A small reservoir ecological flow measurement system and control method with high dynamic water level

Abstract

The present invention relates to a small reservoir ecological flow measurement system and control method with a high dynamic water level, belonging to the technical field of ecological flow transformation, and includes a dam, a sand flushing system, a discharge system, and a control system; through the effective combination of the dam, the sand flushing system, the discharge system, and the measurement and control system, and through the transformation of the sand flushing bottom hole and the linkage of each system, the present invention solves the problems of vibration, high-pressure water flow, and sediment deposition in traditional bottom hole discharge. On the premise of ensuring the structural safety, normal storage, and sand flushing function of the reservoir, it can realize real-time regulation of ecological flow, effectively ensure that the ecological flow in the downstream river reaches the standard. Through the transformation of the sand flushing bottom hole and the linkage of each system, compared with the current traditional ecological flow discharge method, it can realize real-time adjustment and guarantee of ecological flow under a higher dynamic water level change range, enhance the guarantee probability of ecological flow, and reduce the risk of ecological flow damage.

Description

Technical Field

[0001] The present invention relates to the technical field of ecological flow transformation, and particularly to a high-dynamic water level small reservoir ecological flow metering system and control method. Background Art

[0002] Approval and monitoring of ecological flow are important measures to maintain the structure and function of river and lake ecosystems. To further ensure the ecological flow of rivers, China's water administrative departments have carried out ecological flow review and monitoring work on existing river-blocking sluices, reservoirs, small hydropower stations, etc., and have started to establish an ecological flow monitoring system to ensure that flow data can be obtained daily and automatically reported to fully guarantee the compliance of the key ecological flow assessment sections downstream. As one of the most common river-blocking buildings, reservoirs are widely distributed in China with a large quantity. There are about 17,000 reservoirs in the Pearl River Basin alone, and small reservoirs account for more than 90%, mainly small type (II). Therefore, how to ensure the accurate discharge and metering of ecological flow in small reservoirs is crucial for ensuring the ecological flow downstream.

[0003] The current discharge of ecological flow in small reservoirs mainly has the following three methods: one is to discharge through the power generation tail water and use a pipeline flowmeter for metering; the second is to use the flood discharge channel for ecological flow discharge; the third is to use a preset scouring bottom hole for discharging. The first ecological flow discharge method has relatively high recording accuracy, but not all reservoirs have power generation plants. In addition, this scheme is greatly affected by the water level in the reservoir area. When the reservoir water level is lower than the designed power generation head or the water intake pipeline, power generation often stops and priority is given to ensuring production and domestic water, thereby affecting the normal discharge of ecological flow; the second method of using the flood discharge channel for ecological flow discharge will, on the one hand, generate complex turbulent structures and vibrations when the water level difference between upstream and downstream is large, and long-term operation will affect the overall structural stability and service life of the reservoir. On the other hand, under changing water level conditions, the relationship between different opening degrees and flow rates has large differences, making it difficult to accurately control the discharged flow rate; the third method of using the scouring bottom hole for discharging will also face problems such as high-speed water flow, complex turbulence and vibrations, and at the same time, it also faces the problem of blockage of the discharge facilities caused by sediment or silt.

[0004] Therefore, there is an urgent need for a method for ecological flow transformation, metering and control of small reservoirs with high-dynamic water levels, which can achieve accurate metering and real-time regulation of ecological flow at high-dynamic water levels on the basis of ensuring the safety and stability of the overall structure of the reservoir, and also has the advantages of simple structure, smooth water flow pattern, easy to use and durable. Summary of the Invention

[0005] The present invention overcomes the deficiencies of the prior art and provides a high-dynamic water level small reservoir ecological flow metering system and control method.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] In the first aspect of the present invention, a small reservoir ecological flow measurement system with high dynamic water level is provided, which includes a dam, a sand flushing system, a discharge system, and a control system.

[0008] The dam includes a working bridge, one end of the working bridge is connected to the dam body, and the other end is connected to the working room. Among them, a support structure is provided below the working room.

[0009] The sand flushing system includes a sand flushing bottom hole, which is located at the bottom of the dam body. Moreover, a sand flushing inlet section is provided at the inlet of the sand flushing bottom hole, and a gate and a gate chamber for controlling the opening and closing of the sand flushing bottom hole are provided in the sand flushing inlet section.

