An automatic drainage type weir structure protected from environmental influences

Abstract

The present invention discloses an automatic drainage type weir structure that is protected from the environment, comprising a weir body, a rain-proof device in front of the weir, a backflow prevention device behind the weir, and an automatic drainage device; the backflow prevention device behind the weir is located in the downstream area of the weir plate, and the backflow prevention device behind the weir can be hermetically connected to the left and right sides and the bottom of the weir body to prevent water from flowing back during high downstream water levels; the automatic drainage device is used to drain the water between the weir plate and the backflow prevention device behind the weir to the downstream side of the backflow prevention device behind the weir to maintain the water level requirement between the weir plate and the backflow prevention device behind the weir; the rain-proof device in front of the weir is used to block rain from entering the weir body and eliminate the influence of rainfall on the upstream inflow. By combining "upper blocking" and "lower drainage", the influence of rainwater and backflow on the water levels upstream and downstream of the weir plate is eliminated, and accurate measurement of the flow rate is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of water conservancy projects and relates to an automatic drainage type weir structure that is not affected by the environment. Background Art

[0002] A weir is a device that calculates the water volume passing through the weir section per unit time by measuring the head of the weir crest. The earliest and most commonly used is the thin-walled weir with a special notch, which can be divided into several types such as triangular weir, trapezoidal weir, rectangular weir, and curved weir. The thin-walled weir has the characteristics of simple manufacturing, easy installation, low cost, and high accuracy, so it is widely used for the seepage flow monitoring of hydraulic structures such as the dams and engineering slopes of conventional hydropower stations or pumped storage power stations. Measuring the flow rate through the weir is an important part of the safety monitoring of hydraulic structures, and strengthening the flow rate monitoring is of extremely important significance for ensuring the safety of hydraulic structures.

[0003] The basic principle of weir measurement is to convert the upstream water level of the weir plate into flow rate through the weir flow formula or the pre-drawn water level - flow rate chart. In addition, when the water flow passes through the notch of the weir plate, there are two flow states: free overflow and submerged outflow. Among them, free overflow has better measurement accuracy, and this flow state requires a certain water head difference before and after the weir plate. In actual application of traditional weirs, the water levels before and after the weir plate are inevitably affected by external environmental factors such as rainfall and backwater, which brings great errors to flow rate measurement.

[0004] Therefore, how to reduce or even avoid the influence of external environmental factors such as rainfall and backwater on the water levels before and after the weir plate has become an urgent problem to be solved in the accurate flow measurement of the weir. Summary of the Invention

[0005] Objective: In order to overcome the deficiencies in the prior art, the present invention provides an automatic drainage type weir structure that is not affected by the environment. By combining "upper blocking" and "lower drainage", the influence of rainwater and backwater on the upstream and downstream water levels of the weir plate of the weir is eliminated, and accurate flow measurement is achieved; at the same time, the overall structure is simple, the production and installation are convenient, it is easy to repair and maintain, and it can be installed on the original traditional weir body.

[0006] Technical Solution: To solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0007] In the first aspect, an automatic drainage type weir structure that is not affected by the environment is provided, including a weir body of the weir, a rain-proof device in front of the weir, a backwater prevention device behind the weir, and an automatic drainage device;

[0008] A weir plate is arranged in the weir body of the weir along the cross-section in the water flow direction. The weir plate divides the weir body of the weir into an upstream area of the weir plate and a downstream area of the weir plate, and is used to measure the water flow rate at the weir plate;

[0009] The post-weir anti-backflow device is located in the downstream area of the weir plate, and the post-weir anti-backflow device can be hermetically connected to the left and right sides and the bottom of the water measuring weir body to prevent the backflow of water when the downstream water level is high.

[0010] The automatic drainage device is used to drain the water between the weir plate and the post-weir anti-backflow device to the downstream side of the post-weir anti-backflow device to maintain the water level requirement between the weir plate and the post-weir anti-backflow device.

[0011] The pre-weir rain-proof device is at least arranged in the upstream area of the weir plate and above the weir plate to block rainfall from entering the weir body and eliminate the influence of rainfall on the upstream water inflow.

[0012] In some embodiments, the post-weir anti-backflow device is a fixed wall structure or a vertically movable gate structure.

[0013] In some embodiments, the post-weir anti-backflow device is arranged parallel to the weir plate.

[0014] In some embodiments, the top elevation of the post-weir anti-backflow device is greater than the maximum possible water level elevation on the downstream side of the post-weir anti-backflow device.

