Qinghai-Tibet Plateau frozen soil liquid water content calculation method and system

Abstract

The invention provides a Qinghai-Tibet Plateau frozen soil liquid state water content calculation method and system, and relates to the technical field of frozen soil water content calculation. The method comprises the following steps: collecting meteorological data including precipitation, temperature and evaporation evapotranspiration, and inputting the meteorological data into an improved VIC model to realize real-time calculation of a soil moisture dynamic equation. In the simulation process, the change of the liquid water content and the interaction of environmental factors are considered. And the calculation result is verified by analyzing model output, and the moisture distribution characteristics of the frozen soil region are deeply discussed, so that a scientific basis is provided for water resource management and ecological protection. The method solves the problem that the prior art lacks a refined relation between solid moisture content and temperature established based on an actual measurement observation network and soil texture classification, so that the liquid moisture content of frozen soil cannot be accurately calculated and an existing model cannot be effectively improved under the condition of the Qinghai-Tibet Plateau.

Description

Technical Field

[0001] This invention relates to the field of permafrost moisture calculation technology, and in particular to a method and system for calculating the liquid water content of permafrost in the Qinghai-Tibet Plateau. Background Technology

[0002] The Qinghai-Tibet Plateau is one of the regions most sensitive to climate change under the background of global warming. Its permafrost and seasonally frozen soils are widely distributed, and changes in soil liquid water content directly affect surface energy budget, hydrological cycle, and ecosystem processes. Existing land surface hydrological and energy balance models typically describe permafrost hydrothermal processes through empirical freeze-thaw relationships, correlating soil temperature with soil moisture state to estimate the distribution of liquid and solid water content under different temperature conditions. These methods have certain applicability in mid- and low-latitude regions and under general soil conditions, providing fundamental support for watershed runoff simulation and regional water resource assessment.

[0003] With improved observation capabilities, a relatively systematic soil temperature and humidity observation network has been established in the Qinghai-Tibet Plateau region, acquiring information on soil temperature, moisture content, and soil texture at different spatiotemporal scales. Research trends are gradually shifting from simple empirical relationships to utilizing measured data and soil physicochemical properties to construct hydrothermal coupling relationships that better reflect the characteristics of permafrost regions. Researchers are beginning to attempt to characterize the curves of solid moisture content changing with temperature based on the pore structure and freezing characteristics of soils with different textures, and to embed these parameterized results into large-scale land surface models, aiming to improve the reliability and physical interpretability of simulation results in high-altitude permafrost regions while maintaining computational efficiency.

[0004] However, existing methods often employ uniform or weakly categorized empirical freezing curves, which fail to fully reflect the complex and varied soil texture differences and freeze-thaw mechanisms of the Tibetan Plateau. They also lack texture-specific relationships based on systematic fitting of observation network data, making it difficult to accurately express the quantitative relationship between solid water content and soil temperature. This results in significant estimation errors of liquid water content within the critical temperature range of freeze-thaw transition, consequently affecting the model's overall simulation accuracy of soil thermal conditions, groundwater recharge, surface runoff, and evapotranspiration. Consequently, this hinders the detailed characterization of permafrost hydrological processes and the prediction of future scenarios on the Tibetan Plateau. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, the purpose of this invention is to provide a method and system for calculating the liquid water content of permafrost on the Qinghai-Tibet Plateau. This invention solves the problem that existing technologies lack a refined relationship between solid water content and temperature based on a measured observation network and soil texture classification, thus making it impossible to accurately calculate the liquid water content of permafrost under the conditions of the Qinghai-Tibet Plateau and effectively improve existing models.

