The summer of 2018 was one of the hottest and driest summers since the start of measurements by the Dutch weather service in 1900. This lead to forest fires, problems for farmers and extreme low water levels. The Rhine at Lobith recorded an all-time low water level and also the Ijssel an Meuse rivers recorded extreme low water levels. This caused many problems for everyone using the river water.

In this thesis, it has been investigated what in influence is of extreme low water levels on the strength and stability of navigation locks. This has been done in two phases. First, based on theory and small deterministic calculations, the most relevant failure mechanisms that can occur during drought have been selected. These are: Failure of the doors, piping and degradation of timber elements. Next, a probabilistic approach has been taken to see what the failure probability of a navigation lock is during extreme low water levels. These failure probabilities have been used in a risk analysis to estimate the probability of failure. It has been concluded that the risk of failure due to extreme low water levels is rather low.