[0015] In some embodiments, the pre-weir rain-proof device includes a rain-blocking sub-structure, a water-collecting sub-structure, and a water-draining sub-structure; wherein the rain-blocking sub-structure is inclined and arranged in the upstream area of the weir plate and above the weir plate to the post-weir anti-backflow device, and the lower end of the rain-blocking sub-structure extends to the downstream side of the post-weir anti-backflow device; along the length direction of the water measuring weir body, water-collecting sub-structures in the form of gutter structures are respectively arranged on both sides of the water measuring weir body, the water-draining sub-structure connects the water-collecting sub-structures to the downstream of the post-weir anti-backflow device, and both sides of the rain-blocking sub-structure are above the water-collecting sub-structures or extend outside the water-collecting sub-structures.

[0016] In some embodiments, the automatic drainage device includes a low-level drainage sub-device and a high-level drainage sub-device.

[0017] The low-level drainage sub-device includes a low-level drainage pipe and a valve arranged on the low-level drainage pipe. The low-level drainage pipe penetrates through the post-weir anti-backflow device, and the inlet of the low-level drainage pipe is located on the upstream side of the post-weir anti-backflow device, and the outlet of the low-level drainage pipe is located on the downstream side of the post-weir anti-backflow device.

[0018] The high-level drainage sub-device includes a high-level drainage pipe and a water pump for driving drainage; the water pump is connected to the high-level drainage pipe, the inlet of the high-level drainage pipe is located on the upstream side of the post-weir anti-backflow device, the outlet of the high-level drainage pipe is located on the downstream side of the post-weir anti-backflow device, and the outlet of the high-level drainage pipe is higher than the highest water level on the downstream side of the post-weir anti-backflow device.

[0019] In some embodiments, the automatic drainage device further includes an automatic switching switch, which is used to control the startup of the low-level drainage sub-device and the high-level drainage sub-device.

[0020] In some embodiments, automatic water level gauges are respectively arranged on the upstream side and the downstream side of the backwater prevention device behind the weir, which are respectively used to monitor the water level values on the upstream side and the downstream side of the backwater prevention device behind the weir and transmit them to the automatic drainage control device. The automatic drainage control device judges the water level values on the upstream side and the downstream side of the backwater prevention device behind the weir and issues an instruction to the automatic switching switch to control the switching between the low-level drainage sub-device and the high-level drainage sub-device.

[0021] Second, a working method of the automatic drainage type water measuring weir structure protected from the environment is provided, including:

[0022] Read the water level values on the upstream side and the downstream side of the backwater prevention device behind the weir through the automatic water level gauges respectively;

[0023] (A) If the backwater prevention device behind the weir is a fixed structure:

[0024] When the water level downstream of the backwater prevention device behind the weir is lower than the water level upstream, the high-level drainage sub-device is selected to be closed through the automatic switching switch, while the low-level drainage sub-device is started and the valve is opened to reduce the water level behind the weir plate in a self-flow form through the drain pipe;

[0025] When the water level downstream of the backwater prevention device behind the weir is higher than the water level upstream, the low-level drainage sub-device is selected to be closed through the automatic switching switch, the high-level drainage sub-device is started, and the water pump is turned on to reduce the water level behind the weir plate in a forced drainage form of the water pump through the drain pipe;

[0026] (B) If the backwater prevention device behind the weir is a movable structure:

[0027] When the water level downstream of the backwater prevention device behind the weir is lower than the water level upstream, the high-level drainage sub-device is selected to be closed through the automatic switching switch, and the backwater prevention device behind the weir moves up and opens to reduce the water level behind the weir plate in a self-flow form;

[0028] When the water level downstream of the backwater prevention device behind the weir is higher than the water level upstream, the backwater prevention device behind the weir is selected to be closed through the automatic switching switch, and at the same time, the high-level drainage sub-device is started and the water pump is turned on to reduce the water level behind the weir plate in a forced drainage form of the water pump through the drain pipe.