[0006] To achieve the above objectives, the present invention provides the following solution: A method for calculating the liquid water content of permafrost in the Qinghai-Tibet Plateau includes: Soil observation data from multiple representative stations on the Qinghai-Tibet Plateau at different times and soil depths were obtained, and the soil observation data were quality controlled and processed to obtain an effective observation dataset of permafrost on the Qinghai-Tibet Plateau. Based on the effective observation dataset of permafrost on the Qinghai-Tibet Plateau, the soils in the permafrost region of the Qinghai-Tibet Plateau are classified to obtain a set of permafrost soil texture types on the Qinghai-Tibet Plateau. Based on the set of soil texture types of permafrost on the Tibetan Plateau, corresponding temperature and moisture content samples were selected from the effective observation dataset of permafrost on the Tibetan Plateau, and a quantitative relationship between solid moisture content and soil temperature was constructed based on the physical laws of permafrost hydrothermal processes. By adjusting and fitting the quantitative relationship under preset physical conditions, a family of relationships between solid moisture content and soil temperature classified by texture is obtained. Based on the aforementioned family of relationships between solid water content and soil temperature classified by texture, and combined with the water storage characteristics and effective pore characteristics that can participate in freezing of different soil textures, the total soil water content is distributed between solid water and liquid water, and a unified calculation relationship for the liquid water content of permafrost on the Qinghai-Tibet Plateau is determined. The unified calculation relationship of liquid water content in the permafrost of the Qinghai-Tibet Plateau is embedded into the VIC model to obtain an improved VIC model; The distribution of liquid water content in the permafrost region of the Qinghai-Tibet Plateau was calculated using the VIC model.

[0007] A system for calculating the liquid water content of permafrost in the Qinghai-Tibet Plateau includes: The dataset observation module is used to acquire soil observation data from multiple representative stations on the Qinghai-Tibet Plateau at different times and different soil depths, and to perform quality control and processing on the soil observation data to obtain an effective observation dataset of permafrost on the Qinghai-Tibet Plateau. The soil classification module is used to classify the soils in the permafrost region of the Qinghai-Tibet Plateau based on the effective observation dataset of permafrost in the Qinghai-Tibet Plateau, and obtain a set of soil texture types in the permafrost region of the Qinghai-Tibet Plateau. The temperature and moisture content sample selection module is used to select corresponding temperature and moisture content samples from the effective observation dataset of permafrost on the Tibetan Plateau based on the set of soil texture types of permafrost on the Tibetan Plateau, and to construct a quantitative relationship between solid moisture content and soil temperature based on the physical laws of permafrost hydrothermal processes. The relationship adjustment and fitting module is used to adjust and fit the quantitative relationship through preset physical conditions to obtain a family of solid moisture content and soil temperature relationships classified by texture. The liquid water content allocation module is used to allocate the total soil water content between solid water and liquid water based on the family of solid water content and soil temperature relationships classified by texture, combined with the water storage characteristics and effective pore characteristics that can participate in freezing of different soil textures, and to determine the unified calculation relationship of liquid water content of permafrost in the Qinghai-Tibet Plateau. The model improvement module is used to embed the unified calculation relationship of liquid water content of permafrost in the Qinghai-Tibet Plateau into the VIC model to obtain the improved VIC model. The liquid water content calculation module is used to calculate the distribution of liquid water content in the permafrost region of the Qinghai-Tibet Plateau using the VIC model.

[0008] The present invention discloses the following technical effects: This invention provides a method and system for calculating the liquid water content of permafrost in the Qinghai-Tibet Plateau. The method includes an improved VIC model that incorporates a temperature-dependent permeability coefficient and dynamic adjustments to the liquid water content, enabling the model to more accurately simulate the distribution and changes of liquid water. This method not only enhances the comprehensive analytical capabilities for changes in precipitation, evaporation, and soil moisture but also contributes to a deeper understanding of the hydrothermal coupling process in permafrost, thus providing decision-makers with more reliable water resource management information. Furthermore, by optimizing the calculation method for liquid water content, the model can support the accuracy of climate change predictions, providing a theoretical basis for ecological restoration and sustainable development. These improvements, combined with advanced soil science and hydrological research, help to effectively address the water shortage and ecological imbalance problems faced by the Qinghai-Tibet Plateau region. Attached Figure Description

[0009] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0010] Figure 1 A flowchart of a method for calculating the liquid water content of permafrost on the Qinghai-Tibet Plateau, provided as an embodiment of the present invention. Detailed Implementation

