As well as Lake Constance, the waterways of the Rhine and the Danube – which are vital for freight transport – have been particularly hard hit by the ongoing record-low water levels. Water levels there are continuing to fall. In Kaub on the Middle Rhine, a single-digit figure was reported today for the very first time: at midday, there were just eight centimetres between the lower end of the gauge and the water level.
- Water levels: What they reveal and what they don’t
That does not, however, mean that the Rhine is only a hand’s breadth deep in this section – even if the situation is not much better. The depth of the navigable channel is the decisive factor – and this must first be calculated, taking the water level into account.
Rhine: Equivalent water level
On the Rhine, a statistical reference value for the water level is also required when calculating the current navigable channel depth: the Equivalent Water Level (GIW). This is based on the water levels of discharges along the course of the river that are classified as equivalent.
They are redefined every ten years for each gauging station (most recently in 2022) and can vary significantly from one another; for example, 237 cm in Speyer, 155 cm in Mannheim and 68 cm in Worms.
At the same time, efforts are being made to guarantee minimum navigation channel depths, which are based on the GIW. There are differences here too. According to these figures, the depth should be at least 2.50 m between Krefeld and Koblenz, but only 2.10 m from Koblenz to St. Goar. Using these two additional figures, it is now possible to calculate the current navigation channel depth.
Example of the River Rhine at Andernach:
- Target channel depth for the Krefeld–Koblenz stretch: 250 cm
- + Daily water level at Andernach (example daily reading): 323 cm
- - Equivalent water level (GlW) at Andernach: 91 cm
- = Load depth: 482 cm
Current (14 August 2026):
- Target channel depth for the Krefeld–Koblenz stretch: 250 cm
- + Daily water level at Andernach (current): 8 cm
- - Equivalent water level (GlW) at Andernach: 91 cm
- = Load depth: 167 cm
Danube: Regulated low water level
On the Danube, a statistical reference value known as the regulated low-water level (RNW) has also been introduced. For the sake of completeness, here is the definition: the RNW corresponds to the average water level on at least 94 per cent of all ice-free days. In addition, there are minimum navigable channel depths relative to the RNW: for example, 2.90 m from Kelheim to Straubing and, further on, 2.00 m as far as Vilshofen.
Of course, recreational skippers have an easier time of it on both rivers than professional skippers. This is because, unlike a small cabin boat, the draught of a cargo vessel varies considerably depending on the amount of cargo. When the vessel is at rest, this is referred to as the unloaded draught. However, when it picks up speed, the stern sinks deeper into the water. This draught, combined with the unloading draught, gives the total draught. The skipper must therefore calculate precisely how much he is permitted to load at different water levels. It is important that he does not forget the famous ‘hand’s breadth’ beneath the keel: the so-called ‘floatation water’.
Example from the Danube at Hofkirchen:
- Target channel depth between Deggendorf and Vilshofen: 200 cm
- + Daily water level at Hofkirchen (example daily reading): 367 cm
- - Regulated low-water level (RNW) Deggendorf-Vilshofen: 207 cm
- = Load depth: 360 cm
Current (14 August 2026):
- Target channel depth between Deggendorf and Vilshofen: 200 cm
- + Daily water level at Hofkirchen (current): 131 cm
- - Regulated water level (RNW) at Deggendorf-Vilshofen: 207 cm
- = Load depth: 124 cm
Between the Elbe and the Oder
Skippers have an easier time of it on the eastern waterways, particularly on the Elbe, where in recent years they have had to contend with extremely low water levels even more frequently than elsewhere.
There, for the sections of the waterway between Schöna and Lauenburg, it is no longer the water levels that are reported, but the navigable channel depths – and, of course, recreational boaters benefit from this too. On the other waterways between the Elbe and the Oder too – such as the Lower Havel Waterway, which is reserved for recreational craft – a pragmatic approach is taken, with reports provided, if not of the navigable channel depths, then at least of the maximum draught or unloading depths.
On other inland waterways, particularly those that are regulated, it is easier to comply with the specified minimum navigable depths. Nevertheless, even recreational skippers would be well advised to find out in advance how and where water levels in a particular area are measured and reported.
Current water levels for all German inland waterways, together with forecasts, are available online on the website of the Federal Waterways and Shipping Administration (WSV) at www.elwis.de.
- Water levels: What they reveal and what they don’t
Christian Tiedt
Editor Travel