CN114657933A - Yellow river middle and downstream continuous water diversion dredging site based on vegetation and curve and yellow river dredging method - Google Patents
Yellow river middle and downstream continuous water diversion dredging site based on vegetation and curve and yellow river dredging method Download PDFInfo
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- CN114657933A CN114657933A CN202210444933.4A CN202210444933A CN114657933A CN 114657933 A CN114657933 A CN 114657933A CN 202210444933 A CN202210444933 A CN 202210444933A CN 114657933 A CN114657933 A CN 114657933A
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02B—HYDRAULIC ENGINEERING
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- A01G—HORTICULTURE; CULTIVATION OF VEGETABLES, FLOWERS, RICE, FRUIT, VINES, HOPS OR SEAWEED; FORESTRY; WATERING
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- A01G—HORTICULTURE; CULTIVATION OF VEGETABLES, FLOWERS, RICE, FRUIT, VINES, HOPS OR SEAWEED; FORESTRY; WATERING
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- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
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- E02B3/02—Stream regulation, e.g. breaking up subaqueous rock, cleaning the beds of waterways, directing the water flow
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Abstract
The invention discloses a vegetation and bend-based continuous water diversion and dredging site for the middle and lower reaches of a yellow river, which comprises a U-shaped water diversion and dredging area, wherein an arc-shaped section of the water diversion and dredging area forms a second dredging area, and the water diversion and dredging areas on two sides of the second dredging area are a first dredging area and a third dredging area respectively; the end parts of the first dredging area and the third dredging area are communicated with the yellow river, and a diversion gate is arranged at the communication part of the first dredging area and the yellow river; submerged vegetation groups for intercepting coarse sand are planted in the first dredging area, the vegetation height of the submerged vegetation groups is less than or equal to MAX centimeters, and the average water depth of the first dredging area is greater than or equal to 2MAX centimeters; emergent aquatic vegetation groups are planted in the second silt discharging area. The invention is based on vegetation and curve yellow river middle and lower reaches and draws water and desilting the place continuously, adopt different desilting areas and different settlement tactics to fine sand and coarse sand separately, to realize not only improving and subsiding the efficiency, but also not increasing the purpose of the water resistance too much as possible, can realize and draw the silt continuously, needn't open and close the gate repeatedly.
Description
Technical Field
The invention relates to the technical field of river silt control.
Background
The yellow river is the river with the largest sand content in the world, the high sediment content causes serious sedimentation of rivers and reservoirs at the middle and lower reaches of the yellow river, and partial river reach forms an overground suspension river, thus causing great harm.
The dredging is an engineering measure for reducing the content of the downstream silt in the yellow river, and is also the 'discharging' in 'blocking, discharging, adjusting and digging' in the yellow river silt treatment strategy.
The desilting means that the yellow river water with high sand content is introduced into the beach land, so that the carried silt is deposited at a designated position (desilting site), and then the clear water is introduced back to the yellow river, thereby reducing the silt content in the main river channel of the yellow river.
Traditional desilting place is exactly a slice of empty lot, introduces the desilting place with water after, need close the gate and stew, treats that silt subsides the back, emits water again. The traditional desilting method has the following defects: firstly, the continuous operation cannot be carried out, and water cannot be introduced for dredging when the gate is closed and the gate is kept still; secondly, the standing still consumes a long time, and the two points seriously influence the dredging efficiency; and finally, a dredging period is formed from the opening of the gate to the standing and then to the next opening of the gate to the dredging, each dredging period needs to be opened and the dredging is performed and the gate is closed and stands, the gate operation needs to be continuously performed, and the labor cost and the labor intensity are improved.
Disclosure of Invention
The invention aims to provide a vegetation and bend based continuous water diversion and dredging site in the middle and lower reaches of a yellow river to realize continuous dredging operation aiming at the defects of the prior art.
