A point-to-surface combined litter moisture monitoring system

Abstract

The invention discloses a point-surface combined litter moisture monitoring system, comprising a moisture content sensor, a moisture content radar detector, and an edge perception gateway, wherein a plurality of monitoring points are arranged at intervals in a monitoring area, the moisture content sensor is arranged on the litter surface, the middle of the litter thickness, and the litter grounding surface of each monitoring point, and the moisture content radar detector is arranged at the edge of the monitoring area; the plurality of monitoring points form point moisture content monitoring of the monitoring area; the moisture content radar detector scans the monitoring area to obtain a litter surface echo power change diagram, and obtains a surface moisture content distribution diagram of the monitoring area according to the relative relationship between the echo power and the moisture content, thereby forming surface moisture content monitoring of the monitoring area; the moisture content sensor is wirelessly connected to the edge perception gateway for information exchange, the moisture content radar detector is wiredly connected to the edge perception gateway for information exchange, and the edge perception gateway is connected to a monitoring server.

Description

Technical Field

[0001] The invention relates to a point-and-surface combined litter moisture content monitoring system, which provides effective technical support for the fields of forestry ecology, soil and water conservation, and watershed water cycle. Background Art

[0002] In ecological environment monitoring and forest resource management, litter, as an important part of forest ecosystem, plays an important role in water cycle, soil conservation and biodiversity. However, the monitoring technology of litter moisture content has long faced challenges. Due to the loose structure, high organic matter content and thin thickness of litter, it is difficult for common soil moisture sensors to directly and accurately measure the moisture content of litter. Therefore, the development of efficient and accurate litter moisture content monitoring technology has become an important task in current forest resource management.

[0003] In the process of developing litter water content monitoring technology, previous literature has provided a wealth of theoretical foundations and practical experience. These studies mainly focus on the water-holding and water-conducting mechanism of litter, the impact of litter on hydrological processes, and the monitoring methods of litter water content. For example, the theoretical study of litter water-holding and water-conducting proposed the theory of litter water-holding and water-conducting by conducting experimental research on the water-holding and water-conducting characteristics of the litter layer, providing a theoretical basis for exploring reliable methods for monitoring litter water content. At the same time, previous studies have also explored the water storage mechanism of litter on extreme hydrological processes, providing an important scientific basis for monitoring litter water content.

[0004] In terms of litter moisture monitoring methods, previous literature has proposed a variety of methods, including the application of soilless culture medium moisture sensors, real-time monitoring technology with intelligent algorithms built into front-end sensors, phased array radar scanning technology, etc. These methods have achieved certain results in litter moisture monitoring, but there are still problems such as low monitoring accuracy and difficulty in real-time monitoring. Summary of the invention

[0005] The purpose of the present invention is to provide a litter moisture content monitoring system based on a point-surface combination, which realizes all-round and high-precision monitoring of the litter moisture content by combining point-like and surface-like monitoring methods.

[0006] In order to achieve the above-mentioned purpose, the scheme of the present invention is: a point-surface combined litter moisture monitoring system, comprising a moisture content sensor, a moisture content radar detector, and an edge sensing gateway; a plurality of monitoring points are arranged at intervals in the monitoring area, the moisture content sensor is arranged on the litter surface, the middle of the litter thickness, and the litter ground surface of each monitoring point, and the moisture content radar detector is arranged at the edge of the monitoring area;

[0007] The moisture sensors set at multiple monitoring points are used to monitor the moisture content on the surface of the litter, in the middle of the litter thickness, and on the ground where the litter touches the ground, thus forming point-like moisture content monitoring in the monitoring area.

[0008] The moisture content radar detector scans the monitoring area to obtain the surface echo power change diagram of the litter, and obtains the surface moisture content distribution diagram of the monitoring area based on the relative relationship between the echo power and the moisture content, thus forming the surface moisture content monitoring of the monitoring area;

[0009] The moisture content sensor is wirelessly connected to the edge perception gateway to exchange information, the moisture content radar detector is connected to the edge perception gateway through a wired or 4G / 5G network to exchange information, and the edge perception gateway is connected to the monitoring server.

[0010] A further solution is that the multiple monitoring points are distributed in a grid-like manner within the monitoring area.

[0011] The solution is further that: the water content radar detector is a synthetic aperture radar, and the monitoring area is a synthetic aperture radar scanning imaging area.

