Evaluation of the resilience of inland waterway transport to increasing periods of low flow, following a Dynamic Adaptive Policy Pathway approach

Abstract

Although inland waterways (IWW) are considered one of the most reliable transport modes, it is very vulnerable to climate change, more than other transport modes such as rail and road transport. The inland waterway transport (IWT) performance strongly depends on the available water depth in the waterway, which is related to the river discharge. Due to climate change, it is expected that the number of days with low and extremely low discharges will occur more often during summer and autumn and that the absolute values of these low discharges will reduce. It is essential to maintain the current inland waterway transport capacity and promote a modal shift of transport by road and rail to IWT.

The Dynamic Adaptive Policy Pathway (DAPP) approach is used as a starting point for this research because the structure and steps cover objectives similar to the objective of this thesis. The essence of the DAPP approach is to develop an adaptive planning that can cope with deep uncertainties that a decision-maker has when the concerned time frame consists of many years in the future.

In step I of the DAPP approach, the objective of the inland waterway transport of dry-bulk and liquid-bulk is defined as performing better than railway transport during periods of low flow. This study considers the inland waterway transport of dry-bulk from Rotterdam to Duisburg and liquid-bulk transport from Rotterdam to Wesseling.
To assess if the objective is met, the transportation costs per ton kilometre of IWT are compared with the transportation costs per ton kilometre of railway transport. The condition for which the IWT value exceeds the railway transport value is called a tipping point.
To determine tipping points in steps II and III of the DAPP approach, a simulation model has been set up in the form of a stress test. The model concept chosen for the simulation is based on the OpenCLSim software package, a rule-based planning tool for cyclic activities.

No tipping points were found for the dry-bulk supply chain, indicating it performs better than railway transport during low flow periods based on transportation costs per ton kilometre. This also implies that no adaptation measures are needed to contribute to achieving the objective.
However, the liquid-bulk supply chain experiences tipping points between 35 and 65 consecutive days of low flow. Two adaptation measures have been analysed for the liquid-bulk supply chain to improve its performance during low flow periods. The first is an adjustment of the maintenance criterion of the waterway. This means that skippers know exactly where the bottlenecks are located so that they can sail around them. This results in a larger available water depth. The second adaptation measure is the availability of a diverse fleet, which means that extra vessels are deployed during low flow but idle during high flow. Adjusting the maintenance criterion results in an extension of the tipping points, and implementation of a diverse liquid-bulk fleet results in a situation where already tipping conditions occur after five days, based on transportation costs per ton kilometre. Based on KNMI ’06 climate scenarios covering a time horizon from 2001 to 2100, an estimation can be given on the timing of the tipping points.
As no tipping points were found for dry-bulk, it can be concluded that the supply chain is a more attractive transport modality than railway transport until 2100. The liquid-bulk supply chain is expected to experience its first tipping point around 2030, but this can be extended to 2072 by adjusting the maintenance criterion.