[0029] Beneficial effects: The automatic drainage type water measuring weir structure protected from the environment provided by the present invention excludes the influence of rainwater and backwater on the water levels upstream and downstream of the weir plate of the water measuring weir through the combination of "upper blocking" and "lower drainage", and realizes accurate measurement of flow rate. It has the following advantages:

[0030] (1)Integrating the "upper blocking" and "lower discharging" methods respectively eliminates the influence of rainwater on the upstream water level of the weir plate and the backwater on the downstream water level of the weir plate;

[0031] (2)Components such as the rain-proof device in front of the weir, the backwater-proof device behind the weir, and the automatic drainage device adopt a split structure, which is easy to replace when a part is damaged;

[0032] (3)This structure can be installed on the original traditional weir body without repeated investment;

[0033] (4)The overall structure is simple, easy to manufacture and install, and easy to repair and maintain. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is an overall three-dimensional view of the device according to an embodiment of the present invention;

[0035] Figure 2 It is an auxiliary view of the device according to an embodiment of the present invention;

[0036] Figure 3 It is a detailed view of the automatic drainage device in the device according to an embodiment of the present invention.

[0037] In the figure: water measuring weir body 1, weir plate 1-1, upstream of the weir plate 1-2, downstream of the weir plate 1-3, rain-proof device in front of the weir 2, rain-blocking sub-device 2-1, water-collecting sub-device 2-2, water-draining sub-device 2-3, backwater-proof device behind the weir 3, low-level drainage sub-device 4-1, high-level drainage sub-device 4-2, automatic change-over switch 4-3, automatic water level gauge 4-4. DETAILED DESCRIPTION OF THE INVENTION

[0038] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. The description of at least one exemplary embodiment below is actually only illustrative and in no way limits the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0039] Unless otherwise specifically stated, the relative arrangements of components and steps, numerical expressions, and numerical values set forth in these embodiments do not limit the scope of the present invention. At the same time, it should be understood that, for the sake of convenience of description, the dimensions of the various parts shown in the drawings are not drawn in actual proportional relationships. Technologies, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the said technologies, methods, and devices should be regarded as part of the authorization specification. In all the examples shown and discussed here, any specific value should be construed as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that: like reference numerals and letters denote like items in the following drawings, and thus, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0040] In the description of the present application, it should be understood that the orientation or positional relationships indicated by the terms "center", "longitudinal", "transverse", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be construed as a limitation on the protected content of the present invention.

[0041] In the present application, unless otherwise clearly specified and defined, the terms "installed", "connected", "connected", "fixed", etc. should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be directly connected, or indirectly connected through an intermediate medium, and may be the internal communication of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0042] Embodiment 1

[0043] As Figures 1 to 3 shown, an automatic drainage type weir structure protected from the environment includes a weir body 1, a rainproof device 2 in front of the weir, a backflow prevention device 3 behind the weir, and an automatic drainage device;

[0044] In the weir body 1 of the weir, a weir plate 1-1 is provided in the cross-section along the water flow direction. The weir plate 1-1 divides the weir body 1 of the weir into an upstream area 1-2 of the weir plate and a downstream area 1-3 of the weir plate, and is used to measure the water flow rate at the weir plate;

[0045] The post-weir anti-backflow device 3 is located in the downstream area 1-3 of the weir plate, and the post-weir anti-backflow device 3 can be hermetically connected to the left and right sides and the bottom of the water measuring weir body 1, which is used to prevent the backflow of water body at high downstream water levels and reduce the influence of downstream water levels on the flow rate;

[0046] The automatic drainage device is used to drain the water body between the weir plate 1-1 and the post-weir anti-backflow device 3 to the downstream side of the post-weir anti-backflow device 3 to maintain the water level requirement between the weir plate 1-1 and the post-weir anti-backflow device 3;

[0047] The pre-weir rain-proof device 2 is at least arranged in the upstream area 1-2 of the weir plate and above the weir plate 1-1, which is used to block rainfall from entering the weir body and eliminate the influence of rainfall on the upstream water inflow.

[0048] In some embodiments, the post-weir anti-backflow device is located in the weir body or the river channel at a certain distance behind the weir plate.

[0049] In some embodiments, the automatic drainage device is located between the weir plate and the post-weir anti-backflow device.

[0050] In some embodiments, the post-weir anti-backflow device 3 is a fixed wall structure or a movable gate structure that can move up and down.

[0051] In some embodiments, the post-weir anti-backflow device 3 is arranged parallel to the weir plate.

[0052] In some embodiments, the top elevation of the post-weir anti-backflow device 3 is greater than the maximum possible water level elevation on the downstream side of the post-weir anti-backflow device.

