The low-lying southern coastal hinterland of the Moray Firth is one of the most populous parts of the Highlands. It is blessed with fertile soils, principally derived from sandy glacial sediments laid down by glaciers that flowed from the Great Glen and surrounding uplands. Interaction between these glaciers has left behind a complex and often thick sequence of highly permeable sediments, which obscure much of the underlying Devonian sandstone bedrock between Elgin and Inverness.
We collect digital geological and hydrogeological data from this area to produce linked 3D shallow groundwater models. This helps us to understand the influence of geological deposits on groundwater flow, the hydrology of flood-prone rivers, and the dynamics of past ice-streams. This type of information was used in the construction of the Forres area flood defence scheme.
Since 2007, the BGS has been developing 3D models to capture and visualise the complexity of both the superficial and bedrock geology. These models will enable planning authorities and regulators to address the land use issues associated with rapidly increasing urban development, particularly around Inverness.
One of the most significant issues is the potential for river flooding. This prompted the construction of the first bespoke linked field survey and 3D geological framework model in Scotland, for the ground around the town of Forres. Targeted field investigations by a team of geologists, hydrogeologists and engineering geologists enabled a complex 3D geological model to be produced.
This work has been used to investigate the shallow groundwater component of flooding within the Lower Findhorn catchment. The collaborative research, which allowed grouping of the superficial deposits in terms of their volume and permeability, enabled construction of a detailed shallow groundwater model. This built upon the results of commissioned site investigations, as well as an evaluation of new and pre-existing surface and subsurface data.
The results of these studies have influenced the planning and design of flood alleviation measures within the flood-prone ground.
Since 2011, many of the modelling concepts developed for the Forres modelling studies have started to be applied to Inverness. Here, the complex geology is rapidly being concealed by man-made deposits and modified by excavations associated with the expanding city.
The results of co-funded geophysical surveys, undertaken by BGS marine geologists in the adjacent shallow waters of the Firth, are now being included in the developing model for Inverness and its suburbs. This will provide a holistic 3D baseline for the future development of the whole onshore-offshore area.