Gully type debris flow accumulation range prediction method and application thereof

Abstract

The invention discloses a gully type debris flow accumulation range prediction method and application thereof, and belongs to the technical field of debris flow prevention and control engineering, and the method comprises the following steps: 1, determining the height difference between the highest point of a gully and a gully opening; 2, according to the height difference between the highest point of the channel and the trench opening, calculating the height difference between the central point of the potential instability object source and the trench opening; 3, determining the position of the most leading edge where the debris flow is finally accumulated, and then measuring the distance from the ditch opening to the position of the most leading edge; 4, determining the gradient of the accumulation area through field investigation, and calculating an accumulation fan divergence angle according to the gradient of the accumulation area; and 5, predicting the range of the debris flow accumulation fan according to the distance from the gully opening to the foremost edge position and the diffusion angle of the accumulation fan. According to the method, the gully-type debris flow accumulation starting-movement-accumulation characteristics are considered, so that the gully-type debris flow accumulation range is influenced, a prediction model for more accurately judging the gully-type debris flow accumulation range is provided, the prediction precision is high, and the applicability is good.

Description

Technical Field

[0001] This invention relates to the field of debris flow prevention and control engineering technology, and in particular to a method for predicting the deposition range of gully-type debris flows and its application. Background Technology

[0002] Gully-type debris flows are a type of debris flow disaster that is distributed in juvenile erosion gullies or cut gullies on slopes. They are characterized by their strong concealment and great destructive power. Their formation process includes four stages: rainwater infiltration, slope instability, landslide liquefaction and disintegration, and gully erosion.

[0003] Currently, research on predicting the depositional extent of debris flows mainly focuses on gully-type and slope-type debris flows, with relatively mature prediction models and assessment indicators. However, due to significant differences in topographic features and formation mechanisms, existing models are difficult to directly apply to predicting the depositional extent of gully-type debris flows. There is currently a lack of quantitative prediction methods for gully-type debris flows, which restricts the effectiveness of risk assessment and prevention of this type of debris flow disaster. Therefore, establishing a rapid and effective depositional extent prediction model suitable for gully-type debris flows is of great significance for reducing disaster losses.

[0004] Chinese patent application CN110532684A, published on December 3, 2019, discloses a method for predicting the outflow volume after the collapse of a debris flow dam. The method comprises the following steps: A: Construct a geometric stacking model of the dam body during the collapse of a debris flow barrier dam; B: Extract the geometric morphological parameters of the dam body geometric accumulation model constructed in step A when the debris flow dam overflows and fails, and apply the extracted geometric morphological parameters to the calculation model of the outflow amplification factor after the debris flow dam fails. C: Based on the failure mode of the landslide dam overtopping and the triangle principle, a quantitative analysis is conducted by combining the water storage of the landslide lake when it is full and the solid material reserve of the dam breach. A calculation model for the outflow amplification factor is constructed, and the geometric morphological parameters of the debris flow overtopping and failure extracted in step B are substituted into the calculation model for the outflow amplification factor to calculate and analyze the outflow amplification factor. D: Based on the outflow amplification factor calculated in step C, predict the outflow volume after the debris flow dam collapses.

[0005] The patent application discloses a method for predicting the outflow volume after a debris flow dam collapse. This method calculates the outflow volume after the collapse using geometric parameters, enabling rapid debris flow prevention. However, it is unsuitable for determining the deposition range of debris flows in gullies, and its prediction accuracy and applicability are poor. Summary of the Invention

[0006] To overcome the shortcomings of the prior art, this invention provides a method for predicting the deposition range of gully-type debris flows and its application. This invention takes into account the characteristics of gully-type debris flow deposition—initiation, movement, and deposition—which affect the deposition range of gully-type debris flows, and provides a more accurate prediction model for judging the deposition range of gully-type debris flows. The prediction model has high accuracy and good applicability.

