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January 16, 2017

Revealing hydrological and biogeochemical heterogeneity at the groundwater-surface water interface using geophysics

Revealing hydrological and biogeochemical heterogeneity at the groundwater-surface water interface using geophysics 400 x 400 px

It is now widely recognised that hydrological and biogeochemical processes that occur at the interface of groundwater (GW) and surface water (SW) can have a significant impact on catchment water quality and ecosystem health. Significant heterogeneity in the fabric of the subsurface at the GW-SW interface can lead to complex fluid flow pathways, both of which can exert a strong control on biogeochemical cycling.

Revealing such heterogeneity remains a challenge because of the limitations of traditional field experimental processes. In this project we explore the use, and provide additional development, of geophysical methods tailored for characterising the GW-SW interface. Our vision is a suite of tools that can ultimately be utilised along an entire reach of a river, i.e. to investigate an entire catchment.

The project will be primarily field-based, focussing on sites where the supervisory team have already conducted preliminary, related, work. The sites to be utilised are: the Lambourn Observatory in Berkshire (Chambers et al., 2014, WRR, doi: 10.1002/2014WR015643) and the River Leith in Cumbria (Binley et al., 2013, WRR, doi:10.1002/wrcr.20214).

We will explore a range of field-based techniques including: (1) new multi-coil EM conductivity measurement technology; (2) electrical resistivity tomography and induced polarisation, exploiting in-stream semi-permanent electrode arrays; (3) electrical imaging of injected tracers to reveal fluid flow pathways. A laboratory-based study of river bed sediment samples will explore links between geophysical, hydraulic and geochemical properties.

The student will be given training on the use of geophysical methods, processing and modelling of geophysical data, field and laboratory investigative techniques. The student will also be given the opportunity to spend time at the British Geological Survey, and access to BGS geophysical laboratories and field equipment. The student will gain experimental and modelling skills, along with insight into scale-dependent processes, all of which will be valuable for career progression.

The PhD will be hosted by the University of Lancaster with the British Geological Survey as a CASE partner. The student will be jointly supervised by Professor Andrew Binley (Lancaster) and Dr Jonathan Chambers (BGS), and will have the opportunity and support to spend time working at both institutions.

Eligibility: Applicants should hold a minimum of a UK Honours Degree at 2:1 level or equivalent in subjects such as Environmental Science, Earth Science, Physics, Engineering, Natural Sciences. No prior experience of applied geophysics is necessary but it will be advantageous.

For further details please contact Professor Andrew Binley, a.binley@lancaster.ac.uk or Dr Jonathan Chambers, jecha@bgs.ac.uk