{"schema":"https://ver.cy/schemas/card/1.0.0","id":"vr.tr.log-jam","code":"thing-q1797874","url":"https://ver.cy/models/thing/q1797874/","name":"log jam","alternateNames":[],"kind":"thing","status":"published","version":"0.2.0-wave.2","language":"en","classifiers":{"family":"Thing Registry","category":"Physical world and living systems","entryKind":"thing","plane":"PHY","domain":["PHY.FLW"],"industry":[],"navPath":"","tags":[],"facets":{}},"whatItIs":"An accumulation of logs or woody debris that blocks or partly blocks a river or stream, formed naturally by fallen trees or historically by timber floated downstream during log drives, creating barriers that alter flow, trap sediment, form pools and habitat, and sometimes cause flooding or dangerous releases; log jams were a hazard and a feature of timber transport and are now valued in river restoration for their ecological role.","purpose":"Let an agent explain log jams and how they form and behave, describe their ecological and hydrological roles, describe their history in timber transport, and support river management and safety questions.","scope":{"in":[],"out":[],"boundaries":[]},"distinguishingFeatures":["Woody accumulation","Flow obstruction","Habitat creation","Historical hazard"],"structure":{"bundles":[{"id":"understand","name":"Understand","description":"What a log jam is.","layers":[{"id":"formation","name":"Formation","description":"Formation and behaviour.","findings":[{"id":"formation-finding","name":"Formation","description":"Formation.","questions":[{"text":"How do log jams form, and how do they alter flow, sediment and channel shape?","kind":"definition"},{"text":"Is a natural, historical or engineered jam meant?","kind":"boundary"}]}]},{"id":"ecology","name":"Ecology","description":"Ecology.","findings":[{"id":"ecology-finding","name":"Ecology","description":"Ecology.","questions":[{"text":"What habitat and ecological functions do log jams provide for fish and other life?","kind":"provenance"},{"text":"Which entry fits river ecology?","kind":"action"}]}]}]},{"id":"manage","name":"Manage","description":"Management and restoration.","layers":[{"id":"restoration","name":"Restoration","description":"Engineered log jams.","findings":[{"id":"restoration-finding","name":"Restoration","description":"Restoration.","questions":[{"text":"How are engineered log jams designed and used in river restoration?","kind":"provenance"},{"text":"Which entry fits river restoration?","kind":"action"}]}]},{"id":"risk","name":"Risk","description":"Flood risk and removal.","findings":[{"id":"risk-finding","name":"Risk","description":"Risk.","questions":[{"text":"When do log jams pose flood or safety risks, and how do authorities decide on removal?","kind":"provenance"},{"text":"Is a dangerous jam present now that needs authorities?","kind":"boundary"}]}]}]},{"id":"history","name":"History","description":"Timber history.","layers":[{"id":"drives","name":"Drives","description":"Log drives.","findings":[{"id":"drives-finding","name":"Drives","description":"Drives.","questions":[{"text":"How did log jams arise during timber drives, and how were they broken, according to historians?","kind":"provenance"},{"text":"Which entry fits timber floating?","kind":"action"}]}]},{"id":"culture","name":"Culture","description":"Culture and language.","findings":[{"id":"culture-finding","name":"Culture","description":"Culture.","questions":[{"text":"How do log jams appear in folklore, and how did the term become a metaphor?","kind":"provenance"},{"text":"Which references are standard?","kind":"provenance"}]}]}]},{"id":"learn","name":"Learn","description":"Teaching.","layers":[{"id":"teach","name":"Teach","description":"Teaching.","findings":[{"id":"teach-finding","name":"Teach","description":"Teaching.","questions":[{"text":"How can log jams be used to teach river processes?","kind":"action"},{"text":"Which misconceptions arise?","kind":"provenance"}]}]},{"id":"research","name":"Research","description":"Research.","findings":[{"id":"research-finding","name":"Research","description":"Research.","questions":[{"text":"What research exists on large wood dynamics in rivers, with findings attributed?","kind":"provenance"},{"text":"Which findings are contested?","kind":"boundary"}]}]}]}]},"agentConduct":{"may":["Explain how log jams form and their ecological and hydrological roles.","Describe their history in timber transport.","Relay river safety warnings from authorities."],"mustNot":["Advise people to walk on or clear a log jam themselves.","Advise boaters to approach jams.","Advise removing wood from rivers without permission.","Understate flood risk from a sudden release."],"requiresHuman":["Removing or breaking up a log jam."]