly sourced locally from deflation Quaternary sediments of the Terai Plain; (ii) are related to the composition of Siwalik rocks; and (iii) were deposited during dry periods of weak activity of the Indian Summer Monsoon.

More than a hundred hydropower dams have already been built in the Amazon basin and numerous proposals for further dam constructions are under consideration. The accumulated negative environmental effects of existing dams and proposed dams, if constructed, will trigger massive hydrophysical and biotic disturbances that will affect the Amazon basin's floodplains, estuary and sediment plume. We introduce a Dam Environmental Vulnerability Index to quantify the current and potential impacts of dams in the basin. The scale of foreseeable environmental degradation indicates the need for collective action among nations and states to avoid cumulative, far-reaching impacts. We suggest institutional innovations to assess and avoid the likely impoverishment of Amazon rivers.

The Peruvian Amazon is known for harboring the greatest biodiversity on the planet, with a world record for biodiversity per unit area. Previous studies suggested that the high ecological value depends on correlations between ecosystem functionality and seasonal inundation control vegetation patches. However, the knowledge on how river morphodynamics and its complex erosion-depositional processes influence the aquatic mosaic and fishing activity in the region is still incipient. This study examines the hydrogeomorphology of the Peruvian tropical wetland of Pacaya Samiria, located in Western Amazonia, and its role in the distribution of aquatic habitats. By using remote sensing techniques, the hydrogeomorphological connectivity that bounds the Pacaya Samiria National Reserve is characterized by ancient to modern river processes. Additionally, river signatures developed by the Ucayali, Marañon, Huallaga, Pacaya, and Samiria Rivers overlap with fish extraction and dominant vegetation to describe how geomorphology is associated with the spatial distribution of fishing zones. Results indicated that paleochannels regulate wetland drainage within the Ucamara Depression, supporting stational water stagnation, vegetation cover, and formation of carbon rich detritus, relevant aspects to understand fish traits. Moreover, the Ucayali River dominates river dynamics in the Pacaya Samiria wetland, thus playing a pivotal role in shaping the complexity of streams and lakes. Furthermore, underfit-scavenger meandering rivers are observed in areas where paleochannels from large rivers are found. A geomorphological characterization of drainage patterns in freshwater environments, such as Amazonian wetlands, is crucial to develop sound management strategies. This methodological approach is expected to support decision-making in conservation actions in Amazonian environments based on understanding wetland connectivity and hydrogeomorphological behavior and their influence on commercial fisheries.

The Ayeyarwady (Irrawaddy) is the second largest river of Southeast Asia and one of the rivers with the highest load of suspended sediment delivered to the sea in the world. The Ayeyarwady is the lifeline of Myanmar which concentrates the majority of the population and GDP of the country. It is the main way of transport, a source of fluvial aggregates for development projects, hydropower, and the basin plays a major role in food supply and irrigation. Despite the Ayeyarwady ranking amongst the world's largest rivers and its vital importance to Myanmar, scarce research has been undertaken to understand its morphodynamics and sediment transport regime. Current load estimates still heavily rely on the only systematic study of sediment transport dating back to the 19th century. Here, we provide a novel estimate for the recent washload sediment transport based on a field calibrated remote sensing model of surface suspended sediments concentrations. We show that the Ayeyarwady has likely become the river with the second or third largest delivery of washload to the sea in the world since it has so far been much less affected by damming compared to the vast majority of other rivers.

White‐sand vegetation (WSV) harbors a unique avifauna within Amazonia, including species with patchy distributions. The history of these species' populations is likely related to variation in the availability and connectivity among WSV patches though time. By investigating the phylogeographic history of WSV bird species, we aim to better understand the dynamic evolution of forested and open habitats in Amazonia. Here, we perform a phylogeographic analysis of two WSV specialist bird species, a tanager, Tachyphonus phoenicius, and a hummingbird, Polytmus theresiae. We obtained and analyzed sequences of one mitochondrial and one nuclear gene region from 152 individuals. Results indicate that the two species have different histories. Tachyphonus phoenicius split from its Atlantic Forest/Cerrado sister clade at about 11 Ma and includes two divergent lineages, north and south of the Amazon River. Polytmus theresiae split from its Tepuian sister group at about 2.5 Ma and shows no genetic structure within Amazonia. Both lineages of T. phoenicius and P. theresiae show signs of recent population expansion. Although the two WSV species originated at different moments, and show distinct patterns of population structure, both seem to have expanded their population sizes recently, indicating that availability of white‐sand habitats may have been increasing historically and the connectivity among different white‐sand patches may have been higher in the recent past.