OR/17/026 Appendix 5 - River basin management districts

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Mansour, M M, and Hughes, A G. 2017. Summary of results for national scale recharge modelling under conditions of predicted climate change. British Geological Survey Internal Report, OR/17/026.

A5.1 - General

Figure A18 to A39 display four plots for each of the eleven River Basin Management Districts (RBMD) covering England and Wales. The plots (clockwise from top left) are the average monthly recharge values for the historical simulation for each RBMD, average monthly change for each RBMD for the 2020s, average monthly change for the 2080s and average monthly change for the 2050s. There are different responses for each RBMD, but in general the 2020s are exhibit less variability than the 2050s and 2080s. Variability of the monthly change also exhibits an east-west split, with the western catchments demonstrating greater variability than the eastern ones. Finally the variability in the recharge season: September to April is generally greater than for the rest of the year (May to August).

To quantify the impact of climate change on total recharge and how this may change the total volume for 30 year periods both within the historical simulation and predicted future scenarios were calculated for each RBMD. Two 30 year periods (1961–90 and 1971–00) were chosen within the historical simulation. This enables any variability within these periods to be understood. These results were then compared to total recharge volumes for the 2020s, 2050s and 2080s for each RBMD. The results are summarised for each ensemble for each RBDM in Tables A1 to A11. and diagrammatically in Figures A18 to A39. To enable a comparison to be undertaken the minimum, maximum and average value is calculated for each time period.

The individual response for both recharge rates and volumes for each RBMD are detailed below.

A5.2 RBMD 2 - Solway Tweed

There is relative high recharge in the historical simulation (Figure A18). The comparison of ensembles for 2020s show a mixed response (some decreases and some increases over the year). For the 2050s there are increases earlier in the year, mixed in the summer, reduction in July, August, September, and increases in October November and December. The 2080s follow a similar pattern to the 2050s. The recharge totals increase from the historical simulation to the 2020s, reducing for the 2050s and increasing again in the 2080s (see Figure A19).

File:OR17026figA18.jpg
Figure A18    Monthly recharge the Solway Tweed RBMD for historic simulated and changes to monthly values for 2020s, 2050s and 2080s for all ensembles.
File:OR17026figA19.jpg
Figure A19    Minimum, average and maximum recharge the Solway Tweed RBMD for historic simulated and for 2020s, 2050s and 2080s.

Table A1 shows that average recharge for all the 11 ensembles is very similar for the historical simulation and the 2020s and 2050s. An increase is observed for the 2080s. As would be expected range (difference between minimum and maximum) increases between historical simulation and future forecasts. So it is worth noting that under some future scenarios (afixj and afixo) recharge volume decreases compared to the historical simulation.

A5.3 RBMD 3 - Northumbria

There is relative low recharge in the historical simulation (Figure A20). For the 2020s, 2050s and the 2080s there is a mixed response (some decreases and some increases over the year). The recharge totals increase from the historical simulation to the 2020s, reducing for the 2050s and increasing again in the 2080s (see Figure A21).

This is a small catchment so variability in average recharge volumes is limited (Table A2) with possibly a reduction in reduction from historical simulation to future.

File:OR17026figA20.jpg
Figure A20    Monthly recharge the Northumbria RBMD for historic simulated and changes to monthly values for 2020s, 2050s and 2080s for all ensembles.
File:OR17026figA21.jpg
Figure A21    Minimum, average and maximum recharge the Northumbria RBMD for historic simulated and for 2020s, 2050s and 2080s.

A5.4 RBMD 4 - Humber

There is a relative low recharge in the historical simulation (Figure A22). For the 2020s mixed response (some decreases and some increases over the year). The 2050s demonstrated increases earlier in the year, mixed in the summer, reduction in July, August, September, and increases in October, November and December. The 2080s follow a similar pattern to the 2050s. Note: due to lower historical simulated recharge then variability is perhaps more muted. The recharge totals increase from the historical simulation to the 2020s, reducing for the 2050s and increasing again in the 2080s (see Figure A23).

Table A3 shows that average recharge for all the 11 ensembles is very similar for the historical simulation and the 2020s and 2050s. However a marked increase is observed for the 2080s.

