A method and terminal for calculating water replacement rate of plain river network based on remote sensing images

Abstract

The present invention discloses a method and terminal for calculating water volume replacement rate of a plain river network based on remote sensing images, and establishes a water surface area-water level fitting relationship between the water surface area of ​​a plain river network enclosed area water system and the water level of the water system through remote sensing images; the first water volume between the lowest water level of the plain river network enclosed area water system and the water level of each water system is calculated by the difference method, and the second water volume below the lowest water level is calculated by the volume generalization formula method, and the two are added to obtain the total water volume of the enclosed area water system corresponding to each water system water level, so as to establish the water level-water volume fitting relationship and the water surface area-water volume fitting relationship of the plain river network enclosed area water system; then, the total water volume of the current enclosed area water system at the current moment is obtained according to the above fitting relationship, so as to calculate the water volume replacement rate. The present invention can obtain the water volume replacement rate in real time, and its accuracy meets the calculation requirements of the water volume quality exchange of the river network water system, so as to timely grasp the water volume scheduling situation of the enclosed area, and has strong practicality.

Description

Technical Field

[0001] The present invention relates to the technical field of water ecological environment governance, and in particular to a method and a terminal for calculating water replacement rate of a plain river network based on remote sensing images. Background Art

[0002] Water replacement is the process of introducing new water to replace old water. It is an important method to improve the water environment of river networks. The water replacement rate, that is, the proportion of new water to the total water volume, reflects the degree of water replacement and is an important indicator for evaluating the effect of water quality improvement.

[0003] The calculation methods of water replacement rate are mainly water quality model simulation method and remote sensing estimation of river water volume method. Among them, the water quality model, also known as the water quality mathematical model, is a mathematical description of the law of water quality change in the water body. It determines the degree of water replacement by simulating the concentration change of the tracer in the river. Through reasonable assumptions, the numerical relationship between the tracer concentration and the water replacement rate is established, and then a mathematical model is established based on the water body continuity equation, motion equation and convection diffusion equation, and simulation calculations are performed. Finally, the concentration changes at different locations are analyzed to obtain the water replacement rate. In the process of building the model, it is necessary to input known boundary conditions, such as initial concentration, boundary concentration, river boundary water level or flow, and cross-sectional shape along the river.

[0004] The water quality model simulation method is mature in theory and relatively accurate, but the modeling workload is large and time-consuming, and the quality requirements of the measured boundary conditions are high. In the modeling process, the river section shape data is required as the model boundary condition. In actual engineering, especially in the case of a river network with many water systems, the river section shape data is not easy to obtain and the field measurement has a large workload, which greatly restricts the application of this method in actual engineering. In the actual measurement of the river section shape, the river section shape between the two measured sections is often measured at intervals along the way, and the river section shape between the two measured sections is obtained by interpolation, which also affects the accuracy of the simulation calculation. In addition, the roughness of the river channel is not easy to measure, and the roughness value also has a great influence on the model simulation results.

[0005] As for the remote sensing method for estimating river water volume, a technical solution that has been applied for is: using the extracted basin shape (catchment area) to crop the remote sensing image of the basin, and then using ENVI software to identify the water surface part in the cropped remote sensing image to obtain the area ratio it occupies, and then multiplying the basin area by the water surface area ratio to obtain the water surface area of ​​the basin. Then, the relationship between the water surface area and the runoff of the corresponding year of the remote sensing image is fitted to achieve the estimation of river water volume through the water surface area.

[0006] The above remote sensing estimation method is difficult to measure river runoff, especially in plain river networks, where it is difficult to have enough measurement stations. Moreover, the relationship analysis using the data from the flow station can only solve the control area of ​​the station, and cannot calculate the entire water system area. For the above reasons, the existing methods have the problems of difficulty in obtaining the measured river boundary conditions, inaccuracy, and large modeling workload, which will cause the dilemma of being out of touch with reality and difficult to apply. Summary of the invention

[0007] The technical problem to be solved by the present invention is to provide a method and a terminal for calculating the water replacement rate of a plain river network based on remote sensing images, so as to obtain the water replacement rate in real time and accurately.

[0008] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0009] A method for calculating water replacement rate of plain river network based on remote sensing images, including:

[0010] Step S1, establishing a water surface area-water level fitting relationship between the water surface area of ​​the water system in the plain river network enclosure and the water level of the water system through remote sensing images;

[0011] Step S2, calculating the first water volume from the river water body between the lowest water level of the plain river network enclosed area water system and the first water system water level according to the difference method and the water surface area-water level fitting relationship;

[0012] Step S3, calculating the second water volume below the lowest water level of the plain river network enclosed area water system by using the volume generalization formula method, and adding the first water volume and the second water volume to obtain the total water volume of the enclosed area water system corresponding to the first water system water level;

[0013] Step S4, repeating the above steps S2 and S3 until the total water volume of the water system in the plain river network enclosed area corresponding to the water level of each water system in the plain river network enclosed area is obtained, and a water level-water volume fitting relationship and a water surface area-water volume fitting relationship of the plain river network enclosed area water system are established;

[0014] Step S5, obtaining the new water inflow into the current enclosed area water system of the plain river network at the current moment, and obtaining the total water volume of the current enclosed area water system at the current moment from the water level-water volume fitting relationship according to the current water level of the current water system monitored by the key control point of the current water system at the current moment, or obtaining the total water volume of the current enclosed area water system at the current moment from the water surface area-water volume fitting relationship according to the water surface area of ​​the current water system at the current moment, and dividing the new water inflow into the current enclosed area at the current moment by the total water volume of the current enclosed area water system to obtain the water volume replacement rate.

