A method for measuring the saturated hydraulic conductivity of a soil

Abstract

This invention discloses a method for measuring soil saturated hydraulic conductivity, belonging to the field of soil testing. The method involves acquiring remote sensing images of the area to be measured, and collecting vegetation cover data and slope data from these images, while simultaneously collecting ground temperature data in the field. The vegetation cover data, slope data, and ground temperature data are preprocessed to obtain vegetation cover correction factors, slope correction factors, and ground temperature correction factors for the area to be measured. An optimized coefficient for measuring soil saturated hydraulic conductivity is then constructed. This optimized coefficient is used to adjust the baseline value of soil saturated hydraulic conductivity, enabling more accurate measurement of soil saturated hydraulic conductivity and providing more precise guidance for agricultural production.

Description

Technical Field

[0001] This invention relates to soil testing, and more particularly to a method for measuring the saturated hydraulic conductivity of soil. Background Technology

[0002] Saturated hydraulic conductivity is the amount of water that flows through a unit area per unit time under a unit water potential gradient when the soil pores are completely filled with water. It follows Darcy's law, where the water flow is directly proportional to the soil water potential gradient. As a core indicator of soil hydraulic properties, saturated hydraulic conductivity directly affects soil water infiltration and nutrient retention capacity in agricultural production. Both excessively high and low values ​​can negatively impact crop growth. Therefore, measuring soil saturated hydraulic conductivity is a crucial aspect of modern agricultural production. Existing methods for measuring soil saturated hydraulic conductivity, such as CN117309719A, involve placing a soil sample in a measuring device and then adding water to the sample. This existing method is a direct measurement, directly injecting water into the soil sample to measure the saturated hydraulic conductivity. However, because hydraulic conductivity is affected by external factors (such as soil temperature and slope), this method introduces significant errors and cannot provide accurate guidance for agricultural production. Summary of the Invention

[0003] Purpose of the invention: The purpose of this invention is to provide a method for measuring the saturated hydraulic conductivity of soil, so as to solve the problem of large measurement errors in current methods for measuring the saturated hydraulic conductivity of soil.

[0004] Technical Solution: A method for measuring soil saturated hydraulic conductivity, comprising: acquiring remote sensing images of the area to be measured, and collecting vegetation cover data and slope data of the area to be measured from the remote sensing images, while simultaneously collecting ground temperature data of the area to be measured in the field; preprocessing the vegetation cover data, slope data, and ground temperature data obtained from the area to be measured to obtain vegetation cover correction factors, slope correction factors, and ground temperature correction factors; integrating the obtained vegetation cover correction factors, slope correction factors, and ground temperature correction factors to construct an optimized coefficient for measuring soil saturated hydraulic conductivity of the area to be measured; then measuring the soil saturated hydraulic conductivity of the area to be measured, and using the measurement result as a benchmark value for soil saturated hydraulic conductivity of the area to be measured; and finally adjusting the benchmark value for soil saturated hydraulic conductivity using the obtained optimized coefficient for measuring soil saturated hydraulic conductivity to obtain the soil saturated hydraulic conductivity.

[0005] Preferably, when collecting ground temperature data of the area to be measured, several detection points are arbitrarily marked in the area to be measured, and temperature sensors are inserted into each detection point to a depth of 5-10 cm to monitor and collect the temperature. Then, the temperature data of each detection point are summed and averaged to obtain the ground temperature data of the area to be measured.

[0006] Preferably, in constructing the optimized coefficient for soil saturated hydraulic conductivity measurement, the vegetation influence coefficient, slope attenuation coefficient, and water viscosity-temperature coefficient are first obtained based on experimental calibration. Then, by integrating the vegetation cover data, slope data, and ground temperature data obtained from the area to be measured, the vegetation cover correction factor, slope correction factor, and ground temperature correction factor for the area to be measured can be obtained. Finally, by integrating the vegetation cover correction factor, slope correction factor, and ground temperature correction factor, the optimized coefficient for soil saturated hydraulic conductivity measurement of the area to be measured can be obtained. α :

[0007]

[0008] in, k v The vegetation impact coefficient is... C v For vegetation coverage, k This is the slope attenuation coefficient. i For the slope, β The viscosity-temperature coefficient, T 0 The reference temperature for the area to be measured. T It refers to the ground temperature.

[0009] Preferably, the historical annual average temperature of the current measurement area in the season to which the measurement point belongs is obtained, and the historical annual average temperature is combined to obtain the reference temperature of the area to be measured. T 0 :

[0010]

[0011] in, T avg,i The average temperature of the current season for each historical year. T avg,max , T avg,min These are the highest and lowest average temperatures for the current season in historical years, respectively. N This represents the total number of historical years.

[0012] Preferably, the saturated hydraulic conductivity of the soil in the area to be measured is determined by the Philip-Dunne infiltration method or the ring cutter method, and the measurement results are used as the benchmark value of the saturated hydraulic conductivity of the soil in the area to be measured.

