Calculation Method, System and Electronic Device for Debris Flow Discharge in Alpine Region

Abstract

The present invention relates to the technical field of debris flow flow, and provides a method, system and electronic equipment for calculating the debris flow flow in a high-cold area. The method comprises: obtaining meteorological data including surface air temperature and hourly precipitation of a monitoring station in the high-cold area, and obtaining snowfall and rainfall based on the meteorological data; respectively calculating snow runoff data, runoff data generated by glacier melting, debris flow gully mouth flow data driven by rainfall and groundwater flow data of the monitoring station in the high-cold area based on the meteorological data, the snowfall and the rainfall; calculating the total runoff data of the debris flow flow of the monitoring station in the high-cold area according to the snow runoff data, runoff data generated by glacier melting, debris flow gully mouth flow data driven by rainfall and groundwater flow data of the monitoring station in the high-cold area.

Description

Technical Field

[0001] The invention relates to the technical field of debris flow flow, and in particular to a calculation method, system and electronic equipment for debris flow flow in alpine areas. Background Art

[0002] Due to the high altitude, cold climate, undulating terrain and fragile ecological environment, alpine areas are prone to debris flow disasters. Debris flows are characterized by sudden outbreaks, fast flow rates, concentrated energy and strong destructive power, posing a serious threat to the safety of life and property of mountain residents and infrastructure such as transportation and energy. Traditionally, debris flows in mountainous areas are mostly driven by heavy rainfall; however, in alpine areas, snowmelt and icemelt often become important triggering factors, especially when rain and snow interact and the temperature rises sharply, the disaster process is more complicated, and the scale and impact range of the debris flows formed are often significantly increased.

[0003] At the same time, observation data in alpine areas are extremely scarce: due to the harsh climate and inconvenient transportation, the meteorological station network is small and not representative enough, and the terrain is undulating and the vertical difference in temperature is obvious, which makes it difficult for the traditional rain-source debris flow model (mainly based on rainfall thresholds and empirical judgment) to accurately describe the ice and snow replenishment process in alpine areas. Although the hydrological model can provide a basic framework for the precipitation-runoff relationship, the snow accumulation process (snow cover and melting, snow and ice energy balance, etc.) in the alpine areas shows strong spatiotemporal variation. It is often impossible to obtain accurate snow volume and melting time series by relying on only a small number of stations or simple interpolation.

[0004] In addition, with global warming, glaciers in high-cold regions are retreating and permafrost degradation is intensifying, leading to an increasingly prominent impact of mountain ice and snow on hydrological processes and debris flow triggering. In order to improve the simulation and prediction accuracy of these complex processes, it is necessary to use multi-source remote sensing (such as optical, microwave, etc.) and ground observation fusion to dynamically correct the evolution of snow and ice reserves, and provide more accurate input conditions for the formation and flow process of snowmelt or icemelt driven debris flows.

[0005] The current methods for predicting debris flow disasters in alpine areas are mostly based on precipitation and temperature thresholds to distinguish between rainfall-type and snowmelt-type triggering mechanisms. However, due to the particularity of the mountainous environment in alpine areas and the limited monitoring data, there is still a lack of scientific and effective simulation and identification of debris flow processes triggered by rain and snow fusion. In general, the existing methods have the following main shortcomings:

[0006] (1) Hydrological models cannot accurately simulate the hydrodynamic process of debris flows

[0007] Currently, the hydrodynamic behavior of debris flows is often simplified to ordinary runoff or shallow flows, which cannot reflect the strong coupling effect among particles, mud, and the water phase. The runoff generation and concentration algorithms in hydrological models focus on the precipitation-runoff relationship and lack specific descriptions of debris flow processes with high sediment content and complex dynamic characteristics, resulting in large deviations in the estimation of disaster scale and flow velocity.

[0008] (2) There are biases in snowmelt simulation, seriously affecting the estimation of snowmelt runoff

[0009] In alpine regions, the snow cover distribution and dynamic processes have strong spatial heterogeneity and seasonal variations. There are large uncertainties in the estimation of snow cover, snow depth, or snow water equivalent based on traditional meteorological station interpolation. In addition, the vertical temperature change, snow drift process, and local microclimate effects caused by complex terrain all lead to insufficient simulation accuracy of snow volume and snowmelt processes in the model, making it difficult to accurately quantify the snowmelt runoff in alpine regions.

[0010] (3) Debris flow models are mainly for rainfall-driven types and lack systematic applicability to rain-snow mixed triggering

[0011] Most existing debris flow forecasting and risk assessment models are based on a single rainfall triggering condition and insufficiently consider rain-snow mixed driving and the re-melting characteristics of snow cover. In alpine regions, the peak flows caused by snowmelt or sudden rain-snow mixing usually show characteristics such as uneven spatio-temporal distribution and unstable starting critical conditions. It is difficult for the model to take into account debris flow source supply, snowmelt erosion, and hydrodynamic evolution, making the identification and prediction of rain-snow interaction-triggered debris flows still face great challenges. Summary of the Invention

[0012] In view of the above problems, the present invention is proposed to provide a method, device, and electronic device for calculating the debris flow discharge in alpine regions to overcome the above problems.