[0007] This invention is achieved through the following technical solution: A method for predicting the deposition range of gully-type debris flows includes the following steps: Step 1: Obtain contour data of the debris flow basin, draw longitudinal profile of the basin based on the contour data, determine the highest point of the basin channel and the location of the channel mouth where the debris flow begins to expand on the longitudinal profile, and determine the elevation difference between the highest point of the channel and the channel mouth. Step 2: Calculate the elevation difference between the center point of the potential instability source and the mouth of the channel based on the elevation difference between the highest point of the channel and the channel mouth; Step 3: Calculate the horizontal projection distance from the center point of the unstable debris source to the leading edge of the final debris flow deposition, determine the position of the leading edge of the final debris flow deposition, and then measure the distance from the mouth of the gully to the leading edge position. Step 4: Determine the slope of the depositional area through field surveys, and calculate the diffusion angle of the depositional fan based on the slope of the depositional area; Step 5: Based on the distance from the mouth of the gully to the foremost edge and the diffusion angle of the debris flow fan, predict the extent of the debris flow depositional fan.

[0008] In step two, the height difference between the center point of the potential unstable material source and the mouth of the trench is calculated using Equation 1; Formula 1 Where: Hp—the elevation difference between the center point of the potential unstable material source and the mouth of the channel, m; H—the elevation difference between the highest point of the channel and the mouth of the channel, m.

[0009] In step three, the horizontal projection distance from the center point of the unstable material source to the leading edge of the final debris flow accumulation is calculated using Equation 2. Formula 2 Where: L——the horizontal projection distance from the center point of the unstable material source to the leading edge of the final debris flow deposition, m; Hp——the elevation difference between the center point of the potential unstable material source and the mouth of the gully, m.

[0010] In step four, the diffusion angle of the stacked fan is calculated using Equation 3; Formula 3 In the formula: R—diffusion angle of the stacking fan, degrees; —Slope of the accumulation zone, degrees.

[0011] In step four, determining the slope of the depositional area through field investigation refers to selecting three representative profiles on the surface of the depositional fan in the field for actual measurement and taking the average value.

[0012] In step five, when predicting the extent of the debris flow depositional fan, a fan-shaped area is drawn as the predicted depositional extent, with the gully mouth as the vertex, the distance from the gully mouth to the foremost edge as the radius, and the diffusion angle of the depositional fan as the opening angle.

[0013] An application of a method for predicting the deposition range of gully-type debris flows includes the following steps: S1. Predict and determine the extent of debris flow depositional fans as early warning zones; S2. Install rain gauges, mud level or ground acoustic monitoring sensors in the upstream gully of the warning area, and set warning thresholds related to the activation of potential unstable material sources. S3. When the monitoring data exceeds the warning threshold, a debris flow warning message is automatically generated and released.

[0014] The basic principle of this invention is as follows: The formation mechanism of gully debris flows is that, under rainfall conditions, landslides in the watershed become unstable and enter the gully, or the deposit source in the gully is activated and flows out of the gully mouth along the straight gully and accumulates.

[0015] The reasons for the small accumulation area of ​​debris flows include: 1. The relative elevation difference of the landslide source is too small: If the relative elevation of the starting point of the loose material source is too small, the potential energy of the source is too small. After the loose material on the gully bed becomes unstable, it is difficult to form a debris flow in the gully and it will only accumulate in the gully. Second, under the same conditions, as the slope of the deposition area increases, the maximum width of the deposition area decreases. This is because as the slope increases, the debris flow velocity is greater, which weakens the deposition effect on both sides. Third, the relative elevation difference of the material source initiation point and the slope of the deposition area do not play a role independently: when the potential energy of the material source initiation point is large, the slope of the deposition area is large, and the deposition range is long and flat along the direction of the gully mouth; similarly, when the potential energy of the material source initiation point is small, the slope of the deposition area is small, and the deposition range is short and wide along the direction of the gully mouth. Fourth, the slope of the depositional zone mainly affects the lateral diffusion range of debris flows, and the farthest distance a debris flow travels is mainly related to the potential energy of the potential unstable material source.

[0016] The beneficial effects of this invention are mainly reflected in the following aspects: 1. Compared with the prior art, the present invention takes into account the characteristics of gully debris flow deposition—initiation, movement, and deposition—which affect the deposition range of gully debris flows, and provides a more accurate predictive model for judging the deposition range of gully debris flows. The model has high prediction accuracy and good applicability. 2. This invention proposes a quantitative method for predicting the deposition range of gully-type debris flows by studying the outflow distance and deposition zone characteristics of such flows, resulting in higher prediction accuracy. 3. This invention proposes a quantitative calculation method by studying the influence of the predictive index of the relative elevation difference of potential unstable material sources on the depositional distance of debris flows, including a quantitative watershed relative elevation difference, which further improves the prediction accuracy.

