Article Figures & Data
Figures
- Fig. 1.
Methods of temperature measurements in coalfields; 1–2, geophysical downhole logging of water-filled boreholes and shafts; 3, in situ coal seam measurements in operational ‘dry’ mines. Diagram is not to scale and is for illustrative purpose only. Amended by Craig Woodward, BGS after Ben Gilliand © BGS, UKRI.
- Fig. 2.
Location of coalfield ‘Mine Water Blocks’ and data points used in this study. Contains Ordnance Survey data © Crown Copyright and database rights 2020. Contains Mine Water Blocks © Copyright Coal Authority (2020) all rights reserved and BGS, UKGC locations © BGS, UKRI.
- Fig. 3.
Box plot of BGS UKGC (blue) and historical in situ coal strata temperature (grey) from coalfields in equilibrium (does not include pumped data). BGS UKGC (blue) borehole temperature data from the BGS UKGC from all coalfields plus a 500 m radius. Data © BGS, UKRI. ‘STRATA’ are historical in situ strata temperatures (grey) from operational British coalfields (1866–1924). In box plot, box is upper and lower quartile; whiskers are maximum and minimum, red line is mean, black line is median, outlier dots are 95th and 5th percentiles. Data from Everett (1870a, b, 1871, 1872, 1873, 1877, 1879, 1880, 1881, 1882a), HMSO (1871), Prestwich (1887), Anon. (1919–20), Davies (1919–20), Rees (1920–21), Graham (1921–22) and Jones (1924, 1926).
- Fig. 4.
(a) Down-shaft temperature profiles measured at ‘Dawdon Theresa Shaft’ North East England where pumping (P) started in 2010 at 100 l s−1; (b) Down-shaft temperature profiles measured at ‘Horden South Shaft’ where pumping (P) started in 2004 at 40 l s−1, was increased to c. 120 l s−1 in 2008, and after 2008 returned to c. 40 l s−1. At both sites the pump inlet depth was c. 100 mbgl. Black arrows indicate general trends of increasing temperature. Data copyright Coal Authority (2020) all rights reserved.
- Fig. 5.
Average (arithmetic mean) equilibrium and pumped temperatures at 100 mbgl. Dots indicate where MWB temperature has been estimated by applying average values from adjoining Mine Water Blocks within the same coalfield. Contains 1:50 000 BGS DiGMap ©BGS, UKRI and Ordnance Survey data © Crown Copyright and database rights 2020. Contains Mine Water Blocks and data © Copyright Coal Authority (2020) all rights reserved.
- Fig. 6.
Average (arithmetic mean) equilibrium and pumped temperatures at 200 mbgl. Dots indicate where MWB temperature has been estimated by applying average values from adjoining Mine Water Blocks in the same coalfield. Contains 1:50 000 BGS DiGMap ©BGS, UKRI and Ordnance Survey data © Crown Copyright and database rights 2020. Contains Mine Water Blocks and data © Copyright Coal Authority (2020) all rights reserved.
- Fig. 7.
Average (arithmetic mean) estimated temperature in Mine Water Blocks in equilibrium from 300 to 600 mbgl. Dots indicate where MWB temperature has been estimated by applying average values from adjoining Mine Water Blocks in the same coalfield. Contains 1:50 000 BGS DiGMap ©BGS, UKRI and Ordnance Survey data © Crown Copyright and database rights 2020. Contains Mine Water Blocks and data © Copyright Coal Authority (2020) all rights reserved.
- Fig. 8.
Average (arithmetic mean) estimated temperature in undisturbed Mine Water Blocks in equilibrium from 700 to 1000 mbgl. Dots indicate where MWB temperature has been estimated by applying average values from adjoining Mine Water Blocks in the same coalfield. Contains 1:50 000 BGS DiGMap ©BGS, UKRI and Ordnance Survey data © Crown Copyright and database rights 2020. Contains Mine Water Blocks and data © Copyright Coal Authority (2020) all rights reserved.
Tables
Attribute field Example Mine Water Block name Nottingham South Coalfield Nottinghamshire Measured temperature data Yes Minimum depth of recorded workings (mbgl) 0 Maximum depth of recording workings (mbgl) 746 100 m depth* Average (mean) temperature (°C) 11.9 Maximum temperature (°C) 12.3 Minimum temperature (°C) 11.6 * Average, maximum and minimum values are entered every 100 m until the maximum depth of recorded working (rounded to the nearest 100 mbgl).
- Table 2.