[0053] The pre-weir rain-proof device is composed of three sub-structures: rain shielding, water collection, and water diversion. The rain shielding sub-structure is located above the weir body upstream of the weir plate to prevent rainwater from directly entering the weir body; the water collection sub-structure is located on both sides of the weir body to prevent surface runoff formed by rainfall from entering the weir body; the water diversion sub-structure leads from both sides of the weir body to the downstream of the post-weir anti-backflow device to realize the diversion of the blocked and collected rainwater to the downstream.

[0054] In some embodiments, such as Figure 1 、 Figure 2As shown in the figure, the rain-proof device 2 in front of the weir includes a rain-blocking sub-structure 2-1, a water-collecting sub-structure 2-2, and a water-draining sub-structure 2-3. Among them, the rain-blocking sub-structure 2-1 is inclined and arranged above the upstream area 1-2 of the weir plate and above the weir plate to the backflow prevention device behind the weir. The lower end of the rain-blocking sub-structure 2-1 extends to the downstream side of the backflow prevention device 3 behind the weir. Along the length direction of the weir body 1 of the water measuring weir, water-collecting sub-structures 2-2 in the form of groove structures are respectively arranged on both sides of the weir body 1 of the water measuring weir. The water-draining sub-structure 2-3 connects the water-collecting sub-structure 2-2 to the downstream of the backflow prevention device 3 behind the weir. Both sides of the rain-blocking sub-structure 2-1 are located above the water-collecting sub-structure 2-2 or extend outside the water-collecting sub-structure 2-2. The blocked and collected rainwater is drained to the downstream of the backflow prevention device 3 behind the weir.

[0055] In some embodiments, as Figure 3 shown, the automatic drainage device includes a low-level drainage sub-device 4-1 and a high-level drainage sub-device 4-2;

[0056] The low-level drainage sub-device 4-1 includes a low-level drain pipe 4-1-1 and a valve 4-1-2 arranged on the low-level drain pipe 4-1-1. The low-level drain pipe 4-1-1 penetrates through the backflow prevention device 3 behind the weir, and the inlet of the low-level drain pipe 4-1-1 is located on the upstream side of the backflow prevention device 3 behind the weir, and the outlet of the low-level drain pipe 4-1-1 is located on the downstream side of the backflow prevention device 3 behind the weir.

[0057] The high-level drainage sub-device 4-2 includes a high-level drain pipe 4-2-2 and a water pump 4-2-1 for driving drainage. The water pump 4-2-1 is connected to the high-level drain pipe 4-2-2. The inlet of the high-level drain pipe 4-2-2 is located on the upstream side of the backflow prevention device 3 behind the weir, and the outlet of the high-level drain pipe 4-2-2 is located on the downstream side of the backflow prevention device 3 behind the weir, and the outlet of the high-level drain pipe 4-2-2 is higher than the highest water level on the downstream side of the backflow prevention device 3 behind the weir.

[0058] In some specific embodiments, the inlet of the high-level drain pipe is located on the upper part of the bottom plate of the weir trough on the downstream side of the weir plate, and the outlet leads to the downstream side of the backflow prevention device behind the weir after passing through the top of the backflow prevention device behind the weir.

[0059] In some embodiments, the automatic drainage device further includes an automatic switch 4-3, and the automatic switch 4-3 is used to control and switch the startup conditions of the low-level drainage sub-device 4-1 and the high-level drainage sub-device 4-2.

[0060] In some embodiments, automatic water level gauges 4-4 are respectively arranged on the upstream side and the downstream side of the backflow prevention device behind the weir, which are respectively used to monitor the water level values on the upstream side and the downstream side of the backflow prevention device 3 behind the weir and transmit them to the automatic drainage control device. The automatic drainage control device judges the water level values on the upstream side and the downstream side of the backflow prevention device 3 and issues an instruction to the automatic changeover switch 4-3 to control the switching between the low-level drainage sub-device 4-1 and the high-level drainage sub-device 4-2.

[0061] When the backflow prevention device behind the weir is of a fixed structure, the low-level drainage sub-device of the automatic drainage device can be adopted; when the backflow prevention device behind the weir is of a movable structure, the low-level drainage sub-device may not be provided, and self-drainage is achieved by opening and moving up the backflow prevention device behind the weir.

