Littoral and Shoreline Processes in Large Man-Made Lakes
207
reservoirs. The relation between them may range from 8% to 20% under the seasonal
and from 20% to 50% under the long-term control, respectively, exclusive of the
tropical and equatorial areas (Voropaev and Vendrov, 1979). The water level
fluctuations vary in amplitude as the relation. Besides, it changes along a man-made
lake fetch: the magnitude of fluctuations reaches a maximum value at the vicinity of
dam and is negligible at the junction of a river and reservoir.
Wind and waves are further important factors affecting the depositional
sedimentary environment of man-made lakes. This effect arises by virtue of the fact
that during the reservoir filling, as its water level rises, the lake fetch length, area, and
mean depth increase. Clearly the wave climate of a man-made lake is associated not
only with the frequency of winds and their velocities, but with the morphology of the
lake basin and the water fluctuation pattern as well. For these reasons, the wave height,
all other factors being equal, increases away from the junction of river and reservoir at
all instances.
It seems reasonable to say that, taken together, the factors outlined above are
responsible for differentiating amongst depositional sedimentary environments of manmade lake basins. Let us consider this as in interplay between geomorphic, geological
and physical factors by the example of Novosibirsk Reservoir. This man-made lake is
well suited for the explanation of such mutual relations, because of the isolated
location, simple plane shape, classical morphology of the basin, and uniform
composition of sedimentary coasts.
THE PATTERN OF PHYSICAL PROCESSES IN MAN-MADE LAKE
The Novosibirsk Reservoir was formed in 1956-1959 in Western Siberia, Russia when
the Ob River was dammed ca. 20 km upstream from the city of Novosibirsk (the dam:
latitude 55°N, longitude 83°E). The man-made lake reaches 220 km southwest and has
the following morphometrical features: maximum, mean, and minimal widths are 22,
10, and 2 km, respectively, maximum and mean depths are 25 and 9 m, respectively,
water surface area is
total and effective water storage are
and
respectively, and total shoreline length is 550 km.
The lake's basin inherited main features of morphology and geology of the Ob
River valley. The valley had a simple plane shape and an asymmetric shape in section,
That is why the deepest area of the man-made lake basin is shifted towards the right
shore. The river plain and three terraces of sand and sandy loam origin were presented
in the original relief (Beirom and Shirokov, 1968).
Seasonal changes in the water level of the Novosibirsk Reservoir include: (i)
qater level rise with duration ca. 50 days at a rate of ca. 0.1 m per day, (ii) the level of
stabilization at the project mark of high water (mean duration ca. 120 days), and (iii)
water level subsidence with duration ca. 195 days at a rate of ca. 0.02 m per day. The
fluctuations of ca. 5 m per year at a distance of 135-140 km from the dam remain
practically the same and then a gradual decrease is observed; as this takes place, wide
fluctuations are fixed now and then. Notice that effective water storage of Novosibirsk
Reservoir
is well below the Ob River discharge (more than
per year),
207
reservoirs. The relation between them may range from 8% to 20% under the seasonal
and from 20% to 50% under the long-term control, respectively, exclusive of the
tropical and equatorial areas (Voropaev and Vendrov, 1979). The water level
fluctuations vary in amplitude as the relation. Besides, it changes along a man-made
lake fetch: the magnitude of fluctuations reaches a maximum value at the vicinity of
dam and is negligible at the junction of a river and reservoir.
Wind and waves are further important factors affecting the depositional
sedimentary environment of man-made lakes. This effect arises by virtue of the fact
that during the reservoir filling, as its water level rises, the lake fetch length, area, and
mean depth increase. Clearly the wave climate of a man-made lake is associated not
only with the frequency of winds and their velocities, but with the morphology of the
lake basin and the water fluctuation pattern as well. For these reasons, the wave height,
all other factors being equal, increases away from the junction of river and reservoir at
all instances.
It seems reasonable to say that, taken together, the factors outlined above are
responsible for differentiating amongst depositional sedimentary environments of manmade lake basins. Let us consider this as in interplay between geomorphic, geological
and physical factors by the example of Novosibirsk Reservoir. This man-made lake is
well suited for the explanation of such mutual relations, because of the isolated
location, simple plane shape, classical morphology of the basin, and uniform
composition of sedimentary coasts.
THE PATTERN OF PHYSICAL PROCESSES IN MAN-MADE LAKE
The Novosibirsk Reservoir was formed in 1956-1959 in Western Siberia, Russia when
the Ob River was dammed ca. 20 km upstream from the city of Novosibirsk (the dam:
latitude 55°N, longitude 83°E). The man-made lake reaches 220 km southwest and has
the following morphometrical features: maximum, mean, and minimal widths are 22,
10, and 2 km, respectively, maximum and mean depths are 25 and 9 m, respectively,
water surface area is
total and effective water storage are
and
respectively, and total shoreline length is 550 km.
The lake's basin inherited main features of morphology and geology of the Ob
River valley. The valley had a simple plane shape and an asymmetric shape in section,
That is why the deepest area of the man-made lake basin is shifted towards the right
shore. The river plain and three terraces of sand and sandy loam origin were presented
in the original relief (Beirom and Shirokov, 1968).
Seasonal changes in the water level of the Novosibirsk Reservoir include: (i)
qater level rise with duration ca. 50 days at a rate of ca. 0.1 m per day, (ii) the level of
stabilization at the project mark of high water (mean duration ca. 120 days), and (iii)
water level subsidence with duration ca. 195 days at a rate of ca. 0.02 m per day. The
fluctuations of ca. 5 m per year at a distance of 135-140 km from the dam remain
practically the same and then a gradual decrease is observed; as this takes place, wide
fluctuations are fixed now and then. Notice that effective water storage of Novosibirsk
Reservoir
is well below the Ob River discharge (more than
per year),