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.

The summer and autumn of 2018 showed the negative effects of both low-flow conditions and bed degradation over the last century on the river functions of the Dutch Rhine. These resulted in record-breaking water levels, extreme low navigation depth and subsequently nautical problems. As climate change will increase the inter-annual variability of the Rhine’s discharge pattern, low-flow conditions are likely to occur more often, reinforcing the above-mentioned impacts on nature and navigation. Sediment management is considered as a sustainable way to counteract the bed degradation. To justify an investment in a large scale nourishment, the impact of a nourishment on the river functions has to be compared with the result of a reference situation without nourishment. This study aims to develop a methodology that evaluates the future performance of rivers functions accounting for the autonomous trends (bed level and climate changes) and provides insights in the functional performance and cost effectiveness of river interventions. The methodology enables the assessment of the impact of the trends on the river system without intervention. It appears that the navigational efficiency is decreased enormously by climate change en bed erosion, which will increase transportation costs. Based on these indicative analysis a nourishment is predicted to be cost effective by improving both the navigational efficiency and counteracting dehydration of the floodplains.