Publication - Independent report

Developing a method to estimate the costs of soil erosion in high-risk Scottish catchments: final report

Report from a project which developed and used an ecosystem service framework approach to estimate the costs of soil erosion in Scotland, for five study catchments.

273 page PDF

4.7 MB

273 page PDF

4.7 MB

Contents
Developing a method to estimate the costs of soil erosion in high-risk Scottish catchments: final report
7. Modelling results

273 page PDF

4.7 MB

7. Modelling results

The results for each case study catchment and the national picture are given below. All figures are on a ‘per annum’ basis. Costs are itemised to show detail, then summed to give:

  • Total on-site costs;
  • Total off site costs (with drinking water costs);
  • Total off-site costs (without drinking water costs);
  • Total costs (with drinking water costs);
  • Total costs (without drinking water costs).

At present, the Ugie is the only catchment where drinking water is abstracted (so incurring greater costs associated with water treatment). However, these costs have also been presented for the other 4 catchments, to reflect any future plans to abstract drinking water from these catchments

The annual costs of soil erosion in each catchment are given in Tables 33, 34, 35, 36 and 37 for the Ugie, Pow, Girvan, Esk and Tweed catchments respectively. Summary tables for all catchments are given in Table 38

Detailed tables of annual costs for the Ugie catchment (as an illustration) are shown in Appendix 9.

7.1. Catchment 1: Ugie

Table 33. Annual costs of soil erosion in the Ugie catchment
Physical data Total Catchment area (ha) 29,878
Total areas at risk within catchment (ha) 3,632
Proportion at risk (%) 12%
Soil depth loss (mm yr-1) 0.29
Catchment soil erosion (t yr-1) 7,392
Average catchment soil erosion (t ha-1 yr-1) 0.25
Soil N loss (t yr-1) 54
Soil P loss (t yr-1) 19
Soil K loss (t yr-1) 3
Soil C loss (t yr-1) 1077
On-site costs Total catchment productivity loss due to erosion (£) 8,829
Catchment productivity loss due to erosion in risk area (£ ha-1 ) 2.4
Total catchment productivity loss due to erosion in total area (£ ha-1 ) 0.3
Total catchment N loss cost due to erosion (£) 36,328
Average catchment N loss cost due to erosion (£ ha-1 risk area) 10
Average catchment N loss cost due to erosion (£ ha-1 category area) 1.2
Total catchment P loss cost due to erosion (£) 13,076
Average catchment P loss cost due to erosion (£ ha-1 risk area) 3.60
Average catchment P loss cost due to erosion (£ ha-1 category area) 0.44
Total catchment K loss cost due to erosion (£) 1,329
Average catchment K loss cost due to erosion (£ ha-1 risk area) 0.37
Average catchment P loss cost due to erosion (£ ha-1 category area) 0.04
Total catchment C loss cost due to erosion (£) 718
Average catchment C loss cost due to erosion (£ ha-1 risk area) 0.20
Average catchment C loss cost due to erosion (£ ha-1 category area) 0.02
Off-site costs Cost of sediment removal in rivers & canals (£) 38,066
Cost of sediment removal in drinking water (£) 133,048
Cost of N in rivers and lakes (£) 10,302
Cost of N in transitional waters (£) 542
Cost of N in drinking water (£) 11,007
Cost of P in freshwater lakes (£) 31,902
GHG cost of soil C loss (£) 53,767
Total costs Total onsite cost 60,281
Total offsite cost (with drinking water costs) 278,634
Total offsite cost (without drinking water cost) 134,580
Total costs with drinking water costs 338,915
Total costs without drinking water 194,861
Total cost / ha (without drinking water) (£ ha-1 ) 6.52
Total cost / ha (with drinking water) (£ ha-1 ) 11.34