[0015] In order to solve the above technical problems, another technical solution adopted by the present invention is:

[0016] A terminal for calculating water replacement rate of a plain river network based on remote sensing images, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the following is achieved:

[0017] Step S1, establishing a water surface area-water level fitting relationship between the water surface area of ​​the water system in the plain river network enclosure and the water level of the water system through remote sensing images;

[0018] Step S2, calculating the first water volume from the river water body between the lowest water level of the plain river network enclosed area water system and the first water system water level according to the difference method and the water surface area-water level fitting relationship;

[0019] Step S3, calculating the second water volume below the lowest water level of the plain river network enclosed area water system by using the volume generalization formula method, and adding the first water volume and the second water volume to obtain the total water volume of the enclosed area water system corresponding to the first water system water level;

[0020] Step S4, repeating the above steps S2 and S3 until the total water volume of the water system in the plain river network enclosed area corresponding to the water level of each water system in the plain river network enclosed area is obtained, and a water level-water volume fitting relationship and a water surface area-water volume fitting relationship of the plain river network enclosed area water system are established;

[0021] Step S5, obtaining the new water inflow into the current enclosed area water system of the plain river network at the current moment, and obtaining the total water volume of the current enclosed area water system at the current moment from the water level-water volume fitting relationship according to the current water level of the current water system monitored by the key control point of the current water system at the current moment, or obtaining the total water volume of the current enclosed area water system at the current moment from the water surface area-water volume fitting relationship according to the water surface area of ​​the current water system at the current moment, and dividing the new water inflow into the current enclosed area at the current moment by the total water volume of the current enclosed area water system to obtain the water volume replacement rate.

[0022] The beneficial effects of the present invention are: a method and terminal for calculating the water replacement rate of a plain river network based on remote sensing images, which establishes a water surface area-water level fitting relationship between the water surface area of ​​a plain river network enclosed area water system and the water level of the water system through remote sensing images, and then divides the total water volume of the enclosed area water system into two parts, one of which is calculated by a difference method, and the other is calculated by a volume generalization formula method, so as to quickly and accurately establish a water level-water volume fitting relationship and a water surface area-water volume fitting relationship of a plain river network enclosed area water system, thereby avoiding a complex water quality model method with high data requirements, and no need The river section measurement work is carried out on the complex and huge river network; then, by obtaining the current new water inflow into the plain river network enclosed area water system at the current moment, and according to the current water level of the current water system at the current moment from the water level-water volume fitting relationship or according to the current water surface area of ​​the current water system at the current moment from the water surface area-water volume fitting relationship, the total water volume of the current enclosed area water system is obtained, and the water volume replacement rate is calculated in real time. That is, the present invention can obtain the water volume replacement rate in real time, and its accuracy meets the calculation requirements of the water volume quality exchange of the river network water system, so as to timely grasp the water volume scheduling situation of the enclosed area, and has strong practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A schematic diagram of a flow chart of a method for calculating water replacement rate of a plain river network based on remote sensing images according to an embodiment of the present invention;

[0024] Figure 2 The present invention is a schematic structural diagram of a terminal for calculating water replacement rate of a plain river network based on remote sensing images according to an embodiment of the present invention.

[0025] Description of labels:

[0026] 1. A terminal for calculating water replacement rate of a plain river network based on remote sensing images; 2. A processor; 3. A memory. DETAILED DESCRIPTION

[0027] In order to explain the technical content, achieved objectives and effects of the present invention in detail, the following is an explanation in conjunction with the implementation modes and the accompanying drawings.

[0028] Please refer to Figure 1 , a method for calculating water replacement rate of plain river network based on remote sensing images, including:

[0029] Step S1, establishing a water surface area-water level fitting relationship between the water surface area of ​​the water system in the plain river network enclosure and the water level of the water system through remote sensing images;

[0030] Step S2, calculating the first water volume from the river water body between the lowest water level of the plain river network enclosed area water system and the first water system water level according to the difference method and the water surface area-water level fitting relationship;

[0031] Step S3, calculating the second water volume below the lowest water level of the plain river network enclosed area water system by using the volume generalization formula method, and adding the first water volume and the second water volume to obtain the total water volume of the enclosed area water system corresponding to the first water system water level;

[0032] Step S4, repeating the above steps S2 and S3 until the total water volume of the water system in the plain river network enclosed area corresponding to the water level of each water system in the plain river network enclosed area is obtained, and a water level-water volume fitting relationship and a water surface area-water volume fitting relationship of the plain river network enclosed area water system are established;

[0033] Step S5, obtaining the new water inflow into the current enclosed area water system of the plain river network at the current moment, and obtaining the total water volume of the current enclosed area water system at the current moment from the water level-water volume fitting relationship according to the current water level of the current water system monitored by the key control point of the current water system at the current moment, or obtaining the total water volume of the current enclosed area water system at the current moment from the water surface area-water volume fitting relationship according to the water surface area of ​​the current water system at the current moment, and dividing the new water inflow into the current enclosed area at the current moment by the total water volume of the current enclosed area water system to obtain the water volume replacement rate.

[0034] From the above description, we can know that the water surface area-water level fitting relationship between the water surface area and the water level of the plain river network water system is established through remote sensing images, and then the total water volume of the water system in the enclosed area is divided into two parts, one of which is calculated by the difference method, and the other is calculated by the volume generalization formula method, so as to quickly and accurately establish the water level-water volume fitting relationship and the water surface area-water volume fitting relationship of the plain river network water system, thereby avoiding the complex and data-intensive water quality model method, and there is no need to conduct river section analysis on the complex and huge river network. Measurement work; then, by obtaining the current new water inflow into the plain river network enclosed area water system at the current moment, and according to the current water system water level at the current moment from the water level-water volume fitting relationship or according to the current water system water surface area at the current moment from the water surface area-water volume fitting relationship, the total water volume of the current enclosed area water system is obtained, and the water volume replacement rate is obtained in real time. That is, the present invention can obtain the water volume replacement rate in real time, and its accuracy meets the calculation requirements of the water volume quality exchange of the river network water system, so as to timely grasp the water volume scheduling situation of the enclosed area, and has strong practicality.