[0012] The solution is further: the point moisture content monitoring provides accurate moisture content data of the points in the monitoring area, and the surface moisture content monitoring provides the moisture content distribution of the entire monitoring area. The two are integrated in real time through the edge sensing gateway to form a comprehensive and accurate litter moisture content monitoring result.

[0013] The scheme further includes: the system is provided with a point moisture content monitoring module, a surface moisture content monitoring module, a data acquisition and processing module, and a data transmission module;

[0014] The point moisture content monitoring module is used to receive and record the moisture content data of the moisture content sensor at the monitoring point to form a point distribution of the moisture content in the monitoring area;

[0015] The surface moisture content monitoring module is used to receive and process the data of the moisture content radar detector scanning the monitoring area to form the surface distribution of the moisture content in the monitoring area;

[0016] The data acquisition and processing module is used to perform data cleaning, denoising and smoothing on the moisture content data of the moisture content sensors at the monitoring points received and recorded, and the moisture content radar detector scanning monitoring area data received in the point moisture content monitoring module and the surface moisture content monitoring module. The processed data are integrated into a standard format for subsequent analysis and visualization;

[0017] The data transmission module is used to transmit the point distribution, surface distribution and processed data to a data center or a user terminal in a safe mode.

[0018] The scheme is further as follows: the water content sensor includes an excitation signal source, a dual-ring probe, a detection circuit and a microprocessor. The dual-ring probe includes a transmitting probe and two grounding probes, and the grounding probes are arranged at intervals on both sides of the transmitting probe. The excitation signal source is controlled by the microprocessor to output an oscillation signal of 50MHz to 150MHz through a coaxial cable to the transmitting probe. Signal lines are connected to the detection circuit at both ends of the middle section of the coaxial cable. The output of the detection circuit is connected to the microprocessor. The coaxial cable transmits the high-frequency oscillation signal to the dual-ring probe, and receives the reflected signal and sends it to the microprocessor through the detection circuit.

[0019] The solution is further that: the moisture content sensor uses a standing wave ratio method to determine the moisture content of the litter at the monitoring point, and the standing wave ratio method has a relationship of:

[0020] ;

[0021] in:

[0022] The two ends of the middle section of the coaxial cable, that is , The voltage difference between two points;

[0023] ——The signal amplitude of the signal source output, in V;

[0024] ——The impedance of the double-loop probe and its surrounding medium, in ohms;

[0025] ——Characteristic impedance of coaxial transmission line, in ohms.

[0026] The scheme is further as follows: the surface moisture content distribution map of the monitoring area obtained according to the relative relationship between echo power and moisture content is: the dielectric constant of each point of the echo power change map is calculated according to the echo power and radar parameters, a relationship model between the dielectric constant and moisture content is established through experiments in the laboratory, the dielectric constant of each point of the echo power change map is brought into the relationship model, and the surface moisture content distribution map of the monitoring area is obtained.

[0027] The beneficial effects of the present invention are:

[0028] 1. High-precision monitoring: By combining point and surface monitoring methods, all-round and high-precision monitoring of the moisture content of litter is achieved.

[0029] 2. Real-time monitoring and transmission: The system can monitor the moisture content of litter in real time and quickly transmit the data to the data center to provide support for timely response and decision-making.

[0030] 3. Intelligent processing: The built-in intelligent algorithm and the powerful data processing capabilities of the edge perception gateway enable the system to operate stably in complex environments and automatically perform anomaly detection and data analysis.

[0031] 4. Wide applicability: The present invention is not only applicable to forest ecosystems, but can also be extended to other types of ecosystems such as grasslands, wetlands, etc., and has wide applicability.

[0032] 5. Improve management efficiency: By providing comprehensive and accurate moisture content data, it helps forest resource managers make more scientific decisions and improve management efficiency and protection effects.

