Measuring device and measuring method for detecting the amount of siltation in dense suspended matter water

Abstract

The application discloses a kind of in dense suspended solids water probe silt surveying measuring equipment and measuring method, including equipment ontology, through slot, sliding plate, extension plate, collection frame, longitudinal slot, threaded rod, sounder receiver and waterproof sound wave release ware and other key components.By starting motor driving threaded rod rotation, clean up garbage in the left side of waterproof sound wave release ware, then measure water depth and silt thickness by sound wave reflection principle.The novel place of this method is that it not only provides a kind of efficient underwater silt measuring technology, but also realizes the protection of measuring equipment and the friendly treatment to environment through the innovative design of mechanical structure.The implementation of the application provides a new technical scheme for the accurate evaluation of underwater silt, and has important practical application value.

Description

Technical Field

[0001] This invention relates to the field of measuring equipment technology, and in particular to a measuring device and method for detecting sediment volume in water with dense suspended matter. Background Technology

[0002] In the field of underwater sediment detection, traditional measurement techniques mainly rely on two categories of methods: direct measurement and indirect calculation. Direct measurement methods involve using tools such as sounding hammers or sounding rods to determine water depth through physical contact with the seabed. Indirect calculation methods involve acoustic sounding, single-beam and multi-beam echo sounding, which estimate water depth by measuring the propagation time of sound or electromagnetic waves. However, these techniques have limitations when applied to waters with dense suspended matter, as suspended matter interferes with acoustic signals, affecting measurement accuracy. Furthermore, existing technologies are inefficient in collecting and processing sediment, often requiring additional cleanup work, which not only increases costs but also impacts the environment. Summary of the Invention

[0003] The purpose of this invention is to provide a measuring device and method for detecting sediment volume in water with dense suspended matter.

[0004] To achieve the above objectives, the present invention is implemented according to the following technical solution:

[0005] The present invention includes a device body, the inside of which is provided with a through groove, a sliding plate slidably connected inside the through groove, an extension plate movably abutting the bottom of the sliding plate, a collection frame fixedly connected to the bottom of the extension plate, a longitudinal groove inside the device body, a threaded rod rotatably connected inside the longitudinal groove, a trapezoidal plate fixedly connected to the left side of the sliding plate, the trapezoidal plate being threaded onto the outside of the threaded rod, a sonar receiver being provided at the top of the device body, and a waterproof acoustic wave release device being provided at the bottom of the device body, the waterproof acoustic wave release device and the sonar receiver being electrically connected.

[0006] Preferably, the sliding plate has an internal groove, and a hollow plate is slidably connected inside the internal groove. A first locking plate is fixedly connected to the left side of the hollow plate, and the first locking plate is movably engaged inside the right side of the extension plate. A cuboid is slidably connected inside the hollow plate, and a second locking plate is fixedly connected to the bottom of the cuboid, and the second locking plate is movably engaged at the bottom of the inner wall of the internal groove.

[0007] Preferably, a herringbone frame is fixedly connected to the top of the device body, a transparent plate is slidably connected inside the herringbone frame, a rectangular plate is fixedly connected to the left side of the transparent plate, two screws are rotatably connected inside the rectangular plate, and two screw grooves are provided on the left side of the herringbone frame, with both screw grooves threaded onto the outside of the corresponding screws.

[0008] Preferably, a longitudinal plate is fixedly connected inside the hollow plate, a first spring is fixedly connected to the bottom of the longitudinal plate, the bottom end of the first spring is fixedly connected to the top of the cuboid, and a second spring is fixedly connected to the right side of the hollow plate, the right end of the second spring is fixedly connected to the right side of the inner wall of the built-in groove.

[0009] Preferably, a vertical groove is provided on the left side of the inner wall of the through groove, and the right side of the trapezoidal plate is slidably connected inside the vertical groove.

[0010] Preferably, a protective shell is fixedly connected to the top of the device body, a partition is fixedly connected inside the protective shell, a motor is fixedly connected to the bottom of the partition, and the output end of the motor is fixedly connected to the top of the threaded rod.

[0011] Preferably, a right-angle plate is fixedly connected to the top of the cuboid, and the top of the right-angle plate is slidably connected to the top of the sliding plate.