Summary of coal mine temperatures from Mine Water Blocks at 100 m depth intervals across the British coalfields
Depth (mbgl) n Minimum T (°C) Maximum T (°C) Range T (°C) Mean T (°C) Median T (°C) Mean geothermal gradient (°C km−1)* 100 76 9.5 15.6 6.1 11.7 11.6 26.6 100 20 9.2 19.8 10.6 13.3 13.3 200 76 10.7 17.8 7.0 14.2 14.3 25.9 200 16 11.8 21.5 9.7 15.1 15.1 300 69 12.9 23.7 10.8 16.7 17.0 25.6 300 10 13.4 23.0 9.6 16.6 16.6 400 70 14.2 25.6 11.4 19.2 19.4 25.4 400 7 13.7 21.8 8.1 16.8 16.8 500 66 15.5 29.6 14.1 21.8 22.3 25.5 500 5 14.1 23.3 9.2 17.7 17.7 600 53 16.8 33.6 16.8 23.7 24.4 24.5 700 51 18.1 37.6 19.5 26.2 27.0 24.6 800 44 19.5 41.6 22.2 28.2 27.9 24.0 900 34 20.8 45.6 24.9 30.8 30.1 24.2 1000 27 22.1 49.6 27.5 33.4 35.8 24.4 1100 9 23.4 52.8 29.4 37.4 34.6 25.8 1200 2 32.8 40.9 8.1 36.9 36.9 23.2 Equilibrium temperatures are in in normal font; data from pumped mine water bodies are in italics. Data compiled from a combination of downhole temperature profiles, bottom hole temperatures and historical strata temperatures. Data © Copyright the Coal Authority all rights reserved; © British Geological Survey, UKRI. Geothermal gradients not calculated for disturbed data.
n, number of Mine Water Blocks with measured data; it should be noted that some MWB can have both equilibrium and pumped data.
*Calculated using 9 °C as average UK surface temperature and mean temperature.
- Table 3.
Britain's coalfields ranked by order of their average geothermal gradient at 100 m depth intervals (does not include pumped data)
Mean air T (°C) 1980–2019 MWB total MWB with data Depth below ground level (m) Mean geothermal gradient (°C km) 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 North East 9.0 29 9 31.9 32.1 35.7 35.7 36.1 34.3 Cumbria 9.0 9 3 32.7 32.5 32.4 32.4 32.4 32.5 Yorkshire 9.0 10 5 32.9 31.9 31.3 30.6 31.7 31.6 32.4 32.4 32.3 32.1 36.4 32.3 Central Scotland 8.1 2 2 35.0 30.0 28.0 28.2 27.9 27.6 29.1 29.0 29.0 29.6 34.5 29.8 Nottinghamshire 9.6 18 10 24.8 27.7 28.5 28.9 29.1 29.3 29.4 29.2 29.2 28.5 Ayrshire 7.4 5 1 27.0 26.5 26.8 Kent 10.4 4 3 25.2 25.4 25.6 24.6 26.4 26.4 26.5 26.5 25.8 Lothian 7.4 1 1 40.0 25.0 24.0 22.9 22.3 21.9 21.7 21.4 21.3 21.1 24.2 Lancashire 9.0 18 7 30.1 26.7 25.6 25.0 24.7 23.8 23.6 23.5 21.8 22.9 21.6 23.2 19.8 24.0 Bristol and Somerset 9.9 8 3 20.7 23.5 24.4 25.0 25.2 25.5 25.6 22.9 23.0 24.0 South Derbyshire 9.6 2 2 23.0 24.3 23.6 Staffordshire 9.6 11 8 17.1 19.3 20.1 21.6 22.8 23.0 23.1 23.1 23.2 23.3 30.5 22.5 Douglas 8.1 1 1 23.0 22.5 22.3 22.2 22.1 22.0 22.0 22.0 21.9 21.9 22.2 Fife 7.4 3 3 28.3 24.2 23.1 21.1 20.5 20.2 19.9 19.8 19.6 21.8 21.9 South Wales 9.9 22 17 13.5 17.6 19.0 19.3 20.2 20.5 20.7 20.9 22.3 18.4 22.5 19.5 Warwickshire 9.6 15 2 16.5 17.0 17.3 17.4 17.5 17.5 17.5 17.5 17.4 17.3 Median geothermal gradient of British coalfields 24.1 The following coalfields are not included as they have ≤1 data point: North Wales, Leicestershire, Forest of Dean and Shropshire. Data compiled from a combination of downhole temperature profiles, bottom hole temperatures and historical strata temperatures. Data © Copyright the Coal Authority; © British Geological Survey, UKRI.
Current issue