In order to achieve the aim, the invention discloses a yellow river middle and lower reaches continuous water diversion and silt discharge field based on vegetation and bend, which comprises a U-shaped water diversion and silt discharge area,
the U shape comprises two side edges and an arc section connecting the two side edges, the arc section of the water diversion dredging area forms a second dredging area, and the water diversion dredging area on the two sides of the second dredging area is a first dredging area and a third dredging area respectively; the gradient of the riverbed of the water diversion and silt removal area along the water flow direction is called as the flow direction gradient;
the first desilting area is used for blocking and settling coarse sand, the second desilting area is used for blocking and settling fine sand, and the third desilting area is used for guiding water back to the yellow river;
the end parts of the first desilting area and the third desilting area are communicated with the yellow river, the flowing direction of water is taken as the downstream direction, and the first desilting area to the third desilting area are sequentially arranged from the upstream direction to the downstream direction; a diversion gate is arranged at the position where the first desilting area is communicated with the yellow river, and a water pump for pumping water into the first desilting area is arranged at the diversion gate;
submerged vegetation groups for intercepting coarse sand are planted in the first silt discharging area, the vegetation height of the submerged vegetation groups is less than or equal to MAX cm, the average water depth of the first silt discharging area is greater than or equal to 2MAX cm, water flow at the submerged vegetation groups is a high-obstruction area of the first silt discharging area, and a water flow area above the submerged vegetation groups forms a low-flow-resistance area of the first silt discharging area; emergent aquatic vegetation groups are planted in the second silt discharging area;
the flow direction gradient from the first desilting area to the third desilting area is increased in sequence; the lengths of the first desilting area, the second desilting area and the third desilting area are all more than or equal to 4 kilometers.
The vegetation height of the submerged vegetation group is less than or equal to 50 cm; the average water depth of the first desilting area is more than or equal to 100 cm; the planting density of the submerged vegetation group is 28-32 plants per square meter;
the vegetation height of the emergent aquatic vegetation group is more than 1.5 meters, the top end of the emergent aquatic vegetation group is higher than the water surface, and the planting density is 15-17 plants per square meter.
The second silt discharging area is an arc-shaped section, and the riverbed at the radial outer side of the arc-shaped section is lower than the riverbed at the radial inner side.
At the joint of the first dredging area and the second dredging area, the river bed of the second dredging area is at least 0.5 m higher than that of the first dredging area; and at the joint of the second desilting area and the third desilting area, the river bed of the third desilting area is at least 0.3 m higher than that of the second desilting area.
The submerged vegetation group is formed by planting one or more of curly pondweed, leek grass, bermuda grass, citronella or suaeda salsa:
the emergent aquatic vegetation group is formed by planting one or more of reed, cattail or rhizoma alismatis;
emergent aquatic vegetation groups are planted at the middle rear part of the upstream direction and the downstream direction of the second silt discharging area.
The flexural modulus of elasticity E of the vegetation is expressed as:
wherein F is the transverse load borne by the plant, L is the length of the plant, I is the moment of inertia of the plant, and u is the offset distance of the vegetation end point when impacted by water flow;
the moment of inertia I of the plant is:
(ii) a Wherein d is the diameter of the plant stem;
for submerged vegetation in the first desilting area, E is more than 1;
and E is less than 0.1 for emergent aquatic vegetation in the second silt discharging area.
The radius of the arc of the second desilting area is more than or equal to 0.8 kilometer and less than or equal to 1.6 kilometers.
The invention also discloses a yellow river desilting method which is carried out by adopting the yellow river middle and lower reaches continuous water diversion desilting field based on the vegetation and the curve, the water diversion gate is kept in an open state, the water pump is opened to pump water into the first desilting area, when water flow passes through the first desilting area, coarse sand in the water enters the high barrier area under the action of gravity and is deposited on the riverbed of the first desilting area under the action of submerged vegetation groups; the low flow resistance area of the first silt discharging area enables water flow to smoothly enter the second silt discharging area;
in the process that water flows in the first half section of the second desilting area, fine sand in the water body is concentrated to the outer side of the second desilting area under the action of centrifugal force, and the concentrated fine sand can be more effectively settled; when the water flow passes through the emergent aquatic vegetation group of the second desilting area, the fine sand in the water is blocked by the emergent aquatic vegetation group and sinks to the riverbed of the second desilting area under the action of gravity;
after the water flow enters the third desilting area, the third desilting area has the largest flow direction gradient in the three areas, so the water flow quickly flows back to the yellow river.
