{"schema":"https://ver.cy/schemas/card/1.0.0","id":"vr.tr.international-scale-of-river-difficulty","code":"thing-q1898028","url":"https://ver.cy/models/thing/q1898028/","name":"International Scale of River Difficulty","alternateNames":[],"kind":"thing","status":"published","version":"0.1.0-research.1","language":"en","classifiers":{"family":"Thing Registry","category":"Activities and processes","entryKind":"thing","plane":"ACT","domain":["ACT.ACT"],"industry":[],"navPath":"","tags":[],"facets":{}},"whatItIs":"The International Scale of River Difficulty is an ordinal classification of whitewater rapids and river sections into Classes I-VI according to navigational difficulty, obstacles, and the demands and consequences of passage under particular flow conditions.","purpose":"Enable an agent to interpret, compare and qualify river-difficulty ratings while identifying the evidence needed before using them in paddling decisions.","scope":{"in":["Definitions and notation associated with identified editions of the scale","Assignment of a class to a specified rapid, line or river section","Evidence and conditions supporting a difficulty rating","Regional interpretation, disputed classifications and rating revisions","Limits on using difficulty classes to support paddling decisions"],"out":["River geography and hydrological forecasting","Individual paddler competence and qualifications","Watercraft design and equipment certification","Detailed rescue procedures and expedition plans","Access rights, closures and navigation permissions"],"boundaries":[]},"distinguishingFeatures":["Classifies navigational difficulty through descriptive classes rather than directly measuring discharge, gradient or wave height.","A rating must identify both the scale convention and the river feature to which it applies; an unqualified number is insufficient.","Distinguishes a classification system from a guidebook's particular rating assertion.","Requires edition-aware interpretation: the inspected American Whitewater 2024 presentation lists Classes 1-5, so other class labels require their own supporting definition.","Does not treat a difficulty class as a personal competence certificate or authorization to run a rapid."],"structure":{"bundles":[{"id":"class-definitions-and-editions","name":"Class definitions and editions","description":"Establish the meaning and documentary basis of the classification being used.","layers":[{"id":"documented-scale-identity","name":"Documented scale identity","description":"Connect the registered concept to specific published formulations.","findings":[{"id":"edition-specific-class-vocabulary","name":"Edition-specific class vocabulary","description":"The inspected 2024 American Whitewater presentation describes Classes 1-5; record this as an edition-specific observation. Source: [American Whitewater scale, 2024](https://site-media.americanwhitewater.org/Scale-of-River-Difficulty-Safety-Code-2024.pdf).","questions":[{"text":"Which publication and edition define the classes used by this rating?","id":"edition-specific-class-vocabulary-q01","kind":"provenance"},{"text":"Does that edition define every class label appearing in the rating?","id":"edition-specific-class-vocabulary-q02","kind":"definition"}]}]},{"id":"notation-and-class-boundaries","name":"Notation and class boundaries","description":"Interpret written grades without silently importing another convention.","findings":[{"id":"qualified-grade-interpretation","name":"Qualified grade interpretation","description":"Preserve the reported expression and establish the documented meaning of Roman or Arabic numerals, modifiers, ranges and any subdivisions before normalizing them.","questions":[{"text":"What does each modifier, range or subdivision mean in the source's convention?","id":"qualified-grade-interpretation-q01","kind":"definition"},{"text":"Which descriptive criterion distinguishes the assigned class from its neighboring classes?","id":"qualified-grade-interpretation-q02","kind":"boundary"}]}]}]},{"id":"rating-subject-and-extent","name":"Rating subject and extent","description":"Specify exactly which navigable feature or section a rating describes.","layers":[{"id":"rapid-line-and-section","name":"Rapid, line and section","description":"Anchor the class assertion to a bounded subject.","findings":[{"id":"spatially-bounded-rating","name":"Spatially bounded rating","description":"Require enough spatial detail to distinguish the rated rapid or line from nearby alternatives and the containing run.","questions":[{"text":"Does the rating describe a named rapid, a particular line or a section with explicit endpoints?","id":"spatially-bounded-rating-q01","kind":"boundary"},{"text":"Which alternate channels, bypasses or portaged features are excluded from the rated