An environmental monitoring system and method

Abstract

The application provides an environment monitoring system and method, which comprises the following steps: collecting the count rate data of cosmic ray neutrons in the saline-alkali soil by a neutron detector; extracting the energy attenuation characteristics of the cosmic ray neutrons from the count rate data; determining the absorption effect of the salt on the cosmic ray neutrons based on the energy attenuation characteristics and the salt concentration of the saline-alkali soil, correcting the slowing-down length of the cosmic ray neutrons and the water in the saline-alkali soil when colliding and slowing down according to the absorption effect, and obtaining the bound water distribution of the saline-alkali soil; measuring the temperature of the saline-alkali soil at different depths by a temperature sensor, quantifying the strength of the salt adsorption on the free water at different depths by the change trend of all the temperatures and the bound water distribution, obtaining the adsorption flux of the saline-alkali soil, and inversely correcting the measured water content of the saline-alkali soil according to the adsorption flux, and obtaining the effective water content of the saline-alkali soil. By the application, the influence of the combined water on the effective water content of the saline-alkali soil can be corrected.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of environmental monitoring, and more particularly to an environmental monitoring system and method. BACKGROUND

[0002] The saline-alkali soil plays an important role in ecological environment monitoring and agricultural production, and accurate monitoring of the soil water content thereof is crucial. Due to high salt content and complex mineral structure of the saline-alkali soil, the water state thereof presents significant heterogeneity. Under natural conditions, the soil water of the saline-alkali soil evaporates strongly due to the influence of climate conditions (such as in arid regions) and soil texture, resulting in accumulation of salt in the surface layer and complex phenomenon of internal water and salt migration.

[0003] In the environmental monitoring system, the water content of the saline-alkali soil needs to be evaluated. However, the salt will convert part of the free water in the saline-alkali soil into strongly bound water. The converted strongly bound water is immobile and cannot be absorbed and utilized by plants, and thus does not belong to the effective water content of the saline-alkali soil. In the prior art, conventional technologies such as drying method, dielectric constant method or time domain reflectometry are usually used to evaluate the water content of the saline-alkali soil. However, when the above conventional technologies are used to evaluate the water content of the saline-alkali soil, the distribution and conversion of the free water and the bound water cannot be effectively distinguished, and the evaluation result including the bound water and the free water is usually taken as the water state of the soil body as a whole, so that the effective water content of the saline-alkali soil cannot be reflected. Therefore, how to correct the influence of the bound water on the effective water content of the saline-alkali soil has become a difficult problem in the industry. SUMMARY

[0004] The present application provides an environmental monitoring system and method, which can correct the influence of the bound water on the effective water content of the saline-alkali soil.

[0005] In a first aspect, the present application provides a saline-alkali soil water content evaluation method for evaluating the water content of the saline-alkali soil by an environmental monitoring system, wherein the water of the saline-alkali soil contains free water and bound water, and the method comprises the following steps:

[0006] acquiring count rate data of cosmic ray neutrons in the saline-alkali soil by a neutron detector;

[0007] extracting energy attenuation characteristics of the cosmic ray neutrons in the saline-alkali soil from the count rate data;

[0008] determining an absorption effect of the salt on the cosmic ray neutrons based on the energy attenuation characteristics and the salt concentration of the saline-alkali soil, correcting the slowing-down length when the cosmic ray neutrons and the water in the saline-alkali soil collide and slow down according to the absorption effect, and then obtaining the bound water distribution of the saline-alkali soil when the free water and the bound water are phase-changed by the salt;

[0009] The temperature of the saline-alkali soil at different depths is measured by a temperature sensor, the adsorption strength of salt on free water at different depths is quantified by the variation trend of all temperatures and the bound water distribution, and an adsorption flux of the saline-alkali soil is obtained;

[0010] The measured water content of the saline-alkali soil is inversely corrected according to the adsorption flux, and an effective water content of the saline-alkali soil is obtained.

[0011] In some embodiments, extracting the energy attenuation feature of the cosmic ray neutron in the saline-alkali soil from the count rate data specifically includes:

[0012] Determining the count rate of the thermal neutron energy window in the cosmic ray neutron according to the count rate data;

[0013] Determining the count rate of the super-thermal neutron energy window in the cosmic ray neutron;

[0014] Determining the energy attenuation feature of the cosmic ray neutron in the saline-alkali soil based on the count rate of the super-thermal neutron energy window and the count rate of the thermal neutron energy window.

[0015] In some embodiments, determining the absorption effect of salt on the cosmic ray neutron based on the energy attenuation feature and the salt concentration of the saline-alkali soil specifically includes:

[0016] Obtaining the salt concentration of the saline-alkali soil;

[0017] Determining the absorption cross section of the salt in the saline-alkali soil on the cosmic ray neutron according to the salt concentration;

[0018] Determining the absorption effect of salt on the cosmic ray neutron by the absorption cross section and the energy attenuation feature.

[0019] In some embodiments, correcting the slowing-down length of the cosmic ray neutron and the water in the saline-alkali soil when colliding and slowing down according to the absorption effect, and then obtaining the bound water distribution of the saline-alkali soil when the free water and the bound water are phase-transformed by salt specifically includes:

[0020] Determining the slowing-down efficiency of the cosmic ray neutron and the water in the saline-alkali soil when colliding;

[0021] Correcting the slowing-down efficiency according to the absorption effect, and obtaining the corrected slowing-down length of the cosmic ray neutron in the saline-alkali soil;

[0022] Obtaining a preset soil water potential model;

[0023] Determining the conversion depth threshold of the free water into the bound water in the saline-alkali soil based on the salt concentration and the corrected slowing-down length;

[0024] determine a bound water distribution of the saline-alkali soil when the free water and the bound water are phase transitioned by the salt.

[0025] In some embodiments, the adsorption flux of the saline-alkali soil is determined by quantifying the adsorption strength of the salt on the free water at different depths through the change trend of all temperatures and the bound water distribution, and the adsorption flux of the saline-alkali soil specifically comprises:

[0026] determining the change trend at different depths of all temperatures;

[0027] determining the adsorption strength of the salt on the free water at different depths through the change trend and the bound water distribution;

[0028] determining the adsorption flux of the saline-alkali soil based on all the adsorption strengths.

