A debris flow power early warning method

Abstract

The present application belongs to the technical field of geological disaster prevention and mitigation, and relates to a debris flow power early warning method, specifically comprising: obtaining a startable source amount of a debris flow basin and a possible runoff under a forecast rainfall condition, calculating a water-rock mixture density ρ d and a water-rock mixture density ρ h under an extreme hourly rainfall condition of a target channel under the forecast rainfall condition according to the startable source amount and the possible runoff respectively; obtaining a final critical density ρ of a water-rock mixture when a debris flow is started in a main sliding direction, and determining a first early warning level T1 under the forecast rainfall condition in combination with a daily scale water-rock mixture density early warning level determination rule, and determining a second early warning level T2 under the extreme hourly rainfall condition in combination with an hourly scale water-rock mixture density early warning level determination rule; when the first early warning level T1 and the second early warning level T2 are inconsistent, selecting a higher early warning level as a published early warning level T of a target debris flow basin, which can effectively prevent group debris flow disasters.

Description

Technical Field

[0001] This invention belongs to the field of geological disaster prevention and mitigation technology, and relates to geological disaster meteorological early warning, specifically to a debris flow dynamic early warning method. Background Technology

[0002] Meteorological early warning systems for geological disasters, based on rainfall forecasts and other meteorological data, can provide advance warnings of the likelihood of geological disasters before heavy rainfall arrives, buying valuable time for threatened populations to evacuate and mitigating risks. This is a crucial measure for geological disaster prevention and mitigation. Among various geological disasters, debris flows, due to their sudden occurrence and large drainage area, often cause mass casualties, making them a key focus and challenge in meteorological early warning. Furthermore, debris flows are closely related to rainfall infiltration and runoff generation processes. Different watersheds have varying hydrological conditions, resulting in significant differences in the occurrence of debris flows in different valleys within the region. Relying solely on statistical patterns for regional meteorological early warning of debris flows inevitably leads to inaccurate predictions. Therefore, research on meteorological early warning methods for debris flows based on their occurrence mechanisms is urgently needed. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a debris flow dynamic early warning method. Based on the debris flow disaster mechanism, a dynamic early warning model is established for each debris flow gully, and targeted analysis of runoff generation, confluence, and initiation risks is carried out, which will help improve the meteorological early warning capability for debris flow disasters.

[0004] The inventors of this application would like to emphasize that the initiation mechanism of debris flow is complex. Based on the initiation and disaster-causing mechanism of debris flow, simulating the rainfall infiltration and runoff generation and confluence process of each gully within the watershed, and setting targeted early warning indicators are the key to carrying out accurate early warning and forecasting.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] This debris flow dynamic early warning method includes the following steps:

[0007] Step 1: Obtain the available sediment source and the potential runoff under forecasted rainfall conditions in the debris flow basin. Based on the available sediment source and potential runoff, calculate the water-rock mixture density ρ of the target channel under the forecasted daily rainfall conditions. d Density ρ of water-stone mixture under extreme hourly rainfall conditions h ;

[0008] Step 2: Obtain the final critical density ρ of the water-rock mixture when the debris flow in the main sliding direction starts, and determine the first warning level T1 under the forecast daily rainfall conditions by combining the daily water-rock mixture density warning level determination rule, and determine the second warning level T2 under the extreme hourly rainfall conditions by combining the hourly water-rock mixture density warning level determination rule; when the first warning level T1 and the second warning level T2 are inconsistent, select the higher warning level as the warning level T for the target debris flow basin.

[0009] Specifically, the debris flow dynamic early warning method includes:

[0010] ① Obtain the available sediment source in the debris flow basin:

[0011] Based on the debris flow development patterns in the study area, the debris flow development history within the target debris flow channel, and the sediment deposition situation in the channel as determined by on-site investigation, the possible debris flow types are identified, and the amount of initiating sediment source is calculated based on these debris flow types. Specifically, for watersheds where soil-related debris flows are possible, the landslide induced by heavy rainfall to cause slope instability is used as the initiating sediment source; for watersheds where hydraulic debris flows are possible, the portion of sediment deposited within the channel that can be initiated under rainfall conditions is used as the initiating sediment source; for watersheds where both hydraulic and soil-related debris flows are possible, both (i.e., the landslide induced by heavy rainfall to cause slope instability and the portion of sediment deposited within the channel that can be initiated under heavy rainfall conditions) are used as the initiating sediment source.

