Gully-type debris flow susceptibility judgment method based on DEM and application of gully-type debris flow susceptibility judgment method

Abstract

The invention discloses a gully-type debris flow susceptibility judgment method based on a DEM and application thereof, and belongs to the technical field of debris flow engineering.The method comprises the following steps that S1, filling preprocessing is conducted on DEM data with the resolution of 12.5 m, and concave land and flat areas are eliminated; s2, extracting a water flow direction by adopting a D8 algorithm; s3, calculating the confluence cumulant according to the water flow direction; s4, extracting the grids of which the confluence cumulant exceeds a threshold value as first-stage channels; s5, generating water outlet data containing channel arc section connection information; s6, calculating the longitudinal gradient of the channel; s7, extracting the upstream catchment area of the first-stage channel; s8, calculating gully type debris flow susceptibility judgment indexes; and S9, judging the susceptibility degree of gully-type debris flow. According to the method, the longitudinal gradient of the channel is combined with the upstream catchment area, the limitation of single factor evaluation is overcome, an efficient means is provided for regional debris flow risk screening, and the judgment accuracy is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of debris flow engineering technology, and in particular to a method for judging the susceptibility of gully-type debris flows based on DEM and its application. Background Technology

[0002] Gully-type debris flows are debris flows that occur in juvenile gullies or cut gullies on slopes. There are no tributaries in the watershed, the water system is not fully developed, the watershed is elongated, the gully erosion depth is shallow, and the longitudinal gradient is large.

[0003] There are currently no accurate methods, either domestically or internationally, for assessing the susceptibility of gully-type debris flows; only general qualitative assessments are available. Gully-type debris flows are highly concealed, requiring extensive field investigations and significant human and material resources to determine their susceptibility. Digital topographic images (DEMs) are digitized topographic data reflecting surface elevation information, containing rich topographic, geomorphological, and hydrological information, effectively reflecting the spatial distribution patterns and geomorphological features of the terrain. However, DEM-based research on debris flow susceptibility primarily focuses on gully-type debris flows, lacking rapid quantitative studies on the susceptibility of gully-type debris flows.

[0004] Current scientific research lacks accurate quantitative methods to determine the susceptibility of gully-type debris flows, particularly in assessing their susceptibility across different lithological regions. General debris flow susceptibility assessments rely on statistical methods. However, because the topographical features and formation mechanisms of gully-type debris flows differ from those of valley-type debris flows, susceptibility assessment values ​​for valley-type flows are not applicable to gully-type flows. Furthermore, it is not possible to rapidly determine the susceptibility of gully-type debris flows across different lithological regions based on DEM (Digital Image Processing).

[0005] The characteristics of residual soil formed from the weathering of different parent rocks vary, leading to different susceptibility to debris flows in gullies across different lithological regions. The permeability coefficient and clay mineral characteristics of the residual soil both influence landslide occurrence. Under otherwise identical conditions, a higher permeability coefficient in the residual soil makes landslides more likely, resulting in gully-type debris flows. Higher clay mineral content, especially montmorillonite, makes slopes more prone to fissures, leading to slope instability and thus gully-type debris flows. Rapid and cost-effective quantitative assessment of the susceptibility to gully-type debris flows is crucial and a primary disaster prevention measure.

[0006] Chinese patent application CN118865601A, published on October 29, 2024, discloses a method and system for detecting the hazard of landslide and debris flow disaster chains. The method includes: acquiring DEM data of a target detection area and dividing the target detection area into several watershed units; constructing a landslide and debris flow disaster chain index system, wherein the index system includes topographic indicators, source indicators, and hydrodynamic indicators; calculating the topographic and source indicators corresponding to the watershed units and assigning them hierarchical values; calculating the landslide and debris flow hazard susceptibility index of the watershed unit using a comprehensive index method based on the topographic and source indicators; calculating the hydrodynamic indicators corresponding to the watershed units and assigning them hierarchical values; and calculating the landslide and debris flow hazard hazard index of the watershed unit based on the susceptibility index and the hydrodynamic indicators.

