17 In Situ Settling Velocities and Concentrations of Suspended Sediment in Spill Plumes
17.4.2
Concentration
185
The natural concentration of suspended sediment in the 0resund is very low, values of
1 to 2 mg 1-1 being the norm (Pejrup and Larsen 1994 During dredging, concentrations can rise to several hundred milligrams per litre in the area surrounding the dredger
depending on currents and the dredged material, decreasing rapidly downstream of
the source. Suspended sediment concentrations were measured on two different occasions, on 14 May 1996 and 2 October 1996. Figure 17.3a,b show plots of model scenarios
based on MIKE 21 (DBI software). The measured values are marked by dots. The data
were used to test the consistency of the model results. Concentrations are seen to vary
(Gridspacing 500m)
70
68
66
64
62
60
58
E
56
8
'" 54
'" c
.~
~ 52
:g
8
50
48
46
44
42
40
38
36
65
67
69
71
73
75
77
79
81
83
85
87
89
91
93
Fig. 17.3 b. Hindcast spill scenario from 2 October 1996
17.4.2
Concentration
185
The natural concentration of suspended sediment in the 0resund is very low, values of
1 to 2 mg 1-1 being the norm (Pejrup and Larsen 1994 During dredging, concentrations can rise to several hundred milligrams per litre in the area surrounding the dredger
depending on currents and the dredged material, decreasing rapidly downstream of
the source. Suspended sediment concentrations were measured on two different occasions, on 14 May 1996 and 2 October 1996. Figure 17.3a,b show plots of model scenarios
based on MIKE 21 (DBI software). The measured values are marked by dots. The data
were used to test the consistency of the model results. Concentrations are seen to vary
(Gridspacing 500m)
70
68
66
64
62
60
58
E
56
8
'" 54
'" c
.~
~ 52
:g
8
50
48
46
44
42
40
38
36
65
67
69
71
73
75
77
79
81
83
85
87
89
91
93
Fig. 17.3 b. Hindcast spill scenario from 2 October 1996