[0012] In assessing the volume of landslides due to slope instability, the slope is simplified to an infinite slope. Stability calculations are performed on slope elements, and potentially unstable elements are identified. The volume of the landslide due to slope instability is estimated by multiplying the area of ​​the slope element by the average thickness of the landslide. The formula for calculating the volume of the landslide due to slope instability is as follows (2):

[0013] v s1 =∑S i h (2)

[0014] In equation (2), v s1 S represents the volume of unstable soil on the watershed slope under rainfall conditions. i Let h be the area of ​​the i-th slope unit, and h be the average thickness of the sliding body.

[0015] Among them, the amount of material source that can be activated in the ditch under rainfall conditions is determined according to the current maximum flushing volume, that is, the amount of material source that can be activated in the ditch is estimated by using the maximum flushing volume of the accumulated material in the ditch, and determined based on experience.

[0016] ② Calculate the potential runoff under the predicted rainfall conditions.

[0017] The scope of the debris flow basin is determined, and the saturation level of the soil and rock mass, vegetation type, and land use type of the target gully are assessed before heavy rainfall. Hydrological models are used to calculate the potential runoff of the basin under forecast rainfall conditions (including total daily runoff and maximum hourly runoff), and corrections are made based on the impacts of human domestic water discharge and agricultural irrigation within the basin. If runoff monitoring and sediment level monitoring are available for the gully, the potential runoff of the basin is corrected in real time using actual monitoring data from 3 hours before rainfall.

[0018] Calculate the total daily runoff using equation (3), and calculate the maximum hourly runoff using equation (4):

[0019]

[0020]

[0021] In equations (3) and (4), Q d Q represents the total daily runoff. h P is the maximum hourly runoff. d To provide early warning of the forecasted rainfall for the day, P h To provide early warning of the day's hourly extreme rainfall, S represents the maximum possible water retention capacity in the basin, and C... N v is a dimensionless parameter. dw v represents the total daily runoff under precipitation conditions. hw Let A be the total hourly runoff under precipitation conditions, and let A be the catchment area.

[0022] ③ Inversion of critical start-up conditions for debris flow

[0023] Based on the topography of the target debris flow channel, typical profiles were taken along the main channel direction to determine the extent of the catchment area, flow area, and deposition area. For the catchment and flow areas, the initial density ρ0 of the water-rock mixture was initially determined based on field surveys. The extent of the overlying deposition layer was then repeatedly defined as (-d1, d1), (-d2, d2)...(-d...). n d n The starting conditions of debris flow were gradually inverted until the accuracy of the simulated water-rock mixture density met the requirements. Finally, the critical density ρ of the water-rock mixture when debris flow started in the main sliding direction was determined, as shown in Table 1.

[0024] Table 1 Inversion Simulation Design Conditions

[0025]

[0026]

[0027] ④ Based on the available material source and potential runoff, calculate the density ρ of the water-rock mixture under the predicted daily rainfall conditions for the target channel. d Density ρ of water-stone mixture under extreme hourly rainfall conditionsh Among them, the formula for calculating the density of the water-stone mixture under the forecast daily rainfall condition is as follows (5), and the formula for calculating the density of the water-stone mixture under the extreme hourly rainfall condition is as follows (6):

[0028]

[0029]

[0030] In equations (5) and (6), ρ d ρ is the density of the water-stone mixture on a daily scale. h The density of the water-stone mixture on an hourly scale; ρ W ρ is the density of the water. s v represents the particle density of the packing. dw v represents the total daily runoff under rainfall conditions; hw v represents the total hourly runoff under rainfall conditions; s1 The volume of the landslide body due to slope instability under rainfall conditions is calculated using equation (1); v s2 The volume of material source that can be activated in the ditch under rainfall conditions is estimated by the maximum amount of material flushed out of the ditch at one time. Based on experience, α and β are the actual activation ratios.

[0031] ⑤ Determine early warning indicators

[0032] The density ρ of the water-stone mixture under the predicted daily rainfall conditions d The numerical range is the first primary judgment rule, as shown in the following formula (7) to preliminarily determine the daily-scale warning level T. 0d The daily warning level T was determined by comparing the total daily runoff with the historical maximum runoff in the basin. 0d Adjustments were made to determine the first warning level, T1, based on the predicted rainfall conditions for the day.