The invention has the following advantages:
the water flow just introduced from the yellow river has a large sand content, coarse sand generally gathers at the bottom of the water flow, and when the coarse sand is serious, a density flow (the upper part is the water flow, and the lower part is the sand flow) can be formed. The fine sand is distributed on all parts of the water flow more uniformly and can not be gathered at the bottom of the water flow in large quantity, so that different desilting areas and different sedimentation strategies are respectively adopted for the fine sand and the coarse sand, and the purposes of improving sedimentation efficiency and not increasing water flow resistance as much as possible are achieved.
The coarse sand settles in the first desilting zone.
If the height of the vegetation is too high, the resistance to the water flow is significantly increased, affecting the efficiency of the water flow. In the first desilting area, the flow direction gradient is the smallest in the three areas, and the water flow is the slowest, so that the sedimentation of coarse sand is facilitated. The average water depth of the first silt discharging area is more than or equal to 2MAX centimeters, so that a sufficiently high low flow resistance area is arranged above the vegetation group of the first silt discharging area, water can flow forward to the second silt discharging area under the condition of overall low resistance, and the first silt discharging area forms up-and-down slow water flow (the flow rate of the low flow resistance area is higher than that of the high blocking area on the lower layer). The coarse sand is blocked by the dense vegetation group in the first desilting area and subsides.
The fine sand settles in the second desilting zone.
Emergent aquatic vegetation groups are the first technical means for promoting fine sand sedimentation and siltation. The emergent aquatic vegetation swings along with the water flow, and the top of the emergent aquatic vegetation discharges water, so that the emergent aquatic vegetation can well block the suspended sand in water.
The arc-shaped section bend is a second technical means for promoting fine sand sedimentation, when water flows through the bend, silt in water is thrown to the outer side of the bend and is concentrated under the action of centrifugal force, the concentrated fine sand is easier to settle than dispersed fine sand, and the settling speed is higher.
Under the dual action of the emergent aquatic vegetation group and the centrifugal force to promote the fine sand to be concentrated on the outer side of the curve, the fine sand can be quickly and effectively settled in the second desilting area.
According to the vegetation group of the first silt discharging area, the first silt discharging area is divided into the low flow resistance area and the high blocking area from top to bottom, so that the whole flow resistance of the first silt discharging area is small, coarse sand is effectively blocked, a foundation is provided for continuous water diversion and silt discharging, and the small whole flow resistance is beneficial to reducing the power of a water pump.
The flow direction slope in first desilting district to third desilting district increases in proper order to form the situation that first desilting district rivers are slowest and are favorable to the coarse sand to subside, and third desilting district rivers are the most urgent and are favorable to the rivers backward flow to go into the yellow river.
After long-term use, the riverbed is lifted to a certain degree by the deposited silt, and the riverbed needs to be dug to be cleaned. In the second desilting area, fine sand is more settled on the radial outer side due to the action of centrifugal force, so that the riverbed on the radial outer side is lower than the riverbed on the radial inner side, the reservoir capacity can be effectively improved, the integral silt containing capacity is improved, and the dredging and cleaning frequency is reduced.
Because a large amount of coarse sand is deposited in the first desilting area and a large amount of fine sand is deposited in the second desilting area, the first desilting area is larger than the second desilting area and the second desilting area is larger than the third desilting area according to the sediment amount of the silt.
The silt deposit amount of the silt is large, the riverbed of the silt deposit area is lower, so that the whole reservoir capacity is improved, the phenomenon that the riverbed of the first silt deposit area is lifted to be higher than that of the second silt deposit area and the riverbed of the second silt deposit area is lifted to be higher than that of the third silt deposit area due to different deposit amounts of the areas can not be immediately generated in use, and the frequency of dredging and cleaning the riverbed caused by the lifting of the riverbed is reduced.
