curl --request POST \
  --url https://api.iotools.cloud/v1/tool/manning-flow-calculator \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "unitSystem": "si",
  "channelShape": "rectangular",
  "bottomWidth": "2",
  "flowDepth": "1",
  "manningN": "0.013",
  "channelSlope": "0.5"
}
'

{
  "tool": "manning-flow-calculator",
  "tool_version": "1.0.2",
  "outputs": {
    "results": [
      {
        "metric": "Flow area",
        "value": "2.000 m²"
      },
      {
        "metric": "Wetted perimeter",
        "value": "4.000 m"
      },
      {
        "metric": "Hydraulic radius",
        "value": "0.500 m"
      },
      {
        "metric": "Velocity",
        "value": "3.427 m/s"
      },
      {
        "metric": "Discharge (flow rate)",
        "value": "6.853 m³/s"
      }
    ],
    "summary": "V = 3.43 m/s · Q = 6.85 m³/s"
  },
  "credits_used": 5,
  "credits_remaining": null
}