Spatio-temporal characterization of flash floods in small data-scarce watersheds of the tropical Kigezi highlands, southwestern Uganda

Spatio-temporal characterization of flash floods in small data-scarce watersheds of the tropical Kigezi highlands, southwestern Uganda | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Spatio-temporal characterization of flash floods in small data-scarce watersheds of the tropical Kigezi highlands, southwestern Uganda Violet Kanyiginya, Axel A. J. Deijns, David Mubiru, Grace Kagoro-Rugunda, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7695611/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 5 You are reading this latest preprint version Abstract Flash floods are widespread natural hazards, yet detailed field-based studies remain limited, especially in tropical regions where data on their occurrence and climate knowledge are scarce. Here, we characterize flash floods across eight small watersheds in the tropical Kigezi highlands of southwestern Uganda. We trained a network of river watchers, i.e. citizens from local communities, to monitor the main river in each watershed at fixed locations over two years. Their more than 1,000 observations were paired with rainfall data from gauges located within a 2–3 kilometre radius. We identify with certainty 20 flash floods and 10 bankfull (near-flood) events. Not all watersheds experienced such events despite similar climate conditions, underscoring the dominant role of local convective rainfall over general seasonal trends. In some cases, flash floods occurred despite low recorded rainfall nearby. Conversely, 17 ‘non-flash flood’ events were also observed, i.e., intense rainfall events with no associated flood. These mismatches between the recorded rainfall and associated flash flood patterns further highlight the importance of highly localised rainfall typical of tropical climates as a flood trigger. Land use and cover also influenced flash flood patterns. Flash floods were most frequent during land preparation and planting seasons, while non-flash flood events were observed in watersheds with stronger conservation and restoration practices. In contrast, the geomorphological and lithological characteristics of the watersheds did not explain flash flood occurrence. This analysis based on real-world data from tropical Africa offers practical insights into flash flood occurrence in an understudied type of environment. Natural hazards rainfall distribution land use and land cover citizen science river monitoring data acquisition Full Text Supplementary Files VioletKRainfalldataallwatersheds.csv Cite Share Download PDF Status: Under Review Version 1 posted Reviewers agreed at journal 09 Oct, 2025 Reviewers invited by journal 09 Oct, 2025 Editor invited by journal 04 Oct, 2025 Editor assigned by journal 23 Sep, 2025 First submitted to journal 23 Sep, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7695611","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":527067260,"identity":"9f8a1e48-8706-4b31-8336-6e9c4180a01e","order_by":0,"name":"Violet Kanyiginya","email":"data:image/png;base64,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","orcid":"https://orcid.org/0000-0003-4303-5302","institution":"Royal Museum for Central Africa: Koninklijk Museum voor Midden-Afrika","correspondingAuthor":true,"prefix":"","firstName":"Violet","middleName":"","lastName":"Kanyiginya","suffix":""},{"id":527067261,"identity":"cc04e4d3-92c9-4ef2-8784-5649bee00dda","order_by":1,"name":"Axel A. 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Uganda","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"natural-hazards","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"nhaz","sideBox":"Learn more about [Natural Hazards](https://www.springer.com/journal/11069)","snPcode":"11069","submissionUrl":"https://submission.nature.com/new-submission/11069/3","title":"Natural Hazards","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Natural hazards, rainfall distribution, land use and land cover, citizen science, river monitoring, data acquisition","lastPublishedDoi":"10.21203/rs.3.rs-7695611/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7695611/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eFlash floods are widespread natural hazards, yet detailed field-based studies remain limited, especially in tropical regions where data on their occurrence and climate knowledge are scarce. Here, we characterize flash floods across eight small watersheds in the tropical Kigezi highlands of southwestern Uganda. We trained a network of river watchers, i.e. citizens from local communities, to monitor the main river in each watershed at fixed locations over two years. Their more than 1,000 observations were paired with rainfall data from gauges located within a 2\u0026ndash;3 kilometre radius. We identify with certainty 20 flash floods and 10 bankfull (near-flood) events. Not all watersheds experienced such events despite similar climate conditions, underscoring the dominant role of local convective rainfall over general seasonal trends. In some cases, flash floods occurred despite low recorded rainfall nearby. Conversely, 17 \u0026lsquo;non-flash flood\u0026rsquo; events were also observed, i.e., intense rainfall events with no associated flood. These mismatches between the recorded rainfall and associated flash flood patterns further highlight the importance of highly localised rainfall typical of tropical climates as a flood trigger. Land use and cover also influenced flash flood patterns. Flash floods were most frequent during land preparation and planting seasons, while non-flash flood events were observed in watersheds with stronger conservation and restoration practices. In contrast, the geomorphological and lithological characteristics of the watersheds did not explain flash flood occurrence. This analysis based on real-world data from tropical Africa offers practical insights into flash flood occurrence in an understudied type of environment.\u003c/p\u003e","manuscriptTitle":"Spatio-temporal characterization of flash floods in small data-scarce watersheds of the tropical Kigezi highlands, southwestern Uganda","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-10-23 19:31:52","doi":"10.21203/rs.3.rs-7695611/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewerAgreed","content":"","date":"2025-10-09T11:50:17+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-10-09T11:20:08+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"Natural Hazards","date":"2025-10-04T21:53:54+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-09-24T03:49:02+00:00","index":"","fulltext":""},{"type":"submitted","content":"Natural Hazards","date":"2025-09-23T10:38:52+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"natural-hazards","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"nhaz","sideBox":"Learn more about [Natural Hazards](https://www.springer.com/journal/11069)","snPcode":"11069","submissionUrl":"https://submission.nature.com/new-submission/11069/3","title":"Natural Hazards","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"4df0ceec-b366-4108-9ea6-0fc22ffbeaca","owner":[],"postedDate":"October 23rd, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2025-10-23T19:31:53+00:00","versionOfRecord":[],"versionCreatedAt":"2025-10-23 19:31:52","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7695611","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7695611","identity":"rs-7695611","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}