Method, device, equipment and medium for measuring moisture of forest in air

Abstract

The invention discloses a method, a device, equipment and a medium for measuring forest moisture time-air migration, and relates to the technical field of geophysical time-shift resistivity detection.A geophysical resistivity imaging method is utilized, a time dimension is added on the basis of a high-density electrical method, so that the conversion relation between the resistivity and the moisture content of a tree is obtained, and the moisture content of the tree is measured. The resistivity change rate of the tree is inverted according to the resistivity monitoring result, a time-space distribution diagram of the tree moisture is established by combining the conversion relation between the resistivity of the tree and the moisture content, and the change of the tree moisture along with time is judged according to the time-space distribution diagram. According to the time-space transportation change of the forest moisture, the time-space change of the tree moisture is visually obtained through the resistivity change of the trunk moisture and the conversion relation between the resistivity and the moisture content on the whole, the measurement precision of trunk moisture transportation is greatly improved, and guidance is provided for water-saving irrigation and the like in an area.

Description

Technical Field

[0001] The invention relates to the technical field of geophysical time-shift resistivity detection, and in particular to a method, device, equipment and medium for measuring the temporal and spatial migration of forest water. Background Art

[0002] The growth of trees is inseparable from external factors such as light, soil, water, temperature and air quality. Among these conditions, water is an indispensable element for tree growth, and the water requirements of tree growth are complex and diverse. Insufficient irrigation can easily lead to restricted tree growth, poor root development, and reduced fruit and seed yields. However, excessive watering will not only dilute the nutrients in the soil, making it impossible for trees to fully absorb and utilize the required nutrients; at the same time, excessive soil water content will also cause root rot, inhibit root growth, and cause trees to tilt and fall. While doing a good job in afforestation and greening the environment, how to improve the utilization rate of water resources is a major problem. Therefore, it is particularly important to detect and understand the spatiotemporal dynamics of water absorption by trees and water migration in tree trunks.

[0003] In recent decades, the application of geophysical technology in botany has also made remarkable progress. Among them, electrical methods represented by resistivity imaging have achieved significant development due to their advantages of non-destructive dynamic long-term monitoring; ERT has been successfully used to monitor water infiltration, study the water dynamics of crop root zones, and determine tree root distribution; some studies also use electrical methods to describe trunk structure, including separating sapwood and heartwood, evaluating the effects of temperature changes and dehydration on trunks, and detecting wood decay and infection.

[0004] At present, the most common method for measuring water movement in tree trunks is the thermal diffusion method. Its principle is to use a thermal diffusion probe composed of two probes to heat the upper probe, use the lower probe as the reference end, and calculate the sap flow rate by measuring the temperature difference between the two probes. However, this method has high requirements on the accuracy of the measuring equipment and is highly sensitive to the influence of the measuring environment. It can only make point-scale measurements. At the same time, long-term heating will cause certain damage to trees, affecting their normal growth and physiological activities. Therefore, when measuring with the thermal diffusion method, because the two probes are on the same trunk and the influence of the environment on the temperature makes the temperature difference between the two probes relatively small, it is difficult to obtain the sap flow rate on the trunk based on the measured temperature difference. Therefore, the measurement accuracy of water movement in the trunk is relatively low, and it is difficult to provide specific guidance for optimizing irrigation in the region. Summary of the invention

[0005] The embodiments of the present invention provide a method, device, equipment and medium for measuring the spatiotemporal migration of water in forests, which can solve the problem of low measurement accuracy of water migration in tree trunks in the prior art.

[0006] The embodiment of the present invention provides a method for measuring the temporal and spatial migration of forest water, comprising the following steps:

[0007] A power supply electrode array and a measuring electrode array are arranged on the trunk of the tree to be tested, and current is passed between the power supply electrode arrays. The potential difference between the measuring electrode arrays is collected at the same time scale in the rainy season and the dry season with the same number of days under the same electrode array arrangement conditions, and the apparent resistivity value of the trunk in the corresponding period is obtained according to the potential difference;

[0008] According to the apparent resistivity value, the conversion relationship between resistivity and water content is established by using Archie's formula and combining the basic principles of resistivity and water content.