[0017] 4. This invention, by studying the farthest distance of debris flow deposition and the farthest movement position of debris flow, makes the predicted debris flow deposition range more accurate and has stronger applicability.

[0018] 5. This invention establishes a method for calculating the diffusion angle of debris flow in a depositional fan and the lateral deposition range of debris flow by studying the relationship between the diffusion angle of debris flow in the depositional area and the slope of the depositional area. The predicted deposition range of debris flow is more reliable.

[0019] 6. This invention, by studying the depositional characteristics of gully debris flows in relation to the slope of the depositional zone, constructs a depositional range of gully debris flows related to relative elevation difference and depositional fan slope, making the prediction results more reliable and applicable. Attached Figure Description

[0020] 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 present invention. Detailed Implementation

[0021] Example 1 See Figure 1 A method for predicting the deposition range of gully-type debris flows includes the following steps: Step 1: Obtain contour data of the debris flow basin, draw longitudinal profile of the basin based on the contour data, determine the highest point of the basin channel and the location of the channel mouth where the debris flow begins to expand on the longitudinal profile, and determine the elevation difference between the highest point of the channel and the channel mouth. Step 2: Calculate the elevation difference between the center point of the potential instability source and the mouth of the channel based on the elevation difference between the highest point of the channel and the channel mouth; Step 3: Calculate the horizontal projection distance from the center point of the unstable debris source to the leading edge of the final debris flow deposition, determine the position of the leading edge of the final debris flow deposition, and then measure the distance from the mouth of the gully to the leading edge position. Step 4: Determine the slope of the depositional area through field surveys, and calculate the diffusion angle of the depositional fan based on the slope of the depositional area; Step 5: Based on the distance from the mouth of the gully to the foremost edge and the diffusion angle of the debris flow fan, predict the extent of the debris flow depositional fan.

[0022] This embodiment is the most basic implementation method. Compared with the prior art, considering the characteristics of gully debris flow deposition—initiation, movement, and deposition—which affect the deposition range of gully debris flows, a more accurate prediction model for judging the deposition range of gully debris flows is given. The prediction accuracy is high and the applicability is good. Example 2 See Figure 1 A method for predicting the deposition range of gully-type debris flows includes the following steps: Step 1: Obtain contour data of the debris flow basin, draw longitudinal profile of the basin based on the contour data, determine the highest point of the basin channel and the location of the channel mouth where the debris flow begins to expand on the longitudinal profile, and determine the elevation difference between the highest point of the channel and the channel mouth. Step 2: Calculate the elevation difference between the center point of the potential instability source and the mouth of the channel based on the elevation difference between the highest point of the channel and the channel mouth; Step 3: Calculate the horizontal projection distance from the center point of the unstable debris source to the leading edge of the final debris flow deposition, determine the position of the leading edge of the final debris flow deposition, and then measure the distance from the mouth of the gully to the leading edge position. Step 4: Determine the slope of the depositional area through field surveys, and calculate the diffusion angle of the depositional fan based on the slope of the depositional area; Step 5: Based on the distance from the mouth of the gully to the foremost edge and the diffusion angle of the debris flow fan, predict the extent of the debris flow depositional fan.

[0023] In step two, the height difference between the center point of the potential unstable material source and the mouth of the trench is calculated using Equation 1; Formula 1 Where: Hp—the elevation difference between the center point of the potential unstable material source and the mouth of the channel, m; H—the elevation difference between the highest point of the channel and the mouth of the channel, m.

[0024] This embodiment is a preferred implementation method. By studying the outflow distance and deposition zone characteristics of gully-type debris flows, a quantitative prediction method for the deposition range of gully-type debris flows is proposed, which has higher prediction accuracy. Example 3 See Figure 1 A method for predicting the deposition range of gully-type debris flows includes the following steps: Step 1: Obtain contour data of the debris flow basin, draw longitudinal profile of the basin based on the contour data, determine the highest point of the basin channel and the location of the channel mouth where the debris flow begins to expand on the longitudinal profile, and determine the elevation difference between the highest point of the channel and the channel mouth. Step 2: Calculate the elevation difference between the center point of the potential instability source and the mouth of the channel based on the elevation difference between the highest point of the channel and the channel mouth; Step 3: Calculate the horizontal projection distance from the center point of the unstable debris source to the leading edge of the final debris flow deposition, determine the position of the leading edge of the final debris flow deposition, and then measure the distance from the mouth of the gully to the leading edge position. Step 4: Determine the slope of the depositional area through field surveys, and calculate the diffusion angle of the depositional fan based on the slope of the depositional area; Step 5: Based on the distance from the mouth of the gully to the foremost edge and the diffusion angle of the debris flow fan, predict the extent of the debris flow depositional fan.