[0029] In some embodiments, the effective water content of the saline-alkali soil is obtained by inversely correcting the measured water content of the saline-alkali soil according to the adsorption flux, and the effective water content of the saline-alkali soil specifically comprises:

[0030] obtaining the measured water content of the saline-alkali soil;

[0031] obtaining an inverse correction formula of the effective water content;

[0032] bringing the measured water content and the adsorption flux into the inverse correction formula to obtain the effective water content of the saline-alkali soil.

[0033] In some embodiments, the salt concentration of the saline-alkali soil is obtained by a portable salt detection instrument.

[0034] In a second aspect, the present application provides an environment monitoring system, which comprises a saline-alkali soil water content evaluation unit, and the saline-alkali soil water content evaluation unit comprises:

[0035] a collection module, configured to collect count rate data of cosmic ray neutrons in the saline-alkali soil by a neutron detector;

[0036] a processing module, configured to extract an energy attenuation feature of the cosmic ray neutrons in the saline-alkali soil from the count rate data;

[0037] The processing module is further configured to determine an absorption effect of the salt on the cosmic ray neutrons based on the energy attenuation feature and the salt concentration of the saline-alkali soil, correct a slowing-down length when the cosmic ray neutrons and the water in the saline-alkali soil collide and slow down according to the absorption effect, and further obtain a bound water distribution of the saline-alkali soil when the free water and the bound water are phase transitioned by the salt.

[0038] The processing module is further configured to measure the temperature of the saline-alkali soil at different depths by a temperature sensor, quantify the adsorption strength of the salt on the free water at different depths by a variation trend of all the temperatures and the bound water distribution, and obtain the adsorption flux of the saline-alkali soil.

[0039] The execution module is configured to correct the measured water content of the saline-alkali soil according to the adsorption flux, and obtain the effective water content of the saline-alkali soil.

[0040] In a third aspect, the present application provides a computer device, which comprises a memory and a processor, the memory stores a code, and the processor is configured to acquire the code and execute the above-mentioned saline-alkali soil water content evaluation method.

[0041] In a fourth aspect, the present application provides a computer readable storage medium, which stores a computer program, and the computer program is executed by a processor to implement the above-mentioned saline-alkali soil water content evaluation method.

[0042] The technical scheme provided by the embodiments of the present application has the following beneficial effects:

[0043] In the environment monitoring system and method provided by the present application, firstly, the counting rate data of cosmic ray neutrons in the saline-alkali soil are collected by a neutron detector; the energy attenuation characteristics of the cosmic ray neutrons in the saline-alkali soil are extracted from the counting rate data; the absorption effect of the salt on the cosmic ray neutrons is determined based on the energy attenuation characteristics and the salt concentration of the saline-alkali soil, the slowing-down length when the cosmic ray neutrons and the water in the saline-alkali soil collide and slow down is corrected according to the absorption effect, and then the bound water distribution of the saline-alkali soil when the free water and the bound water induced by the salt change phase is obtained; the temperatures of the saline-alkali soil at different depths are measured by a temperature sensor, the adsorption strength of the salt on the free water at different depths is quantified by a variation trend of all the temperatures and the bound water distribution, and the adsorption flux of the saline-alkali soil is obtained; and the measured water content of the saline-alkali soil is corrected by inversion according to the adsorption flux, and the effective water content of the saline-alkali soil is obtained.

[0044] It can be seen that, in the method for evaluating the water content of saline-alkali soil, first, the neutron detector is used to collect the counting rate data of cosmic ray neutrons in the saline-alkali soil; the energy attenuation characteristics of the cosmic ray neutrons in the saline-alkali soil are extracted from the counting rate data; the absorption effect of the salt on the cosmic ray neutrons is determined based on the energy attenuation characteristics and the salt concentration of the saline-alkali soil, and the slowing-down length of the cosmic ray neutrons and the water in the saline-alkali soil when colliding and slowing down is corrected according to the absorption effect, so as to obtain the bound water distribution of the saline-alkali soil when the free water and the bound water induced by the salt are phase changed, wherein the absorption effect refers to the effect of the reduction in the number of neutrons and the reduction in the energy of the cosmic ray neutrons caused by the absorption of the salt in the saline-alkali soil, and the bound water distribution refers to the content and distribution state of the water bound by the adsorption force of the salt particles or the attraction of the salt ions at different depths of the soil profile; secondly, the temperature sensor is used to measure the temperature of the saline-alkali soil at different depths, the adsorption strength of the free water at different depths is quantified by the change trend of all the temperatures and the bound water distribution, and the adsorption flux of the saline-alkali soil is obtained, the adsorption flux is the description of the free water converted into bound water by the adsorption of the salt per unit time, the absorption amount of the water per unit area of the saline-alkali soil is obtained, the measured water content of the saline-alkali soil is corrected according to the adsorption flux, and the effective water content of the saline-alkali soil is obtained, which can correct the influence of the bound water on the effective water content of the saline-alkali soil. BRIEF DESCRIPTION OF DRAWINGS

[0045] Figure 1 is an example flow chart of the method for evaluating the water content of saline-alkali soil according to some embodiments of the present application;

[0046] Figure 2 is an example flow chart of determining the energy attenuation characteristics according to some embodiments of the present application;

[0047] Figure 3 is a structural schematic diagram of a portable salt detection instrument according to some embodiments of the present application;

[0048] Figure 4 is a structural schematic diagram of a water content evaluation unit of saline-alkali soil according to some embodiments of the present application;

[0049] Figure 5 is a structural schematic diagram of a computer device for implementing the method for evaluating the water content of saline-alkali soil according to some embodiments of the present application. DETAILED DESCRIPTION

[0050] In order to better understand the above technical solutions, the above technical solutions will be described in detail below in combination with the drawings in the specification and specific embodiments.

[0051] REFERENCE Figure 1Fig. 1 is an exemplary flow chart of a method for evaluating the water content of saline-alkali soil according to some embodiments of the present application, which mainly includes the following steps:

[0052] In step 101, the count rate data of cosmic ray neutrons in the saline-alkali soil is collected by a neutron detector.

