River channel water volume measuring method under multi-gate control

Abstract

The invention discloses a riverway water volume measurement method under multi-gate control, which comprises the following steps: according to an upstream water depth h1 measured by a water level sensor in front of a gate, re-measuring by adopting a field water level flow relationship, and calculating a low water level flow Q0 of a corresponding water level; empirical parameters [mu] 0 and [delta] s are accurately and reversely calculated according to a free outflow or submerged outflow formula in gate hole outflow through a flow Q1 calculated by a gate port flow measurement system and a flow Q2 calculated by a water level monitoring system before and after a gate; according to the field outflow type, mu0 and delta s are substituted to calculate the river flow Q3 when the flow is difficult to measure accurately; the problem that the water volume of the river channel is difficult to accurately measure under the conditions that the opening height of the gates is changed and the multi-stage gates interfere with one another is solved, and the river channel flow monitoring precision under multi-gate control is improved.

Description

Technical Field

[0001] The invention relates to a water area monitoring technology, and in particular to a river water volume measurement method under multi-gate control. Background Art

[0002] Most areas of Yunnan have distinct dry and wet seasons, and the precipitation is unevenly distributed throughout the year. The precipitation in the flood season (May-October) accounts for 75.3% of the annual precipitation, and the maximum precipitation in four consecutive months accounts for 66.0% of the annual precipitation, mostly concentrated in May-August or June-September. The seasonal differences in the functions of rivers (ditches) are obvious. In the rainy season, they are used for flood discharge and drainage, and in the dry season, they are used to store water resources and supply water for regional agricultural production. Many gates are arranged in the river to meet the needs of river discharge, flood control and water storage. However, the hydrological situation of the river flow measurement process under the control of the gate is unstable, the flow rate changes rapidly, and the sediment content is high, which seriously affects the monitoring of river water volume and the accuracy of data, especially in the basins of the nine plateau lakes. Agricultural non-point source pollution has become the main source of basin pollution. The pollution load comes with the water. The process of pollution entering the lake is the process of water entering the lake. Accurately monitoring the amount of water entering the lake under the control of the gate is of great significance for accurately evaluating the contribution of agricultural non-point source pollutants to the lake flux.

[0003] The existing water volume monitoring method is the single gate water flow section flow measurement method, which uses a Doppler flowmeter to measure the flow at the bottom of the gate and calculate the flow through the gate. However, this method cannot meet the water volume monitoring requirements of rivers where the opening and closing processes of multiple gates interfere with each other, and the water volume monitoring accuracy is low. Summary of the invention

[0004] The purpose of the present invention is to solve the defects of the above-mentioned prior art and provide a method for measuring river water volume under multi-gate control.

[0005] The present invention adopts the following technical solution:

[0006] A method for measuring water volume in a river under multi-gate control, comprising:

[0007] Low water level flow measurement:

[0008] When the water level in the river is low, the flow Q0 corresponding to the water level is calculated by retesting the on-site water level-flow relationship based on the upstream water depth h1 measured by the water level sensor in front of the gate;

[0009] Medium and high water level flow measurement:

[0010] ① According to the flow velocity v0, the water depth h0 and the gate hole width b measured by the radar flow sensor, calculate the flow Q1 corresponding to the water level;

[0011] ② According to the water depth h1 upstream of the gate and the water depth h2 downstream of the gate determined by the water level sensor before the gate and the water level sensor after the gate respectively, calculate the flow rate Q2 corresponding to the water level;

[0012] ③ Based on the outflow water depth h0 determined by the radar flow sensor and the gate opening height e determined by the gate position sensor; if e ≥ h0, the free outflow flow formula is used Calculate the flow rate Q3; if e<h0, use the flooded outflow flow formula Calculate flow rate Q3;

[0013] Among them, μ0 is the discharge coefficient during free outflow; b is the gate width; e is the gate opening height; h0 is the water depth at the gate; δ s is the flooding coefficient of the gate hole; g is the acceleration of gravity; μ0, δ s It is an empirical parameter determined according to the hydraulic calculation manual, combined with the relative gate opening e / h1, the type of gate and gate bottom plate;

[0014] The flow rates Q1 and Q2 calculated by steps ① and ② are substituted into the flow rate formula of the two cases in step ③ to calculate the empirical parameters μ0 and δ s , a large number of μ0, δ are obtained through multiple calculations s After continuously correcting the empirical parameters, we can obtain accurate μ0 and δ s numerical value; the obtained accurate μ0, δ s Substitute the flow formulas for the two situations in step ③ to accurately calculate the high water level river flow Q3 in real time.

