Eurizon.eu

Organization: Imperial College London

Location: London, UK

Field: geophysics

Requirements:

The project is ideal for a numerate geologist, geophysicist, physicist, engineer or mathematician who is interested in multidisciplinary research which combines the important aspects of geophysics and hydrology, and which will advance our understanding of a significant problem. It will provide an ideal route into either an industry or academic career.

Abstract:

The Chalk is the UK's principle aquifer, providing around 33% of public water supply in England and Wales. In south-east England, this proportion rises to over 70%. In coastal areas, intrusion of seawater into the Chalk poses a serious threat to groundwater quality. Coning of the saline water towards an abstraction well occurs if the well is pumped too hard.

Description:

The Chalk is the UK's principle aquifer, providing around 33% of public water supply in England and Wales. In south-east England, this proportion rises to over 70%. In coastal areas, intrusion of seawater into the Chalk poses a serious threat to groundwater quality. Coning of the saline water towards an abstraction well occurs if the well is pumped too hard. Because it is a local phenomenon, monitoring wells at a distance from the abstraction well may not intersect the cone, so its presence may not be detected until the salinity of the water produced from the abstraction well begins to increase.
Recent work at Imperial College suggests that measurements of spontaneous potential (SP) could be used to detect and monitor the movement of saline water towards an abstraction well in a freshwater aquifer. The SP acts to maintain overall electroneutrality when a separation of electrical charge occurs in response to gradients in pressure, chemical composition or temperature. If saltwater flows into the aquifer, gradients in chemical composition are present, leading to the generation of SP signals which are specifically associated with saltwater influx.
 
Project description
The aim of this multidisciplinary project is to determine whether measurements of SP, using both borehole and surface electrodes, can be used to detect and monitor the influx of saltwater into freshwater aquifers during abstraction, thus facilitating active management of abstraction to avoid saltwater reaching the wells and flowing to surface. The specific objectives are to

1. Measure the electrokinetic and electrochemical coupling coefficients for rock samples and water compositions obtained from coastal aquifers at risk of saltwater influx. Quantitative estimates of these coupling coefficients are required to model and interpret SP signals, but few measurements are available.
2. Use numerical modeling to predict the SP signals likely to be generated during abstraction at two coastal aquifer sites which are at risk of saltwater influx, to determine whether the saline front can be detected and monitored, and over what distances and at what spatial and temporal resolution.
3. Demonstrate the utility of the method at two well-characterized shallow aquifer test sites. A number of field experiments will be conducted, in which small volumes of saline water are injected and the resulting SP signals are measured.

The project is fully funded by NERC and Atkins and is jointly hosted by the Departments of Earth Science and Engineering, and Civil and Environmental Engineering at Imperial College. It also benefits from supervisory input from project partner Southern Water. The student will spend time working in the Atkins offices. The start date is 3rd October 2011.
 
How to apply
Applications should be made via Imperial College London's online system (details at www.imperial.ac.uk/earthscienceandengineering/courses/phdopportunities/phdapplicationprocedure). Informal enquiries can be addressed to Dr. Matthew Jackson at m.d.jackson@imperial.ac.uk or Dr. Adrian Butler at a.butler@imperial.ac.uk.

Deadline: 25-03-2011

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