Method and system for synchronously monitoring bed load and suspended load of river channel

Abstract

The invention provides a method for synchronously monitoring river bed load and suspended load. The method comprises the following steps: (1) an acceleration sensor and an underwater microphone are fixed in a sealed metal aluminum frame, and the metal aluminum frame is flush with a riverbed; a metal basket is arranged at the lower edge of the metal aluminum frame and used for capturing bed load particles and calibrating sensor data; (2) vertically installing a high-frequency ADCP in the center of a riverbed to measure a flow velocity profile; the high-precision turbidity meter is arranged at the upstream of the high-frequency ADCP to record the suspended load concentration; meanwhile, the electronic water level gauge is installed on the bank of the river channel to record water level changes; and (3) analyzing the particle size distribution and transportation amount of the bed load according to the data processing module, and inverting the suspended load flux in combination with ADCP and turbidity meter data. According to the method, the monitoring precision and efficiency are remarkably improved, interference to river ecology is reduced, and reliable data support is provided for river regulation and ecological restoration in a complex environment.

Description

Technical Field

[0001] This invention belongs to the field of water conservancy monitoring technology, specifically relating to a method and system for simultaneous monitoring of bedload and suspended sediment in river channels. Background Technology

[0002] Traditional methods for monitoring river sediment typically rely on distributed, invasive sampling and manual analysis. These methods suffer from several drawbacks: First, they are inefficient, with sampling intervals lasting several hours or even longer, making it difficult to capture the dynamic changes of short-term, high-intensity sediment transport events. Second, the data exhibits high dispersion, with large intervals between sampling points, making it difficult to comprehensively reflect the spatial distribution characteristics of river sediment transport. Third, they are susceptible to interference, as mechanical sampling equipment easily interferes with water flow and sediment movement, affecting the accuracy of monitoring results. Finally, they are insufficient for complex environments; during short-term, high-intensity sediment transport events such as heavy rain and snowmelt, traditional methods struggle to simultaneously capture the dynamic changes in bedload impact load and suspended sediment concentration, often oversimplifying the impact of water level fluctuations on the sediment transport process, thus increasing uncertainty.

[0003] Therefore, finding a convenient and efficient way to address the aforementioned shortcomings is urgently needed in this field. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a method for simultaneous monitoring of bedload and suspended sediment in river channels, the method comprising the following steps: (1) A bedload module is constructed using an accelerometer and an underwater microphone; the accelerometer and the underwater microphone are fixed in a sealed aluminum frame and the aluminum frame is installed flush with the riverbed; a metal basket is set at the lower edge of the aluminum frame to capture bedload particles and calibrate sensor data; (2) A suspended sediment module is constructed using a high-frequency ADCP, a high-precision turbidity meter, and an electronic water level meter; the high-frequency ADCP is vertically installed in the center of the riverbed to measure the flow velocity profile; the high-precision turbidity meter is installed upstream of the high-frequency ADCP to record the suspended sediment concentration; at the same time, the electronic water level meter is installed on the riverbank to record water level changes. (3) Align the data collected by the aforementioned sensors with a high-precision synchronous clock, and analyze the particle size distribution and transport amount of the bedload according to formula (1) and formula (2) based on the data processing module, and invert the suspended mass flux by combining ADCP and turbidimeter data; The particle size of the bedload is calculated according to formula (1), and the mass of the bedload is calculated according to formula (2). (1) (2) In the formula, This represents the median particle size, in mm. M The mass of the particles is expressed in grams. A The amplitude is measured in mm. f The vibration frequency is expressed in Hz.

[0005] Suspended mass flux can be calculated using equation (3); (3) In the formula, W This represents the annual input volume, expressed in kg. A The cross-sectional area of ​​the river is expressed in m². 2 ; The instantaneous flow velocity is expressed in m / s. This represents the instantaneous concentration of the suspended solids, expressed in mg / L. T The total time in a year is expressed in seconds (s).

[0006] Specifically, the triaxial accelerometer records the 0.1-100N impact force signal of bedload particles at a sampling rate of ≥10kHz, with a bandwidth covering 0.17~100Hz.