[0013] In one aspect of the present invention, a method for calculating the debris flow discharge in alpine regions is provided, and the method includes:

[0014] Obtain meteorological data including surface air temperature and hourly precipitation at monitoring stations in alpine regions, and obtain snowfall and rainfall based on the meteorological data;

[0015] Based on the meteorological data, the snowfall, and the rainfall, calculate the snowmelt runoff data, the runoff data generated by glacier melting, the debris flow gully mouth discharge data driven by rainfall, and the groundwater discharge data at the monitoring stations in alpine regions respectively;

[0016] Calculate the total runoff data of the debris flow discharge at the monitoring stations in alpine regions according to the snowmelt runoff data, the runoff data generated by glacier melting, the debris flow gully mouth discharge data driven by rainfall, and the groundwater discharge data at the monitoring stations in alpine regions.

[0017] Preferably, obtaining the snowfall amount and rainfall amount based on the meteorological data includes:

[0018] Using the hyperbolic tangent function and the surface air temperature in the meteorological data to calculate the conditional frequency of snowfall;

[0019] Using the conditional frequency of snowfall and the hourly precipitation amount in the meteorological data to calculate the snowfall amount and rainfall amount of the alpine monitoring station respectively.

[0020] Preferably, calculating the snowmelt runoff data of the alpine monitoring station based on the meteorological data, the snowfall amount and the rainfall amount includes:

[0021] Based on the degree-day factor model and the surface air temperature in the meteorological data, calculate the potential snowmelt amount at the current moment, and calculate the actual snowmelt amount at the current moment according to the potential snowmelt amount at the current moment;

[0022] Based on the surface air temperature in the meteorological data, the snowfall amount and the actual snowmelt amount at the current moment, calculate the snow storage amount at the current moment;

[0023] Based on the surface air temperature in the meteorological data, the rainfall amount and the snow storage amount at the current moment, calculate the meltwater amount in the snow layer at the current moment;

[0024] Based on the surface air temperature in the meteorological data, the rainfall amount, the actual snowmelt amount at the current moment and the meltwater amount in the snow layer at the current moment, calculate the snowmelt runoff data of the alpine monitoring station at the current moment.

[0025] Preferably, calculating the runoff data generated by glacier melting at the alpine monitoring station based on the meteorological data, the snowfall amount and the rainfall amount includes:

[0026] Based on the degree-day factor model and the surface air temperature in the meteorological data, calculate the melting amount of the glacier without debris cover and the melting amount of the glacier with debris cover respectively;

[0027] Based on the melting amount of the glacier without debris cover and the melting amount of the glacier with debris cover, calculate the total glacier melting amount;

[0028] Based on the total glacier melting amount and the configured glacier runoff coefficient, calculate the runoff data generated by glacier melting at the alpine monitoring station.

[0029] Preferably, calculating the flow data at the debris flow gully mouth driven by rainfall at the alpine monitoring station based on the meteorological data, the snowfall amount and the rainfall amount includes:

[0030] Based on the debris flow erosion intensity and the debris flow movement runoff equation of the alpine monitoring site, the runoff height, runoff velocity and runoff depth of the debris flow movement are obtained;

[0031] Based on the runoff height, runoff velocity and runoff depth of the debris flow movement, the debris flow gully mouth flow data driven by rainfall at the alpine monitoring site is calculated.

[0032] Preferably, calculating the groundwater flow data of the alpine monitoring site based on the meteorological data, the snowfall amount and the rainfall amount includes:

[0033] The groundwater depth and soil properties of the alpine monitoring site, and based on the groundwater depth and soil properties, the groundwater recharge amount at the current moment is calculated;

[0034] Based on the groundwater recharge amount at the current moment, the groundwater flow into the main river at the current moment of the alpine monitoring site is calculated.

[0035] Preferably, according to the snowmelt runoff data, the runoff data generated by glacier melting, the debris flow gully mouth flow data driven by rainfall and the groundwater flow data of the alpine monitoring site, calculating the total runoff data of the debris flow flow at the alpine monitoring site includes:

[0036] By performing a sum operation on the snowmelt runoff data, the runoff data generated by glacier melting, the debris flow gully mouth flow data driven by rainfall and the groundwater flow data, the total runoff data of the debris flow flow at the alpine monitoring site is obtained.

[0037] Another aspect of the present invention provides a calculation system for the debris flow flow in the alpine region, including:

[0038] An acquisition module for acquiring meteorological data including surface air temperature and hourly precipitation of an alpine monitoring site, and obtaining the snowfall amount and rainfall amount based on the meteorological data;

[0039] A first calculation module for respectively calculating the snowmelt runoff data, the runoff data generated by glacier melting, the debris flow gully mouth flow data driven by rainfall and the groundwater flow data of the alpine monitoring site based on the meteorological data, the snowfall amount and the rainfall amount;

[0040] A second calculation module for calculating the total runoff data of the debris flow flow at the alpine monitoring site according to the snowmelt runoff data, the runoff data generated by glacier melting, the debris flow gully mouth flow data driven by rainfall and the groundwater flow data of the alpine monitoring site.

[0041] Preferably, the obtaining module is specifically configured to calculate the conditional frequency of snowfall by using the hyperbolic tangent function and the surface air temperature in the meteorological data; and calculate the snowfall amount and rainfall amount of the alpine monitoring station by using the conditional frequency of snowfall and the hourly precipitation amount in the meteorological data.

[0042] Another aspect of the present invention provides an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor; when the computer program is executed by the processor, the steps of the method for calculating the debris flow discharge in the alpine region as described above are implemented.