[0007] The landslide and debris flow hazard chain hazard detection method and system disclosed in this patent application can improve the reliability of landslide and debris flow hazard detection results. However, the indicator system is quite complex, and coupling the assessment of landslide and debris flow hazard chains increases the difficulty and uncertainty of data acquisition, indicator quantification, and model construction in actual operation, thus affecting the detection accuracy. Summary of the Invention

[0008] To overcome the shortcomings of the prior art, this invention provides a method for judging the susceptibility of gully-type debris flows based on DEM and its application. This invention provides a systematic debris flow susceptibility judgment process based on quantitative topographic indicators, realizing automated analysis from digital elevation model to susceptibility level determination. By combining the longitudinal gradient of the gully with the upstream catchment area, it overcomes the limitations of single-factor assessment, provides an efficient means for regional debris flow risk screening, and greatly improves the accuracy of judgment.

[0009] This invention is achieved through the following technical solution: A method for determining the susceptibility of gully-type debris flows based on DEM includes the following steps: S1. Perform fill preprocessing on the DEM data with a resolution of 12.5m to eliminate depressions and flat areas; S2. Based on the preprocessed DEM data, the D8 algorithm is used to extract the water flow direction; S3. Calculate the cumulative flow based on the direction of water flow; S4. Set the current accumulation threshold and extract the grids whose current accumulation exceeds the threshold as primary channels; S5. Based on the primary channel, generate outlet data containing channel arc connection information; S6. Extract the starting and ending elevations of each primary channel and calculate the longitudinal gradient of the channel. S7. Taking the starting point of each primary channel as the outlet, extract the upstream catchment area of ​​the primary channel; S8, Through Calculate the susceptibility assessment index for gully-type debris flows; Wherein, G is the susceptibility index for gully-type debris flows, J is the longitudinal gradient of the gully, A is the upstream catchment area, and A0 is the unit area. S9. Based on the susceptibility indicators for gully-type debris flows and the lithology of the area where the gully is located, determine the degree of susceptibility for gully-type debris flows.

[0010] In step S1, the annotation preprocessing is completed using the spatial analysis module in the geographic information system software.

[0011] In step S2, the extraction of the water flow direction is completed through the hydrological analysis module in the geographic information system software.

[0012] In step S4, the cumulative flow threshold is 80. The grid calculator tool is used to assign a value of 1 to the grid with a cumulative flow greater than 80, and assign a value of no data to the rest, thereby extracting the first-level channel.

[0013] In step S5, the generation of the outlet data is completed through the hydrological analysis module in the geographic information system software.

[0014] In step S6, the longitudinal gradient of the channel is calculated by dividing the elevation difference between the starting and ending points of the channel by the channel length.

[0015] In step S7, the upstream catchment area is obtained by multiplying the cumulative flow by the unit grid area.

[0016] In step S9, when the gully is located in a granite area, the judgment criteria are: low susceptibility when G < 0.16, medium susceptibility when 0.16 ≤ G < 0.28, and high susceptibility when G ≥ 0.28.

[0017] In step S9, when the gully is located in a granulite area, the criteria are as follows: low susceptibility when G < 0.2, medium susceptibility when 0.2 ≤ G < 0.37, and high susceptibility when G ≥ 0.37.

[0018] In step S9, when the gully is located in a sandstone area, the judgment criteria are: low susceptibility when G < 0.2, medium susceptibility when 0.2 ≤ G < 0.4, and high susceptibility when G ≥ 0.4.

[0019] This invention is applicable to assessing the susceptibility of debris flows in gullies within the catchment areas surrounding mines.

[0020] The D8 algorithm described in this invention refers to a hydrological analysis algorithm that determines the direction of a single water flow in a 3×3 grid by using the steepest slope principle. That is, the direction of water flow exists only in 8 directions in the 3×3 grid, forming a water flow direction matrix.