File:OR17026figA22.jpg
Figure A22    Monthly recharge the Humber RBMD for historic simulated and changes to monthly values for 2020s, 2050s and 2080s for all ensembles.
File:OR17026figA23.jpg
Figure A23    Minimum, average and maximum recharge the Humber RBMD for historic simulated and for 2020s, 2050s and 2080s.
Table A1    Recharge volumes for Catchment 2: Solway Tweed.
afgcx afixa afixc afixh afici afixj afixk afixl afixm afixo afixq Min. Max. Average
1961–1990 139.55 136.35 142.67 145.82 142.11 137.94 139.68 145.21 140.20 143.78 141.58 136.35 145.82 141.35
1971–2000 140.76 138.95 142.81 148.04 139.00 138.37 143.13 144.50 140.10 144.52 139.51 138.37 148.04 141.79
20s 149.59 142.24 145.40 158.02 142.39 138.72 139.85 150.79 144.63 137.57 150.39 137.57 158.02 145.42
50s 150.07 144.33 144.99 152.82 149.35 135.77 132.70 148.12 144.07 132.74 142.07 132.70 152.82 143.37
80s 149.56 147.08 145.34 162.15 152.08 144.29 140.60 149.53 139.42 142.80 152.33 139.42 162.15 147.74

Note: Recharge values in 106 x Ml/day
Table A2    Recharge volumes for Catchment 3: Northumbria.
afgcx afixa afixc afixh afici afixj afixk afixl afixm afixo afixq Min. Max. Average
1961–1990 34.39 33.95 35.73 37.02 34.86 34.35 33.77 36.47 34.69 35.87 34.64 33.77 37.02 35.07
1971–2000 35.48 33.57 35.54 37.34 35.30 36.12 34.48 36.58 33.64 34.96 33.55 33.55 37.34 35.14
20s 38.14 32.82 37.34 38.64 33.47 33.41 35.37 38.03 38.19 32.34 36.31 32.34 38.64 35.82
50s 34.46 33.13 34.02 36.02 35.36 32.77 30.49 36.11 36.48 31.55 34.05 30.49 36.48 34.04
80s 33.95 35.30 36.41 39.03 38.67 33.74 32.75 35.28 36.24 33.53 35.44 32.75 39.03 35.49

Note: Recharge values in 106 x Ml/day
Table A3    Recharge volumes for Catchment 4: Humber.
afgcx afixa afixc afixh afici afixj afixk afixl afixm afixo afixq Min. Max. Average
1961–1990 112.41 108.98 118.00 123.10 115.07 109.50 112.26 121.23 112.65 117.86 112.63 108.98 123.10 114.88
1971-2000 116.05 107.27 119.98 127.61 118.39 116.32 118.13 122.55 109.22 114.74 107.39 107.27 127.61 116.15
20s 122.61 102.30 131.78 129.58 106.31 108.86 114.70 129.74 120.20 107.27 116.49 102.30 131.78 117.26
50s 116.75 106.98 124.18 131.78 118.36 105.00 100.14 121.62 118.44 102.94 115.79 100.14 131.78 114.73
80s 119.71 113.01 134.43 140.09 126.80 107.54 107.76 122.77 124.47 114.74 119.42 107.54 140.09 120.98

Note: Recharge values in 106 x Ml/day

A5.5 RBMD 5 - Anglian

There is relative low recharge in the historical simulation (Figure A24). For the 2020s there are increases in recharge season, but with some ensembles showing lower recharge. The summer months exhibit a very flat response. The 2050s and 2080s very similar pattern, but with 2080s showing increase in variability from April to September. The recharge totals increase from the historical simulation to the 2020s, increasing for the 2050s and increasing markedly in the 2080s (see Figure A25).

Table A4 shows that average recharge for all the 11 ensembles is very similar for the historical simulation and the 2020s and 2050s. Similarly for the Humber RBMD, a significant increase is observed for the 2080s.

File:OR17026figA24.jpg
Figure A24    Monthly recharge the Anglian RBMD for historic simulated and changes to monthly values for 2020s, 2050s and 2080s for all ensembles.
File:OR17026figA25.jpg
Figure A25    Minimum, average and maximum recharge the Anglia RBMD for historic simulated and for 2020s, 2050s and 2080s.

A5.6 RBMD 6 - Thames

The recharge is moderate in the historical simulation (Figure A26). For the future scenarios, the monthly variability of change in recharge values increases for all three time slices with January to March and November and December exhibiting the greatest changes. The recharge totals increase from the historical simulation to the 2020s, increasing again to the 2050s and onwards to 2080s (see Figure A27).

Table A5 shows that average recharge for all the 11 ensembles is very similar for the historical simulation and the 2020s and 2050s. Again for the Humber and Anglian RBMDs, a significant increase is observed for the 2080s.