[0012] By starting the motor, the threaded rod rotates, causing the trapezoidal plate to move downwards. This, in turn, causes the sliding plate, extension plate, and collection frame to move downwards, clearing debris from the left side of the waterproof acoustic wave release device. The device then activates the sonar receiver. The sound waves emitted by the device propagate through the water and reflect back when they encounter sediment or the ground. The sonar receiver receives these reflected sound waves and records the time difference of the echo signals. Combined with the speed of sound in the water, the water depth can be calculated. By measuring the water depth multiple times at different locations, the thickness of the sediment at the bottom can be estimated. The volume of the sediment is calculated using data from multiple measuring points.

[0013] The aforementioned measuring device for detecting sediment volume in water with dense suspended matter involves moving a right-angle plate upwards, causing a cuboid to follow suit and move a second clamping plate upwards. This disengages the second clamping plate from the bottom of the inner wall of the built-in groove. Moving the right-angle plate to the right further causes the perforated plate to follow suit, disengaging the first clamping plate from the inner right side of the extension plate. Moving the collection frame downwards further disengages the extension plate from the bottom of the sliding plate. Simultaneously rotating the two screws on both sides causes them to be threaded into their corresponding grooves. Finally, a transparent plate can be moved to the left to adjust the sonar receiver.

[0014] The measurement method of the measuring device for detecting sediment volume in water with dense suspended solids includes the following steps:

[0015] S1: Deploy the device to the target water area, ensuring that the waterproof acoustic emitter and sonar receiver are at an appropriate underwater depth;

[0016] S2: Start the motor inside the device body to drive the threaded rod to rotate, causing the trapezoidal plate to move downwards, clean the debris on the left side of the waterproof acoustic wave release device, and adjust the transparent plate inside the U-shaped frame to ensure that the sonar receiver is not blocked so as to accurately receive the acoustic wave signal.

[0017] S3: Activate the waterproof acoustic wave emitter to emit an acoustic wave signal. The acoustic wave signal propagates in the water and is reflected back after encountering underwater sediment or the ground. The sonar receiver receives the reflected acoustic wave signal and records the time difference of the echo signal.

[0018] S4: Combine the speed of sound in water and use the time difference to calculate the water depth. Repeat step SS above at different locations to collect multiple water depth data and estimate the thickness of the bottom sediment.

[0019] S5: Using data from multiple measuring points, the volume of silt is calculated through a mathematical model; the volume of silt can be estimated using volume data.

[0020] S6: Operate the right-angle plate to move the cuboid upwards, releasing the engagement between the second clamping plate and the bottom of the inner wall of the built-in groove; move the right-angle plate to the right, moving the hollow plate to the right, releasing the engagement between the first clamping plate and the inside of the right side of the extension plate; move the collection frame downwards to release the contact between the extension plate and the bottom of the sliding plate; rotate the screw to make the screw and the screw groove form a threaded connection; move the transparent plate to the left to adjust the sonar receiver.

[0021] S7: Record all measurement data, including water depth, silt thickness, and volume estimation results; analyze the data to assess the distribution and volume of silt, providing a basis for subsequent cleanup work.

[0022] The beneficial effects of this invention are:

[0023] This invention relates to a measuring device and method for detecting sediment volume in water with dense suspended matter. Compared with existing technologies, this invention combines acoustic detection technology and a mechanical cleaning device to effectively remove suspended matter along the measurement path without affecting the acoustic signal, thereby improving the measurement accuracy of water depth and sediment thickness. The structure is rationally designed, achieving waterproof protection for the sonar receiver through the cooperation of a screw, screw groove, and transparent plate. Simultaneously, the cooperation of a first clamping plate, a second clamping plate, an extension plate, a perforated plate, and a right-angle plate enables the collection of suspended matter and the installation and disassembly of the collection frame, significantly improving the device's working efficiency. While improving efficiency, this invention also considers environmental protection; the collection frame design effectively collects suspended matter during the cleaning process, reducing secondary pollution to the water body. This invention provides accurate data support for the management and maintenance of waterways such as reservoirs, waterways, and ports, facilitating more effective sediment removal, waterway dredging, and environmental monitoring. Attached Figure Description

[0024] Figure 1 This is a three-dimensional structural diagram of the present invention;

[0025] Figure 2 This is a cross-sectional structural diagram of the present invention;

[0026] Figure 3 for Figure 2 A magnified view of part A in the middle;

[0027] Figure 4 for Figure 2 A magnified view of part B in the middle section.

