{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,19]],"date-time":"2026-01-19T15:42:44Z","timestamp":1768837364611,"version":"3.49.0"},"reference-count":24,"publisher":"MDPI AG","issue":"10","license":[{"start":{"date-parts":[[2021,5,18]],"date-time":"2021-05-18T00:00:00Z","timestamp":1621296000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001691","name":"Japan Society for the Promotion of Science","doi-asserted-by":"publisher","award":["16H06291"],"award-info":[{"award-number":["16H06291"]}],"id":[{"id":"10.13039\/501100001691","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>Constellations of small satellites equipped with synthetic aperture radar (SAR) payloads can realize observations in short time intervals independently from daylight and weather conditions and this technology is now in the early stages of development. This tool would greatly contribute to rapid flood monitoring, which is usually one of the main missions in upcoming plans, but few studies have focused on this potential application and a required observation performance for flood disaster monitoring has been unclear. In this study, we propose an unprecedented method for investigating how flood extents would be temporally and spatially observed with a SAR small-satellite constellation and for evaluating that observation performance via an original index. The virtual experiments of flood monitoring with designed constellations were conducted using two case studies of flood events in Japan. Experimental results showed that a SAR small-satellite constellation with sun-synchronous orbit at 570 km altitude, 30-km swath, 15\u201330\u00b0 incidence angle, and 20 satellites can achieve 87% acquisition of cumulative flood extent in total observations. There is a difference between the results of observation performance in two cases because of each flood\u2019s characteristics and a SAR satellite\u2019s observation system, which implies the necessity of individual assessments for various types of rivers.<\/jats:p>","DOI":"10.3390\/rs13101959","type":"journal-article","created":{"date-parts":[[2021,5,18]],"date-time":"2021-05-18T06:01:33Z","timestamp":1621317693000},"page":"1959","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":12,"title":["Potential of a SAR Small-Satellite Constellation for Rapid Monitoring of Flood Extent"],"prefix":"10.3390","volume":"13","author":[{"given":"Natsumi","family":"Kitajima","sequence":"first","affiliation":[{"name":"Department of Civil and Environmental Engineering, School of Environment and Society, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan"}]},{"given":"Rie","family":"Seto","sequence":"additional","affiliation":[{"name":"Department of Civil and Environmental Engineering, School of Environment and Society, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan"}]},{"given":"Dai","family":"Yamazaki","sequence":"additional","affiliation":[{"name":"Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan"}]},{"given":"Xudong","family":"Zhou","sequence":"additional","affiliation":[{"name":"Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1470-8483","authenticated-orcid":false,"given":"Wenchao","family":"Ma","sequence":"additional","affiliation":[{"name":"Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan"}]},{"given":"Shinjiro","family":"Kanae","sequence":"additional","affiliation":[{"name":"Department of Civil and Environmental Engineering, School of Environment and Society, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan"}]}],"member":"1968","published-online":{"date-parts":[[2021,5,18]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"161","DOI":"10.1007\/s12193-013-0139-7","article-title":"Real-Time Emergency Response: Improved Management of Real-Time Information during Crisis Situations","volume":"8","author":"Blum","year":"2013","journal-title":"J. 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