[0021] The beneficial effects of this invention are mainly reflected in the following aspects: 1. This invention provides a systematic, topographically-based quantitative index-based debris flow susceptibility assessment process, which automates the analysis from digital elevation model to susceptibility level determination. By combining the longitudinal gradient of the channel with the upstream catchment area, it overcomes the limitations of single-factor assessment, provides an efficient means for regional debris flow risk screening, and greatly improves the accuracy of the assessment. 2. This invention, by performing depression-filling preprocessing, effectively eliminates local depressions in DEM data caused by errors or actual terrain, ensuring the continuity of water flow paths in subsequent hydrological analysis. 3. This invention uses the D8 algorithm to extract the direction of water flow. The calculation principle is clear and the efficiency is high. It can quickly generate the basic matrix describing the water flow path of each grid in the watershed, which is beneficial to improving the efficiency of subsequent susceptibility judgment. 4. This invention achieves objective and automated extraction of primary gully channels by setting a unified confluence accumulation threshold of 80, avoiding the subjectivity of manual delineation, and identifying grids exceeding the threshold as primary gullies. It can quickly identify debris flow sources and flow valleys with development potential from complex terrain.

[0022] 5. This invention can quantify the steepness of the ditch bed by extracting the elevations at both ends of the ditch and calculating the longitudinal gradient of the ditch.

[0023] 6. This invention clarifies the calculation method of upstream catchment area, which is obtained by converting the cumulative flow of water into the grid area, transforming the number of grids into an area value with actual physical meaning, which helps to improve the accuracy of subsequent judgments.

[0024] 7. This invention establishes differentiated susceptibility thresholds based on the geological and soil characteristics of granite areas, making the assessment results more consistent with the development patterns of debris flows in this lithological region. This zoning and classification criterion improves the pertinence and accuracy of risk assessment.

[0025] 8. This invention sets specific judgment thresholds for granulite areas, which are different from other lithologies. This reflects the influence of weathering products and soil characteristics of different lithologies on debris flow formation conditions. This refined standard enhances the applicability and reliability of the method in complex geological areas.

[0026] 9. This invention is applicable to assessing the susceptibility of debris flows in gullies within the catchment area surrounding a mine, thereby providing a basis for mine safety layout. Attached Figure Description

[0027] The present invention will now be further described in detail with reference to the accompanying drawings and specific embodiments: Figure 1 This is a flowchart of the susceptibility assessment of gully-type debris flows based on DEM according to the present invention. Detailed Implementation

[0028] Example 1 See Figure 1 A method for determining the susceptibility of gully-type debris flows based on DEM includes the following steps: S1. Perform fill preprocessing on the DEM data with a resolution of 12.5m to eliminate depressions and flat areas; S2. Based on the preprocessed DEM data, the D8 algorithm is used to extract the water flow direction; S3. Calculate the cumulative flow based on the direction of water flow; S4. Set the current accumulation threshold and extract the grids whose current accumulation exceeds the threshold as primary channels; S5. Based on the primary channel, generate outlet data containing channel arc connection information; S6. Extract the starting and ending elevations of each primary channel and calculate the longitudinal gradient of the channel. S7. Taking the starting point of each primary channel as the outlet, extract the upstream catchment area of ​​the primary channel; S8, Through Calculate the susceptibility assessment index for gully-type debris flows; Wherein, G is the susceptibility index for gully-type debris flows, J is the longitudinal gradient of the gully, A is the upstream catchment area, and A0 is the unit area. S9. Based on the susceptibility indicators for gully-type debris flows and the lithology of the area where the gully is located, determine the degree of susceptibility for gully-type debris flows.