[0010] The discharge system includes the inlet end of the discharge pipeline, an angle valve, and the outlet end of the discharge pipeline. The inlet end of the discharge pipeline includes a pipe body and a trash rack. The trash rack is located at the front end of the inlet end of the discharge pipeline. The angle valve includes a pipe body, a valve core, an exhaust and water stop device, and a lifting rod. A trash rack is provided at the front end of the inlet end of the discharge pipeline, and the end is closely connected to the angle valve. The front end of the outlet end of the discharge pipeline is closely connected to the angle valve, and the end is closely connected and communicated with the sand flushing bottom hole.

[0011] The control system includes an electric hoist, a towing rope, a radar water level gauge, an electric elevator, a pipeline flowmeter, and a central control system. One end of the towing rope is connected to the gate, and the other end is connected to the electric hoist.

[0012] The radar water level gauge reads the upstream water level data of the reservoir in real time and transmits it to the central control system. The pipeline flowmeter is installed before the tail valve at the end of the sand flushing bottom hole and reads the real-time flow data of the sand flushing bottom hole in real time and transmits it to the central control system.

[0013] Furthermore, in this system, the end of the sand flushing bottom hole has a tail valve.

[0014] Furthermore, in this system, the central control system receives the real-time data transmitted by the radar water level gauge and the pipeline flowmeter and controls the electric hoist and the electric elevator.

[0015] Furthermore, in this system, the sand flushing bottom hole and the sand flushing inlet section are located below the dead water level.

[0016] Furthermore, in this system, one end of the inlet end of the discharge pipeline is located between the dead water level and the low water level in the dry season, and the other end is above the low water level in the dry season. Moreover, the height difference between the front end and the end of the inlet end of the discharge pipeline does not exceed the atmospheric pressure.

[0017] Furthermore, in this system, the angle valve is installed above the low water level in the dry season, and the valve core has a sealing device.

[0018] Further, in this system, the exhaust water stop device is located between the housing and the lifting rod. One end of the lifting rod is fixedly connected to the valve core, and the other end extends to the electric control lift in the working chamber.

[0019] Further, in this system, the electric control lift adjusts the opening degree of the angle valve by controlling the lifting of the lifting rod.

[0020] Further, in this system, the sand flushing bottom hole is one of a concrete pipeline or a penstock.

[0021] The second aspect of the present invention provides a control method for an ecological flow measurement system of a small reservoir with a high dynamic water level, which is applied to any one of the ecological flow measurement systems of the small reservoir with a high dynamic water level, and includes the following steps:

[0022] Step 1: In the form of a cofferdam, install the flow discharge device and the control system according to the dam form and layout, ensure that a trash rack is provided at the front end of the inlet end of the flow discharge pipeline, the end is closely connected to the angle valve, the front end of the outlet end of the flow discharge pipeline is closely connected to the angle, and the end is closely connected and communicated with the sand flushing bottom hole. Moreover, one end of the inlet end of the flow discharge pipeline is located between the dead water level and the low water level in the dry season, and the other end is above the low water level in the dry season. The height difference between the front end and the end of the inlet end of the flow discharge pipeline does not exceed the atmospheric pressure;

[0023] Step 2: Install and debug the equipment to ensure that the radar water level gauge reads the water level data of the upstream of the reservoir in real time and transmits it to the central control system. The pipeline flowmeter is installed before the tail valve at the end of the sand flushing bottom hole. The central control system can receive the real-time data transmitted by the radar water level gauge and the pipeline flowmeter and can control the electric control hoist 41 and the electric control lift 44 to realize the opening and closing and the opening degree adjustment of the gate and the angle valve 32;

[0024] Step 3: When h3 + △h < the reservoir water level h ≤ h4, at this time, the valve 23 is closed and the tail valve 25 is opened, and the sand flushing bottom hole 21 is emptied. According to the requirement of ecological flow discharge, the central control system controls the electric control lift 44 to drive the lifting rod 32d to move to adjust the opening degree of the angle valve 32, thereby controlling the discharge flow;