[0035] Furthermore, the step S1 specifically includes the following steps:

[0036] Through remote sensing images, the water surface area of ​​the plain river network water system at every moment is obtained;

[0037] The weighted average of the water level data of all water level stations in the water system of the plain river network enclosed area at each corresponding moment is used as the water system water level of the water system of the plain river network enclosed area at each moment;

[0038] A water surface area-water level fitting relationship is established based on the corresponding relationship between the water surface area and the water level of the water system in the plain river network enclosure at each moment.

[0039] From the above description, it can be seen that since the gradient within the water system of the plain river network enclosed area will not be too large, the weighted average of the water level data of all water level stations in the water system of the plain river network enclosed area is used as the water level of the water system in the enclosed area at each moment. The above water level calculation is also applicable to obtaining the current water system water level at the current moment in step S5, thereby reducing the amount of water level calculation and ensuring the real-time nature of the water replacement rate.

[0040] Furthermore, the step S2 specifically includes the following steps:

[0041] The river water body between the lowest water level of the water system in the plain river network enclosure and the water level of the first water system is divided into multiple layers of layered water bodies, and the water surface areas of the upper and lower layers of each layer of the layered water body are obtained based on the water surface area-water level fitting relationship;

[0042] The water volume of each layer of the layered water body is obtained by multiplying the average water surface area of ​​the upper and lower layers of each layer of the layered water body by the water level difference between adjacent layers, and the water volumes of all the layered water bodies are accumulated to obtain the first water volume.

[0043] From the above description, it can be seen that when the thickness of each layer of the layered water body is small, the layered water body can be approximately regarded as a prism, and the first water volume can be quickly calculated using the formula for calculating the volume of a prism.

[0044] Furthermore, the step S5 of obtaining the current amount of new water flowing into the plain river network enclosed area at the current moment specifically includes the following steps:

[0045] The real-time data of the opening degree of the water-passing structure and the water level before and after the water system in the plain river network enclosure are connected, and the flow rate newly flowing into the water system in the plain river network enclosure at the current moment is calculated according to the flow type of the water system in the plain river network enclosure, the opening degree of the water-passing structure, the real-time data of the water level before and after the water system and the hydrodynamic flow formula;

[0046] From the initial moment of water replacement to the current moment of calculating the replacement rate, the flow change process of the water-passing buildings during this period is counted, and the new water inflow of the current enclosure is obtained based on the flow change process.

[0047] Furthermore, the step S5 of calculating the flow rate of the new flow into the plain river network enclosed area water system at the current moment according to the flow type of the plain river network enclosed area water system, the opening of the water-passing structure, the real-time data of the front and rear water levels and the hydrodynamic flow formula specifically includes the following steps:

[0048] When the sluice opening e and the water head h in front of the sluice areu The ratio is less than or equal to 0.65 and the water head behind the gate h d Less than the water depth after the jump h c When the flow type of the water system in the plain river network enclosure is free outflow from the gate hole, the flow formula is:

[0049]

[0050] In the formula, Q is the gate flow rate, n is the number of gate openings, b is the width of a single gate hole, and μ is the gate hole flow coefficient. The expression is:

[0051]

[0052] In the formula, is the velocity coefficient, ε is the vertical contraction coefficient, and the polynomial fitting is as follows:

[0053] ε=0.402(e / h u ) 3 -0.255(e / h u ) 2 +0.0985(e / h u )+0.6073.

[0054] Furthermore, the step S5 of calculating the flow rate of the new flow into the plain river network enclosed area water system at the current moment according to the flow type of the plain river network enclosed area water system, the opening of the water-passing structure, the real-time data of the front and rear water levels and the hydrodynamic flow formula specifically includes the following steps:

[0055] When the sluice opening e and the water head h in front of the sluice are u The ratio is less than or equal to 0.65 and the water head behind the gate h d Greater than or equal to the water depth after the jump h c When the flow type of the water system in the plain river network enclosure area is the flooding outflow of the sluice hole, the flow formula is:

[0056]

[0057] In the formula, Q is the gate flow rate, n is the number of gate openings, b is the width of a single gate hole, and μ is the gate hole flow coefficient. The expression is:

[0058]

[0059] In the formula, is the velocity coefficient, ε is the vertical contraction coefficient, and the polynomial fitting is as follows:

[0060] ε=0.402(e / h u ) 3-0.255(e / h u ) 2 +0.0985(e / h u )+0.6073;

[0061] In the formula, σ h is the flooding coefficient, and its expression is:

[0062]

[0063] α c =(h d -h c ) / (h u -h c );

[0064]

[0065] h z =εe;

[0066] In the formula, α c is the undercurrent ratio, h z is the water depth of the contracted section, and q is the flow rate per single width.

[0067] From the above description, it can be seen that the flow types of the sluice are classified and calculated, so that the calculation formula can be quickly called to calculate the new water inflow into the current enclosure according to the water level conditions before and after the sluice, ensuring that the water replacement rate can be obtained in real time and accurately.

