The effect of low water on loading capacity of inland ships

Prolonged periods of drought affect river discharges and cause water levels and available water depth to drop for extended periods of time. Low water depth has a major impact on the loading capacity of inland ships, and as a consequence on the transport capacity of the overall waterborne supply chain. Individual ship owners have detailed knowledge on how much the draught of their ship and the associated cargo weight should be reduced to adapt to low water. These parameters are even adjusted as a function of environmental circumstances (e.g. composition of the riverbed) and type of cargo. This detailed knowledge is, however, not accessible at an aggregated level to assess the effects on the overall transport capacity of an inland waterway transport network. Based on a range of field observations and information collected from individual ships, this article introduces a general model to define the effect of low water constraints on the deadweight and payload of inland ships, for which only the type, length, and beam of the vessel serve as mandatory input. Availability of a general model of the capacity reducing effect of lowered water depth is important for the design and operation of robust transport chains on the one hand, and for the optimisation of fairway maintenance and long-term infrastructure development on the other.