[0025] Step 4: Through the real-time flow data fed back by the pipeline flowmeter 45, dynamically judge whether the discharge requirement is met and adjust it in real time. The sand flushing bottom hole 21 is in a non-pressure flow state, and the radar water level gauge monitors the real-time changes of the reservoir area in real time;

[0026] Step 5: When h1 < reservoir water level h ≤ h3 + △h, when the radar water level gauge monitors that the upstream water level continues to drop and is close to the installation elevation of the angle valve, at this time, control the tail valve to close, and control the opening of the angle valve to slowly fill the scour bottom hole and the drainage device with water. The gas is discharged through the exhaust and water-stop device. At this time, a siphon effect has been formed inside the drainage device, and the regulation of the discharged ecological flow can be achieved by controlling the opening of the tail valve or the angle valve;

[0027] Step 6: When the reservoir water level is h ≤ h1: At this time, due to the low water level, the device can no longer discharge the ecological flow normally. When it is necessary to use the scour bottom hole for sediment flushing or water discharge, close the angle valve, open the tail valve, and then control the electric elevator to pull the gate for sediment flushing or water discharge through the central control system;

[0028] Among them, h4 is the distance from the dam bottom to the normal storage water level, h3 is the distance from the dam bottom to the angle valve water level, h2 is the distance from the dam bottom to the low water level in the dry season, h1 is the distance from the dam bottom to the trash rack at the bottom of the inlet end of the discharge pipeline, h0 is the distance from the dam bottom to the dead water level, and △h is a certain safety surplus water level, which is determined according to the water level - storage capacity curve and the diameter of the angle valve.

[0029] The present invention solves the defects existing in the background technology, and the present invention has the following beneficial effects:

[0030] On the one hand, the present invention effectively combines the dam, the scour system, the discharge system, and the measurement and control system. Through the transformation of the scour bottom hole and the linkage of each system, it solves the problems of vibration, high-pressure water flow, and sediment deposition in traditional bottom hole discharge. It can realize the real-time regulation of ecological flow on the premise of ensuring the structural safety, normal storage and scour function of the reservoir, and effectively ensure that the ecological flow in the downstream river reaches the standard. On the other hand, the present invention effectively combines the dam, the scour system, the discharge system, and the measurement and control system. Through the transformation of the scour bottom hole and the linkage of each system, compared with the current traditional ecological flow discharge method, it can realize the real-time regulation and guarantee of ecological flow under a higher dynamic water level change range, enhance the guarantee probability of ecological flow, and reduce the risk of ecological flow damage. The present invention proposes a method for ecological flow transformation, measurement and control of small reservoirs with high dynamic water levels, which is applicable to the ecological flow transformation of various small reservoirs and mountain ponds equipped with scour bottom holes, and has the advantages of simple structure, accurate measurement, and reliable regulation. In addition, by reasonably setting the height of the angle valve so that it is exposed above the water surface in the dry season, it is also convenient for the maintenance and management of the facilities. Description of the Drawings

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings of embodiments can also be obtained based on these drawings.

[0032] Figure 1 It is a schematic diagram of the main structure of the present invention;

[0033] Figure 2 It is a schematic diagram of the structure before the transformation of the present invention;

[0034] Figure 3 It is a schematic diagram of the main modified structure of the present invention;

[0035] Figure 4 It is a front view schematic diagram of the present invention;

[0036] Figure 5 It is a schematic diagram of the structure of the discharge system of the present invention;

[0037] Figure 6 It is a schematic diagram of the control system of the present invention;

[0038] In the figure:

[0039] 3. Discharge system; 11. Dam body; 12. Working room; 13. Support structure; 14. Working bridge; 21. Scouring sluice; 22. Scouring inlet section; 23. Gate; 24. Sluice chamber; 25. Tail valve; 31. Inlet end of the discharge pipeline; 31a. Pipe body; 31b. Trash rack; 32. Angle valve; 32a. Pipe body; 32b. Valve core; 32c. Exhaust and water stop device; 32d. Lifting rod; 33. Outlet end of the discharge pipeline; 41. Electric control hoist; 42. Towing rope; 43. Radar water level gauge; 44. Electric control elevator; 45. Pipeline flowmeter. Detailed implementation manners

[0040] In order to more clearly understand the above objects, features and advantages of the present invention, the present invention will be further described in detail below in conjunction with the drawings and specific implementation manners. These drawings are all simplified schematic diagrams, only illustrating the basic structure of the present invention in a schematic manner. Therefore, they only show the components related to the present invention. It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

[0041] In the description of the present application, it should be understood that the orientation or positional relationship indicated by terms such as "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present application 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. Therefore, it should not be construed as a limitation on the protection scope of the present application. In addition, terms such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Therefore, features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more.

