Soil erosion risk assessment method based on soil erosion occurrence probability

Abstract

The present invention provides a soil erosion risk assessment method based on the probability of soil erosion occurrence, comprising the following steps: first, data preprocessing: aligning precipitation data, NDVI data, DEM data, land use data, and soil data acquired in the study area in projection and coordinate systems; second, preparing a multi-year soil erosion modulus distribution map for the study area based on the data; third, obtaining the multi-year soil erosion intensity and the frequency of occurrence of different soil erosion intensities in the study area based on the soil erosion modulus distribution map; and fourth, assessing the soil erosion risk in the study area. The soil erosion risk assessment method provided by the present invention combines the soil erosion intensity grade and the probability of soil erosion occurrence to obtain the expected value after soil erosion occurs, overcoming the shortcomings of previous soil erosion risk assessments that directly use soil erosion volume or soil erosion intensity instead of soil erosion risk without considering the probability of soil erosion occurrence.

Description

Technical Field

[0001] The present invention belongs to the technical field of soil erosion remote sensing monitoring, and in particular relates to a soil erosion risk assessment method based on soil erosion occurrence probability. Background Art

[0002] The Universal Soil Loss Equation (RUSLE) comprehensively considers the natural factors that influence soil erosion, quantitatively calculating soil erosion using factors such as rainfall erosivity, soil erodibility, slope gradient and length, crop cover, and soil and water conservation measures. The RUSLE is highly practical and has been widely adopted worldwide. However, since the RUSLE calculates the amount of soil loss in a specific area over a specific period of time, it does not represent the local soil loss risk. Therefore, the probability of soil erosion occurring over a long time series in the area needs to be considered when assessing soil loss risk.

[0003] In existing soil erosion risk assessments, researchers typically use two methods. One method uses the soil erosion modulus calculated from the universal soil erosion equation combined with the soil erosion intensity defined in the Soil Erosion Classification and Grading Standard to describe the soil erosion risk of a study area. The other method uses a combination of soil properties, topography, and vegetation types in the study area, assigning them different scores through expert scoring or other methods, and then overlaying these scores to determine the soil erosion risk of the study area.

[0004] Both of the aforementioned soil erosion risk assessment methods have shortcomings. The first method directly considers the amount or intensity of soil erosion as soil erosion risk, ignoring the difference between soil erosion risk and the amount or intensity of soil erosion. While the second method can determine soil erosion risk, its assignment is highly subjective and therefore subject to error. Furthermore, both methods ignore the impact of the probability of soil erosion on soil erosion risk.

[0005] Based on the above background, the present invention provides a soil erosion risk assessment method that combines soil erosion intensity and soil erosion occurrence probability. Summary of the Invention

[0006] The purpose of this invention is to address the deficiencies of the existing technology and provide a soil erosion risk assessment method based on the probability of soil erosion occurrence. The specific scheme is as follows:

[0007] A soil erosion risk assessment method based on soil erosion occurrence probability, characterized by comprising the following steps:

[0008] Step 1: Data preprocessing: align the precipitation data, NDVI data, DEM data, land use data, and soil data obtained in the study area in the projection and coordinate system;

[0009] Step 2: Prepare a multi-year soil erosion modulus distribution map of the study area based on the data obtained in step 1, which includes the following steps:

[0010] A. Obtain the rainfall erosivity factor R, slope length factor LS, soil erodibility factor K, vegetation cover factor C, and soil and water conservation measures factor P layers for the study area based on precipitation data, NDVI data, DEM data, land use data, and soil data;

[0011] B. Calculate the soil erosion modulus of the study area using the RUSLE equation based on the obtained factor layers.

[0012] A=R·K·L·S·C·P

[0013] Where A is the annual soil erosion modulus, unit is t / (km 2 y);

[0014] Step 3: Obtain the multi-year soil erosion intensity and the occurrence probability of different soil erosion intensities in the study area based on the soil erosion modulus distribution map prepared in step 2, which includes the following steps:

[0015] A. According to the soil erosion intensity classification standard in the soil erosion classification standard SL190-2007, the multi-year soil erosion intensity in the study area is divided into different levels ω i ;

[0016] B. Calculate the probability f of different soil erosion intensities in a single pixel based on the obtained soil erosion intensity results over many years. i ;

[0017] Step 4: Assess soil erosion risk in the study area, which includes the following steps:

[0018] A. Soil erosion risk is defined as the expected value after soil erosion occurs. For a single pixel, soil erosion of different intensities may occur, and the probability of soil erosion of different intensity levels is also different. Therefore, the risk of soil erosion can be expressed as

[0019] RISK=∑f i ·ω i

[0020] RISK is the soil erosion risk of a single pixel, f i is the probability of occurrence of soil erosion of different intensities, ω i is the intensity level of soil erosion;

[0021] B. Calculate the soil erosion risk of the study area according to step A in step 4.