[0062] The automatic drainage device is composed of a low-level drainage sub-device, a high-level drainage sub-device, an automatic changeover switch and two automatic water level gauges. The low-level drainage sub-device is composed of a low-level drainage pipe and a valve. When the water level downstream of the backflow prevention device behind the weir is lower than the inlet of the low-level drainage pipe, the valve opens to lower the water level behind the weir plate in a gravity flow form. When the water level downstream of the backflow prevention device behind the weir is higher than the inlet of the low-level drainage pipe, the valve closes to prevent backflow; the high-level drainage sub-device is composed of a high-level drainage pipe and a water pump. When the water level downstream of the backflow prevention device behind the weir is lower than the inlet of the low-level drainage pipe, the water pump closes. When the water level downstream of the backflow prevention device behind the weir is higher than the inlet of the low-level drainage pipe, the water pump starts, and the high-level drainage pipe is used to drain water downstream; the automatic changeover switch is connected to the valve of the low-level drainage sub-device and the water pump of the high-level drainage sub-device, and is used to switch the start of the high-level and low-level drainage sub-devices according to the water level conditions before and after the backflow prevention device behind the weir; the two automatic water level gauges are respectively installed in front of and behind the backflow prevention device behind the weir to measure the water levels in front of and behind the backflow prevention device behind the weir.

[0063] Embodiment 2

[0064] The working method of the automatic drainage type water measuring weir structure protected from the environment described in Embodiment 1 includes:

[0065] The water level values on the upstream side and the downstream side of the backflow prevention device 3 behind the weir are respectively read through the automatic water level gauges 4-4;

[0066] (A) If the backflow prevention device 3 behind the weir is of a fixed structure:

[0067] When the water level downstream of the backflow prevention device 3 behind the weir is lower than the water level upstream, the high-level drainage sub-device 4-2 is selected to be closed through the automatic changeover switch 4-3, while the low-level drainage sub-device 4-1 is started, and the valve 4-1-2 opens, so as to lower the water level behind the weir plate in a gravity flow form through the drainage pipe 4-1-1;

[0068] When the water level downstream of the backwater prevention device 3 behind the weir is higher than the water level upstream, the low-level drainage sub-device 4-1 is selected to be closed through the automatic changeover switch 4-3, the high-level drainage sub-device 4-2 is started, and the water pump 4-2-1 is turned on, so as to reduce the water level behind the weir plate in the form of strong drainage by the water pump through the drain pipe 4-2-2;

[0069] (B)If the backwater prevention device 3 behind the weir is a mobile structure:

[0070] When the water level downstream of the backwater prevention device 3 behind the weir is lower than the water level upstream, the high-level drainage sub-device 4-2 is selected to be closed through the automatic changeover switch 4-3, and the backwater prevention device 3 behind the weir is moved upward to be opened, so as to reduce the water level behind the weir plate in the form of gravity flow;

[0071] When the water level downstream of the backwater prevention device 3 behind the weir is higher than the water level upstream, the backwater prevention device 3 behind the weir is selected to be closed through the automatic changeover switch 4-3, and at the same time, the high-level drainage sub-device 4-2 is started, and the water pump 4-2-1 is turned on, so as to reduce the water level behind the weir plate in the form of strong drainage by the water pump through the drain pipe 4-2-2.

[0072] The above are only the preferred embodiments of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. An automatic drainage type weir structure protected from the environment, characterized in that, it includes a weir body of the weir, a rain-proof device in front of the weir, a backflow prevention device behind the weir, and an automatic drainage device; In the weir body of the weir, a weir plate is arranged in the cross-section along the water flow direction. The weir plate divides the weir body of the weir into an upstream area of the weir plate and a downstream area of the weir plate, and is used to measure the water flow rate at the weir plate; The backflow prevention device behind the weir is located in the downstream area of the weir plate, and the backflow prevention device behind the weir can be hermetically connected to the left, right sides and bottom of the weir body of the weir, and is used to prevent the water body from flowing back when the downstream water level is high; The automatic drainage device is used to drain the water body between the weir plate and the backflow prevention device behind the weir to the downstream side of the backflow prevention device behind the weir, and maintain the water level requirement between the weir plate and the backflow prevention device behind the weir; The rain-proof device in front of the weir is at least arranged in the upstream area of the weir plate and above the weir plate, and is used to block the rain from entering the weir body and eliminate the influence of rain on the upstream incoming water volume.

2. The automatic drainage type weir structure protected from the environment according to claim 1, characterized in that, the backflow prevention device behind the weir is a fixed wall structure or a movable gate structure that can move up and down.

3. The automatic drainage type weir structure protected from the environment according to claim 1, characterized in that, the backflow prevention device behind the weir is arranged parallel to the weir plate.