[0011] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0012] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0013] like Figure 1 As shown, this invention provides a method for calculating the liquid water content of permafrost in the Qinghai-Tibet Plateau, including: Step 100: Obtain soil observation data from multiple representative stations on the Qinghai-Tibet Plateau at different times and different soil depths, and perform quality control and processing on the soil observation data to obtain an effective observation dataset of permafrost on the Qinghai-Tibet Plateau. Step 200: Based on the effective observation dataset of permafrost on the Qinghai-Tibet Plateau, classify the soils in the permafrost region of the Qinghai-Tibet Plateau to obtain a set of soil texture types for permafrost on the Qinghai-Tibet Plateau. Step 300: Based on the set of soil texture types of permafrost on the Qinghai-Tibet Plateau, select corresponding temperature and moisture content samples from the effective observation dataset of permafrost on the Qinghai-Tibet Plateau, and construct a quantitative relationship between solid moisture content and soil temperature based on the physical laws of permafrost hydrothermal processes. Step 400: Adjust and fit the quantitative relationship by preset physical conditions to obtain a family of relationships between solid moisture content and soil temperature classified by texture; Step 500: Based on the family of solid water content and soil temperature relationships classified by texture, and combined with the water storage characteristics and effective pore characteristics that can participate in freezing of different soil textures, the total soil water content is distributed between solid water and liquid water to determine the unified calculation relationship of liquid water content of permafrost in the Qinghai-Tibet Plateau. Step 600: Embed the unified calculation relationship of liquid water content in the permafrost of the Qinghai-Tibet Plateau into the VIC model to obtain the improved VIC model; Step 700: Calculate the distribution of liquid water content in the permafrost region of the Qinghai-Tibet Plateau using the VIC model.

[0014] Furthermore, the specific implementation process of step 100 is as follows: This embodiment will select multiple representative observation points on the Qinghai-Tibet Plateau to ensure coverage of diverse geographical features and ecological environments. These observation stations should be distributed across diverse terrains such as glaciers, lakes, and ridges to improve the representativeness of the collected data. This embodiment will acquire soil temperature, soil moisture content, and soil texture information through long-term monitoring, including manual sampling and automated sensor data collection.

[0015] The soil observation data will undergo quality control and processing. This embodiment will employ a standardized quality control process to ensure the consistency and accuracy of the acquired data. After data acquisition, the precision and accuracy of the measuring equipment should be checked, and outliers and erroneous records should be removed from the data. Soil texture information needs to be classified according to the standard soil classification system for subsequent analysis. Simultaneously, soil temperature and moisture content data need to be processed according to time series to facilitate analysis of changes in soil depth over different time periods.

[0016] Ultimately, a valid observation dataset of permafrost on the Tibetan Plateau was obtained. This embodiment will conduct multi-dimensional analysis on the processed dataset, such as seasonal variations in soil temperature, temporal variations in soil moisture content, and the interrelationships between different soil layer characteristics. To facilitate subsequent modeling and analysis, the dataset will be stored in a consistent format to ensure efficient and accurate subsequent calculations and simulations. The construction of this dataset will provide an important empirical foundation for permafrost research on the Tibetan Plateau and support relevant ecological and environmental management decisions.

[0017] Furthermore, the specific implementation process of step 200 is as follows: This embodiment first extracts soil-related valid observation data from the effective observation dataset of permafrost on the Tibetan Plateau, including soil temperature, soil moisture content, and other physical properties. The extracted data undergoes missing value imputation, outlier removal, and standardization to ensure data validity and consistency. Deleting observations with extreme or unreasonable values ​​helps improve data quality and provides a reliable basis for subsequent classification work, ultimately forming a standardized permafrost observation dataset of the Tibetan Plateau.

[0018] Next, this embodiment develops a soil texture classification standard for the Qinghai-Tibet Plateau region, taking into account its soil characteristics. This standard considers multiple factors, including soil particle size range, water content characteristics, and physical properties. Specifically, the particle size range will be clearly defined according to the standard soil classification system; the description of water content characteristics will utilize water content information from actual observation data; and the physical properties of the soil will comprehensively consider key indicators such as density and porosity. Through these refined standards, this embodiment ensures the formation of a soil texture classification standard that reflects the characteristics of the permafrost region of the Qinghai-Tibet Plateau and provides a framework for subsequent analysis.

