PhD research

In December 2019 Guy Dupuits obtained his PhD degree. Guy investigated the effect of including breaches in a flood defence system in the determination of the economically optimal flood risk. A breach in a flood defence will impact the flood risk of other flood defences in the same flood defence system. The economically optimal ratio between costs (flood defence reinforcements) and benefits (flood risk reduction) is altered by including breaches. 

Vincent Vuik defended succesfully his PhD-thesis on the Delft University of Technology in March 2019. He investigated how the concept ‘Building with Nature’ can be used for flood risk reduction. By constructing vegetated foreshores in front of flood defences, the wave attack on these dikes can be reduced. 

Furthermore, the following colleagues are currently working on different PhD studies:

In January 2020, Lieke Lokin, has started her PhD research on the topic “river dunes”. River dunes are relatively large bed forms. At high discharges these bed forms grow, at low discharges the dunes break down gradually. Growth and break down of the dunes lags behind the water depth during a flood wave, due to this hysteresis dunes in the tail of a flood wave dunes are higher than could be expected in equilibrium and during the rising stage dunes are lower. Dunes cause two problems for the river manager: first at high discharge they increase the bed roughness leading to higher water levels, second at low discharges the dunes become obstacles for waterborne transport. In her research Lieke strives to obtain a better insight into river dune dynamics, focusing on the falling stage of flood waves towards extreme low discharges and to implement this knowledge in a dune prediction model.

The new standard for the assessment of flood defenses in the Netherlands is based on flood probabilities, as imposed in the WBI2017. This standard method is less suitable for some flood defenses. For example, because the local circumstances do not match the scope of the models or because the models are based on conservative choices. We can see the effect of this in the levee assessments, where (sometimes incorrect) high flood probabilities are reported. In Guus Rongen his promotion research, it is investigated whether expert opinions (expert judgment) can better do justice to the local circumstances. For example, by getting a better picture of the uncertainties in soil conditions or loads, or by better estimating dependencies between parameter values, mechanisms or levee sections. The aim is to develop a new method to be able to estimate the probability of flooding in a more reliable way based on expert opinions. The TKI project is carried out in collaboration with Rijkswaterstaat, Deltares and HKV.

Ties van der Heijden researches the balancing capacity of the Dutch water system with respect to the electricity grid. Sustainable energy has a destabilizing effect on the grid. By controlling the demand for energy in a smart way, it can benefit the balance between supply and demand. Ties is looking at the available energy market- and balancing mechanisms, how they will develop over time, and how the water system (with all its uncertainties) can have a maximum positive impact on the energy transition.

Joost Pol studies how safety assessment of flood defences can be improved by including time-dependency in the failure processes, like the time required for backward erosion piping. In addition, he explores how different failure modes can interact with each other and how that affects the dike safety.