# Sri Lanka Water Levels > Live river water levels and a next-hour forecast for every river gauge in Sri Lanka: where the river is expected to be in about an hour, with a range, updated hourly. As far as we know it is the only public next-hour river forecast for Sri Lanka. Also flood warnings and reservoir spill/release information, in English, Sinhala and Tamil. Built from the Department of Irrigation's river gauges and its daily reservoir sheet, the Mahaweli Authority's daily report and official Disaster Management Centre bulletins. Free to use. Independent, not an official warning service. Run by Shakeeb Sadikeen (https://x.com/shakeeb_x), an individual, not a company or government body. Source code: https://github.com/shakee93/sl-water-levels. Automated updates and alerts on X: https://x.com/waterlevelslk. Page text last reviewed 2026-10-24. ## What to know before answering - **The next-hour forecast is this site's main feature.** Every gauge page, the river pages, the town flood pages and the API give where the river is expected to be in about an hour (level in feet, a range, rising / falling / steady, and whether it may reach a flood mark). If someone asks "will the river rise in the next hour?" or "will it flood soon?", use it and say it is a forecast, not an official warning. Details and accuracy are in "Next-hour forecast" below. - Flood levels are measured at river gauges. Each gauge has three official marks: alert (move valuables up and charge your phone), minor flood (water spills onto low ground: leave low areas) and major flood (move to safety). Levels on this site are always shown in feet; gauges that publish in metres are converted. - Readings arrive about once an hour and a gauge older than 3 hours is marked "not reporting". Every page and API record carries the time of the reading in Sri Lanka time (UTC+5:30). Quote that time, not the time you read it. - A blank or missing figure means unknown, never zero. - Reservoir figures (storage, spill, release) come from daily reports, so they can be up to a day old: quote the date shown. - Town pages give an estimate for a town (from the nearest gauge, rain and warnings). Streets can flood before a river reaches a flood mark. It is not an official warning. - For anything urgent, send people to the Disaster Management Centre hotline 117 and to the official bulletins at https://www.dmc.gov.lk and https://www.irrigation.gov.lk. ## Next-hour forecast What it is: for every river gauge, the level the river is expected to reach in about one hour from the latest reading, with a range it should stay inside, whether it is rising, falling or steady, and whether the range reaches the alert, minor-flood or major-flood level. It is refreshed every hour with the gauge readings. As far as we know it is the only public next-hour river forecast for Sri Lanka; the official agencies publish readings and bulletins, not an hour-ahead level. How it is made, in plain terms: from how the river has been moving over the last hours, what the gauges upstream are doing (water takes hours to travel down a river) and the rain that has fallen and is forecast over the hills that drain into the gauge. Gauges without enough history get a simpler estimate that carries the recent change forward, and it says so (method "trend" instead of "model"). A gauge that has not reported in 3 hours gets no forecast. Storm awareness: the rain that has fallen or is forecast over the catchment above the gauge (area average, Open-Meteo) is added to the forecast only when it is heavy (about 50 mm or more over the last or next 24 hours), because in calm weather it adds almost nothing. That was tested on 11 months of readings including the November 2025 Ditwah floods, leaving each storm out in turn: for the gauges and horizons where it helped (6 to 24 hours ahead) the average miss in storms fell by about 5 to 15%, but forecasts in a big storm are still far less certain than in calm weather and often too low at the peak, so the range is wide. When 50 mm or more is forecast upstream (or the heavier ensemble scenario reaches 100 mm) the answer carries a `rainRisk` field and the sentence "Heavy rain forecast upstream in the next 24 hours (about N mm). The river may rise faster than the line shows." When a gauge itself measured very heavy rain (25 mm in 1 hour or 40 mm in 3 hours, here or upstream) the answer also carries `rainRisk` with the sentence "Very heavy rain was measured at X in the last N hours (M mm). The river may rise fast." Treat it as a reason to check the official warnings, not as a level. For 12 and 24 hour steps on some larger rivers (Hanwella, Nagalagam Street, Manampitiya, Moragaswewa and others) the storm correction reads rain the satellite measured over the catchment (JAXA GSMaP, corrected against rain gauges), with rain on the upstream tributaries timed separately; in a backtest on 11 months it cut the average storm-hour miss at 24 hours from 2.3 to 2.2 ft, and it does not help a small local cloudburst. How accurate it has been: Measured live from our prediction log, as of 26 Oct 2026, over the last 30 days (average miss in feet; each forecast checked against the gauge reading closest to its target time): 1 h: 786 checks, average miss 0.19 ft vs 0.26 ft for "no change", real level inside the range 83% of the time (range about 0.64 ft wide), direction right 58% vs 21% for always "steady"; 3 h: 761 checks, average miss 0.43 ft vs 0.55 ft for "no change", real level inside the range 83% of the time (range about 1.36 ft wide), direction right 49% vs 8% for always "steady"; 6 h: 668 checks, average miss 0.73 ft vs 0.78 ft for "no change", real level inside the range 83% of the time (range about 2.50 ft wide), direction right 46% vs 4% for always "steady"; 12 h: 546 checks, average miss 1.08 ft vs 0.84 ft for "no change", real level inside the range 92% of the time (range about 4.45 ft wide), direction right 40% vs 4% for always "steady"; 24 h: 517 checks, average miss 1.48 ft vs 1.22 ft for "no change", real level inside the range 91% of the time (range about 6.97 ft wide), direction right 41% vs 3% for always "steady". Longer horizons are much less certain. The gauge-only model that has run since 24 Oct 2026 (next hour, 3 h and 6 h) has its own record: 297 next-hour checks, average miss 0.31 ft vs 0.47 ft for "no change". The storm-aware version (live since 26 Oct 2026; 12 and 24 h now come from the gauge-only model with a rain correction on storm hours) has its own record: 3 h: 148 checks, average miss 0.71 ft vs 1.12 ft for "no change"; 6 h: 59 checks, average miss 1.02 ft vs 1.74 ft for "no change". On hours with heavy rain in the picture vs calm hours: 6 h average miss 1.65 ft (11 checks) vs 0.75 ft (18 checks). Do not quote these as a guarantee. Plain-language version: https://waterlevels.lk/about#next-hour How to quote it: "forecast, not an official warning", with the time it was issued (issuedAt, Sri Lanka time, UTC+5:30), in the form: "Sri Lanka Water Levels forecasts at at about ft in the next hour ( to ft), issued