[0019] Finally, the standardized permafrost observation dataset of the Tibetan Plateau was classified using the aforementioned soil texture classification standard. This embodiment systematically divides the observation data according to the established classification standard, categorizing soil samples into different texture types, such as sandy soil, clay, and loam. Through the integration and categorization of the classification results, a comprehensive set of soil texture types for the Tibetan Plateau permafrost was formed. This set not only reflects the actual characteristics of the soil but also provides important basic data support for further hydrological model construction and ecological research.

[0020] Furthermore, the specific implementation process of step 300 is as follows: This embodiment will select corresponding temperature and moisture content data from previously acquired valid observation datasets for each soil texture type. This selection process is conducted using classification criteria to ensure that the selected samples accurately reflect the temperature and moisture content characteristics of each soil texture at different depths and time periods. Strict temporal and spatial representativeness of the samples should be ensured to cover potential climate change and soil environmental differences on the Tibetan Plateau.

[0021] Using temperature and moisture content samples for different soil textures, the solid water content is calculated based on the physical laws of permafrost hydrothermal processes. This embodiment employs physical principles from simulation experiments, such as phase transition and heat conduction, to calculate the solid water content of different soil textures at specific temperatures. This involves using theorems or models related to soil temperature and moisture content to derive the solid water fraction. By systematically calculating the selected samples, the solid water content of each soil type is obtained, which forms an important foundation for establishing quantitative relationships.

[0022] Based on the content of solid water, this study utilizes thermophysical experimental data to determine the relationship between solid water and temperature. This embodiment will analyze the characteristics of solid water changes with temperature by collecting existing thermophysical experimental data, deriving preliminary data on the relationship between solid water content and soil temperature. This data relationship reflects the transformation characteristics of water state in permafrost, thus laying the foundation for subsequent statistical analysis. Subsequently, these preliminary relationship data will be subjected to in-depth statistical analysis. Through methods such as regression models or correlation analysis, a quantitative relationship between solid water content and soil temperature will be constructed to support precise research on hydrothermal processes in permafrost, providing solid data support for water resource management and ecological protection.

[0023] Specifically, in establishing a quantitative relationship between solid-state moisture content and soil temperature, this embodiment first determines relevant parameters based on experimental observation data and the physical properties of frozen soil. In the expression for solid-state moisture content, the initial solid-state moisture content constant is obtained experimentally from multiple soil samples, including measurements of samples from major soil textures at different temperatures. Specifically, this constant reflects the maximum solid water content of snow and minute soil moisture at zero degrees Celsius, typically ranging from 0% to 6%. This parameter helps provide the model with the moisture situation under basic conditions.

[0024] Secondly, the energy conversion constant between solid water and temperature reflects the energy demand during the water phase transition process. This constant can be obtained experimentally, with a typical value ranging from 10 to 30, and the specific value varies depending on different soil types and environmental conditions. The importance of this parameter lies in its indication of the sensitivity of temperature changes to the solid water content, providing effective kinetic support for subsequent calculations.

[0025] The correction coefficient reflects the effect of temperature on the solid water content. This coefficient typically ranges from 0 to 5, depending on soil moisture conditions and the external environment. It is used to adjust for differences in the performance of solid water under different environmental standards in the calculation of solid water content, ensuring the accuracy of the model. The exponential coefficient of temperature and its influence on solid water content is selected based on sample data obtained from frozen soil hydrothermal experiments, and is typically between 0.5 and 2.0. The introduction of this exponential coefficient makes the model's response to temperature changes more non-linear, providing adaptability to variable climatic environments. Furthermore, the specific implementation process of step 400 is as follows: The first step in adjusting and fitting the quantitative relationship using preset physical conditions is to establish a set of preset physical conditions for different soil texture types. This embodiment will establish a set of physical conditions applicable to different soil textures based on the specific characteristics of the permafrost on the Qinghai-Tibet Plateau. This set includes, but is not limited to, saturation, maximum frost depth, and temperature range. Saturation describes the moisture content in the soil, helping to analyze changes in solid water content under different moisture conditions; maximum frost depth determines the limiting depth of the permafrost layer, reflecting the impact of soil freezing on moisture distribution; and temperature range indicates the temperature range that can be used for research, ensuring the applicability of the data under logical and realistic conditions.

