An evaluation method for the interference impact of soil erosion on power transmission and transformation lines

Abstract

The present invention relates to the technical field of transmission and transformation line design, and discloses an evaluation method for the influence of soil erosion interference on transmission and transformation lines, including: obtaining Sentinel-2 data of the area to be monitored, and calculating the soil erosion modulus and extracting the coordinates of the tower bases to be detected according to the Sentinel-2 data; performing dynamic analysis of soil erosion in the "area-linear-point" range of the transmission and transformation line based on the obtained soil erosion modulus and the coordinates of the tower bases to be detected; calculating the potential influence of soil erosion interference in the "area-linear-point" range of the transmission and transformation line based on the obtained dynamic analysis results of soil erosion, and judging the spatial range and intensity of soil erosion interference occurring in the transmission and transformation line; within the influence range of soil erosion interference on the transmission and transformation line, grading and evaluating the intensity of the influence of soil erosion interference on the transmission and transformation line, so as to propose specific ecological protection spatial and temporal boundaries during the construction and operation period of the transmission and transformation line; the present invention has the advantages of high result credibility and ensuring the minimization of the influence of soil erosion interference.

Description

Technical Field

[0001] The present invention relates to a method for evaluating the interference impact of soil erosion on transmission and transformation lines, belonging to the technical field of transmission and transformation line design. Background Art

[0002] At present, the research on soil erosion of transmission lines focuses on erosion characteristics, erosion restoration, erosion monitoring, etc. The soil erosion characteristics of transmission and transformation projects are closely related to geographical and geomorphic conditions. It is found that there are significant differences in the influencing factors and prevention key points of soil erosion in transmission line projects in different mountainous areas across the country; the construction links that cause soil erosion are different on the steep slopes of the plain-hilly-mountainous areas in North China; the soil erosion volume of the construction roads in the loess area of Shanxi accounts for 40% - 70% of the total loss volume; the soil erosion modulus of transmission and transformation projects in mountainous areas is 1.2 - 1.9 times that of the plain area; in recent years, the erosion area of typical transmission and transformation projects in Hubei has decreased compared with the water and soil conservation plan. In terms of erosion restoration, the study using MODIS data on the Hubei section of the Jiuquan - Hunan ±800KV UHV DC transmission line in the past 6 years found that soil erosion has been effectively controlled. In terms of erosion monitoring, three monitoring methods, namely investigation and monitoring, standard plot sampling analysis method, and patrol monitoring, are used to monitor the implementation status of soil and water conservation during the construction period; currently, most monitoring is based on the water and soil conservation plan, and the monitoring results are obtained through ground observation method, analogy method, and investigation method; the theory and method for geological disaster early warning during the construction of UHV AC transmission and transformation based on China's Beidou satellite navigation system and high-resolution remote sensing technology can also be applied to soil erosion monitoring; the regular inspection system for transmission and transformation lines based on low-altitude remote sensing by unmanned aerial vehicle can also add soil erosion monitoring content; using a variety of high-resolution image data, remote monitoring of the implementation of soil and water conservation during the construction period of the Liuyang 500KV transmission and transformation project line; the technical solution of "satellite remote sensing census + unmanned aerial vehicle detailed investigation + manual on-site spot check" is also applied to the soil erosion monitoring of the 500kV transmission and transformation project in Wangcheng, Changsha, Hunan. To sum up, the current research on soil erosion of transmission line projects is based on the characteristic analysis of the water and soil conservation plan. The water and soil conservation plan assumes that the soil erosion intensity during the entire construction period is a fixed value, and the soil erosion range during the construction period is within the project scope. In fact, due to seasonal differences in precipitation and vegetation during the construction period, the soil erosion intensity will show seasonal changes, and the soil erosion influence range in mountainous areas is larger than the project footprint. Currently, the research on the "remote sensing - ground investigation" monitoring technology focuses on the monitoring of water and soil conservation measures in the construction area, and there is less research on whether the soil erosion around the construction area is affected.

[0003] Based on this, we provide a method for evaluating the interference impact of soil erosion on transmission and transformation lines to provide a more accurate basis for the implementation period and implementation area of soil and water conservation measures for transmission and transformation projects. Summary of the Invention

[0004] An evaluation method for the interference impact of soil erosion on transmission and transformation lines.

[0005] The technical solution of the present invention is as follows:

[0006] An evaluation method for the interference impact of soil erosion on transmission and transformation lines, characterized by comprising the following steps:

[0007] Obtain Sentinel-2 data of the area to be monitored, and calculate the soil erosion modulus and extract the coordinates of the tower bases to be detected according to the Sentinel-2 data;

[0008] Conduct dynamic analysis of soil erosion in the "area - line - point" range of the transmission and transformation line according to the obtained soil erosion modulus and the coordinates of the tower bases to be detected;

[0009] Calculate the potential impact of soil erosion interference in the "area - line - point" range of the transmission and transformation line based on the obtained dynamic analysis results of soil erosion, and judge the spatial range and intensity of the occurrence of soil erosion interference on the transmission and transformation line;

[0010] Within the scope of the interference impact of soil erosion on the transmission and transformation line, conduct a hierarchical evaluation of the interference impact intensity of soil erosion on the transmission and transformation line to propose specific ecological protection spatial and temporal boundaries during the construction and operation period of the transmission and transformation line.