7.2. Catchment 2: The Pow

Table 34. Annual costs of soil erosion in the Pow catchment
Physical data Total Catchment area (ha) 4,332
Total areas at risk within catchment (ha) 511
Proportion at risk (%) 12%
Soil depth loss (mm yr-1) 0.21
Catchment soil erosion (t yr-1) 1,016
Average catchment soil erosion (t ha-1 yr-1) 0.25
Soil N loss (t yr-1) 4
Soil P loss (t yr-1) 2
Soil K loss (t yr-1) 0
Soil C loss (t yr-1) 81
On-site costs Total catchment productivity loss due to erosion (£) 1,042
Catchment productivity loss due to erosion in risk area (£ ha-1 ) 2
Total catchment productivity loss due to erosion in total area (£ ha-1 ) 0.2
Total catchment N loss cost due to erosion (£) 3,010
Average catchment N loss cost due to erosion (£ ha-1 risk area) 6
Average catchment N loss cost due to erosion (£ ha-1 category area) 0.7
Total catchment P loss cost due to erosion (£) 1,465
Average catchment P loss cost due to erosion (£ ha-1 risk area) 2.86
Average catchment P loss cost due to erosion (£ ha-1 category area) 0.34
Total catchment K loss cost due to erosion (£) 154
Average catchment K loss cost due to erosion (£ ha-1 risk area) 0.30
Average catchment P loss cost due to erosion (£ ha-1 category area) 0.04
Total catchment C loss cost due to erosion (£) 54
Average catchment C loss cost due to erosion (£ ha-1 risk area) 0.11
Average catchment C loss cost due to erosion (£ ha-1 category area) 0.01
Off-site costs Cost of sediment removal in rivers & canals (£) 5,230
Cost of sediment removal in drinking water (£) 18,280
Cost of N in rivers and lakes (£) 854
Cost of N in transitional waters (£) 45
Cost of N in drinking water (£) 912
Cost of P in freshwater lakes (£) 3,573
GHG cost of soil C loss (£) 4,059
Total costs Total onsite cost 5,724
Total offsite cost (with drinking water costs) 32,953
Total offsite cost (without drinking water cost) 13,761
Total costs with drinking water costs 38,677
Total costs without drinking water 19,485
Total cost / ha (without drinking water) (£ ha-1 ) 4.50
Total cost / ha (with drinking water) (£ ha-1 ) 8.93

7.3. Catchment 3: Girvan

Table 35. Annual costs of soil erosion in the Girvan catchment
Physical data Total Catchment area (ha) 23,393
Total areas at risk within catchment (ha) 3,533
Proportion at risk (%) 15%
Soil depth loss (mm yr-1) 0.20
Catchment soil erosion (t yr-1) 4,652
Average catchment soil erosion (t ha-1 yr-1) 0.20
Soil N loss (t yr-1) 33
Soil P loss (t yr-1) 11
Soil K loss (t yr-1) 2
Soil C loss (t yr-1) 605
On-site costs Total catchment productivity loss due to erosion (£) 4,236
Catchment productivity loss due to erosion in risk area (£ ha-1) 1.20
Total catchment productivity loss due to erosion in total area (£ ha-1) 0.18
Total catchment N loss cost due to erosion (£) 22,182
Average catchment N loss cost due to erosion (£ ha-1 risk area) 6.28
Average catchment N loss cost due to erosion (£ ha-1 category area) 0.95
Total catchment P loss cost due to erosion (£) 7,236
Average catchment P loss cost due to erosion (£ ha-1 risk area) 2.05
Average catchment P loss cost due to erosion (£ ha-1 category area) 0.31
Total catchment K loss cost due to erosion (£) 881
Average catchment K loss cost due to erosion (£ ha-1 risk area) 0.25
Average catchment P loss cost due to erosion (£ ha-1 category area) 0.04
Total catchment C loss cost due to erosion (£) 403
Average catchment C loss cost due to erosion (£ ha-1 risk area) 0.11
Average catchment C loss cost due to erosion (£ ha-1 category area) 0.02
Off-site costs Cost of sediment removal in rivers & canals (£) 23,959
Cost of sediment removal in drinking water (£) 83,740
Cost of N in rivers and lakes (£) 6,291
Cost of N in transitional waters (£) 331
Cost of N in drinking water (£) 6,721
Cost of P in freshwater lakes (£) 17,654
GHG cost of soil C loss (£) 30,187
Total costs Total onsite cost 34,939
Total offsite cost (with drinking water costs) 168,882
Total offsite cost (without drinking water cost) 78,421
Total costs with drinking water costs 203,821
Total costs without drinking water 113,360
Total cost / ha (without drinking water) (£ ha-1) 4.85
Total cost / ha (with drinking water) (£ ha-1) 8.71