[0026] Secondly, based on the pre-defined set of physical conditions and the initial quantitative relationship, a fitting process is performed to obtain adjusted and fitted initial parameters. This embodiment will use multiple experimental data points for multivariate regression analysis to combine the quantitative relationship with the pre-defined conditions. All variables will have their initial parameters determined using statistical analysis software; for example, the least squares method can be used to estimate the relationship between solid moisture content and soil temperature. The purpose of this process is to obtain an adjustable initial parameter for the model based on limited observational data, minimizing errors and reflecting different soil texture characteristics.

[0027] Finally, the initial parameters are nonlinearly adjusted using curve fitting techniques. In this embodiment, nonlinear curve fitting methods, such as high-order polynomial regression or spline interpolation, are introduced to more accurately depict the complex relationship between solid moisture content and soil temperature. By combining the initial parameters with preset physical conditions, the model ensures that it not only accurately reflects the data characteristics but also adapts to soil texture changes under different environments. This fitting process generates a family of relationships between solid moisture content and soil temperature, providing rich data support and theoretical basis for subsequent hydrological and meteorological simulations and ecological research, ensuring that the research results have broad practical application value.

[0028] Furthermore, the specific implementation process of step 500 is as follows: When determining a unified calculation relationship for the liquid water content of permafrost on the Qinghai-Tibet Plateau, it is first necessary to analyze the water-storage characteristics and effective porosity characteristics that can participate in freezing of different soil texture types. This embodiment obtains the water characteristics of each soil texture type under different water content states through physical measurements of field soil samples. Water-storage characteristics include the soil's capacity to effectively retain water, which is typically determined by a combination of soil porosity, particle size distribution, and soil structure. Effective porosity characteristics that can participate in freezing refer to the pores in the soil that have a potential impact on water freezing under low-temperature conditions, mainly related to the soil's void distribution and connectivity. Accurate acquisition of these data provides a foundation for subsequent water distribution calculations.

[0029] Next, based on the water retention and effective porosity characteristics of soil texture, the total soil moisture content for each soil texture type is calculated. This embodiment integrates water retention characteristic data, combining water retention capacity with soil moisture content under wet conditions to obtain the total moisture content for each soil texture type. This process utilizes actual observation data and laboratory-measured physical property indicators to ensure that the calculated total moisture content reflects the true soil moisture status. Furthermore, depending on the soil texture, this total moisture content will directly affect the subsequent distribution of liquid and solid water.

[0030] Finally, the total water content of each soil texture type is allocated between solid and liquid water to obtain a unified calculation relationship for the liquid water content of permafrost in the Tibetan Plateau. Combining the family of solid water content and soil temperature relationships categorized by texture, this embodiment will use a mathematical model to evaluate the relative proportions of solid and liquid water. This process involves applying established allocation formulas, considering factors such as soil freeze-thaw cycles and climate change, to ensure the model can adapt to water changes in dynamic soil environments. Ultimately, the consistent calculation relationship obtained through the above steps will provide solid theoretical support for the assessment of liquid water content in permafrost on the Tibetan Plateau and provide an important basis for regional water resource management.

[0031] Specifically, in achieving a unified calculation relationship for the liquid water content of permafrost on the Qinghai-Tibet Plateau, this embodiment first defines a maximum potential liquid water content constant. This constant originates from the liquid water content of different soil samples under the most saturated state, as determined by experimental data, and is typically obtained through laboratory soil moisture measurements. The specific value of this constant will vary depending on local climate conditions and soil texture characteristics. It serves an important function, providing a basic reference for the maximum possible liquid water content and defining an upper limit for the existence of liquid water.

[0032] Subsequently, the energy threshold for liquid water transition is defined as the energy required for liquid water to change state under different temperature conditions. This parameter, also determined experimentally, is typically expressed in joules per kilogram. The range of the energy threshold varies depending on the soil texture, reflecting the energy requirements for the physical state transition. The introduction of this parameter ensures that the model can be appropriately applied to the behavior of liquid water during freezing and thawing processes.