},"ethics":{"considerations":["Log jams can kill boaters and swimmers caught in them.","Wood in rivers provides habitat; removal harms fish."],"affectedParties":["Boaters and swimmers","People downstream","River wildlife"]},"owners":{"steward":"The riparian landowner; river and environmental authorities regulate works.","roles":[],"masterSystems":[]},"relations":[{"target":"Q116844065","type":"parent","note":"registry parent class"},{"target":"Q6980653","type":"parent","note":"registry parent class"},{"target":"natural barrier","type":"related","note":"category"},{"target":"accumulation","type":"related","note":"category"},{"target":"woody plant","type":"related","note":"the trees forming jams"},{"target":"fish ladder","type":"related","note":"river structures affecting fish passage"}],"interaction":{"identity":{"applicability":"required","items":["Vercy registry: vr.tr.log-jam","Wikidata: Q1797874 (https://www.wikidata.org/wiki/Q1797874)"]},"properties":{"applicability":"required","items":["Channel blockage fraction:  % - Estimate the proportion of the channel cross section obstructed by wood at a stated water level.","Jam length:  m - Measure the upstream to downstream extent using a field survey or scaled imagery.","Wood volume:  m3 - Estimate the solid wood volume from surveyed log dimensions while distinguishing it from the jam's volume including voids.","Water level difference:  m - Measure the difference between upstream and downstream water surface elevations under a stated flow condition."]},"recognition":{"applicability":"required","items":["Logs or woody debris blocking a watercourse","Natural jams and historical timber drive jams","A beaver dam is built by animals; a debris flow is a moving mass; an ice jam is frozen","Tangled masses of logs across a river."]},"capabilities":{"applicability":"required","items":["explain formation and behaviour","describe ecological roles","describe history","support management questions"]},"hazards":{"applicability":"required","items":["Sudden release and flooding","Danger to boaters and workers","Removing ecologically valuable wood"]},"interfaces":{"applicability":"required","items":["River management and flood risk rules","Restoration guidelines for large wood","Historical timber floating regulations"]},"context":{"applicability":"required","items":["Accumulations of logs blocking rivers.","natural large wood jams","historical log drive jams","engineered log jams in restoration","jams at bridges and culverts","flood debris jams"]}},"sources":[{"title":"Wikidata item Q1797874: log jam","url":"https://www.wikidata.org/wiki/Q1797874","note":"identity and sense of the item"},{"title":"Wikipedia: Log jam","url":"https://en.wikipedia.org/wiki/Log_jam","note":"general description of the item"}],"openQuestions":["Should large wood in rivers be a separate entry?","How should restoration guidance be linked?","How should timber history be linked?"],"resources":{"spec":"/models/things/publications/thing-q1797874/spec.json"},"provenance":{"origin":"thing registry research (pass 2)","builtFrom":["models/things/publications/thing-q1797874/spec.json"],"providers":["Claude"],"researchStatus":"unreviewed","generatedAt":"2026-09-12T06:07:39Z","builder":"tools/build_cards.py@1.0.0"},"completeness":{"sections":{"classifiers":"filled","whatItIs":"filled","purpose":"filled","distinguishingFeatures":"filled","structure":"filled","agentConduct":"filled","ethics":"filled","owners":"filled","relations":"filled","interaction.identity":"filled","interaction.properties":"filled","interaction.recognition":"filled","interaction.capabilities":"filled","interaction.hazards":"filled","interaction.interfaces":"filled","interaction.context":"filled","sources":"filled"},"notes":{"_gate":"Published through the thing publication gate 1.0 on 2026-10-07T10:10:27+00:00: completeness 1.00; sense: Wikidata description; 2 live sources; review by codex: pass"},"score":1.0}}