The Haringvliet Estuary in the western part of the Netherlands was closed off in 1970 by a series of locks as part of the Delta Works for coastal protection. After the closure, the Haringliet became a freshwater body and was used as a source of freshwater for consumption and agriculture. Since 2018, the operating policy of the Haringvliet locks has changed and some locks are opened not only to discharge the river to the sea but also to allow limited inflows from the sea during flood tides to enhance the ecosystem functions of the estuary. The incoming saltwater should ideally be flushed out during the subsequent ebb tide. However, the Haringvliet Estuary has several bathymetric depressions that can store large amounts of saltwater, which, depending on the flow conditions, may not mix easily with the freshwater pulses due to the density differences. In such cases, the freshwater flows over the saltwater for extended periods of low river discharge and the flushing of the saltwater from the scour holes may occur in undesirable periods (e.g., due to wind-driven flow recirculation when the locks are closed), affecting the freshwater intakes.

This EngD project will investigate the mixing processes between saltwater that is trapped in large bathymetric depressions and freshwater that flows towards the depression, with the Haringvliet Estuary as a case study. The aim of the project is to determine the flow conditions that lead to flushing of the trapped saltwater from the bathymetric depressions in the Haringvliet Estuary and design a strategy accordingly. The study will be carried out by means of numerical modelling (Delft3D and/or OpenFOAM, depending on the scale of the problem) and by analyzing existing ADCP and CTD measurements, which have been carried out by Rijkswaterstaat and the University of Twente. This project will be part of the SALTISolutions programme, which includes many partners from academia, knowledge institutions, consultancy, and governmental organizations.

The EngD researcher will be based at the Marine and Fluvial Systems (MFS) group at the Department of Civil Engineering of the Faculty of Engineering Technology of the University of Twente (UT).

• MSc in Civil/Hydraulic Engineering, Geosciences or related discipline.
• You have sound programming skills (e.g Python, Matlab).
• You have experience with data analysis and hydraulic modelling.
• Your organizational skills are good.
• You are enthusiastic, independent and have a problem solving attitude leading to a design
• You are willing to contribute to the Civil Engineering teaching program and to supervise MSc thesis projects.
• You are fluent in English, both spoken and written (IELTS ? 6.5 or equivalent).

Candidates who do not possess all these skills but are willing to develop them along the EngD trajectory, are also encouraged to apply. Some of the desired skills can be acquired during an individual training program of 1500 hours that is part of the PhD project.

• Challenging work in an inspiring multidisciplinary environment with enthusiastic colleagues.
• Two-year fulltime EngD position, with a qualifier exam after 6-9 months
• Full status as an employee at the UT, including pension and health care benefits
• Tailor-made educational/development program of at least 10 months (53 EC), including visits to conferences.
• A salary of €2.618,- gross per month.
• An annual holiday allowance of 8% of the gross annual salary, and an annual year-end bonus of 8.3%.
• Minimum of 29 holidays per year in case of fulltime employment.
• You have to be willing to move to (the vicinity of) Enschede. A relocation allowance or temporary housing allowance may be part of the offer.
• The University of Twente is situated on a green and lively campus with lots of facilities for sports and other activities.
• We provide excellent mentorship and a stimulating research environment to accelerate your further professional and personal growth.

Your first responsibility is to do the research and get education, but you may also will acquire teaching experience (about 5% of your time). We support you to broaden your knowledge by joining international exchange programs, by participating in national and international conferences and workshops and by visiting industrial companies, research institutes, and universities worldwide.