244
Land-Ocean Systems in the Siberian Arctic: Dynamics and History
0-28, for Tumatskaya branch (section IV) - 0.24-0.50 and for Olenekskaya branch (section V) -
0.28-0.40.
Of interest are the results of comparison of initial data on water turbidity. It turned out that
variations of daily water turbidity and its values for the main channel - 4.7 km upstream Stolb
Island (section I in Figure 3) and in the Bykovskaya branch (section II) were practically equal.
Thus in 1969, close to a small water content year, and in 1974, close to a large water content
year, the correlation coefficients of relations of daily water turbidity in June-September for
sections I and II turned out to be practically equal to 1. This indicates that it is appropriate to use
the turbidity values in the main channel for estimating the sediment load discharge in the
Bykovskaya branch. Accordingly, a sufficiently close consistency of the variations of mean
monthly turbidity values at permanent hydrometric sections in the other delta arms with that of
the main channel (section I) can be observed. However, for the Tumatskaya (section IV) and
Olenekskaya (section V) branches in separate cases (July, August 1983 and June 1984) a
multiple excess of monthly turbidity compared to its values at the hydrometric section in the
main channel was observed. The reason for this must be in intensive local erosion of plots
located higher than the above mentioned sections, but lower than section I. In any case, it is
necessary to take into account an approximate character of data on the runoff of suspended
sediment load at the delta sections. This is constantly stressed in the editions of the "Annual
Data on the Regime and Water Quality of the Seas and Marine River Mouths".
In view of the observed consistency between the variations of mean monthly water turbidity
at the hydrometric sections in the Lena delta arms and in its main channel, this feature can be
used for calculating the runoff of suspended sediment load at these sections, based on the actual
turbidity data at the hydrometric section in the main channel - 4.7 km upstream Stolb Island and
data on water discharges at the sections in the arms. The comparison of thus calculated mean
monthly discharges of sediment loads at the sections in the delta arms with the measured
sediment load values over the 1977 to 1993 period has shown the correlation coefficients to be
0.89 to 0.96.
The relations of mean monthly suspended sediment load and water discharges at permanent
hydrometric sections in the Lena delta for June-September are subordinated to the power type
dependencies with correlation coefficients within 0.88-0.92. This allows these dependencies to
be used for approximate estimates of the sediment load discharge at the indicated sections (in
case the observations of both water turbidity and discharges are interrupted), based on the level
data at the gauge of Stolb Island and multiyear curves of water discharges for these sections.
It should be stressed that the presented data characterize the discharge of suspended sediment
load at the head of the Lena delta. They cannot serve as a direct indicator of the amount of
suspended material exported to the sea, especially on a seasonal scale. This problem needs
special research as delta processes are rather complicated.
The level of knowledge of the distribution of water and suspended sediment load discharge in
the river deltas of the East-Siberian Sea Basin is very non-unoform. In terms of full-scale
observations all deltas are poorly studied. Only the Kolyma delta in view of the largest
commercial value was investigated using the entire complex of means: full-scale observations,
hydraulic calculations, physical and numerical modeling. This allowed the estimation of the
typical spatial-temporal features of the distribution of water and sediment load discharge at
different characteristics of the water content and sea regime.
The Kolyma delta begins 3 km downstream the Chersky settlement where the river bifurcates
into two branches - Kamennaya and Chernousovskaya. In 10 km downstream from the
Chersky settlement to the left of Kamennaya there is a cross-branch Markhoyanovskaya which
merging with Chemousovskaya, creates the main left arm - the Pokhodskaya branch (Figure
4). The Kamennaya branch is the main delta arm with sea shipping over its entire length. The
Kamennaya and Pokhodskaya branches are connected by the Poperechnaya I and
Land-Ocean Systems in the Siberian Arctic: Dynamics and History
0-28, for Tumatskaya branch (section IV) - 0.24-0.50 and for Olenekskaya branch (section V) -
0.28-0.40.
Of interest are the results of comparison of initial data on water turbidity. It turned out that
variations of daily water turbidity and its values for the main channel - 4.7 km upstream Stolb
Island (section I in Figure 3) and in the Bykovskaya branch (section II) were practically equal.
Thus in 1969, close to a small water content year, and in 1974, close to a large water content
year, the correlation coefficients of relations of daily water turbidity in June-September for
sections I and II turned out to be practically equal to 1. This indicates that it is appropriate to use
the turbidity values in the main channel for estimating the sediment load discharge in the
Bykovskaya branch. Accordingly, a sufficiently close consistency of the variations of mean
monthly turbidity values at permanent hydrometric sections in the other delta arms with that of
the main channel (section I) can be observed. However, for the Tumatskaya (section IV) and
Olenekskaya (section V) branches in separate cases (July, August 1983 and June 1984) a
multiple excess of monthly turbidity compared to its values at the hydrometric section in the
main channel was observed. The reason for this must be in intensive local erosion of plots
located higher than the above mentioned sections, but lower than section I. In any case, it is
necessary to take into account an approximate character of data on the runoff of suspended
sediment load at the delta sections. This is constantly stressed in the editions of the "Annual
Data on the Regime and Water Quality of the Seas and Marine River Mouths".
In view of the observed consistency between the variations of mean monthly water turbidity
at the hydrometric sections in the Lena delta arms and in its main channel, this feature can be
used for calculating the runoff of suspended sediment load at these sections, based on the actual
turbidity data at the hydrometric section in the main channel - 4.7 km upstream Stolb Island and
data on water discharges at the sections in the arms. The comparison of thus calculated mean
monthly discharges of sediment loads at the sections in the delta arms with the measured
sediment load values over the 1977 to 1993 period has shown the correlation coefficients to be
0.89 to 0.96.
The relations of mean monthly suspended sediment load and water discharges at permanent
hydrometric sections in the Lena delta for June-September are subordinated to the power type
dependencies with correlation coefficients within 0.88-0.92. This allows these dependencies to
be used for approximate estimates of the sediment load discharge at the indicated sections (in
case the observations of both water turbidity and discharges are interrupted), based on the level
data at the gauge of Stolb Island and multiyear curves of water discharges for these sections.
It should be stressed that the presented data characterize the discharge of suspended sediment
load at the head of the Lena delta. They cannot serve as a direct indicator of the amount of
suspended material exported to the sea, especially on a seasonal scale. This problem needs
special research as delta processes are rather complicated.
The level of knowledge of the distribution of water and suspended sediment load discharge in
the river deltas of the East-Siberian Sea Basin is very non-unoform. In terms of full-scale
observations all deltas are poorly studied. Only the Kolyma delta in view of the largest
commercial value was investigated using the entire complex of means: full-scale observations,
hydraulic calculations, physical and numerical modeling. This allowed the estimation of the
typical spatial-temporal features of the distribution of water and sediment load discharge at
different characteristics of the water content and sea regime.
The Kolyma delta begins 3 km downstream the Chersky settlement where the river bifurcates
into two branches - Kamennaya and Chernousovskaya. In 10 km downstream from the
Chersky settlement to the left of Kamennaya there is a cross-branch Markhoyanovskaya which
merging with Chemousovskaya, creates the main left arm - the Pokhodskaya branch (Figure
4). The Kamennaya branch is the main delta arm with sea shipping over its entire length. The
Kamennaya and Pokhodskaya branches are connected by the Poperechnaya I and