[0011] Furthermore, the method for obtaining Sentinel-2 data of the area to be detected is as follows:

[0012] A1) Screen and download Sentinel-2 remote sensing image data with less cloud cover and good quality from the European Space Agency website, and download the Sen2Cor plugin to the user folder from the European Space Agency website. Load the plugin in cmd to perform radiometric calibration and atmospheric correction operations on the remote sensing image;

[0013] A2) Download and install the SNAP software on the European Space Agency website. Open the SNAP software, load the data after radiometric calibration and atmospheric correction, open the resampling tool, resample all bands of the remote sensing image to 10 meters, and set the output format to ENVI;

[0014] A3) The storage method of the data obtained in A2 is one file for each band. Use the layerstacking tool of ENVI software to fuse bands 2, 3, 4, and 8, and set the projection parameters to UTM WGS 1984 Zone 51N to obtain a multi-band file. Mosaic and crop four remote sensing images in the same quarter to obtain the preprocessed remote sensing image data of the area to be monitored, that is, the Sentinel-2 data of the area to be detected.

[0015] Further, the calculation of the soil erosion modulus includes the following steps: Calculate according to the calculation formula of the RUSLE model, and the calculation formula is as follows:

[0016] A = R × K × LS × C × P

[0017] Among them, A is the annual average soil erosion modulus per unit area, and the unit is (t / hm2•a);

[0018] R is the rainfall erosivity factor, and the unit is (MJ•mm) / (hm2•h•a). The R factor is calculated using the rainfall erosivity estimation method proposed by the first author Zhou Fujian for Fujian Province;

[0019] K is the soil erodibility factor. The K factor is calculated using the EPIC model proposed by the first author Williams, and the unit is (t•hm2•h) / (hm2•MJ•mm);

[0020] LS is the slope length and slope factor, and the LS factor is estimated according to the formula proposed by the first author Liu Baoyuan;

[0021] C represents the vegetation cover and management factor. The C factor is calculated according to the vegetation coverage formula, and the formula is as follows: .

[0022] Among them, is the vegetation coverage, is the NDVI value contributed by vegetation, is the NDVI value contributed by bare land;

[0023] Then, after modifying the model established by the first author Cai Chongfa, the relationship between C and the vegetation coverage is established, which is specifically as follows:

[0024]

[0025] P is the soil and water conservation measure factor, and the P factor is assigned values for different land use types. Using maximum likelihood classification and taking the photos taken by equipment such as unmanned aerial vehicles during on-site reconnaissance as auxiliary data for land use type classification, the land use types in the study area are divided into 5 categories to obtain the land use type map. Specifically, the land use types in the monitoring area are divided into 5 categories: water area and water conservancy facilities land, forest land, garden land, construction land, and bare land; generally, no protection measures are taken for bare land, and its P value is 1, the P value of water area and water conservancy facilities land and construction land is 0, the P value of forest land is 0.2, and the P value of garden land is 0.4;

[0026] LS, C, and P are all dimensionless.

[0027] Furthermore, the extraction of the coordinates of the tower bases to be detected can be directly obtained based on the Sentinel-2 data of the area to be detected.

[0028] The method for dynamically analyzing soil erosion in the "area - linear - point" range of transmission and transformation lines includes the following steps: Referring to the method for determining the evaluation range in HJ19 - 2022 Technical Guidelines for Environmental Impact Assessment - Ecological Impact, using the neighborhood analysis tool in ArcGIS, set a line buffer with a range of 200 meters on both sides of the transmission and transformation line. This line buffer is the linear study area of the transmission and transformation line. Using the neighborhood analysis tool in ArcGIS, set a point buffer with a radius of 30 meters centered on the coordinates of the tower bases to be detected. This point buffer is the point study area. At the same time, also set a buffer with a radius of 30 meters centered on the substation location for the substation and include it in the point study area, that is, constitute the "area - linear - point" range of the transmission and transformation line. Then, according to the actual construction data of the project, such as the construction period of the project, the precipitation distribution characteristics of the area where the project is located, Sentinel data, etc., divide it into three seasons: spring, summer, autumn and winter, and the years before construction, during construction and during the recovery period. After that, considering the years before construction, during construction and during the recovery period, conduct a dynamic analysis of soil erosion in the "area - linear - point" range of the transmission and transformation line by the method of superposition and comparison analysis according to the soil erosion modulus combined with the data of each season and each year. The soil erosion dynamics specifically include the seasonal dynamics of soil erosion, the dynamic of soil erosion intensity before and after construction, and the dynamic of the area proportion of soil erosion grades before and after construction.