subject?","id":"spatially-bounded-rating-q02","kind":"boundary"}]}]},{"id":"section-grade-composition","name":"Section grade composition","description":"Clarify how individual difficulties contribute to a section's headline grade.","findings":[{"id":"headline-grade-and-exceptions","name":"Headline grade and exceptions","description":"Record the source's rule for a section grade, including whether it denotes typical difficulty, maximum difficulty or a qualified combination.","questions":[{"text":"How was the section's headline class derived from its individual rapids?","id":"headline-grade-and-exceptions-q01","kind":"provenance"},{"text":"Which harder exceptions and sustained sequences must accompany the headline grade?","id":"headline-grade-and-exceptions-q02","kind":"definition"}]}]}]},{"id":"difficulty-evidence-and-judgment","name":"Difficulty evidence and judgment","description":"Make a classification's observational basis and interpretive uncertainty explicit.","layers":[{"id":"navigation-demands","name":"Navigation demands","description":"Relate reported river features to the applicable class descriptors.","findings":[{"id":"descriptor-supported-assignment","name":"Descriptor-supported assignment","description":"Collect observations about required maneuvers, available lines, hydraulic features and continuity, then explain their relationship to the cited class definition.","questions":[{"text":"Which observed features and required maneuvers support the proposed class?","id":"descriptor-supported-assignment-q01","kind":"measurement"},{"text":"Which observations are missing or inconsistent with that class's descriptors?","id":"descriptor-supported-assignment-q02","kind":"boundary"}]}]},{"id":"local-calibration-and-disagreement","name":"Local calibration and disagreement","description":"Represent differences between assessors and regional usage.","findings":[{"id":"traceable-rating-disagreement","name":"Traceable rating disagreement","description":"Retain competing assessments with their conditions and reasoning; distinguish disagreement about observations from disagreement about class boundaries.","questions":[{"text":"Which raters or guidebooks disagree, and what observations or local comparisons support each assessment?","id":"traceable-rating-disagreement-q01","kind":"provenance"},{"text":"Does the disagreement persist after matching flow, rated line and scale edition?","id":"traceable-rating-disagreement-q02","kind":"boundary"}]}]}]},{"id":"conditions-and-rating-validity","name":"Conditions and rating validity","description":"Determine when a recorded rating can reasonably describe the river being considered.","layers":[{"id":"flow-conditioned-rating","name":"Flow-conditioned rating","description":"Associate a grade with documented water conditions.","findings":[{"id":"reference-water-conditions","name":"Reference water conditions","description":"Record the source's flow or stage interval and gauge relationship without assuming that difficulty changes monotonically with discharge.","questions":[{"text":"At what flow or stage, measured where and when, was this difficulty assessed?","id":"reference-water-conditions-q01","kind":"measurement"},{"text":"What evidence supports applying the rating outside that observed interval?","id":"reference-water-conditions-q02","kind":"boundary"}]}]},{"id":"channel-change-and-reassessment","name":"Channel change and reassessment","description":"Track events that may invalidate an earlier class assertion.","findings":[{"id":"rating-revalidation-trigger","name":"Rating revalidation trigger","description":"Separate historical ratings from current applicability assessments and attach reported changes to a request for fresh evidence.","questions":[{"text":"What channel alterations or new obstructions have been reported since the supporting observation?","id":"rating-revalidation-trigger-q01","kind":"provenance"},{"text":"What updated observation is needed before presenting the rating as applicable?","id":"rating-revalidation-trigger-q02","kind":"action"}]}]}]},{"id":"planning-use-and-inference-limits","name":"Planning use and inference limits","description":"Define what an agent may infer from a difficulty class and what requires separate evidence.","layers":[{"id":"difficulty-and-consequence","name":"Difficulty and consequence","description":"Prevent a headline grade from absorbing every dimension of exposure.","findings":[{"id":"separate-consequence-context","name":"Separate consequence context","description":"Keep navigation difficulty distinguishable from supporting information about remoteness, cold water, escape opportunities and rescue access.","questions":[{"text":"Which consequential features are conveyed by the cited class definition, and which require separate