[0033] The invention is described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic diagram of the system structure of the present invention;

[0035] Figure 2 It is a schematic diagram of the principle of the water content sensor of the present invention;

[0036] Figure 3 It is a schematic diagram of the water content monitoring process of planar litter based on SAR of the present invention. DETAILED DESCRIPTION

[0037] A point-to-surface combined litter moisture monitoring system, such as Figure 1 , Figure 2 and Figure 3 As shown, the system includes a moisture content sensor 1, a moisture content radar detector 2, and an edge perception gateway 3 (edge ​​intelligent perception terminal monitoring controller); a plurality of monitoring points 401 are arranged at intervals in the monitoring area 4, and the moisture content sensor 1 is respectively arranged on the litter surface, the middle of the litter thickness, and the litter ground surface of each monitoring point, and the moisture content radar detector 2 is arranged at the edge of the monitoring area;

[0038] The moisture sensors 1 set at multiple monitoring points are used to monitor the moisture content of the litter surface, the middle of the litter thickness, and the litter contact surface at the monitoring point 401, so as to form a point-like moisture content monitoring of the monitoring area 4;

[0039] The moisture content radar detector 2 scans the monitoring area 4 to obtain a surface echo power variation diagram of the fallen leaves, and obtains a surface moisture content distribution diagram of the monitoring area according to the relative relationship between the echo power and the moisture content, thereby forming a surface moisture content monitoring of the monitoring area 4;

[0040] The moisture content sensor 1 exchanges information with the edge sensing gateway 3 wirelessly, for example, through a 4G / 5G network connection. The moisture content radar detector 2 exchanges information with the edge sensing gateway 3 through a wired or 4G / 5G network connection. The edge sensing gateway 3 is connected to the monitoring server (or user terminal) 5.

[0041] The point moisture content monitoring provides accurate moisture content data for points in the monitoring area, and the surface moisture content monitoring provides moisture content distribution in the entire monitoring area. The two are integrated in real time through the edge sensing gateway to form comprehensive and accurate litter moisture content monitoring results.

[0042] Among them: when the monitoring area is very large, in order to ensure the reliability of monitoring, the monitoring surface can be divided into multiple monitoring areas 4, and the multiple monitoring points 401 are distributed in a grid-like manner in the monitoring area 4; for example, if the area of ​​the monitoring area 4 is 100m², it is recommended to set at least 9 point sensors (3x3 grid), and the sensor interval is about 10m.

[0043] The water content radar detector 2 is a synthetic aperture radar (SAR), and the monitoring area 4 is an area determined by scanning imaging of the synthetic aperture radar.

[0044] The above can be summarized as follows: Select representative points in the synthetic aperture radar imaging area to install point moisture sensors to form a grid layout. Set up an edge perception gateway at the front end, which accesses the data of each point moisture sensor through the local wireless ad hoc network and accesses the surface data solved by the synthetic aperture radar through Ethernet broadband transmission. The edge gateway performs real-time fusion and online analysis of the point and surface data, and uses the 4G / 5G network to report to the data center of the perception platform in a timely manner.

[0045] The edge sensing gateway integrates a battery and uses solar energy to charge and supplement energy, supporting continuous operation on more than 10 rainy days. The point-to-surface front-end sensing litter moisture monitoring equipment, which consists of a point moisture sensor, a surface moisture distribution detection radar, and an edge sensing gateway, has a self-monitoring, self-networking, self-powered, and self-analyzed operation mode.

[0046] The system is provided with a point moisture content monitoring module, a surface moisture content monitoring module, a data acquisition and processing module, and a data transmission module in the edge sensing gateway 3;

[0047] The point moisture content monitoring module is used to receive and record the moisture content data of the moisture content sensor at the monitoring point to form a point distribution of the moisture content in the monitoring area;

[0048] The surface moisture content monitoring module is used to receive and process the data of the moisture content radar detector scanning the monitoring area to form the surface distribution of the moisture content in the monitoring area;

[0049] The data acquisition and processing module is used to perform data cleaning, denoising and smoothing on the moisture content data of the moisture content sensors at the monitoring points received and recorded, and the moisture content radar detector scanning monitoring area data received in the point moisture content monitoring module and the surface moisture content monitoring module. The processed data are integrated into a standard format for subsequent analysis and visualization;

[0050] The data transmission module is used to transmit the point distribution, surface distribution and the processed data to the data center (monitoring server 5) or the user terminal in a secure mode; it can be safely and quickly transmitted to the data center or the user terminal through the 4G / 5G network or other efficient data transmission protocols.

