Methods Used in a Mass-Balance Study of Holocene Sediment Accumulation on the ...
371
010·' m
~1Io-2m
-2 to-3m
•
·3toa41m
--4to-Sm
~
-6lo--6m
oi l
-6 to-7 m
.,
1
-7 to-6 m
-8to-9m
t .gto·l0m
,.,'"
... 'ii
4 iiiiP
-1 0 to -11 m
-11 to-12 m
'"
, . .
-12 to -13 m
I=, ~
-'3ID-1 4m
-
n,
-1 4m-15m
-
i...., ..
""
-1510 -'6 m
""
"'"
Iotal VOlume
-1 00
-80
-60
-40
-20
20
4ll
60
80
100
__ lOOnln%
o MacGRIDZO (50%) 300·300 grid ce .. - 8 OCSOrvatJOn points
•
MacGRIDZO (33%) 300·300 grid cello - 8 obseM1ion poInto
o MacGRIDZO (100%) 300·300 gOd ..... - I oboerva_ po&1l
mI MacGRIDZO (100%) so-so grid celIS - 1 """""ObOtl poont
•
MacGRIDZO (100%) SO·SO grid cello - 8 """",,_Iioo poonts
Fig.8 Comparison of results
obtained from volume calculations with the MacGRIDZO computer program
on sheet 2716 (Elsfteth). The
differences refer firstly to
volume calculations using
different numbers of boreholes (100,50 and 33% of the
total number of boreholes).
Secondly they are affected by
calculations using one or
eight depth values per grid
node, and 301 grid lines in
the X and Y directions
variations of the parameters included: (1) number of boreholes (100,50 and
33% of the total number of boreholes), (2) boreholes per grid node, and (3)
line spacing. Again the differences in the depth intervals between 0 to -10 m
NN are insignificant (Fig. 8). Below -10 m NN large positive deviations were
obtained. This is especially true for calculations that use the depth value of one
single borehole per grid node. Probably this has to be attributed to the fact that
in this case the calculation of a single grid node is dominated by data obtained
from a small number of boreholes that intersected the base of the Holocene below -10m NN. In the case of gridding with borehole data using 8 holes per grid
node, a single borehole with the base Holocene below -10 m NN has only a minor influence on depth obtained at the grid node. Further, it should be pointed
out that calculations of the total volume below NN with 100,50 and 33% of the
total number of boreholes show deviations of less than 3%. Therefore it can be
concluded that, with the methods applied, a relatively small data base is sufficient for reliable determinations of volumes of the coastal Holocene.
371
010·' m
~1Io-2m
-2 to-3m
•
·3toa41m
--4to-Sm
~
-6lo--6m
oi l
-6 to-7 m
.,
1
-7 to-6 m
-8to-9m
t .gto·l0m
,.,'"
... 'ii
4 iiiiP
-1 0 to -11 m
-11 to-12 m
'"
, . .
-12 to -13 m
I=, ~
-'3ID-1 4m
-
n,
-1 4m-15m
-
i...., ..
""
-1510 -'6 m
""
"'"
Iotal VOlume
-1 00
-80
-60
-40
-20
20
4ll
60
80
100
__ lOOnln%
o MacGRIDZO (50%) 300·300 grid ce .. - 8 OCSOrvatJOn points
•
MacGRIDZO (33%) 300·300 grid cello - 8 obseM1ion poInto
o MacGRIDZO (100%) 300·300 gOd ..... - I oboerva_ po&1l
mI MacGRIDZO (100%) so-so grid celIS - 1 """""ObOtl poont
•
MacGRIDZO (100%) SO·SO grid cello - 8 """",,_Iioo poonts
Fig.8 Comparison of results
obtained from volume calculations with the MacGRIDZO computer program
on sheet 2716 (Elsfteth). The
differences refer firstly to
volume calculations using
different numbers of boreholes (100,50 and 33% of the
total number of boreholes).
Secondly they are affected by
calculations using one or
eight depth values per grid
node, and 301 grid lines in
the X and Y directions
variations of the parameters included: (1) number of boreholes (100,50 and
33% of the total number of boreholes), (2) boreholes per grid node, and (3)
line spacing. Again the differences in the depth intervals between 0 to -10 m
NN are insignificant (Fig. 8). Below -10 m NN large positive deviations were
obtained. This is especially true for calculations that use the depth value of one
single borehole per grid node. Probably this has to be attributed to the fact that
in this case the calculation of a single grid node is dominated by data obtained
from a small number of boreholes that intersected the base of the Holocene below -10m NN. In the case of gridding with borehole data using 8 holes per grid
node, a single borehole with the base Holocene below -10 m NN has only a minor influence on depth obtained at the grid node. Further, it should be pointed
out that calculations of the total volume below NN with 100,50 and 33% of the
total number of boreholes show deviations of less than 3%. Therefore it can be
concluded that, with the methods applied, a relatively small data base is sufficient for reliable determinations of volumes of the coastal Holocene.