Postdoc position in Physical Geography: High-resolution modelling of groundwater flow as control on dike failure (1.0 FTE)

The Department of Physical Geography seeks a Postdoc for the project 'Improvement of dike failure probability estimates using knowledge of the subsurface', which is part of the research programme All-Risk, funded by STW. The project contributes to the Utrecht University focus area 'Future Deltas'.

In 2014 the Dutch Flood Protection programme adopted a new probabilistic risk approach for the management of the flood defences. Protection standards are expressed as flooding probabilities of polder areas, implying that multiple failure mechanisms for all dike sections within a dike ring must be considered, and then combined to assess the overall flooding probability. The All-Risk programme provides the scientific interdisciplinary support for this new approach, through collaboration of Dutch universities, Deltares, Rijkswaterstaat, Water Boards, and the private sector. The impact of All-Risk will also be international through collaborations with universities in e.g. Houston, Tokyo and Leipzig.

Dike failure due to various mechanisms (piping, undercutting by deep channel scour, deformation due to soil subsidence, basal slip) are related to the sub-surface and groundwater pressures, which show great spatial heterogeneity. Current predictive models rely on over-simplified average subsurface properties or parameterized process descriptions, resulting in potentially oversized designs, which need to be improved. The high-resolution geological databases of Utrecht University and TNO-Geological Survey of the Netherlands well document the subsurface heterogeneity, which shows systematic patterns associated with the processes that formed the deposits in the past.

The Postdoc project will focus on the efficient incorporation of subsurface characteristics into 3D groundwater modelling. The final goal is to develop tools that enable a rapid assessment of groundwater-related failure risk of dike stretches. To this end the postdoc will (i) create a tool to automatically generate a 3D-groundwater flow and stability model for a given dike stretch; (ii) develop methods to parameterize relevant subsurface and hydrological characteristics to be used in the 3D groundwater and stability model using available geological databases; (iii) perform quantitative model calculations regarding groundwater flow and erosion as function of subsurface architecture, dike geometry, and water levels for various dike stretches, (iv) explore the utility of geophysical methods (e.g. in-situ and airborne EM and surface temperature sensing to improve model parameterization by model-data fusion, and (iv) explore uncertainties and relevant scenarios in line with those used in water practice.

The Postdoc will work closely together with a PhD candidate at Utrecht University who focusses on schematisation and prediction of subsurface characteristics from a geological and geomorphological perspective and a PhD candidate at Delft University of technology who focusses on using geophysical methods in dike failure risk assessment.  The candidate will also collaborate with the experts and stakeholders in Deltares, TNO-Geological survey of the Netherlands, Rijkswaterstaat, Water Boards, and the Foundation for Applied Water Research (STOWA).