[0029] Furthermore, the method for calculating the potential impact of soil erosion interference in the "area - linear - point" range of transmission and transformation lines includes the following steps: Propose a formula for calculating the potential impact of soil erosion interference, specifically:

[0030] Use the formula to calculate the change in soil erosion intensity, where A t2 is the soil erosion intensity between years t2, and A t1 is the soil erosion intensity between years t1;

[0031] Use the formula to calculate the change in soil erosion intensity under natural background conditions, where A t2自然 is the soil erosion intensity under natural background conditions between years t2, and A t1自然 is the soil erosion intensity under natural background conditions between years t1;

[0032] Use the formula to calculate the soil erosion intensity under interference conditions, where A t自然 is the soil erosion intensity under natural background conditions between years t, and A t纯干扰 is the soil erosion intensity under interference conditions between years t;

[0033] Utilize a formula to calculate the change amount of soil erosion intensity under disturbed conditions, where A t2纯干扰 is the soil erosion intensity under disturbed conditions between year t2, and A t1自然 is the soil erosion intensity under natural background conditions between year t1, and A t2自然 is the soil erosion intensity under natural background conditions between year t2;

[0034] Utilize the formula to calculate the potential impact value of soil erosion interference between year t2, where is the change amount of soil erosion intensity under disturbed conditions between year t2 and year t1, is the change amount of soil erosion intensity under natural background conditions between year t2 and year t1.

[0035] Furthermore, the method for judging the spatial range and intensity of soil erosion interference of transmission and transformation lines includes the following steps: Combine the soil erosion modulus, the "regional - linear - point - like" range of the transmission and transformation lines, and the soil erosion intensity under the disturbed conditions, and compare the potential impact values of soil erosion interference in the "regional - linear - point - like" range of the transmission and transformation lines before construction and during construction, so as to judge the spatial range and intensity of soil erosion interference of the transmission and transformation lines.

[0036] Furthermore, the method for grading and evaluating the impact intensity of soil erosion interference of transmission and transformation lines includes the following steps:

[0037] B1) Use ArC software to load the potential impact layer of linear interference of the transmission and transformation lines according to the "regional - linear - point - like" range of the transmission and transformation lines, and assign colors with obvious grade differences to the layer, so as to extract the tower base groups and time periods with strong influence, and thus divide the key protection areas;

[0038] B2) Extract each tower base point of the tower base group with strong influence into an EXCEL table, and summarize the soil erosion intensity of each quarter corresponding to the tower base group with strong influence, and draw a change diagram;

[0039] B3) According to the drawn change diagram, propose specific ecological protection spatial and temporal boundaries during the construction and operation period of the transmission and transformation lines, so as to minimize the impact of soil erosion interference of the transmission and transformation project.

[0040] The present invention has the following beneficial effects:

[0041] 1. The present invention obtains Sentinel-2 data of the area to be monitored. Based on the remote sensing image data of Sentinel-2, which has the advantage of high resolution, it can ensure the accuracy of the data obtained in the area to be detected. At the same time, only by installing the Sen2Cor plug-in, the radiometric calibration and atmospheric correction operations of the remote sensing image can be quickly completed, which has the advantages of simplicity, practicality, speed and convenience.

[0042] 2. The present invention calculates the soil erosion modulus by using the internationally common RUSLE model framework. The model makes a regional empirical correction to the C factor parameter, and corrects the vegetation coverage threshold range in the relationship model (piecewise function) between the C factor and the vegetation coverage, so that the calculation result of the soil erosion modulus is more consistent with the relevant analog results, thereby further improving the credibility of the results.

[0043] 3. Based on the seasonal characteristics of soil erosion and the dynamic characteristics before and after the construction of the transmission and transformation line, the present invention proposes a calculation formula for the potential impact of soil erosion interference, obtains a calculation method for the interference impact of soil erosion during the construction of the transmission and transformation line project of the transmission and transformation line, and then identifies and judges the impact space range of the transmission and transformation project based on the potential impact of soil erosion interference, so as to obtain the spatial boundary and intensity of the occurrence of soil erosion interference of the transmission and transformation line. Then, by grading and evaluating the intensity of the soil erosion interference impact of the transmission and transformation line, the specific ecological protection space and time boundary during the construction and operation period of the transmission and transformation line can be proposed to ensure the minimization of the soil erosion interference impact of the transmission and transformation project.

[0044] 4. The present invention uses the "area-linear-point" design, applies the estimation result of the regional soil erosion intensity based on the remote sensing image to the actual transmission and transformation project, and obtains the grading evaluation map of the soil erosion interference impact of the transmission and transformation line based on the spatial impact range and seasonal dynamics of soil erosion. Among them, the key prevention and control areas and periods are clarified, providing a specific practical basis for the construction supervision of the transmission and transformation line and soil erosion, so as to ensure the minimization of the soil erosion interference impact of the transmission and transformation project. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 is the technical flow chart of the embodiment of the present invention;

[0046] Figure 2 is the land use type (drone photo) of the research area in the embodiment of the present invention;

[0047] Figure 3 (a-f) are the soil erosion intensity change maps from 2018 to 2020 in the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0048] The present invention will be described in detail below with reference to the drawings and specific embodiments.