[0022] Based on the above, in step 4, soil erosion risk is defined as the expected value of loss after soil erosion occurs. This loss includes two dimensions: soil erosion intensity and soil erosion probability. Therefore, the soil erosion risk can be expressed by the sum of the products of different soil erosion intensity levels and the corresponding soil erosion probability levels.

[0023] The present invention has outstanding substantial features and significant progress compared to the prior art. Specifically, the present invention has the following advantages:

[0024] The soil erosion risk assessment method provided by the present invention combines the soil erosion intensity level and the probability of soil erosion occurrence to obtain the expected value after soil erosion occurs. This makes up for the shortcomings of previous soil erosion risk assessment that directly uses soil erosion amount or soil erosion intensity instead of soil erosion risk without considering the probability of soil erosion occurrence. It provides a new reference for soil erosion monitoring and soil erosion control. In addition, the data used in the present invention can be obtained from public data sets on the Internet, which makes it easy to conduct soil erosion risk assessment on a certain regional scale. Therefore, it has certain promotion and application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is the overall technical framework diagram of the present invention

[0026] Figure 2 DEM data for the Dali River Basin

[0027] Figure 3 Precipitation data before and after resampling

[0028] Figure 4 Soil erosion modulus of the Dali River Basin in 2020

[0029] Figure 5 The probability of soil erosion of different intensities in the Dali River Basin from 2001 to 2020

[0030] Figure 6 Soil erosion risk in the Dali River Basin DETAILED DESCRIPTION

[0031] The technical solution of the present invention is further described in detail below through specific implementation methods.

[0032] Example

[0033] like Figure 1-6 As shown, this embodiment takes the Dali River Basin as the study area and provides a soil erosion risk assessment method based on the probability of soil erosion occurrence in combination with relevant data from 2001 to 2020.

[0034] The main technical ideas of the present invention are as follows Figure 1As shown in the following steps: First, obtain the multi-year soil erosion intensity data of the study area, which can be calculated using the universal soil loss equation; second, calculate the probability of occurrence of different soil erosion intensities in the study area based on the obtained multi-year soil erosion intensity data; third, define the soil erosion risk as the expected value of soil erosion, and calculate the soil erosion risk of the study area. The specific operation includes the following steps:

[0035] Step 1: Data preprocessing: the precipitation data, NDVI data, DEM data (such as Figure 2 ), land use data and soil data are registered in projection and coordinate system;

[0036] Specifically, if the data obtained have different resolutions, they should first be resampled to the same resolution using GIS software, and then all data should be projected into the same coordinate system. The precipitation data obtained in this study is GPM precipitation data with a spatial resolution of 0.1°. GIS software was used to resample it to the same resolution as the NDVI and DEM data, such as Figure 3 a, 3b.

[0037] Step 2: Prepare the multi-year soil erosion modulus distribution map of the study area based on the data obtained in step 1 (e.g. Figure 4 ), which comprises the following steps:

[0038] A. Obtain the rainfall erosivity factor R, slope length factor LS, soil erodibility factor K, vegetation cover factor C, and soil and water conservation measures factor P layers for the study area based on precipitation data, NDVI data, DEM data, land use data, and soil data;

[0039] B. Calculate the soil erosion modulus of the study area using the RUSLE equation based on the obtained factor layers.

[0040] A=R·K·L·S·C·P

[0041] Where A is the annual soil erosion modulus, unit is t / (km 2 y);

[0042] This method is used to calculate the multi-year soil erosion modulus of the study area, such as Figure 4 Shown is the soil erosion modulus in the study area in 2020.

