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Investigation of flow heterogeneity in the Chalk: field studies and stochastic models: summary

A fuller description of this project is also available.

Aims

This project sought to provide an improved understanding of saturated flow through Chalk, the UK's primary aquifer. This is important for the further development of groundwater flow and transport modelling and for the interpretation of pumping and tracer test data, which are generally used to calibrate and/or condition such models.  More about the aims of this project

Main findings and outputs

Research achievements:

  • Characterisation of flow heterogeneity at the local scale: important progress has been made on how various types of data can be integrated in order to quantify borehole/aquifer interaction under ambient and pumped conditions.
  • Prediction of flow heterogeneity using fracture flow modelling: the work has made a major contribution in demonstrating that the observation of a fracture (either visually or from caliper logs) does not necessarily indicate permeability or, more importantly, flow. It has also shown that flow horizons may change markedly under ambient conditions and when groundwater is being pumped.
  • Up-scaling of hydraulic parameters: the research has also pointed to the challenges faced in applying local data (where an artificial perturbation has been imposed on the system) to regional models.  More about the main findings of this project

New modelling tools:

Description of activities

Fieldwork was undertaken at the Trumpletts Farm LOCAR site in the Pang catchment where three 100 m deep boreholes are located less than 150 m apart.

A range of field investigation techniques were employed to investigate local scale flow heterogeneity:

  • Standard suite of geophysical methods (caliper, temperature, conductivity, pulsed heat flow, etc.).
  • Video fracture logging.
  • Pumping tests under different water table conditions.
  • Double packer permeability tests.
  • Single borehole dilution tests.
  • Radially convergent tracer tests.

The collected data were analysed using both existing tools and those developed by the project, eg a purpose-built software tool for fracture analysis of borehole images.

New modelling techniques were developed to improve interpretation of single borehole dilution tests, radial flow tracer tests and pumping tests.

Areas of application

This work has important implications for the calibration of regional and local groundwater models. These are used in water resources planning which is directly linked to the Habitats Directive and the Water Framework Directive.

Related and future work

Work on a new pumping test solution incorporating the effects of turbulent flow is ongoing.

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 full description page for this project Full publication list for this project

Selected publications

Mathias, S.A., Butler, A.P. and Williams, A.T. 2007. Recovering tracer test input functions from fluid electrical conductivity logging in fractured porous rocks. Water Resources Research, 43(7), W07443, doi:10.1029/2006WR005455.

Mathias, S.A., Butler, A.P. 2007. Shape factors for constant-head double-packer permeameters. Water Resources Research, 43, W06430, doi:10.1029/2006WR005279.

Williams, A.T., Bloomfield, J., Griffiths, K. and Butler, A.P. 2006. Characterising the vertical variations in hydraulic conductivity within the Chalk aquifer, Journal of Hydrology, 330, 53-62.

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

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