[0049] Example: Please refer to Figures 1 to 3 In this example, a method for evaluating the interference impact of soil erosion on power transmission and transformation lines includes the following steps: Obtain Sentinel-2 data of the area to be monitored, and calculate the soil erosion modulus and extract the coordinates of the tower bases to be detected based on the Sentinel-2 data; conduct dynamic analysis of soil erosion in the "area - line - point" range of the power transmission and transformation lines according to the obtained soil erosion modulus and the coordinates of the tower bases to be detected; calculate the potential impact of soil erosion interference in the "area - line - point" range of the power transmission and transformation lines based on the obtained dynamic analysis results of soil erosion, and judge the spatial range and intensity of soil erosion interference on the power transmission and transformation lines; within the scope of the impact of soil erosion interference on the power transmission and transformation lines, conduct a hierarchical evaluation of the intensity of the impact of soil erosion interference on the power transmission and transformation lines to propose specific ecological protection spatial and temporal boundaries during the construction and operation periods of the power transmission and transformation lines.

[0050] Furthermore, in this example, a certain county through which a power transmission line in a subtropical coastal mountainous area (a project in Fujian) passes is taken as a specific example to elaborate on the method of this example in detail.

[0051] 1 Estimate the regional soil erosion intensity using multi-temporal Sentinel-2 data with a 10-meter resolution;

[0052] The multi-source data used in this example are Sentinel-2 data provided by the ESA website (https: / / earth.esa.int / web / guest / home) with a spatial resolution of 10 meters; rainfall data provided by the NASA website (https: / / www.nasa.gov / ) with a spatial resolution of 10 kilometers; soil property data provided by the Nanjing Institute of Soil Science (http: / / www.issas.ac.cn / ), digital elevation data of ASTER GDEM provided by the Geospatial Data Cloud (http: / / www.gscloud.cn / ) with a spatial resolution of 30 meters; and administrative division data provided by the Resource and Environment Science and Data Center of the Chinese Academy of Sciences (https: / / www.resdc.cn / Default.aspx).

[0053] 1.1 Soil erosion intensity accounting method

[0054] In this example, the Revised Universal Soil Loss Equation (RUSLE) is adopted. This model summarizes the physical and management factors affecting the soil erosion rate into 5 main factors: rainfall erosivity factor, soil erodibility factor, slope length and slope factor, vegetation cover and management factor, and soil and water conservation engineering measure factor. The calculation formula of the RUSLE model is as follows:

[0055] A = R × K × LS × C × P

[0056] Among them, A is the annual average soil erosion modulus per unit area, with the unit of (t / hm2•a); R is the rainfall erosivity factor, with the unit of (MJ•mm) / (hm2•h•a); K is the soil erodibility factor, with the unit of (t•hm2•h) / (hm2•MJ•mm); LS is the slope length and slope factor; C represents the vegetation cover and management factor; P is the soil and water conservation measure factor; LS, C, and P are all dimensionless.

[0057] 1.1.1 Rainfall Erosivity Factor R

[0058] In this embodiment, the rainfall erosivity factor R adopts the rainfall erosivity estimation method proposed by the first author Zhou Fujian in Fujian Province.

[0059] 1.1.2 Soil Erodibility Factor K

[0060] The soil erodibility factor K reflects the inherent characteristics of the soil and represents the resistance to the scouring and splash erosion effects of rainfall. In this embodiment, the Williams' EPIC model is used to estimate the K value. The soil property data all come from the Nanjing Institute of Soil Science (http: / / www.issas.ac.cn / ).

[0061] 1.1.3 Topographic Factor LS

[0062] The topographic factor includes the slope length factor and the slope factor. In this embodiment, the research method of the first author Liu Baoyuan is adopted to estimate the LS factor.

[0063] 1.1.4 Vegetation Cover and Management Factor C

[0064] The vegetation coverage is the percentage of the vertical projection area of the vegetation on the ground to the total area and is a factor that inhibits the erosion power.

[0065] In this embodiment, according to , the vegetation coverage is calculated , is the NDVI value contributed by the vegetation, is the NDVI value contributed by the bare land; after modifying the model established by the first author Cai Chongfa, the relationship between C and the vegetation coverage is established as follows:

[0066]

[0067] 1.1.5 Soil and Water Conservation Measure Factor P

[0068] In this embodiment, the maximum likelihood classification method in supervised classification is adopted to classify the land use types in the monitoring area into 7 categories: water body, cultivated land, low vegetation, high vegetation, bare land, building, and road. In this embodiment, the photos taken by the drone during the on-site survey are used as auxiliary data for land use type classification. The naming of land use classification follows the "Classification of Current Land Use" (GB / T 21010-2017), and supervised classification is performed on Sentinel-2 data to obtain the land use classification maps of the study area at different times. By comparative analysis, the P factor values suitable for different land use types in the study area are determined (see Table 1).