[0068] Please refer to Figure 2 A terminal for calculating water replacement rate of a plain river network based on remote sensing images comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the following is achieved:

[0069] Step S1, establishing a water surface area-water level fitting relationship between the water surface area of ​​the water system in the plain river network enclosure and the water level of the water system through remote sensing images;

[0070] Step S2, calculating the first water volume from the river water body between the lowest water level of the plain river network enclosed area water system and the first water system water level according to the difference method and the water surface area-water level fitting relationship;

[0071] Step S3, calculating the second water volume below the lowest water level of the plain river network enclosed area water system by using the volume generalization formula method, and adding the first water volume and the second water volume to obtain the total water volume of the enclosed area water system corresponding to the first water system water level;

[0072] Step S4, repeating the above steps S2 and S3 until the total water volume of the water system in the plain river network enclosed area corresponding to the water level of each water system in the plain river network enclosed area is obtained, and a water level-water volume fitting relationship and a water surface area-water volume fitting relationship of the plain river network enclosed area water system are established;

[0073] Step S5, obtaining the new water inflow into the current enclosed area water system of the plain river network at the current moment, and obtaining the total water volume of the current enclosed area water system at the current moment from the water level-water volume fitting relationship according to the current water level of the current water system monitored by the key control point of the current water system at the current moment, or obtaining the total water volume of the current enclosed area water system at the current moment from the water surface area-water volume fitting relationship according to the water surface area of ​​the current water system at the current moment, and dividing the new water inflow into the current enclosed area at the current moment by the total water volume of the current enclosed area water system to obtain the water volume replacement rate.

[0074] From the above description, we can know that the water surface area-water level fitting relationship between the water surface area and the water level of the plain river network water system is established through remote sensing images, and then the total water volume of the water system in the enclosed area is divided into two parts, one of which is calculated by the difference method, and the other is calculated by the volume generalization formula method, so as to quickly and accurately establish the water level-water volume fitting relationship and the water surface area-water volume fitting relationship of the plain river network water system, thereby avoiding the complex and data-intensive water quality model method, and there is no need to conduct river section analysis on the complex and huge river network. Measurement work; then, by obtaining the current new water inflow into the plain river network enclosed area water system at the current moment, and according to the current water system water level at the current moment from the water level-water volume fitting relationship or according to the current water system water surface area at the current moment from the water surface area-water volume fitting relationship, the total water volume of the current enclosed area water system is obtained, and the water volume replacement rate is obtained in real time. That is, the present invention can obtain the water volume replacement rate in real time, and its accuracy meets the calculation requirements of the water volume quality exchange of the river network water system, so as to timely grasp the water volume scheduling situation of the enclosed area, and has strong practicality.

[0075] Furthermore, the step S1 specifically includes the following steps:

[0076] Through remote sensing images, the water surface area of ​​the plain river network water system at every moment is obtained;

[0077] The weighted average of the water level data of all water level stations in the water system of the plain river network enclosed area at each corresponding moment is used as the water system water level of the water system of the plain river network enclosed area at each moment;

[0078] A water surface area-water level fitting relationship is established based on the corresponding relationship between the water surface area and the water level of the water system in the plain river network enclosure at each moment.

[0079] From the above description, it can be seen that since the gradient within the water system of the plain river network enclosed area will not be too large, the weighted average of the water level data of all water level stations in the water system of the plain river network enclosed area is used as the water level of the water system in the enclosed area at each moment. The above water level calculation is also applicable to obtaining the current water system water level at the current moment in step S5, thereby reducing the amount of water level calculation and ensuring the real-time nature of the water replacement rate.

[0080] Furthermore, the step S2 specifically includes the following steps:

[0081] The river water body between the lowest water level of the water system in the plain river network enclosure and the water level of the first water system is divided into multiple layers of layered water bodies, and the water surface areas of the upper and lower layers of each layer of the layered water body are obtained based on the water surface area-water level fitting relationship;

[0082] The water volume of each layer of the layered water body is obtained by multiplying the average water surface area of ​​the upper and lower layers of each layer of the layered water body by the water level difference between adjacent layers, and the water volumes of all the layered water bodies are accumulated to obtain the first water volume.

[0083] From the above description, it can be seen that when the thickness of each layer of the layered water body is small, the layered water body can be approximately regarded as a prism, and the first water volume can be quickly calculated using the formula for calculating the volume of a prism.

[0084] Furthermore, the step S5 specifically includes the following steps when obtaining the current amount of new water flowing into the plain river network enclosed area water system at the current moment:

[0085] The real-time data of the opening degree of the water-passing structure and the water level before and after the water system in the plain river network enclosure are connected, and the flow rate newly flowing into the water system in the plain river network enclosure at the current moment is calculated according to the flow type of the water system in the plain river network enclosure, the opening degree of the water-passing structure, the real-time data of the water level before and after the water system and the hydrodynamic flow formula;

[0086] From the initial moment of water replacement to the current moment of calculating the replacement rate, the flow change process of the water-passing buildings during this period is counted, and the new water inflow of the current enclosure is obtained based on the flow change process.

[0087] From the above description, it can be seen that the flow types of the sluice are classified and calculated, so that the calculation formula can be quickly called to calculate the new water inflow into the current enclosure according to the water level conditions before and after the sluice, ensuring that the water replacement rate can be obtained in real time and accurately.

[0088] Since the plain river network water system is a strip-shaped water body, when new water flows in from the upstream, it will flow along the river channel and then flow out from the downstream outlet instead of staying in the same place. Therefore, the replacement of the river channel water body can be completed by introducing new water bodies, and the water flow route can be adjusted by controlling the opening and closing of water-passing structures on the water system to complete the water body replacement of the corresponding tributaries. Therefore, the present invention uses the amount of water newly entering the water system through the water-passing structures as the amount of new water bodies, and the total water storage at the corresponding time in the water system as the amount of total water bodies, so it is reasonable and feasible to calculate the water replacement rate.

[0089] This embodiment is mainly used to judge the water volume and water quality replacement process in the river network area of ​​the coastal plain. It is not limited by the cross-sectional shape of the river channel and the measured flow data. It can solve the calculation method of the water volume replacement rate change process for many large and small water systems. The specific implementation is detailed in the following embodiments.