description?","id":"separate-consequence-context-q01","kind":"boundary"},{"text":"What contextual information must accompany this rating for the intended planning use?","id":"separate-consequence-context-q02","kind":"action"}]}]},{"id":"party-and-craft-interface","name":"Party and craft interface","description":"Connect class interpretation to independently assessed participants and equipment.","findings":[{"id":"bounded-suitability-inference","name":"Bounded suitability inference","description":"Use the class to identify comparison questions for party and craft models; record any craft assumptions behind the rating instead of declaring universal suitability.","questions":[{"text":"What craft type and paddling assumptions underlie the source's assessment?","id":"bounded-suitability-inference-q01","kind":"provenance"},{"text":"Which independently established party capabilities and current river observations are required before a suitability judgment?","id":"bounded-suitability-inference-q02","kind":"action"}]}]}]},{"id":"evidence-and-external-alignment","name":"Evidence and external alignment","description":"What the world already says about this thing, gathered so the model can be checked against it.","layers":[{"id":"reported-evidence","name":"Reported evidence","description":"Findings from the breadth pass, kept separate from the structural claims.","findings":[{"id":"evidence-confidence-notes","name":"Check these first","description":"Recalled without web access and unsourced; every item is a lead to verify.","questions":[{"text":"Which of these check these first hold for the sense of International Scale of River Difficulty this model covers, and on what evidence?","id":"evidence-confidence-notes-q01","kind":"provenance"}]},{"id":"evidence-kinds","name":"Kinds and varieties","description":"Recalled without web access and unsourced; every item is a lead to verify.","questions":[{"text":"Which of these kinds and varieties hold for the sense of International Scale of River Difficulty this model covers, and on what evidence?","id":"evidence-kinds-q01","kind":"provenance"}]},{"id":"evidence-identifiers","name":"Identifiers and schemes","description":"Recalled without web access and unsourced; every item is a lead to verify.","questions":[{"text":"Which of these identifiers and schemes hold for the sense of International Scale of River Difficulty this model covers, and on what evidence?","id":"evidence-identifiers-q01","kind":"provenance"}]},{"id":"evidence-standards-and-regulation","name":"Standards and regulation","description":"Recalled without web access and unsourced; every item is a lead to verify.","questions":[{"text":"Which of these standards and regulation hold for the sense of International Scale of River Difficulty this model covers, and on what evidence?","id":"evidence-standards-and-regulation-q01","kind":"provenance"}]},{"id":"evidence-real-world-use","name":"Real-world use","description":"Recalled without web access and unsourced; every item is a lead to verify.","questions":[{"text":"Which of these real-world use hold for the sense of International Scale of River Difficulty this model covers, and on what evidence?","id":"evidence-real-world-use-q01","kind":"provenance"}]},{"id":"evidence-measurements","name":"Typical measurements","description":"Recalled without web access and unsourced; every item is a lead to verify.","questions":[{"text":"Which of these typical measurements hold for the sense of International Scale of River Difficulty this model covers, and on what evidence?","id":"evidence-measurements-q01","kind":"provenance"}]},{"id":"evidence-failure-modes-and-hazards","name":"Failure modes and hazards","description":"Recalled without web access and unsourced; every item is a lead to verify.","questions":[{"text":"Which of these failure modes and hazards hold for the sense of International Scale of River Difficulty this model covers, and on what evidence?","id":"evidence-failure-modes-and-hazards-q01","kind":"provenance"}]},{"id":"evidence-regional-variation","name":"Regional variation","description":"Recalled without web access and unsourced; every item is a lead to verify.","questions":[{"text":"Which of these regional variation hold for the sense of International Scale of River Difficulty this model covers, and on what evidence?","id":"evidence-regional-variation-q01","kind":"provenance"}]},{"id":"evidence-neighbours","name":"Neighbouring kinds and how to tell them apart","description":"Recalled without web access and unsourced; every item is a lead to verify.","questions":[{"text":"Which of these neighbouring kinds and how to tell them apart hold for the sense of International Scale of River Difficulty this model covers, and on what evidence?","id":"evidence-neighbours-q01","kind":"provenance"}]}]}]}]},"agentConduct":{"may":["Report the class of a river section from guidebooks or authorities, with the date and water level noted.","Explain what each class means for skills and equipment."],"mustNot":["State a river's class as fixed when it changes with water levels and conditions.","Encourage people to paddle sections above their documented ability.","Present a class rating as a guarantee of safety."],"requiresHuman":["Decisions to run, portage or rescue on a specific river section."]