[0042] In the description of the present application, it should be noted that unless otherwise clearly specified and defined, the terms "installed", "connected", "coupled" shall be construed in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood through specific circumstances.

[0043] To facilitate the understanding of the present invention, the present invention will be described more comprehensively below with reference to the relevant drawings. The preferred embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0044] As Figures 1 to 6 shown, the present invention provides a method for ecological flow transformation, measurement and control of a small reservoir with high dynamic water level, including a dam, a sand flushing system, a flow discharging system 3, and a control system;

[0045] The dam includes a dam body 11, a working chamber 12, a support structure 13, and a working bridge 14, which are structures commonly found in general reservoirs. The support structure 13 is located below the working chamber 12 to play a supporting role; one end of the working bridge 14 is connected to the dam body 11 and the other end is connected to the working chamber; the working chamber is used to control devices such as the sand flushing system.

[0046] The sand flushing system includes a sand flushing bottom hole 21, a sand flushing inlet section 22, a gate 23, a gate chamber 24, and a tail valve 25; the sand flushing bottom hole 21 is generally a concrete pipeline or a penstock and is located at the bottom of the dam body; a sand flushing inlet section 22 is provided at the inlet of the sand flushing bottom hole 21; a gate 23 and a gate chamber 24 for controlling the opening and closing of the sand flushing bottom hole 21 are provided in the sand flushing inlet section 22; the end of the sand flushing bottom hole 21 has a tail valve 25.

[0047] The flow discharging system 3 includes a flow discharging pipeline inlet end 31, an angle valve 32, and a flow discharging pipeline outlet end 33. The flow discharging pipeline inlet end 31 includes a pipe body 31a and a trash rack 31b, and the trash rack 31b is located at the front end of the flow discharging pipeline inlet end 31; the angle valve 32 includes a pipe body 32a, a valve core 32b, an exhaust and water stop device 32c, and a lifting rod 32d; a trash rack 31b is provided at the front end of the flow discharging pipeline inlet end 31, and the end is closely connected to the angle valve 32; the front end of the flow discharging pipeline outlet end 33 is closely connected to the angle valve 32, and the end is closely connected and communicated with the sand flushing bottom hole.

[0048] The control system includes an electric control hoist 41, a towing rope 42, a radar water level gauge 43, an electric control elevator 44, a pipeline flowmeter 45, and a central control system. One end of the towing rope 42 is connected to the gate 23, and the other end is connected to the electric control hoist 41; the radar water level gauge 43 can read the water level data of the upstream of the reservoir in real time and transmit it to the central control system; the electric control elevator 44 can control the lifting of the lifting rod 32d; the pipeline flowmeter 45 should be installed before the tail valve 25 at the end of the sand flushing bottom hole 21 and can read the real-time flow data of the sand flushing bottom hole 21 in real time and transmit it to the central control system; the central control system can receive the real-time data transmitted by the radar water level gauge 43 and the pipeline flowmeter 45 and can control the electric control hoist 41 and the electric control elevator 44.

[0049] The sand flushing bottom hole 21 and the sand flushing inlet section 22 should be located below the dead water level.

[0050] One end of the flow discharging pipeline inlet end 31 should be located at an appropriate position between the dead water level and the low water level in the dry season, and the other end should be located above the low water level in the dry season; the height difference between the front end and the end of the flow discharging pipeline inlet end 31 should not exceed the atmospheric pressure.

[0051] The angle valve 32 should be installed above the low water level in the dry season; the valve core 32b should have a sealing device; the exhaust and water stop device 32c is located between the housing 32a and the lifting rod 32d; one end of the lifting rod 32d is fixedly connected to the valve core 32b, and the other end extends to the electric control elevator 44 in the working room 12.