[0025] In step two, the height difference between the center point of the potential unstable material source and the mouth of the trench is calculated using Equation 1; Formula 1 Where: Hp—the elevation difference between the center point of the potential unstable material source and the mouth of the channel, m; H—the elevation difference between the highest point of the channel and the mouth of the channel, m.

[0026] In step three, the horizontal projection distance from the center point of the unstable material source to the leading edge of the final debris flow accumulation is calculated using Equation 2. Formula 2 Where: L——the horizontal projection distance from the center point of the unstable material source to the leading edge of the final debris flow deposition, m; Hp——the elevation difference between the center point of the potential unstable material source and the mouth of the gully, m.

[0027] This embodiment is another preferred implementation. By studying the influence of the prediction index of the relative elevation difference of potential unstable material sources on the debris flow deposition and movement distance, a quantitative calculation method is proposed, including a quantitative watershed relative elevation difference, which further improves the prediction accuracy.

[0028] Example 4 See Figure 1 A method for predicting the deposition range of gully-type debris flows includes the following steps: Step 1: Obtain contour data of the debris flow basin, draw longitudinal profile of the basin based on the contour data, determine the highest point of the basin channel and the location of the channel mouth where the debris flow begins to expand on the longitudinal profile, and determine the elevation difference between the highest point of the channel and the channel mouth. Step 2: Calculate the elevation difference between the center point of the potential instability source and the mouth of the channel based on the elevation difference between the highest point of the channel and the channel mouth; Step 3: Calculate the horizontal projection distance from the center point of the unstable debris source to the leading edge of the final debris flow deposition, determine the position of the leading edge of the final debris flow deposition, and then measure the distance from the mouth of the gully to the leading edge position. Step 4: Determine the slope of the depositional area through field surveys, and calculate the diffusion angle of the depositional fan based on the slope of the depositional area; Step 5: Based on the distance from the mouth of the gully to the foremost edge and the diffusion angle of the debris flow fan, predict the extent of the debris flow depositional fan.

[0029] In step two, the height difference between the center point of the potential unstable material source and the mouth of the trench is calculated using Equation 1; Formula 1 Where: Hp—the elevation difference between the center point of the potential unstable material source and the mouth of the channel, m; H—the elevation difference between the highest point of the channel and the mouth of the channel, m.

[0030] In step three, the horizontal projection distance from the center point of the unstable material source to the leading edge of the final debris flow accumulation is calculated using Equation 2. Formula 2 Where: L——the horizontal projection distance from the center point of the unstable material source to the leading edge of the final debris flow deposition, m; Hp——the elevation difference between the center point of the potential unstable material source and the mouth of the gully, m.

[0031] In step four, the diffusion angle of the stacked fan is calculated using Equation 3; Formula 3 In the formula: R—diffusion angle of the stacking fan, degrees; —Slope of the accumulation zone, degrees.

[0032] This embodiment is another preferred implementation method. By studying the farthest distance of debris flow deposition and the farthest movement position of debris flow, the predicted debris flow deposition range is more accurate and has stronger applicability.

[0033] Example 5 See Figure 1 A method for predicting the deposition range of gully-type debris flows includes the following steps: Step 1: Obtain contour data of the debris flow basin, draw longitudinal profile of the basin based on the contour data, determine the highest point of the basin channel and the location of the channel mouth where the debris flow begins to expand on the longitudinal profile, and determine the elevation difference between the highest point of the channel and the channel mouth. Step 2: Calculate the elevation difference between the center point of the potential instability source and the mouth of the channel based on the elevation difference between the highest point of the channel and the channel mouth; Step 3: Calculate the horizontal projection distance from the center point of the unstable debris source to the leading edge of the final debris flow deposition, determine the position of the leading edge of the final debris flow deposition, and then measure the distance from the mouth of the gully to the leading edge position. Step 4: Determine the slope of the depositional area through field surveys, and calculate the diffusion angle of the depositional fan based on the slope of the depositional area; Step 5: Based on the distance from the mouth of the gully to the foremost edge and the diffusion angle of the debris flow fan, predict the extent of the debris flow depositional fan.