The submerged plants such as curly pondweed, Leersia hexandra Swartz, Cynodon dactylon, citronella and Suaeda glauca have the characteristics of high rigidity, low height, luxuriant branches and leaves and the like, and can block off the bed-pushed substances (coarse sand) near the riverbed.
The reed, the cattail, the alisma orientale and other specific emergent aquatic plants have the characteristics of high flexibility and high height, and can swing along with water flow and extend upwards out of the water surface, so that the aim of blocking suspended sand in water is fulfilled.
The emergent aquatic vegetation group is planted at the middle rear part of the upstream direction and the downstream direction of the second silt discharging area, so that the water flow is not influenced by the emergent aquatic vegetation group when passing through the front half section of the second silt discharging area, more silt is focused to the outer side of the silt discharging area (arc section) under the action of centrifugal force, and the silt is more favorable for sedimentation after being concentrated in the water body; and the second desilting district is owing to first half section (the half section that is close to first desilting district) do not plant emergent aquatic vegetation, therefore the whole flow resistance in second desilting district is littleer, is favorable to reducing water pump power.
The submerged vegetation E in the first silt discharging area 1 is more than 1, so that the submerged vegetation has proper rigidity to block bed load (coarse sand) near a riverbed, and the submerged vegetation is prevented from being bent due to the fact that the submerged vegetation cannot bear the thrust of the bed load, and further the effect of blocking the coarse sand is greatly reduced. Emergent aquatic vegetation E in the second silt discharging area 2 is less than 0.1, so that the emergent aquatic vegetation has proper rigidity to swing along with water flow. The value of the E value is convenient for selecting proper submerged vegetation and emergent vegetation from various plants.
If the radius of the curve of the second desilting area is too large, the centrifugal action is too weak, and the effect of throwing the silt to the outer side for sedimentation cannot be achieved obviously. If the radius of the curve of the second dredging area is too small, the effect of sudden turning appears, so that the flow resistance is greatly increased, and the dredging efficiency is reduced. In order to realize better dredging effect, the applicant firstly proposes a target of considering both centrifugal effect and water body flow resistance, under the guidance of the target, through calculation and experiments, the most appropriate curve radius of 0.8-1.6 kilometers is determined, and the curve radius of the second dredging area is the best 1.2 kilometers.
Drawings
FIG. 1 is a plan layout view of a yellow river middle and downstream continuous water diversion and silt discharge field based on vegetation and curves;
FIG. 2 is a schematic longitudinal sectional structure from the first desilting area to the third desilting area; the purpose of figure 2 is to express the step formed by the step difference between adjacent dredging areas.
Detailed Description
As shown in fig. 1 and 2, the continuous water diversion and desilting site suitable for the middle and lower reaches of the yellow river 11 comprises a U-shaped water diversion and desilting area, the U-shaped water diversion and desilting area comprises two side sections and an arc section connecting the two side sections, the arc section of the water diversion and desilting area forms a second desilting area 2, and the water diversion and desilting areas on the two sides of the second desilting area 2 are a first desilting area 1 and a third desilting area 3 respectively; the gradient of the riverbed of the water diversion and silt removal area along the water flow direction is called as the flow direction gradient;
the first desilting area 1 is used for blocking and settling coarse sand, the second desilting area 2 is used for blocking and settling fine sand, and the third desilting area 3 is used for guiding water back to the yellow river 11;
the end parts of the first silt discharging area 1 and the third silt discharging area 3 are communicated with a yellow river 11, the flowing direction of water is taken as a downstream direction, and the first silt discharging area 1 to the third silt discharging area 3 are sequentially arranged along the direction from the upstream to the downstream; a diversion gate 4 is arranged at the communication part of the first desilting area 1 and the yellow river 11, and a water pump for pumping water into the first desilting area 1 from the yellow river 11 is arranged at the diversion gate 4; the water pump is conventional and not shown.
the flow direction gradient of the first desilting area 1 to the third desilting area 3 is increased in sequence; the lengths of the first desilting area 1, the second desilting area 2 and the third desilting area 3 are all more than or equal to 4 kilometers (preferably 5 kilometers).