[0043] Step 3: Based on the soil erosion modulus distribution map prepared in step 2, the soil erosion intensity of the study area over many years and the probability of occurrence of different soil erosion intensities (such as Figure 5 ), which comprises the following steps:

[0044] A. According to the soil erosion intensity classification standard in the soil erosion classification standard SL190-2007, the multi-year soil erosion intensity in the study area is divided into different levels ωi ;

[0045] B. Calculate the probability f of different soil erosion intensities in a single pixel based on the obtained soil erosion intensity results over many years. i ;

[0046] Step 4: Assess soil erosion risk in the study area, which includes the following steps:

[0047] A. Soil erosion risk is defined as the expected value after soil erosion occurs. For a single pixel, soil erosion of different intensities may occur, and the probability of soil erosion of different intensity levels is also different. Therefore, the risk of soil erosion can be expressed as

[0048] RISK∑f i ·ω i

[0049] RISK is the soil erosion risk of a single pixel, f i is the probability of occurrence of soil erosion of different intensities, ω i is the intensity level of soil erosion;

[0050] B. Calculate the soil erosion risk of the study area according to step A in step 4. The results are as follows Figure 6 shown.

[0051] It should be noted that the expected value mentioned in step 4A is the loss after soil erosion occurs. This loss includes two dimensions: soil erosion intensity and the probability of soil erosion occurring. Different levels of soil erosion may occur in a certain area, and the probabilities of soil erosion of different intensities are also different. Therefore, the soil erosion risk of this area can be expressed by the sum of the products of the soil erosion intensity and the probability of soil erosion of different intensities.

[0052] The soil erosion risk assessment method provided by the present invention combines the soil erosion intensity level and the probability of soil erosion occurrence to obtain the expected value after soil erosion occurs. This makes up for the shortcomings of previous soil erosion risk assessment that directly uses soil erosion amount or soil erosion intensity instead of soil erosion risk without considering the probability of soil erosion occurrence. It provides a new reference for soil erosion monitoring and soil erosion control. In addition, the data used in the present invention can be obtained from public data sets on the Internet, which makes it easy to conduct soil erosion risk assessment on a certain regional scale. Therefore, it has certain promotion and application value.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to preferred embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or some technical features can be replaced by equivalents without departing from the spirit of the technical solutions of the present invention. They should all be included in the scope of the technical solutions claimed for protection by the present invention.

Claims

1. A soil erosion risk assessment method based on soil erosion occurrence probability, characterized in that The following steps are involved: Step 1: Data preprocessing: align the precipitation data, NDVI data, DEM data, land use data, and soil data obtained in the study area in the projection and coordinate system; Step 2: Prepare a multi-year soil erosion modulus distribution map of the study area based on the data obtained in step 1, which includes the following steps: A. Obtain the rainfall erosivity factor R, slope length factor LS, soil erodibility factor K, vegetation cover factor C, and soil and water conservation measures factor P layers for the study area based on precipitation data, NDVI data, DEM data, land use data, and soil data; B. Calculate the soil erosion modulus of the study area using the RUSLE equation based on the obtained factor layers. A=R·K·L·S·C·P Where A is the annual soil erosion modulus, unit is t / (km 2 y); Step 3: Obtain the multi-year soil erosion intensity and the occurrence probability of different soil erosion intensities in the study area based on the soil erosion modulus distribution map prepared in step 2, which includes the following steps: A. According to the soil erosion intensity classification standard in the soil erosion classification standard SL190-2007, the multi-year soil erosion intensity in the study area is divided into different levels ω i ; B. Calculate the probability f of different soil erosion intensities in a single pixel based on the obtained soil erosion intensity results over many years. i ; Step 4: Assess soil erosion risk in the study area, which includes the following steps: A. Soil erosion risk is defined as the expected value after soil erosion occurs. For a single pixel, soil erosion of different intensities may occur, and the probability of soil erosion of different intensity levels is also different. Therefore, the risk of soil erosion can be expressed as RISK=∑f i ·ω i RISK is the soil erosion risk of a single pixel, f i is the probability of occurrence of soil erosion of different intensities, ω i is the intensity level of soil erosion; B. Calculate the soil erosion risk of the study area according to step A in step 4.

2. The soil erosion risk assessment method based on soil erosion occurrence probability according to claim 1 is characterized by: In step 4, soil erosion risk is defined as the expected value of loss after soil erosion occurs. This loss includes two dimensions: soil erosion intensity and soil erosion probability. Therefore, the soil erosion risk can be expressed by the sum of the products of different soil erosion intensity levels and the corresponding soil erosion probability levels.

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