[0009] Using the apparent resistivity value, the water content at different times is obtained according to the conversion relationship and the resistivity at different times is inverted; the resistivity change degree distribution diagram at different times is obtained according to the apparent resistivity value and the inverted resistivity; the apparent resistivity value is adaptively inverted with time constraints according to the resistivity change degree distribution diagram to obtain the resistivity change rate after inversion;

[0010] According to the resistivity change rate, apparent resistivity value and the conversion relationship between resistivity and water content, the spatiotemporal distribution map of tree water content is established, and the spatiotemporal movement of water in the tree trunk is obtained based on the spatiotemporal distribution map.

[0011] Preferably, the arrangement of the power supply electrode array and the measurement electrode array comprises:

[0012] Obtain the soil hydrogeological conditions of the area to be tested;

[0013] According to the soil hydrogeological conditions of the tested area, the wood conditions of the trees in the tested area are analyzed;

[0014] According to the wood conditions of the trees, circular power supply electrode arrays A, B and measuring electrode arrays M, N with the same spacing are arranged on the trunks of the trees to be tested.

[0015] Preferably, the Archie formula is:

[0016] R0=FR w =R w θ -m

[0017] Where: R0 is the resistivity of saturated rock; F is the formation factor; R w is the resistivity of the pore solution; m is the exponential factor; θ is the porosity.

[0018] Preferably, the conversion relationship between resistivity and water content is:

[0019]

[0020] Where:(x,t) is the resistivity of the water-bearing medium at any time t; μ is the calibration constant in the formula; F is the formation factor; P (x,t) is the water content of the solution; ci is the initial water content of ions in the medium voids; ρ ci (x) is the background resistivity value of the aquifer.

[0021] Preferably, in the adaptive time-constrained inversion, the objective function constructed and used is:

[0022]

[0023] in: n i is the spatial model corresponding to the i-th reference event step; t is the number of time steps divided into the entire monitoring process; N is a sparse matrix; k is the number of iterations; is the Lagrange multiplier in the space domain, Λ i is the spatial domain Lagrange multiplier matrix corresponding to the i-th reference time step; is the adaptive time constraint diagonal matrix, A i is the time domain Lagrange multiplier matrix corresponding to the i-th reference time step; d is the observation data corresponding to the reference time step; This is the theoretical calculation result.

[0024] Preferably, the method for obtaining the resistivity change rate after inversion is:

[0025]

[0026] Among them: ρ(x,t) is the percentage change of resistivity at a certain moment, that is, the resistivity change rate; is the resistivity inversion data at time t1; It is the resistivity observation inversion data at time t2.

[0027] The embodiment of the present invention also provides a device for measuring the temporal and spatial migration of forest water, comprising:

[0028] The electrode array module is used to arrange a power supply electrode array and a measuring electrode array on the trunk of the tree to be tested, pass current between the power supply electrode arrays, collect the potential difference between the measuring electrode arrays at the same time scale in the rainy season and the dry season with the same number of days under the same electrode array arrangement conditions, and obtain the apparent resistivity value of the trunk in the corresponding period according to the potential difference;

[0029] The rock physics model module is used to establish the conversion relationship between resistivity and water content based on the apparent resistivity value, using Archie's formula and combining the basic principles of resistivity and water content;

[0030] The time-shift inversion module is used to use the apparent resistivity value to obtain the water content at different times according to the conversion relationship and invert it to obtain the resistivity at different times; obtain the resistivity change degree distribution map at different times according to the apparent resistivity value and the inverted resistivity; perform adaptive time-constrained inversion on the apparent resistivity value according to the resistivity change degree distribution map to obtain the resistivity change rate after inversion;

[0031] The analysis module is used to establish a spatiotemporal distribution diagram of tree water content based on the resistivity change rate, apparent resistivity value and the conversion relationship between resistivity and water content, and obtain the spatiotemporal movement of water in the tree trunk based on the spatiotemporal distribution diagram.