The water stream just introduced from the yellow river 11 has a high sand content, and coarse sand generally accumulates at the bottom of the water stream, and when the sand is severe, a heavy stream (the upper part is the water stream and the lower part is the sand stream) can be formed. The fine sand is distributed on all parts of the water flow more uniformly and can not be gathered at the bottom of the water flow in large quantity, so that different desilting areas and different sedimentation strategies are respectively adopted for the fine sand and the coarse sand, and the purposes of improving sedimentation efficiency and not increasing water flow resistance as much as possible are achieved.
The coarse sand settles in the first dredging zone 1.
If the height of the vegetation is too high, the resistance to the water flow is significantly increased, affecting the efficiency of the water flow. In the first desilting area 1, the flow direction gradient is the smallest among three areas, and the water flow is the slowest, so that the sedimentation of coarse sand is facilitated. The average water depth of the first silt discharging area 1 is more than or equal to 2MAX centimeters, so that a sufficiently high low flow resistance area 7 is arranged above the vegetation group of the first silt discharging area 1, water can flow forward to the second silt discharging area 2 under the overall low resistance condition, and water flow which is fast and slow up and down is formed in the first silt discharging area 1 (the flow speed of the low flow resistance area 7 is faster than that of the high resistance area 6 at the lower layer). The coarse sand is stopped by the dense vegetation group of the first desilting area 1 and subsides.
The fine sand settles in the second dredging zone 2.
The emergent aquatic vegetation group 8 is the first technical means for promoting fine sand sedimentation and siltation. The emergent aquatic vegetation swings along with the water flow, and the top of the emergent aquatic vegetation discharges water, so that the emergent aquatic vegetation can well block the suspended sand in water.
The arc-shaped section bend is a second technical means for promoting fine sand sedimentation, when water flows through the bend, silt in water is thrown to the outer side of the bend and is concentrated under the action of centrifugal force, the concentrated fine sand is easier to settle than dispersed fine sand, and the settling speed is higher.
Under the dual action of the emergent aquatic vegetation group 8 and centrifugal force to promote the fine sand to be concentrated on the outer side of the curve, the fine sand can be rapidly and effectively settled in the second silt region 2.
According to the invention, the vegetation group of the first silt discharging area 1 divides the first silt discharging area 1 into the low flow resistance area 7 and the high resistance area 6 from top to bottom, so that the whole flow resistance of the first silt discharging area 1 is small, coarse sand is effectively intercepted, a foundation is provided for continuous water diversion and silt discharging, and the small whole flow resistance is beneficial to reducing the power of a water pump.
The flow direction slope in first desilting district 1 to third desilting district 3 increases in proper order to form the situation that 1 rivers of first desilting district are the slowest and are favorable to the coarse sand to subside, and 3 rivers of third desilting district are the most urgent and are favorable to the water reflux to go into yellow river 11.
The vegetation height of the submerged vegetation group 5 is less than or equal to 50 cm (MAX =50 cm); the average water depth of the first desilting area 1 is more than or equal to 100 centimeters (2MAX is 100 centimeters); the planting density of the submerged vegetation group 5 is 28-32 plants (including two ends, preferably 30 plants) per square meter;
the vegetation height of the emergent aquatic vegetation group 8 is more than 1.5 meters, the top end of the emergent aquatic vegetation group is higher than the water surface, and the planting density is 15-17 plants (including two ends, preferably 16 plants) per square meter. The emergent aquatic vegetation group 8 has low planting density, and has small influence on water flow resistance while ensuring the sand blocking effect.
The second silt discharging area 2 is an arc-shaped section, and the riverbed at the radial outer side of the arc-shaped section is lower than the riverbed at the radial inner side. After long-term use, the riverbed is lifted to a certain degree by the deposited silt, and the riverbed needs to be dug to be cleaned. In the second desilting area 2, fine sand is more settled on the radial outer side due to the action of centrifugal force, so that the riverbed on the radial outer side is lower than the riverbed on the radial inner side, the reservoir capacity can be effectively improved, the integral silt containing capacity is improved, and the dredging and cleaning frequency is reduced. As shown in fig. 1, the height of the bed at the point a is lower than the height of the bed at the point B, and the bed at the point a is preferably lower than the bed at the point B by a value of 1 meter.