[0043] The method, system, and electronic device for calculating the debris flow discharge in the alpine region provided by the embodiments of the present invention obtain meteorological data including surface air temperature and hourly precipitation amount of the alpine monitoring station, and obtain the snowfall amount and rainfall amount based on the meteorological data; calculate the snowmelt runoff data, runoff data generated by glacier melting, rainfall-driven debris flow gully mouth discharge data, and groundwater flow data of the alpine monitoring station respectively based on the meteorological data, the snowfall amount, and the rainfall amount; calculate the total runoff data of the debris flow discharge of the alpine monitoring station according to the snowmelt runoff data, runoff data generated by glacier melting, rainfall-driven debris flow gully mouth discharge data, and groundwater flow data of the alpine monitoring station. The present invention is a method for calculating the debris flow discharge in the alpine region that can couple the dynamic changes of snow cover and take into account the debris flow dynamics characteristics, so as to better simulate and predict the peak flow and disaster-forming process triggered by "rain, snow (ice) mixture". By integrating multi-source remote sensing correction into the snowmelt calculation of the hydrological model and coupling the snow and ice runoff with the debris flow model, the limitation of the existing debris flow model limited to rainfall-driven can be overcome, and more scientific and effective technical support can be provided for the prevention and emergency management of debris flow disasters in alpine regions with scarce data.

[0044] In summary, the present invention has the following beneficial effects:

[0045] (1) Accurately depict the debris flow mechanism triggered by snowmelt - by coupling the snowmelt process model in the debris flow dynamics model, comprehensively considering the influence of ice and snow supply on the peak flow and start-up hour, and overcoming the limitation of the traditional model only for rainfall-triggered. This method can effectively identify the triggering conditions of "rain, snow, ice superposition" and pure snowmelt type, and significantly improve the accuracy and timeliness of debris flow discharge prediction in alpine regions;

[0046] (2) Dynamic update and multi-source data fusion - With the help of remote sensing products and ground monitoring data, the snow cover and snowmelt process are corrected in real-time or near real-time to make up for the data insufficiency caused by the scarcity of stations and complex terrain in alpine regions. The dynamic update of snow cover status using multi-source remote sensing data makes the debris flow model more sensitive in capturing extreme weather or rapid warming events, further improving the accuracy and stability of flow simulation;

[0047] (3) Support for disaster warning and decision-making - It can be seamlessly connected to the regional emergency management system or warning platform. Combining the quantitative simulation of debris flow scale and influence range, it provides scientific support for the warning and disposal of rain-snow-ice mixed disasters in alpine regions. Through the refined coupling of ice / snow-runoff mechanism and debris flow dynamics, the present invention has great application value for debris flow risk assessment and disaster prevention and mitigation planning in the complex environment of alpine regions, significantly making up for the deficiencies of existing debris flow models in alpine regions.

[0048] The above description is only an overview of the technical solution of the present invention. In order to understand the technical means of the present invention more clearly, it can be implemented according to the content of the specification. And in order to make the above and other purposes, features and advantages of the present invention more obvious and understandable, the specific embodiments of the present invention are given below. Description of the Drawings

[0049] By reading the detailed description of the preferred embodiments below, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only for the purpose of showing the preferred embodiments and are not considered to be a limitation of the present invention. In the drawings:

[0050] Figure 1 It is a flowchart of the calculation method for debris flow discharge in alpine regions proposed by an embodiment of the present invention;

[0051] Figure 2 It is a schematic diagram of the formation process of mountain torrent debris flow in alpine regions proposed by an embodiment of the present invention;

[0052] Figure 3 It is a schematic diagram of the dynamic update of snow cover simulation deviation and remote sensing products in alpine regions proposed by an embodiment of the present invention;

[0053] Figure 4 It is a schematic diagram of the structure of the calculation system for debris flow discharge in alpine regions proposed by an embodiment of the present invention. Detailed Embodiments

[0054] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present disclosure can be more thoroughly understood and the scope of the present disclosure can be completely conveyed to those skilled in the art.

[0055] Those skilled in the art of the present technology can understand that, unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meaning as the general understanding of those of ordinary skill in the art to which the present invention pertains. It should also be understood that terms such as those defined in a general dictionary should be understood to have a meaning consistent with their meaning in the context of the prior art, and will not be interpreted in an idealized or overly formal sense unless specifically defined.

[0056] Figure 1 It is a flowchart of a method for calculating debris flow discharge in alpine regions according to an embodiment of the present invention, as Figure 1 shown, including:

[0057] Step S101: Obtain meteorological data including surface air temperature and hourly precipitation at monitoring stations in alpine regions, and obtain snowfall and rainfall based on the meteorological data;

[0058] In one embodiment of the present invention, obtaining snowfall and rainfall based on the meteorological data includes:

[0059] Use the hyperbolic tangent function and the surface air temperature in the meteorological data to calculate the conditional frequency of snowfall;

[0060] Use the conditional frequency of snowfall and the hourly precipitation in the meteorological data to calculate the snowfall and rainfall at the monitoring stations in alpine regions, respectively.

[0061] Step S102: Based on the meteorological data, the snowfall, and the rainfall, calculate the snowmelt runoff data, the runoff data generated by glacier melting, the debris flow gully mouth discharge data driven by rainfall, and the groundwater flow data at the monitoring stations in alpine regions, respectively;

[0062] In one embodiment of the present invention, calculating the snowmelt runoff data at the monitoring stations in alpine regions based on the meteorological data, the snowfall, and the rainfall includes:

[0063] Based on the degree-day factor model and the surface air temperature in the meteorological data, calculate the potential snowmelt at the current moment, and calculate the actual snowmelt at the current moment according to the potential snowmelt at the current moment;

[0064] Calculate the current snow storage based on the surface air temperature in the meteorological data, the snowfall amount, and the actual snowmelt amount at the current moment;

[0065] Calculate the meltwater amount in the snow layer at the current moment based on the surface air temperature in the meteorological data, the rainfall amount, and the current snow storage;

[0066] Calculate the current snowmelt runoff data of the alpine monitoring station based on the surface air temperature in the meteorological data, the rainfall amount, the actual snowmelt amount at the current moment, and the meltwater amount in the snow layer at the current moment.