[0032] An embodiment of the present invention further provides an electronic device, including a memory and a processor;

[0033] The memory is used to store computer programs;

[0034] The processor is used to implement the steps of the above-mentioned method for measuring the spatiotemporal migration of forest water when executing the computer program stored in the memory.

[0035] An embodiment of the present invention further provides a computer-readable storage medium for storing a computer program, which, when executed by a processor, implements the steps of the above-mentioned method for measuring the spatiotemporal migration of forest water.

[0036] The embodiment of the present invention provides a method, device, equipment and medium for measuring the temporal and spatial migration of forest water. Compared with the prior art, the advantageous effects thereof are as follows:

[0037] The present invention utilizes geophysical resistivity imaging method, adds a time dimension on the basis of high-density electrical method, establishes the conversion relationship between the resistivity and water content of trees, measures the apparent resistivity value of the trunk at different times and inverts it to obtain the resistivity change rate of the trunk, and combines the resistivity change rate of the trunk with the conversion relationship between resistivity and water content to observe the spatiotemporal migration of water in the trunk. Different from the situation that the temperature difference between electrodes is small and difficult to monitor in the thermal diffusion method, the resistivity change is not affected by the environment and can be measured with an accuracy of one thousandth or one ten-thousandth when measuring the resistivity change. The resistivity change of the trunk can be observed more accurately and then converted into a more accurate change in the water content of the trunk. The measurement is convenient, and thus the measurement accuracy of water migration in the trunk is greatly improved, providing guidance for water-saving irrigation in the region.

[0038] Moreover, compared with the traditional thermal diffusion method, the present invention only needs to set up array-arranged electrodes on the tree trunk, which makes it simple to operate and less affected by environmental factors, while also achieving non-destructive monitoring of trees. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 A schematic diagram of the overall process of a method, device, equipment and medium for measuring the spatiotemporal migration of water in forests provided by an embodiment of the present invention;

[0040] Figure 2 A schematic diagram of the electrode arrangement of a method, device, equipment and medium for measuring the spatiotemporal migration of forest water provided by an embodiment of the present invention;

[0041] Figure 3 A schematic diagram of the moisture concentration distribution of a method, device, equipment and medium for measuring the spatiotemporal migration of forest moisture provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0042] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0043] See also Figures 1 to 3 The embodiment of the present invention provides a method for measuring the temporal and spatial migration of forest water, comprising the following steps:

[0044] Step 1: Measurement preparation: Consult the data and conduct on-site survey to understand the soil, water, temperature and geological conditions of the area to be measured.

[0045] Step 2: Resistivity imaging detection: Perform time-shift electrical detection on the tree trunks in the survey area, collect the apparent resistivity at different times of the day and the apparent resistivity values ​​in the rainy and dry seasons under the same electrode layout conditions. The specific steps are as follows:

[0046] 1. Determine the appropriate electrode array, number of electrodes, lateral line position, and electrode spacing based on the actual conditions of the trees to be tested; select the appropriate electrode spacing based on the initial detection results to ensure that the temporal and spatial changes in the moisture content of the xylem can be fully monitored by the system.

[0047] 2. To monitor the daily variation of moisture in the forest, the measurement is repeated multiple times at different times of the day while keeping the same position and electrode array unchanged. To monitor the seasonal variation of moisture in the tree trunks, multiple measurements are carried out in July, and multiple measurements are carried out in December when there is no rainy season while keeping the same position and electrode array unchanged.

[0048] Step 3: Construct rock physics model: In Archie's formula R0 = FR w =R w θ -m On this basis, the conversion relationship between resistivity and water content is established as follows:

[0049]

[0050] Where: R0 is the resistivity of saturated rock, unit is Ω·m; F is the formation factor, dimensionless; R w is the resistivity of the pore solution, in Ω·m; m is the exponential factor, dimensionless; θ is the porosity.

