The Talla Earth Observatory Project

Time-series monitoring for river flood alleviation in the Tweed Catchment

The Talla Earth Observatory in southern Scotland lies within a small catchment typical of the uplands of northern Britain. Four years of investigation have produced a highly detailed 3D model of the very shallow subsurface (uppermost 4 m). It has combined investigation of soils, their parent materials and deeper geology, to produce a holistic baseline against which time-series measurements of past and future landscape changes are being studied. Time-series of weather data and of shallow groundwater levels in boreholes are being integrated to assess the time lags associated with shallow groundwater storage and baseflow to the Talla Water (a headwater tributary of the flood-prone River Tweed).

Flooding in the upper reaches of the Tweed Valley, 20th August 2009

These time-series records are also being compared with lower resolution historical weather records and longer term proxy climate records from peat cores at Talla Moss (which span the last 4 500 years) to assess changes in precipitation levels and ground surface wetness through time.

Many of the integrated methods of ground investigation and monitoring developed at Talla are being applied to investigate the shallow groundwater component of river flooding at Eddleston, north of Peebles. This is a major study, combining river hydrology, shallow hydrogeology and the investigation of natural flood alleviation measures. It is being led by Dundee University in collaboration with BGS and is commissioned by the Tweed Forum.