File:OR17026figA26.jpg
Figure A26    Monthly recharge the Thames RBMD for historic simulated and changes to monthly values for 2020s, 2050s and 2080s for all ensembles.
File:OR17026figA27.jpg
Figure A27    Minimum, average and maximum recharge the Thames RBMD for historic simulated and for 2020s, 2050s and 2080s.

A5.7 RBMD 7 - South East

The recharge is high in the historical simulation (Figure 28). For the ensembles, the monthly variability of change in recharge values increases for all three time slices with January to March and November and December exhibiting the greatest changes. Some of the ensembles show a reduction in September and October. The recharge totals increase from the historical simulation to the 2020s, increasing for the 2050s and increasing again in the 2080s (see Figure A29).

Table A6 shows that average recharge for all the 11 ensembles increases from historical simulation marginally to the 2020s and 2050s. Following a similar pattern for the other larger RBMDs, a significant increase is observed for the 2080s.

File:OR17026figA28.jpg
Figure A28    Monthly recharge the South east RBMD for historic simulated and changes to monthly values for 2020s, 2050s and 2080s for all ensembles.
File:OR17026figA29.jpg
Figure A29    Minimum, average and maximum recharge the South-east RBMD for historic simulated and for 2020s, 2050s and 2080s.
Table A4    Recharge volumes for Catchment 5: Anglian.
afgcx afixa afixc afixh afici afixj afixk afixl afixm afixo afixq Min. Max. Average
1961–1990 50.84 47.86 57.66 62.12 53.83 48.30 52.58 58.18 51.49 55.62 51.31 47.86 62.12 53.62
1971–2000 56.54 47.26 60.56 64.95 55.69 55.06 56.79 58.98 49.83 55.21 53.22 47.26 64.95 55.82
20s 57.40 40.86 64.22 66.11 46.06 51.18 55.02 62.26 55.05 57.05 54.24 40.86 66.11 55.40
50s 52.36 46.75 69.41 72.75 56.21 45.48 46.07 52.75 57.85 42.94 57.24 42.94 72.75 54.53
80s 60.31 53.01 71.82 81.37 70.67 50.62 55.90 64.39 65.45 59.97 61.97 50.62 81.37 63.22

Note: Recharge values in 106 x Ml/day
Table A5    Recharge volumes for Catchment 6: Thames.
afgcx afixa afixc afixh afici afixj afixk afixl afixm afixo afixq Min. Max. Average
1961–1990 63.69 62.98 69.27 73.05 66.99 62.78 64.65 69.43 63.67 67.85 64.16 62.78 73.05 66.23
1971–2000 69.05 62.16 68.18 78.81 65.74 66.59 67.59 66.13 60.43 69.67 67.23 60.43 78.81 67.42
20s 67.70 54.82 74.84 80.72 62.00 64.77 64.99 75.64 62.23 71.78 62.96 54.82 80.72 67.49
50s 65.53 61.04 77.21 86.57 68.49 56.28 60.90 65.56 69.08 59.53 68.99 56.28 86.57 67.20
80s 74.65 62.53 82.65 93.39 83.39 63.01 66.50 72.57 64.53 70.82 73.65 62.53 93.39 73.43

Note: Recharge values in 106 x Ml/day
Table A6    Recharge volumes for Catchment 7: South-East.
afgcx afixa afixc afixh afici afixj afixk afixl afixm afixo afixq Min. Max. Average
1961–1990 45.96 45.22 48.47 50.39 47.77 46.17 45.84 48.07 45.98 48.02 46.05 45.22 50.39 47.08
1971–2000 48.20 47.21 47.41 53.61 45.42 49.10 47.35 46.44 43.10 50.77 47.69 43.10 53.61 47.84
20s 48.82 41.01 51.79 56.52 45.91 47.08 47.37 54.02 43.35 50.37 45.56 41.01 56.52 48.34
50s 47.14 46.56 53.91 59.19 50.80 44.40 47.77 48.57 49.22 46.17 51.75 44.40 59.19 49.59
80s 53.73 49.09 58.39 64.19 61.08 50.68 50.95 51.78 42.79 51.80 55.23 42.79 64.19 53.61

Note: Recharge values in 106 x Ml/day

A5.8 RBMD 8 - South West

The recharge is high in the historical simulation (Figure A30). For the ensembles, the monthly variability of change in recharge values increases for all three time slices with January to March and November and December exhibiting the greatest changes. Some of the ensembles show a reduction in September and October. The 2050s and 2080s show a reduction in recharge between April and October. The recharge totals increase from the historical simulation to the 2020s, reducing for the 2050s and increasing again in the 2080s (see Figure A31).

