Abstract
Abstract. Traditionally, navigation-related forecasts in central Europe cover short- to medium-range lead times linked to the travel times of vessels to pass the main waterway bottlenecks leaving the loading ports. Without doubt, this aspect is still essential for navigational users, but in light of the growing political intention to use the free capacity of the inland waterway transport in Europe, additional lead time supporting strategic decisions is more and more in demand. However, no such predictions offering extended lead times of several weeks up to several months currently exist for considerable parts of the European waterway network. This paper describes the set-up of a monthly to seasonal forecasting system for the German stretches of the international waterways of the Rhine, Danube and Elbe rivers. Two competitive forecast approaches have been implemented: the dynamical set-up forces a hydrological model with post-processed outputs from ECMWF general circulation model System 4, whereas the statistical approach is based on the empirical relationship (teleconnection) of global oceanic, climate and regional hydro-meteorological data with river flows. The performance of both forecast methods is evaluated in relation to the climatological forecast (ensemble of historical streamflow) and the well-known ensemble streamflow prediction approach (ESP, ensemble based on historical meteorology) using common performance indicators (correlation coefficient; mean absolute error, skill score; mean squared error, skill score; and continuous ranked probability, skill score) and an impact-based evaluation quantifying the potential economic gain. The following four key findings result from this study: (1) as former studies for other regions of central Europe indicate, the accuracy and/or skill of the meteorological forcing used has a larger effect than the quality of initial hydrological conditions for relevant stations along the German waterways. (2) Despite the predictive limitations on longer lead times in central Europe, this study reveals the existence of a valuable predictability of streamflow on monthly up to seasonal timescales along the Rhine, upper Danube and Elbe waterways, and the Elbe achieves the highest skill and economic value. (3) The more physically based and the statistical approach are able to improve the predictive skills and economic value compared to climatology and the ESP approach. The specific forecast skill highly depends on the forecast location, the lead time and the season. (4) Currently, the statistical approach seems to be most skilful for the three waterways investigated. The lagged relationship between the monthly and/or seasonal streamflow and the climatic and/or oceanic variables vary between 1 month (e.g. local precipitation, temperature and soil moisture) up to 6 months (e.g. sea surface temperature). Besides focusing on improving the forecast methodology, especially by combining the individual approaches, the focus is on developing useful forecast products on monthly to seasonal timescales for waterway transport and to operationalize the related forecasting service.
Highlights
Competitive transport systems are vital for Europe’s prosperity and its economic growth and the demand, especially for freight transport, will significantly increase within the coming years
Despite all differences amongst the gauges or waterways, the overall conclusion of the Ensemble streamflow prediction (ESP) and reverse-ESP experiments is that for the majority of initialization months and lead times, the mean squared forecast error is dominated by the meteorological forcing
None of the approaches tested consistently outperformed the ESP-based method currently applied operationally
Summary
Competitive transport systems are vital for Europe’s prosperity and its economic growth and the demand, especially for freight transport, will significantly increase within the coming years. Besides safeguarding a high degree of efficiency, accessibility and safety, today’s European and national transport policy is clearly oriented towards sustainable and energy-efficient transport systems In this regard, the importance of inland waterway transport (IWT) will further increase, because it is an environmentally friendly and safe mode of transport, which still has plenty of spare capacity (European Commission, 2001). Besides the low transport velocity and the comparatively low network density, the natural variability of the fairway conditions and the availability along substantial parts of the European waterway network pose the main weaknesses In this respect, low streamflows, floods and river ice are the significant hydrological hazards concerning IWT in central Europe. During low-flow situations, additional (small) ships are needed to handle the same amount of cargo as during periods with mean water-level conditions This causes increasing transport costs (see Fig. 1). Low-flow situations increase the danger of ship grounding and ship-to-ship collisions due to a reduced depth and width of the affected fairways
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