[0090] Please refer to Figure 1 , Embodiment 1 of the present invention is:

[0091] A method for calculating water replacement rate of plain river network based on remote sensing images, including:

[0092] Step S1, establishing a water surface area-water level fitting relationship between the water surface area of ​​the water system in the plain river network enclosure and the water level of the water system through remote sensing images;

[0093] Wherein, step S1 specifically includes the following:

[0094] Step S11, obtaining the water surface area of ​​the plain river network at each moment through remote sensing images;

[0095] In this embodiment, the images acquired by the high-resolution optical remote sensing satellite can be processed by geometric correction, orthorectification, radiation calibration, atmospheric correction, information enhancement and image classification to extract the water body boundary. Identify the water surface area A1 at time t, the water surface area A2 at time t+1, ..., the water surface area A at time t+n (n∈N) n .

[0096] Step S12, taking the weighted average of the water level data of all water level stations in the plain river network enclosed area water system at each corresponding moment as the water level of the plain river network enclosed area water system at each moment;

[0097] In this embodiment, the water level monitoring and transmission system is used to obtain the water level data of all water level stations (m) in the water system of the enclosed area at time t. Since the river gradient in the coastal plain enclosed area is not too large, the weighted average of the m water level data is used. As the water level of the water system in the enclosure at time t, and set the key control point of the current water system, so that the monitored water level of the key control point is used as the representative value of the subsequent water level. Similarly, the average water level of the water system in the enclosure at time t+1, t+2, ..., t+n is obtained

[0098] Step S13: establishing a water surface area-water level fitting relationship based on the corresponding relationship between the water surface area of ​​the plain river network enclosure water system and the water level of the water system at each moment.

[0099] In this embodiment, the water surface area A at time t, t+1, t+2, ..., t+n is i and average water level One-to-one correspondence is used to establish the scatter plot fitting correlation relationship. (i=1, 2, ..., n+1).

[0100]

[0101] Step S2, calculating the first water volume of the river water body between the lowest water level of the plain river network enclosed area water system and the first water system water level according to the difference method and the water surface area-water level fitting relationship;

[0102] Wherein, step S2 specifically includes the following steps:

[0103] Step S21, dividing the river water body between the lowest water level of the plain river network enclosure water system and the first water system water level into multiple layers of layered water bodies, and obtaining the upper and lower water surface areas of each layer of layered water body based on the water surface area-water level fitting relationship;

[0104] In this embodiment, from the lowest water level To the highest water level The water body is divided into j thin layers of water with a small thickness of d. The corresponding water level of the lower surface of the kth layer of water is The water level corresponding to the upper surface is The corresponding surface area A is obtained by using the water surface area-water level fitting relationship of the enclosed water system obtained in step S1 k and A k+1 .

[0105] Step S22, multiplying the average water surface area of ​​the upper and lower layers of each layered water body by the water level difference between adjacent layers to obtain the water volume of each layered water body, and accumulating the water volumes of all layered water bodies to obtain the first water volume.

[0106] In this embodiment, since the thickness d of the water layer is very small, the water layer can be approximately regarded as a prism, and the volume V of the kth water layer is k for:

[0107]

[0108] Step S3, calculating the second water volume below the lowest water level of the plain river network enclosed area water system using the volume generalization formula method, adding the first water volume and the second water volume to obtain the total water volume of the enclosed area water system corresponding to the first water system water level;

[0109] Among them, in step S3, the second water volume below the lowest water level of the plain river network enclosed area water system is calculated by using the volume generalization formula method, which specifically includes the following steps:

[0110] Obtain the cross-sectional shape of the river channel of the plain river network enclosed area water system. If the cross-sectional shape of the river channel is approximately a triangle, use the triangular prism formula method to calculate the second water volume below the lowest water level of the plain river network enclosed area water system. If the cross-sectional shape of the river channel is approximately a semicircular section, use the semi-cylinder formula method to calculate the second water volume.

[0111] In this embodiment, because there is no remote sensing image between the lowest water level and the bottom of the river channel, and the lowest water level of the coastal plain river network usually does not correspond to a high water depth, the river channel section below the lowest water level is generalized into a triangular section (deep and narrow) or a semicircular section (wide and shallow), and this part of the water body is generalized into a triangular prism (deep and narrow) or a semi-cylinder (wide and shallow). The corresponding water surface area is A0, and the corresponding water depth is h0, then the volume of this part of the water is:

[0112]

[0113] or

[0114] Then add the volumes of the two parts of water to get the total water volume of the enclosed area water system at the first water system level;

[0115] In this embodiment, different average water levels are obtained. The corresponding total water volume V of the water system in the enclosed area, the relationship between the total water volume of the water system in the enclosed area and the water level is established as follows:

[0116]

[0117]

[0118] Where L is the current average water level The number of layers.

[0119] Step S4, repeating the above steps S2 and S3 until the total water volume of the water system in the plain river network enclosed area corresponding to the water level of each water system is obtained, and the water level-water volume fitting relationship and the water surface area-water volume fitting relationship of the water system in the plain river network enclosed area are established;

[0120] After obtaining the water level-water volume fitting relationship, the water surface area-water volume fitting relationship can be obtained according to the water surface area-water level fitting relationship in step S1. In this way, the water level-water volume fitting relationship and the water surface area-water volume fitting relationship are stored in the database, and the water volume can be quickly calculated through the stored fitting relationship when the water volume replacement rate needs to be calculated.

[0121] In addition, the water level-water volume fitting relationship and the water surface area-water volume fitting relationship are not static after being calculated and generated. Steps S1 to S4 are executed in real time to continuously calculate the above fitting relationships, and then they are updated and stored.