[0067] In an embodiment of the present invention, calculating the runoff data generated by glacier melting at the alpine monitoring station based on the meteorological data, the snowfall amount, and the rainfall amount includes:

[0068] Calculate the melting amount of the glacier without debris cover and the melting amount of the glacier with debris cover respectively based on the degree-day factor model and the surface air temperature in the meteorological data;

[0069] Calculate the total glacier melting amount based on the melting amount of the glacier without debris cover and the melting amount of the glacier with debris cover;

[0070] Calculate the runoff data generated by glacier melting at the alpine monitoring station based on the total glacier melting amount and the configured glacier runoff coefficient.

[0071] In an embodiment of the present invention, calculating the rainfall-driven debris flow gully mouth flow data of the alpine monitoring station based on the meteorological data, the snowfall amount, and the rainfall amount includes:

[0072] Obtain the runoff height, runoff velocity, and runoff depth of debris flow movement based on the debris flow erosion intensity of the alpine monitoring station and the debris flow movement runoff equation;

[0073] Calculate the rainfall-driven debris flow gully mouth flow data of the alpine monitoring station based on the runoff height, runoff velocity, and runoff depth of debris flow movement.

[0074] In an embodiment of the present invention, calculating the groundwater flow data of the alpine monitoring station based on the meteorological data, the snowfall amount, and the rainfall amount includes:

[0075] The groundwater depth and soil properties of the alpine monitoring station, and calculate the current groundwater recharge amount based on the groundwater depth and soil properties;

[0076] Calculate the groundwater flow into the main river at the current moment of the alpine monitoring station based on the current groundwater recharge amount.

[0077] Step S103: Calculate the total runoff data of debris flow at the alpine monitoring site according to the snowmelt runoff data, runoff data generated by glacier melting, debris flow gully mouth flow data driven by rainfall, and groundwater flow data at the alpine monitoring site.

[0078] In an embodiment of the present invention, calculating the total runoff data of debris flow at the alpine monitoring site according to the snowmelt runoff data, runoff data generated by glacier melting, debris flow gully mouth flow data driven by rainfall, and groundwater flow data at the alpine monitoring site includes:

[0079] By performing a sum operation on the snowmelt runoff data, the runoff data generated by glacier melting, the debris flow gully mouth flow data driven by rainfall, and the groundwater flow data, the total runoff data of debris flow at the alpine monitoring site is obtained.

[0080] The present invention provides a method for calculating debris flow discharge in alpine regions, which can couple the dynamic changes of snow cover and take into account the debris flow dynamics characteristics in alpine regions, so as to better simulate and predict the peak discharge and disaster-forming process triggered by "rain-snow (ice) mixture". By integrating multi-source remote sensing correction into the snowmelt calculation of the hydrological model and coupling the snow and ice runoff with the debris flow model, the limitations of existing debris flow models limited to rainfall-driven can be overcome, providing more scientific and effective technical support for debris flow disaster prevention and emergency management in alpine regions with scarce data.

[0081] The present invention provides a method for calculating debris flow discharge in alpine regions considering the dynamic changes of snow cover, as Figure 2 shown, mainly including:

[0082] (001) Snowmelt and ice melt calculation method based on hydrological processes

[0083] Referring to the Degree-Day method in the hydrological model, improve the snowmelt and ice melt mechanism based on the degree-hour factor, and numerically simulate the snow cover and glacier ablation processes in alpine regions; integrate meteorological elements (air temperature, precipitation, etc.) and spatial factors (terrain, slope aspect, etc.) in the model to obtain the snow / ice melt water yield at different time steps in alpine regions.

[0084] (002) Coupled debris flow dynamics model

[0085] Couple the debris flow source, rheological characteristics, and channel hydrodynamics into the calculation results of snowmelt-ice melt runoff to form a comprehensive model integrating "solid-liquid coupled rheology-runoff generation and concentration";

[0086] By considering the debris flow initiation conditions (critical velocity, shear stress, etc.) and the source supply process, simulate the formation, flow, and peak discharge evolution of debris flow.

[0087] (003)Use of a dynamically updated snow cover area product

[0088] With the help of hourly / daily snow cover area (SCA) products that integrate remote sensing and ground observations, perform "dynamic replacement" or "online correction" on the snow processes in model calculations;

[0089] As Figure 3 shown, at each time step or specified period, directly or partially (weighted fusion) apply the actual remote sensing snow distribution to the update of the model snow storage / snow cover, so as to more accurately reflect the actual distribution and ablation of the snow cover.

[0090] (004)Improve the applicability under conditions of coexistence of snowmelt, ice melt and rainfall

[0091] Fully consider the impact of "rain + snow (ice)" mixed recharge on debris flow generation and peak flow, and break through the limitations of traditional single rainfall trigger or single snowmelt trigger;

[0092] Through multi-source data coupling, enhance the ability to represent complex hydrological processes in alpine regions, making the model more robust in the face of drastic temperature changes, ice and snow ablation, and heavy rain weather.

[0093] (005)Improve the simulation accuracy of debris flow discharge

[0094] Through the systematic integration of snowmelt runoff generation, ice melt recharge and rainfall source runoff generation, and based on dynamically corrected snow cover information, improve the simulation accuracy of the debris flow hydrodynamic process and peak flow;

[0095] Ultimately, achieve more reliable prediction and risk assessment of debris flow processes in alpine regions, which can be used for decision-making support in multiple fields such as disaster warning, engineering protection, and regional planning.