[0015] Preferably, the flow rates Q1 and Q2 are calculated by establishing a water level-flow relationship curve through interpolation.

[0016] Preferably, when measuring the flow at low water level, artificial excavation is carried out along the mid-channel line of the river channel, and the river channel section in front of the gate is transformed into a compound section, so that the scattered water is concentrated in one place for measurement, and a low water level flow measurement system is constructed by the water level sensor in front of the gate and the flow compound section. The real-time water level data h1 is obtained through the water level sensor in front of the gate, and the water level-flow relationship is established through artificial re-measurement to accurately determine the flow rate in the low water level state of the river channel.

[0017] The method for measuring water volume in a river channel under multi-gate control provided by the present invention continuously corrects the empirical parameters μ0, δ in the free outflow or submerged outflow calculation formula by using the flow Q1 calculated by the gate flow measurement system, the flow Q2 calculated by the water level monitoring system before and after the gate, and the flow Q3 calculated by the free outflow or submerged outflow. s， Through the accumulation of a large amount of data, after constantly correcting and obtaining empirical calculation parameters, the free outflow or submerged outflow formula is used to estimate the river flow when it is difficult to accurately measure the flow. This solves the problem that the water volume in the river is difficult to accurately measure due to the great difference in water inflow between dry and rainy seasons and the multi-level gates controlled by humans, and the gate opening height changes and the interference of multiple gates.

[0018] When measuring flow at low water levels, artificial excavation is carried out along the central line of the river channel to gather scattered water into one place for measurement. Real-time water level data h1 is obtained through the water level sensor in front of the gate. The water level-flow relationship is established through artificial re-measurement to accurately determine the flow rate in the low water level state of the river channel, thereby solving the problem of difficult monitoring of water volume in the dry season when the water level is too low and the flow rate is too slow. For natural rivers with high water and sediment content and easy siltation, the water volume monitoring accuracy is low, which improves the flow monitoring accuracy in the dry season when the water level is low and the flow rate is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is the layout diagram of the river water quantity measurement system;

[0020] Figure 2 yes Figure 1 Sectional view along AA direction;

[0021] Among them: 1-gate, 2-gate position sensor, 31-water level sensor before the gate, 32-water level sensor after the gate, 4-radar flow sensor. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention is described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] like Figure 1 and Figure 2 As shown in the figure, the river water volume measurement system consists of a gate position sensing system, a water level monitoring system, a gate flow measurement system, and a flow calculation system. The four systems are organically combined and relatively independently operated, realizing water volume monitoring in rivers with large differences in dry and rainy seasons, prone to siltation, and affected by the opening and closing of multiple gates.

[0024] Gate position sensing system: This system consists of gate 1 and gate position sensor 2. The gate opening height e is determined by gate position sensor 2, and the cross-sectional area A=be of the lower edge of the gate is determined in combination with the gate hole width b.

[0025] Water level monitoring system: The system consists of two radar water level sensors, including a pre-gate water level sensor 31 and a post-gate water level sensor 32. The pre-gate water level sensor 31 and the post-gate water level sensor 32 respectively determine the water depth h1 upstream of the gate and the water depth h2 downstream of the gate.