[0028] In the diagram: 1. Equipment body; 2. Through slot; 3. Protective shell; 4. U-shaped frame; 5. Transparent plate; 6. Sonar receiver; 7. Partition plate; 8. Motor; 9. Threaded rod; 10. Vertical slot; 11. Collection frame; 12. Waterproof acoustic wave release device; 13. Sliding plate; 14. Extension plate; 15. Internal slot; 16. First clamping plate; 17. Longitudinal plate; 18. Cuboid; 19. Second clamping plate; 20. Right-angle plate; 21. Hollowed-out plate; 22. First spring; 23. Second spring; 24. Rectangular plate; 25. Screw; 26. Screw groove; 27. Trapezoidal plate. Detailed Implementation

[0029] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. The illustrative embodiments and descriptions herein are used to explain the present invention, but are not intended to limit the present invention.

[0030] Reference Figure 1-4A measuring device for detecting sediment volume in water with dense suspended matter includes: a device body 1, a through groove 2 inside the device body 1, a sliding plate 13 slidably connected inside the through groove 2, an extension plate 14 movably abutting the bottom of the sliding plate 13, a collection frame 11 fixedly connected to the bottom of the extension plate 14, a longitudinal groove inside the device body 1, a threaded rod 9 rotatably connected inside the longitudinal groove, a trapezoidal plate 27 fixedly connected to the left side of the sliding plate 13, the trapezoidal plate 27 being threadedly sleeved on the outside of the threaded rod 9, a sonar receiver 6 at the top of the device body 1, and a waterproof acoustic wave release device 12 at the bottom of the device body 1, the waterproof acoustic wave release device 12 and the sonar receiver 6 being electrically connected.

[0031] In this embodiment, the sliding plate 13 has an internal groove 15, and a hollow plate 21 is slidably connected inside the internal groove 15. A first locking plate 16 is fixedly connected to the left side of the hollow plate 21. The first locking plate 16 is movably locked inside the right side of the extension plate 14. A cuboid 18 is slidably connected inside the hollow plate 21. A second locking plate 19 is fixedly connected to the bottom of the cuboid 18. The second locking plate 19 is movably locked to the bottom of the inner wall of the internal groove 15, thus realizing the installation and disassembly function of the collection frame 11.

[0032] In this embodiment, a U-shaped frame 4 is fixedly connected to the top of the device body 1. A transparent plate 5 is slidably connected inside the U-shaped frame 4. A rectangular plate 24 is fixedly connected to the left side of the transparent plate 5. Two screws 25 are rotatably connected inside the rectangular plate 24. Two screw grooves 26 are provided on the left side of the U-shaped frame 4. Both screw grooves 26 are threaded onto the outside of the corresponding screws 25. A right-angle plate 20 is fixedly connected to the top of the cuboid 18. The top of the right-angle plate 20 is slidably connected to the top of the sliding plate 13, thus realizing the waterproof protection function for the sonar receiver 6.

[0033] In this embodiment, a longitudinal plate 17 is fixedly connected inside the hollow plate 21, a first spring 22 is fixedly connected to the bottom of the longitudinal plate 17, the bottom end of the first spring 22 is fixedly connected to the top of the cuboid 18, a second spring 23 is fixedly connected to the right side of the hollow plate 21, and the right end of the second spring 23 is fixedly connected to the right side of the inner wall of the built-in groove 15, thereby realizing the reset function of the hollow plate 21.

[0034] In this embodiment, a vertical groove 10 is provided on the left side of the inner wall of the through groove 2, and the right side of the trapezoidal plate 27 is slidably connected inside the vertical groove 10. A protective shell 3 is fixedly connected to the top of the device body 1, a partition 7 is fixedly connected inside the protective shell 3, a motor 8 is fixedly connected to the bottom of the partition 7, and the output end of the motor 8 is fixedly connected to the top of the threaded rod 9, thereby realizing the power drive function of the threaded rod 9.

