This site is using cookies to collect anonymous visitor statistics and enhance the user experience. OK | Find out more

A strategic programme for NERC Lowland catchment research
Skip to content

Towards a methodology for determining the pattern and magnitude of recharge through drift deposits: Summary

A fuller description of this project is also available.

Overview of project & aims

This project's goal has been to improve the current understanding of the relationship between glacial drift structure and recharge, for groundwater sustainability and vulnerability assessments. Researchers gatherd data to describe the physical and hydraulic conditions at different scales of measurement. Identifying and comparing alternative strategies to aquire data was as important as gathering data itself. This project improved the description of the processes governing recharge and enhanced our understanding of the pathways and rates of migration through the shallow subsurface.

Aims

The primary objective was to gain greater insight into the hydraulic properties and processes of the main glacial formations overlying the Permo-Triassic sandstone aquifer that control the patterns and magnitudes of recharge to the underlying aquifer. A related and key objective was to seek a general method for estimating recharge patterns through drift based on the identification of an appropriate strategy for the collection of field measurements at the catchment scale.

Main findings

The lodgement till hydraulic properties are significantly controlled by vertical desiccation cracks that allow significant rapid vertical flow through the otherwise low permeability tills.

The spacing and depth of the desiccation cracks are highly organised, indicating that they were generated concurrently. They are essentially uniform over the region, therefore estimates of recharge do not require extensive mapping of these features.

While the till hydraulic properties would suggest that there is little recharge taking place through the tills, lateral flows above the tills to the till edge and subsequent recharge by deep infiltration along the till edge provides significant enhancement of the overall recharge from the tills.  More about the main findings of this project

Project outputs

  • Improved glacial drift mapping and characterisation of the glacial drift for recharge estimation, using a combination of low density surface geophysics and targeted sampling methods.
  • Completion of a 3D conceptual hydrogeological model of the glacial deposits spanning all field scales from local to catchment. The model is quantified using geostatistical simulations approaches to investigate both the magnitude and timing of recharge and the uncertainty in its estimation.  More about the outputs of this project

Description of activities

The study was undertaken within a sub-catchment of the Tern River basin in Shropshire, UK. Researchers used both invasive and non-invasive methods of collecting data spanning a range of scales from centimetres to kilometres. The data collected incorporated high resolution time dependent measurements. New insights were developed that quantify important components of the complex structures within the different deposits (lodgement tills, glacial outwash and weathered sandstones) and the ground surface.

At the smallest scale, two instrumented sites in the Tern catchment were constructed to undertake the primary process-based experimental programme. At the larger scales, surface geophysical methods were employed to acquire the necessary field to regional scale spatial data. Additionally, invasive sampling using direct drilling of the top 10 metres of the formations was undertaken to verify the interpretations of the geophysics. Finally, a detailed 3 dimensional model of the major drift formations was undertaken to explore the extent to which the shallow glacial deposits can be mapped.

Areas of application

The primary application areas for the research are climate change prediction, contaminated land and pollutant risk assessment, and performance assessment for the geological disposal of nuclear waste. Those organisations with requirements for the knowledge gained from this study will be primarily involved in environmental decision making and risk assessment.  More appliations of this project

Researchers' details

Principal Investigator:

Co-investigators:

More researchers who worked on this project More researchers who worked on this project

Publications

All publications from this and other LOCAR projects are listed in the publications database.

Selected publications from this project are listed below. The full list of publications and recommended reading can be viewed in the project description Full publication list for this project

Selected publications

Mackay R, Cuthbert M O, Ash H & Tellam J H, 2005. Towards an up-scaled model of aquifer recharge through glacial drift deposits, Shropshire, UK. Model Care 2005 Conference Proceedings, The Hague, The Netherlands.

Mackay R, Cuthbert M O, Ash H & Tellam J H, 2006. Numerical upscaling to quantify aquifer recharge through glacial drift deposits, Shropshire, UK. In Bierkens, M. F. P., Gejrels, J. C., and KOvar, K. (eds) Calibration and reliability in groundwater modelling: from uncertainty to decision making, IAHS Publication 304, 52-57.

Cuthbert M O, Mackay R, & Tellam J H, submitted 2008. The use of electrical resistivity tomography in deriving local scale models of recharge through superficial deposits, Quarterly Journal of Engineering Geology and Hydrogeology.

Full list of publications resulting from this project Full publication list for this project

Back to top Back to top of page