A method for monitoring soil erosion rate in wind-water combined erosion areas

Abstract

The invention discloses a soil erosion rate monitoring method for a wind-water composite erosion area, which belongs to the field of soil erosion rate monitoring. The method comprises dividing a soil erosion monitoring area into a bare area and a vegetation-covered area based on the surface coverage, performing grid division, obtaining soil erosion resistance of each grid in the bare area and the vegetation-covered area; obtaining a reference grid in the bare area and a reference grid in the vegetation-covered area; obtaining image data at the start and end time of monitoring in the bare area and image data at the start and end time of monitoring in the vegetation-covered area; calculating the soil erosion amount of the reference grid in the bare area and the soil erosion amount of the reference grid in the vegetation-covered area; calculating the soil erosion amount corrected by the participation of soil erosion resistance; calculating the soil erosion rate according to the soil erosion amount corrected by the participation of soil erosion resistance, and completing soil erosion rate monitoring in a wind-water composite erosion area. The invention solves the problem that the workload and monitoring accuracy of the existing monitoring method cannot be balanced.

Description

Technical Field

[0001] The invention belongs to the field of soil erosion rate monitoring, and in particular relates to a soil erosion rate monitoring method in a wind-water composite erosion area. Background Art

[0002] Wind-water compound erosion refers to the joint and alternating effects of wind and water on the same erosion object. In essence, it is the transportation and deposition of surface materials by one erosion force, which prepares the material basis for the further action of another erosion force and the process of reshaping the existing erosion landform.

[0003] In arid and semi-arid areas, wind erosion and water erosion often occur simultaneously or alternately, forming a unique wind-water compound erosion. The two are mutually causal, alternating in time and staggered in space. Soil erosion leads to land degradation and reduced productivity, seriously affecting agricultural production and ecosystem stability.

[0004] Due to the complexity and severity of wind-water compound erosion, quantitative research and monitoring are particularly important, which helps to understand the dynamic changes of the erosion process, evaluate the impact of erosion on the environment and ecology, and provide a scientific basis for formulating effective prevention and control measures.

[0005] Existing monitoring methods include water measurement, volume measurement, hydrological measurement and erosion needle method. Specifically, the water measurement method directly observes the elevation changes of microtopography through a set of fixed marks, thereby determining the rate at which the soil profile is eroded, realizing direct observation of the erosion rate, and the results are intuitive, but the workload is large and is greatly affected by human factors. The volumetric measurement method calculates the amount of erosion through the changes in the longitudinal and cross-sectional sections of rills, shallow gullies and cut gullies. This method is suitable for monitoring gully erosion and can accurately reflect the amount of gully erosion, but the operation is relatively complicated. The hydrological measurement method measures the amount of sediment deposition in the reservoir and calculates it in combination with the sediment transport ratio. This method can indirectly reflect the soil erosion situation and is suitable for monitoring at the basin scale, but the influencing factors of soil erosion are not fully considered and the influence of other factors is ignored. The erosion needle method calculates the soil erosion rate by setting fixed marks (such as erosion needles) on the ground and regularly measuring the changes in their height above the ground. This method is simple and easy to operate with low cost, but may be affected by human destruction or natural factors. Summary of the invention

[0006] In view of the above-mentioned deficiencies in the prior art, the present invention provides a soil erosion rate monitoring method in a wind-water composite erosion area, which solves the problem that the workload and monitoring accuracy of the prior monitoring methods cannot be balanced.

[0007] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention is: a method for monitoring soil erosion rate in a wind-water composite erosion area, comprising the following steps:

[0008] S1. Determine the soil erosion monitoring area;

[0009] S2. At the beginning of monitoring, the soil erosion monitoring area is divided into bare areas and vegetation-covered areas based on the surface coverage. The bare areas and vegetation-covered areas are divided into grids respectively, and the soil is randomly sampled in each grid to obtain the soil erosion resistance of each grid in the bare area and vegetation-covered area;

[0010] S3. According to the soil erosion resistance of each grid in the bare area and the vegetation-covered area, the grid with the largest soil erosion resistance in the bare area and the grid with the largest soil erosion resistance in the vegetation-covered area are respectively used as reference grids to obtain the bare area reference grid and the vegetation-covered area reference grid, and erosion pins are respectively inserted on the bare area reference grid and the vegetation-covered area reference grid;

