Geophysical Investigation of the Bosherston Lily Ponds, South Wales, UK

The Bosherston Lily pond is a man made water body situated in Pembroke, South Wales, UK. Created in stages between the late 18th and mid 19th century, the lily ponds were formed by damming a river valley. The ponds are now maintained by the National Trust and have been classified under the EC Habitat Directive as a Special Area of Conservation (SAC). The lily ponds are of great importance not only due to the diverse ecology but because of the significant financial income generated in the area by tourism. The lily ponds exist due to a delicate balance of influxes and outflows; any change could lead to the lily ponds demise. It has been noted that the summer level of the lake has decreased over the last 80 years. It is believed that the water is seeping away through cracks and crevices in the underlying carboniferous limestone. The aim of the geophysical survey was to locate possible conduits which would explain the decrease in water level. A combination of geophysical techniques were employed in order to comprehensively survey the subsurface; these included electrical resistivity arrays, ground penetrating radar and self potential surveys.