[0096] Based on the existing hydrological model's calculation of snow / ice melting, this method more precisely simulates the debris flow discharge process in alpine regions under the triple recharge of "rain, snow, and ice" through snowmelt and ice melt calculation + dynamic snow cover correction + debris flow dynamics coupling, significantly improving the prediction accuracy of debris flow peak flow and evolution. This integrated and dynamically updated numerical simulation scheme will effectively fill the technical gap in the research on debris flow triggered by rain-snow mixture in alpine regions, and has high application value and promotion potential.

[0097] The following details each step of the embodiments of the present invention

[0098] Step 1: Rainfall segmentation

[0099] The present invention uses the hyperbolic tangent function to estimate the grid snowfall amount, and the conditional frequency of snowfall can be calculated by the following formula:

[0100] ;

[0101] In the formula, T avg,t is the surface air temperature at t hours (unit: °C); the specific coefficients a, b, c, and d of the hyperbolic tangent function are obtained by least squares estimation and fitting of the observational data in the Tibetan Plateau and surrounding mountainous areas, and are -49.02, 0.4321, 2.47, and 1 respectively.

[0102] Thus, the snowfall at t hours ( Prcp s,t , mm / hour -1 ) / rainfall ( Prcp r,t , mm / hour -1 ) can be obtained by multiplying the hourly precipitation ( Prcp , mm / hour -1 ) by the snowfall condition frequency F or (1 - F).

[0103] ;

[0104] Step 2: Calculation of the snowmelt runoff at the gully mouth

[0105] Snowmelt

[0106] To simulate snowmelt, the well-established and widely used degree-hour factor modeling (DHF) method is adopted. Referring to the degree-day factor widely used in cryosphere models, the degree-hour factor model is based on the empirical relationship between snowmelt and air temperature. Compared with the energy balance model, the degree-hour factor model is easier to construct and only requires air temperature, which is usually available and easy to interpolate. Based on the degree-hour factor method, the hourly potential snowmelt is calculated by the following formula:

[0107] ;

[0108] In the formula, SM pot,t (unit: mm / hour -1 ) is the potential snowmelt at the t-th hour, DHF s (unit: mm / °C -1 / hour -1 ) is the degree-hour factor determined for the regional snow cover change rate.

[0109] The actual snowmelt is limited by the snow cover at the end of the previous hour, and the calculation formula is:

[0110] ;

[0111] wherein, SM act (unit: mm hour -1 ) is the actual snowmelt volume at the t-th hour, SM t-1 is the snow storage at the (t - 1)-th hour. Then, based on the actual snowmelt volume SM act,t and the snowfall volume Prcp s,t , the snow storage at the end of the (t - 1)-th hour is updated to the current t-th hour. Considering that part of the actual snowmelt volume will refreeze in the snow layer and will not immediately form runoff. When the temperature is below the freezing point, the meltwater frozen in the snow layer at the (t - 1)-th hour will be re-counted into the snow storage at the t-th hour, and the calculation formula is:

[0112] ;

[0113] wherein, SWE t is the snow storage at the t-th hour, SWE t-1 is the snow storage at the (t - 1)-th hour, Prcp s,t is the solid precipitation at the t-th hour, SM act,t is the actual snowmelt volume at the t-th hour, FSWE t-1 is the meltwater frozen in the snow layer at the (t - 1)-th hour; all the above quantities are in units of mm.

[0114] Dynamic update of remote sensing snow cover products

[0115] Considering that there will be large deviations in snow cover simulation, therefore, the remote sensing snow cover area product ( SCA obs , which is a single value throughout 24 hours of the day) is used to replace the result calculated from the snow cover of the previous hour, that is, if both the current snow cover area product of the grid and the grid calculation are in a snow-covered state ( SWE > 0 mm), then the calculation process remains unchanged. If there is a deviation between the calculation result and the remote sensing observation, the remote sensing observation shall prevail for subsequent calculations. All grid points with SWE > 0 in the calculation are the snow cover area of the basin simulation ( SCA model ).

[0116] ;

[0117] When there is an observation: directly overwrite the model result to make the final snow cover ratio at the t-th hour ( SCA model,t ) consistent with the remote sensing ( SCA obs,t ); when there is no observation: the model maintains the original SCAmodel,t values or supplemented by other interpolation methods. Subsequently, the model will use SCA final,t as the result of whether the snow cover at a single grid point in that hour is snow-covered or the "initial snow cover" information for the next hour t+1.

[0118] As Figure 3 shown, once the replacement / fusion is completed, SCA final,t after that, before the start of the (t+1)-th hour, the model will use it as the initial snow cover information:

[0119] ;

[0120] Snowpack freezing

[0121] To describe the ability of the snow layer to refreeze meltwater, a calibrated water storage capacity ( WSWE , unit: mm·mm -1 ) is introduced in the model, which represents the total amount of meltwater (mm) that can be frozen by each mm of snow water equivalent in the snowpack. Therefore, the maximum amount of meltwater that can be frozen by the snow layer ( FSWE max , mm) is limited by the snowpack amount:

[0122] ;

[0123] Subsequently, the amount of meltwater stored in the snow layer and potentially frozen in the next time step can be calculated FSWE t :

[0124] ;

[0125] In the formula, FSWE t is the amount of meltwater in the snow layer at the t-th hour, FSWE max , t is the maximum amount of meltwater that can be frozen by the snow layer at the t-th hour, FSWE t-1 is the amount of meltwater frozen in the snow layer at the (t-1)-th hour, Prcp r,t is the rainfall amount at the t-th hour, SM act,t is the actual snowmelt amount at the t-th hour; all items are in units of mm.