[0011] S4. Using a drone to obtain image data of the soil erosion monitoring area at the start and end times of monitoring, and segmenting the image data of the soil erosion monitoring area at the start and end times of monitoring based on the exposed area and the vegetation covered area, respectively obtaining image data at the start and end times of monitoring of the exposed area and image data at the start and end times of monitoring of the vegetation covered area;

[0012] S5. Calculate the soil erosion amount of the bare area reference grid and the soil erosion amount of the vegetation covered area reference grid respectively according to the erosion pins in the bare area reference grid and the vegetation covered area reference grid;

[0013] S6. Calculate the amount of soil erosion corrected by soil erosion resistance based on the image data at the start and end times of monitoring in the bare area, the image data at the start and end times of monitoring in the vegetation covered area, the amount of soil erosion of the reference grid in the bare area, and the amount of soil erosion of the reference grid in the vegetation covered area;

[0014] S7. Calculate the soil erosion rate based on the soil erosion amount corrected by soil erosion resistance, and complete the soil erosion rate monitoring in the wind-water combined erosion area.

[0015] Furthermore, the S2 is specifically:

[0016] S201. At the beginning of monitoring, the soil erosion monitoring area is divided into a bare area and a vegetation covered area based on the surface coverage;

[0017] S202, respectively setting grid division widths for the exposed area and the vegetation-covered area, and performing grid division based on the set grid division widths for the exposed area and the vegetation-covered area, to obtain grid division results for the exposed area and the vegetation-covered area;

[0018] S203. According to the grid division results of the bare area and the grid division results of the vegetation covered area, randomly sample the soil in each grid, and calculate the soil erosion resistance of each grid in the bare area and the vegetation covered area.

[0019] Furthermore, the expressions for calculating the soil erosion resistance of each grid in the bare area and the vegetation covered area in S203 are respectively:

[0020]

[0021] Among them, Soil s is the soil erosion resistance of each grid in the exposed area; Soil is the soil erosion resistance of the i-th grid in the exposed area; c is the soil erosion resistance of each grid in the vegetation coverage area; is the soil erosion resistance of the jth grid in the vegetation coverage area; is the soil erosion resistance of the grid; γ1 is the water erosion weight coefficient; N soil is the total number of soil particles sampled; N scat is the number of collapsed soil particles after water action; γ2 is the wind erosion weight coefficient; F(f,soil) is the number of soil particles separated under the action of wind force f; N is the number of sampling times; ty is the area identifier of the grid; s is the bare area identifier; c is the vegetation covered area identifier; r is the grid number identifier; i is the bare area grid number; j is the vegetation covered area grid number; f1 is the probability of occurrence of the first wind intensity in the soil erosion monitoring area; is the number of soil particles separated under the first wind intensity; f2 is the occurrence probability of the second wind intensity in the soil erosion monitoring area; is the number of soil particles separated under the second wind intensity; f max is the probability of occurrence of the maximum wind intensity in the soil erosion monitoring area; is the number of soil particles separated under the max-th wind intensity; max is the maximum wind intensity level during the data collection period in the soil erosion monitoring area.

[0022] Furthermore, the S6 is specifically:

[0023] S601, grayscale processing is performed on the image data at the start and end time of monitoring the exposed area and the image data at the start and end time of monitoring the vegetation covered area to obtain grayscale images at the start and end time of monitoring the exposed area and grayscale images at the start and end time of monitoring the vegetation covered area;

[0024] S602, according to the grayscale image at the start time of the exposed area monitoring and the grayscale image at the end time of the exposed area monitoring, the average grayscale value of the grid at the start time is subtracted from the average grayscale value of the grid at the end time to obtain the grayscale difference of each grid in the exposed area;

[0025] S603, according to the grayscale image at the start time of the vegetation coverage area monitoring and the grayscale image at the end time of the vegetation coverage area monitoring, the average grayscale value of the grid at the start time is subtracted from the average grayscale value of the grid at the end time to obtain the grayscale difference of each grid in the vegetation coverage area;

[0026] S604, according to the grayscale difference of each grid in the bare area and the grayscale difference of each grid in the vegetation covered area, respectively obtain the grayscale difference of the reference grid in the bare area and the grayscale difference of the reference grid in the vegetation covered area, and according to the soil erosion amount of the reference grid in the bare area, the soil erosion amount of the reference grid in the vegetation covered area, the grayscale difference of the reference grid in the bare area, and the grayscale difference of the reference grid in the vegetation covered area, calculate the soil erosion amount of a single grayscale value change;

[0027] S605. Calculate the soil erosion amount corrected by soil erosion resistance according to the soil erosion amount of the single gray value change, the gray value difference of each grid in the exposed area, and the gray value difference of each grid in the vegetation covered area.