At the joint of the first silt removing area 1 and the second silt removing area 2, the river bed of the second silt removing area 2 is at least 0.5 meter higher than that of the first silt removing area 1 so as to form a first step 9; at the junction of the second dredging area 2 and the third dredging area 3, the bed of the third dredging area 3 is at least 0.3 m higher than the bed of the second dredging area 2 to form a second step 10.
Because a large amount of coarse sand is deposited in the first desilting area 1 and a large amount of fine sand is deposited in the second desilting area 2, the first desilting area 1 is larger than the second desilting area 2 and the second desilting area 2 is larger than the third desilting area 3 according to the sediment amount of the silt.
The silt deposit amount of the silt is large, the riverbed of the silt deposit area is lower, so that the whole storage capacity is improved, the phenomenon that the riverbed of the first silt deposit area 1 is lifted to be higher than the riverbed of the second silt deposit area 2 and the riverbed of the second silt deposit area 2 is lifted to be higher than the riverbed of the third silt deposit area 3 due to different sediment amounts of all areas can not be immediately generated in use, and the frequency of dredging and cleaning the riverbed caused by lifting the riverbed is reduced.
Specifically, the submerged vegetation group 5 is planted with one or more of curly pondweed, curly bluegrass, bermuda grass, citronella or suaeda salsa:
the emergent aquatic vegetation group 8 is planted by one or more of reed, cattail or rhizoma alismatis; emergent aquatic vegetation groups 8 are planted at the middle rear part of the upstream and downstream directions of the second silt discharging area 2.
The submerged plants such as curly pondweed, Leersia hexandra Swartz, Cynodon dactylon, citronella and Suaeda glauca have the characteristics of high rigidity, low height, luxuriant branches and leaves and the like, and can block off the bed-pushed substances (coarse sand) near the riverbed.
The reed, the cattail, the alisma orientale and other specific emergent aquatic plants have the characteristics of high flexibility and high height, and can swing along with water flow and extend upwards out of the water surface, so that the aim of blocking suspended sand in water is fulfilled.
The emergent aquatic vegetation groups 8 are planted at the middle rear part of the upstream direction and the downstream direction of the second silt discharging area 2, so that water flow is not influenced by the emergent aquatic vegetation groups 8 when passing through the front half section of the second silt discharging area 2, more silt is focused to the outer side of the silt discharging area (arc section) under the action of centrifugal force, and the silt is more beneficial to sedimentation after being concentrated in a water body; and the second desilting area 2 is because the first half section (the half section that is close to first desilting area 1) does not plant emergent aquatic vegetation, therefore the whole flow resistance in second desilting area 2 is littleer, is favorable to reducing water pump power.
In order to accurately select a proper plant, the flexural modulus of the plant selected by the submerged vegetation and the flexural modulus of the emergent aquatic plant need to be defined.
The flexural modulus of elasticity E of the vegetation is expressed as:
wherein F is the transverse load borne by the plant, L is the length of the plant, I is the moment of inertia of the plant, and u is the offset distance of the vegetation end point (highest point) when being impacted by water flow;
the moment of inertia I of the plant is:
；
wherein d is the diameter of the plant stem;
e is more than 1 for the submerged vegetation in the first desilting area 1;
for emergent aquatic vegetation in the second silt discharging area 2, E is less than 0.1.
The submerged vegetation E in the first silt discharging area 1 is more than 1, so that the submerged vegetation has proper rigidity to block bed load (coarse sand) near a riverbed, and the submerged vegetation is prevented from being bent due to the fact that the submerged vegetation cannot bear the thrust of the bed load, and further the effect of blocking the coarse sand is greatly reduced. Emergent aquatic vegetation E in the second silt discharging area 2 is less than 0.1, so that the emergent aquatic vegetation has proper rigidity to swing along with water flow. The value of the E value is convenient for selecting proper submerged vegetation and emergent vegetation from various plants.