[0122] Step S5, obtain the new water inflow into the water system of the plain river network enclosed area at the current moment, and obtain the total water volume of the current enclosed area water system at the current moment from the water level-water volume fitting relationship according to the current water level of the current water system at the current moment, and divide the new water inflow into the current enclosed area at the current moment by the total water volume of the current enclosed area water system to obtain the water replacement rate.

[0123] Wherein, step S5 specifically includes the following steps:

[0124] Step S51, access the real-time data of the opening degree of the water-passing structure and the water level before and after the plain river network enclosure water system, and calculate the flow rate of the new flow into the plain river network enclosure water system at the current moment according to the flow type, the opening degree of the water-passing structure, the real-time data of the water level before and after the plain river network enclosure water system and the hydrodynamic flow formula;

[0125] Among them, water-passing structures include sluice gates, water pumps, etc. Therefore, the opening degree of the water-passing structures corresponds to the opening degree of the sluice gates.

[0126] Step S52: from the initial moment of starting water replacement to the current moment of calculating the replacement rate, the flow change process of the water-passing building during this period is counted, and the new water inflow of the current enclosure is obtained according to the flow change process.

[0127] In this embodiment, the cumulative value of the flow rate newly entering the enclosed area water system is counted. The change process of the flow rate Q flowing into the enclosed area water system in the period T is averaged and multiplied by the period T to obtain the water volume V newly flowing into the enclosed area water system in this period x , where the flow change process is that the inflow is positive and the outflow is negative.

[0128] Step S53, and obtain the total water volume of the current water system in the current enclosure at the current moment from the water level-water volume fitting relationship according to the current water system water level monitored by the current water system key control point at the current moment, or obtain the total water volume of the current water system in the current enclosure at the current moment from the water surface area-water volume fitting relationship according to the current water system water surface area at the current moment. Read the average water level of the enclosure water system at the end of the calculation period T, and use the water level-water volume fitting relationship obtained in step S4 to calculate the total water volume V of the water system in the enclosure at this time.T .

[0129] Step S54, dividing the newly-inflow water volume at different moments by the total water volume at the corresponding moments, and calculating the water volume replacement rate at different moments, so as to obtain the change process of the water volume replacement rate over time.

[0130] Among them, the calculation formula of water replacement rate F is:

[0131]

[0132] In this embodiment, the step S51 calculates the flow rate of the new flow into the plain river network enclosed area water system at the current moment according to the flow type of the plain river network enclosed area water system, the opening of the water-passing structure, the real-time data of the water levels before and after, and the hydrodynamic flow formula, and specifically includes the following steps:

[0133] When the sluice opening e and the water head h in front of the sluice are u The ratio is less than or equal to 0.65 and the water head behind the gate h d Less than the water depth after the jump h c When the flow type of the water system in the plain river network area is free outflow from the gate hole, the flow formula is:

[0134]

[0135] Where Q is the gate flow rate, in m 3 / s; n is the number of gate openings, b is the width of a single gate hole, in m, g is the gravity coefficient, usually 9.8N / kg, and μ is the gate hole flow coefficient, which is expressed as:

[0136]

[0137] In the formula, is the velocity coefficient, which is related to the inflow boundary conditions of the gate hole; ε is the vertical contraction coefficient. For a flat gate, the vertical contraction coefficient ε is related to the relative opening e / h u The polynomial fitting is as follows:

[0138] ε=0.402(e / h u ) 3 -0.255(e / h u ) 2 +0.0985(e / h u )+0.6073;

[0139] Among them, the gate flow coefficient μ can also be calculated using the following empirical formula:

[0140]

[0141] When the sluice opening e and the water head h in front of the sluice are u The ratio is less than or equal to 0.65 and the water head behind the gate h d Greater than or equal to the water depth after the jump h c When the flow type of the water system in the plain river network area is the flooding outflow of the gate hole, the flow formula is:

[0142]

[0143] Where Q is the gate flow rate, n is the number of gate openings, b is the width of a single gate hole, μ is the gate hole flow coefficient, see the above formula, σ h is the flooding coefficient, and its expression is:

[0144]

[0145] α c =(h d -h c ) / (h u -h c );

[0146]

[0147] h z =εe;

[0148] Among them, α c is the undercurrent ratio, h z is the water depth of the contraction section, q is the flow rate per single width, in m 3 / s, that is, the flooding coefficient σ in this embodiment h Through the undercurrent ratio α c Calculate and obtain.

[0149] In step S5, the flow type also includes a broad crest weir outflow. Since the sluice weir type of the plain river network water system is generally a broad crest weir, the broad crest weir outflow formula is used as a representative for calculation, which is as follows:

[0150] When the sluice opening e and the water head h in front of the sluice are u The ratio is greater than 0.65 and the downstream water depth h from the weir top s When the ratio of the total water head H0 at the weir top is less than 0.8, the flow type of the water system in the plain river network area is free overflow of the wide crest weir, and the flow formula is:

[0151]

[0152] When the sluice opening e and the water head h in front of the sluice are u The ratio is greater than 0.65 and the downstream water depth h from the weir top sWhen the ratio to the weir crest water head H0 is greater than or equal to 0.8, the flow type of the water system in the plain river network enclosure area is broad-crested weir submerged overflow, and the flow formula is:

[0153]

[0154] In the formula, Q is the gate discharge, with the unit of m 3 / s; n is the number of orifices of the gate, b is the width of a single gate orifice, with the unit of m, g is the gravity coefficient, usually taking the value of 9.8 N / kg, m is the overflow discharge coefficient, σ c is the side contraction coefficient, and σ s is the submergence coefficient.