[0035] In this embodiment, during use, the starting motor 8 drives the threaded rod 9 to rotate, which in turn causes the trapezoidal plate 27 to move downwards. This causes the sliding plate 13, extension plate 14, and collection frame 11 to move downwards as well, further clearing the debris on the left side of the waterproof acoustic wave release device 12. The waterproof acoustic wave release device 12 and sonar receiver 6 are then activated. The sound waves emitted by the waterproof acoustic wave release device 12 propagate through the water and are reflected back when they encounter sediment or the ground. The sonar receiver 6 receives the reflected sound waves and records the time difference of the echo signal. Combined with the speed of sound in the water, the water depth can be calculated. Furthermore, by measuring the water depth multiple times at different locations, the thickness of the sediment at the bottom can be estimated. The volume of sediment is calculated using data from multiple measuring points. Moving the right-angle plate 20 upwards causes the cuboid 18 to move upwards as well, further causing the second clamping plate 19 to move upwards, thus disengaging the second clamping plate 19 from the bottom of the inner wall of the built-in groove 15. Moving the right-angle plate 20 to the right causes the perforated plate 21 to move to the right, thereby disengaging the first clamping plate 16 from the right side interior of the extension plate 14. Moving the collection frame 11 downwards further disengages the extension plate 14 from the bottom of the sliding plate 13. In addition to the contact relationship, the two screws 25 on both sides are rotated simultaneously to make the screws 25 on both sides and the corresponding screw grooves 26 extrude a threaded relationship. The transparent plate 5 can be moved to the left to adjust the sonar receiver 6. The cooperation of the screws 25, screw grooves 26 and transparent plate 5 realizes the waterproof protection function of the sonar receiver 6. The cooperation of the first clamping plate 16, the second clamping plate 19, the extension plate 14, the hollow plate 21 and the right angle plate 20 realizes the functions of collecting suspended objects and installing and disassembling the collection frame 11, thereby improving the working efficiency of the device.

[0036] The measurement method of the measuring device for detecting sediment volume in water with dense suspended solids includes the following steps:

[0037] S1: Deploy the device body 1 to the target water area, ensuring that the waterproof acoustic wave emitter 12 and the sonar receiver 6 are at an appropriate underwater depth;

[0038] S2: Start the motor 8 inside the main body of the device 1, drive the threaded rod 9 to rotate, so that the trapezoidal plate 27 moves downward, clean the debris on the left side of the waterproof acoustic wave release device 12, adjust the transparent plate 5 inside the circular frame 4 to ensure that the sonar receiver 6 is not blocked so as to accurately receive the acoustic wave signal.

[0039] S3: Activate the waterproof acoustic wave emitter 12 to emit an acoustic wave signal. The acoustic wave signal propagates in the water and is reflected back after encountering underwater sediment or the ground. The sonar receiver 6 receives the reflected acoustic wave signal and records the time difference of the echo signal.

[0040] S4: Combine the speed of sound in water and use the time difference to calculate the water depth. Repeat steps S1-S3 at different locations to collect multiple water depth data and estimate the thickness of the bottom sediment.

[0041] 10. The method for calculating water depth is as follows:

[0042]

[0043] Where: h: water depth; c: speed of sound in water, which depends on water temperature and salinity; t: time difference between sound wave transmission and reception.

[0044] The speed of sound is calculated as follows:

[0045] c = 1410 + 4.6 * T

[0046] Wherein: T is the water temperature;

[0047] The thickness of the sediment is calculated using the following formula:

[0048] h s =h1-h2

[0049] Where: h s : Silt thickness, h1: Initial water depth, h2: Subsequent water depth measurements;

[0050] The volume of sediment is calculated using the following formula:

[0051] V = A * h s

[0052] Where: V: volume of sediment; A: area of ​​the expected region;

[0053] The estimated area is calculated as follows:

[0054]

[0055] Where: b1 and b2: the widths of the two boundaries of the siltation area;

[0056] S5: Using data from multiple measuring points, the volume of silt is calculated through a mathematical model; the volume of silt can be estimated using volume data.

[0057] S6: Operate the right-angle plate 20 to move the cuboid 18 upward, releasing the engagement between the second clamping plate 19 and the bottom of the inner wall of the built-in groove 15; move the right-angle plate 20 to the right, moving the hollow plate 21 to the right, releasing the engagement between the first clamping plate 16 and the inside of the right side of the extension plate 14; move the collection frame 11 downward, releasing the abutment between the extension plate 14 and the bottom of the sliding plate 13; rotate the screw 25 to make the screw 25 and the screw groove 26 extrude a threaded relationship; move the transparent plate 5 to the left to adjust the sonar receiver 6.