[0051] ρ (x,t) is the resistivity of the water-bearing medium at any time t, in Ω·m; μ is the calibration constant in the formula, in (mg / L); F is the formation factor, dimensionless; P (x,t) is the water content of the solution, in mg / L; ci is the initial water content of ions in the medium voids, in (mg / L); ρ ci (x) is the background resistivity value of the aquifer, in Ω·m. It is a bridge for studying the water migration process using the resistivity method.

[0052] Step 4: Time-shift inversion: Construct the objective function based on adaptive time-constrained inversion as follows:

[0053]

[0054] in: n i is the spatial model corresponding to the i-th reference event step; t is the number of time steps divided into the entire monitoring process; N is a sparse matrix with only elements 1 or -1 on the diagonal and one sub-diagonal; k is the number of iterations; is the Lagrange multiplier in the space domain, Λ i is the spatial domain Lagrange multiplier matrix corresponding to the i-th reference time step; is the adaptive time constraint diagonal matrix, A i is the time domain Lagrange multiplier matrix corresponding to the i-th reference time that is not long; is the observed data vector, d i is the observation data corresponding to the i-th reference time step; This is the theoretical calculation result.

[0055] The inversion process is further constrained by adding a time smoothness regularization term.

[0056] First, the distribution map of the resistivity change degree compared to the initial resistivity at different spatial positions can be obtained through independent inversion results. Then, according to the size of the distribution map and the existing allocation principle, the Lagrange multiplier can be determined, and the apparent resistivity data detected by resistivity can be adaptively inverted with time constraints.

[0057] Step 5: Based on the formula The resistivity change rate after inversion is calculated, and the spatiotemporal distribution map of moisture content is deduced based on the resistivity detection results and the resistivity-moisture content conversion relationship, thereby inferring the change of tree trunk moisture over time.

[0058] Among them: ρ(x,t) is the percentage change of resistivity at a certain moment (resistivity change rate); is the resistivity inversion data at time t1; It is the resistivity observation inversion data at time t2.

[0059] Embodiment 1:

[0060] Construction preparation: The monitoring area is located in a Zhongshan botanical garden, which has an open terrain and abundant sunshine, which is conducive to the growth of trees. The aeration zone is sticky soil. The monitored objects are pine trees in the area, which are coniferous, with relatively loose wood and good water conductivity. The trunk diameter is about 0.6m.

[0061] 24 brass electrodes, 3 cm long, were arranged along the shape of the tree trunk. The electrodes were inserted into the trunk 1.2 cm, about 4 cm apart, and fixed with binding tapes. The water transport of trees is mainly concentrated in the xylem. The initial resistivity change curve showed that the resistivity was low, indicating that the detection depth reached the xylem at this time.

[0062] In order to monitor the diurnal changes in the spatiotemporal distribution of water migration in tree trunks, resistivity data were collected at 8 a.m. and 9 p.m. from June 5, 2023 to June 11, 2023 using the same Wenner electrode arrangement. According to the data noise estimation in the actual environment, 2% random noise was added to the inversion setting, and inversion was performed based on adaptive time constraints. At the same time, the distribution map of the initial resistivity change degree at different spatial positions was obtained through the inversion results at different time intervals. Taking the initial resistivity change map as an example, the more it leans towards red, the greater the degree of resistivity change, and the more it leans towards blue, the smaller the degree of resistivity change.

[0063] According to the conversion relationship between resistivity and water content, the water content distribution result is inferred, and the temporal and spatial distribution of water in the tree trunk is analyzed by combining the water content distribution map with the resistivity change rate.

[0064] Embodiment 2:

[0065] Construction preparation: The monitoring area is located in a certain Zhongshan Botanical Garden, which has an open terrain and abundant sunshine, which is conducive to the growth of trees, and the aeration zone is sticky soil; the monitored objects are pine trees in the area, which are coniferous, with relatively loose wood and good water conductivity, and the trunk diameter is about 0.6m.

[0066] 24 brass electrodes, 3 cm long, were arranged along the shape of the tree trunk. The electrodes were inserted into the trunk 1.2 cm, about 4 cm apart, and fixed with binding tapes. The water transport of trees is mainly concentrated in the xylem. The initial resistivity change curve showed that the resistivity was low, indicating that the detection depth reached the xylem at this time.

