A framework for the impact assessment of low discharges on the performance of inland waterway transport

Abstract

Inland waterway transport (IWT) is one of the three main modalities for inland transport of dry, liquid and containerized cargo. As IWT performs well on cost-competitiveness, environmental friendliness, and congestion-related issues, authorities strive to shift freight transport from road to water. Inland waterway connections, however, are vulnerable to the growing impact of climate change. A combination of higher temperatures and more extreme seasonal differences in precipitation is expected to increasingly impact river discharge in the future. In summer, this will result in low water events happening more frequent and more intense. The effects of climate change on IWT could result in a reduced annual transport capacity, thereby weakening the reputation of IWT and increasing the costs of cargo shipment. The objective of this research is to provide more insight into the consequences of climate change-induced low discharges on the performance of IWT and to assist in making justified adaptation decisions. During this research, an IWT performance model has been developed that is capable of studying the capacity and vulnerability of the inland waterway system to low water depths, and simultaneously can be used to propose measures to strengthen the position of IWT. To assess the quality of the logistic simulations, the model has successfully been subjected to a number of validity tests. Consequently, the model was calibrated on two parameters that have a high uncertainty and a significant impact on the simulation. After calibration, the model shows correlation coefficients of r=0.794 and r=0.921 so that it can be concluded that the results of the IWT performance model are relatively accurate with reality. Daily projections of the water depth on the Rhine are obtained by extrapolation of the representative, dry year 1976 with two climate scenarios to the year 2050. The water depths encountered have been compared to the base scenario. To put into perspective these impacts, a model run for the reference scenario of 2018 has been incorporated in the comparison. It follows from this thesis that low discharges, in combination with navigational restrictions, could cause substantial losses for the IWT in 2050 in terms of transported cargo and transport costs. Following from literature, the accurate modelling of IWT should include various local effects that follow from regulations, fleet composition or waterway characteristics. This research is the first study on the impact of low water depths on the IWT performance that does not take the load factor as the only variable but that includes other network parameters as the active fleet size and the number of trips to provide a comprehensive picture of the IWT performance in periods of low discharge.