[0069] Table 1 P factor values corresponding to different land use types

[0070]

[0071] 2 Seasonal dynamics of soil erosion in the "area - linear - point" spatial range of transmission lines

[0072] According to the climate characteristics of the monitoring area where the autumn and winter boundaries are not obvious and it is generally dry, less rainy, and warm, the year is divided into three quarters: spring, summer, and autumn and winter to study the seasonal changes in soil erosion intensity. In this embodiment, the soil erosion modulus calculated by the RUSLE model is similar to the regional research results published currently and the observation results of the soil and water conservation test site of the Fujian Soil and Water Conservation Supervision Station. The study area belongs to the southern red soil hilly area, and the classification of soil erosion intensity refers to the "Classification and Grading Standard for Soil Erosion" (SL 190-2007) formulated by the Ministry of Water Resources of China in 2007. As shown in Table 3, the grading results are shown in Figure 2 This study period is from 2018 to 2020. According to the construction progress of a transmission line project in Fujian, it is divided into three periods: before construction (preparation period), construction period, and recovery period (Table 2). This paper studies the soil erosion intensity and grade distribution characteristics of the transmission line according to the "area (3276.55 km²) - linear area (200 m buffer zone on both sides of the line, area 15.28 km²) - point area (30 m buffer zone centered on the tower base, area 0.47 km²)" spatial range, and the results are shown in Figure 3 and Table 4.

[0073] Table 2 Study periods

[0074]

[0075] Table 3 Grading standard for soil erosion intensity

[0076]

[0077] 2.1 Seasonal changes in regional soil erosion intensity

[0078] Such as Figure 2, During the research period, the soil conservation status in the region was good. The region was mainly dominated by slight and mild erosion, and the area with moderate or above erosion was very small, showing a punctate distribution. Overall, the erosion intensity in the northwest of the region was higher than that in the east.

[0079] Figure 3 (a) shows that the seasonal variation law of soil erosion in the study area from 2018 to 2019 was summer > spring > autumn and winter, and in 2020 it was spring > summer > autumn and winter. The spring had the largest variation range, the soil erosion was stronger in summer, and the erosion was weak in autumn and winter with the smallest annual variation range. The regional average values of soil erosion intensity in spring, summer, and autumn from 2018 to 2020 were: 0.83 - 4.21 t / hm2•a, 1.42 - 3.05 t / hm2•a, 0.79 - 0.94 t / hm2•a respectively. The soil erosion intensity in spring 2020 was much higher than that in spring in the previous two years and summer in the same year, which was closely related to the uneven seasonal and annual distribution of precipitation.

[0080] The research shows that the area proportions of slight, mild, and moderate or above soil erosion in spring from 2018 to 2020 were: 82.91 - 94.41%, 5.37 - 11.77%, 0.23 - 5.31% respectively; the area proportions of slight, mild, and moderate or above soil erosion in summer were: 85.84 - 92.03%, 6.95 - 10.68%, 1.01 - 3.48% respectively; the area proportions of slight, mild, extremely strong, and severe soil erosion in autumn and winter were: 94.61 - 96.47%, 3.52 - 5.23%, 0.01 - 0.21% respectively.

[0081] 2.2 Dynamic soil erosion in the linear range of transmission lines

[0082] Figure 3 (b) shows that the seasonal variation law of soil erosion intensity in the linear area was similar to the regional variation law. The soil erosion intensity in summer was higher than that in spring from 2018 to 2019, while the soil erosion intensity in spring was higher than that in summer in 2020, and the soil erosion intensity was the lowest in autumn and winter. The average values of soil erosion intensity in spring, summer, and autumn in the linear area from 2018 to 2020 were: 0.43 - 3.75 t / hm2•a, 1.02 - 1.51 t / hm2•a, 0.42 - 0.75 t / hm2•a respectively. The average soil erosion intensity in the linear area in spring 2020 was 3.75 t / hm2•a, significantly higher than 0.43 and 0.85 t / hm2•a in the linear area in spring in 2018 and 2019, while the erosion intensities in summer and autumn and winter were basically the same in the three years.

[0083] The study shows that in the spring of 2018-2020, the proportions of areas with slight, mild, and moderate soil erosion in the linear zone were 84.14-97.76%, 2.16-10.91%, and 0.08-4.94%, respectively; in summer, the proportions of areas with slight, mild, and moderate soil erosion were 92.04-93.55%, 5.35-7.02%, and 0.49-1.78%, respectively; in autumn and winter, the proportions of areas with slight, mild, and moderate soil erosion were 95.74-98.28%, 1.70-4.21%, and 0-0.05%, respectively. Comparing the proportions of soil erosion grade areas in the three quarters within three years, in the spring of 2020, the area with slight erosion accounted for 84.14%, and the area with slight erosion accounted for 10.91%. Compared with 2018 and 2019, the area with slight soil erosion in the linear zone in the spring of 2020 decreased significantly, while the area with slight erosion increased.

[0084] 2.3 Soil erosion dynamics at the transmission line point

[0085] Figure 3 (c) shows that the average soil erosion intensity in the dotted area from 2018 to 2019 is smaller than that in the linear area and the regional area, but the soil erosion intensity in 2020 (construction period) is significantly greater than that in the same season of 2018-2019. The seasonal variation pattern is similar to that of the linear area and the regional area. The average soil erosion intensity in the dotted area in spring, summer and autumn from 2018 to 2020 is 0.35-4.00 t / hm2•a, 0.90-3.67 t / hm2•a, and 0.22-1.33 t / hm2•a, respectively. The average soil erosion intensity in the dotted area in spring, summer, autumn and winter of 2020 is 4.00, 3.67 and 1.33 t / hm2•a, respectively, which is 8.73, 3.93 and 1.49 times the erosion intensity in the same season of 2019, respectively.