[0033] Density ρ of water-stone mixture under extreme hourly rainfall conditions h The numerical range is the second main judgment rule, as shown in the following formula (8) to preliminarily determine the hourly scale warning level T. 0h The hourly warning level T was determined by comparing the hourly maximum runoff with the historical maximum runoff of the watershed. 0h Adjustments were made to determine the second warning level, T2, under extreme hourly rainfall conditions;

[0034]

[0035]

[0036] In equations (7) and (8), T 0d T is the daily-scale warning level determined under the first primary judgment rule. 0hThe hourly-scale warning level is determined under the second primary judgment rule; ρ is the final critical density of the water-rock mixture when the debris flow starts in the main sliding direction. d To predict the density of the water-stone mixture under daily rainfall conditions, ρ h The density of the water-stone mixture under extreme hourly rainfall conditions.

[0037] Among them, the solar-scale early warning level T 0d The adjustment is as follows: the density ρ of the water-stone mixture on the daily scale. d Within a specific range, if the total daily runoff exceeds the historical maximum runoff in the basin, the daily-scale warning level T will be determined based on the predicted daily rainfall conditions. 0d The alert level has been raised by one level to T1, the highest warning level.

[0038] For hourly warning level T 0h The adjustment is as follows: when the hourly density ρ of the water-stone mixture is... h Within a specific range, if the hourly runoff exceeds the historical maximum runoff of the watershed, the hourly-scale warning level T under the determined extreme hourly rainfall conditions will be adjusted. 0h The alert level has been raised by one level to T2, the second warning level.

[0039] Specifically,

[0040] When performing daily-scale early warning calculations, the daily-scale density ρ of the water-rock mixture is... d Greater than 1.2t / m 3 The minimum of the two values, 0.8ρ, is less than or equal to 1.8t / m. 3 When the minimum of the two values ​​in 1.2ρ is reached, if the total daily runoff exceeds the historical maximum runoff of the basin, then the daily-scale warning level T calculated by equation (7) will be adjusted. 0d The alert level has been raised by one level (i.e., the blue alert is changed to a yellow alert, and the yellow alert is changed to an orange alert).

[0041] When performing hourly-scale early warning calculations, when the hourly-scale density ρ of the water-stone mixture... h Greater than 1.4 t / m 3 The minimum of the two values, 1.2ρ, is less than or equal to 2.0t / m. 3 When the minimum of the two values ​​in 1.8ρ is reached, if the hourly maximum runoff exceeds the historical maximum runoff of the basin, then the hourly-scale warning level T calculated by equation (8) will be adjusted. 0h The alert level has been raised by one level (i.e., the blue alert is changed to a yellow alert, the yellow alert is changed to an orange alert, and the orange alert is changed to a red alert).

[0042] When the first warning level T1 and the second warning level T2 are inconsistent, the higher warning level shall be selected as the warning level T for the target debris flow basin.

[0043] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0044] The technical solution adopted in this invention fully considers the generation, confluence, and runoff effects of heavy rainfall in a watershed, which can significantly improve the accuracy of debris flow early warning at the regional scale. The early warning model established using this technical solution has the characteristics of requiring few input parameters and being easy to apply. It can provide refined debris flow meteorological early warning and forecasting for gullies with incomplete or no monitoring equipment based on rainfall monitoring and forecasting data. In particular, it can compensate for the lack of monitoring capabilities in gullies that are not prone to debris flow. By carrying out debris flow early warning and forecasting on a watershed-by-watershed basis at the regional scale, it is possible to effectively prevent cluster debris flow disasters. Attached Figure Description

[0045] The accompanying drawings are incorporated in and form part of this specification, and together with the description serve to explain the principles of the invention.

[0046] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0047] Figure 1 A flowchart of a debris flow dynamic early warning method provided by the present invention;

[0048] Figure 2 This is a diagram showing the early warning results of the slope unit provided in an embodiment of the present invention;

[0049] Figure 3 This is a map showing the early warning results for the target debris flow basin finally determined in this embodiment of the invention. Detailed Implementation

[0050] Exemplary embodiments will be described in detail below. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples consistent with some aspects of the invention as detailed in the appended claims.