[0053] In practice, the count rate data of cosmic ray neutrons in the saline-alkali soil is obtained by collecting the number of counts of cosmic ray neutrons in the soil (0-100 cm) of the saline-alkali soil per unit time by a neutron detector (such as a super-thermal neutron-thermal neutron dual-energy window detector), wherein the cosmic ray neutrons include thermal neutrons and super-thermal neutrons, and the count rate data of cosmic ray neutrons refers to the number of effective pulse signals caused by cosmic ray neutrons recorded per unit time.

[0054] In step 102, the energy attenuation characteristics of the cosmic ray neutrons in the saline-alkali soil are extracted from the count rate data.

[0055] In some embodiments, referring to Fig. 2, which is an exemplary flow chart of determining the energy attenuation characteristics according to some embodiments of the present application, the extraction of the energy attenuation characteristics of the cosmic ray neutrons in the saline-alkali soil from the count rate data can be achieved by the following steps: Figure 2 First, in step 1021, the count rate of the thermal neutron energy window in the cosmic ray neutrons is determined according to the count rate data.

[0056] Second, in step 1022, the count rate of the super-thermal neutron energy window in the cosmic ray neutrons is determined.

[0057] Finally, in step 1023, the energy attenuation characteristics of the cosmic ray neutrons in the saline-alkali soil are determined based on the count rate of the super-thermal neutron energy window and the count rate of the thermal neutron energy window.

[0058]

[0059] ​In a specific implementation, the determination of the count rate of the thermal neutron energy window in the cosmic ray neutrons according to the count rate data can be achieved in the following manner: first, based on the pulse height analysis (PHA) algorithm in the prior art, the original pulse signals collected by the neutron detector are classified according to the amplitudes of the signals, thereby preliminarily screening out the pulse signals in the energy range of the thermal neutron energy window; second, in combination with the multi-channel analyzer (MCA) technology, the pulse signals classified by the PHA are distributed to different energy channels according to their amplitudes, and the pulse signals falling within the preset thermal neutron energy boundary are counted into the corresponding channels, thereby further dividing the channels corresponding to the energy range of the thermal neutron energy window; finally, the pulse signals in the channels corresponding to the thermal neutron energy window are counted to obtain the count rate of the thermal neutron energy window; wherein one channel corresponds to one amplitude energy interval, the thermal neutron energy window refers to a specific energy interval in which the thermal neutron is located during the moderation process, and is generally 0.005 eV to 0.5 eV, which is set to 0.01 eV to 0.5 eV in the present application, and the thermal neutron energy boundary refers to the upper and lower limits of the thermal neutron energy, which is set to the lower boundary 0.01 eV and the upper boundary 0.5 eV in the present application, wherein the count rate of the thermal neutron energy window refers to the number of thermal neutrons detected per unit time within the energy window of the thermal neutron; in other embodiments, other methods can also be used for determination, which are not limited here.

[0060] In a specific implementation, the determination of the count rate of the thermal neutron energy window in the cosmic ray neutrons according to the count rate data can be achieved in the following manner: first, based on the pulse height analysis (PHA) algorithm in the prior art, the original pulse signals collected by the neutron detector are classified according to the amplitudes of the signals, thereby preliminarily screening out the pulse signals in the energy range of the thermal neutron energy window; second, in combination with the multi-channel analyzer (MCA) technology, the pulse signals classified by the PHA are distributed to different energy channels according to their amplitudes, and the pulse signals falling within the preset thermal neutron energy boundary are counted into the corresponding channels, thereby further dividing the channels corresponding to the energy range of the thermal neutron energy window; finally, the pulse signals in the channels corresponding to the thermal neutron energy window are counted to obtain the count rate of the thermal neutron energy window; wherein one channel corresponds to one amplitude energy interval, the thermal neutron energy window refers to a specific energy interval in which the thermal neutron is located during the moderation process, and is generally 0.005 eV to 0.5 eV, which is set to 0.01 eV to 0.5 eV in the present application, and the thermal neutron energy boundary refers to the upper and lower limits of the thermal neutron energy, which is set to the lower boundary 0.01 eV and the upper boundary 0.5 eV in the present application, wherein the count rate of the thermal neutron energy window refers to the number of thermal neutrons detected per unit time within the energy window of the thermal neutron; in other embodiments, other methods can also be used for determination, which are not limited here.

[0061] In a specific implementation, determining the energy attenuation characteristics of cosmic ray neutrons in the saline soil based on the count rates of the epithermal neutron energy window and the thermal neutron energy window can be implemented in the following manner: first, normalize the count rates of the epithermal neutron energy window and the thermal neutron energy window (e.g., maximum or minimum normalization) to eliminate errors caused by differences in detector sensitivity; second, use a ratio calculation model to calculate the characteristic ratio of the count rate of the thermal neutron energy window to the count rate of the epithermal neutron energy window; third, use a machine learning algorithm (e.g., a support vector machine) to train a training set of known characteristic ratios of saline soil samples and actual energy attenuation coefficients, establish a mapping relationship between the characteristic ratios of the saline soil samples and the actual energy attenuation coefficients, and obtain a depth calibration curve, thereby converting the characteristic ratio to the corresponding energy attenuation coefficient through the mapping relationship combined with the depth calibration curve; and finally, use the calculated energy attenuation coefficient as the energy attenuation characteristics of cosmic ray neutrons in the saline soil, which can be used to analyze the energy loss of neutrons during interaction with the saline soil medium in subsequent analysis. In other embodiments, other methods can be used to determine the energy attenuation characteristics, which are not limited here.

[0062] It should be noted that the characteristic ratio in this application refers to the ratio of the count rate of the thermal neutron energy window to the count rate of the epithermal neutron energy window, which is used to reflect the degree of moderation of cosmic ray neutrons in the saline soil, i.e., the degree of conversion of epithermal neutrons to thermal neutrons. The more the conversion, the larger the characteristic ratio, and the higher the energy attenuation. The depth calibration curve is a curve describing the quantitative relationship between the characteristic ratio and the energy attenuation coefficient, with the horizontal axis representing the characteristic ratio and the vertical axis representing the energy attenuation coefficient. The ratio calculation model may, for example, be: characteristic ratio = count rate of thermal neutron energy window / count rate of epithermal neutron energy window. The energy attenuation characteristics refer to the characteristics of the energy attenuation of cosmic ray neutrons in the saline soil, which are characterized by the energy attenuation coefficient, and are used to reflect the overall energy loss of cosmic ray neutrons during interaction with the saline soil medium, facilitating subsequent analysis of the absorption of cosmic ray neutrons by salt in the saline soil medium.