[0058] S7: Record all measurement data, including water depth, silt thickness, and volume estimation results; analyze the data to assess the distribution and volume of silt, providing a basis for subsequent cleanup work.

[0059] Example: Measurement of reservoir silt

[0060] This invention requires measuring the siltation of a reservoir. The water temperature in the reservoir is 20°C. Two measurement points, A and B, are selected to estimate the thickness and volume of the silt.

[0061] Implementation steps:

[0062] Step 1: Equipment preparation and deployment: Deploy the equipment body 1 in the reservoir, ensuring that the waterproof acoustic wave emitter 12 and the sonar receiver 6 are located at an appropriate underwater depth.

[0063] Step 2: Acoustic Wave Detection and Data Collection: Activate the waterproof acoustic wave emitter 12 to emit an acoustic wave signal. The sonar receiver 6 receives the reflected acoustic wave signal and records the time difference of the echo signal.

[0064] Step 3: Water depth calculation: At measurement point A, the time difference between the sound wave transmission and reception is 0.02 seconds.

[0065] The speed of sound is calculated using the formula c = 1410 + 4.6 * T: c = 1410 + 4.6 * 20 = 1470 m / s.

[0066] According to the formula Calculate water depth:

[0067] Step 4: Estimate the thickness of the sediment: Assume that the initial water depth at measurement point A is 15 meters and the current water depth is 14.7 meters.

[0068] According to formula h s =h1-h2 Calculate the thickness of the sediment: h s =15-14.7=0.3 meters.

[0069] Step 5: Estimate the volume of silt: Assume the width of the siltation area is 100 meters and the length is 200 meters, that is, the area A = 100 * 200 = 20,000 square meters.

[0070] According to the formula V=A*h s Calculate the volume of the silt: V = 20000 * 0.3 = 6000 cubic meters.

[0071] Step 6: Repeat the measurement: Repeat steps 2 to 5 at measurement point B to obtain the water depth and sediment thickness.

[0072] Step 7: Data Recording and Analysis: Record the water depth, silt thickness, and volume estimation results at measurement points A and B. Analyze the data to assess the distribution and volume of the silt, providing a basis for subsequent cleanup work.

[0073] Equipment recycling and maintenance: After the measurement is completed, the equipment body 1 is recycled and necessary cleaning and maintenance are carried out.

[0074] The above embodiments enable the estimation of the thickness and volume of silt deposits in specific areas of a reservoir. This embodiment demonstrates how to utilize acoustic detection technology combined with mathematical models to assess underwater siltation, providing scientific data support for reservoir management and maintenance.

[0075] The technical solutions of the present invention are not limited to the specific embodiments described above. Any technical modifications made in accordance with the technical solutions of the present invention fall within the protection scope of the present invention.

Claims

1. A measuring device for detecting sediment volume in water with dense suspended solids, characterized in that, include: The device body (1) has a through groove (2) inside, a sliding plate (13) is slidably connected inside the through groove (2), an extension plate (14) is movably abutted at the bottom of the sliding plate (13), a collection frame (11) is fixedly connected at the bottom of the extension plate (14), a longitudinal groove is provided inside the device body (1), a threaded rod (9) is rotatably connected inside the longitudinal groove, a trapezoidal plate (27) is fixedly connected to the left side of the sliding plate (13), the trapezoidal plate (27) is threaded onto the outside of the threaded rod (9), a sonar receiver (6) is provided at the top of the device body (1), a waterproof acoustic wave release device (12) is provided at the bottom of the device body (1), and the waterproof acoustic wave release device (12) and the sonar receiver (6) are electrically connected. The sliding plate (13) has an internal groove (15) inside, and a hollow plate (21) is slidably connected inside the internal groove (15). A first locking plate (16) is fixedly connected to the left side of the hollow plate (21), and the first locking plate (16) is movably locked inside the right side of the extension plate (14). A cuboid (18) is slidably connected inside the hollow plate (21), and a second locking plate (19) is fixedly connected to the bottom of the cuboid (18). The second locking plate (19) is movably locked to the bottom of the inner wall of the internal groove (15). A herringbone frame (4) is fixedly connected to the top of the device body (1). A transparent plate (5) is slidably connected inside the herringbone frame (4). A rectangular plate (24) is fixedly connected to the left side of the transparent plate (5). Two screws (25) are rotatably connected inside the rectangular plate (24). Two screw grooves (26) are provided on the left side of the herringbone frame (4). Both screw grooves (26) are threaded onto the outside of the corresponding screws (25). The hollow plate (21) is fixedly connected to a longitudinal plate (17). A first spring (22) is fixedly connected to the bottom of the longitudinal plate (17). The bottom end of the first spring (22) is fixedly connected to the top of the cuboid (18). A second spring (23) is fixedly connected to the right side of the hollow plate (21). The right end of the second spring (23) is fixedly connected to the right side of the inner wall of the built-in groove (15).