[0051] Among them: the edge perception gateway 3 receives the original data from point sensors and surface radars; performs preliminary cleaning, denoising and smoothing on the data to improve data quality; merges point data and surface data in real time, and uses the powerful computing power of the edge perception gateway for online analysis; the edge perception gateway can also perform anomaly detection to ensure the accuracy and reliability of the data.

[0052] In the embodiment: the water content sensor includes an excitation signal source 101, a dual-loop probe 102, a detection circuit 103 and a microprocessor 104, the dual-loop probe 102 includes a transmitting probe 102-1 and two grounding probes 102-2, the grounding probes 102-2 are arranged at intervals on both sides of the transmitting probe 102-1, the excitation signal source 101 is controlled by the microprocessor 104 to output an oscillation signal of 50MHz to 150MHz through a coaxial cable 105 to the transmitting probe 102-1, and a signal line is connected to the detection circuit 103 at both ends A and B of a middle section 105-1 of the coaxial cable 105, and the output of the detection circuit 103 is connected to the microprocessor 104, the coaxial cable 105 transmits the high-frequency oscillation signal to the dual-loop probe 102, and receives the reflected signal and sends it to the microprocessor 104 through the detection circuit 103.

[0053] Wherein: the excitation signal source 101, the detection circuit 103 and the microprocessor 104 are arranged in a closed and waterproof shell 106, the transmitting probe 102-1 and the two grounding probes 102-2 in the double-ring probe 102 are fixed on the probe seat 102-3, the double-ring probe 102 is fixed on the surface of the litter, in the middle of the litter thickness and the litter grounding surface through a bracket, and the coaxial cable 105 is led out from the shell to connect the double-ring probe 102.

[0054] The moisture content sensor 1 uses the standing wave ratio method to determine the moisture content of the litter at the monitoring point. Its working principle is as follows: Figure 2As shown. A high-frequency crystal oscillator is used to generate an excitation signal source with a frequency of 50~150MHz. The sinusoidal signal generated by the crystal oscillator is transmitted to the probe along the coaxial cable transmission line. If the probe impedance does not match the transmission line impedance, part of the incident signal will be reflected back to the signal source. The reflected signal and the incident signal are superimposed on the coaxial transmission line to form a standing wave. The voltage amplitude at each point on the transmission line changes. The differential signal between point A and point B in the figure is taken as the sensor output; the standing wave ratio method relationship is:

[0055] ;

[0056] in:

[0057] The two ends of the middle section of the coaxial cable, that is , The voltage difference between two points;

[0058] ——The signal amplitude of the signal source output, in V;

[0059] ——The impedance of the double-loop probe and its surrounding medium, in ohms;

[0060] ——Characteristic impedance of coaxial transmission line, in ohms.

[0061] Coaxial cable characteristic impedance is a fixed value, at the signal amplitude Under the condition of constant, the two ends of the middle section of the coaxial cable, that is, , The voltage difference between two points Only with When the double-ring probe structure is determined, the double-ring probe impedance is a constant value. It is only related to the impedance of the medium around the probe. Through simple calibration, the relationship between impedance and water content of litter can be obtained.

[0062] In the embodiment: the planar moisture content distribution map of the monitoring area obtained according to the relative relationship between echo power and moisture content is: the dielectric constant of each point of the echo power change map is calculated according to the echo power and radar parameters, a relationship model between the dielectric constant and moisture content is established through experiments in the laboratory, the dielectric constant of each point of the echo power change map is brought into the relationship model, and the planar moisture content distribution map of the monitoring area is obtained.

[0063] Among them: the surface moisture distribution monitoring is based on ground-based synthetic aperture radar and differential interferometry technology. Through ground-based synthetic aperture radar technology, high resolution is achieved in the distance direction by pulse compression, and high resolution is achieved in the azimuth direction by beam sharpening, so as to obtain a two-dimensional high-resolution image of the observation area; through differential interferometry technology, the sequence of two-dimensional high-resolution images acquired at different times in the same target area are combined, and the phase difference inversion of each pixel in the image is used to obtain high-precision distance and echo signal intensity information of the measured area. According to the distance and signal intensity, the dielectric constant comparison of the imaging area is further obtained, and the distribution of water content of litter is further obtained after TOPP polynomial data conversion. The principle is the principle of detecting water content of litter by the standing wave method.