[0063] In step 103, the absorption effect of salt on the cosmic ray neutrons is determined based on the energy attenuation characteristics and the salt concentration of the saline soil, and the moderation length of the cosmic ray neutrons and the water in the saline soil when colliding and moderating is corrected according to the absorption effect, thereby obtaining the bound water distribution of the saline soil when the free water and bound water induced by salt phase change.

[0064] In some embodiments, determining the absorption effect of salt on the cosmic ray neutrons based on the energy attenuation characteristics and the salt concentration of the saline soil can be implemented in the following steps:

[0065] Obtain the salt concentration of the saline soil;

[0066] The absorption cross section of the salt in the saline-alkali land for the cosmic ray neutrons is determined based on the salt concentration.

[0067] The absorption effect of salt on cosmic ray neutrons is determined by the absorption cross section and the energy decay characteristics.

[0068] In practice, determining the absorption cross section of cosmic ray neutrons by the salt in the saline-alkali land based on the salt concentration can be achieved in the following way: First, the actual salt concentration and the proportion of various salt components (such as sodium chloride, sodium sulfide, etc.) of the saline-alkali land are detected using a portable salt detection instrument, and then referenced... Figure 3 As shown in the figure, this is a schematic diagram of the structure of a portable salinity detection instrument in some embodiments of this application. Next, basic data on the neutron absorption cross-sections of various salt components in saline-alkali land are obtained through a neutron cross-section database (such as the China Evaluation Nuclear Database). This basic data includes nuclide information, neutron absorption cross-section values, and cross-section energy variation trends. Then, the neutron absorption cross-sections of each salt in the saline-alkali land are weighted and calculated to obtain the equivalent absorption cross-section of the mixed salts. The weighted calculation formula can be, for example: Equivalent absorption cross-section of mixed salts = The mass fraction (i.e., percentage) of the i-th salt is multiplied by the neutron absorption cross-section value of the i-th salt, where i is an index variable used to represent different salts in the saline-alkali land, i.e., the subscript used to distinguish and traverse various salts in the saline-alkali land. Then, samples with similar salt composition to the target saline-alkali land are selected from the saline-alkali land monitoring station, and the neutron count rate change of samples with different salt concentrations is measured using experimental calibration techniques to establish a calibration curve of salt concentration and neutron absorption cross-section of the saline-alkali land. Finally, the real-time salt concentration of the saline-alkali land obtained by actual measurement is substituted into the calibration curve and the mixed medium calculation model using a mixed medium theoretical model (such as the extended model of the Bethlehem formula) to obtain the absorption cross-section of the salt in the saline-alkali land for the cosmic ray neutrons. The absorption cross-section is a physical quantity describing the absorption reaction between cosmic ray neutrons and the atomic nuclei of the salt components in the saline-alkali land per unit area, reflecting the ability of the atomic nuclei of the salt components in the saline-alkali land to absorb cosmic ray neutrons. Other methods can also be used to determine this in other embodiments, which are not limited here.

[0069] In a specific implementation, the determination of the absorption effect of the salt on the cosmic ray neutrons based on the absorption cross section and the energy attenuation feature can be achieved in the following manner. First, the soil texture of the soil sample of the saline-alkali soil is collected and analyzed by a particle size analyzer (e.g., a laser particle size analyzer). The soil texture refers to the composition ratio of particles (e.g., sand particles, silt particles, and clay particles) of different particle sizes in the soil of the saline-alkali soil. According to the Boltzmann transport equation in the neutron transport theory, the absorption cross section, the soil texture of the saline-alkali soil, and the real-time salt concentration of the saline-alkali soil are all taken as known initial parameters of the cosmic ray neutrons during the transport in the saline-alkali soil medium, and the energy attenuation feature is taken as a known constraint parameter of the cosmic ray neutrons during the transport in the saline-alkali soil medium. Then, the initial parameters and the constraint parameter are brought into the Boltzmann transport equation to simulate the energy loss of the cosmic ray neutrons during the transport in the saline-alkali soil, and the neutron flux loss and the energy distribution of the cosmic ray neutrons during the transport in the saline-alkali soil are obtained. The neutron flux loss is a parameter value that describes the reduction degree of the number of neutrons passing through a unit area per unit time. The energy distribution refers to the distribution of the energy of the remaining neutrons after the absorption of the cosmic ray neutrons by the saline-alkali soil medium. Finally, the neutron flux loss and the energy distribution of the cosmic ray neutrons are taken as the absorption effect of the salt on the cosmic ray neutrons. In other embodiments, the absorption effect can also be determined in other manners, which are not limited here.

[0070] It should be noted that the Boltzmann transport equation in the present application is used to describe the distribution change of neutrons during the movement in the medium due to absorption, scattering, and other interactions. The saline-alkali soil can be regarded as a mixed medium composed of soil, water, and salt. Therefore, the transport model of the cosmic ray neutrons during the transport in the saline-alkali soil medium can be established in combination with the material density parameters (i.e., the salt concentration and the soil texture) of the saline-alkali soil. The energy attenuation coefficient reflects the actual energy loss of the cosmic ray neutrons in the saline-alkali soil, and thus can be regarded as a constraint condition in the transport process of the cosmic ray neutrons. Therefore, the absorption effect of the salt on the cosmic ray neutrons during the transport process can be obtained according to the transport model. The absorption effect refers to the effect of the reduction of the number of neutrons and the reduction of the energy caused by the absorption of the cosmic ray neutrons by the salt in the saline-alkali soil. The absorption effect is represented by the neutron flux loss and the energy distribution. The absorption effect is used to react the hindering of the transport process of the cosmic ray neutrons by the salt in the saline-alkali soil, which facilitates the subsequent correction of the moderation process of the cosmic ray neutrons.

[0071] In some embodiments, the moderation length of the collision between the cosmic ray neutrons and the water in the saline-alkali soil is corrected based on the absorption effect, and then the bound water distribution of the saline-alkali soil during the phase transition of the free water and the bound water induced by the salt can be obtained in the following steps.

[0072] The moderation efficiency of the collision between the cosmic ray neutrons and the water in the saline-alkali soil is determined.

