VE-I-1 + 2: Flood closures and low water restrictions on the Rhine
2023 Monitoring Report on the German Strategy for Adaptation to Climate Change
Table of Contents
VE-I-1: High-water closures to shipping on the Rhine
Over the past 30 years or so, high-water closures have affected Rhine shipping, especially on the Upper Rhine. In 1999, 2016 and 2021 inland shipping was unable to navigate the Upper Rhine for an extended period owing to high water.
The illustration VE-I-1 entitled ’High-water closures on the Rhine’ contains a grouped bar chart which shows closures to Rhine shipping owing to high water when the HSW was reached or exceeded at the gauges of Maxau (Upper Rhine), Kaub (Middle Rhine) and Cologne (Lower Rhine). The number of high-water closures is illustrated, covering the period from 1970 to 2010, and from 2011 to 2021 the aggregated duration of closures in days with reference to quarter-hourly measurements of water levels is shown. There is no significant trend for any of the three river sections. The values fluctuate distinctly from year to year. The highest value was recorded on the Upper Rhine with just short of 34 days in 1999. The Lower Rhine section had the lowest amount of closures.
VE-I-2: Low-water restrictions to shipping on the Rhine
Prolonged low-water phases have repeatedly placed incisive restrictions on shipping in the Upper, Middle and Lower Rhine sections. These phases were particularly long-lasting in 2018. This was typically caused by summer drought and heat. In some cases, the impacts lasted well into December. Regarding the Lower Rhine, low-water restrictions clearly indicate a trend that has been increasing significantly since 1997.
The illustration entitled VE-I-2 ’Low-water restrictions on the Rhine’ is a grouped bar chart showing the number of days for the period of 1997 to 2021 when the equivalent water level values at the gauges of Maxau (Upper Rhine), Kaub (Middle Rhine) and Ruhrort (Lower Rhine) were not attained. Non-attainment of the equivalent water level signifies restrictions on the draught of vessels navigating the Rhine. There is no significant trend discernible for the Upper Rhine or the Middle Rhine. However, the Lower Rhine shows a significant rising trend regarding the number of those days. The values fluctuate distinctly from year to year. When low-water restrictions arise, this usually affects all three sections of the Rhine, although individual sections may be affected in different degrees. By far the highest values were recorded in 2018, with 80 days on the Upper Rhine, 107 days on the Middle Rhine and 128 days on the Lower Rhine. Other years with comparatively numerous days of draught restrictions always showed values of less than 50 days.
Extended low-water phases have very severe impacts
In meteorological and hydrological terms, 2018 was an extraordinary year which demonstrated how dependent Rhine navigation is on the weather and on weather patterns. Great amounts of precipitation fell in the mild month of January, mostly as rain, making streams and rivers swell immediately. The Rhine’s water levels exceeded the relevant floodwater marks so that shipping had to be suspended temporarily on all sections of the river. As the year progressed, temperatures remained high whereas precipitation largely failed to materialise until the beginning of December. On the Rhine, this led to an unusually long low-water phase in late summer and autumn which was associated with draught restrictions being imposed on inland shipping. Consumers suffered the consequences in terms of rising fuel prices. As it was no longer possible for tank barges to navigate the Rhine fully laden, and because around the same time a Bavarian refinery stopped production for an extended period, fuel sold at filling stations in southern Germany became scarce and expensive.160 In 2018, the total freight carried by Germany’s inland vessels was down by approximately 25 million tonnes compared to the previous year, representing a decline by 11.1 %.
The Rhine is Germany’s most important inland waterway. The river enables cost-effective and environmentally sound transport of goods, facilitates imports and exports via North Sea ports in Belgium and the Netherlands, and it links important industrial centres within Germany161. More than three quarters of goods transported by Germany’s inland shipping are conveyed via the Rhine162. Whenever high or low water levels lead to restrictions imposed on Rhine shipping, this can entail – in some cases considerable – impacts on individual companies or on entire production chains and delivery chains. Primarily solid and liquid bulk commodities are transported on waterways. These are difficult to re-allocate to other transport carriers, while some of these commodities can only be re-allocated to some extent.
The rules governing Rhine shipping are contained in the pertinent police regulation (Rheinschifffahrtspolizeiverordnung). According to this regulation, ships will have to reduce their speed and must be equipped with a radiotelephone installation in cases where the water level exceeds the high-water mark I. In cases where the HSW is exceeded, the sections affected will have to be closed to shipping. The closures imposed in late winter and spring of 1999 were particularly incisive, when the Upper Rhine was closed to shipping for several weeks owing to two high-water phases. In 2021 there were extended closures on the Upper Rhine owing to abundant falls of rain, first at the end of January, and later in July. On the Middle and Lower Rhine, there have been only brief closures since 2000 which, in most cases, were rescinded after less than a week. So far no significant trends towards more high-water closures have been discerned for the Rhine.
In cases where water levels fall below a threshold value set for a specific section of the river, at which the target depth of the navigation channel is still safely given (in the Rhine this threshold is defined by the so-called equivalent water level) shipping is usually still possible. However, this involves various degrees of restrictions subject to the extent of non-attainment of the mark and according to the size and construction of the inland shipping vessel. On the Rhine such low-water phases usually occur in late summer from August until October. However, in recent years there has been an increase in the frequency of low-water phases lasting well into November or December. This is true for 2011, 2015 and latterly especially in 2018. For the Lower Rhine, the time series starting in 1997 shows a significant increase in low-water restrictions.
The risk analysis entitled ‘Drought’163 carried out at Federal Government level in 2018, spells out the potentially grave impacts of long-lasting low water levels on inland navigation. The simulated scenario of the risk analysis – an at times extreme drought phase lasting six years – shows long-lasting and significant low-water phases on the Rhine. In such cases, inland shipping is subject to restrictions while in some stretches of the river, it has to be temporarily suspended. In southern Germany and in Switzerland, this can lead to supply bottlenecks regarding bulk commodities. Enterprises in various industries can suffer commercial losses: transport costs rise, while in some cases production has to be curbed or suspended owing to lack of raw materials; and there are problems with the despatch of finished products. Likewise, there can be restrictions and price rises with regard to the supply of power, heat and fuel, owing to constraints in the transport of coal, heating oil and mineral oil products. 2018 was a year which provided graphic examples of the potential consequences entailed by low water levels.
160 - BfG – Bundesanstalt für Gewässerkunde (Hg.) 2019: Das Niedrigwasser 2018. Koblenz, 22 pp. https://doi.bafg.de/BfG/2019/Niedrigwasser_2018.pdf
161 - Deutscher Bundestag (Hg.) 2019: Bericht zur Risikoanalyse im Bevölkerungsschutz 2018. Unterrichtung durch die Bundesregierung, Drucksache 19/9521. Berlin, 144 pp. https://dserver.bundestag.de/btd/19/095/1909521.pdf
162 - StBA – Statistisches Bundesamt (Hg.) 2022: Güterverkehrsstatistik der Binnenschifffahrt. Fachserie 8 Reihe 4, Ausgabe Dezember 2021. Tabellenblätter 1.1 und 4.1. https://www.statistischebibliothek.de/mir/receive/DEHeft_mods_00141101
163 - Deutscher Bundestag (Hg.) 2019, cf. endnote no. 161
