RU2039155C1 - Method for intensifying the process of basin gravitation water level control - Google Patents

Abstract

FIELD: hydraulic engineering. SUBSTANCE: method involves digging canals in the longitudinal section of a basin. The canals are made in the form of tubes with impermeable walls and placed between the basin surface and the bottom with their inlets being located in the area potentially floodable with drift flow and outlets being in the area of lowered or practically constant basin gravitation level, the outlet opening being directed to meet the dynamic head of the estuarine river flow. EFFECT: reliable inundation protection; improved water exchange in natural reservoirs. 3 dwg

Description

 The invention relates to hydraulic methods of flood protection, in particular to the protection of the coastline from the effects of drift currents, supporting river mouths.

 Known methods of flood protection, including blocking part of the reservoir with a dam or dam in order to block the path of the drift current, the direction of which usually coincides with the direction of the prevailing wind, and use the fenced area as an accumulator of the river flow, filled during exposure to the same direction of the wind (1 )

Such methods, as shown by the experience of defense of St. Petersburg, have significant disadvantages:
firstly, they are not sufficiently guaranteed against floods due to the fact that when the fenced area is filled, flooding of the coastal strip nevertheless occurs, and even in the fenced part, under the influence of wind and at shallow depths, a drift current arises that raises the water level at the mouth of the river;
secondly, the presence of a dam sharply reduces the natural water exchange at the coastline, which leads to the formation of stagnant zones in the reservoir and a sharp deterioration in the ecological situation.

 There is a method of improving the above methods by intensifying the maintenance of the gravitational level in a reservoir, including the dumping of artificial islands in front of the dam and behind it that form open channels of a certain hydraulic resistance for energy loss by the drift current, as well as an automatically controlled hydraulic unit with flows at the mouth of the flowing river (2).

 This method also does not solve the problem of flood protection, because the open channels themselves do not eliminate the effect of the wind, causing a drift current, and it can even increase due to the small depth of the channels formed between the bulk islands.

 In addition, it does not eliminate, but rather decreases, the natural water exchange inside the reservoir due to the fact that in the artificial delta from the bulk islands some flows will be dominant, while the flow in others will practically stop completely. The ecological situation according to this method can only worsen.

 Closest to the proposed method is a method of intensifying the process of water exchange in a body of water, including making a notch at the bottom of the body of water, the longitudinal axis of which is oriented along the drift current with a prevailing wind, and from the side of the leeward end of the notch, a low-permeable non-flooding structure is placed normal to the longitudinal axis of the notch, what creates local whirlpool areas, partially quenching the drift current and, thereby, lowering the overall level of coastline flooding (3).

 This method involves the creation of recesses in the bottom of the reservoir, which reduces the drift current, especially in comparison with shallow channels according to method (1), under the influence of winds, and the presence of semi-permeable unfilled structures protruding above the mirror of the reservoir from the leeward side further reduces the energy of the drift flow due to the formation and maintenance of vortices near the recesses.

 However, this method is not without drawbacks due to the need to install a significant number of flood-proof structures, worsen their navigational situation in the reservoir and due to the formation of numerous excavations while constantly maintaining their geometric dimensions, counteracting the continuous filling of them with bottom soil, the ecological situation of the reservoir is disturbed and not the economic costs of reproduction of the recesses cease. In addition, an increase in the volume of the reservoir will contribute to a decrease in the rate of river flow through the reservoir, which will also lead to a decrease in the exchange of water in the reservoir and disturbance of the ecological situation.

 The essence of the invention lies in a method of intensifying the process of maintaining the gravitational level of a reservoir, including establishing a preliminary connection between the wind rose and the parameters of the drift wind flow in the period between ice formation and the implementation of channels in the form of pipes with impermeable walls, which are located between the reservoir mirror and the bottom, the inlets in the zone potential flooding by the drift current, and by the weekend in the zone of low or almost constant gravitational level of the reservoir. Inlet openings of the channels are arranged towards the dynamic pressure of the river mouth flow. This organizes the outflow of water directly from the zone of a high level to a zone of a low, or at least a zone of a constant level, which is maintained even in the presence of a drift current, the gravitational level characteristic of a calm state of a water body, through channels isolated from the drift flow of the liquid and causing this flow (flow ) reasons, in particular wind.

 The fluid flow is carried out either under the influence of a gravitational pressure drop at the ends of the channel, one of which is in the area of flooded banks, and the other in the zone of normal (with no wind) or low gravity level, or under the influence of flow drivers, for example, axial superchargers. Moreover, the channels do not have to be located along drift currents. The natural flow through the channels is ensured both by wind energy raising the liquid level in the reservoir (relative to gravitational) at one of the channel end openings and lowering (or leaving the gravitational constant) at the other channel end opening, as well as due to the hydrodynamic wellhead pressure flowing into the water body rivers where they are available. The most effective is the use of channels at the same time as the pressure from the drift current, and the dynamic pressure flowing into the water body of the river. The design of the channels should provide isolation of the flow in them from the effects of fluid flows, both water and atmospheric. They can be made, for example, in the form of pipes of large diameter round or another rational section. The material and its thickness should provide durability, environmental compatibility and sufficient rigidity to exclude the influence of external mechanical disturbances on the flow inside the channel. The location of the channels in the reservoir is due to the fact that the flow in them should not be located above the level of the mirror of the reservoir with its various (possible) fluctuations. The same requirements apply to channel openings.