[0073] correcting the slowing-down efficiency according to the absorption effect, to obtain a corrected slowing-down length of the cosmic ray neutron in the saline-alkali soil;

[0074] obtaining a preset soil water potential model;

[0075] determining a conversion depth threshold of free water into bound water in the saline-alkali soil based on the salt concentration and the corrected slowing-down length;

[0076] determining a bound water distribution of the saline-alkali soil when the salt induces the phase transition of free water and bound water according to the conversion depth threshold and the soil water potential model.

[0077] In a specific implementation, the slowing-down efficiency of the cosmic ray neutron and the water in the saline-alkali soil can be determined in the following manner. First, the cosmic ray neutron in the saline-alkali soil is taken as a neutron source, where the neutron source includes the energy distribution and quantity of thermal neutrons and super-thermal neutrons, so as to bring the neutron source into a neutron slowing-down density equation, and simulate the collision process of the cosmic ray neutron and the water molecule in the saline-alkali soil by combining an elastic scattering model (such as a Monte Carlo model) in a neutron transport theory, so as to solve the neutron slowing-down density equation and obtain the average collision number required by the cosmic ray neutron to slow down from a high-energy state to an energy window of thermal neutrons. Second, by combining an experimental calibration method with a saline-alkali soil sample with a known water content (which can be obtained from an ecological observation test station), an empirical relationship between the average collision number required by the cosmic ray neutron to slow down from a high-energy state to an energy window of thermal neutrons in the sample and the slowing-down efficiency of the neutron in the sample is obtained, so as to map and correlate the empirical relationship with the average collision number required by the cosmic ray neutron to slow down from a high-energy state to an energy window of thermal neutrons in the saline-alkali soil, to obtain the actual slowing-down efficiency of the cosmic ray neutron and the water in the saline-alkali soil. In other embodiments, the slowing-down efficiency can also be determined in other manners, which are not limited herein.

[0078] It should be noted that the elastic scattering model in the present application is a model established based on the quantum mechanics principle and the influence of factors such as neutron energy and scattering angle on the collision result. The elastic scattering model can calculate the average energy loss of each collision of the neutron, and the neutron slowing-down density equation is an equation describing the slowing-down degree of the neutron in the saline-alkali soil medium per unit time and per unit volume. Therefore, the slowing-down efficiency can be represented by the average collision number during the slowing-down of the neutron, that is, the collision process of the cosmic ray neutron in the saline-alkali soil is simulated by the elastic scattering model to solve the neutron slowing-down density equation. The slowing-down efficiency is a parameter value representing the ability of the cosmic ray neutron to slow down from a high-energy state to an energy window of thermal neutrons and super-thermal neutrons in the saline-alkali soil medium.

[0079] In a specific implementation, the correction of the moderation efficiency according to the absorption effect to obtain the corrected moderation length of the cosmic ray neutron in the saline land can be achieved in the following manner: first, the scattering cross-section data of water molecules are obtained from the Chinese Evaluated Nuclear Data Library, and the scattering cross-section data of water molecules and the neutron absorption cross-section values of various salt components in the saline land are both taken as known parameters to be brought into the reference moderation length model, and the neutron flux loss and the energy distribution in the absorption effect are both taken as the constraint conditions of the moderation of the cosmic ray neutron by the salt in the saline land to be brought into the reference moderation length model, so as to calculate the path length of the cosmic ray neutron in each collision, and correct the moderation efficiency of the cosmic ray neutron through the above constraint conditions, and finally statistically obtain the corrected neutron moderation path distribution, wherein the neutron moderation path distribution refers to the probability distribution of the path length of the cosmic ray neutron in the saline land medium from generation to moderation into a thermal neutron; finally, the neutron moderation path distribution is statistically analyzed, and the expectation value of the moderation length is extracted as the corrected moderation length of the cosmic ray neutron in the saline land, wherein the moderation length is a parameter value describing the straight-line distance of the cosmic ray neutron from generation to moderation into a thermal neutron; in other embodiments, other ways can also be used to determine, which is not limited here.

[0080] It should be noted that the reference moderation length model in the present application refers to the root mean square value of the straight-line distance of the neutron from generation to moderation into a thermal neutron, and the model of the reference moderation length is constructed, which is used as a reference for the ideal state of the cosmic ray neutron moderation process when not affected by salt, for comparison of the change of the cosmic ray neutron moderation path under the condition of the saline land medium, so as to quantify the influence degree of the salt on the cosmic ray neutron moderation; the moderation length is used to reflect the path length of the cosmic ray neutron in the moderation process, and the shorter the moderation length, the higher the efficiency of the neutron moderation by the salt medium in the saline land.

[0081] In a specific implementation, the determination of the threshold depth of the conversion of free water into bound water in the saline-alkali soil based on the salt concentration and the corrected slowing-down length can be achieved in the following manner. First, the real-time salt concentration of the saline-alkali soil and the soil texture of the saline-alkali soil are both taken as known input parameters and input into a salt concentration and soil particle surface adsorption force model (e.g., the Debye-Hückel model) to calculate the electrostatic potential distribution of the saline-alkali soil and the double electric layer thickness of the salt at each depth position in the profile model. Second, the empirical relationship between the corrected slowing-down length of cosmic-ray neutrons in a saline-alkali soil sample with a known water content and the water content of the saline-alkali soil sample is established by simulating the neutron slowing-down of the saline-alkali soil sample with a known water content and using a mathematical analysis method (e.g., the differential equation method). Third, the double electric layer thickness of the salt of the saline-alkali soil, the electrostatic potential distribution, and the above-mentioned empirical relationship are combined to calculate the critical water content at which the free water starts to be converted into bound water. The critical water content refers to the minimum water content at which the free water starts to be combined with the salt particles of the saline-alkali soil and converted into bound water. Then, the depth of the critical water content is calibrated based on the actual salt concentration and water content distribution at different depths of the saline-alkali soil sample with a known water content. In combination with the above-mentioned adsorption force model and the critical water content, the threshold depth of the conversion of free water into bound water in the saline-alkali soil is inversely calculated. The threshold depth of the conversion of free water into bound water refers to the threshold of the depth at which the free water is converted into bound water in the saline-alkali soil. In other embodiments, the threshold depth of the conversion of free water into bound water can also be determined in other manners, which are not limited herein.