7.4. Catchment 4: The Esk

Table 36. Annual costs of soil erosion in the Esk catchment
Physical data Total Catchment area (ha) 51,763
Total areas at risk within catchment (ha) 8,834
Proportion at risk (%) 0.17
Soil depth loss (mm yr-1) 0.20
Catchment soil erosion (t yr-1) 9,140
Average catchment soil erosion (t ha-1 yr-1) 0.18
Soil N loss (t yr-1) 71
Soil P loss (t yr-1) 19
Soil K loss (t yr-1) 5
Soil C loss (t yr-1) 1,680
On-site costs Total catchment productivity loss due to erosion (£) 11,196
Catchment productivity loss due to erosion in risk area (£ ha-1 ) 1.27
Total catchment productivity loss due to erosion in total area (£ ha-1 ) 0.22
Total catchment N loss cost due to erosion (£) 47,302
Average catchment N loss cost due to erosion (£ ha-1 risk area) 5.35
Average catchment N loss cost due to erosion (£ ha-1 category area) 0.91
Total catchment P loss cost due to erosion (£) 12,600
Average catchment P loss cost due to erosion (£ ha-1 risk area) 1.43
Average catchment P loss cost due to erosion (£ ha-1 category area) 0.24
Total catchment K loss cost due to erosion (£) 2,125
Average catchment K loss cost due to erosion (£ ha-1 risk area) 0.24
Average catchment P loss cost due to erosion (£ ha-1 category area) 0.04
Total catchment C loss cost due to erosion (£) 1,120
Average catchment C loss cost due to erosion (£ ha-1 risk area) 0.13
Average catchment C loss cost due to erosion (£ ha-1 category area) 0.02
Off-site costs Cost of sediment removal in rivers & canals (£) 47,069
Cost of sediment removal in drinking water (£) 164,511
Cost of N in rivers and lakes (£) 13,414
Cost of N in transitional waters (£) 706
Cost of N in drinking water (£) 14,332
Cost of P in freshwater lakes (£) 30,740
GHG cost of soil C loss (£) 83,831
Total costs Total onsite cost 74,343
Total offsite cost (with drinking water costs) 354,603
Total offsite cost (without drinking water cost) 175,760
Total costs with drinking water costs 428,946
Total costs without drinking water 250,103
Total cost / ha (without drinking water) (£ ha-1 ) 4.83
Total cost / ha (with drinking water) (£ ha-1 ) 8.29

7.5. Catchment 5: The Tweed

Table 37. Annual costs of soil erosion in the Tweed catchment
Physical data Total Catchment area (ha) 351,190
Total areas at risk within catchment (ha) 53,901
Proportion at risk (%) 15%
Soil depth loss (mm yr-1) 0.20
Catchment soil erosion (t yr-1) 66,220
Average catchment soil erosion (t ha-1 yr-1) 0.19
Soil N loss (t yr-1) 525
Soil P loss (t yr-1) 160
Soil K loss (t yr-1) 35
Soil C loss (t yr-1) 10,258
On-site costs Total catchment productivity loss due to erosion (£) 66,941
Catchment productivity loss due to erosion in risk area (£ ha-1 ) 1.24
Total catchment productivity loss due to erosion in total area (£ ha-1 ) 0.19
Total catchment N loss cost due to erosion (£) 351,722
Average catchment N loss cost due to erosion (£ ha-1 risk area) 6.53
Average catchment N loss cost due to erosion (£ ha-1 category area) 1.00
Total catchment P loss cost due to erosion (£) 108,668
Average catchment P loss cost due to erosion (£ ha-1 risk area) 2.02
Average catchment P loss cost due to erosion (£ ha-1 category area) 0.31
Total catchment K loss cost due to erosion (£) 15,684
Average catchment K loss cost due to erosion (£ ha-1 risk area) 0.29
Average catchment P loss cost due to erosion (£ ha-1 category area) 0.04
Total catchment C loss cost due to erosion (£) 6,839
Average catchment C loss cost due to erosion (£ ha-1 risk area) 0.13
Average catchment C loss cost due to erosion (£ ha-1 category area) 0.02
Off-site costs Cost of sediment removal in rivers & canals (£) 341,032
Cost of sediment removal in drinking water (£) 1,191,956
Cost of N in rivers and lakes (£) 99,742
Cost of N in transitional waters (£) 5,250
Cost of N in drinking water (£) 106,566
Cost of P in freshwater lakes (£) 265,117
GHG cost of soil C loss (£) 512,012
Total costs Total onsite cost 549,854
Total offsite cost (with drinking water costs) 2,521,675
Total offsite cost (without drinking water cost) 1,223,153
Total costs with drinking water costs 3,071,529
Total costs without drinking water 1,773,007
Total cost / ha (without drinking water) (£ ha-1 ) 5.05
Total cost / ha (with drinking water) (£ ha-1 ) 8.75

