Eddleston experimental site model information

Eddleston experimental site.

Built by BGS in GSI3D V3 and Gocad and subsequently converted to 3D pdf, this model covers about 0.23 km2 of the floodplain and valley side of the catchment of the Eddleston Water, west of the A703, north of Peebles in the Southern Uplands of Scotland. The model is depicted with ×2 vertical exaggeration. It forms part of the wider Eddleston Water Project, which is coordinated by the Tweed Forum, and aims to reduce the impact of flooding in and downstream of Eddleston village by natural flood management.

The model is calculated from a digital elevation model (DEM) high resolution (2 m) LiDar data. It is based upon primary 1:500 scale geological mapping, a bespoke grid of soil auger holes, trial pits and boreholes, as well as the results from three types of shallow geophyscial survey: electromagnetic induction (EM, also referred to as ground conductivity mapping); 2D electrical resistivity tomography (ERT), and ground penetrating radar (GPR).

The modelled area covers a pastoral landscape that is typical of some flood prone valleys of the Scottish Borders, where the surface drainage has been modified by the straightening of river channels and construction of embankments.

Downloading the model

You will first need Adobe Acrobat Reader. If you have problems, update to the latest version of this program from the Adobe website. Once the model is opened, enable JavaScript in order to view its full functionality, notably the ability to explode the multiple modelled surfaces.

Superficial geology

The model straddles the alluvium of the Eddleston Water and the western flank of its valley immediately upstream of Eddleston village. The valley side is mantled by thin, discontinuous spreads of till and head (slope deposits such as gelifluctates and solifluctates, and recently eroded soil material, called colluvium).

The floodplain is underlain by a valley fill sequence, which reaches to around 20 to 30 m depth. The Holocene alluvial sediments extend to approximately 6 m depth as a relatively continuous layer. They principally comprise sandy gravel, locally overlain and interbedded with silt and fine sand and peat. Below this, from approximately 7 m to between 12 and 15 m depth, is a layer of glaciofluvial gravel. This gravel, which thickens towards the centre of the floodplain, overlies glaciolacustrine silts and clays that are thought to be more than 15 m in thickness along the central axis of the valley.

Bedrock geology

Weakly metamorphosed Ordovician wacke sandstones and siltstones of the Portpatrick Formation of the Scaur Group underlie the whole area of the model; they are locally exposed on the western side of the valley.

References

Archer, N A L, Bonell, M, Coles, N, MacDonald, A M, Auton, C A, and Stevenson, R.  2013.  Soil characteristics and landcover relationships on soil hydraulic conductivity at a hillslope scale: a view towards local flood management.  Journal of Hydrology, 497, 208–222.

Callaghan, E A.  2013.  Metadata report for the Eddleston Water Floodplain GSI3D model.  British Geological Survey Internal Report, IR/13/032, 17pp.

Ó Dochartaigh, B É, MacDonald, A M, Merritt, J E, Auton, C A, Archer, N, Bonell, M, Kuras, O, Raines, M G, Bonsor, H and Dobbs, M.  2011.  Eddleston Water Floodplain Project: Data Report.  British Geological Survey Open Report, OR/12/059. 95pp.

Contact

Please contact Clive Auton for further information.