[0026] When the water level in the river is low, the gate is generally in an open state. At this time, the amount of water is small, and it is difficult to flatten the entire riverbed. The water flows in the river in one or more small streams. The water flow section is extremely irregular, the amount of water is small and scattered, and it is difficult to measure the flow rate with existing monitoring equipment. Therefore, it is necessary to establish a low-water level flow measurement system to concentrate the scattered water in one place for measurement. Through manual excavation, excavation is carried out along the middle line of the river to the right, and earthwork is filled to the left side of the middle line. The river section in front of the gate is transformed into a compound section. At this time, the water level monitoring system is composed of a water level sensor 31 in front of the gate and a flow compound section, which is located on the upper side of the gate. The real-time water level data h1 is obtained through the water level sensor 31 in front of the gate, and the water level-flow relationship is established through manual re-measurement to accurately determine the flow rate in the low water level state of the river.

[0027] Gate flow measurement system: This system is composed of a radar flow sensor 4, which determines the gate water depth h0 and flow velocity v0.

[0028] Flow calculation system: This system calculates the cross-section flow rate by combining multiple methods such as on-site water level-flow relationship, free outflow or submerged outflow, and solves the problem of interference of opening and closing of multiple gates on cross-section flow monitoring.

[0029] The present invention proposes a method for measuring water volume in a river channel under multi-gate control based on the above system:

[0030] 1. Low water level flow measurement:

[0031] Low water level flow measurement system: Based on the upstream water depth h1 measured by the water level sensor 31 before the gate, the flow rate Q0 at the corresponding water level is calculated by re-measuring the on-site water level flow relationship.

[0032] Low water level means that when re-testing the relationship between water level and flow on site, the water depth of the river cannot be lower than the minimum working water level of most cup and propeller flow meters on the market, which is 0.05-0.2m. When the water level of the river is lower than its minimum working water level, it will affect the on-site flow velocity re-measurement of the river, so the low water level is limited to <0.2m.

[0033] 2. Medium and high water level flow measurement:

[0034] When the water level is medium or high, the amount of water coming in is relatively large, and the river water can be fully spread in the river channel, covering the entire river section. At this time, the water volume monitoring is only affected by the gate opening or closing process. The flow measurement method includes the following steps:

[0035] ① Gate flow measurement system: Based on the flow velocity v0, gate water depth h0, gate hole width b measured by the radar flow sensor 4, a water level flow relationship curve is established and the corresponding water level real-time flow Q1 is calculated by interpolation method;

[0036] ②Water level monitoring system before and after the gate: According to the upstream and downstream water depths h1 and h2, the on-site water level and flow relationship is re-measured, and the flow Q2 corresponding to the water level is calculated by interpolation method by establishing a water level and flow relationship curve;

[0037] ③ Calculate the flow rate Q3 by using the free outflow or submerged outflow according to the outflow water depth h0 and the gate opening height e. If e ≥ h0, use the free outflow flow formula Calculate the flow rate Q3; if e<h0, use the flooded outflow flow formula Calculate the flow rate Q3.

[0038] Among them, μ0 is the discharge coefficient during free outflow; b is the gate width; e is the gate opening height; h0 is the water depth at the gate; δ s is the flooding coefficient of the gate hole; g is the acceleration of gravity. μ0, δ s The value can be determined based on the hydraulic calculation manual, combined with the relative gate opening e / h1, the type of gate and gate bottom plate, etc.

[0039] Specifically, according to the "Hydraulic Calculation Manual", the flow coefficient μ0 = εφ, ε is the vertical contraction coefficient, φ is the flow velocity coefficient, and both coefficients can be found in the table.

[0040] The ε of the flat gate in the table can only be within the range of 0.1-0.65 of the gate relative opening value, with one ε corresponding to each interval of 0.05, and the ε value range is 0.615-0.675.

[0041] φ is the range value under a specific gate orifice type, and the value range of φ is 0.85-1.00; both coefficients cannot fully fit the on-site conditions.

[0042] Through on-site measurement, a large amount of data on several parameters such as flow rate Q, gate hole width b, and gate opening height e are obtained. The two parameters ε and φ are constantly corrected and adjusted to finally obtain the flow coefficient μ. 0。 According to the Hydraulic Calculation Manual, the flooding coefficient of the gate hole δ s It is related to parameters such as μ0, gate opening height, water depth before the gate, and water depth after the gate. The hole flooding coefficient δ s The range is between 0 and 1. Through on-site measurement, a large amount of data on the gate opening height, water depth before the gate, and water depth after the gate are obtained. On the basis of the corrected flow coefficient μ0, δ is continuously corrected and adjusted. s。

[0043] According to Q1, Q2, and Q3, the parameters of each calculation formula are continuously revised to ultimately determine the amount of water in the river controlled by multiple gates under medium and high water levels.

