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A strategic programme for NERC Lowland catchment research
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Hydrogeophysical characterisation of the riparian zone in Chalk catchments

Title

Investigating stream groundwater interactions in lowland Chalk catchments using hydro-geophysical characterisation of the riparian zone.

Overview of project

This project studied groundwater-surface water interaction in the Pang and Lambourn catchments using a series of catchment- and reach-scale measurements of stream flow, stream and groundwater chemistry. These were combined with detailed geophysical surveys at specific sites. Additional work was also conducted along a reach of the River Tern at one of the LOCAR infrastructure sites.

Previous studies have suggested that the assumption of uniformly increasing flow accretion in Chalk catchments is untrue. This study has provided a finer spatial and temporal resolution of stream flow monitoring and water chemistry analysis in order to improve the description of surface-groundwater interaction and flow accretion within these catchments.

Aims

This study aimed to enhance the knowledge of the cause and nature of hydraulic interaction between stream and aquifer in the riparian zone of the study catchments. A major objective was the development of a practical methodology for wide-scale application in water resource management in lowland catchments.

Main findings

Through fine spatial and temporal resolution of stream flow monitoring and water chemistry analysis we have demonstrated a range of controls on groundwater-surface water interaction in Chalk catchments. For example, landscape features such as dry valleys are significant in the middle and upper Lambourn and regional groundwater flow and structural discontinuities within the substrata, such as karstic or solutions features, are important in the lower Pang. Water inflows into the Lambourn associated with dry valley features are more extensive than previously assumed and flow accretion along reaches adjacent to these features is maintained under seasonally varying conditions, relative to the total contribution along the entire length of the river. Accretion associated with karstic Chalk shows little seasonal variation, it appears to be able to sustain significant flow even under net low flow conditions.

Hydrogeophysical surveys were valuable for improved hydrostratigraphic mapping within the riparian zone and for measurement of changes in pore-fluid chemistry in near-surface sediments.

The work has allowed the development and application of natural tracers to identify and characterise groundwater-surface water interaction. An intensive survey of carbon dioxide and radon within river and borehole waters has demonstrated the value of such tracers for qualitative assessment of streamflow generation. But it has also revealed that quantitative use of such tracer data may be limited due to the heterogeneity and temporal dynamics of source terms.

A reach-scale investigation of the River Tern has identified significant variability in river bed seepage and potential residence times of groundwater contaminants. This has led to the development of a new technique which uses temperature time series from river bed piezometers to compute influx estimates. The approach uses daily variation of temperature in river water and the river bed to determine the velocity of water entering or leaving the river.

The project has provided a wealth of new data on river flow, streamwater chemistry and borehole water chemistry which will supplement other studies within the area. Flow data were provided to assist many other LOCAR projects. In addition, the project provided the Environment Agency with new flow data, to assist with river abstraction licences to estimate contaminant travel times.

Description of activities

  • Measurements of river flow, streamwater chemistry and borehole water chemistry
  • Stream flow monitoring and water chemistry analysis
  • Hydrogeophysical surveys
  • Development and application of natural tracers (e.g. carbon dioxide and radon) to identify and characterise groundwater-surface water interaction.

Areas of application

The Environment Agency are utilising the results of the project in a range of areas, for example, to improve rating curves for weirs within the catchments studied and to assist with river abstraction licences.

The data from the Tern field site has provided a significant input into the Environment Agency's Hyporheic Zone Research Programme

Related and future work

The Environment Agency funded an extension of the research into the Tern catchment.

Researchers' details

Principal Investigator:

Co-investigator:

Other researchers:

  • Dr N Crook, Lancaster University
  • Dr J Griffiths, Centre for Ecology and Hydrology
  • J Nutter, Centre for Ecology and Hydrology

Publications

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

Refereed journal papers

Griffiths, J., Binley, A., Crook, N., Nutter, J., Young, A. and Fletcher, S. 2006. Streamflow generation in the Pang and Lambourn catchments, Berkshire, UK, Journal of Hydrology (in press).

Griffiths, J., Nutter, J., Binley, A., Crook, N., Young, A. and Pates, J. 2006. Variability of dissolved CO2 in the Pang and Lambourn Chalk Rivers.(submitted to Hydrology and Earth Systems Science).

Jarvie, H.P, C. Neal, M. D. Jürgens, E. J. Sutton, M. Neal, H. D. Wickham, L. K. Hill, S. A. Harman, J. J. L. Davies, A. Warwick, C. Barrett, J. Griffiths, A. Binley, N. Swannack and N. McIntyre, 2006, Within-river nutrient processing in the Pang and Lambourn Chalk streams, UK. Journal of Hydrology (in press).

Keery, J., A.Binley, N.Crook and J.W.N. Smith, Temporal and spatial variability of groundwater-surface water fluxes in a lowland river: The use of temperature time series. (submitted to Journal of Hydrology).

Mullinger, N.J., A.Binley, J.M. Pates and N. Crook, 2006, Spatial and temporal variation of groundwater sources in the Pang and Lambourn catchments, UK. (submitted to Journal of Hydrology).

Wheater, H.S., D. Peach and A. Binley, 2006, Characterising Groundwater-dominated Lowland Catchments - the UK Lowland Catchment Research Programme (LOCAR), Hydrology and Earth Systems Science (in press).

Conference publications

Crook, N., A. Binley, J. Griffiths, J. Pates, and A. Young, 2004, Identification and quantification of river-groundwater interaction in the lowland Chalk catchments of the Pang and Lambourn. BHS International Conference Hydrology: Science & Practice for the 21st Century, July 2004. Paper presentation and peer reviewed publication in conference proceedings.

Crook, N., H. Musgrave and A.Binley, 2006, Geophysical characterisation of the riparian zone in groundwater fed catchments, In: Proc. Symposium on the Application of Geophysics to Engineering and Environmental Problems, Seattle, USA, April, 2006.

Keery, J., A. Binley and J. Smith, 2005, Quantification of groundwater-surface water fluxes using temperature time series. Oral presentation H13K-05 at the American Geophysical Union Fall Meeting, December 2006, San Francisco, USA.

Wheater, H.S., D. Peach and A. Binley, 2005, Characterising Groundwater-dominated Lowland Catchments - the UK Lowland Catchment Research Programme (LOCAR), Oral presentation H23G-04 at the American Geophysical Union Fall Meeting, December 2006, San Francisco, USA.

Recommended reading

Vereecken, H., Binley, A., G. Cassiani, A. Revil and K. Titov, 2006, Applied Hydrogeophysics, Springer, 383pp.

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