PhD 2: Imaging flow dynamics and resulting reactivity in the transition zone between streams and riparian aquifers

Objectives: Identify and characterize the space and time patterns of exchange between streams and their riparian zone and the resulting potential for solute turnover by jointly using novel and advanced tracing, imaging, and modelling techniques

Expected Results: This ESR project aims at understanding the links between physical controls (e.g. stream stage, subsurface hydraulic conductivity and heterogeneity) and biogeochemical process patterns (space and time patterns of reactivity) in riparian aquifers. At the River Selke TERENO field site, the natural EC contrasts between stream water and groundwater can be used to trace stream water intrusion into the riparian aquifer. Temporal dynamics of stream-groundwater exchange will be derived by analysis of time series of conservative solutes like EC measured in the stream and piezometers in the riparian aquifer. In close conjunction, spatial infiltration into the riparian aquifer will be imaged using ERT surveys that are optimized for the detection of natural EC contrasts. Using the identified patterns of water and solute fluxes and additional measurements of O2, NO3 in the stream and piezometers with varying distance to the stream will enable a mapping of the turnover capacity for reactive solutes in the riparian aquifer. A synthesis of the observations will be achieved using a reactive transport model to replicate flow and reactivity patterns. The systematic joint evaluation of temporal dynamics and spatial patterns of flow and reactivity with state of the art imaging and sensing methods and models is a novel approach to investigate reactive potential of riparian aquifers. Collaborations on geophysical and thermal imaging techniques are planned with ESRs 6, 7, 12, 13.

Supervisors: UFZ Leipzig / Co-Supervisors: UCPH Copenhagen, UNINE Neuchâtel
Contact : Jan Fleckenstein jan.fleckenstein(at)ufz.de

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