[0155] The discharge coefficient m is related to the type of weir. Specifically, it can be determined by referring to the "Hydraulic Calculation Manual". For a broad-crested weir with a bottom sill and a right-angled inlet weir head, when the ratio of the weir height P to the weir crest water head H, P / H ≥ 3, m = 0.32; when 0 < P / H < 3, m is calculated according to the following empirical formula:

[0156]

[0157] Among them, the side contraction coefficient σ c reflects the influence of the pier on the water flow. Specifically, it can be determined by referring to the empirical table of the side contraction coefficient σ c in the "Hydraulic Calculation Manual".

[0158] The submergence coefficient σ s of the broad-crested weir is related to the degree of submergence of the water flow, that is, the value of h s / H0. Specifically, it can be determined by referring to the empirical table of the submergence coefficient σ s in the "Hydraulic Calculation Manual".

[0159] Please refer to Figure 2 For the second embodiment of the present invention:

[0160] A terminal 1 for calculating the water volume replacement rate of a plain river network based on remote sensing images, including a memory 3, a processor 2, and a computer program stored on the memory 3 and executable on the processor 2. When the processor 2 executes the computer program, it implements the steps of the first embodiment above.

[0161] In summary, the present invention provides a method and terminal for calculating the water replacement rate of a plain river network based on remote sensing images. Through remote sensing images, the weighted average of the water level data of all water level stations in the water system of the plain river network enclosed area is used as the water level of the water system in the enclosed area at each moment, thereby establishing a water surface area-water level fitting relationship between the water surface area of ​​the water system in the plain river network enclosed area and the water level of the water system. After that, the total water volume of the water system in the enclosed area is divided into two parts, one of which is calculated according to the difference method and the water surface area-water level fitting relationship to obtain the first water volume, and the other part is calculated using the volume generalization formula method, so as to quickly and accurately establish the water level-water volume fitting relationship and the water surface area-water volume fitting relationship of the water system in the plain river network enclosed area, thereby avoiding A complex water quality model method with high data requirements was developed, and there is no need to conduct river section measurement on the complex and huge river network; then the sluice flow types were classified and calculated, so that the calculation formula can be quickly called to calculate the new water inflow in the current enclosure according to the water level conditions before and after the sluice, and the total water volume of the current enclosure water system is obtained from the water level-water volume fitting relationship according to the current water level of the current water system at the current moment or from the water surface area-water volume fitting relationship according to the current water surface area of ​​the current water system at the current moment, so as to calculate the water volume replacement rate in real time. That is, the present invention can obtain the water volume replacement rate in real time, and its accuracy meets the calculation requirements of the water volume and quality exchange of the river network water system, so as to timely grasp the water volume scheduling situation in the enclosure, and has strong practicality.

[0162] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent transformations made using the contents of the present invention's specification and drawings, or directly or indirectly applied in related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for calculating water replacement rate of plain river network based on remote sensing images, characterized in that: include: Step S1, establishing a water surface area-water level fitting relationship between the water surface area of ​​the water system in the plain river network enclosure and the water level of the water system through remote sensing images; Step S2, calculating the first water volume from the river water body between the lowest water level of the plain river network enclosed area water system and the first water system water level according to the difference method and the water surface area-water level fitting relationship; Step S3, calculating the second water volume below the lowest water level of the plain river network enclosed area water system by using the volume generalization formula method, and adding the first water volume and the second water volume to obtain the total water volume of the enclosed area water system corresponding to the first water system water level; Step S4, repeating the above steps S2 and S3 until the total water volume of the water system in the plain river network enclosed area corresponding to the water level of each water system in the plain river network enclosed area is obtained, and a water level-water volume fitting relationship and a water surface area-water volume fitting relationship of the plain river network enclosed area water system are established; Step S5, obtaining the new water inflow into the current enclosed area water system of the plain river network at the current moment, and obtaining the total water volume of the current enclosed area water system at the current moment from the water level-water volume fitting relationship according to the current water level of the current water system monitored by the key control point of the current water system at the current moment, or obtaining the total water volume of the current enclosed area water system at the current moment from the water surface area-water volume fitting relationship according to the water surface area of ​​the current water system at the current moment, and dividing the new water inflow into the current enclosed area at the current moment by the total water volume of the current enclosed area water system to obtain the water volume replacement rate.

2. The method for calculating water replacement rate of a plain river network based on remote sensing images according to claim 1 is characterized in that: The step S1 specifically includes the following steps: Through remote sensing images, the water surface area of ​​the plain river network water system at every moment is obtained; The weighted average of the water level data of all water level stations in the water system of the plain river network enclosed area at each corresponding moment is used as the water system water level of the water system of the plain river network enclosed area at each moment; A water surface area-water level fitting relationship is established based on the corresponding relationship between the water surface area and the water level of the water system in the plain river network enclosure at each moment.

3. The method for calculating water replacement rate of a plain river network based on remote sensing images according to claim 1 is characterized in that: The step S2 specifically includes the following steps: The river water body between the lowest water level of the water system in the plain river network enclosure and the water level of the first water system is divided into multiple layers of layered water bodies, and the water surface areas of the upper and lower layers of each layer of the layered water body are obtained based on the water surface area-water level fitting relationship; The water volume of each layer of the layered water body is obtained by multiplying the average water surface area of ​​the upper and lower layers of each layer of the layered water body by the water level difference between adjacent layers, and the water volumes of all the layered water bodies are accumulated to obtain the first water volume.

4. The method for calculating water replacement rate of a plain river network based on remote sensing images according to claim 1 is characterized in that: The step S5 of obtaining the current amount of new water flowing into the plain river network enclosed area at the current moment specifically includes the following steps: The real-time data of the opening degree of the water-passing structure and the water level before and after the water system in the plain river network enclosure are connected, and the flow rate newly flowing into the water system in the plain river network enclosure at the current moment is calculated according to the flow type of the water system in the plain river network enclosure, the opening degree of the water-passing structure, the real-time data of the water level before and after the water system and the hydrodynamic flow formula; From the initial moment of water replacement to the current moment of calculating the replacement rate, the flow change process of the water-passing buildings during this period is counted, and the new water inflow of the current enclosure is obtained based on the flow change process.