[0064] like Figure 3 As shown, the principle of the standing wave method for detecting the moisture content of litter is the change in the dielectric constant of the litter under different moisture content states. Radar waves of a certain frequency will receive different radar reflection signals when detecting litter, and the reflection intensity of the radar signal is related to the distance between the target and the radar and the dielectric constant of the reflector. In this embodiment, the distance of each point is obtained by scanning the litter coverage surface with a synthetic aperture radar, and the dielectric constant distribution of the litter coverage surface is obtained by combining the echo signal intensity of each point.

[0065] About the working process of moisture content radar detector:

[0066] Radar emits electromagnetic waves to the outside world. When the electromagnetic waves hit objects, they are reflected back. The distance to the object can be calculated by the time difference (the speed of light is known).

[0067] Radar cross section is a physical quantity that measures the intensity of the echo generated by a target under the irradiation of radar waves, referred to as RCS. It is the imaginary area of ​​the target, expressed by the projected area of ​​an equivalent reflector that is uniform in all directions. The equivalent reflector has the same echo power as the defined target within a unit solid angle in the receiving direction. In the study of radar cross section, dielectric constant is an important parameter. It determines the target's ability to reflect radar signals.

[0068] The power of radar detection echo is usually described by radar equation. The target echo power Expressed as

[0069]

[0070] in:

[0071] is the radar transmitting power;

[0072] is the radar antenna transmit gain;

[0073] is the radar antenna receiving gain;

[0074] is the radar wavelength, which can be regarded as a constant;

[0075] is the distance between the radar and the target;

[0076] as the goal.

[0077] For a target at a fixed distance, the radar echo power Only targeted impact.

[0078] The dielectric constant of soil is one of the physical parameters that characterizes its dielectric properties or polarization ability, and is expressed as the relative dielectric constant. The relative dielectric constant is equal to the ratio of the real part of the dielectric constant to the dielectric constant of vacuum. The dielectric constants of different soils vary greatly and are closely related to factors such as moisture content, density, temperature, salt content, organic matter, pollutants, and material composition. Among them, soil moisture content is the most sensitive to the dielectric constant, that is, the moisture content of litter will greatly affect the dielectric constant, causing significant changes in the radar echo power of litter with different moisture contents.

[0079] Therefore, by scanning the area with radar and coupling the radar echo signal strength with the distance, the echo of targets at different distances can be calculated. , thus reflecting the change in the water content of litter, that is,

[0080]

[0081] The radar scans the area and obtains a complete radar scanning power diagram. According to the radar equation, the farther the distance, the weaker the echo power. Therefore, it is necessary to remove the influence of distance on the echo power, so as to calculate the reflectivity of the surface at different angles and distances, and finally calculate the dielectric constant of each point.

[0082] Changes in the moisture content of litter are ultimately reflected in changes in the surface dielectric constant of the earth. By comparing the surface dielectric constant data obtained from radar detection in different periods, changes in the moisture content of surface litter can be monitored.

[0083] The following explains the conversion of dielectric constant and calculation of water content distribution.

[0084] 1. Dielectric constant conversion: Based on the radar equation and the received echo signal strength, the dielectric constant of each point is calculated by removing the influence of distance on echo power. The specific methods include:

[0085] 1. Signal strength processing: perform pre-processing such as filtering and denoising on the received echo signal to improve signal quality.

[0086] 2. Distance correction: According to the distance between the radar and the target, the echo power is corrected to eliminate the influence of distance on the echo power.

[0087] 3. Dielectric constant calculation: The dielectric constant of each point is calculated using a specific algorithm using the corrected echo power and radar parameters.

[0088] 2. Calculation of water content distribution: After TOPP polynomial data conversion, the dielectric constant is converted into water content data. The specific steps are as follows:

[0089] 1. Data fitting: Based on experimental data or previous research results, a relationship model between dielectric constant and water content (such as TOPP polynomial) is established.

[0090] 2. Model application: Substitute the calculated dielectric constant into the relationship model to solve the water content at each point.

[0091] Data visualization: Displaying moisture content data in the form of images or charts facilitates intuitive analysis of the distribution of moisture content in litter.

[0092] The above-mentioned point-to-surface combined litter moisture content monitoring system embodiment is not only applicable to forest ecosystems, but can also be extended to other types of ecosystems such as grasslands, wetlands, etc., and has wide applicability. By providing comprehensive and accurate moisture content data, it helps forest resource managers make more scientific decisions and improve management efficiency and protection effects.