[0044] Because there is no water inflow or withdrawal between the monitoring points Q1, Q2, and Q3, the values ​​of Q1, Q2, and Q3 should be equal in theory. s It is mainly related to the conditions of the river channel and the gate itself. Therefore, when the outflow situation is simple, through the accumulation of a large amount of data and continuous correction of the calculation experience parameters, the river flow when it is difficult to accurately measure the flow can be estimated through the free outflow or submerged outflow formula.

[0045] The flow rates Q1 and Q2 calculated by step ① and step ② are substituted into the flow formula of the two cases in step ③ to calculate the empirical parameters of the free outflow flow coefficient μ0 and the gate hole flooding coefficient δ s , a large number of μ0, δ are obtained through multiple calculations s After continuously correcting the empirical parameters, we can obtain accurate μ0 and δ s Numeric value.

[0046] The obtained accurate μ0, δ s By substituting the flow formulas of the two situations in step ③, the water volume of the high-water-level river can be accurately calculated in real time. Combined with the low-water-level measured flow rate Q0, the accurate river water volume in different situations can be obtained.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for measuring water volume in a river under multi-gate control, characterized in that include: Low water level flow measurement: When the water level in the river is low, the flow rate Q0 corresponding to the water level is calculated by retesting the water level and flow rate relationship on site based on the upstream water depth h1 measured by the water level sensor (31) before the gate; Medium and high water level flow measurement: ① Calculate the flow rate Q1 corresponding to the water level based on the flow velocity v0, the water depth h0 and the gate hole width b measured by the radar flow sensor (4); ② Calculate the flow rate Q2 corresponding to the water level according to the water depth h1 upstream of the gate and the water depth h2 downstream of the gate determined by the water level sensor (31) before the gate and the water level sensor (32) after the gate respectively; ③ Based on the water depth h0 determined by the radar flow sensor (4) and the gate opening height e determined by the gate position sensor (2); if e ≥ h0, the free outflow flow formula is used Calculate the flow rate Q3; if e<h0, use the flooded outflow flow formula Calculate flow rate Q3; Among them, μ0 is the discharge coefficient during free outflow; b is the gate width; e is the gate opening height; h0 is the water depth at the gate; δ s is the flooding coefficient of the gate hole; g is the acceleration of gravity; μ0, δ s It is an empirical parameter determined according to the hydraulic calculation manual, combined with the relative gate opening e / h1, the type of gate and gate bottom plate; The flow rates Q1 and Q2 calculated by steps ① and ② are substituted into the flow rate formula of the two cases in step ③ to calculate the empirical parameters μ0 and δ s , a large number of μ0, δ are obtained through multiple calculations s After continuously correcting the empirical parameters, we can obtain accurate μ0 and δ s numerical value; the obtained accurate μ0, δ s Substitute the flow formulas for the two situations in step ③ to accurately calculate the high water level river flow Q3 in real time.

2. The method for measuring water volume in a river under multi-gate control as claimed in claim 1, characterized in that: Flow Q1 and flow Q2 are calculated by establishing a water level-flow relationship curve using the interpolation method.

3. The method for measuring water volume in a river under multi-gate control as claimed in claim 1, characterized in that: When measuring the flow at low water level, artificial excavation is carried out along the middle line of the river channel to transform the river channel section in front of the gate into a compound section, so that the scattered water is concentrated in one place for measurement. A low water level flow measurement system is constructed by the water level sensor (31) in front of the gate and the flow compound section. Real-time water level data h1 is obtained through the water level sensor (31) in front of the gate. The water level-flow relationship is established through artificial repeated measurement to accurately determine the flow rate in the low water level state of the river channel.

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