290
1 __ .. _________ -,;
Land-Ocean SYstems in the Siberian Arctic: Dynamics and History
L
I
I
I
I I
--------------------------------------------t-v
Figure 3: The scheme of flat shore face transformation by continuous retreat of shallow sea shore.
Very simple geometrical considerations show that volume of sediments supplied to the sea by
erosion of the shore face do not depend on inclination and form of it. This is true for both
continuous and limited retreat. Figure 4 shows the scheme of unlimited retreat of concave shore
face. The volume of shore face section eroded according to this scheme is
So the result is the same as for the flat shore face retreat (Figure 3).
The scheme of limited retreat of flat and concave shore faces is shown in Figure 5. The
volume of coast section eroded for both forms of shore face may be calculated as follows.
Concave shore face:
Flat shore face:
So in both cases the eroded volume is determined by the sum of the areas of two trapeziums
and one triangle which are equal in pairs.
In any case the eroded volume is determined by the sum of the areas F 1 and F2 (Figures 2 and
3) as well as by retreat of a vertical wall having the height equal H + hmax . So the V, Hand
hmax are the geometrical parameters needed for calculating of volume eroded. The width of
shore face L (Figure 3) is not needed.
The reasonable choice of hmax value will depend on local bathymetrical conditions. US
scientists calculating the volume of eroded sediments for the western part of Alaska Beaufort
Sea coast used hmax = 2 m at first because a pronounced, and widespread break in slope marks
1 __ .. _________ -,;
Land-Ocean SYstems in the Siberian Arctic: Dynamics and History
L
I
I
I
I I
--------------------------------------------t-v
Figure 3: The scheme of flat shore face transformation by continuous retreat of shallow sea shore.
Very simple geometrical considerations show that volume of sediments supplied to the sea by
erosion of the shore face do not depend on inclination and form of it. This is true for both
continuous and limited retreat. Figure 4 shows the scheme of unlimited retreat of concave shore
face. The volume of shore face section eroded according to this scheme is
So the result is the same as for the flat shore face retreat (Figure 3).
The scheme of limited retreat of flat and concave shore faces is shown in Figure 5. The
volume of coast section eroded for both forms of shore face may be calculated as follows.
Concave shore face:
Flat shore face:
So in both cases the eroded volume is determined by the sum of the areas of two trapeziums
and one triangle which are equal in pairs.
In any case the eroded volume is determined by the sum of the areas F 1 and F2 (Figures 2 and
3) as well as by retreat of a vertical wall having the height equal H + hmax . So the V, Hand
hmax are the geometrical parameters needed for calculating of volume eroded. The width of
shore face L (Figure 3) is not needed.
The reasonable choice of hmax value will depend on local bathymetrical conditions. US
scientists calculating the volume of eroded sediments for the western part of Alaska Beaufort
Sea coast used hmax = 2 m at first because a pronounced, and widespread break in slope marks