Claims

1. A point-to-surface combined litter moisture monitoring system, comprising a moisture sensor, a moisture radar detector, and an edge sensing gateway, characterized in that: A plurality of monitoring points are arranged at intervals in the monitoring area, and the moisture content sensor is respectively arranged on the litter surface, the middle of the litter thickness and the litter ground surface at each monitoring point, and the moisture content radar detector is arranged at the edge of the monitoring area; The moisture sensors set at multiple monitoring points are used to monitor the moisture content on the surface of the litter, in the middle of the litter thickness, and on the ground where the litter touches the ground, thus forming point-like moisture content monitoring in the monitoring area. The moisture content radar detector scans the monitoring area to obtain the surface echo power change diagram of the litter, and obtains the surface moisture content distribution diagram of the monitoring area based on the relative relationship between the echo power and the moisture content, thus forming the surface moisture content monitoring of the monitoring area; The water content sensor is wirelessly connected to the edge perception gateway to exchange information, the water content radar detector is connected to the edge perception gateway through a wired or 4G / 5G network to exchange information, and the edge perception gateway is connected to the monitoring server; The water content sensor comprises an excitation signal source, a dual-ring probe, a detection circuit and a microprocessor. The dual-ring probe comprises a transmitting probe and two grounding probes, and the grounding probes are arranged at intervals on both sides of the transmitting probe. The excitation signal source is controlled by the microprocessor to output an oscillation signal of 50 MHz to 150 MHz through a coaxial cable to the transmitting probe. Signal lines are connected to the detection circuit at both ends of a middle section of the coaxial cable. The output of the detection circuit is connected to the microprocessor. The coaxial cable transmits the high-frequency oscillation signal to the dual-ring probe, and receives the reflected signal and sends it to the microprocessor through the detection circuit. The moisture content sensor uses the standing wave ratio method to determine the moisture content of the litter at the monitoring point. The standing wave ratio method has the following relationship: ； in: The two ends of the middle section of the coaxial cable, that is , The voltage difference between two points; ——The signal amplitude of the signal source output, in V; ——The impedance of the double-loop probe and its surrounding medium, in ohms; ——Characteristic impedance of coaxial transmission line, in ohms.

2. The monitoring system according to claim 1, characterized in that: The multiple monitoring points are distributed in a grid-like manner within the monitoring area.

3. The monitoring system according to claim 1, characterized in that: The water content radar detector is a synthetic aperture radar, and the monitoring area is a synthetic aperture radar scanning imaging area.

4. The monitoring system according to claim 1, characterized in that: The point moisture content monitoring provides accurate moisture content data for points in the monitoring area, and the surface moisture content monitoring provides moisture content distribution in the entire monitoring area. The two are integrated in real time through the edge sensing gateway to form comprehensive and accurate litter moisture content monitoring results.

5. The monitoring system according to claim 1, characterized in that: The system is provided with a point moisture content monitoring module, a surface moisture content monitoring module, a data acquisition and processing module, and a data transmission module; The point-shaped water content monitoring module is used to receive and record the water content data of the water content sensor at the monitoring point, and form a point-shaped distribution of the water content in the monitoring area; The surface moisture content monitoring module is used to receive and process the data of the moisture content radar detector scanning the monitoring area to form the surface distribution of the moisture content in the monitoring area; The data acquisition and processing module is used to perform data cleaning, denoising and smoothing on the moisture content data of the moisture content sensors at the monitoring points received and recorded, and the moisture content radar detector scanning monitoring area data received in the point moisture content monitoring module and the surface moisture content monitoring module. The processed data are integrated into a standard format for subsequent analysis and visualization; The data transmission module is used to transmit the point distribution, surface distribution and processed data to a data center or a user terminal in a safe mode.

6. The monitoring system according to claim 1, characterized in that: The surface moisture content distribution map of the monitoring area obtained according to the relative relationship between echo power and moisture content is as follows: the dielectric constant of each point of the echo power variation map is calculated according to the echo power and radar parameters, a relationship model between the dielectric constant and moisture content is established through experiments in the laboratory, the dielectric constant of each point of the echo power variation map is brought into the relationship model, and the surface moisture content distribution map of the monitoring area is obtained.

Images