[0007] Specifically, the triaxial accelerometer is configured with four ranges: acceleration 20 m / s², velocity 0.6 m / s, displacement 500 mm, and 0-p value.

[0008] Specifically, the underwater microphone synchronously collects particle collision sound wave signals in the range of 10Hz-20kHz, while sharing a 1000kΩ load resistor with the triaxial accelerometer.

[0009] Specifically, the high-precision synchronous clock includes a high-precision real-time clock source and a clock synchronization unit.

[0010] Specifically, the surface of the aluminum frame is treated with micro-bumps to enhance the signal-to-noise ratio of the collision signal of the propagating particles.

[0011] Specifically, the high-precision synchronization clock is synchronized via a satellite clock source or the IEEE 1588v2 network protocol, ultimately achieving a system-wide time synchronization accuracy of ≤1ms.

[0012] Specifically, the high-precision turbidimeter has a measurement resolution of 0.1 NTU.

[0013] Specifically, the time synchronization error between the bedload monitoring module and the suspended sediment monitoring module is ≤0.1 seconds, and the cross-sectional coverage rate is over 90%.

[0014] A system for simultaneous monitoring of bedload and suspended sediment in river channels, the system comprising the aforementioned bedload module, suspended sediment module, high-precision synchronization clock, and data processing module; the components in each module are arranged and operated in the aforementioned manner.

[0015] Beneficial effects of this invention: This invention achieves a breakthrough through multimodal sensor fusion technology. It employs a non-invasive, high-precision sensor array (such as accelerometers and underwater microphones) combined with a time-synchronization algorithm to capture comprehensive and continuous sediment transport data in a short time. For example, the high sampling rate and multi-range configuration of the accelerometer accurately record the impact events of bedload particles, while impedance matching design effectively reduces signal interference. Combining a high-frequency ADCP with a high-precision turbidimeter, this non-invasive measurement method not only avoids interference with water flow and sediment movement but also provides accurate velocity data in complex water bodies. By fusing velocity and suspended sediment concentration data, the sediment flux across the entire cross-section is accurately calculated, and short-duration, high-intensity sediment transport events are captured, thus achieving high-precision monitoring of river sediment flux. Through cross-sectional sensor array deployment and a time-synchronization protocol, continuous reconstruction of sediment flux across the entire cross-section at the 0.1-second level can be achieved. This invention not only significantly improves the accuracy and efficiency of monitoring but also reduces interference with the river ecosystem, providing reliable data support for river management and ecological restoration in complex environments. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the field layout; Figure 2 The side view (A) and front view (B) of the transport module are shown. Figure 3 Accelerometer signals (coordinates in logarithmic coordinates) recorded over a specific time interval (1 second for calibration) have a time constant of 0.0001 seconds when the sampling rate is 10 kHz. Figure 4 The image shows the fitting plot of the accelerometer signal and the mass of the bedload (the data are measured values ​​after field calibration). Figure 5 The flow velocity of rivers flowing into the lake as monitored by ADCP for one hydrological year (data online rate 100%). Figure 6 The suspended sediment concentration monitored by a high-precision turbidity meter for one hydrological year (data online rate 100%). Figure 7 The amount of suspended sediment transported in a hydrological year (derived from flow velocity and turbidity data). Detailed Implementation

[0017] The present invention will be specifically described below through embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above-described invention are still within the scope of protection of the present invention.

[0018] Example 1

[0019] 1. Equipment Installation (1) Bedload monitoring module: consisting of an accelerometer and an underwater microphone. The triaxial accelerometer and the underwater microphone are fixed in a sealed aluminum frame. The surface of the aluminum frame is treated with micro-bumps to enhance the signal-to-noise ratio of particle collision signals. The aluminum frame is installed flush with the riverbed, and a metal basket is set at the lower edge of the aluminum frame to capture bedload particles and calibrate sensor data.

[0020] (2) Suspended sediment monitoring module: It consists of a high-frequency ADCP, a high-precision turbidity meter and an electronic water level gauge. The high-frequency ADCP is installed vertically in the center of the riverbed, with a working frequency of 600kHz and a beam opening angle of ≤2°, to measure the flow velocity profile; the high-precision turbidity meter is placed 0.3-0.5 times the water depth below the water surface at a depth of 1.5 times upstream of the ADCP to record the suspended sediment concentration; the electronic water level gauge is installed on the riverbank to record water level changes.