[0086] Research shows that the area proportions of slight, mild, and moderate or above soil erosion in the punctate area in spring from 2018 to 2020 are 84.19 - 98.33%, 1.67 - 10.11%, and 0.00 - 5.71% respectively; in summer, they are 81.03 - 95.32%, 3.63 - 15.17%, and 0.30 - 3.80% respectively; in autumn and winter, they are 92.00 - 99.44%, 0.56 - 8.00%, and 0.00% respectively. Comparing the area proportions of soil erosion grades in the three seasons within three years, the proportions of slight, mild, and moderate or above erosion areas in spring 2020 are 84.19%, 10.11%, and 5.71% respectively, and in summer 2020, they are 81.03%, 15.17%, and 3.80% respectively. Compared with 2018 and 2019, the proportion of slight erosion area in the punctate area in spring and summer 2020 has decreased significantly, while the proportions of mild and moderate or above erosion areas have increased significantly. The proportions of areas with each erosion grade in autumn and winter 2020 are close to those in the previous two years.

[0087] 3 Identification and Judgment of the Spatial Range of Soil Erosion Interference of Transmission and Transformation Lines

[0088] The construction of transmission lines is a process of interfering with the background soil. Based on the dynamic characteristics of soil erosion, this embodiment proposes a calculation formula for the potential impact of soil erosion interference. Soil erosion is a dynamic process that changes over time. The difference in soil erosion intensity between adjacent years can reflect the magnitude of this variation. Assuming that the soil erosion fluctuation between adjacent years in the region is the background change value, the change in soil erosion caused by interference conditions is equal to the superposition of the background change and the potential impact of interference. The potential impact of the interference on soil erosion intensity is calculated using Formula 5 - 9. Formula 5 is the change in soil erosion intensity between two years; Formula 6 is the change in soil erosion intensity in the region under natural background conditions; Formula 7 is the soil erosion intensity under interference conditions; Formula 8 is the change in soil erosion intensity under the condition of being interfered; Formula 9 is the potential impact of soil erosion interference. Formulas 5 - 9 are as follows:

[0089] Formula 5 , where A t2 is the soil erosion intensity between years t2, and A t1 is the soil erosion intensity between years t1;

[0090] Formula 6 , where A t2自然 is the soil erosion intensity under natural background conditions between years t2, and A t1自然 is the soil erosion intensity under natural background conditions between years t1;

[0091] Formula 7 , where A t自然 is the soil erosion intensity under natural background conditions during the t years, and A t纯干扰 is the soil erosion intensity under disturbed conditions during the t years;

[0092] Formula 8 , where A t2纯干扰 is the soil erosion intensity under disturbed conditions during the t2 years, and A t1自然 is the soil erosion intensity under natural background conditions during the t1 years, and A t2自然 is the soil erosion intensity under natural background conditions during the t2 years;

[0093] Formula 9 , where is the change amount of soil erosion intensity under disturbed conditions between the t2 years and the t1 years, is the change amount of soil erosion intensity under natural background conditions between the t2 years and the t1 years.

[0094] According to Formulas 5 - 9, the change amount of soil erosion in the same season between years in the region is calculated. Combining with the construction section of the transmission line (Table 2), the potential impact of soil erosion that may be caused by the construction of the transmission line is obtained.

[0095] Figure 3 It can be seen from (d) and Table 4 that the average change amount of soil erosion intensity in spring during the construction period is 1.69 t / hm2•a higher than that in the same period before construction, an increase of 199.4%. However, the change amount of erosion intensity in summer during the construction period is less than that in the background period by 2.41 t / hm2•a. Since the construction period of the transmission line is one year, in the subtropical coastal mountainous area, the vegetation recovery period takes about one year, and the change amount of soil erosion in summer during the construction period is less than that in the background period. Therefore, from the regional research scale, there may be doubts about the potential impact of soil erosion of the transmission and transformation line. It is very likely that there are other interferences in the region in addition to the transmission project interference, or there are natural ecological processes or ecological engineering measures in the region that are conducive to weakening the interference impact of soil erosion. At the same time, the occupied area of the transmission and transformation line project is 25.02 hm2, accounting for 0.008% of the regional area. Therefore, the result of the potential impact of soil erosion of the transmission line obtained from the regional spatial scale is not credible.