5. The method for calculating water replacement rate of a plain river network based on remote sensing images according to claim 4 is characterized in that: The step S5 of calculating the flow rate of the new flow into the plain river network enclosed area water system at the current moment according to the flow type of the plain river network enclosed area water system, the opening of the water-passing structure, the real-time data of the front and rear water levels and the hydrodynamic flow formula specifically includes the following steps: When the sluice opening e and the water head h in front of the sluice are u The ratio is less than or equal to 0.65 and the water head behind the gate h d Less than the water depth after the jump h c When the flow type of the water system in the plain river network enclosure is free outflow from the gate hole, the flow formula is: ； In the formula, Q is the gate flow rate, n is the number of gate openings, b is the width of a single gate hole, and μ is the gate hole flow coefficient. The expression is: ； In the formula, φ is the velocity coefficient, ε is the vertical contraction coefficient, and the polynomial fitting is as follows: 。 6. The method for calculating water replacement rate of a plain river network based on remote sensing images according to claim 4 is characterized in that: The step S5 of calculating the flow rate of the new flow into the plain river network enclosed area water system at the current moment according to the flow type of the plain river network enclosed area water system, the opening of the water-passing structure, the real-time data of the front and rear water levels and the hydrodynamic flow formula specifically includes the following steps: When the sluice opening e and the water head h in front of the sluice are u The ratio is less than or equal to 0.65 and the water head behind the gate h d Greater than or equal to the water depth after the jump h c When the flow type of the water system in the plain river network enclosure is sluice hole submerged outflow, the flow formula is: ； In the formula, Q is the gate flow rate, n is the number of gate openings, b is the width of a single gate hole, and μ is the gate hole flow coefficient. The expression is: ； In the formula, φ is the velocity coefficient, ε is the vertical contraction coefficient, and the polynomial fitting is as follows: ； In the formula, σ h is the flooding coefficient, and its expression is: ； ； ； ； In the formula, α c is the undercurrent ratio, h z is the water depth of the contracted section, and q is the flow rate per single width.

7. A terminal for calculating water replacement rate of a plain river network based on remote sensing images, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the following is achieved: Step S1, establishing a water surface area-water level fitting relationship between the water surface area of ​​the water system in the plain river network enclosure and the water level of the water system through remote sensing images; Step S2, calculating the first water volume from the river water body between the lowest water level of the plain river network enclosed area water system and the first water system water level according to the difference method and the water surface area-water level fitting relationship; Step S3, calculating the second water volume below the lowest water level of the plain river network enclosed area water system by using the volume generalization formula method, and adding the first water volume and the second water volume to obtain the total water volume of the enclosed area water system corresponding to the first water system water level; Step S4, repeating the above steps S2 and S3 until the total water volume of the water system in the plain river network enclosed area corresponding to the water level of each water system in the plain river network enclosed area is obtained, and a water level-water volume fitting relationship and a water surface area-water volume fitting relationship of the plain river network enclosed area water system are established; Step S5, obtaining the new water inflow into the current enclosed area water system of the plain river network at the current moment, and obtaining the total water volume of the current enclosed area water system at the current moment from the water level-water volume fitting relationship according to the current water level of the current water system monitored by the key control point of the current water system at the current moment, or obtaining the total water volume of the current enclosed area water system at the current moment from the water surface area-water volume fitting relationship according to the water surface area of ​​the current water system at the current moment, and dividing the new water inflow into the current enclosed area at the current moment by the total water volume of the current enclosed area water system to obtain the water volume replacement rate.

8. The terminal for calculating water replacement rate of a plain river network based on remote sensing images according to claim 7 is characterized in that: The step S1 specifically includes the following steps: Through remote sensing images, the water surface area of ​​the plain river network water system at every moment is obtained; The weighted average of the water level data of all water level stations in the water system of the plain river network enclosed area at each corresponding moment is used as the water system water level of the water system of the plain river network enclosed area at each moment; A water surface area-water level fitting relationship is established based on the corresponding relationship between the water surface area and the water level of the water system in the plain river network enclosure at each moment.

9. The terminal for calculating water replacement rate of a plain river network based on remote sensing images according to claim 7, characterized in that: The step S2 specifically includes the following steps: The river water body between the lowest water level of the water system in the plain river network enclosure and the water level of the first water system is divided into multiple layers of layered water bodies, and the water surface areas of the upper and lower layers of each layer of the layered water body are obtained based on the water surface area-water level fitting relationship; The water volume of each layer of the layered water body is obtained by multiplying the average water surface area of ​​the upper and lower layers of each layer of the layered water body by the water level difference between adjacent layers, and the water volumes of all the layered water bodies are accumulated to obtain the first water volume.

10. The terminal for calculating water replacement rate of a plain river network based on remote sensing images according to claim 7, characterized in that: The step S5 specifically includes the following steps when obtaining the new water inflow into the current enclosed area of ​​the plain river network enclosed area water system at the current moment: The real-time data of the opening degree of the water-passing structure and the water level before and after the water system in the plain river network enclosure are connected, and the flow rate newly flowing into the water system in the plain river network enclosure at the current moment is calculated according to the flow type of the water system in the plain river network enclosure, the opening degree of the water-passing structure, the real-time data of the water level before and after the water system and the hydrodynamic flow formula; From the initial moment of water replacement to the current moment of calculating the replacement rate, the flow change process of the water-passing buildings during this period is counted, and the new water inflow of the current enclosure is obtained based on the flow change process.

Images