7.6. Summary of catchment scale costs of soil erosion per annum

Tables 38 - 42 summarise the annual costs of soil erosion for each of the 5 case study catchments, by land use type, land use area and Erosion Risk Class. Areas occupied by each land use are given in Appendix 9.1 and in Tables 38 - 42. Table 43 gives an overview of all on-site and off-site costs (£) for all catchments. Table 44 gives the costs per hectare for each of the case study catchments. Finally, Table 45 gives the ranges of output values for all catchments.

Table 38. Summary of annual costs of soil erosion for the Ugie catchment (including drinking water treatment costs) L = Low, M = Moderate, H = High erosion risk class
Ugie Onsite and offsite costs (£ per annum) Total (£) % of total
Land use Area (ha) Erosion Risk Class
L M H Organomineral soils and peats
Urban 320 - - - - - -
Horticulture 13 27 425 - 77 529 0%
Arable intensive 177 129 3,285 19 579 4,013 1%
Arable extensive 12,122 5,712 101,754 546 56,952 164,964 49%
Grassland improved 11,583 5,428 115,582 1,563 27,337 149,910 44%
Grassland unimproved 5 - 2 5 39 46 0%
Rough grassland 1,642 82 2,116 36 7,150 9,384 3%
Forestry 2,297 62 3,070 61 2,558 5,752 2%
Woodland 1,015 54 1,993 39 468 2,554 1%
Wildscape 705 8 153 - 1,603 1,764 1%
Total 29,878 11,501 228,380 2,270 96,764 338,915 100%
% of total 100% 3% 67% 1% 29% 100%
Table 39. Summary of annual costs of soil erosion for the Pow catchment (including drinking water treatment costs) L = Low, M = Moderate, H= High erosion risk class
Pow Onsite and offsite costs (£ per annum) Total (£) % of total
Land use Area (ha) Erosion Risk Class
L M H Organominerals soils and peats
Urban 80 - - - - - -
Horticulture - - - - - - 0%
Arable intensive 48 1 953 8 499 1,462 4%
Arable extensive 2,268 700 18,909 1,172 3,878 24,660 64%
Grassland improved 811 437 7,672 777 290 9,175 24%
Grassland unimproved - - - - - - 0%
Rough grassland 82 5 229 12 23 269 1%
Forestry 715 23 1,678 269 253 2,223 6%
Woodland 293 15 528 110 142 795 2%
Wildscape 35 0 89 - 3 93 0%
Total 4,332 1,181 30,059 2,349 5,088 38,677 100%
% of total 100% 3% 78% 6% 13% 100%
Table 40. Summary of annual costs of soil erosion for the Girvan catchment (including drinking water treatment costs) L = Low, M = Moderate, H = High erosion risk class
Girvan Onsite and offsite costs (£ per annum) Total (£) % of total
Land use Area (ha) Erosion Risk Class
L M H Organomineral soils and peats
Urban 169 - - - - - -
Horticulture - - - - - - 0%
Arable intensive 62 92 814 - - 907 0%
Arable extensive 1,053 384 8,397 805 5,290 14,876 7%
Grassland improved 9,177 2,240 107,825 19,148 6,322 135,536 66%
Grassland unimproved 471 - 517 228 3,463 4,207 2%
Rough grassland 3,964 39 8,033 3,416 11,116 22,604 11%
Forestry 6,438 27 7,483 2,645 9,332 19,486 10%
Woodland 1,537 23 3,315 1,011 401 4,750 2%
Wildscape 521 2 409 48 995 1,454 1%
Total 23,393 2,808 136,794 27,300 36,919 203,821 100%
% of total 100% 1% 67% 13% 18% 100%
Table 41 Summary of annual costs of soil erosion for the Esk catchment (including drinking water treatment costs) L = Low, M = Moderate, H = High erosion risk class
Esk Onsite and offsite costs (£ per annum) Total (£) % of total
