210
A. Sh. Khabidov
It seems likely that the relief-forming and depositional sedimentary environments,
revealed at the Novosibirsk reservoir, are common types of environment for man-made
lakes of plain areas with similar features. Small differences in hydrodynamics, the
configuration of the basin, the original relief and geological structure between one lake
and another may simplify or complicate the scheme presented. Nevertheless such
changes do not cause serious repercussions. Furthermore, based on the data provided
by the studies of Reineck and Singh (1973), Matarzin et al. (1977), Allen and
Collinson (1990) and others, a large body of remote sensing data, and field surveys,
Khabidov et al. (1998) suggested that certain environments are present within the
basins of piedmont man-made lakes as well.
LITTORAL AND SHORELINE PROCESSES WITHIN MAIN ENVIRONMENTS
At the entrance section of Novosibirsk Reservoir, annual normal sediment flux ranges
up to
per year. The major part of the sediment, mainly sand, is deposited
over the fluvial-dominated area, because of the low wave energy of the lake basin. The
erosion is most often observed in the channels and at the terrestrial patches adjacent to
them, with the total erosion rate not more than
per year (Lysenko, 1967).
This being so, within the fluvial-dominated environment of the lake numerous
aggradative isles, operating, cut-off and overgrown river channels separated by drained
or semi-drained terrestrial patches as well as shallow subenvironments (depths of less
than 2.5-3 m) with quiet or even stagnant state are typical features. The latter ones are
most often presented by a diversity of complex bays, river plains, small lakes, and
swamps.
The front of the delta-like area is marked by geomorphic changes and the
distinct replacement of coarse deposits by fine-grained ones on the bed; as this takes
place, it is more advanced in the dam direction of the righthand side of the coast of the
man-made lake. The shallow sub-environments of the lake basin are completely
substituted for deeper environments downward from the front.
The geomorphic changes are most pronounced in coastal morphology and
dynamics. The shoreline of the transition zone of Novosibirsk Reservoir presents the
continuous lines of cliffs or steep slopes caused by erosion. Typically, a sandy beach
with a narrow berm (not more than 1.5-2 m) is adjacent to an escarpment. The bottom
at the nearshore zone has a slope from 2 –3° up to 6-8°. At the sedimentary shores, the
modern erosion rate reaches maximum (3-5 m/yr) in circumstances where waves
interact with channel flows.
Here, the longshore sediment transport due to combined channel flows and
wave-induced currents is dominant in the nearshore zone. However, judging from the
replacement of combined current and wave ripples by wave ripples (Khabidov et al.,
1998), the role of channel flows is progressively decreasing outward from the front of
delta-like area and, in contrast, the role of wave-induced currents is increasing. The
cross-shore sediment transport rate increases concurrently because of the undertow
occurrence. As a consequence different accretive landforms at the windward side of
natural and artificial coastal barriers are common within this area. Again, bay-mouth
A. Sh. Khabidov
It seems likely that the relief-forming and depositional sedimentary environments,
revealed at the Novosibirsk reservoir, are common types of environment for man-made
lakes of plain areas with similar features. Small differences in hydrodynamics, the
configuration of the basin, the original relief and geological structure between one lake
and another may simplify or complicate the scheme presented. Nevertheless such
changes do not cause serious repercussions. Furthermore, based on the data provided
by the studies of Reineck and Singh (1973), Matarzin et al. (1977), Allen and
Collinson (1990) and others, a large body of remote sensing data, and field surveys,
Khabidov et al. (1998) suggested that certain environments are present within the
basins of piedmont man-made lakes as well.
LITTORAL AND SHORELINE PROCESSES WITHIN MAIN ENVIRONMENTS
At the entrance section of Novosibirsk Reservoir, annual normal sediment flux ranges
up to
per year. The major part of the sediment, mainly sand, is deposited
over the fluvial-dominated area, because of the low wave energy of the lake basin. The
erosion is most often observed in the channels and at the terrestrial patches adjacent to
them, with the total erosion rate not more than
per year (Lysenko, 1967).
This being so, within the fluvial-dominated environment of the lake numerous
aggradative isles, operating, cut-off and overgrown river channels separated by drained
or semi-drained terrestrial patches as well as shallow subenvironments (depths of less
than 2.5-3 m) with quiet or even stagnant state are typical features. The latter ones are
most often presented by a diversity of complex bays, river plains, small lakes, and
swamps.
The front of the delta-like area is marked by geomorphic changes and the
distinct replacement of coarse deposits by fine-grained ones on the bed; as this takes
place, it is more advanced in the dam direction of the righthand side of the coast of the
man-made lake. The shallow sub-environments of the lake basin are completely
substituted for deeper environments downward from the front.
The geomorphic changes are most pronounced in coastal morphology and
dynamics. The shoreline of the transition zone of Novosibirsk Reservoir presents the
continuous lines of cliffs or steep slopes caused by erosion. Typically, a sandy beach
with a narrow berm (not more than 1.5-2 m) is adjacent to an escarpment. The bottom
at the nearshore zone has a slope from 2 –3° up to 6-8°. At the sedimentary shores, the
modern erosion rate reaches maximum (3-5 m/yr) in circumstances where waves
interact with channel flows.
Here, the longshore sediment transport due to combined channel flows and
wave-induced currents is dominant in the nearshore zone. However, judging from the
replacement of combined current and wave ripples by wave ripples (Khabidov et al.,
1998), the role of channel flows is progressively decreasing outward from the front of
delta-like area and, in contrast, the role of wave-induced currents is increasing. The
cross-shore sediment transport rate increases concurrently because of the undertow
occurrence. As a consequence different accretive landforms at the windward side of
natural and artificial coastal barriers are common within this area. Again, bay-mouth