[0126] Snowpack runoff calculation

[0127] The total snowpack amount ( SWE all,t , mm) consists of the snowpack amount and the meltwater that can be frozen in the snow layer, and can be expressed as:

[0128] ;

[0129] where 1 - F glac (dimensionless) represents the proportion of the basin grid cell that is not covered by glaciers. In the present invention, it is assumed that snow accumulation and snowmelt processes occur only on the grid cell area regarded as land; snowfall on glaciers is simulated through the glacier module.

[0130] When the air temperature is above freezing and no more meltwater can be frozen in the snowpack, runoff from the snowpack will occur ( R sm , mm hour -1 ). Its calculation formula is:

[0131] ;

[0132] where Δ FSWE (unit: mm) is the change in the meltwater storage in the snowpack, defined as:

[0133] ;

[0134] Step 3: Glacier runoff at the gully mouth

[0135] Since the debris flow dynamics model usually operates at a spatial resolution of the order of meters, glacier dynamic processes such as ice flow cannot be explicitly resolved in the model. Therefore, in the present invention, the glacier is regarded as "surface melting" that can cover all or part of the grid cell.

[0136] Glacier melting

[0137] Glacier melting is also calculated using the degree - hour factor modeling method. Since there are differences in the melting rates between glaciers covered with debris and those without debris cover, the model sets different degree - hour factors for these two types of glaciers respectively. The hourly melting amount GM DF (unit: mm) of the glacier without debris cover is calculated as follows:

[0138] ;

[0139] where DHF DF (unit: mm ℃ -1 hour -1 ) is the degree - hour factor calibrated for the glacier without debris cover, F DF (dimensionless) is the proportion of the glacier without debris in the grid cell within the glacier coverage ratio ( F glac ).

[0140] Hourly melt of debris-covered glaciers GM DC (mm) is calculated in a similar manner but with a different degree-hour factor:

[0141] ;

[0142] Wherein, DHF DC (unit: mm ℃ -1 hour -1 ) is the degree-hour factor of debris-covered glaciers, F DC (dimensionless) is the proportion of debris-covered glaciers in the grid cell within the glacier coverage ratio.

[0143] Total glacier melt in the grid cell GM all (mm) is obtained by multiplying the sum of the melt of debris-free glaciers and debris-covered glaciers by the glacier coverage ratio.

[0144] ;

[0145] Glacier runoff

[0146] In the present invention, part of the glacier meltwater infiltrates to recharge groundwater, and the remaining part forms runoff. The distribution of these two parts is controlled by a glacier melt runoff coefficient ( RC glac , dimensionless), whose value range is from 0 to 1. Thus, the runoff generated by glacier melt R GM (mm, mm hour -1 ) can be expressed as:

[0147] ;

[0148] Glacier infiltration

[0149] Infiltration of glacier meltwater to recharge groundwater ( GM perc , mm hour -1 ) is defined as:

[0150] ;

[0151] The infiltrated glacier meltwater will converge with the infiltration in the non-glacier soil layer of the grid cell and finally recharge groundwater.

[0152] Step 4: Debris flow movement process

[0153] Vegetation interception

[0154] The empirical formula considering the interception of vegetation cover can be expressed as:

[0155] ;

[0156] Where: I c represents the total vegetation interception; Prcp r,t represents the total rainfall; k = 0.046; ·LAI represents the correction coefficient; LAI is the leaf area index of vegetation; S max represents the maximum vegetation canopy storage.

[0157] ;

[0158] Rainfall infiltration

[0159] For the soil infiltration process under rainfall conditions, the Richards equation expressed by the coupling variables of water content and matrix suction is used to describe:

[0160] ;

[0161] In the formula: t represents time, θ represents the soil water content, ψ represents the soil internal pressure head, z represents the soil thickness, K s represents the soil permeability coefficient, S v represents the water absorption caused by the vegetation roots. Considering the disturbance of the bottom boundary to the infiltration process during the rainfall infiltration of the soil, two different boundary conditions (the first type of Dirichlet BC boundary and the second type of Neumann BC boundary) are used to describe

[0162] ;

[0163] In the formula: θ s represents the saturated soil water content, θ m represents the initial soil water content, I t represents the infiltration intensity, −D( θ ) represents the diffusion coefficient, ∇ θ represents the gradient of the field variable, K( θ ) represents the convection or transport term.

[0164] Channel instability

[0165] The calculation equation for slope stability considering rainfall infiltration conditions can be expressed as follows:

[0166] ;

[0167] In the formula: F s represents the slope stability coefficient, z H represents the soil thickness, c represents the effective cohesion of the soil, φ represents the internal friction angle of the slope, G represents the soil unit weight, σ represents the soil suction stress, p w represents the pore water pressure, γ s represents the dry density of the soil, γ w represents the wet density of the soil, χ represents the suction stress coefficient.

[0168] Overland flow

[0169] The overland flow process under rainfall conditions is described by the Shallow - water equation:

[0170] ;

[0171] In the formula: h represents the overland flow depth, (x, y) represents the overland flow direction, Prcp r,t represents the rainfall intensity, I t represents the saturated infiltration intensity of the soil, g represents the acceleration due to gravity, (u, v) represents the overland flow velocity, z b represents the surface elevation, (S fx , S fy ) represents the frictional resistance experienced by overland flow.