[0034] In step two, the height difference between the center point of the potential unstable material source and the mouth of the trench is calculated using Equation 1; Formula 1 Where: Hp—the elevation difference between the center point of the potential unstable material source and the mouth of the channel, m; H—the elevation difference between the highest point of the channel and the mouth of the channel, m.

[0035] In step three, the horizontal projection distance from the center point of the unstable material source to the leading edge of the final debris flow accumulation is calculated using Equation 2. Formula 2 Where: L——the horizontal projection distance from the center point of the unstable material source to the leading edge of the final debris flow deposition, m; Hp——the elevation difference between the center point of the potential unstable material source and the mouth of the gully, m.

[0036] In step four, the diffusion angle of the stacked fan is calculated using Equation 3; Formula 3 In the formula: R—diffusion angle of the stacking fan, degrees; —Slope of the accumulation zone, degrees.

[0037] In step four, determining the slope of the depositional area through field investigation refers to selecting three representative profiles on the surface of the depositional fan in the field for actual measurement and taking the average value.

[0038] In step five, when predicting the extent of the debris flow depositional fan, a fan-shaped area is drawn as the predicted depositional extent, with the gully mouth as the vertex, the distance from the gully mouth to the foremost edge as the radius, and the diffusion angle of the depositional fan as the opening angle.

[0039] This embodiment is another preferred implementation method. By studying the relationship between the diffusion angle of debris flow in the depositional area and the slope of the depositional area, a method for calculating the diffusion angle of gully debris flow in the depositional fan and the lateral depositional range of debris flow was established, and the predicted debris flow depositional range is more reliable.

[0040] Example 6 See Figure 1 An application of a method for predicting the deposition range of gully-type debris flows includes the following steps: S1. Predict and determine the extent of debris flow depositional fans as early warning zones; S2. Install rain gauges, mud level or ground acoustic monitoring sensors in the upstream gully of the warning area, and set warning thresholds related to the activation of potential unstable material sources. S3. When the monitoring data exceeds the warning threshold, a debris flow warning message is automatically generated and released.

[0041] This embodiment is another preferred implementation method. By studying the slope of the depositional zone and the depositional characteristics of debris flows in gullies, the depositional range of debris flows in gullies related to the relative elevation difference and the slope of the depositional fan is constructed, and the prediction results are more reliable and applicable. The invention will now be described with reference to specific examples: The investigation identified 33 gullies where debris flows have occurred, including a cluster of gully-type debris flows in Niedu Township, Jiangxi Province in 2009; a gully-type debris flow in Shunchang County, Fujian Province on June 18, 2010; a gully-type debris flow in Yanping, Fujian Province on June 18, 2010; a gully-type debris flow in Pucheng, Fujian Province on July 9, 2019; a gully-type debris flow in Ji'an County, Zhejiang Province on August 9, 2019; and a gully-type debris flow in Changtan Town, Wanzhou, Chongqing Province in 2023.

[0042] First, by obtaining contour lines of the debris flow basin and measuring the elevation difference from the mouth of each gully to the highest point of the basin using AutoCAD software, the elevation difference from the potential source point of the gully-type debris flow to the gully mouth was calculated. The furthest horizontal movement distance of the unstable source was calculated to obtain the farthest deposition location. The distance from the furthest deposition area to the gully mouth was measured. Through field surveys and by measuring the slope from the gully mouth to the gentler area along the main gully direction using contour lines, the slope of the gully-type debris flow deposition area was obtained, and the deposition spread angle was calculated. By measuring the distance from the furthest deposition area to the gully mouth and combining it with the deposition spread angle, the distribution range of the debris flow deposition was obtained.

[0043] The parameters of debris flows in 33 gullies and the calculated horizontal movement distance L, deposition distance L' and diffusion angle R of the deposition zone are shown in Table 1.