[0096] According to Figure 3(e) and Table 4, the change in soil erosion intensity in spring during the construction period in the linear area (2.89 t / hm²•a) is 5.81 times greater than the change in soil erosion modulus in spring before construction (0.42 t / hm²•a). However, the change in soil erosion intensity in summer during the construction period (-0.20 t / hm²•a) is smaller than the change during the background period (0.49 t / hm²•a), and it is reasonable that the erosion intensity during the natural recovery period is smaller than that during the construction period. Therefore, the potential impact of soil erosion in spring in the linear area of the transmission line is relatively large, and the soil erosion intensity in autumn and winter during the recovery period is effectively alleviated. However, the potential impact of soil erosion in summer is -0.69 t / hm²•a. Therefore, a question is raised whether the potential impact of soil erosion obtained in the linear area is affected by other interferences. The project floor area is 3.05% of the linear area. In addition to the impact of the transmission line project in the linear area, more areas are affected by other human interferences or have no interference. Therefore, it can be inferred that the credibility of the potential impact of soil erosion of the transmission line obtained at the linear area scale is low.

[0097] According to Figure 3 (f) and Table 4, the change in soil erosion intensity in spring during the construction period in the point area (3.53 t / hm²•a) is 3.43 t / hm²•a greater than the change in soil erosion modulus in spring before construction (0.10 t / hm²•a). The change in soil erosion intensity in summer during the construction period (2.74 t / hm²•a) is 2.72 t / hm²•a greater than the change during the background period (0.02 t / hm²•a). The change in erosion intensity in autumn and winter during the natural recovery period (0.44 t / hm²•a) is 0.24 t / hm²•a less than the change in erosion intensity in autumn and winter during the construction period (0.68 t / hm²•a). The potential impact of soil erosion of the transmission line obtained according to Formula 12 is positive in both spring and summer in the point area. The floor area of the transmission line is 53.69% of the area of the point area. Therefore, at the point spatial scale, the potential impact of soil erosion of the transmission line is credible.

[0098] Table 4 Average change in soil erosion intensity in the study area (t / hm²∙a)

[0099]

[0100] The potential impacts of soil erosion on transmission lines in different spatial ranges were calculated according to Equation 5-9 (Table 4). The patterns in the regional and linear models were relatively consistent. The potential impacts of soil erosion on transmission line projects in spring were both positive, being 1.69 and 2.47 t / hm2•a respectively, while those in summer were negative, indicating that soil erosion during the summer construction period was less than that before construction. In the coastal mountainous areas with hot and rainy climate conditions, assuming that the soil erosion intensity in the study area (regional, linear, and point-like) is only affected by the construction of transmission lines, then in summer and spring, with large amounts of rainfall, the potential impacts of soil erosion generated must be positive. If it is negative, the assumption does not hold, that is, the change in soil erosion intensity caused by the assumed disturbance is less than the change in background soil erosion intensity, meaning that the disturbance impact is very small. For the 30m point buffer zone, the disturbance impacts of soil erosion on transmission lines during the spring and summer construction periods were higher than those before construction, and the potential impact intensities of soil erosion in spring and summer were 3.43 and 2.71 t / hm2•a respectively. This impact is the real disturbance caused by the transmission lines on soil erosion.

[0101] Evaluation of the Disturbance Impact of Soil Erosion on Transmission and Transformation Lines

[0102] The evaluation of the disturbance impact of soil erosion on transmission lines is discussed from two aspects: spatial range and time period. According to the quantitative calculation of the average value of the potential impact of soil erosion, the disturbance impact of soil erosion on transmission lines is characterized by a point-like dispersion pattern. Therefore, the evaluation range of the disturbance impact of soil erosion during the construction period of transmission lines should be the 30m buffer zone based on the tower base points to calculate the quantitative value of the disturbance impact of soil erosion. At the same time, according to the seasonal dynamics of soil erosion on transmission lines and the dynamic characteristics of soil erosion before and after construction in Section 2, spring and summer are important time periods for the disturbance impact of soil erosion during the construction period, and soil erosion prevention measures must be well implemented during these two time periods.

[0103] Specific to the transmission line of a project in Fujian, the soil erosion interference impact values of each tower base point can be quantitatively calculated. Select the tower base points with large interference impacts as the key prevention and control areas, and other tower base points as general prevention and control areas to achieve hierarchical prevention and control of soil erosion on the transmission line. The key areas include 21 tower base points and substations, including JA2, ZA20, ZA26, ZA37, ZAG39, ZA41, JA14, JA18, ZB8, ZB27, ZB28, ZB33, ZB35, JB12, ZB36, ZB37, ZBG41, ZB49, JB17, JB18, and the substation, with a total area of 13.64 hm2. The potential soil erosion impact amounts during the construction period in spring and summer are respectively: 2.31 - 47.51, 2.09 - 13.55 t / hm2•a, and the average values are respectively 11.78 and 6.41 t / hm2•a, which are 3.43 and 2.36 times the average potential soil erosion impact of the point source area (Table 4). The potential soil erosion impacts in spring at the tower base points ZA37 and ZB33 in the key prevention and control sub-districts are respectively 47.51 and 44.77 t / hm2•a, and the potential soil erosion impacts in summer at ZB35 and ZBG41 are respectively 13.22 and 13.55 t / hm2•a, which should be particularly concerned about.

[0104] The above are only the embodiments of the present invention, and do not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, shall be similarly included in the patent protection scope of the present invention.