},"ethics":{"considerations":["Underrating a rapid can lead to drowning.","Rescuers are put at risk when people paddle beyond their skill."],"affectedParties":["Paddlers","Guides and rescuers","Clients of commercial trips"]},"owners":{"steward":"Nobody owns the scale; paddling organisations maintain and publish it.","roles":[],"masterSystems":[]},"relations":[{"target":"Q11659512","type":"parent","note":"registry parent class"}],"interaction":{"identity":{"applicability":"required","items":["Vercy registry: vr.tr.international-scale-of-river-difficulty","Wikidata: Q1898028 (https://www.wikidata.org/wiki/Q1898028)"]},"properties":{"applicability":"not-applicable","items":["Scale authority and edition: Named publisher or adopting body, document title, date and source location","Reported difficulty class: Original class expression plus its interpretation under the cited edition","Rated spatial subject: Identified rapid, selected line or bounded river section","Reference flow: Discharge in m³/s or ft³/s, or gauge stage in m or ft, with station and observation time","Difficulty evidence: Observed maneuvering demands, hydraulic features, obstacles and rapid continuity","Rating applicability: Supported for stated conditions, uncertain, disputed or superseded","Rating provenance: Rater or publication, observation date, publication date and supporting account"]},"recognition":{"applicability":"optional","items":["Appears as roman numerals I to VI on river guides, maps and signs.","Ratings may be qualified with plus or minus or with water level notes."]},"capabilities":{"applicability":"required","items":["Interpret a published class expression against its documented scale edition.","Compare ratings after checking spatial scope, reference conditions and regional convention.","Identify missing evidence that prevents a rating from supporting a proposed use.","Flag a rating for reassessment following reported channel or condition changes.","Explain which additional river, party and equipment information a planning decision requires."]},"hazards":{"applicability":"required","items":["Ratings shift with floods, debris and seasons.","Different countries apply the scale differently."]},"interfaces":{"applicability":"required","items":["American Whitewater publishes the International Scale of River Difficulty with Classes I-VI as a river difficulty classification rather than a legally enforceable safety certification."]},"context":{"applicability":"required","items":["The scale is used in paddling guidebooks, river descriptions and trip planning to communicate the difficulty of rapids or river sections.","Ratings help paddlers compare expected demands with their skills while accounting for water level, changing obstacles and the limitations of published descriptions."]}},"sources":[{"title":"Wikidata item Q1898028: International Scale of River Difficulty","url":"https://www.wikidata.org/wiki/Q1898028","note":"identity and sense of the item"},{"title":"Wikipedia: International scale of river difficulty","url":"https://en.wikipedia.org/wiki/International_scale_of_river_difficulty","note":"general description of the item"}],"openQuestions":["How do authoritative historical and regional formulations relate to the inspected 2024 American Whitewater presentation, particularly concerning Class VI and Class V subdivisions?","Which sources formally define plus/minus modifiers, grade ranges and parenthetical exceptional-rapid notation?","What documented conventions govern assigning one headline class to a section containing varied rapid difficulties?","How explicitly do different adopting organizations account for craft type when assigning or interpreting grades?","Which benchmark rapids have sufficiently documented flow conditions and reassessment histories to support defensible regional comparisons?"],"resources":{"spec":"/models/things/publications/thing-q1898028/spec.json"},"provenance":{"origin":"thing registry research (pass 2)","builtFrom":["models/things/publications/thing-q1898028/spec.json"],"providers":["Codex"],"researchStatus":"unreviewed","generatedAt":"2026-09-12T10:32:05Z","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":"not-applicable","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","interaction.properties":"Plane ACT: no invented physical properties."},"score":1.0}}