[0029] This embodiment is the most basic implementation method, providing a systematic debris flow susceptibility assessment process based on topographic quantitative indicators. It realizes automated analysis from digital elevation model to susceptibility level determination. By combining the longitudinal gradient of the channel with the upstream catchment area, it overcomes the limitations of single-factor assessment, provides an efficient means for regional debris flow risk screening, and greatly improves the accuracy of judgment. Example 2 See Figure 1 A method for determining the susceptibility of gully-type debris flows based on DEM includes the following steps: S1. Perform fill preprocessing on the DEM data with a resolution of 12.5m to eliminate depressions and flat areas; S2. Based on the preprocessed DEM data, the D8 algorithm is used to extract the water flow direction; S3. Calculate the cumulative flow based on the direction of water flow; S4. Set the current accumulation threshold and extract the grids whose current accumulation exceeds the threshold as primary channels; S5. Based on the primary channel, generate outlet data containing channel arc connection information; S6. Extract the starting and ending elevations of each primary channel and calculate the longitudinal gradient of the channel. S7. Taking the starting point of each primary channel as the outlet, extract the upstream catchment area of ​​the primary channel; S8, Through Calculate the susceptibility assessment index for gully-type debris flows; Wherein, G is the susceptibility index for gully-type debris flows, J is the longitudinal gradient of the gully, A is the upstream catchment area, and A0 is the unit area. S9. Based on the susceptibility indicators for gully-type debris flows and the lithology of the area where the gully is located, determine the degree of susceptibility for gully-type debris flows.

[0030] Preferably, in step S1, the annotation preprocessing is completed using the spatial analysis module in the geographic information system software.

[0031] In step S2, the extraction of the water flow direction is completed through the hydrological analysis module in the geographic information system software.

[0032] This embodiment is a preferred implementation method. By performing depression filling preprocessing, local depressions caused by errors or actual terrain in the DEM data are effectively eliminated, ensuring the continuity of the flow path in subsequent hydrological analysis. The D8 algorithm is used to extract the water flow direction. The calculation principle is clear and the efficiency is high. It can quickly generate the basic matrix describing the water flow path of each grid in the watershed, which is beneficial to improving the efficiency of subsequent susceptibility judgment. Example 3 See Figure 1 A method for determining the susceptibility of gully-type debris flows based on DEM includes the following steps: S1. Perform fill preprocessing on the DEM data with a resolution of 12.5m to eliminate depressions and flat areas; S2. Based on the preprocessed DEM data, the D8 algorithm is used to extract the water flow direction; S3. Calculate the cumulative flow based on the direction of water flow; S4. Set the current accumulation threshold and extract the grids whose current accumulation exceeds the threshold as primary channels; S5. Based on the primary channel, generate outlet data containing channel arc connection information; S6. Extract the starting and ending elevations of each primary channel and calculate the longitudinal gradient of the channel. S7. Taking the starting point of each primary channel as the outlet, extract the upstream catchment area of ​​the primary channel; S8, Through Calculate the susceptibility assessment index for gully-type debris flows; Wherein, G is the susceptibility index for gully-type debris flows, J is the longitudinal gradient of the gully, A is the upstream catchment area, and A0 is the unit area. S9. Based on the susceptibility indicators for gully-type debris flows and the lithology of the area where the gully is located, determine the degree of susceptibility for gully-type debris flows.

[0033] In step S1, the annotation preprocessing is completed using the spatial analysis module in the geographic information system software.

[0034] In step S2, the extraction of the water flow direction is completed through the hydrological analysis module in the geographic information system software.

[0035] In step S4, the cumulative flow threshold is 80. The grid calculator tool is used to assign a value of 1 to the grid with a cumulative flow greater than 80, and assign a value of no data to the rest, thereby extracting the first-level channel.

[0036] This embodiment is another preferred implementation method. By setting a unified confluence accumulation threshold of 80, it achieves objective and automated extraction of primary gully channels, avoids the subjectivity of manual delineation, and identifies grids exceeding the threshold as primary gullies. It can quickly identify debris flow sources and flow valleys with development potential from complex terrain.