[0013] Preferably, when adjusting the benchmark value of soil saturated hydraulic conductivity by optimizing the coefficient through soil saturated hydraulic conductivity measurement, the following applies:

[0014]

[0015] in, K opt For soil saturated hydraulic conductivity, α Optimize the coefficient for measuring soil saturated hydraulic conductivity. K s This is the benchmark value for soil saturated hydraulic conductivity.

[0016] Preferably, vegetation cover data of the area to be measured is obtained from remote sensing images using a pixel decomposition model, and slope data of the area to be measured is obtained from remote sensing images using a digital elevation model.

[0017] Beneficial Effects: This invention, when measuring soil saturated hydraulic conductivity, derives vegetation cover correction factors, slope correction factors, and ground temperature correction factors for the area to be measured, based on the vegetation cover, slope, and ground temperature of the area. These correction factors are then used to construct an optimized soil saturated hydraulic conductivity coefficient. This optimized coefficient is used to adjust the baseline value of soil saturated hydraulic conductivity, thereby enabling more accurate measurements and providing more precise guidance for agricultural production. Furthermore, when obtaining the ground temperature correction factor, it combines the viscosity-temperature coefficient of water from two dimensions: actual ground temperature data measured at several monitoring points in the area to be tested, and the regional reference temperature dynamically obtained from the historical average temperature of the area in the current season at the current measurement time. This makes the ground temperature correction factor more accurate, resulting in a more precise final saturated hydraulic conductivity. Attached Figure Description

[0018] Figure 1 This is a flowchart illustrating the method. Detailed Implementation

[0019] To make the technical solution of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0020] Example

[0021] like Figure 1As shown, a method for measuring soil saturated hydraulic conductivity involves acquiring remote sensing images of the area to be measured, and then obtaining vegetation cover data of the area from the remote sensing images using a pixel decomposition model. C v =0.8 The slope data of the area to be measured, θ=5°, is obtained from remote sensing images using a digital elevation model. Simultaneously, several detection points are arbitrarily marked in the area, and temperature probes are inserted to a depth of 5-10 cm at each point to monitor and collect temperature data. The average of the temperature data from each detection point yields the ground temperature data for the area to be measured. Five detection points are marked in the area, and temperature probes are inserted to a depth of 6 cm at each point. The temperatures detected at each point are then summed: T1=25℃, T2=27℃, T3=23℃, T4=25℃, T5=25℃. T=(T1+T2+T3+T4+T5) / 5=(25+27+23+25+25) / 5=25℃≈298K.

[0022] Then, vegetation influence coefficients were constructed based on the soil hydrological model. k v Objective function:

[0023]

[0024] in, i obs To measure soil moisture, i model These are the simulated values ​​of the hydrological model obtained through the HYDRUS model. C v The vegetation cover is then automatically calibrated using the least squares algorithm via the PEST parameter estimation tool. k v For example, in hilly areas, data from the Sentinel-1 radar and MODIS LAI can be integrated for inversion. k v =0.2 .

[0025] The viscosity μ of water changes with temperature T according to the Arrhenius equation. Therefore, the viscosity of water at different temperatures can be measured using a capillary viscometer or a tuning fork vibrator. m T Fitting ln m T The linear relationship with 1 / T, the slope of which is the viscosity-temperature coefficient β:

[0026]

[0027] At 25℃, μ = 0.89 × 10−3 Pa\cdotps, at 10℃, μ=1.31×10 −3 Pa\cdotps, the viscosity-temperature coefficient β is calculated to be approximately 2400K.

[0028] The landslide stability coefficient K is:

[0029]

[0030] The slope attenuation coefficient k is correlated with the shear strength of the acid-resistant soil. For gentle slopes (θ < 20°): k = 0.2. For steep slopes (θ ≥ 20°): k = 0.3~0.4.

[0031] Then, the vegetation cover data, slope data, and ground temperature data obtained from the area to be measured are preprocessed: the vegetation cover data, slope data, and ground temperature data are combined with the vegetation influence coefficient respectively. k v The vegetation cover correction factor is obtained from the slope attenuation coefficient k and the viscosity-temperature coefficient β. α v Slope correction factor α s and geothermal correction factor α t .

[0032]

[0033]

[0034]

[0035] in, T 0 To obtain the reference temperature for the area to be measured, the historical annual average temperature of the season in which the measurement point is located is obtained, and the historical annual average temperature is combined to obtain the reference temperature for the area to be measured. T 0 :

[0036]

[0037] in, T avg,i The average temperature of the current season for each historical year. T avg,max , T avg,min These are the highest and lowest average temperatures for the current season in historical years, respectively. NThis represents the total number of historical years. For example, if the current measurement point falls in spring, the average temperature of the area to be measured each spring for the past 5 years is obtained: 18℃, 21℃, 20℃, 22℃, and 19℃. From this, the reference temperature of the area to be measured at the current measurement point can be obtained. T 0 =20℃≈293k Therefore, the vegetation cover correction factor can be obtained. α v Slope correction factor α s and geothermal correction factor α t They are respectively:

[0038] α v =1+0.2·ln(1+0.8)≈1.12 .