[0052] The electric control elevator 44 can adjust the opening degree of the angle valve by controlling the lifting of the lifting rod 32d.

[0053] The operating principle of the present invention is as follows:

[0054] In the first step, through forms such as cofferdams, install the flow discharge device 3 and the control system according to the dam form and layout as shown in Figure 1 , Figure 3 , Figure 4 . Ensure that a trash rack 31b is provided at the front end of the inlet end 31 of the flow discharge pipeline, and the end is closely connected to the angle valve 32. The front end of the outlet end 33 of the flow discharge pipeline is closely connected to the angle valve 32, and the end is closely connected and communicated with the scouring bottom hole. Moreover, one end of the inlet end 31 of the flow discharge pipeline should be located at an appropriate position between the dead water level and the low water level in the dry season, and the other end should be located above the low water level in the dry season. The height difference between the front end and the end of the inlet end 31 of the flow discharge pipeline should not exceed the atmospheric pressure.

[0055] In the second step, install and debug the equipment to ensure that the radar water level gauge 43 can read the upstream water level data of the reservoir in real time and transmit it to the central control system. The pipeline flowmeter 45 should be installed before the tail valve 25 at the end of the scouring bottom hole 21. The central control system can receive the real-time data transmitted by the radar water level gauge 43 and the pipeline flowmeter 45 and can control the electric hoist 41 and the electric elevator 44 to realize the opening and closing and opening degree adjustment of the gate 23 and the angle valve 32.

[0056] So far, the device is installed and can operate normally. For the convenience of explanation, let h4 be the distance between the bottom of the dam and the normal storage level, h3 be the distance between the bottom of the dam and the water level of the angle valve 32, h2 be the distance between the bottom of the dam and the water level in the dry season, h1 be the distance between the bottom of the dam and the trash rack at the bottom of the inlet end 31 of the flow discharge pipeline, h0 be the distance between the bottom of the dam and the dead water level, and △h be a certain safety surplus water level, which should be determined according to the water level~storage capacity curve and the diameter of the angle valve 32.

[0057] There are mainly three situations during the operation of the device, which are respectively:

[0058] ① When h3 + △h < the reservoir water level h ≤ h4: At this time, the valve 23 is closed and the tail valve 25 is opened, and the scouring bottom hole 21 is emptied. It is necessary to control the opening degree of the angle valve 32 by driving the lifting rod 32d to move through the central control system according to the ecological flow discharge requirement, so as to control the discharge flow, and dynamically judge whether it meets the discharge requirement and adjust it in real time through the real-time flow data fed back by the pipeline flowmeter 45. Since the control of general small reservoirs is based on a small area, the ecological flow is usually below 0.05 m³ / s, and the scouring bottom hole 21 is usually in an unpressurized flow state, without obvious vibration or high-pressure water flow, and has little impact on the dam safety. During this process, the radar water level gauge 43 should monitor the real-time changes of the reservoir area in real time.

[0059] ②h1 < reservoir water level h ≤ h3 + △h: When the radar water level gauge 32 monitors that the upstream water level is continuously decreasing and is close to the installation elevation h3 of the angle valve 32 (or it is judged in combination with the incoming water situation that the reservoir water level may drop below h3), the tail valve 25 should be controlled to close at this time, and the opening of the angle valve 32 should be controlled so that the water slowly fills the sand flushing bottom hole 21 and the water discharge device 3. The gas is discharged through the exhaust and water stop device 32c. At this time, a siphon effect has been formed inside the water discharge device 3, and the regulation of the downstream ecological flow can be achieved by controlling the opening of the tail valve 25 or the angle valve 32. The rest of the principle is the same as in situation ①. At this time, the average flow velocity in the sand flushing bottom hole 21 is relatively slow, and basically no vibration will occur. Coupled with the low upstream water level and the siphon effect, the water pressure in the sand flushing bottom hole 21 is relatively small, and the impact on the dam safety is relatively small.

[0060] ③Reservoir water level h ≤ h1: At this time, due to the low water level, the device cannot discharge the ecological flow normally.