[0028] Furthermore, the expression for calculating the soil erosion amount of a single gray value change in S604 is:

[0029]

[0030] Among them, E s A is the soil erosion amount of the single gray value change in the exposed area; s,O H is the soil erosion amount of the reference grid in the exposed area; s,O is the grayscale difference of the reference grid in the exposed area; E c A is the soil erosion amount of a single gray value change in the vegetation coverage area; c,O is the soil erosion amount of the reference grid in the vegetation coverage area; H c,O It is the grayscale difference of the reference grid in the vegetation coverage area.

[0031] Furthermore, the expression for calculating the soil erosion amount corrected by the soil erosion resistance in S605 is:

[0032]

[0033] Among them, A is the amount of soil erosion corrected by soil erosion resistance; H s,i is the grayscale difference of the ith grid in the exposed area; E s is the soil erosion amount of the single gray value change in the exposed area; is the soil erosion resistance of the i-th grid in the bare area; H is the soil erosion resistance of the reference grid in the exposed area; c,j is the grayscale difference of the jth grid in the vegetation coverage area; E c is the soil erosion amount of the single gray value change in the vegetation coverage area; is the soil erosion resistance of the jth grid in the vegetation coverage area; Soil erosion resistance of the reference grid for the vegetation cover area.

[0034] The beneficial effects of the present invention are as follows: the present invention combines the traditional monitoring method with the modern monitoring method, establishes standards through soil erosion resistance, takes the reference grid as a benchmark, calculates the soil erosion amount on the reference grid using the traditional monitoring method, and calculates the overall soil erosion amount based on the soil erosion amount of the reference grid, thereby improving the accuracy of the method while ensuring the calculation speed; similarly, based on the soil erosion resistance of the grid, corrections are made based on the reference grid, thereby improving the accuracy of the method. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 The figure is a flow chart of the method of the present invention. DETAILED DESCRIPTION

[0036] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0037] like Figure 1 As shown, in one embodiment of the present invention, a method for monitoring soil erosion rate in a wind-water combined erosion area comprises the following steps:

[0038] S1. Determine the soil erosion monitoring area;

[0039] S2. At the beginning of monitoring, the soil erosion monitoring area is divided into bare areas and vegetation-covered areas based on the surface coverage. The bare areas and vegetation-covered areas are divided into grids respectively, and the soil is randomly sampled in each grid to obtain the soil erosion resistance of each grid in the bare area and vegetation-covered area;

[0040] S3. According to the soil erosion resistance of each grid in the bare area and the vegetation-covered area, the grid with the largest soil erosion resistance in the bare area and the grid with the largest soil erosion resistance in the vegetation-covered area are respectively used as reference grids to obtain the bare area reference grid and the vegetation-covered area reference grid, and erosion pins are respectively inserted on the bare area reference grid and the vegetation-covered area reference grid;

[0041] S4. Using a drone to obtain image data of the soil erosion monitoring area at the start and end times of monitoring, and segmenting the image data of the soil erosion monitoring area at the start and end times of monitoring based on the exposed area and the vegetation covered area, respectively obtaining image data at the start and end times of monitoring of the exposed area and image data at the start and end times of monitoring of the vegetation covered area;

[0042] S5. Calculate the soil erosion amount of the bare area reference grid and the soil erosion amount of the vegetation covered area reference grid respectively according to the erosion pins in the bare area reference grid and the vegetation covered area reference grid;

[0043] S6. Calculate the amount of soil erosion corrected by soil erosion resistance based on the image data at the start and end times of monitoring in the bare area, the image data at the start and end times of monitoring in the vegetation covered area, the amount of soil erosion of the reference grid in the bare area, and the amount of soil erosion of the reference grid in the vegetation covered area;

[0044] S7. Calculate the soil erosion rate based on the soil erosion amount corrected by soil erosion resistance, and complete the soil erosion rate monitoring in the wind-water combined erosion area.