The radius of the arc of the second desilting area 2 is more than or equal to 0.8 kilometer and less than or equal to 1.6 kilometers. If the radius of the curve of the second silt discharging area 2 is too large, the centrifugal action is too weak, and the effect of throwing silt to the outer side for sedimentation cannot be achieved obviously. If the radius of the curve of the second dredging area 2 is too small, the effect of sudden turning appears, so that the flow resistance is greatly increased, and the dredging efficiency is reduced. In order to realize better dredging effect, the applicant firstly proposes a target of considering both centrifugal action and water body flow resistance, under the guidance of the target, through calculation and experiments, the most appropriate curve radius of 0.8-1.6 kilometers is determined, and the optimum curve radius of the second dredging area 2 is 1.2 kilometers.
The flow gradient of the first dredging area 1 is preferably 0.5 per thousand, the flow gradient of the second dredging area 2 is preferably 0.7 per thousand, and the flow gradient of the third dredging area 3 is preferably 1 per thousand.
The invention also discloses a yellow river 11 dredging method which is carried out by adopting the continuous water diversion dredging site suitable for the middle and lower reaches of the yellow river 11, the water diversion gate 4 is kept in an open state, the water pump is opened to pump water into the first dredging area 1, when water flow passes through the first dredging area 1, coarse sand in the water enters the high barrier area 6 under the action of gravity and is deposited on the river bed of the first dredging area 1 under the action of the submerged vegetation group 5; the low flow resistance area 7 of the first silt discharging area 1 enables water flow to smoothly enter the second silt discharging area 2;
in the process that water flows in the first half section of the second desilting area 2, fine sand in the water body is concentrated to the outer side of the second desilting area 2 under the action of centrifugal force, and the concentrated fine sand can be more effectively settled; when the water flow passes through the emergent aquatic vegetation group 8 of the second silt discharging area 2, the fine sand in the water is blocked by the emergent aquatic vegetation group 8 and sinks to the river bed of the second silt discharging area 2 under the action of gravity;
after the water flow enters the third silt discharging area 3, the water flow flows back into the yellow river 11 rapidly because the third silt discharging area 3 has the largest flow direction gradient in the three areas.
Although the present invention has been described in detail with reference to the above embodiments, it should be understood by those skilled in the art that: modifications and equivalents may be made thereto without departing from the spirit and scope of the invention and it is intended to cover in the claims the invention as defined in the appended claims.
Claims (8)
1. Yellow river middle and lower reaches are diversion desilting place in succession based on vegetation and bend, its characterized in that: comprises a U-shaped water diversion and silt discharge area,
the U shape comprises two side edges and an arc section connecting the two side edges, the arc section of the water diversion dredging area forms a second dredging area, and the water diversion dredging area on the two sides of the second dredging area is a first dredging area and a third dredging area respectively; the gradient of the riverbed of the water diversion and silt removal area along the water flow direction is called as the flow direction gradient;
the first dredging area is used for blocking and settling coarse sand, the second dredging area is used for blocking and settling fine sand, and the third dredging area is used for guiding water back to the yellow river;
the end parts of the first desilting area and the third desilting area are communicated with the yellow river, the flowing direction of water is taken as the downstream direction, and the first desilting area to the third desilting area are sequentially arranged from the upstream direction to the downstream direction; a diversion gate is arranged at the position where the first desilting area is communicated with the yellow river, and a water pump for pumping water into the first desilting area is arranged at the diversion gate;
submerged vegetation groups for intercepting coarse sand are planted in the first silt discharging area, the vegetation height of the submerged vegetation groups is less than or equal to MAX cm, the average water depth of the first silt discharging area is greater than or equal to 2MAX cm, water flow at the submerged vegetation groups is a high-obstruction area of the first silt discharging area, and a water flow area above the submerged vegetation groups forms a low-flow-resistance area of the first silt discharging area; emergent aquatic vegetation groups are planted in the second dredging area;
the flow direction gradient from the first desilting area to the third desilting area is increased in sequence; the lengths of the first desilting area, the second desilting area and the third desilting area are all more than or equal to 4 kilometers.