2. The measuring device for detecting sediment volume in water with dense suspended matter according to claim 1, characterized in that, A vertical groove (10) is provided on the left side of the inner wall of the through groove (2), and the right side of the trapezoidal plate (27) is slidably connected inside the vertical groove (10).

3. The measuring device for detecting sediment volume in water with dense suspended matter according to claim 1, characterized in that, The top of the device body (1) is fixedly connected to a protective shell (3), the inside of the protective shell (3) is fixedly connected to a partition (7), the bottom of the partition (7) is fixedly connected to a motor (8), and the output end of the motor (8) is fixedly connected to the top of the threaded rod (9).

4. The measuring device for detecting sediment volume in water with dense suspended matter according to claim 2, characterized in that, The top of the cuboid (18) is fixedly connected to a right-angle plate (20), and the top of the right-angle plate (20) is slidably connected to the top of the sliding plate (13).

5. A measurement method for a measuring device for detecting sediment volume in densely suspended solids water as described in any one of claims 1-4, characterized in that, Includes the following steps: S1: Deploy the device body (1) to the target water area, ensuring that the waterproof acoustic emitter (12) and sonar receiver (6) are at an appropriate depth underwater; S2: Start the motor (8) inside the main body of the device (1) to drive the threaded rod (9) to rotate, so that the trapezoidal plate (27) moves downward, cleans the garbage on the left side of the waterproof acoustic wave release device (12), adjust the transparent plate (5) inside the circular frame (4) to ensure that the sonar receiver (6) is not blocked so as to accurately receive the acoustic wave signal; S3: Activate the waterproof acoustic wave release device (12) to emit an acoustic wave signal. The acoustic wave signal propagates in the water and is reflected back after encountering bottom sediment or the ground. The sonar receiver (6) receives the reflected acoustic wave signal and records the time difference of the echo signal. S4: Combine the speed of sound in water and use the time difference to calculate the water depth. Repeat steps S1-S3 at different locations to collect multiple water depth data and estimate the thickness of the bottom sediment. S5: Using data from multiple measuring points, the volume of silt is calculated through a mathematical model; the volume of silt can be estimated using volume data. S6: Operate the right-angle plate (20) to move the cuboid (18) upward and release the engagement between the second card plate (19) and the bottom of the inner wall of the built-in groove (15); move the right-angle plate (20) to the right and move the hollow plate (21) to the right to release the engagement between the first card plate (16) and the inside of the right side of the extension plate (14); move the collection frame (11) downward and release the abutment relationship between the extension plate (14) and the bottom of the sliding plate (13); rotate the screw (25) to make the screw (25) and the screw groove (26) extrude the thread relationship; move the transparent plate (5) to the left to adjust the sonar receiver (6); S7: Record all measurement data, including water depth, silt thickness, and volume estimation results; analyze the data to assess the distribution and volume of silt, providing a basis for subsequent cleanup work.

6. The measurement method of the measuring device for detecting sediment volume in densely suspended water according to claim 5, characterized in that: The water depth calculation method in step S4 is as follows: Where: h: water depth; c: speed of sound in water, which depends on water temperature and salinity; t: time difference between sound wave transmission and reception. The speed of sound is calculated as follows: Wherein: T is the water temperature; The thickness of the sediment is calculated using the following formula: Where: h s : Silt thickness, h1: Initial water depth, h2: Subsequent water depth measurements; The volume of sediment is calculated using the following formula: Where: V: volume of sediment; A: area of ​​the expected region; The estimated area is calculated as follows: Where: b1 and b2: the widths of the two boundaries of the siltation area.

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