[0051] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0052] Example

[0053] See Figure 1 As shown, this embodiment provides a debris flow dynamic early warning method, including the following steps:

[0054] Step 1: Obtain the available sediment source and the potential runoff under forecasted rainfall conditions in the debris flow basin. Based on the available sediment source and potential runoff, calculate the water-rock mixture density ρ of the target channel under the forecasted daily rainfall conditions. d Density ρ of water-stone mixture under extreme hourly rainfall conditions h ;

[0055] Step 2: Obtain the final critical density ρ of the water-rock mixture when the debris flow in the main sliding direction starts, and determine the first warning level T1 under the forecast daily rainfall conditions by combining the daily water-rock mixture density warning level determination rule, and determine the second warning level T2 under the extreme hourly rainfall conditions by combining the hourly water-rock mixture density warning level determination rule; when the first warning level T1 and the second warning level T2 are inconsistent, select the higher warning level as the warning level T for the target debris flow basin.

[0056] Specifically, the debris flow dynamic early warning method includes:

[0057] ① Obtain the available sediment source in the debris flow basin:

[0058] Based on the development patterns of debris flows in the study area and historical debris flow surveys within the target watershed, both hydraulic and soil-based debris flows occurred in the region. Field investigations revealed abundant loose sediment within the target gully, providing a large potential source of material for debris flows. Some slopes exhibited poor stability and could potentially destabilize under heavy rainfall, thus providing a source of material for debris flows. Therefore, it was determined that the target gully was likely to experience hydraulic-soil-based debris flows. The initiating material source was determined by combining the portion of sediment deposited within the gully that could be initiated under heavy rainfall conditions with the volume of landslide material from slope instability.

[0059] Input the daily rainfall to conduct slope unit stability calculation and determination under rainfall conditions. Use SINMAP to calculate the regional stability coefficient, overlay the stability coefficient raster layer with the slope unit layer, and count the raster area ratio of each warning level in each slope unit. Let a, b, c, and d represent the raster area ratio of warning levels 1, 2, 3, and 4, respectively. Determine the warning level T of the i-th slope unit according to the following formula (1). ixp It outputs the warning level determination results for each slope unit according to the current standard RGB requirements.

[0060]

[0061] Based on the assessment, three slope units are likely to become unstable under the predicted rainfall conditions (see...). Figure 2 Simplifying the slope to an infinite slope, the formula for calculating the volume of the sliding body due to slope instability is as follows (2):

[0062] v s1 =∑S i h (2)

[0063] In equation (2), v s1 S represents the volume of the landslide body that caused the slope instability in the watershed under rainfall conditions. i Let h be the area of ​​the i-th slope unit, and h be the average thickness of the sliding body.

[0064] ② Calculate the potential runoff under the predicted rainfall conditions.

[0065] The debris flow basin extent was determined, and the soil and rock saturation level in the target gully was assessed as moderate before heavy rainfall. The seepage capacity was determined based on vegetation type and land use type. The potential runoff of the basin under forecast rainfall conditions was calculated using the SCS (Soil Conservation Service) model or other hydrological models. The daily forecast rainfall was 100 mm / d, and the hourly extreme rainfall forecast value was 35 mm / h. The total daily runoff was calculated according to equation (3), and the maximum hourly runoff was calculated according to equation (4).

[0066]

[0067]

[0068] In equations (3) and (4), Q d Q represents the total daily runoff. h P is the maximum hourly runoff. d To provide early warning of the forecasted rainfall for the day, P h To provide early warning of the day's hourly extreme rainfall, S represents the maximum possible water retention capacity in the basin, and C... N v is a dimensionless parameter. dw v represents the total daily runoff under rainfall conditions. hw Let A be the total hourly runoff under rainfall conditions, and let A be the catchment area.

[0069] ③ Inversion of critical start-up conditions for debris flow

[0070] Based on the topography of the target debris flow channel, typical profiles were taken along the main channel direction to determine the extent of the catchment area, flow zone, and deposition zone. For the catchment and flow zones, the density of the water-rock mixture was initially determined to be 1.7 based on field surveys. Using Table 2, different moisture content ranges (-0.1, 0.1) and (-0.05, 0.05) of the overlying depositional layer were defined, and the debris flow initiation conditions were gradually inverted. Finally, the critical density ρ of the water-rock mixture at the initiation of the debris flow in the main sliding direction was determined to be 1.8 t / m³. 3 .