Table A7 shows that average recharge for all the 11 ensembles increases from historical simulation marginally to the 2020s and 2050s. Again, a significant increase is observed for the 2080s.

File:OR17026figA30.jpg
Figure A30    Monthly recharge the South-west RBMD for historic simulated and changes to monthly values for 2020s, 2050s and 2080s for all ensembles.
File:OR17026figA31.jpg
Figure A31    Minimum, average and maximum recharge the South-west RBMD for historic simulated and for 2020s, 2050s and 2080s.

A5.9 RBMD 9 - Severn

The recharge is high in the historical simulation (Figure A32). For the ensembles, the monthly variability of change in recharge values increases for all three time slices with January to March and November and December exhibiting the greatest changes. Some of the ensembles show a reduction in September and October. The 2050s and 2080s show a reduction in recharge between April and October. The recharge totals increase from the historical simulation to the 2020s, reducing for the 2050s and increasing again in the 2080s (see Figure A33).

Table A8 shows that average recharge for all the 11 ensembles is very similar for the historical simulation and the 2020s and 2050s. As is observed for the other RBMDs an increase is observed for the 2080s.

File:OR17026figA32.jpg
Figure A32    Monthly recharge the Severn RBMD for historic simulated and changes to monthly values for 2020s, 2050s and 2080s for all ensembles.
File:OR17026figA33.jpg
Figure A33    Minimum, average and maximum recharge the Severn RBMD for historic simulated and for 2020s, 2050s and 2080s.

A5.10 RBMD 10 - Western Wales

The recharge is very high in the historical simulation (Figure A34). For the 2020s variability with the majority of the ensembles increasing January and February as well as October, November and December. For both the 2050s and 2080s then the trend appears to be from an increase to a decrease from January to September followed by a sharp increase from September to the end of the year. The recharge totals increase from the historical simulation to the 2020s, reducing for the 2050s and increasing again in the 2080s (see Figure A35).

Table A9 shows that average recharge for all the 11 ensembles increases from historical simulation marginally to the 2020s and 2050s. A significant increase is observed for the 2080s.

File:OR17026figA34.jpg
Figure A34    Monthly recharge the Western Wales RBMD for historic simulated and changes to monthly values for 2020s, 2050s and 2080s for all ensembles.
File:OR17026figA35.jpg
Figure A35    Minimum, average and maximum recharge the Western Wales RBMD for historic simulated and for 2020s, 2050s and 2080s.
Table A7    Recharge volumes for Catchment 8: South-West.
afgcx afixa afixc afixh afici afixj afixk afixl afixm afixo afixq Min. Max. Average
1961–1990 154.69 152.97 158.71 162.35 159.66 156.11 153.76 159.69 155.22 157.62 154.81 152.97 162.35 156.87
1971–2000 156.68 158.88 155.93 170.01 155.08 162.05 158.47 155.52 153.06 158.78 152.32 152.32 170.01 157.89
20s 153.03 149.26 166.05 175.29 153.73 154.74 151.42 169.74 149.44 159.02 156.34 149.26 175.29 158.01
50s 156.12 159.64 167.37 177.37 163.05 147.21 146.94 159.47 160.18 148.84 162.43 146.94 177.37 158.97
80s 170.35 164.97 177.58 191.92 178.89 161.27 157.72 156.82 143.79 162.88 172.26 143.79 191.92 167.13

Note: Recharge values in 106 x Ml/day
Table A8    Recharge volumes for Catchment 9: Severn.
afgcx afixa afixc afixh afici afixj afixk afixl afixm afixo afixq Min. Max. Average
1961–1990 158.39 156.16 163.54 168.44 161.83 157.68 158.92 166.12 159.26 163.59 158.83 156.16 168.44 161.16
1971–2000 162.16 154.58 160.16 179.36 161.77 158.94 164.56 160.80 156.41 164.13 155.29 154.58 179.36 161.65
20s 151.68 148.26 171.90 183.79 152.34 153.92 155.81 175.50 161.40 162.12 159.92 148.26 183.79 161.51
50s 159.11 155.94 169.67 183.10 164.57 150.28 147.92 168.13 162.74 146.19 165.00 146.19 183.10 161.15
80s 166.10 159.95 176.35 196.77 174.46 153.73 151.98 163.66 161.09 160.36 164.95 151.98 196.77 166.31