[0067] In order to monitor the seasonal changes in the temporal and spatial distribution of water migration in tree trunks, rainfall was concentrated from 8:00 on July 3 to 0:00 on July 5, with a cumulative rainfall of 15 mm; data were collected every 8 hours from 8:00 a.m. to 5:00 p.m.; from December 5 to December 7, the climate was dry and there was no rainfall, and resistivity data collection was repeated at the same location using the same automatic electrode array method at the same time scale.

[0068] According to the data noise estimation in the actual environment, 2% random noise is added to the inversion setting, and the inversion is performed based on the adaptive time constraint. At the same time, the distribution map of the initial resistivity change degree at different spatial positions is obtained through the inversion results at different time intervals. Taking the initial resistivity change map as an example, the more it leans towards red, the greater the degree of resistivity change, and the more it leans towards blue, the smaller the degree of resistivity change.

[0069] According to the conversion relationship between resistivity and water content, the water content distribution result is inferred, and the temporal and spatial distribution of water in the tree trunk is analyzed by combining the water content distribution map with the resistivity change rate.

[0070] The embodiment of the present invention also provides a device for measuring the temporal and spatial migration of forest water, comprising:

[0071] The electrode array module is used to arrange the power supply electrode array and the measuring electrode array on the trunk of the tree to be tested, pass current between the power supply electrode arrays, collect the potential difference between the measuring electrode arrays at the same time scale in the rainy season and the dry season with the same number of days under the same electrode array layout conditions, and obtain the apparent resistivity value of the trunk in the corresponding period according to the potential difference.

[0072] The rock physics model module is used to establish the conversion relationship between resistivity and water content based on the apparent resistivity value, using Archie's formula and combining the basic principles of resistivity and water content.

[0073] The time-shift inversion module is used to use the apparent resistivity value to obtain the water content at different times according to the conversion relationship and invert it to obtain the resistivity at different times; obtain the resistivity change degree distribution map at different times according to the apparent resistivity value and the inverted resistivity; perform adaptive time-constrained inversion on the apparent resistivity value according to the resistivity change degree distribution map to obtain the resistivity change rate after inversion.

[0074] The analysis module is used to establish a spatiotemporal distribution diagram of tree water content based on the resistivity change rate, apparent resistivity value and the conversion relationship between resistivity and water content, and obtain the spatiotemporal movement of water in the tree trunk based on the spatiotemporal distribution diagram.

[0075] An embodiment of the present invention further provides an electronic device, including a memory and a processor.

[0076] The memory is used to store computer programs.

[0077] When the processor is used to execute the computer program stored in the memory, the steps of the above-mentioned method for measuring the spatiotemporal migration of forest water are implemented.

[0078] An embodiment of the present invention also provides a computer-readable storage medium for storing a computer program, which, when executed by a processor, implements the steps of the above-mentioned method for measuring the spatiotemporal migration of forest water.

[0079] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for measuring the temporal and spatial migration of forest water, characterized in that: The following steps are involved: A power supply electrode array and a measuring electrode array are arranged on the trunk of the tree to be tested, and current is passed between the power supply electrode arrays. The potential difference between the measuring electrode arrays is collected at the same time scale in the rainy season and the dry season with the same number of days under the same electrode array arrangement conditions, and the apparent resistivity value of the trunk in the corresponding period is obtained according to the potential difference; According to the apparent resistivity value, the conversion relationship between resistivity and water content is established by using Archie's formula and combining the basic principles of resistivity and water content. Using the apparent resistivity value, the water content at different times is obtained according to the conversion relationship and the resistivity at different times is inverted; the resistivity change degree distribution diagram at different times is obtained according to the apparent resistivity value and the inverted resistivity; the apparent resistivity value is adaptively inverted with time constraints according to the resistivity change degree distribution diagram to obtain the resistivity change rate after inversion; According to the resistivity change rate, apparent resistivity value and the conversion relationship between resistivity and water content, the spatiotemporal distribution map of tree water content is established, and the spatiotemporal movement of water in the tree trunk is obtained based on the spatiotemporal distribution map.