[0061] When it is necessary to use the sand flushing bottom hole for sand flushing or water discharge, the angle valve 32 should be closed first, the tail valve 25 should be opened, and then the central control system should be used to control the electric control elevator 44 to pull the gate 23 for sand flushing or water discharge.

[0062] According to the actual situation and the definition of ecological flow, generally, the incoming flow upstream of the sluice will still be greater than the ecological flow discharge under the condition of the driest month. Coupled with the other more abundant incoming water months, the reservoir water level generally mostly stays in the first and second states. The third state mostly appears in the extremely dry month of an extremely dry year. At this time, according to the corresponding management measures, a certain degree of ecological flow damage is allowed.

[0063] To sum up, on the one hand, the present invention effectively combines the dam, the sand flushing system, the water discharge system, and the measurement and control system. Through the transformation of the sand flushing bottom hole and the linkage of each system, it solves the problems of vibration, high-pressure water flow, and sediment deposition in the traditional bottom hole water discharge. It can realize the real-time regulation of the ecological flow on the premise of ensuring the structural safety, normal water storage and sand flushing functions of the reservoir, and effectively ensure that the ecological flow in the downstream river reaches the standard. On the other hand, the present invention effectively combines the dam, the sand flushing system, the water discharge system, and the measurement and control system. Through the transformation of the sand flushing bottom hole and the linkage of each system, compared with the current traditional ecological flow discharge method, it can realize the real-time adjustment and guarantee of the ecological flow under a higher dynamic water level change range, enhance the guarantee probability of the ecological flow, and reduce the risk of ecological flow damage. The present invention proposes a method for ecological flow transformation, measurement and control of small reservoirs with high dynamic water levels, which is applicable to the ecological flow transformation of various small reservoirs and mountain ponds equipped with sand flushing bottom holes, and has the advantages of simple structure, accurate measurement, and reliable adjustment. In addition, by reasonably setting the height of the angle valve so that it is exposed above the water surface during the dry season, it is also convenient for the maintenance and management of the facilities.

[0064] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0065] Based on the ideal embodiments of the present invention as inspiration, through the above description, relevant personnel can completely make various changes and modifications without departing from the technical idea of this invention. The technical scope of this invention is not limited to the content in the specification, and the technology must be determined according to the scope of the claims.

Claims

1. A high dynamic water level small reservoir ecological flow metering system, including a dam, a sand flushing system, a discharge system and a control system, characterized in that: The dam comprises a working bridge, one end of which is connected to the dam body, and the other end of which is connected to a workroom, wherein a supporting structure is arranged below the workroom; The sand flushing system includes a sand flushing bottom hole, which is located at the bottom of the dam body, and a sand flushing entrance section is provided at the entrance of the sand flushing bottom hole, and a gate and a gate chamber for controlling the opening and closing of the sand flushing bottom hole are provided in the sand flushing entrance section; The drainage system includes a drainage pipe inlet, an angle valve, and a drainage pipe outlet. The drainage pipe inlet includes a pipe body and a trash rack. The trash rack is located at the front end of the drainage pipe inlet. The angle valve includes a pipe body, a valve core, an exhaust and water-stopping device, and a lifting rod. A trash rack is provided at the front end of the drainage pipe inlet, and the end is in close contact with the angle valve. The front end of the drainage pipe outlet is in close contact with the angle valve, and the end is in close contact with and connected to the sand flushing bottom hole. The control system includes an electric-controlled hoist, a traction rope, a radar water level gauge, an electric-controlled lift, a pipeline flow meter and a central control system, wherein one end of the traction rope is connected to the gate and the other end is connected to the electric-controlled hoist; The radar water level meter reads the water level data of the upstream of the reservoir in real time and transmits it to the central control system. The pipeline flow meter is installed before the tail valve at the end of the sand flushing bottom hole, and reads the real-time flow data of the sand flushing bottom hole in real time and transmits it to the central control system.

2. According to claim 1, a high dynamic water level small reservoir ecological flow metering system is characterized in that: The central control system receives real-time data transmitted by the radar water level meter and the pipeline flow meter and controls the electric-controlled hoist and the electric-controlled lift.

