1 PhD position in "Rapid regional mapping of fresh-saline groundwater distributions and hydrogeological properties using airborne geophysics" in Netherlands | Utrecht University

The occurrence and dynamics of saline groundwater are both important phenomena for the use of freshwater resources in the subsurface. Accurate maps of the fresh-saline distribution on regional scale, as well as thorough understanding of the (potential) salt transport with groundwater are prerequisite for sustainable groundwater management. This asks for proper knowledge of the fresh-saline distribution and the hydraulic properties of the subsoil. Conventional salinity measurements (e.g. via observational well sampling or basic geophysical techniques) are time-consuming, expensive and have a limited spatial support. Recent developments in Airborne Electromagnetic Monitoring (AEM) are promising regarding mapping geological structures as well as salinity.

In principle, AEM is able to cover large regions in a short period of time. However, AEM needs in situ (earthbound) measurement for validation. Moreover, the 3D salinity image resulting from the geophysical observations should be confronted with (numerical) variable-density groundwater models in order to constrain the current distribution of saline groundwater by the physics of palaeo-groundwater flow.

The main goal of this PhD project is to develop and apply data-assimilation methods to optimally combine a variable-density groundwater flow and coupled salt transport model with airborne geophysical data and in-situ observations to jointly estimate the regional fresh-salt water distribution and hydrogeological properties. The results will be further used to map out the vulnerabilities and opportunities for fresh as well as brackish water use and control.

The work will be carried out in the framework of the STW Perspectives project WATER NEXUS in close cooperation with Deltares and TNO/Geological Survey of the Netherlands. In this framework, the PhD will closely work together with a second PhD responsible for setting up the groundwater flow and salt transport model, which is the basis for scenario simulations under future global change.

Requirements

Highly motivated candidates with an MSc degree in hydrology, hydrogeology, physical geography, civil engineering, engineering geology, applied mathematics or a related field are encouraged to apply. The candidate should have a proven knowledge of numerical modelling and/or data assimilation. Programming experience is a serious advantage. He/she should be proficient in English and have excellent scientific writing and presenting skills. The candidate is an enthusiastic team player and has good communicational skills. Candidates who do not speak or understand Dutch are expected to communicate in Dutch within two years.