[0037] Example 4 See Figure 1 A method for determining the susceptibility of gully-type debris flows based on DEM includes the following steps: S1. Perform fill preprocessing on the DEM data with a resolution of 12.5m to eliminate depressions and flat areas; S2. Based on the preprocessed DEM data, the D8 algorithm is used to extract the water flow direction; S3. Calculate the cumulative flow based on the direction of water flow; S4. Set the current accumulation threshold and extract the grids whose current accumulation exceeds the threshold as primary channels; S5. Based on the primary channel, generate outlet data containing channel arc connection information; S6. Extract the starting and ending elevations of each primary channel and calculate the longitudinal gradient of the channel. S7. Taking the starting point of each primary channel as the outlet, extract the upstream catchment area of ​​the primary channel; S8, Through Calculate the susceptibility assessment index for gully-type debris flows; Wherein, G is the susceptibility index for gully-type debris flows, J is the longitudinal gradient of the gully, A is the upstream catchment area, and A0 is the unit area. S9. Based on the susceptibility indicators for gully-type debris flows and the lithology of the area where the gully is located, determine the degree of susceptibility for gully-type debris flows.

[0038] In step S1, the annotation preprocessing is completed using the spatial analysis module in the geographic information system software.

[0039] In step S2, the extraction of the water flow direction is completed through the hydrological analysis module in the geographic information system software.

[0040] More preferably, in step S4, the cumulative flow threshold is 80. The grid calculator tool is used to assign a value of 1 to the grid with a cumulative flow greater than 80, and assign a value of no data to the rest, thereby extracting the first-level channel.

[0041] In step S5, the generation of the outlet data is completed through the hydrological analysis module in the geographic information system software. In step S6, the longitudinal gradient of the channel is calculated by dividing the elevation difference between the channel's starting and ending points by the channel length. In step S7, the upstream catchment area is obtained by multiplying the cumulative runoff by the unit grid area.

[0042] This embodiment is another preferred implementation. By extracting the elevations at both ends of the channel and calculating the longitudinal gradient of the channel, the steepness of the channel bed can be quantified. The calculation method for the upstream catchment area is clarified, namely, it is obtained by converting the cumulative runoff volume into the grid area, transforming the number of grids into an area value with actual physical meaning, which helps to improve the accuracy of subsequent judgments.

[0043] Example 5 See Figure 1 A method for determining the susceptibility of gully-type debris flows based on DEM includes the following steps: S1. Perform fill preprocessing on the DEM data with a resolution of 12.5m to eliminate depressions and flat areas; S2. Based on the preprocessed DEM data, the D8 algorithm is used to extract the water flow direction; S3. Calculate the cumulative flow based on the direction of water flow; S4. Set the current accumulation threshold and extract the grids whose current accumulation exceeds the threshold as primary channels; S5. Based on the primary channel, generate outlet data containing channel arc connection information; S6. Extract the starting and ending elevations of each primary channel and calculate the longitudinal gradient of the channel. S7. Taking the starting point of each primary channel as the outlet, extract the upstream catchment area of ​​the primary channel; S8, Through Calculate the susceptibility assessment index for gully-type debris flows; Wherein, G is the susceptibility index for gully-type debris flows, J is the longitudinal gradient of the gully, A is the upstream catchment area, and A0 is the unit area. S9. Based on the susceptibility indicators for gully-type debris flows and the lithology of the area where the gully is located, determine the degree of susceptibility for gully-type debris flows.

[0044] In step S1, the annotation preprocessing is completed using the spatial analysis module in the geographic information system software.

[0045] In step S2, the extraction of the water flow direction is completed through the hydrological analysis module in the geographic information system software.

[0046] In step S4, the cumulative flow threshold is 80. The grid calculator tool is used to assign a value of 1 to the grid with a cumulative flow greater than 80, and assign a value of no data to the rest, thereby extracting the first-level channel.