2. The method for measuring the spatiotemporal migration of forest water according to claim 1, characterized in that: The arrangement of the power supply electrode array and the measurement electrode array comprises: Obtain the soil hydrogeological conditions of the area to be tested; According to the soil hydrogeological conditions of the tested area, the wood conditions of the trees in the tested area are analyzed; According to the wood conditions of the trees, circular power supply electrode arrays A, B and measuring electrode arrays M, N with the same spacing are arranged on the trunks of the trees to be tested.

3. The method for measuring the spatiotemporal movement of forest water according to claim 1, characterized in that: The Archie formula is: R0=FR w =R w i -m Where: R0 is the resistivity of saturated rock; F is the formation factor; R w is the resistivity of the pore solution; m is the exponential factor; θ is the porosity.

4. The method for measuring the temporal and spatial migration of forest water according to claim 1, characterized in that: The conversion relationship between resistivity and water content is: Where: (x,t) is the resistivity of the water-bearing medium at any time t; μ is the calibration constant in the formula; F is the formation factor; P (x,t) is the water content of the solution; ci is the initial water content of ions in the medium voids; ρ ci (x) is the background resistivity value of the aquifer.

5. The method for measuring the temporal and spatial migration of forest water according to claim 1, characterized in that: In the adaptive time-constrained inversion, the objective function constructed and used is: in: n i is the spatial model corresponding to the i-th reference event step, t is the number of time steps divided into the entire monitoring process; N is a sparse matrix; k is the number of iterations; is the Lagrange multiplier in the space domain, Λ i is the spatial domain Lagrange multiplier matrix corresponding to the i-th reference time step; is the adaptive time constraint diagonal matrix, A i is the time domain Lagrange multiplier matrix corresponding to the i-th reference time step; d is the observation data corresponding to the reference time step; This is the theoretical calculation result.

6. The method for measuring the spatiotemporal movement of forest water according to claim 1, characterized in that: The method for obtaining the resistivity change rate after inversion is: Among them: ρ(x,t) is the percentage change of resistivity at a certain moment, that is, the resistivity change rate; is the resistivity inversion data at time t1; It is the resistivity observation inversion data at time t2.

7. A device for measuring the temporal and spatial migration of forest water, characterized in that: include: The electrode array module is used to arrange a power supply electrode array and a measuring electrode array on the trunk of the tree to be tested, pass current between the power supply electrode arrays, collect the potential difference between the measuring electrode arrays at the same time scale in the rainy season and the dry season with the same number of days under the same electrode array arrangement conditions, and obtain the apparent resistivity value of the trunk in the corresponding period according to the potential difference; The rock physics model module is used to establish the conversion relationship between resistivity and water content based on the apparent resistivity value, using Archie's formula and combining the basic principles of resistivity and water content; The time-shift inversion module is used to use the apparent resistivity value to obtain the water content at different times according to the conversion relationship and invert it to obtain the resistivity at different times; obtain the resistivity change degree distribution map at different times according to the apparent resistivity value and the inverted resistivity; perform adaptive time-constrained inversion on the apparent resistivity value according to the resistivity change degree distribution map to obtain the resistivity change rate after inversion; The analysis module is used to establish a spatiotemporal distribution diagram of tree water content based on the resistivity change rate, apparent resistivity value and the conversion relationship between resistivity and water content, and obtain the spatiotemporal movement of water in the tree trunk based on the spatiotemporal distribution diagram.

8. An electronic device, characterized in that: include: Memory and processor; The memory is used to store computer programs; The processor is used to implement the steps of the method for measuring the spatiotemporal migration of forest water as described in any one of claims 1 to 6 when executing the computer program stored in the memory.

9. A computer-readable storage medium, characterized in that: Used to store a computer program, which, when executed by a processor, implements the steps of a method for measuring the spatiotemporal migration of forest water as described in any one of claims 1 to 6.

Images