[0082] It should be noted that the adsorption force model in the present application is a mathematical model of the salt concentration and the adsorption force of the soil particle surface established based on the diffuse double electric layer theory in soil physics. The model can quantify the binding of water molecules by the salt in the saline-alkali soil according to the actual salt ion species (e.g., sodium ions and chloride ions) and the salt concentration in the saline-alkali soil, thereby reflecting the ability of the salt in the saline-alkali soil to attenuate the energy of cosmic-ray neutrons, i.e., the double electric layer thickness and the electrostatic potential distribution of the salt in the saline-alkali soil. The slowing-down length reflects the average distance of the slowing-down of cosmic-ray neutrons to the thermal neutron energy region in the saline-alkali soil medium. Therefore, by comparing the experimental data of the slowing-down length under different water contents (of the saline-alkali soil sample with a known water content), the adsorption force of the saline-alkali soil (i.e., the conversion of bound water) under the current slowing-down length of the saline-alkali soil can be fitted, thereby obtaining the threshold depth of the conversion of free water into bound water.

[0083] In a specific implementation, the determination of the bound water distribution of the saline-alkali soil when the free water and the bound water are transformed by the salt can be achieved by the following method: spatial interpolation is performed on the saline-alkali soil investigation database (such as the second national soil survey data) to generate a profile model of the saline-alkali soil in the target area, the conversion depth threshold is used as the basis for vertical space division, the depth less than the conversion depth threshold in the profile model of the saline-alkali soil is regarded as the shallow free water area, and the depth greater than or equal to the conversion depth threshold in the profile model of the saline-alkali soil is regarded as the deep bound water area; secondly, all the electrostatic potentials and all the double-layer thicknesses in the deep bound water area are used as the initialization parameters, and the salt concentration of the saline-alkali soil is used as the constraint parameter, which are input into the soil water potential model (Van Genuchten, VG) to obtain the bound water distribution of the saline-alkali soil at different depths when the free water and the bound water are transformed by the salt, wherein the soil water potential model is a model of the soil water potential established by using a machine learning algorithm (such as a decision tree, a neural network, etc.), which is used to describe the energy state of the water in the saline-alkali soil, and the soil water potential model is composed of the matric potential (i.e., the electrostatic potential and all the double-layer thicknesses of the deep bound water area of the saline-alkali soil) and the gravitational potential (the profile model of the saline-alkali soil); the profile model is a three-dimensional model of the soil properties of the saline-alkali soil in the target area varying with the depth; in other embodiments, the determination can also be achieved by other methods, which are not limited here.

[0084] It should be noted that the bound water distribution in the present application refers to the content and distribution state of the water bound by the salt particle surface adsorption force or the salt ion electric charge attraction in the saline-alkali soil at different depth positions of the soil profile, and the bound water distribution includes a three-dimensional depth coordinate (i.e., the three-dimensional coordinates of each depth obtained by the profile model) and a bound water content, one depth coordinate corresponds to one bound water content; the bound water cannot flow freely and is difficult to be absorbed and utilized by plant roots, and the distribution of the bound water directly affects the soil water holding capacity, the salt transport and the water availability of the ecological system, therefore, the bound water distribution can be used to analyze the influence of the salt on the transformation of the free water into the bound water in the cosmic ray neutrons in the saline-alkali soil, and to facilitate the subsequent correction of the estimated water content of the saline-alkali soil.

[0085] In step 104, the temperature of the saline-alkali soil at different depths is measured by a temperature sensor, the adsorption strength of the salt on the free water at different depths is quantified by the change trend of all the temperatures and the bound water distribution, and the adsorption flux of the saline-alkali soil is obtained.

[0086] In a specific implementation, the soil of the saline-alkali land is divided into multiple soil layers, wherein two adjacent soil layers are spaced apart by 10 cm, multiple position coordinates are obtained by a mathematical modeling software (MATrix LABoratory, MATLAB) in combination with a profile model of the saline-alkali land, wherein the position coordinates are three-dimensional coordinates including a horizontal axis, a vertical axis and a vertical axis, so that a temperature sensor (such as a platinum resistance temperature sensor) is arranged at a center position of each soil layer to measure and collect real-time temperature data of each soil layer, wherein a sampling time is 100 Hz, and one temperature data corresponds to one time point.

[0087] In some embodiments, the adsorption flux of the saline-alkali land is quantified by the change trend of all temperatures and the bound water distribution to obtain the adsorption strength of the salt on the free water at different depths, which can be achieved by the following steps:

[0088] determining the change trend of all temperatures at different depths;

[0089] determining the adsorption strength of the salt on the free water at different depths by the change trend and the bound water distribution;

[0090] determining the adsorption flux of the saline-alkali land based on all the adsorption strengths.

[0091] In a specific implementation, the change trend of all temperatures at different depths can be achieved by the following method, that is, all temperature data and depth data collected are calculated by a mathematical analysis method (such as a differential method) to obtain a temperature gradient of each temperature data, and a set of all temperature data of the temperature gradient is taken as the change trend of all temperatures at different depths, wherein the change trend describes the change trend of the temperature of the saline-alkali land at different depths; in other embodiments, other methods can also be used to determine the change trend, which is not limited here.

[0092] In a specific implementation, the determination of the adsorption strength of salt at different depths on free water through the change trend and the bound water distribution can be achieved in the following manner: the saline-alkali soil is divided into multiple soil layers according to the collected depth data, wherein the interval of two adjacent soil layers is set to 10 cm, any two adjacent soil layers are selected as selected two soil layers, the mean values of the bound water contained in the selected two soil layers are calculated, and then the adsorption strength of the selected two soil layers is calculated according to the mean values of the bound water corresponding to the selected two soil layers, the conversion depth threshold and the change trend of the temperature, wherein the adsorption strength is a parameter value describing the increment of the bound water adsorbed by salt between two adjacent soil layers, and is used to reflect the water potential change inside the saline-alkali soil. The adsorption strength between the remaining any two adjacent soil layers is continuously determined; the determination of the adsorption flux of the saline-alkali soil based on all the adsorption strengths can be achieved in the following manner: the inverse distance weighted interpolation method is used to expand the discrete adsorption strengths of the adjacent soil layers into a continuous adsorption strength distribution, the adsorption strength distribution is input into the Richards equation as a known parameter, the water movement at each depth of the saline-alkali soil is modeled according to the equation, and the above model is solved by combining the finite element method (such as the adaptive finite element method), so as to obtain the water flux of each soil layer; finally, the water flux and the adsorption strength are calculated by the Levenberg-Marquardt algorithm to obtain the adsorption flux of the saline-alkali soil, wherein the water flux refers to the volume of water passing through a unit area of soil of the saline-alkali soil per unit time; in other embodiments, other methods can also be used for determination, which is not limited here.