 Thus, the wind energy that causes drift current and flooding of the coast is used to create a water cycle in the reservoir from the flooding zone to the zone of low gravity level through channels and back along the drift current to the flooding zone, which significantly intensifies water exchange and, as a result, improves the environmental situation reservoir in general. At the same time, through the channels with a speed significantly exceeding the speed in the open space of the reservoir, and this speed will be the greater, the greater the level difference at the ends of the channel, the liquid will flow from the flooding zone to the lower level zones, which will ensure automatic reliable protection against floods due to overflow of flooding water through channels. In addition, water (liquid) flowing from the end hole to the bottom region of the lower level will have a speed directed in the opposite direction to the wind and the drift flow caused by it, which will significantly complicate the return of such a flow to the drift flow and, thereby, reduce the degree of flooding coastline as a whole.

 In FIG. 1 shows a pond, top view; in FIG. 2 is a front view of a reservoir dissected by a vertical plane located along the direction of the drift current (front section); in FIG. 3 is a left view of a reservoir dissected by a vertical plane perpendicular to the direction of the drift current (lateral section).

 In FIG. 1 is a schematic representation of a body of water 1, a coastline 2 and a river 3, wherein zone 4 subject to flooding is represented by a dashed line. In FIG. Figure 2 shows the section of the reservoir 1 and part of the river 3, the solid line indicates the gravitational level 5 of the reservoir 1, and the dashed maximum possible level 6 of the banks of the reservoir 1 and river 3 due to the backwater of the estuary runoff.

 Three channels 7 are placed between the mirror of the reservoir 1 and its bottom and are made in the form of continuous pipes with walls and openings that are impervious to mechanical stress, and the inlet openings located closer to the banks of the channels 7, in FIG. 2 are located in the bottom region of the zone of reduced gravitational level 8. The channels 7 themselves are laid along the bottom of the reservoir 1. The arrows indicate the movement of the wind, drift current and current in the channels 7. In FIG. 3 shows the possible sections of the channels: round, rectangular, oval.

 The method is as follows.

 Due to the flow of water from the mouth of the river 3 to the reservoir 1, the flooded shore 4 will have a water level slightly higher than gravity. A weak dynamic pressure is added to this, and all together will provide a small movement of fluid in the channels 7 away from the potentially flooded shore 4, and the speed of water in the channels 7 will be significantly higher than in the whole body of water 1 due to the lack of forces opposing the return of water in open reservoir 1, and, thereby, intensification of water exchange in reservoir 1 will be carried out by transferring water from coastal zone 4 to zone 8, far from it, and organization in the last powerful source. When the wind appears (see Fig.), A satellite-like drift current arises, which increases the water level near the shore 4 and lowers it in other parts of the reservoir 1. This leads to an increase in the difference in geometric pressure at the ends of channels 7, strengthens the flow in them, approximately proportionally. Water from the flooding zone intensively enters the zone of low gravity level from reservoir 1, thereby reducing the volume of water in zone 4 and intensifying water exchange in the entire reservoir, improving its ecology. With the passage of "long waves", comparable in length with channels 7, the water exchange between the remote zones 4 and 8 of the reservoir 1 will also improve.

 More specific development of the device that implements the proposed method is possible when identifying specific parameters of the reservoir 1. So, if the overflow through channels 7 in the opposite direction is unacceptable, i.e. into zone 4 (opposite the direction of the arrows), then, for example, the outlet openings in the channels 7 should be equipped with automatic shutters (not shown in Fig.), which exclude the reverse flow through the channels 7.

Claims (1)

 METHOD OF INTENSIFICATION OF THE PROCESS OF MAINTAINING THE GRAVITATIONAL LEVEL OF THE RESERVOIR, including the establishment of a preliminary connection between the wind rose and the parameters of the drift wind flow in the period between ice formation and the implementation of channels in the longitudinal section of the reservoir, characterized in that the channels are made in the form of pipes with impermeable walls and are placed the bottom in the cross section, the inlets in the zone of potential flooding by the drift current, and the outlet in the zone of the cross section of the reservoir, corresponds to the zone of the reduced or almost constant gravitational level of the reservoir, while the inlet openings of the channel or channels located in the middle part of the longitudinal section of the reservoir, are located towards the dynamic pressure of the wellhead stream of the reservoir.

Images