Land use Area (ha) Erosion Risk Class
L M H Organo-mineral soils and peats
Urban 358 - - - - - -
Horticulture 16 28 397 - - 425 0%
Arable intensive 923 423 16,669 486 609 18,187 4%
Arable extensive 11,635 2,282 106,438 7,237 17,835 133,792 31%
Grassland improved 6,485 1,348 64,198 13,277 15,415 94,237 22%
Grassland unimproved 302 7 495 498 1,451 2,452 1%
Rough grassland 23,191 85 12,388 28,885 113,130 154,487 36%
Forestry 5,920 31 7,312 3,487 6,807 17,637 4%
Woodland 2,559 24 3,543 631 2,531 6,728 2%
Wildscape 374 2 59 285 657 1,002 0%
Total 51,763 4,229 211,498 54,785 158,435 428,946 100%
% of total 100% 1% 49% 13% 37% 100%
Table 42 Summary of annual costs of soil erosion for the Tweed catchment (including drinking water treatment costs) L = Low, M = Moderate, H = High erosion risk class
Tweed Onsite and offsite costs (£ per annum) Total (£) % of total
Land use Area (ha) Erosion Risk Class
L M H Organo-mineral soils and peats
Urban 2,376 - - - - - -
Horticulture 1 - 24 - - 24 0%
Arable intensive 1,222 852 20,031 451 811 22,146 1%
Arable extensive 53,535 24,455 395,297 19,526 215,433 654,710 21%
Grassland improved 90,152 18,896 1,134,338 141,200 62,463 1,356,897 44%
Grassland unimproved 7,607 254 27,587 20,567 30,704 79,112 3%
Rough grassland 108,624 858 148,702 134,886 402,561 687,008 22%
Forestry 66,807 1,053 87,061 43,008 77,470 208,592 7%
Woodland 15,219 509 30,710 10,296 6,013 47,528 2%
Wildscape 5,648 34 2,473 1,597 11,410 15,513 1%
Total 351,190 46,911 1,846,223 371,531 806,865 3,071,529 100%
% of total 100% 2% 60% 12% 26% 100%
Table 43. Summary of on-site and off-site annual costs (£) for all catchments. L = Low, M = Moderate, H = High erosion risk class
Catchment Area of catchment (ha) On-site (£) Off-site (without drinking water) (£) Off-site (with drinking water) (£) Total (without drinking water) (£) Total (with drinking water) (£)
1. Ugie 29,878 60,281 134,580 278,634 194,861 338,915
2. Pow 4,332 5,724 13,761 32,953 19,485 38,677
3. Girvan 23,393 34,939 78,421 168,882 113,360 203,821
4. Esk 51,763 74,343 175,760 354,603 250,103 428,946
5. Tweed 351,190 549,854 1,223,153 2,521,675 1,773,007 3,071,529
Table 44. Summary of annual costs / haha-1)
Catchment Cost / ha (without drinking water) (£ ha-1 ) Cost / ha (with drinking water) (£ ha-1 )
1. Ugie 6.52 11.34
2. Pow 4.50 8.93
3. Girvan 4.85 8.71
4. Esk 4.83 8.29
5. Tweed 5.05 8.75
Table 45. Ranges of annual values for the 5 study area catchments
Total catchment areas (ha) 4,332 - 351,190
Total areas at risk within catchments (ha) 511 - 53,901
Proportion at risk (%) 12% - 17%
Soil depth loss (mm yr-1) 0.20 - 0.29
Catchment soil erosion (t yr-1) 1,016 - 66,220
Average catchment soil erosion (t ha-1 yr-1) 0.18 - 0.25
Soil N loss (t yr-1) 5 - 525
Soil P loss (t yr-1) 2 - 160
Soil K loss (t yr-1) 0.34 - 35
Soil C loss (t yr-1) 81 - 10,258
On site costs £ 5,724 - 549,854
Off site costs (without drinking water) £ 13,761 - 1,223,153
Off site costs (with drinking water) £ 32,953 - 2,521,675
Total Costs (without drinking water) £ 19,485 - 1,773,007
Total Costs (with drinking water) £ 38,677 - 3,071,529
Cost / ha £ ha-1 (without drinking water) 4.50 - 6.52
Cost / ha £ ha-1 (with drinking water) 8.29 - 11.34