[0045] In this embodiment, the criterion for dividing the bare area and the vegetation covered area is whether the ground is bare.

[0046] The S2 is specifically:

[0047] S201. At the beginning of monitoring, the soil erosion monitoring area is divided into a bare area and a vegetation covered area based on the surface coverage;

[0048] S202, respectively setting grid division widths for the exposed area and the vegetation-covered area, and performing grid division based on the set grid division widths for the exposed area and the vegetation-covered area, to obtain grid division results for the exposed area and the vegetation-covered area;

[0049] S203. According to the grid division results of the bare area and the grid division results of the vegetation covered area, randomly sample the soil in each grid, and calculate the soil erosion resistance of each grid in the bare area and the vegetation covered area.

[0050] The expressions for calculating the soil erosion resistance of each grid in the bare area and the vegetation covered area in S203 are respectively:

[0051]

[0052] Among them, Soil s is the soil erosion resistance of each grid in the exposed area; Soil is the soil erosion resistance of the i-th grid in the exposed area; c is the soil erosion resistance of each grid in the vegetation coverage area; is the soil erosion resistance of the jth grid in the vegetation coverage area; is the soil erosion resistance of the grid; γ1 is the water erosion weight coefficient; N soil is the total number of soil particles sampled; N scat is the number of collapsed soil particles after water action; γ2 is the wind erosion weight coefficient; F(f,soil) is the number of soil particles separated under the action of wind force f; N is the number of sampling times; ty is the area identifier of the grid; s is the bare area identifier; c is the vegetation covered area identifier; r is the grid number identifier; i is the bare area grid number; j is the vegetation covered area grid number; f1 is the probability of occurrence of the first wind intensity in the soil erosion monitoring area; is the number of soil particles separated under the first wind intensity; f2 is the occurrence probability of the second wind intensity in the soil erosion monitoring area; is the number of soil particles separated under the second wind intensity; f max is the probability of occurrence of the maximum wind intensity in the soil erosion monitoring area; is the number of soil particles separated under the max-th wind intensity; max is the maximum wind intensity level during the data collection period in the soil erosion monitoring area.

[0053] In this embodiment, when performing grid division, some areas have widths and lengths that are smaller than the grid division width and can be treated as a single grid; if the width is smaller than the grid division width and the length is larger than the grid division width, the length is used as the division direction.

[0054] In this embodiment, wind intensity is obtained based on historical wind monitoring data in the soil erosion monitoring area: a level interval of wind intensity is set, the wind intensity is divided based on the level interval, and the occurrence probability of each wind intensity is counted; the first wind intensity to the maximum wind intensity are sorted based on the wind size.

[0055] The S6 is specifically:

[0056] S601, grayscale processing is performed on the image data at the start and end time of monitoring the exposed area and the image data at the start and end time of monitoring the vegetation covered area to obtain grayscale images at the start and end time of monitoring the exposed area and grayscale images at the start and end time of monitoring the vegetation covered area;

[0057] S602, according to the grayscale image at the start time of the exposed area monitoring and the grayscale image at the end time of the exposed area monitoring, the average grayscale value of the grid at the start time is subtracted from the average grayscale value of the grid at the end time to obtain the grayscale difference of each grid in the exposed area;

[0058] S603, according to the grayscale image at the start time of the vegetation coverage area monitoring and the grayscale image at the end time of the vegetation coverage area monitoring, the average grayscale value of the grid at the start time is subtracted from the average grayscale value of the grid at the end time to obtain the grayscale difference of each grid in the vegetation coverage area;

[0059] S604, according to the grayscale difference of each grid in the bare area and the grayscale difference of each grid in the vegetation covered area, respectively obtain the grayscale difference of the reference grid in the bare area and the grayscale difference of the reference grid in the vegetation covered area, and according to the soil erosion amount of the reference grid in the bare area, the soil erosion amount of the reference grid in the vegetation covered area, the grayscale difference of the reference grid in the bare area, and the grayscale difference of the reference grid in the vegetation covered area, calculate the soil erosion amount of a single grayscale value change;

[0060] S605. Calculate the soil erosion amount corrected by soil erosion resistance according to the soil erosion amount of the single gray value change, the gray value difference of each grid in the exposed area, and the gray value difference of each grid in the vegetation covered area.