[0021] (3) Time synchronization module: Through the coordination mechanism of GPS / BeiDou dual-mode disciplined clock source and IEEE 1588v2 network protocol, carrier phase level clock locking is achieved when the satellite signal is valid. When the lock is lost, it automatically switches to PTP master clock mode and optimizes the clock path according to the BMCA algorithm. Finally, it ensures that the time synchronization error of the whole system is ≤1ms.

[0022] 2. Data Acquisition and Processing (1) Bedload monitoring: Accelerometers record the impact force signal (0.1-100N) of bedload particles at a sampling rate of ≥10kHz, with a bandwidth of 0.17~100Hz; underwater microphones simultaneously collect particle collision sound wave signals in the range of 10Hz-20kHz.

[0023] (2) Suspended sediment monitoring: High-frequency ADCP is used to measure the flow velocity profile, a high-precision turbidity meter is used to record the suspended sediment concentration, and an electronic water level meter is used to record water level changes.

[0024] (3) Data fusion: All sensor data are aligned through the time synchronization module, and the particle size distribution and transport amount of bedload are analyzed by the impact force-sound wave feature matching algorithm. The suspended mass flux is inverted by combining ADCP and turbidimeter data.

[0025] The particle size of the bedload is calculated according to formula (1), and the mass of the bedload is calculated according to formula (2). (1) (2) In the formula, This represents the median particle size, in mm. M The mass of the particles is expressed in grams. A The amplitude is measured in mm. f The vibration frequency is expressed in Hz.

[0026] Suspended mass flux is calculated using equation (3); (3) In the formula, W This represents the annual input volume, expressed in kg. A The cross-sectional area of ​​the river is expressed in m². 2 ; The instantaneous flow velocity is expressed in m / s. This represents the instantaneous concentration of the suspended solids, expressed in mg / L. T The total time in a year is expressed in seconds (s).

[0027] 3. System Operation and Maintenance The system is solar-powered with a battery pack capacity of ≥200Ah, supporting 7 days of continuous operation even in cloudy or rainy weather. The distance between the data recording device and each sensor is ≤10m, and the protection level reaches IP68, ensuring stable operation of the equipment in the field. Real-time data from all devices is transmitted to the shore-based recording device via a LoRa wireless network, facilitating remote monitoring and data retrieval.

[0028] This embodiment was successfully applied to the monitoring of sediment entering Arrow Bamboo Lake in Jiuzhaigou. As an important heritage site in Jiuzhaigou, Arrow Bamboo Lake suffered extensive landslides and exposure due to the "8.8 Jiuzhaigou Earthquake," resulting in severe soil erosion. Under short-term, high-intensity events such as torrential rains and snowmelt, the lake's waters easily become turbid, leading to a large influx of sediment. This not only accelerates the lake's marshland formation but also poses a serious challenge to the health of the lake's ecosystem and the protection of its heritage. However, under such complex environmental conditions, traditional monitoring methods struggle to achieve simultaneous and continuous monitoring of bedload and suspended sediment. This embodiment was successfully applied in the river channels flowing into Arrow Bamboo Lake from June 2023 to June 2024. The core results are as follows: Bedload monitoring: The system recorded impact events of bedload particles using an accelerometer and successfully analyzed the mass distribution and transport amount of the bedload particles. A strong linear relationship (R²=0.9666) was observed between the accelerometer signal and the bedload particle mass, indicating that using the sensor signal to predict bedload transport has high accuracy.

[0029] Suspended sediment monitoring: The real-time data online rate of ADCP and high-precision turbidimeter reached 100%, enabling continuous monitoring of suspended sediment concentration and flow velocity profiles. Through data fusion algorithms, the annual suspended sediment flux into Jianzhuhai Lake was successfully deduced, and the seasonal variation pattern of sediment entering the lake was analyzed, providing a scientific basis for assessing the dynamic changes of lake sediment.