Claims

1. An evaluation method for the impact of soil erosion interference on power transmission and transformation lines, characterized in that, it includes the following steps: Obtain Sentinel-2 data of the area to be monitored, and calculate the soil erosion modulus according to the Sentinel-2 data and extract the coordinate points of the tower bases to be detected; Conduct dynamic analysis of soil erosion in the "area - linear - point" range of the power transmission and transformation line based on the obtained soil erosion modulus and the coordinate points of the tower bases to be detected; Calculate the potential impact of soil erosion interference in the "area - linear - point" range of the power transmission and transformation line based on the obtained results of the dynamic analysis of soil erosion, and judge the spatial range and intensity of the occurrence of soil erosion interference on the power transmission and transformation line; Within the scope of the impact of soil erosion interference on the power transmission and transformation line, conduct a hierarchical evaluation of the intensity of the impact of soil erosion interference on the power transmission and transformation line to propose specific ecological protection spatial and temporal boundaries during the construction and operation periods of the power transmission and transformation line; Among them, the method for conducting dynamic analysis of soil erosion in the "area - linear - point" range of the power transmission and transformation line includes the following steps: Take the range of 200 meters on both sides of the power transmission and transformation line as the linear study area, take the coordinate points of the tower bases to be detected as the center, and the range with a radius of 30 meters as the point study area. At the same time, set a buffer zone with a radius of 30 meters centered on the substation location for the substation and incorporate it into the point study area, that is, form the "area - linear - point" range of the power transmission and transformation line. Then, according to the actual construction data of the project, divide it into three seasons of spring, summer, autumn and winter, and the years before construction, during construction and after recovery. Finally, conduct dynamic analysis of soil erosion in the "area - linear - point" range of the power transmission and transformation line according to the soil erosion modulus combined with the data of each season and each year; The method for calculating the potential impact of soil erosion interference in the "area - linear - point" range of the power transmission and transformation line includes the following steps: Propose a calculation formula for the potential impact of soil erosion interference, specifically: Using the formula to calculate the change in soil erosion intensity, where A t2 is the soil erosion intensity during year t2, and A t1 is the soil erosion intensity during year t1; Using the formula calculate the change in soil erosion intensity under natural background conditions, where A t2自然 is the soil erosion intensity under natural background conditions between the years of t2, and A t1自然 is the soil erosion intensity under natural background conditions between the years of t1; Using the formula to calculate the soil erosion intensity under interference conditions, where A t自然 is the soil erosion intensity under natural background conditions during the t-year period, and A t纯干扰 is the soil erosion intensity under interference conditions during the t-year period; Using the formula to calculate the change in soil erosion intensity under disturbed conditions, where A t2纯干扰 is the soil erosion intensity under disturbed conditions between years t2, and A t1自然 is the soil erosion intensity under natural background conditions between years t1, and A t2自然 is the soil erosion intensity under natural background conditions between years t2; Using the formula calculate the potential impact value of soil erosion disturbance between t2 years, where is the change in soil erosion intensity under disturbed conditions between t2 and t1 years, is the change in soil erosion intensity under natural background conditions between t2 and t1 years.

2. The evaluation method for the impact of soil erosion interference on a power transmission and transformation line according to claim 1, characterized in that, the calculation of the soil erosion modulus includes the following steps: Calculate according to the calculation formula of the RUSLE model, and the calculation formula is as follows: A = R×K×LS×C×P Where, A is the annual average soil erosion modulus per unit area, with the unit of (t / hm2•a), R is the rainfall erosivity factor, with the unit of (MJ•mm) / (hm2•h•a), K is the soil erodibility factor, with the unit of (t•hm2•h) / (hm2•MJ•mm), LS is the slope length and slope factor, C represents the vegetation cover and management factor, and P is the soil and water conservation measure factor; LS, C and P are all dimensionless.

3. The evaluation method for the impact of soil erosion interference on a power transmission and transformation line according to claim 1, characterized in that, the soil erosion dynamics specifically refer to the seasonal dynamics of soil erosion, the dynamic changes of soil erosion intensity before and after construction, and the dynamic changes of the area ratio of soil erosion grades before and after construction.

4. The evaluation method for the impact of soil erosion interference on a power transmission and transformation line according to claim 1, characterized in that, The method for judging the spatial range and intensity of soil erosion interference in transmission and transformation lines includes the following steps: Judging the spatial range and intensity of soil erosion interference in transmission and transformation lines by combining the soil erosion modulus, the "area - line - point" range of the transmission and transformation lines, and the potential influence value of soil erosion interference.

5. A method for evaluating the impact of soil erosion interference in transmission and transformation lines according to claim 4, characterized in that the method for grading and evaluating the intensity of soil erosion interference in transmission and transformation lines includes the following steps: Extracting the tower base groups and time periods strongly affected according to the "area - line - point" range of the transmission and transformation lines, dividing the key protection areas, summarizing the soil erosion intensity of the tower base groups strongly affected, drawing a change diagram, and proposing specific ecological protection spatial and temporal boundaries during the construction and operation periods of the transmission and transformation lines according to the change diagram.

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