4. The automatic drainage type weir structure protected from the environment according to claim 1 or 2 or 3, characterized in that, the top elevation of the backflow prevention device behind the weir is greater than the maximum possible water level elevation on the downstream side of the backflow prevention device behind the weir.

5. The automatic drainage type weir structure protected from the environment according to claim 1, characterized in that, the rain-proof device in front of the weir includes a rain-blocking sub-structure, a water-collecting sub-structure and a water-draining sub-structure; wherein the rain-blocking sub-structure is inclined and arranged in the upstream area of the weir plate and above the weir plate to the backflow prevention device behind the weir, and the lower end of the rain-blocking sub-structure extends to the downstream side of the backflow prevention device behind the weir; along the length direction of the weir body of the weir, water-collecting sub-structures in the form of groove structures are respectively arranged on both sides of the weir body of the weir, and the water-draining sub-structure connects the water-collecting sub-structure to the downstream of the backflow prevention device behind the weir, and both sides of the rain-blocking sub-structure are above the water-collecting sub-structure or extend outside the water-collecting sub-structure.

6. The automatic drainage type weir structure protected from the environment according to claim 1, characterized in that, the automatic drainage device includes a low-level drainage sub-device and a high-level drainage sub-device; The low-level drainage sub-device includes a low-level drainage pipe and a valve arranged on the low-level drainage pipe. The low-level drainage pipe penetrates through the backflow prevention device behind the weir, and the inlet of the low-level drainage pipe is located on the upstream side of the backflow prevention device behind the weir, and the outlet of the low-level drainage pipe is located on the downstream side of the backflow prevention device behind the weir; The high-level drainage sub-device includes a high-level drainage pipe and a water pump for driving drainage; the water pump is connected to the high-level drainage pipe, the inlet of the high-level drainage pipe is located on the upstream side of the backflow prevention device behind the weir, the outlet of the high-level drainage pipe is located on the downstream side of the backflow prevention device behind the weir, and the outlet of the high-level drainage pipe is higher than the highest water level on the downstream side of the backflow prevention device behind the weir.

7. The automatic drainage type weir structure protected from the environment according to claim 6, It is characterized in that the automatic drainage device further includes an automatic changeover switch, which is used to control the startup conditions of the low-level drainage sub-device and the high-level drainage sub-device.

8. The automatic drainage type weir structure resistant to environmental impact according to claim 7, It is characterized in that automatic water level gauges are respectively arranged on the upstream side and the downstream side of the backwater prevention device behind the weir, which are respectively used to monitor the water level values on the upstream side and the downstream side of the backwater prevention device behind the weir, and transmit them to the automatic drainage control device. The automatic drainage control device judges the water level values on the upstream side and the downstream side of the backwater prevention device behind the weir, and issues an instruction to the automatic changeover switch to control the switching between the low-level drainage sub-device and the high-level drainage sub-device.

9. The working method of the automatic drainage type weir structure resistant to environmental impact according to any one of claims 1-8, It is characterized in that it includes: reading the water level values on the upstream side and the downstream side of the backwater prevention device behind the weir respectively through the automatic water level gauges; (A) If the backwater prevention device behind the weir is a fixed structure: When the water level downstream of the backwater prevention device behind the weir is lower than the water level upstream, the high-level drainage sub-device is selected to be closed through the automatic changeover switch, while the low-level drainage sub-device is started and the valve is opened, and the water level behind the weir plate is reduced in the form of gravity flow through the drain pipe; When the water level downstream of the backwater prevention device behind the weir is higher than the water level upstream, the low-level drainage sub-device is selected to be closed through the automatic changeover switch, the high-level drainage sub-device is started, and the water pump is turned on, and the water level behind the weir plate is reduced in the form of strong drainage by the water pump through the drain pipe; (B) If the backwater prevention device behind the weir is a movable structure: When the water level downstream of the backwater prevention device behind the weir is lower than the water level upstream, the high-level drainage sub-device is selected to be closed through the automatic changeover switch, and the backwater prevention device behind the weir moves up and opens, and the water level behind the weir plate is reduced in the form of gravity flow; When the water level downstream of the backwater prevention device behind the weir is higher than the water level upstream, the backwater prevention device behind the weir is selected to be closed through the automatic changeover switch, and at the same time the high-level drainage sub-device is started and the water pump is turned on, and the water level behind the weir plate is reduced in the form of strong drainage by the water pump through the drain pipe.

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