Note: Recharge values in 106 x Ml/day
Table A9    Recharge volumes for Catchment 10: Western Wales.
afgcx afixa afixc afixh afici afixj afixk afixl afixm afixo afixq Min. Max. Average
1961–1990 164.21 162.21 167.17 168.77 167.21 165.04 163.90 168.14 164.86 167.42 165.41 162.21 168.77 165.85
1971–2000 167.30 166.91 164.29 175.00 167.27 165.27 168.32 163.45 168.16 168.26 163.05 163.05 175.00 167.03
20s 161.28 169.65 168.69 181.57 161.92 166.95 163.57 174.89 167.23 167.68 175.69 161.28 181.57 169.01
50s 169.20 175.72 170.52 176.69 170.94 160.42 160.04 173.59 172.67 160.64 173.32 160.04 176.69 169.43
80s 171.40 180.60 169.77 189.26 174.47 167.93 165.09 170.09 167.56 174.46 175.95 165.09 189.26 173.33

Note: Recharge values in 106 x Ml/day

A5.11 RBMD 11 - Dee

The recharge is high in the historical simulation (Figure A36). For the ensembles, the monthly variability of change in recharge values increases for all three time slices with January to March and November and December exhibiting the greatest changes. Some of the ensembles show a reduction in September and October. The 2050s and 2080s show a reduction n recharge between April and October. The recharge totals increase from the historical simulation to the 2020s, reducing for the 2050s and increasing again in the 2080s (see Figure A37).

This is a small catchment so variability in average recharge is limited (see Table A10) with possibly a reduction in reduction from historical simulation to future.

File:OR17026figA36.jpg
Figure A36    Monthly recharge the Dee RBMD for historic simulated and changes to monthly values for 2020s, 2050s and 2080s for all ensembles.
File:OR17026figA37.jpg
Figure A37    Minimum, average and maximum recharge the Dee RBMD for historic simulated and for 2020s, 2050s and 2080s.

A5.12 RBMD 12 - North West

The recharge is high in the historical simulation (Figure 38). For the 2020s variability with the majority of the ensembles increasing January and February as well as October, November and December. For both the 2050s and 2080s then the trend appears to be from an increase to a decrease from January to September followed by a sharp increase from September to the end of the year. The recharge totals increase from the historical simulation to the 2020s, reducing for the 2050s and increasing again in the 2080s (see Figure A39).

Table A11 shows that average recharge for all the 11 ensembles increases from historical simulation marginally to the 2020s and 2050s. A significant increase is observed for the 2080s.

File:OR17026figA38.jpg
Figure A38    Monthly recharge the North-west RBMD for historic simulated and changes to monthly values for 2020s, 2050s and 2080s for all ensembles.
File:OR17026figA39.jpg
Figure A39    Minimum, average and maximum recharge the North-west RBMD for historic simulated and for 2020s, 2050s and 2080s.
Table A10    Recharge volumes for Catchment 11: Dee.
afgcx afixa afixc afixh afici afixj afixk afixl afixm afixo afixq Min. Max. Average
1961–1990 16.27 16.22 16.72 17.20 16.62 16.16 16.29 17.00 16.45 16.86 16.40 16.16 17.20 16.56
1971–2000 16.66 15.80 16.41 17.69 17.15 16.19 16.67 16.57 16.49 16.88 15.81 15.80 17.69 16.58
20s 15.68 15.64 17.21 18.17 15.92 15.56 16.00 17.36 17.00 15.69 16.46 15.56 18.17 16.43
50s 16.10 15.84 16.57 17.83 16.25 15.08 14.61 16.64 16.64 14.95 16.28 14.61 17.83 16.07
80s 16.21 16.27 16.94 18.72 16.69 14.70 14.39 16.23 16.84 15.61 15.74 14.39 18.72 16.21

Note: Recharge values in 106 x Ml/day
Table A11    Recharge volumes for Catchment 12: North-West.
afgcx afixa afixc afixh afici afixj afixk afixl afixm afixo afixq Min. Max. Average
1961–1990 105.24 102.95 107.38 109.71 107.93 104.77 105.67 109.42 105.76 108.67 106.99 102.95 109.71 106.77
1971–2000 106.12 105.32 108.08 113.47 109.50 105.05 108.34 108.32 109.14 109.39 104.03 104.03 113.47 107.89
20s 110.55 107.53 109.57 117.70 106.13 105.22 105.04 114.72 112.13 105.59 115.18 105.04 117.70 109.94
50s 114.34 111.27 110.51 117.64 111.08 103.00 103.01 110.64 113.48 104.72 107.71 103.00 117.64 109.76
80s 111.53 116.35 111.81 124.74 111.90 107.76 105.14 114.58 112.39 112.53 114.99 105.14 124.74 113.07

Note: Recharge values in 106 x Ml/day
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