7.7. The national scale

Glenk et al. (2010) tried to estimate the total costs of soil erosion at the national scale, but concluded that a more case study specific approach was needed first (hence this project). The methodology has been applied successfully to the 5 case study catchments. The same approach was then applied at the national scale, running the economic model with national estimates of land use (to determine soil erosion rate) and Soil Erosion Risk Classes (to determine erosion probability).

A summary of the physical results, and the on-site and off-site costs per annum are shown in Table 46.

Table 46. Total annual costs of soil erosion in Scotland
Physical data Total area (ha) 7,108,057
Total areas at risk within catchment (ha) 1,271,735
Proportion at risk (%) 18%
Soil depth loss (mm yr-1) 0.23
Catchment soil erosion (t yr-1) 918,971
Average catchment soil erosion (t ha-1 yr-1) 0.13
Soil N loss (t yr-1) 9,778
Soil P loss (t yr-1) 2,235
Soil K loss (t yr-1) 520
Soil C loss (t yr-1) 218,000
On-site costs Total Scotland productivity loss due to erosion (£) 1,244,832
Scotland productivity loss due to erosion in risk area (£ ha-1) 1.0
Total Scotland productivity loss due to erosion in total area (£ ha-1 ) 0.2
Total Scotland N loss cost due to erosion (£) 6,550,928.0
Average Scotland N loss cost due to erosion (£ ha-1 risk area) 5.2
Average Scotland N loss cost due to erosion (£ ha-1 category area) 0.9
Total Scotland P loss cost due to erosion (£) 1,519,862
Average Scotland P loss cost due to erosion (£ ha-1 risk area) 1.20
Average Scotland P loss cost due to erosion (£ ha-1 category area) 0.21
Total Scotland K loss cost due to erosion (£) 234,178
Average Scotland K loss cost due to erosion (£ ha-1 risk area) 0.18
Average Scotland P loss cost due to erosion (£ ha-1 category area) 0.03
Total Scotland C loss cost due to erosion (£) 145,333
Average Scotland C loss cost due to erosion (£ ha-1 risk area) 0.11
Average Scotland C loss cost due to erosion (£ ha-1 category area) 0.02
Off-site costs Cost of sediment removal in rivers & canals (£) 4,732,699
Cost of sediment removal in drinking water (£) 16,541,473
Cost of N in rivers and lakes (£) 1,857,726
Cost of N in transitional waters (£) 97,775
Cost of N in drinking water (£) 1,984,833
Cost of P in freshwater lakes (£) 3,708,016
GHG cost of soil C loss (£) 10,880,806
Total costs Total onsite cost 9,695,133
Total offsite cost (with drinking water costs) 39,803,328
Total offsite cost (without drinking water cost) 21,277,022
Total costs with drinking water costs 49,498,461
Total costs without drinking water 30,972,155
Total cost / ha (without drinking water) (£ ha-1 ) 4.36
Total cost / ha (with drinking water) (£ ha-1 ) 6.96

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