[0071] Table 2 Inversion Simulation Design Conditions

[0072]

[0073] ④ Based on the available material source and potential runoff, calculate the density ρ of the water-rock mixture under the predicted daily rainfall conditions for the target channel. d It is 1.41 t / m 3 Density ρ of water-stone mixture under extreme hourly rainfall conditions h It is 1.81t / m 3 Among them, the formula for calculating the density of the water-stone mixture under the forecast daily rainfall condition is as follows (5), and the formula for calculating the density of the water-stone mixture under the extreme hourly rainfall condition is as follows (6):

[0074]

[0075]

[0076] In equations (5) and (6), ρ d ρ is the density of the water-stone mixture on a daily scale. h The density of the water-stone mixture on an hourly scale; ρ w ρ is the density of the water. s v represents the particle density of the packing. dw v represents the total daily runoff under rainfall conditions; hw v represents the total hourly runoff under rainfall conditions; s1 v represents the volume of unstable soil on the watershed slope under rainfall conditions; s2 The volume of material source that can be activated in the ditch under rainfall conditions; α is 0.3, β is 0.5.

[0077] ⑤ Determine early warning indicators

[0078] The daily-scale warning level T under the condition of daily rainfall is determined by equation (7). 0d A blue alert has been issued because the total daily runoff has exceeded the historical maximum runoff in the basin, raising the daily-scale alert level T. 0d Adjusted to a yellow alert (i.e., the first alert level T1); the alert level T under hourly extreme rainfall conditions is determined by formula (8). 0h The alert level is orange. Since the hourly runoff is less than the historical maximum runoff in the basin, there is no need to adjust the hourly alert level T. 0h The alert level has been adjusted, with the second alert level (T2) now designated as an orange alert.

[0079]

[0080]

[0081] In equations (7) and (8), T 0d T is the daily-scale warning level determined under the first primary judgment rule. 0h The hourly-scale warning level determined under the second primary judgment rule; ρ dThe density of the water-stone mixture under predicted daily rainfall conditions is 1.41 t / m³. 3 , ρ h The density of the water-stone mixture under extreme hourly rainfall conditions is 1.81 t / m³. 3 .

[0082] Since the first warning level T1 and the second warning level T2 are inconsistent, the higher warning level is adopted, and the final warning level for the target debris flow basin is determined to be an orange warning. (See below) Figure 3 Therefore, the technical solution adopted in this embodiment fully considers the effects of watershed generation, confluence, and runoff under heavy rainfall, and can significantly improve the accuracy of debris flow early warning at the regional scale.

[0083] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention.

[0084] It should be understood that the present invention is not limited to the content already described above, and various modifications and changes can be made without departing from its scope. The scope of the present invention is limited only by the appended claims.

Claims

1. A method for mudflow power early warning, characterized in that, The method comprises the following steps: Step 1, obtaining the startable material source amount of the debris flow basin and the possible runoff under the forecast rainfall condition, and calculating the water and stone mixture density ρ of the target channel under the forecast daily rainfall condition according to the startable material source amount and the possible runoff d and the water and stone mixture density ρ under the extreme hourly rainfall condition h ; Step 2, obtaining the final critical density of the water-rock mixture when the debris flow in the main sliding direction starts, and determining the first warning level T1 under the forecast daily rainfall condition according to the daily scale water-rock mixture density warning level determination rule, and determining the second warning level T2 under the extreme hourly rainfall condition according to the hourly scale water-rock mixture density warning level determination rule; when the first warning level T1 and the second warning level T2 are inconsistent, the higher warning level is selected as the published warning level T of the target debris flow basin; The specific process of obtaining the final critical density of the water-rock mixture when the debris flow in the main sliding direction starts in step 2 comprises: Firstly, according to the terrain of the target debris flow channel, a typical profile is taken along the main channel direction to determine the range of the catchment area, the flow area and the accumulation area; Then, according to the field investigation, the initial density of the water-rock mixture is defined as ρ0 for the catchment and flow-through area. Through multiple settings of the range of the overlying accumulation layer (-d1, d1), (-d2, d2)…(-d n , d n ), the starting conditions of the debris flow are gradually inverted until the accuracy of the simulated water-rock mixture density meets the requirements. Finally, the final critical density of the water-rock mixture when the debris flow in the main sliding direction starts is determined; In step 2, the daily scale water-rock mixture density warning level determination rule is: The numerical range of the density of the water-stone mixture under the forecast daily rainfall condition is the first main determination rule, as shown in the following formula (7), and the comparison results of the daily runoff total and the historical maximum runoff of the basin are combined to determine the daily scale early warning level T 0d Adjustment is made to determine the first early warning level T1 under the forecast daily rainfall condition. The hourly scale water-rock mixture density warning level determination rule is: The numerical range of the water-rock mixture density under the extreme hourly rainfall condition is taken as the second main determination rule, and the hourly runoff is compared with the historical maximum runoff of the basin to determine the hourly scale warning level T 0h Adjustment is made to determine the second warning level T2 under the hourly extreme rainfall condition. In formula (7), formula (8), T 0d is the day-scale early warning level determined under the first main determination rule, T 0h is the hour-scale early warning level determined under the second main determination rule; ρ is the final critical density of the water-rock mixture at the start of a debris flow in the main sliding direction, ρ d ρ is the density of the water-rock mixture under the forecast daily rainfall conditions, ρ h ρ is the density of the water-rock mixture under the extreme hourly rainfall conditions.