[0044] Table 1

[0045]

[0046] As can be seen from Table 1: By combining the model predicting the furthest horizontal movement distance of debris flows with the model predicting the diffusion angle, the predicted furthest horizontal distance is larger than the actual furthest horizontal movement distance, with an error ranging from -24.2% to 38.3%, and an absolute average error of 14.2%. The predicted maximum diffusion angle is also larger than the actual diffusion angle, with an error ranging from -17.1% to 20.0%, and an absolute average error of 9.2%. According to the results in Table 1, it can be seen that the furthest deposition distance of gully-type debris flows calculated by the deposition range prediction model is not significantly different from the actual debris flow deposition distance, with a small error, and is suitable for predicting the outflow distance of gully-type debris flows; similarly, the diffusion angle of gully-type debris flows calculated by the deposition range prediction model is not significantly different from the actual diffusion angle of gully-type debris flows, with a small error, and is suitable for predicting the diffusion angle of gully-type debris flows.

[0047] The calculated depositional fan area is not significantly different from the actual area, with an error ranging from -37.3% to 44.6%, and an absolute average error of 22.3%. Therefore, the coupled prediction model of the furthest depositional area of ​​gully-type debris flows and the prediction model of the depositional diffusion angle of gully-type debris flows can effectively predict the depositional influence range of gully-type debris flows.

Claims

1. A method for predicting the depositional extent of gully-type debris flows, characterized in that, Includes the following steps: Step 1: Obtain contour data of the debris flow basin, draw longitudinal profile of the basin based on the contour data, determine the highest point of the basin channel and the location of the channel mouth where the debris flow begins to expand on the longitudinal profile, and determine the elevation difference between the highest point of the channel and the channel mouth. Step 2: Calculate the elevation difference between the center point of the potential instability source and the mouth of the channel based on the elevation difference between the highest point of the channel and the channel mouth; Step 3: Calculate the horizontal projection distance from the center point of the unstable debris source to the leading edge of the final debris flow deposition, determine the position of the leading edge of the final debris flow deposition, and then measure the distance from the mouth of the gully to the leading edge position. Step 4: Determine the slope of the depositional area through field surveys, and calculate the diffusion angle of the depositional fan based on the slope of the depositional area; Step 5: Based on the distance from the mouth of the gully to the foremost edge and the diffusion angle of the debris flow fan, predict the extent of the debris flow depositional fan.

2. The method for predicting the deposition range of gully-type debris flows according to claim 1, characterized in that: In step two, the height difference between the center point of the potential unstable material source and the mouth of the trench is calculated using Equation 1; Formula 1 Where: Hp—the elevation difference between the center point of the potential unstable material source and the mouth of the channel, m; H—the elevation difference between the highest point of the channel and the mouth of the channel, m.

3. The method for predicting the deposition range of gully-type debris flows according to claim 1, characterized in that: In step three, the horizontal projection distance from the center point of the unstable material source to the leading edge of the final debris flow accumulation is calculated using Equation 2. Formula 2 Where: L——the horizontal projection distance from the center point of the unstable material source to the leading edge of the final debris flow deposition, m; Hp——the elevation difference between the center point of the potential unstable material source and the mouth of the gully, m.

4. The method for predicting the deposition range of gully-type debris flows according to claim 1, characterized in that: In step four, the diffusion angle of the stacked fan is calculated using Equation 3; Formula 3 In the formula: R—diffusion angle of the stacking fan, degrees; —Slope of the accumulation zone, degrees.

5. The method for predicting the deposition range of gully-type debris flows according to claim 1, characterized in that: In step four, determining the slope of the depositional area through field investigation refers to selecting three representative profiles on the surface of the depositional fan in the field for actual measurement and taking the average value.

6. The method for predicting the deposition range of gully-type debris flows according to claim 1, characterized in that: In step five, when predicting the extent of the debris flow depositional fan, a fan-shaped area is drawn as the predicted depositional extent, with the gully mouth as the vertex, the distance from the gully mouth to the foremost edge as the radius, and the diffusion angle of the depositional fan as the opening angle.

7. An application of a method for predicting the depositional extent of gully-type debris flows, characterized in that, The method for predicting the deposition range of gully-type debris flows as described in any one of claims 1-6 includes the following steps: S1. Predict and determine the extent of debris flow depositional fans as early warning zones; S2. Install rain gauges, mud level or ground acoustic monitoring sensors in the upstream gully of the warning area, and set warning thresholds related to the activation of potential unstable material sources. S3. When the monitoring data exceeds the warning threshold, a debris flow warning message is automatically generated and released.

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