{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,4]],"date-time":"2026-03-04T16:36:37Z","timestamp":1772642197295,"version":"3.50.1"},"reference-count":71,"publisher":"MDPI AG","issue":"6","license":[{"start":{"date-parts":[[2024,3,16]],"date-time":"2024-03-16T00:00:00Z","timestamp":1710547200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>The Amazon, the world\u2019s largest rainforest, faces a severe historic drought. The Rio Negro River, one of the major Amazon River tributaries, reached its lowest level in a century in October 2023. Here, we used a U-net deep learning model to map water surfaces in the Rio Negro River basin every 12 days in 2022 and 2023 using 10 m spatial resolution Sentinel-1 satellite radar images. The accuracy of the water surface model was high, with an F1-score of 0.93. A 12-day mosaic time series of the water surface was generated from the Sentinel-1 prediction. The water surface mask demonstrated relatively consistent agreement with the global surface water (GSW) product from the Joint Research Centre (F1-score: 0.708) and with the Brazilian MapBiomas Water initiative (F1-score: 0.686). The main errors of the map were omission errors in flooded woodland, in flooded shrub, and because of clouds. Rio Negro water surfaces reached their lowest level around the 25th of November 2023 and were reduced to 68.1% (9559.9 km2) of the maximum water surfaces observed in the period 2022\u20132023 (14,036.3 km2). Synthetic aperture radar (SAR) data, in conjunction with deep learning techniques, can significantly improve near-real-time mapping of water surfaces in tropical regions.<\/jats:p>","DOI":"10.3390\/rs16061056","type":"journal-article","created":{"date-parts":[[2024,3,18]],"date-time":"2024-03-18T04:25:15Z","timestamp":1710735915000},"page":"1056","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":10,"title":["The Amazon\u2019s 2023 Drought: Sentinel-1 Reveals Extreme Rio Negro River Contraction"],"prefix":"10.3390","volume":"16","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-9623-1182","authenticated-orcid":false,"given":"Fabien H.","family":"Wagner","sequence":"first","affiliation":[{"name":"Institute of the Environment and Sustainability, University of California, Los Angeles, CA 90095, USA"},{"name":"NASA-Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91105, USA"},{"name":"CTREES.org, Pasadena, CA 91105, USA"}]},{"given":"Samuel","family":"Favrichon","sequence":"additional","affiliation":[{"name":"NASA-Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91105, USA"},{"name":"CTREES.org, Pasadena, CA 91105, USA"}]},{"given":"Ricardo","family":"Dalagnol","sequence":"additional","affiliation":[{"name":"Institute of the Environment and Sustainability, University of California, Los Angeles, CA 90095, USA"},{"name":"NASA-Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91105, USA"},{"name":"CTREES.org, Pasadena, CA 91105, USA"}]},{"given":"Mayumi C. M.","family":"Hirye","sequence":"additional","affiliation":[{"name":"Institute of the Environment and Sustainability, University of California, Los Angeles, CA 90095, USA"},{"name":"CTREES.org, Pasadena, CA 91105, USA"},{"name":"Quap\u00e1 Lab, Faculty of Architecture and Urbanism, University of S\u00e3o Paulo\u2014USP, S\u00e3o Paulo 05508-900, SP, Brazil"}]},{"given":"Adugna","family":"Mullissa","sequence":"additional","affiliation":[{"name":"Institute of the Environment and Sustainability, University of California, Los Angeles, CA 90095, USA"},{"name":"CTREES.org, Pasadena, CA 91105, USA"}]},{"given":"Sassan","family":"Saatchi","sequence":"additional","affiliation":[{"name":"Institute of the Environment and Sustainability, University of California, Los Angeles, CA 90095, USA"},{"name":"NASA-Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91105, USA"},{"name":"CTREES.org, Pasadena, CA 91105, USA"}]}],"member":"1968","published-online":{"date-parts":[[2024,3,16]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"412","DOI":"10.1007\/s13280-014-0610-z","article-title":"Amazonian freshwater habitats experiencing environmental and socioeconomic threats affecting subsistence fisheries","volume":"44","author":"Alho","year":"2015","journal-title":"Ambio"},{"key":"ref_2","unstructured":"Filizola, N., Sp\u00ednola, N., Arruda, W., Seyler, F., Calmant, S., and Silva, J. 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