2. The method of claim 1, wherein, The step 1 specifically comprises: According to the development law of the research area debris flow, the development history of the target debris flow channel, and the accumulation condition of the channel material source determined by the field investigation, the type of the possible debris flow is determined, and the startable material source amount is calculated according to the type of the debris flow; The range of the debris flow basin is determined, the saturation degree of the rock-soil body of the target channel before heavy rainfall is evaluated, the vegetation type and the land use type are determined, and the possible runoff of the basin under the forecast rainfall condition is calculated.

3. The method of claim 2, wherein, The calculation of the startable material source amount according to the type of the debris flow specifically comprises: For the basin where the soil force type debris flow may occur, the sliding body caused by the heavy rainfall induced slope instability is taken as the startable material source; For the basin where the water force type debris flow may occur, the part of the channel material source accumulated in the channel that can be started under the condition of heavy rainfall is taken as the startable material source; For the basin where both the water force type and the soil force type debris flow may occur, the part of the channel material source accumulated in the channel that can be started under the condition of heavy rainfall and the sliding body caused by the heavy rainfall induced slope instability are taken as the startable material source.

4. The method of claim 3, wherein, The calculation formula of the volume of the sliding body caused by the slope instability is as follows: v s1 =∑S i h Equation (2) In formula (2), v s1 is the volume of the unstable soil mass of the slope in the watershed under rainfall conditions, S i is the area of the i-th slope unit, and h is the average thickness of the sliding mass.

5. The method of claim 1, wherein, The possible runoff under the forecast rainfall condition comprises the total daily runoff and the maximum hourly runoff.

6. The method of claim 5, wherein, The calculation formula of the total daily runoff is as follows, and the calculation formula of the maximum hourly runoff is as follows: In equations (3) and (4), Q d Q represents the total daily runoff. h P is the maximum hourly runoff. d To provide early warning of the forecasted rainfall for the day, P h To provide early warning of the day's hourly extreme rainfall, S represents the maximum possible water retention capacity in the basin, and C... N v is a dimensionless parameter. dw v represents the total daily runoff under rainfall conditions. hw Let A be the total hourly runoff under rainfall conditions, and let A be the catchment area.

7. The method of claim 6, wherein, The calculation formula of the water-rock mixture density of the target channel under the forecast daily rainfall condition in step 1 is as follows, and the calculation formula of the water-rock mixture density under the extreme hourly rainfall condition is as follows: in formula (5), formula (6), ρ d is the daily scale water-rock mixture density, ρ h is the hourly scale water-rock mixture density; ρ w is the water body density; ρ s is the bulk body particle density; v dw is the total daily runoff under rainfall conditions; v hw is the total hourly runoff under rainfall conditions; v s1 is the volume of the slope unstable soil body of the watershed under rainfall conditions; v s2 is the volume of the channel startable source under rainfall conditions; α, β are actual starting proportions.

8. The debris flow dynamic warning method according to claim 1, characterized in that, The warning level is adjusted according to the comparison result of the total daily runoff and the historical maximum runoff of the basin, and specifically: ρ d greater than 1.2 t / m 3 the minimum of both 0.8p and 1.2p, and less than or equal to 1.8 t / m 3 the minimum of both 0.8p and 1.2p, and less than or equal to 1.8 t / m 0d the minimum of both 0.8p and 1.2p, and less than or equal to 1.8 t / m The warning level is adjusted according to the comparison result of the hourly runoff and the historical maximum runoff of the basin, and specifically: when the hour-scale water-soil mixture density p h is greater than 1.4 t / m 3 is greater than 1.2 p and less than or equal to 2.0 t / m 3 is greater than 1.8 p, if the maximum hourly runoff exceeds the historical maximum hourly runoff of the basin, the hourly-scale warning level T 0h is increased by 1 level as the second warning level T2.

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