[0047] In step S5, the generation of the outlet data is completed through the hydrological analysis module in the geographic information system software.

[0048] In step S6, the longitudinal gradient of the channel is calculated by dividing the elevation difference between the starting and ending points of the channel by the channel length.

[0049] In step S7, the upstream catchment area is obtained by multiplying the cumulative flow by the unit grid area.

[0050] In step S9, when the gully is located in a granite area, the judgment criteria are: low susceptibility when G < 0.16, medium susceptibility when 0.16 ≤ G < 0.28, and high susceptibility when G ≥ 0.28.

[0051] This embodiment is another preferred implementation method. Different susceptibility level thresholds were established based on the geological and soil characteristics of granite areas, so that the assessment results are more consistent with the development pattern of debris flows in this lithological area. This zoning and classification criterion improves the pertinence and accuracy of risk assessment.

[0052] Example 6 See Figure 1 A method for determining the susceptibility of gully-type debris flows based on DEM includes the following steps: S1. Perform fill preprocessing on the DEM data with a resolution of 12.5m to eliminate depressions and flat areas; S2. Based on the preprocessed DEM data, the D8 algorithm is used to extract the water flow direction; S3. Calculate the cumulative flow based on the direction of water flow; S4. Set the current accumulation threshold and extract the grids whose current accumulation exceeds the threshold as primary channels; S5. Based on the primary channel, generate outlet data containing channel arc connection information; S6. Extract the starting and ending elevations of each primary channel and calculate the longitudinal gradient of the channel. S7. Taking the starting point of each primary channel as the outlet, extract the upstream catchment area of ​​the primary channel; S8, Through Calculate the susceptibility assessment index for gully-type debris flows; Wherein, G is the susceptibility index for gully-type debris flows, J is the longitudinal gradient of the gully, A is the upstream catchment area, and A0 is the unit area. S9. Based on the susceptibility indicators for gully-type debris flows and the lithology of the area where the gully is located, determine the degree of susceptibility for gully-type debris flows.

[0053] In step S1, the annotation preprocessing is completed using the spatial analysis module in the geographic information system software.

[0054] In step S2, the extraction of the water flow direction is completed through the hydrological analysis module in the geographic information system software.

[0055] In step S4, the cumulative flow threshold is 80. The grid calculator tool is used to assign a value of 1 to the grid with a cumulative flow greater than 80, and assign a value of no data to the rest, thereby extracting the first-level channel.

[0056] In step S5, the generation of the outlet data is completed through the hydrological analysis module in the geographic information system software.

[0057] More preferably, in step S6, the longitudinal gradient of the channel is calculated by dividing the elevation difference between the starting and ending points of the channel by the channel length. In step S7, the upstream catchment area is obtained by multiplying the cumulative runoff by the unit grid area.

[0058] In step S9, when the gully is located in a granite area, the judgment criteria are: low susceptibility when G < 0.16, medium susceptibility when 0.16 ≤ G < 0.28, and high susceptibility when G ≥ 0.28.

[0059] In step S9, when the gully is located in a granulite area, the criteria are as follows: low susceptibility when G < 0.2, medium susceptibility when 0.2 ≤ G < 0.37, and high susceptibility when G ≥ 0.37.

[0060] This embodiment is another preferred implementation. For granulite areas, a specific judgment threshold that is different from other lithologies is set, which reflects the influence of weathering products and soil characteristics of different lithologies on debris flow formation conditions. This refined standard enhances the applicability and reliability of the method in complex geological areas.

