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 /
ha (£
ha-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 |