[0172] Debris flow movement

[0173] Based on the traditional Savage - Hutter equation, the influence of source erosion on debris flow movement is considered and can be described as:

[0174] ;

[0175] In the formula: h srepresents the debris flow thickness, (x, y) represents the debris flow movement direction, E represents the debris flow erosion intensity, g represents the acceleration due to gravity, (u, v) represents the debris flow movement speed, (u b , v b ) represents the movement speed at the critical channel interface of the debris flow, z b represents the surface elevation, (S gx , S gy ) represents the frictional resistance at the bottom of the debris flow, c represents the solid volume fraction of the debris flow, p represents the saturation of the eroded material source.

[0176] The rainfall-driven debris flow discharge at the gully mouth ( R rain,t , mm / hour -1 ) can be expressed as:

[0177] ;

[0178] In the formula: dx represents the cross-sectional area of the gully mouth.

[0179] Step 5: Base flow recharge at the gully mouth

[0180] The infiltration of glacial meltwater contributes to groundwater recharge. Groundwater recharge does not occur instantaneously but has a certain time lag, depending on the groundwater depth and soil properties. Its calculation is:

[0181] ;

[0182] In the formula, G chrg,t (mm) and G chrg,t-1 (mm) represent the groundwater recharge amounts at the t-th and (t - 1)-th moments respectively, θ gw (hours) is the lag time constant, w 2,percw (mm) is the amount of water infiltrating from the second soil layer into the third soil layer at the t-th moment.

[0183] ;

[0184] In the formula, R BF,t (mm) and RBF,t-1 is the groundwater flow rate into the main river channel at the current time and at time t-1, K sat (mm / hour -1 )is the hydraulic conductivity of the shallow aquifer, ε (dimensionless) is the specific yield of the shallow aquifer, L gw (m)is the hydrological distance from the sub-basin divide to the main river channel, G chrg (mm)is the groundwater recharge amount entering the shallow aquifer at the current time, β gw (dimensionless)is the base flow attenuation coefficient, SW 3 is the soil moisture content of the third layer, BF thresh is the threshold value of the groundwater flow rate into the main river channel.

[0185] Step 6: Calculation of the total runoff at the gully mouth

[0186] Assume that at time t (or time step), the total runoff or total discharge generated ( R total,t , mm / hour -1 )is composed of snowmelt, ice melt, rainfall runoff and groundwater recharge together.

[0187] ;

[0188] For the method embodiments, for simplicity of description, they are all expressed as a series of action combinations. However, those skilled in the art should know that the embodiments of the present invention are not limited by the described action sequence, because according to the embodiments of the present invention, some steps can be carried out in other sequences or simultaneously. Secondly, those skilled in the art should also know that the embodiments described in the specification are all preferred embodiments, and the actions involved are not necessarily essential for the embodiments of the present invention.

[0189] Figure 4 is a schematic structural diagram of a calculation system for debris flow discharge in alpine regions proposed by an embodiment of the present invention, as Figure 4 shown, including:

[0190] An acquisition module, configured to acquire meteorological data including surface air temperature and hourly precipitation of alpine region monitoring stations, and obtain snowfall amount and rainfall amount based on the meteorological data;

[0191] A first calculation module, configured to calculate the snowmelt runoff data, the runoff data generated by glacier melting, the debris flow gully mouth flow data driven by rainfall, and the groundwater flow data of the alpine region monitoring stations respectively based on the meteorological data, the snowfall amount and the rainfall amount;

[0192] A second calculation module, configured to calculate the total runoff data of debris flow discharge at the alpine monitoring site according to the snowmelt runoff data, runoff data generated by glacier melting, debris flow gully mouth discharge data driven by rainfall, and groundwater flow data of the alpine monitoring site.

[0193] In an embodiment of the present invention, the acquisition module is specifically configured to calculate the conditional frequency of snowfall by using the hyperbolic tangent function and the surface air temperature in the meteorological data; and calculate the snowfall amount and rainfall amount at the alpine monitoring site respectively by using the conditional frequency of snowfall and the hourly precipitation in the meteorological data.

[0194] Another aspect of the present invention provides an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor; when the computer program is executed by the processor, the steps of the method for calculating the debris flow discharge in the alpine region as described above are implemented. For example Figure 1 the steps S101 - S103 shown. Alternatively, when the processor executes the computer program, the functions of each module in the above embodiments of the device for calculating the debris flow discharge in the alpine region are implemented, for example Figure 4 the acquisition module, the first calculation module, and the second calculation module shown.

[0195] In the implementation process of the system embodiment and the device embodiment of the present invention, reference may be made to the above method embodiment, and corresponding technical effects are achieved.

[0196] In addition, those skilled in the art can understand that although some embodiments herein include certain features included in other embodiments rather than other features, the combination of features of different embodiments means that it is within the scope of the present invention and forms different embodiments. For example, any one of the claimed embodiments can be used in any combination.

