KAI-River · Rating Curve Studio · live preview
From gaugings to a rating curve, with its uncertainty
A rating curve turns the water level you can log every few minutes into the flow you need for forecasts, permits and designs. Fit one to your gaugings, see how far each gauging sits from it, leave out the odd ones, and take away the rating table and your level record converted to flow.
1 · Gaugings
Paste or upload stage–discharge gaugings: a header naming date, stage (m) and discharge (m³/s) in any order, or three columns without a header. Everything stays in your browser.
Example: Potomac River near Washington, D.C., Little Falls. U.S. Geological Survey, Water Data for the Nation (field measurements), public domain. Station page
2 · The rating
Q = 727.8 · (h − 0.633)^1.735
- Scatter of gaugings (1 s.e.)
- ±4.9 %
- Gaugings used
- 72
- Gauged range
- 0.75–3.62 m
- Flagged
- 3
Orange points lie more than two standard errors from the curve. Click a point (or use the table) to leave it out of the fit; click again to bring it back.
3 · Each gauging against the curve
| Date | Stage, m | Q, m³/s | From curve | Use |
|---|---|---|---|---|
| 2010-09-22 | 0.777 | 28.60 | +14.0 % | |
| 2012-06-28 | 0.893 | 68.24 | -2.7 % | |
| 2013-09-04 | 0.991 | 122.9 | +0.6 % | |
| 2014-02-24 | 2.274 | 1801 | +4.8 % | |
| 2014-02-25 | 2.076 | 1467 | +6.7 % | |
| 2014-02-27 | 1.716 | 897.6 | +7.5 % | |
| 2014-05-17 | 3.508 | 4389 | -3.5 % | |
| 2014-09-11 | 0.872 | 58.33 | -3.7 % | |
| 2015-03-12 | 2.048 | 1390 | +4.7 % | |
| 2015-08-05 | 0.908 | 74.76 | -3.3 % | |
| 2015-08-12 | 0.869 | 55.78 | -5.8 % | |
| 2015-08-12 | 0.869 | 60.31 | +1.8 % | |
| 2015-08-19 | 0.847 | 48.42 | -3.1 % | |
| 2015-12-07 | 1.305 | 370.9 | +1.7 % | |
| 2016-02-05 | 2.947 | 3143 | +0.8 % | |
| 2016-02-06 | 2.393 | 2013 | +3.8 % | |
| 2016-05-25 | 1.747 | 931.6 | +6.2 % | |
| 2016-08-31 | 0.832 | 46.44 | +5.4 % | |
| 2016-10-21 | 0.896 | 75.89 | +6.1 % | |
| 2017-01-04 | 1.119 | 211.8 | +1.9 % | |
| 2017-01-26 | 2.048 | 1314 | -1.1 % | |
| 2017-03-29 | 1.216 | 288.8 | +1.3 % | |
| 2017-05-17 | 1.628 | 744.7 | +3.3 % | |
| 2017-08-02 | 1.332 | 393.6 | +0.8 % | |
| 2017-10-03 | 0.805 | 33.70 | -1.4 % | |
| 2017-12-19 | 0.881 | 62.58 | -3.1 % | |
| 2018-04-19 | 2.124 | 1376 | -5.4 % | |
| 2018-05-21 | 2.707 | 2628 | +1.9 % | |
| 2018-06-05 | 3.621 | 4417 | -9.1 % | |
| 2018-11-01 | 1.308 | 373.8 | +1.7 % | |
| 2018-12-17 | 3.517 | 4304 | -5.8 % | |
| 2019-07-02 | 1.030 | 141.6 | -3.2 % | |
| 2019-07-02 | 1.030 | 143.8 | -1.6 % | |
| 2019-08-29 | 0.985 | 119.5 | +0.7 % | |
| 2019-08-29 | 0.985 | 119.5 | +0.7 % | |
| 2019-09-18 | 0.856 | 49.55 | -7.7 % | |
| 2019-09-25 | 0.832 | 40.78 | -7.4 % | |
| 2019-11-21 | 0.896 | 70.51 | -1.4 % | |
| 2020-04-29 | 1.676 | 792.9 | +1.3 % | |
| 2020-06-10 | 1.204 | 288.8 | +5.1 % | |
| 2020-10-06 | 0.945 | 89.76 | -6.7 % | |
| 2021-03-03 | 2.548 | 2212 | -1.5 % | |
| 2021-06-25 | 1.039 | 158.3 | +4.1 % | |
| 2021-08-10 | 0.820 | 38.23 | -3.3 % | |
| 2021-10-19 | 0.948 | 99.11 | +1.3 % | |
| 2022-03-02 | 1.366 | 436.1 | +2.8 % | |
| 2022-05-09 | 2.972 | 2917 | -8.2 % | |
| 2022-06-16 | 1.021 | 140.2 | -0.3 % | |
| 2022-08-23 | 0.908 | 73.91 | -4.4 % | |
| 2022-10-06 | 1.109 | 200.2 | -0.1 % | |
| 2022-10-26 | 0.863 | 58.05 | +2.5 % | |
| 2023-01-03 | 1.253 | 331.3 | +4.5 % | |
| 2023-04-27 | 0.985 | 108.2 | -8.8 % | |
| 2023-06-09 | 0.863 | 54.65 | -3.5 % | |
| 2023-06-09 | 0.863 | 54.09 | -4.5 % | |
| 2023-08-02 | 0.820 | 37.10 | -6.1 % | |
| 2023-08-21 | 0.786 | 27.81 | -0.2 % | |
| 2023-08-29 | 0.750 | 17.47 | -0.0 % | |
| 2023-10-24 | 0.811 | 37.66 | +3.8 % | |
| 2024-01-30 | 2.451 | 1951 | -4.9 % | |
| 2024-06-26 | 0.820 | 43.89 | +11.0 % | |
| 2024-07-31 | 0.802 | 34.26 | +3.4 % | |
| 2024-10-15 | 0.963 | 102.2 | -3.6 % | |
| 2025-02-27 | 1.170 | 256.6 | +3.8 % | |
| 2025-05-15 | 3.331 | 4248 | +4.3 % | |
| 2025-05-30 | 2.048 | 1396 | +5.1 % | |
| 2025-07-30 | 1.055 | 162.5 | -0.0 % | |
| 2025-09-05 | 0.832 | 43.89 | -0.3 % | |
| 2025-11-26 | 0.872 | 58.90 | -2.7 % | |
| 2026-04-07 | 1.134 | 220.9 | +0.8 % | |
| 2026-08-11 | 0.936 | 87.78 | -4.0 % | |
| 2026-10-07 | 0.826 | 46.16 | +10.5 % |
4 · Use it
Turn a level record into flow
Paste time and stage (two columns). Values outside the gauged range are marked as extrapolated.
Method: least squares on log discharge, Q = a·(h − h0)^b, with the stage of zero flow searched below the lowest gauging; the band is the scatter of single gaugings about the curve (95 %). Check shifts after floods and keep the gauge datum unchanged across the gaugings you fit.