‘Karst’ is a geomorphological term applied to the landscape that results from the dissolution of soluble rocks, such as the characteristic limestone pavements of the Pennines. Research at the BGS extends beyond the distribution and processes associated with sinkhole formation to the broader subject of karst in general.
We maintain a number of databases that relate to karst, including a database of sinkholes and the National Karst Database. The National Karst Database has recorded over 10 000 sinkholes on the completed desk study research areas.
Understanding the nature and distribution of karst is important both for engineering geology and hydrogeological applications, as well as understanding landscape evolution. Specific challenges for engineering geology include:
- characterising the variation in depth to rockhead resulting from variable rates of dissolutional lowering of rockhead
- determining the extent of subsurface voids
- determining the position of the groundwater table
Usually, the hazards associated with karst can be mitigated by through planning, good site investigation (with geophysics and boreholes), appropriate design and proper maintenance of infrastructure such as drains and services. Care is required when installing any structures that could affect the local groundwater flow or groundwater levels, including soakaways (sustainable drainage systems or SuDs) and open-loop ground-source heat pumps. these may be impractical on soluble rocks in some places.
Reflecting this, there is a strong collaborative approach to BGS research. Karst research draws public science funding, grant funding and commercial income to investigate a range of research activities including:
- karst susceptibility
- domain-based karst characterisation and responsive visits to provide information for a range of stakeholders (including for emergency response)
- chalk karst and its influence on groundwater resources
- engineering geology associated with salt karst
- the extent and distribution of gypsum karst, e.g. Ripon, UK
- the influence of karst on groundwater and engineering in a range of limestone formations
- landscape evolution and the dating of speleothems
- weakly karstic aquifers.
- cave research and conservation
- Ensure that areas and a safety perimeter are cordoned off and keep people away.
- Notify the landowner and/or emergency services as appropriate.
- If services pipes (e.g. gas or water) are left suspended, ensure that infrastructure managers are contacted, e.g. Safety and emergencies (National Grid) and Emergencies (United Utilities).
- Ensure that any triggering processes (e.g. leaking drains) are managed to minimise the potential for ongoing subsidence.
- Contact your local council/building control to notify them; find out if there is a history of such features in the area and request a list of consulting engineers that are able to give appropriate advice on the correct procedures for stabilising them.
- The BGS can be approached for more information on sinkholes or read our specific homeowner advice. We may also be interested in recording the event in our sinkhole database.
If the concern is about whether a sinkhole is developing on a specific property, monitor any suspect depressions, check that there are no obvious potential triggering mechanisms, e.g. leaking pipes, check for any associated cracks in adjacent buildings and seek guidance from your council/building control.