[0061] Example 7 See Figure 1 A method for determining the susceptibility of gully-type debris flows based on DEM includes the following steps: S1. Perform fill preprocessing on the DEM data with a resolution of 12.5m to eliminate depressions and flat areas; S2. Based on the preprocessed DEM data, the D8 algorithm is used to extract the water flow direction; S3. Calculate the cumulative flow based on the direction of water flow; S4. Set the current accumulation threshold and extract the grids whose current accumulation exceeds the threshold as primary channels; S5. Based on the primary channel, generate outlet data containing channel arc connection information; S6. Extract the starting and ending elevations of each primary channel and calculate the longitudinal gradient of the channel. S7. Taking the starting point of each primary channel as the outlet, extract the upstream catchment area of ​​the primary channel; S8, Through Calculate the susceptibility assessment index for gully-type debris flows; Wherein, G is the susceptibility index for gully-type debris flows, J is the longitudinal gradient of the gully, A is the upstream catchment area, and A0 is the unit area. S9. Based on the susceptibility indicators for gully-type debris flows and the lithology of the area where the gully is located, determine the degree of susceptibility for gully-type debris flows.

[0062] In step S1, the annotation preprocessing is completed using the spatial analysis module in the geographic information system software.

[0063] In step S2, the extraction of the water flow direction is completed through the hydrological analysis module in the geographic information system software.

[0064] In step S4, the cumulative flow threshold is 80. The grid calculator tool is used to assign a value of 1 to the grid with a cumulative flow greater than 80, and assign a value of no data to the rest, thereby extracting the first-level channel.

[0065] In step S5, the generation of the outlet data is completed through the hydrological analysis module in the geographic information system software.

[0066] In step S6, the longitudinal gradient of the channel is calculated by dividing the elevation difference between the starting and ending points of the channel by the channel length.

[0067] In step S7, the upstream catchment area is obtained by multiplying the cumulative flow by the unit grid area.

[0068] In step S9, when the gully is located in a granite area, the judgment criteria are: low susceptibility when G < 0.16, medium susceptibility when 0.16 ≤ G < 0.28, and high susceptibility when G ≥ 0.28.

[0069] In step S9, when the gully is located in a granulite area, the criteria are as follows: low susceptibility when G < 0.2, medium susceptibility when 0.2 ≤ G < 0.37, and high susceptibility when G ≥ 0.37.

[0070] In step S9, when the gully is located in a sandstone area, the judgment criteria are: low susceptibility when G < 0.2, medium susceptibility when 0.2 ≤ G < 0.4, and high susceptibility when G ≥ 0.4.

[0071] This invention is applicable to assessing the susceptibility of debris flows in gullies within the catchment areas surrounding mines.

[0072] This embodiment is another preferred implementation method, which is suitable for assessing the susceptibility of debris flows in gullies within the catchment area around a mine, thereby providing a basis for mine safety layout. The invention will be further illustrated below with specific examples: According to the survey of 58 gullies that were affected by debris flows, these include: In 2009, a series of gully-type debris flows occurred in Niedu Township, Jiangxi Province; on June 18, 2010, a gully-type debris flow occurred in Shunchang County, Fujian Province; on June 18, 2010, a gully-type debris flow occurred in Yangkou Town, Fujian Province; on June 18, 2010, a gully-type debris flow occurred in Jiangle County, Fujian Province; on June 18, 2010, a gully-type debris flow occurred in Yanping County, Fujian Province; and on July 9, 2019, a gully-type debris flow occurred in Pucheng County, Fujian Province.

[0073] Table 1 shows the parameters of 58 gully-type debris flows and the calculated gully-type debris flow susceptibility index G.

[0074] Table 1

[0075]

[0076]

[0077] Table 1 shows that 17 granite areas were identified as having a high susceptibility to debris flows based on DEM analysis, and all of them experienced debris flows. Table 1 shows 13 of the granite areas identified by rapid DEM analysis for gully debris flow susceptibility, all of which resulted in debris flows.

[0078] Table 1 shows that two areas in the granulite rock region are highly susceptible to debris flows based on rapid DEM analysis, and debris flows have occurred in both of them. Table 1 shows 22 locations in the gully debris flow susceptibility assessment based on DEM in granulite areas, all of which experienced debris flows.