2. The vegetation and curve based continuous water diversion and silt removal field in yellow river of claim 1, which is characterized in that:
the vegetation height of the submerged vegetation group is less than or equal to 50 cm; the average water depth of the first desilting area is more than or equal to 100 cm; the planting density of the submerged vegetation group is 28-32 plants per square meter;
the vegetation height of the emergent aquatic vegetation group is more than 1.5 meters, the top end of the emergent aquatic vegetation group is higher than the water surface, and the planting density is 15-17 plants per square meter.
3. The vegetation and curve based continuous water diversion and silt removal field in yellow river of claim 1, which is characterized in that: the second silt discharging area is an arc-shaped section, and the riverbed at the radial outer side of the arc-shaped section is lower than the riverbed at the radial inner side.
4. The vegetation and curve based continuous water diversion and silt removal field in yellow river of claim 1, which is characterized in that: at the joint of the first dredging area and the second dredging area, the riverbed of the second dredging area is at least 0.5 m higher than that of the first dredging area; and at the joint of the second desilting area and the third desilting area, the river bed of the third desilting area is at least 0.3 m higher than that of the second desilting area.
5. The vegetation and curve based continuous water diversion and desilting place in yellow river middle and downstream according to any one of claims 1 to 4, characterized in that:
the submerged vegetation group is planted by one or more of curly pondweed, Li's standing grain, bermuda grass, Buddha's grass or suaeda glauca:
the emergent aquatic vegetation group is formed by planting one or more of reed, cattail or rhizoma alismatis;
emergent aquatic vegetation groups are planted at the middle rear part of the upstream direction and the downstream direction of the second silt discharging area.
6. The vegetation and curve based continuous water diversion and desilting place in yellow river middle and downstream according to any one of claims 1 to 4, characterized in that: the flexural modulus of elasticity E of the vegetation is expressed as:
wherein F is the transverse load borne by the plant, L is the length of the plant, I is the moment of inertia of the plant, and u is the offset distance of the vegetation end point when the vegetation end point is impacted by water flow;
the moment of inertia I of the plant is:
(ii) a Wherein d is the diameter of the plant stem;
for submerged vegetation in the first desilting area, E is more than 1;
and E is less than 0.1 for emergent aquatic vegetation in the second silt discharging area.
7. The vegetation and curve based continuous water diversion and silt removal field in yellow river of claim 6, wherein:
the radius of the arc of the second dredging area is more than or equal to 0.8 kilometer and less than or equal to 1.6 kilometers.
8. The yellow river desilting method based on the vegetation and curve in the yellow river middle and downstream continuous water diversion desilting field in claim 7 is characterized in that:
keeping the water diversion gate in an open state, opening a water pump to pump water into the first dredging area, and when water flow passes through the first dredging area, coarse sand in the water enters the high-blocking area under the action of gravity and is deposited on a riverbed of the first dredging area under the action of submerged vegetation groups; the low flow resistance area of the first silt discharging area enables water flow to smoothly enter the second silt discharging area;
in the process that water flows in the first half section of the second dredging area, fine sand in the water body is concentrated to the outer side of the second dredging area under the action of centrifugal force, and the concentrated fine sand can be more effectively settled; when the water flow passes through the emergent aquatic vegetation group of the second desilting area, the fine sand in the water is blocked by the emergent aquatic vegetation group and sinks to the riverbed of the second desilting area under the action of gravity;
after the water flow enters the third desilting area, the third desilting area has the largest flow direction gradient in the three areas, so the water flow quickly flows back to the yellow river.
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| CN204662344U (en) * | 2015-03-25 | 2015-09-23 | 广东省水利水电科学研究院 | The anti-silting system of a kind of convex bank diversion |
| CN106731047A (en) * | 2017-03-01 | 2017-05-31 | 三峡大学 | A kind of grating type desilting device |
| CN208500669U (en) * | 2018-05-25 | 2019-02-15 | 云南农业大学 | A kind of movable ecological mattress |
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