Kaub gauging station information

50°5.126′N 7°45.898′E / 50.085433°N 7.764967°E / 50.085433; 7.764967

The Kaub gauging station (German: Pegel Kaub, Kauber Pegel) is a stream gauge located on the Rhine river in the German city of Kaub. It is a "decisive" water level measurement site for the Rhine, as Kaub is located at the shallowest part of the Middle Rhine and ships with freight from North Sea ports have to pass Kaub on their way to the industrial southwest of Germany.^[1] The gauge level does not directly correspond to the actual depth of the river (zero level is not at the riverbed); instead, as is the case with most Rhine gauges, the actual depth of the navigation channel is defined as:^[2]

Gauge value + Ideal depth of the navigation channel (1.9 m) − Equivalent water level (0.78 m)

For example, a gauge level of 60 cm corresponds to an actual navigation depth of 0.60 + 1.90 - 0.78 = 1.72 m.^[2]

When the level at the gauge reaches the low 75 cm mark, the reduced possible load means that four times as many container barges are required to transport the same volume of goods when compared to the high (250 cm) level.^[3] The river becomes nearly impassable for freight at a gauge level of 35 cm (there is no hard lower limit).^[4] Navigation is prohibited above the high water mark II (6.40 m).