Viking Helgrim · Portugal's River of Gold

How to read every number on this page

• "Water level now" is the authority's measured reading at the gauge named on this page. It uses centimetres from that gauge datumThe fixed zero point for a gauge's centimetre scale. It can sit above the riverbed.. It is a level, not a depth of water under your ship. It is not the depth of the navigable channelThe navigable channel where ships are meant to pass. either, and it is not your ship's draftHow deep a ship sits in the water. That depth sets how much water it needs underneath..
• "Water level the ship needs" — written WLSN at each end of its bold dashed line on the graphs — is Waterlogged's own arithmetic on published reference figures for that stretch and the draft we hold for this ship. It is our line, plainly labelled, and it is not the operator's decision to sail.
• The seasonal graph shows two different things. Left of the today line, solid blue shows the levels that were measured. Right of it, the dashed line shows the historical average for each date. It comes from what these gauges recorded on that date in past years. It is not a forecast of this autumn, and we do not draw one. We show it because that average keeps falling through October. That is useful to know before you sail.
• Where a line comes from the record — Budapest — the page says so. There is still no maintained-depth model published for the Hungarian Danube, so instead of guessing at one we set our level from what actually happened: in 35 years of readings, every cruise-season day below it fell within a disruption somebody documented at the time.
• Where no mark exists — Kienstock — we show the reading and the official marks and stop there.
• Where the numbers come from. Measured levels for Kaub, Cologne, Pfelling and Hofkirchen are verified daily averages from PEGELONLINEGermany's official service for live and archived federal waterway gauge readings.. They cover 2015–2026 and are topped up from the live archive. Budapest and Kienstock readings come through EuRISThe European River Information Services portal. It republishes official river data from member countries. and DoRISAustria's Danube River Information Services site for water levels and navigation notices.. For those two the solid line on the graph is drawn from our own recording of that live feed, which began in July 2026, so it is short and grows by a day each day; the graph says where it starts. The longer measured archive behind Kienstock is not ours to republish, so we do not draw it and we print no record sentence for it. For Budapest that changed on 17 August 2026: the General Directorate of Water Management gave us written permission to publish its own archive, and the average for each date now stands on 35 years of it. Each "normal for this date" uses a 31-day circular medianThe middle past value for that date. Half of past years were higher and half were lower. — the middle value, so half of past years were higher and half lower. The averages use 12 years of records on the German gauges, 35 years on Budapest and 25 years on Kienstock, from the projection engine's own doy_median_cm arrays. Record lines use an eleven-day window centred on the port's own date, across each gauge's whole archive. Budapest's levels come from Országos Vízügyi Főigazgatóság (OVF) / General Directorate of Water Management; where we work them into an average, those input data originate from the General Directorate of Water Management.
• Nothing here is a forecast. The trend and the graph describe measured moves that have already happened. We do not model your cruise and we do not give you a percentage chance of anything.