[0030] System stability: The system operates stably in complex field environments. The solar power system supported normal operation for 7 days under continuous rainy weather and underwent a full year of maintenance-free trial operation. The data recording device has an IP68 protection rating, ensuring the reliability of the equipment in high humidity and high sediment environments.

Claims

1. A method for simultaneous monitoring of bedload and suspended sediment in river channels, characterized in that, The method includes the following steps: (1) A bedload module is constructed using an accelerometer and an underwater microphone; the accelerometer and the underwater microphone are fixed in a sealed aluminum frame and the aluminum frame is installed flush with the riverbed; a metal basket is set at the lower edge of the aluminum frame to capture bedload particles and calibrate sensor data; (2) A suspended sediment module is constructed using a high-frequency ADCP, a high-precision turbidity meter, and an electronic water level meter; the high-frequency ADCP is vertically installed in the center of the riverbed to measure the flow velocity profile; the high-precision turbidity meter is installed upstream of the high-frequency ADCP to record the suspended sediment concentration; at the same time, the electronic water level meter is installed on the riverbank to record water level changes. (3) Align the data collected by the aforementioned sensors with a high-precision synchronous clock, and analyze the particle size distribution and transport amount of the bedload according to formula (1) and formula (2) based on the data processing module, and invert the suspended mass flux by combining ADCP and turbidimeter data; The particle size of the bedload is calculated according to formula (1), and the mass of the bedload is calculated according to formula (2). （1） (2) In the formula, This represents the median particle size, in mm. M The mass of the particles is expressed in grams. A The amplitude is measured in mm. f The vibration frequency is expressed in Hz. Suspended mass flux is calculated using equation (3); (3) In the formula, W This represents the annual input volume, expressed in kg. A The cross-sectional area of ​​the river is expressed in m². 2 ; The instantaneous flow velocity is expressed in m / s. This represents the instantaneous concentration of the suspended solids, expressed in mg / L. T The total time in a year is expressed in seconds (s).

2. The method for simultaneous monitoring of bedload and suspended sediment in river channels according to claim 1, characterized in that, The triaxial accelerometer records the 0.1-100N impact force signal of bedload particles at a sampling rate of ≥10kHz, with a bandwidth covering 0.17~100Hz.

3. The method for simultaneous monitoring of bedload and suspended sediment in river channels according to claim 2, characterized in that, The triaxial accelerometer is configured with four ranges: acceleration 20 m / s², velocity 0.6 m / s, displacement 500 mm, and 0-p value.

4. A method for simultaneous monitoring of bedload and suspended sediment in river channels according to claim 1 or 2, characterized in that, The underwater microphone synchronously acquires particle collision sound wave signals in the range of 10Hz-20kHz, and shares a 1000kΩ load resistor with the triaxial accelerometer.

5. The method for simultaneous monitoring of bedload and suspended sediment in river channels according to claim 1, characterized in that, The high-precision synchronous clock includes a high-precision real-time clock source and a clock synchronization unit.

6. The method for simultaneous monitoring of bedload and suspended sediment in river channels according to claim 1, characterized in that, The surface of the aluminum frame is treated with micro-bumps to enhance the signal-to-noise ratio of the collision signal of the propagating particles.

7. A method for simultaneous monitoring of bedload and suspended sediment in river channels according to claim 1 or 5, characterized in that, The high-precision synchronization clock is synchronized via a satellite clock source or the IEEE 1588v2 network protocol, ultimately achieving a system-wide time synchronization accuracy of ≤1ms.

8. The method for simultaneous monitoring of bedload and suspended sediment in river channels according to claim 1, characterized in that, The high-precision turbidimeter has a measurement resolution of 0.1 NTU.

9. The method for simultaneous monitoring of bedload and suspended sediment in river channels according to claim 1, characterized in that, The time synchronization error between the bedload monitoring module and the suspended sediment monitoring module is ≤0.1 seconds, and the cross-sectional coverage rate is over 90%.

10. A system for simultaneous monitoring of bedload and suspended sediment in river channels, characterized in that, The system includes the mass-moving module, the suspended mass module, the high-precision synchronous clock, and the data processing module as described in claims 1 to 9; the components in each module are arranged in accordance with the manner described in claims 1 to 9, and operate in accordance with the manner described in claims 1 to 7.

Images