[0079] In Table 1, two of the sandstone areas were identified as prone to debris flows based on DEM rapid assessment of gully debris flow, and both of them experienced debris flows. Table 1 shows two areas in sandstone regions with low susceptibility to debris flows, which were quickly determined based on DEM, and both of them experienced debris flows.

[0080] In summary, the method described in this invention has high accuracy in determining the susceptibility of gully-type debris flows in granite, granulite, and sandstone areas.

Claims

1. A method for determining the susceptibility of gully-type debris flows based on DEM, characterized in that, Includes the following steps: S1. Perform fill preprocessing on the DEM data with a resolution of 12.5m to eliminate depressions and flat areas; S2. Based on the preprocessed DEM data, the D8 algorithm is used to extract the water flow direction; S3. Calculate the cumulative flow based on the direction of water flow; S4. Set the current accumulation threshold and extract the grids whose current accumulation exceeds the threshold as primary channels; S5. Based on the primary channel, generate outlet data containing channel arc connection information; S6. Extract the starting and ending elevations of each primary channel and calculate the longitudinal gradient of the channel. S7. Taking the starting point of each primary channel as the outlet, extract the upstream catchment area of ​​the primary channel; S8, Through Calculate the susceptibility assessment index for gully-type debris flows; Wherein, G is the susceptibility index for gully-type debris flows, J is the longitudinal gradient of the gully, A is the upstream catchment area, and A0 is the unit area. S9. Based on the susceptibility indicators for gully-type debris flows and the lithology of the area where the gully is located, determine the degree of susceptibility for gully-type debris flows.

2. The method for determining the susceptibility of gully-type debris flows based on DEM according to claim 1, characterized in that: In step S1, the annotation preprocessing is completed using the spatial analysis module in the geographic information system software.

3. The method for determining the susceptibility of gully-type debris flows based on DEM according to claim 1, characterized in that: In step S2, the extraction of the water flow direction is completed through the hydrological analysis module in the geographic information system software.

4. The method for determining the susceptibility of gully-type debris flows based on DEM according to claim 1, characterized in that: In step S4, the cumulative flow threshold is 80. The grid calculator tool is used to assign a value of 1 to the grid with a cumulative flow greater than 80, and assign a value of no data to the rest, thereby extracting the first-level channel.

5. The method for determining the susceptibility of gully-type debris flows based on DEM according to claim 1, characterized in that: In step S6, the longitudinal gradient of the channel is calculated by dividing the elevation difference between the starting and ending points of the channel by the channel length.

6. The method for determining the susceptibility of gully-type debris flows based on DEM according to claim 1, characterized in that: In step S7, the upstream catchment area is obtained by multiplying the cumulative flow by the unit grid area.

7. The method for determining the susceptibility of gully-type debris flows based on DEM according to claim 1, characterized in that: In step S9, when the gully is located in a granite area, the judgment criteria are: low susceptibility when G < 0.16, medium susceptibility when 0.16 ≤ G < 0.28, and high susceptibility when G ≥ 0.

28.

8. The method for determining the susceptibility of gully-type debris flows based on DEM according to claim 1, characterized in that: In step S9, when the gully is located in a granulite area, the criteria are as follows: low susceptibility when G < 0.2, medium susceptibility when 0.2 ≤ G < 0.37, and high susceptibility when G ≥ 0.

37.

9. The method for determining the susceptibility of gully-type debris flows based on DEM according to claim 1, characterized in that: In step S9, when the gully is located in a sandstone area, the judgment criteria are: low susceptibility when G < 0.2, medium susceptibility when 0.2 ≤ G < 0.4, and high susceptibility when G ≥ 0.

4.

10. An application of a DEM-based method for determining the susceptibility of gully-type debris flows, characterized in that: The DEM-based method for assessing the susceptibility of gully-type debris flows as described in any one of claims 1-9 is applicable to evaluating the susceptibility of debris flows in gullies within the catchment area surrounding a mine.

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