3. The high dynamic water level small reservoir ecological flow metering system according to claim 1 is characterized in that: The sand flushing bottom hole and the sand flushing inlet section are located below the dead water level.

4. The high dynamic water level small reservoir ecological flow metering system according to claim 1 is characterized in that: One end of the inlet end of the leakage pipe is located between the dead water level and the low water level in the dry season, and the other end is located above the low water level in the dry season, and the height difference between the front end and the end of the inlet end of the leakage pipe does not exceed the atmospheric pressure.

5. The high dynamic water level small reservoir ecological flow metering system according to claim 1 is characterized in that: The angle valve is installed above the low water level in the dry season, and the valve core has a sealing device.

6. The high dynamic water level small reservoir ecological flow metering system according to claim 1 is characterized in that: One end of the lifting rod is fixed to the valve core, and the other end extends to the electric-controlled lifting machine in the workshop.

7. The high dynamic water level small reservoir ecological flow metering system according to claim 1 is characterized in that: The electric control lifter adjusts the opening of the angle valve by controlling the lifting and lowering of the lifting rod.

8. The high dynamic water level small reservoir ecological flow metering system according to claim 1 is characterized in that: The sand flushing bottom hole is a concrete pipe or a pressure steel pipe.

9. A control method for an ecological flow metering system of a small reservoir with a high dynamic water level, characterized in that: The high dynamic water level small reservoir ecological flow metering system applied to any one of claims 1 to 8 comprises the following steps: Step 1: Install the discharge device and control system according to the dam form and layout through the cofferdam form, ensure that the front end of the discharge pipe inlet is equipped with a trash rack, the end is closely connected with the angle valve, the front end of the discharge pipe outlet is closely connected with the angle, the end is closely connected with the sand flushing bottom hole and connected, and one end of the discharge pipe inlet is located between the dead water level and the low water level in the dry season, and the other end is located above the low water level in the dry season, and the height difference between the front end and the end of the discharge pipe inlet does not exceed the atmospheric pressure; Step 2: Install and debug the equipment to ensure that the radar water level meter reads the water level data upstream of the reservoir in real time and transmits it to the central control system. The pipeline flow meter is installed before the tail valve at the end of the sand flushing bottom hole. The central control system can receive the real-time data transmitted by the radar water level meter and the pipeline flow meter and control the electric control jack and the electric control lift to realize the opening and closing and opening adjustment of the gate and angle valve; Step 3: When h3+△h<reservoir water level h≤h4, the valve is closed and the tail valve is opened, the sand flushing bottom hole is emptied, and according to the ecological flow discharge requirements, the central control system controls the electric control lift to drive the lifting rod to adjust the angle valve opening, thereby controlling the discharge flow; Step 4: Through the real-time flow data fed back by the pipeline flow meter, dynamically determine whether the discharge requirements are met and make real-time adjustments. The sand flushing bottom hole is in a pressure-free flow state, and the radar water level meter monitors the real-time reservoir changes in the reservoir area in real time; Step 5: When h1<reservoir water level h≤h3+△h, when the radar water level gauge detects that the upstream water level continues to drop and approaches the installation elevation of the angle valve, the tail valve is controlled to be closed, and the angle valve opening is controlled to allow the water flow to slowly fill the sand flushing bottom hole and the water discharge device, wherein the gas is discharged through the exhaust water stop device. At this time, a siphon effect has been formed inside the water discharge device, and the downstream ecological flow can be regulated by controlling the tail valve or angle valve opening; Step 6: When the reservoir water level is at h≤h1: At this time, due to the low water level, the device can no longer discharge the ecological flow normally. When it is necessary to activate the sand flushing bottom hole for sand flushing or flow discharge, close the angle valve, open the tail valve, and then control the electric control crane through the central control system to pull the gate for sand flushing or flow discharge; Among them, h4 is the distance between the dam bottom and the normal water storage level, h3 is the distance between the dam bottom and the angle valve water level, h2 is the distance between the dam bottom and the dry season water level, h1 is the distance between the dam bottom and the trash rack at the bottom of the spillway inlet, h0 is the distance between the dam bottom and the dead water level, and △h is a certain safe surplus water level, which is determined according to the water level-reservoir capacity curve and the angle valve diameter.

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