[0061] The expression for calculating the soil erosion amount of a single gray value change in S604 is:

[0062]

[0063] Among them, E s A is the soil erosion amount of the single gray value change in the exposed area; s,O H is the soil erosion amount of the reference grid in the exposed area; s,O is the grayscale difference of the reference grid in the exposed area; E c A is the soil erosion amount of a single gray value change in the vegetation coverage area; c,O is the soil erosion amount of the reference grid in the vegetation coverage area; H c,O It is the grayscale difference of the reference grid in the vegetation coverage area.

[0064] The expression for calculating the soil erosion amount corrected by the soil erosion resistance in S605 is:

[0065]

[0066] Among them, A is the amount of soil erosion corrected by soil erosion resistance; H s,i is the grayscale difference of the ith grid in the exposed area; E s is the soil erosion amount of the single gray value change in the exposed area; is the soil erosion resistance of the i-th grid in the bare area; H is the soil erosion resistance of the reference grid in the exposed area; c,j is the grayscale difference of the jth grid in the vegetation coverage area; E c is the soil erosion amount of the single gray value change in the vegetation coverage area; is the soil erosion resistance of the jth grid in the vegetation coverage area; Soil erosion resistance of the reference grid for the vegetation cover area.

[0067] In this embodiment, since the soil erosion amount within the grayscale unit change under different soil erosion resistance is different, it cannot be directly calculated based on the "soil erosion amount of a single grayscale value change" calculated based on the reference grid, and the error is too large. Adding the soil erosion resistance of each grid for correction can improve the calculation accuracy.

Claims

1. A soil erosion rate monitoring method in a wind-water combined erosion area, characterized in that: The following steps are involved: S1. Determine the soil erosion monitoring area; S2. At the beginning of monitoring, the soil erosion monitoring area is divided into bare areas and vegetation-covered areas based on the surface coverage. The bare areas and vegetation-covered areas are divided into grids respectively, and the soil is randomly sampled in each grid to obtain the soil erosion resistance of each grid in the bare area and vegetation-covered area; S3. According to the soil erosion resistance of each grid in the bare area and the vegetation-covered area, the grid with the largest soil erosion resistance in the bare area and the grid with the largest soil erosion resistance in the vegetation-covered area are respectively used as reference grids to obtain the bare area reference grid and the vegetation-covered area reference grid, and erosion pins are respectively inserted on the bare area reference grid and the vegetation-covered area reference grid; S4. Using a drone to obtain image data of the soil erosion monitoring area at the start and end times of monitoring, and segmenting the image data of the soil erosion monitoring area at the start and end times of monitoring based on the exposed area and the vegetation covered area, respectively obtaining image data at the start and end times of monitoring of the exposed area and image data at the start and end times of monitoring of the vegetation covered area; S5. Calculate the soil erosion amount of the bare area reference grid and the soil erosion amount of the vegetation covered area reference grid respectively according to the erosion pins in the bare area reference grid and the vegetation covered area reference grid; S6, calculating the soil erosion amount corrected by soil erosion resistance according to the image data at the start and end time of monitoring of the bare area, the image data at the start and end time of monitoring of the vegetation covered area, the soil erosion amount of the reference grid of the bare area, and the soil erosion amount of the reference grid of the vegetation covered area; S6 is specifically: S601, grayscale processing is performed on the image data at the start and end time of monitoring the exposed area and the image data at the start and end time of monitoring the vegetation covered area to obtain grayscale images at the start and end time of monitoring the exposed area and grayscale images at the start and end time of monitoring the vegetation covered area; S602, according to the grayscale image at the start time of the exposed area monitoring and the grayscale image at the end time of the exposed area monitoring, the average grayscale value of the grid at the start time is subtracted from the average grayscale value of the grid at the end time to obtain the grayscale difference of each grid in the exposed area; S603, according to the grayscale image at the start time of the vegetation coverage area monitoring and the grayscale image at the end time of the vegetation coverage area monitoring, the average grayscale value of the grid at the start time is subtracted from the average grayscale value of the grid at the end time to obtain the grayscale difference of each grid in the vegetation coverage area; S604, according to the grayscale difference of each grid in the bare area and the grayscale difference of each grid in the vegetation covered area, the grayscale difference of the reference grid in the bare area and the grayscale difference of the reference grid in the vegetation covered area are obtained respectively, and the soil erosion amount of the reference grid in the bare area, the soil erosion amount of the reference grid in the vegetation covered area, the grayscale difference of the reference grid in the bare area and the grayscale difference of the reference grid in the vegetation covered area are calculated; the expression for calculating the soil erosion amount of the single grayscale value change in S604 is: Among them, E s A is the soil erosion amount of the single gray value change in the exposed area; s,O H is the soil erosion amount of the reference grid in the exposed area; s,O is the grayscale difference of the reference grid in the exposed area; E c A is the soil erosion amount of a single gray value change in the vegetation coverage area; c,O is the soil erosion amount of the reference grid in the vegetation coverage area; H c,O is the grayscale difference of the reference grid in the vegetation coverage area; S605, calculating the soil erosion amount corrected by soil erosion resistance according to the soil erosion amount of the single gray value change, the gray difference of each grid in the bare area and the gray difference of each grid in the vegetation covered area; the expression for calculating the soil erosion amount corrected by soil erosion resistance in S605 is: Among them, A is the amount of soil erosion corrected by soil erosion resistance; H s,i is the grayscale difference of the ith grid in the exposed area; E s is the soil erosion amount of the single gray value change in the exposed area; is the soil erosion resistance of the i-th grid in the bare area; H is the soil erosion resistance of the reference grid in the exposed area; c,j is the grayscale difference of the jth grid in the vegetation coverage area; E c is the soil erosion amount of the single gray value change in the vegetation coverage area; is the soil erosion resistance of the jth grid in the vegetation coverage area; Soil erosion resistance of the reference grid for the vegetation cover area; S7. Calculate the soil erosion rate based on the soil erosion amount corrected by soil erosion resistance, and complete the soil erosion rate monitoring in the wind-water combined erosion area.

