Multibeam map of Windermere, Lake District, England

Multibeam map, North Basin

A new multibeam bathymetric survey was undertaken in Windermere in September 2010; further fieldwork was carried out in June 2011 and April 2012, including the collection of sediment samples from the lake bed and underwater video. These surveys were reported in 2012 — Windermere: lake environment and glacial history.

The results were used to identify five different sedimentary environments in Windermere, defined as: gyttja (organic rich mud), finely laminated mud, gravel, fine sand and bedrock.

The data from the surveys has been used to produce a landscape map of the lake — multibeam map of Windermere and other publications (see below).

Sediment coring

In April 2012, eight piston cores from the North and South Basin were collected using a floating platform designed by Uwitec. The longest core was 10 m in length and penetrated through the glacial clay into sand layers. This core is the longest core (to date) to have ever been taken from Windermere!

A) Uwitec floating platform on Windermere.
B) Sediment core on deck.
C) Section of a split core, showing laminated clay.

Core logging

The cores have been logged and analysed through a multi-sensor core logger, which measures the physical properties of core samples without destruction. This information will be correlated with existing geophysical data sets.

A number of the sediment cores have been run through the Itrax (multi-function X-ray core scanner) at the University of Southampton, and the geochemical properties of the cores have been analysed using the following techniques:

  • X-ray fluorescence (XRF) — used to determine element composition in sediments using the interaction of X-rays with a target material
  • lead-210 dating — used to determine how old a sediment is
  • caesium-137 — used to determine how old a sediment is
  • lead isotope determination — used to determine the source of lead

The results aim to examine the concentration of heavy metals in recent sediments, and assess the impact of mining, quarry development and anthropogenic activity on the lake-bed sediments. Initial findings suggest that while most element concentrations have been stable for the past 400 years, there was an increase in lead concentrations over the past 50 years and zinc concentrations over the last 25 years. Ongoing work aims to examine the source of these chemical fingerprints within the catchment. Contamination of heavy metals is possibly attributed to human and industrial activity within the catchment.

A number of short cores were also collected in areas where underwater video had identified a cover of filamentous growths forming mats across the lake bed. The water–sediment interface of these short cores has been analysed in detail using a range of methods (such as scanning electron microscopy; SEM). Conditions conductive to formation of growths possibly include increased sedimentation rates and nutrient enrichment, particularly through sewage discharge by nearby waste-water treatment plants

Fish spawning: Arctic charr

In addition to sediment coring, underwater video observations and sediment samples acquired in June 2011, April 2012 and May 2013 have been used to assess Arctic charr spawning grounds in Windermere. Arctic charr are recognised as a UK Biodiversity Action Plan (UK BAP) priority species. Windermere is the southernmost known spawning ground for the Arctic charr globally, and as such is an important indicator when considering the impact of environmental and climatic changes on habitats.

Our results indicate there has been a decline in Arctic charr spawning habitats over the past 50 years, particularly in the South Basin and an increase in finer sediment cover. Significant local pressures include eutrophication, lake warming, species introduction and anthropogenic activity (such as dredging).

Onshore mapping

Troutbeck alluvial fan delta, with corresponding aerial overlay, comprising merged LiDAR and multibeam datasets.

High resolution airborne LiDAR (Light detection and ranging) data from the Windermere catchment has also been analysed as part of this project. LiDAR data is an optical remote sensing technology that uses a laser to measure the distance between a sensor (normally airborne) and the ground surface, providing high resolution terrain data.

In particular, LiDAR data has been analysed in combination with multibeam bathymetry data and onshore geological and geomorphological field mapping to derive the glacial and post-glacial history of Troutbeck Valley (a sedimentologically important valley feeding into Windermere). Results from this research are published in the Proceedings of the Geologists Association (see below).

Recent publications

Miller, H, Cotterill, C J and Bradwell, T.  2013.  Glacial and paraglacial history of the Troutbeck Valley, Cumbria, UK: integrating airborne LiDAR, multibeam bathymetry, and geological field mapping.  Proceedings of the Geologists Association. (In Press).

Miller, H, Bull, J B, Cotterill, C J, Dix, J K, Winfield, I J, Kemp, A E S and Pearce, R B.  2013.  Lake bed geomorphology and sedimentary processing in glacial lake Windermere, UK. Journal of Maps 1–14.

Download a high resolution multibeam map of Windermere .

Acknowledgements

A large part of this project work is Helen Miller's PhD, which was funded by the BGS's BUFI, the University of Southampton and the Environment Agency. Additional project support was provided by the Centre for Ecology and Hydrology (CEH).

Contact

Contact Carol Cotterill further information