[0039] α s =cos 0.2 (5°)≈0.99 .

[0040] α t =e 2400(1 / 293-1 / 298) ≈1.25 .

[0041] The obtained vegetation cover correction factor, slope correction factor, and ground temperature correction factor are then integrated to construct the optimized coefficient for measuring the soil saturated hydraulic conductivity of the area to be measured. α=α v ·α s ·α t =1.12×1.25×0.99≈1.39 Then, the saturated hydraulic conductivity of the soil in the area to be measured was determined using the Philip-Dunne infiltration method or the ring sampler method (the saturated hydraulic conductivity of the soil measured by the ring sampler method was 10 cm / hr), and the measurement results were used as the benchmark value of the saturated hydraulic conductivity of the soil in the area to be measured. K s Then, by adjusting the benchmark value of soil saturated hydraulic conductivity using the obtained soil saturated hydraulic conductivity measurement optimization coefficient, the soil saturated hydraulic conductivity can be obtained. K opt for:

[0042] K opt =α·K s =1.39×10=13.9 cm / hr.

[0043] Compared to traditional direct measurement methods, this method comprehensively considers the factors affecting soil saturation rate and uses them as optimization coefficients to optimize the measured value of soil saturated hydraulic conductivity, thereby obtaining a more accurate soil saturation rate and providing more precise guidance for agricultural production.

[0044] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for measuring the saturated hydraulic conductivity of soil, characterized in that, include: Acquire remote sensing images of the area to be measured, and collect vegetation cover data and slope data of the area to be measured from the remote sensing images. At the same time, collect ground temperature data of the area to be measured in the field. Preprocessing the vegetation cover data, slope data, and ground temperature data obtained from the area to be measured allows us to obtain the vegetation cover correction factor, slope correction factor, and ground temperature correction factor for the area to be measured. By integrating the obtained vegetation cover correction factor, slope correction factor, and ground temperature correction factor, an optimized coefficient for measuring the soil saturated hydraulic conductivity of the area to be measured can be constructed. Then, the soil saturated hydraulic conductivity of the area to be measured is determined, and the measurement result is used as the benchmark value of the soil saturated hydraulic conductivity of the area to be measured. The benchmark value of the soil saturated hydraulic conductivity is then adjusted by the obtained optimized coefficient for measuring the soil saturated hydraulic conductivity, thereby obtaining the soil saturated hydraulic conductivity. When collecting ground temperature data of the area to be measured, several detection points are randomly marked in the area to be measured, and temperature probes are inserted into each detection point to a depth of 5-10cm to monitor and collect the temperature. Then, the temperature data of each detection point are summed and averaged to obtain the ground temperature data of the area to be measured. In constructing the optimized coefficient for soil saturated hydraulic conductivity measurement, the vegetation influence coefficient, slope attenuation coefficient, and water viscosity-temperature coefficient are first obtained based on experimental calibration. Then, by integrating the vegetation cover data, slope data, and ground temperature data obtained from the area to be measured, the vegetation cover correction factor, slope correction factor, and ground temperature correction factor for the area to be measured can be obtained. Finally, by integrating the vegetation cover correction factor, slope correction factor, and ground temperature correction factor, the optimized coefficient for soil saturated hydraulic conductivity measurement in the area to be measured can be obtained. α : ,in, k v The vegetation impact coefficient is... C v For vegetation coverage, k This is the slope attenuation coefficient. θ For the slope, β The viscosity-temperature coefficient, T 0 The reference temperature for the area to be measured. T Ground temperature; By obtaining the historical annual average temperature of the current measurement area for the season in which the measurement point is located, and combining the historical annual average temperatures, a reference temperature for the area to be measured can be obtained. T 0 : ,in, T avg,i The average temperature of the current season for each historical year. T avg,max , T avg,min These are the highest and lowest average temperatures for the current season in historical years, respectively. N Total number of historical years; When adjusting the benchmark value of soil saturated hydraulic conductivity by optimizing the coefficient through soil saturated hydraulic conductivity measurement, we have: ,in, K opt For soil saturated hydraulic conductivity, α Optimize the coefficient for measuring soil saturated hydraulic conductivity. K s This is the benchmark value for soil saturated hydraulic conductivity.

2. The method for measuring soil saturated hydraulic conductivity according to claim 1, characterized in that, The saturated hydraulic conductivity of the soil in the area to be measured was determined using the Philip-Dunne infiltration method or the ring cutter method, and the results were used as the benchmark value for the saturated hydraulic conductivity of the soil in the area to be measured.

3. The method for measuring soil saturated hydraulic conductivity according to claim 1, characterized in that, The vegetation cover data of the area to be measured is obtained from the remote sensing image using the pixel decomposition model method, and the slope data of the area to be measured is obtained from the remote sensing image using the digital elevation model.

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