[0093] It should be noted that the adsorption flux in the present application is the absorption amount of water per unit time, which is used to convert the free water into bound water by salt, and is used to quantitatively analyze the influence of the cosmic ray neutron affected by salt (characterized as the conversion of water form) so as to facilitate the correction of the moisture content detection of the saline-alkali soil interfered by salt.

[0094] In step 105, the measured moisture content of the saline-alkali soil is inversely corrected according to the adsorption flux to obtain the effective moisture content of the saline-alkali soil.

[0095] In some embodiments, the determination of the effective moisture content of the saline-alkali soil by inversely correcting the measured moisture content of the saline-alkali soil according to the adsorption flux can be achieved in the following steps:

[0096] The measured moisture content of the saline-alkali soil is obtained;

[0097] An inverse correction formula of the effective moisture content is obtained;

[0098] The measured moisture content and the adsorption flux are input into the inverse correction formula to obtain the effective moisture content of the saline-alkali soil.

[0099] In a specific implementation, the portable neutron moisture meter is deployed to collect cosmic ray neutrons in the saline-alkali soil, a calibration relationship between thermal neutron count rate and water content is obtained from a Chinese evaluation nuclear database, and thus the measured water content of the saline-alkali soil is obtained according to the calibration relationship and the thermal neutron count rate of the collected cosmic ray neutrons in the saline-alkali soil; the measured water content and the adsorption flux are brought into the inversion correction formula to obtain the effective water content of the saline-alkali soil. The effective water content of the saline-alkali soil can be obtained by bringing the measured water content and the adsorption flux into the inversion correction formula, wherein the effective water content refers to the total amount of free water that actually has fluidity and biological availability after deducting the bound water adsorbed by salt, and is used for quantitative analysis of water in the saline-alkali soil that can be directly utilized, thereby facilitating monitoring of the ecological environment of the saline-alkali soil; the inversion correction formula can be, for example, effective water content = measured water content - k x adsorption flux, k is a correction coefficient, which can be obtained by least squares fitting of a training set of effective water content; in other embodiments, the effective water content of the saline-alkali soil can also be obtained by other means, which are not limited here.

[0100] In addition, another aspect of the present application provides an environment monitoring system, which includes a saline-alkali soil water content evaluation unit, which is configured to Figure 4 The figure is a structural schematic diagram of a saline-alkali soil water content evaluation unit according to some embodiments of the present application, which includes an acquisition module 401, a processing module 402, and an execution module 403, which are described as follows:

[0101] The acquisition module 401 is mainly used to acquire count rate data of cosmic ray neutrons in the saline-alkali soil by a neutron detector in the present application;

[0102] The processing module 402 is used to extract the energy attenuation characteristics of the cosmic ray neutrons in the saline-alkali soil from the count rate data in the present application;

[0103] It should be noted that the processing module 402 is also used to determine the absorption effect of salt on the cosmic ray neutrons based on the energy attenuation characteristics and the salt concentration of the saline-alkali soil, correct the slowing-down length when the cosmic ray neutrons and the water in the saline-alkali soil collide and slow down according to the absorption effect, and further obtain the bound water distribution of the saline-alkali soil when the salt-induced free water and bound water phase change;

[0104] In addition, it should be noted that the processing module 402 is also used to measure the temperature of the saline-alkali soil at different depths by a temperature sensor, quantify the adsorption strength of salt on free water at different depths by the change trend of all temperatures and the bound water distribution, and obtain the adsorption flux of the saline-alkali soil.

[0105] The execution module 403 in this application is mainly used to perform inversion correction on the measured water content of the saline-alkali land based on the adsorption flux, so as to obtain the effective water content of the saline-alkali land.

[0106] In addition, this application also provides a computer device, the computer device including a memory and a processor, the memory storing code, and the processor being configured to acquire the code and execute the above-described method for assessing the water content of saline-alkali land.

[0107] In some embodiments, reference Figure 5 The figure is a schematic diagram of the structure of a computer device for implementing a method for assessing the water content of saline-alkali land according to some embodiments of this application. The method for assessing the water content of saline-alkali land in the above embodiments can be implemented through... Figure 5 The computer device shown is used to implement this, and the computer device includes at least one processor 501, a communication bus 502, a memory 503, and at least one communication interface 504.

[0108] Processor 501 can be a general-purpose central processing unit (CPU) or an application-specific integrated circuit (ASIC).

[0109] The communication bus 502 can be used to transmit information between the aforementioned components.

[0110] Memory 503 may be a read-only memory (ROM) or other type of static storage device capable of storing static information and instructions, random access memory (RAM) or other type of dynamic storage device capable of storing information and instructions, or electrically erasable programmable read-only memory (EEPROM), compact disc read-only memory (CDROM) or other optical disc storage, optical disc storage (including compressed optical discs, laser discs, optical discs, digital versatile optical discs, Blu-ray discs, etc.), magnetic disks or other magnetic storage devices, or any other medium capable of carrying or storing desired program code in the form of instructions or data structures and accessible by a computer, but not limited thereto. Memory 503 may exist independently and be connected to processor 501 via communication bus 502. Memory 503 may also be integrated with processor 501.

[0111] The memory 503 is configured to store a program code for implementing the scheme of the present application, and the processor 501 is configured to execute the program code stored in the memory 503. The program code can include one or more software modules. The method used in the above-described embodiments can be implemented by the processor 501 and one or more software modules in the program code in the memory 503.

[0112] The communication interface 504 is configured to communicate with other devices or communication networks, such as an Ethernet, a radio access network (RAN), a wireless local area network (WLAN), etc., using any transceiver-like device.

[0113] In a specific implementation, as an example, the computer device can include a plurality of processors, each of which can be a single CPU processor or a multi-CPU processor. The processor herein can refer to one or more devices, circuits, and / or processing cores for processing data (e.g., computer program instructions).

