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GET /v1/rational

Rational method

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10 free calls per day — no sign-up, no API key. Goes through the oanor gateway.

Custom headers (optional)
api.oanor.com/runoff-api

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Code snippets

curl "https://api.oanor.com/runoff-api/v1/rational" \
  -H "x-oanor-key: oanor_test_..."
await fetch("https://api.oanor.com/runoff-api/v1/rational", {
  headers: { "x-oanor-key": "oanor_test_..." }
});
$ch = curl_init("https://api.oanor.com/runoff-api/v1/rational");
curl_setopt($ch, CURLOPT_HTTPHEADER, ["x-oanor-key: oanor_test_..."]);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$out = curl_exec($ch);
import requests
requests.get(
    "https://api.oanor.com/runoff-api/v1/rational",
    headers={"x-oanor-key": "oanor_test_..."}
)

Example response

A real response from this endpoint, captured by the latest health check.

{
    "data": {
        "note": "Metric Rational Method: Q(m³/s) = C·i·A / 360, with rainfall intensity i in mm/h and catchment area A in hectares. C is the impervious-fraction runoff coefficient.",
        "inputs": {
            "units": "metric",
            "area_ha": 2,
            "intensity_mm_h": 50,
            "runoff_coefficient": 0.5
        },
        "peak_flow_l_s": 138.88889,
        "peak_flow_m3s": 0.13888889
    },
    "meta": {
        "timestamp": "2026-06-05T11:30:26.261Z",
        "request_id": "32fca715-a80d-46a3-9b43-c5f39be5b464"
    },
    "status": "ok",
    "message": "Rational method",
    "success": true
}