2. The soil erosion rate monitoring method in the wind-water combined erosion area according to claim 1 is characterized in that: The S2 is specifically: S201. At the beginning of monitoring, the soil erosion monitoring area is divided into a bare area and a vegetation covered area based on the surface coverage; S202, respectively setting grid division widths for the exposed area and the vegetation-covered area, and performing grid division based on the set grid division widths for the exposed area and the vegetation-covered area, to obtain grid division results for the exposed area and the vegetation-covered area; S203. According to the grid division results of the bare area and the grid division results of the vegetation covered area, randomly sample the soil in each grid, and calculate the soil erosion resistance of each grid in the bare area and the vegetation covered area.

3. The soil erosion rate monitoring method in the wind-water combined erosion area according to claim 2 is characterized in that: The expressions for calculating the soil erosion resistance of each grid in the bare area and the vegetation covered area in S203 are respectively: Among them, Soil s is the soil erosion resistance of each grid in the exposed area; Soil is the soil erosion resistance of the i-th grid in the exposed area; c is the soil erosion resistance of each grid in the vegetation coverage area; is the soil erosion resistance of the jth grid in the vegetation coverage area; is the soil erosion resistance of the grid; γ1 is the water erosion weight coefficient; N soil is the total number of soil particles sampled; N scat is the number of collapsed soil particles after water action; γ2 is the wind erosion weight coefficient; F(f,soil) is the number of soil particles separated under the action of wind force f; N is the number of sampling times; ty is the area identifier of the grid; s is the bare area identifier; c is the vegetation covered area identifier; r is the grid number identifier; i is the bare area grid number; j is the vegetation covered area grid number; f1 is the probability of occurrence of the first wind intensity in the soil erosion monitoring area; is the number of soil particles separated under the first wind intensity; f2 is the occurrence probability of the second wind intensity in the soil erosion monitoring area; is the number of soil particles separated under the second wind intensity; f max is the probability of occurrence of the maximum wind intensity in the soil erosion monitoring area; is the number of soil particles separated under the max-th wind intensity; max is the maximum wind intensity level during the data collection period in the soil erosion monitoring area.

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