[0114] The computer device described above can be a general-purpose computer device or a special-purpose computer device. In a specific implementation, the computer device can be a desktop computer, a laptop computer, a network server, a personal digital assistant (PDA), a mobile phone, a tablet computer, a wireless terminal device, a communication device, or an embedded device. The embodiments of the present application do not limit the type of the computer device.

[0115] In addition, the present application also provides a computer-readable storage medium, which stores a computer program. The computer program is executed by a processor to implement the above-mentioned saline soil moisture content evaluation method.

[0116] Although the preferred embodiments of the present application have been described, those skilled in the art can make further changes and modifications to the embodiments once they know the basic inventive concept. Therefore, the appended claims are intended to cover all changes and modifications falling within the scope of the present application.

[0117] Obviously, those skilled in the art can make various modifications and variations to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalent technologies, the present application is also intended to include these modifications and variations.

Claims

1. A method for assessing the water content of saline-alkali land, used in an environmental monitoring system to assess the water content of saline-alkali land, wherein, The moisture in the saline-alkali land comprises free water and bound water, characterized in that the method includes the following steps: The count rate data of cosmic ray neutrons in the saline-alkali land were collected using a neutron detector. The energy decay characteristics of cosmic ray neutrons in saline-alkali land were extracted from the count rate data. Based on the energy decay characteristics and the salt concentration of the saline-alkali land, the absorption effect of salt on the cosmic ray neutrons is determined. The slowing length when the cosmic ray neutrons collide with water in the saline-alkali land is corrected according to the absorption effect, and then the distribution of bound water in the saline-alkali land during the phase transition between salt-induced free water and bound water is obtained. The temperature of the saline-alkali land at different depths is measured by a temperature sensor. The adsorption intensity of salt at different depths of free water is quantified by the trend of all temperature changes and the distribution of bound water, and the adsorption flux of the saline-alkali land is obtained. The measured water content of the saline-alkali land is inverted and corrected based on the adsorption flux to obtain the effective water content of the saline-alkali land; Specifically, determining the absorption effect of salt on cosmic ray neutrons based on the energy attenuation characteristics and the salt concentration of the saline-alkali land includes: Obtain the salt concentration of the saline-alkali land; The absorption cross section of the salt in the saline-alkali land for the cosmic ray neutrons is determined based on the salt concentration. The absorption effect of salt on cosmic ray neutrons is determined by the absorption cross section and the energy attenuation characteristics. Specifically, the slowing-down length of the collision between the cosmic ray neutron and the water in the saline-alkali land is corrected according to the absorption effect, thereby obtaining the specific distribution of bound water in the saline-alkali land during the salt-induced phase transition between free water and bound water, including: Determine the moderating efficiency of the collision between the cosmic ray neutron and the water in the saline-alkali land; The moderation efficiency is corrected based on the absorption effect to obtain the corrected moderation length of the cosmic ray neutron in the saline-alkali land. Obtain the preset soil water potential model; The conversion depth threshold for free water to be converted into bound water in the saline-alkali land is determined based on the salinity concentration and the corrected slowing length. The distribution of bound water in the saline-alkali land during the phase transition between salt-induced free water and bound water is determined based on the conversion depth threshold and the soil water potential model. Specifically, the effective water content of the saline-alkali land is obtained by inverting and correcting the measured water content based on the adsorption flux, including: Obtain the measured water content of the saline-alkali land; The inversion correction formula for obtaining effective water content; Substituting the measured water content and the adsorption flux into the inversion correction formula, the effective water content of the saline-alkali land is obtained. The inversion correction formula is: effective water content = measured water content − k × adsorption flux, where k is the correction coefficient. The effective water content is obtained by fitting the training set of the training data using the least squares method.

2. The method as described in claim 1, characterized in that, Extracting the energy decay characteristics of cosmic ray neutrons in saline-alkali land from the count rate data specifically includes: The count rate of the thermal neutron energy window in the cosmic ray neutrons is determined based on the count rate data; Determine the count rate of the hyperthermal neutron energy window in the cosmic ray neutrons; The energy decay characteristics of cosmic ray neutrons in saline-alkali land are determined based on the count rate of the ultrathermal neutron energy window and the count rate of the thermal neutron energy window.

3. The method as described in claim 1, characterized in that, By quantifying the adsorption intensity of salt in free water at different depths based on the variation trends of all temperatures and the distribution of bound water, the adsorption flux of the saline-alkali land is obtained, specifically including: Determine the trends of temperature variation at different depths; The adsorption intensity of salt on free water at different depths was determined by the changing trend and the bound water distribution. The adsorption flux of the saline-alkali land was determined based on all adsorption intensities.

4. The method as described in claim 1, characterized in that, The salt concentration of the saline-alkali land was obtained using a portable salt detection instrument.

5. An environmental monitoring system, which performs environmental monitoring using the method described in any one of claims 1 to 4, the environmental monitoring system comprising a saline-alkali land water content assessment unit, characterized in that, The saline-alkali land moisture content assessment unit includes: The acquisition module is used to acquire count rate data of cosmic ray neutrons in the saline-alkali land through a neutron detector; The processing module is used to extract the energy decay characteristics of the cosmic ray neutrons in saline-alkali land from the count rate data; The processing module is also used to determine the absorption effect of salt on the cosmic ray neutrons based on the energy decay characteristics and the salt concentration of the saline-alkali land, and to correct the slowing length when the cosmic ray neutrons collide with water in the saline-alkali land according to the absorption effect, thereby obtaining the distribution of bound water in the saline-alkali land when salt induces the phase transition between free water and bound water. The processing module is also used to measure the temperature of the saline-alkali land at different depths using a temperature sensor, quantify the adsorption intensity of free water at different depths of salt by measuring the trends of all temperature changes and the distribution of bound water, and obtain the adsorption flux of the saline-alkali land. The execution module is used to perform inversion correction on the measured water content of the saline-alkali land based on the adsorption flux to obtain the effective water content of the saline-alkali land.

6. A computer device, characterized in that, The computer device includes a memory and a processor, the memory storing code, and the processor being configured to retrieve the code and execute the method for assessing the water content of saline-alkali land as described in any one of claims 1 to 4.

7. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the method for assessing the water content of saline-alkali land as described in any one of claims 1 to 4.

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