{"uid":"cap_YqgfgSxNd0vA_IJ3rCEi2","slug":"manning-flow-velocity-hydraulic-radius-calculator-fbbaab04","name":"Manning Flow, Velocity & Hydraulic Radius Calculator","description":"Manning flow, velocity and hydraulic radius for rectangular, trapezoidal, triangular or part-full circular channels, SI or US.","url":"https://hydrology-calc.x402tookit.com/manning-flow?utm_source=zero.xyz","method":"GET","headers":{},"bodySchema":{"type":"object","$schema":"https://json-schema.org/draft/2020-12/schema","required":["input"],"properties":{"input":{"type":"object","required":["type","method"],"properties":{"type":{"type":"string","const":"http"},"method":{"enum":["GET"],"type":"string"},"queryParams":{"type":"object","required":["shape","depth","n","slope"],"properties":{"n":{"type":"number","description":"Manning roughness n (for example 0.013 concrete pipe, 0.035 natural channel)"},"depth":{"type":"number","description":"Flow depth in metres (units si) or feet (units us); for circular, not above the diameter"},"shape":{"type":"string","description":"rectangular, trapezoidal, triangular or circular"},"slope":{"type":"number","description":"Channel bed slope, dimensionless (m/m or ft/ft), for example 0.001"},"units":{"type":"string","description":"si (metres, constant 1.0; default) or us (feet, constant 1.486)"},"diameter":{"type":"number","description":"Pipe diameter in metres or feet (circular)"},"sideSlope":{"type":"number","description":"Side slope z, horizontal run per 1 vertical (trapezoidal, triangular)"},"bottomWidth":{"type":"number","description":"Bottom width in metres or feet (rectangular, trapezoidal)"}}}},"additionalProperties":false},"output":{"type":"object","required":["type"],"properties":{"type":{"type":"string"},"example":{"type":"object","properties":{"n":{"type":["null","number"]},"asOf":{"type":["null","string"]},"flow":{"type":["null","number"]},"depth":{"type":["null","number"]},"shape":{"type":["null","string"]},"slope":{"type":["null","number"]},"units":{"type":["null","string"]},"source":{"type":["null","string"]},"reasons":{"type":["array","null"],"items":{"type":"string"}},"summary":{"type":["null","string"]},"verdict":{"type":["null","string"]},"degraded":{"type":["boolean","null"]},"flowArea":{"type":["null","number"]},"flowUnit":{"type":["null","string"]},"topWidth":{"type":["null","number"]},"velocity":{"type":["null","number"]},"disclaimer":{"type":["null","string"]},"flowRegime":{"type":["null","string"]},"notChecked":{"type":["array","null"],"items":{"type":"string"}},"bottomWidth":{"type":["null","number"]},"froudeNumber":{"type":["null","number"]},"fullPipeFlow":{},"velocityUnit":{"type":["null","string"]},"hydraulicDepth":{"type":["null","number"]},"hydraulicRadius":{"type":["null","number"]},"wettedPerimeter":{"type":["null","number"]},"depthOverDiameter":{},"fractionOfFullFlow":{}}}}}}},"responseSchema":null,"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.02","displayCostAsset":"USDC","priceDynamic":false,"priceHint":null,"priceStatus":"priced","priceSource":"probe","requiresHandshake":false,"reviewCount":0,"rating":{"score":"0.00","successRate":"0.00","reviews":0,"stars":null,"state":"unrated"},"availabilityStatus":"unknown","priceObserved":null,"sessionDeposit":null,"pricing":{"kind":"static","summary":"$0.02/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.02","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.02","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm__WfkjVuUhWTlbmKP8QmZW","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.02","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Computes Manning open-channel flow rate, velocity, flow area, and hydraulic radius for rectangular, trapezoidal, triangular, or part-full circular channel cross-sections in SI or US customary units.","exampleAgentPrompt":"Calculate the Manning flow, velocity, and hydraulic radius for a rectangular concrete channel (n = 0.013) that is 2 metres wide, with a flow depth of 0.8 metres and a bed slope of 0.002, using SI units.","exampleUseCases":[{"title":"Irrigation canal design check","prompt":"I'm designing a trapezoidal irrigation canal with a bottom width of 1.5 metres, side slopes of 1.5 horizontal to 1 vertical, flow depth of 1.2 metres, Manning n of 0.025, and a bed slope of 0.0005. Can you calculate the discharge, velocity, and hydraulic radius in SI units?"},{"title":"Concrete storm-sewer culvert sizing","prompt":"For a circular concrete pipe culvert with a diameter of 1.2 metres flowing at a depth of 0.9 metres, Manning n of 0.013, and slope of 0.003, what is the Manning flow rate and velocity in SI units?"},{"title":"Natural earthen drainage ditch assessment","prompt":"I have a triangular earthen drainage ditch with side slopes of 2:1, a flow depth of 0.6 feet, Manning roughness of 0.035, and a channel slope of 0.004. Give me the discharge and velocity in US customary units."}],"resultDescription":"Returns computed flow rate Q (in m³/s or ft³/s), mean velocity, hydraulic radius, flow area, top width, wetted perimeter, and a plain-language summary of the hydraulic conditions. Also includes the input echo (shape, depth, slope, n, units), a verdict or warning if inputs are outside typical limits, and a degraded flag if results may be approximate.","failureModes":["Missing required parameters (shape, depth, n, slope) returns a validation error","Depth exceeding pipe diameter for circular shape causes rejection","Invalid shape string returns an error","Extreme slope or roughness values outside physically reasonable bounds may return a degraded or warning verdict","Unsupported unit string (not 'si' or 'us') may cause failure","Part-full circular depth very close to full-pipe diameter may produce numerical instability"],"whenToPreferThis":"Choose this endpoint when you need uniform (normal) flow calculations using Manning's equation for a known cross-section geometry and flow depth. It is ideal for engineering checks on channel capacity, velocity, and hydraulic radius across rectangular, trapezoidal, triangular, or circular shapes in both SI and US units. Prefer companion endpoints on the same host for solving normal depth from a known discharge, computing critical depth, or evaluating Froude number.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-11-02T18:32:49.060Z","isFirstParty":false,"canonicalSlug":"manning-flow-velocity-hydraulic-radius-calculator-fbbaab04"}