[0197] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that it is still possible to modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for calculating debris flow in alpine areas, characterized in that: include: Obtaining meteorological data including surface air temperature and hourly precipitation from monitoring stations in high-cold areas, and obtaining snowfall and rainfall based on the meteorological data; Based on the meteorological data, the snowfall and the rainfall, respectively calculate the snow runoff data, the runoff data generated by glacier melting, the debris flow gully flow data driven by rainfall and the groundwater flow data of the monitoring station in the alpine region; Calculate the total runoff data of debris flow at the monitoring station in the alpine region based on the snow runoff data, runoff data generated by glacier melting, rainfall-driven debris flow gully flow data, and groundwater flow data at the monitoring station in the alpine region; Based on the meteorological data, the snowfall and the rainfall, respectively calculating the snow runoff data of the monitoring station in the high-cold area includes: Calculating the potential snowmelt at the current moment based on the degree-time factor model and the surface air temperature in the meteorological data, and calculating the actual snowmelt at the current moment based on the potential snowmelt at the current moment; Calculate the snow reserve at the current moment based on the surface air temperature in the meteorological data, the snowfall amount and the actual snowmelt amount at the current moment; Calculate the amount of meltwater in the snow layer at the current moment based on the surface air temperature in the meteorological data, the rainfall and the snow reserve at the current moment; Based on the surface air temperature in the meteorological data, the rainfall, the actual snowmelt amount at the current moment and the meltwater amount in the snow layer at the current moment, the snow runoff data at the high-cold area monitoring station at the current moment is calculated.

2. The method according to claim 1, characterized in that The snowfall and rainfall amounts obtained based on the meteorological data include: Calculating the conditional frequency of snowfall using a hyperbolic tangent function and the surface air temperature in the meteorological data; The snowfall amount and rainfall amount at the monitoring station in the high-cold area are calculated respectively by using the conditional frequency of snowfall and the hourly precipitation in the meteorological data.

3. The method according to claim 2, characterized in that Calculating the runoff data generated by glacier melting at the alpine region monitoring station based on the meteorological data, the snowfall and the rainfall includes: Based on the degree-time factor model and the surface air temperature in the meteorological data, the melting amount of the glacier without rock cover and the melting amount of the glacier with rock cover are calculated respectively; Calculating total glacier melt based on the melt of the glacier without debris cover and the melt of the glacier with debris cover; Based on the total glacier melt volume and the configured glacier runoff coefficient, the runoff data generated by the glacier melt at the alpine area monitoring station is calculated.

4. The method according to claim 3, characterized in that Calculating the rainfall-driven debris flow gully mouth flow data at the high-cold area monitoring station based on the meteorological data, the snowfall and the rainfall includes: Based on the debris flow erosion intensity and debris flow runoff equation of the monitoring station in the alpine region, the runoff height, runoff velocity and runoff depth of the debris flow are obtained; Based on the runoff height, runoff velocity and runoff depth of the debris flow movement, the rainfall-driven debris flow gully mouth flow data of the alpine region monitoring station is calculated.

5. The method according to claim 4, characterized in that Calculating the groundwater flow data of the monitoring station in the high-cold area based on the meteorological data, the snowfall and the rainfall includes: The groundwater depth and soil characteristics of the monitoring station in the alpine region, and based on the groundwater depth and soil characteristics, calculating the groundwater recharge at the current moment; Based on the groundwater recharge at the current moment, the groundwater flow rate flowing into the main river channel at the high-cold area monitoring station at the current moment is calculated.

6. The method according to claim 5, characterized in that Based on the snow runoff data, glacier melt runoff data, rainfall-driven debris flow gully flow data and groundwater flow data at the monitoring station in the alpine region, the total runoff data of debris flow at the monitoring station in the alpine region is calculated, including: By processing the snow runoff data, the runoff data generated by glacier melting, the debris flow gully flow data driven by rainfall, and the groundwater flow data, the total runoff data of the debris flow at the high-cold area monitoring station is obtained.

7. A system for calculating debris flow in high-cold areas, characterized in that: The system is used to execute the method according to any one of claims 1 to 6, and the system comprises: An acquisition module is used to acquire meteorological data including surface air temperature and hourly precipitation at monitoring stations in high-cold areas, and obtain snowfall and rainfall based on the meteorological data; A first calculation module is used to calculate the snow runoff data, the runoff data generated by glacier melting, the debris flow gully flow data driven by rainfall, and the groundwater flow data of the monitoring station in the high-cold area based on the meteorological data, the snowfall, and the rainfall; The second calculation module is used to calculate the total runoff data of the debris flow at the monitoring station in the alpine area according to the snow runoff data, the runoff data generated by glacier melting, the debris flow gully flow data driven by rainfall, and the groundwater flow data at the monitoring station in the alpine area; Based on the meteorological data, the snowfall and the rainfall, respectively calculating the snow runoff data of the monitoring station in the high-cold area includes: Calculating the potential snowmelt at the current moment based on the degree-time factor model and the surface air temperature in the meteorological data, and calculating the actual snowmelt at the current moment based on the potential snowmelt at the current moment; Calculate the snow reserve at the current moment based on the surface air temperature in the meteorological data, the snowfall amount and the actual snowmelt amount at the current moment; Calculate the amount of meltwater in the snow layer at the current moment based on the surface air temperature in the meteorological data, the rainfall and the snow reserve at the current moment; Based on the surface air temperature in the meteorological data, the rainfall, the actual snowmelt amount at the current moment and the meltwater amount in the snow layer at the current moment, the snow runoff data at the high-cold area monitoring station at the current moment is calculated.

8. The system according to claim 7, characterized in that The acquisition module is specifically used to calculate the conditional frequency of snowfall using the hyperbolic tangent function and the surface air temperature in the meteorological data; and to calculate the snowfall and rainfall at the high-cold area monitoring station using the conditional frequency of snowfall and the hourly precipitation in the meteorological data.

9. An electronic device, characterized in that: It comprises a memory, a processor and a computer program stored in the memory and executable on the processor; when the computer program is executed by the processor, the steps of the method for calculating the debris flow rate in high-cold areas described in any one of claims 1 to 6 are implemented.

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