[0033] Next, coefficients characterizing soil structure and its impact on liquid water distribution were obtained through experimental analysis in different soil environments, involving properties such as soil particle size, porosity, and structural stability. These coefficients enable the model to more accurately approximate the actual distribution of liquid water within the soil, ensuring a reasonable liquid water distribution under different wet and dry conditions. Furthermore, soil saturation indicates the proportion of usable water in the soil; overall saturation affects the availability of liquid water and is typically obtained from observational data. Temperature and the exponential coefficient of its influence on liquid water content can be derived through correlation analysis, measuring the sensitivity to changes in liquid water saturation.

[0034] Finally, after constructing a reasonable parameter system, this embodiment will repeatedly verify the calculation relationship of the system through numerical calculation and statistical analysis, combined with the specific conditions of the soil and environmental characteristics, so as to achieve a high degree of matching between the model and the actual situation, and provide a reliable theoretical basis for studying the dynamic changes of liquid water content in permafrost on the Qinghai-Tibet Plateau.

[0035] More specifically, in the unified calculation relationship for the liquid water content of permafrost on the Qinghai-Tibet Plateau, the liquid water content value is 21%, which is the maximum moisture content obtained through laboratory measurements on specific loam samples. The maximum potential liquid water content constant of this soil under saturation is set at 30%, reflecting the upper limit of moisture that the soil can retain under optimal watering conditions. The energy threshold required for liquid water transformation is 5000 joules per kilogram, a value determined through heat transfer experiments, indicating the energy required for permafrost to transform from a solid to a liquid state.

[0036] Furthermore, for this loam sample, the coefficient characterizing soil structure and its influence on liquid water distribution was selected as 0.8, obtained through porosity analysis, revealing how soil microstructure affects water distribution. Soil saturation, obtained from field data, is currently at 90%, indicating a high degree of soil moisture. The soil temperature set for this experiment was -2°C, reflecting the cold climate characteristics of the region. Regarding the exponential coefficient of influence on liquid water content, a value of 1.5 was obtained through statistical analysis, reflecting the degree of influence of temperature changes on the state of liquid water.

[0037] Furthermore, in calculating the distribution of solid and liquid water, this embodiment first determines the initial total water content of each soil type based on the total water content of each soil texture. This process includes the distribution of solid and liquid water, relying on previously obtained soil sample data, and determining the maximum water content of each soil texture through measurement and analysis. The specific soil type will affect its initial total water content value; therefore, at this stage, it is necessary to carefully analyze the physical and chemical properties of each soil type to ensure the high accuracy of the calculated initial moisture state. Through the comprehensive application of laboratory data, this embodiment can effectively and accurately obtain preliminary moisture data for different soil textures.

[0038] Next, this embodiment will utilize a family of relationships between solid water content and soil temperature, categorized by soil texture, to extract estimated solid water content from the total water content of each soil texture type. This process involves a detailed analysis of the state of solid water using an established relationship model, combined with temperature and soil type, to estimate the actual solid water content from the known total water content. This estimation not only references theoretical models but also incorporates actual field observation data, making the calculated solid water content more reliable. During the analysis, the biological and physical reactions of the soil must be considered to ensure that the results reflect the true state of soil water.

[0039] Finally, this embodiment combines the estimated solid water content for each soil texture with the initial total water content to calculate the liquid water content for each soil texture. By subtracting the aforementioned solid water content from the initial total water content, the resulting liquid water content reflects the actual liquid water state of each soil type under current environmental conditions. This statistical analysis not only provides a reference for specific water management and ecological models but also helps in understanding the dynamic cycle of water in different soils under cold climate conditions. Ultimately, the calculation results of solid and liquid water are summarized to form a complete water distribution model, which helps provide a solid theoretical basis and data support for subsequent research on permafrost and hydrological processes.

[0040] Furthermore, the specific implementation process of step 600 is as follows: When embedding the unified calculation relationship of liquid water content in permafrost on the Qinghai-Tibet Plateau into the improved VIC model, the first step in this embodiment is to integrate the aforementioned calculation mechanism of liquid water content to optimize the model's ability to predict soil moisture changes. To achieve this goal, this embodiment introduces relevant parameters and relationships into the VIC model to deepen the understanding of soil behavior and liquid water flow. Specifically, firstly, the calculated liquid water content will replace the traditional water settings in the model, thereby more accurately reflecting the actual changes in water content under current permafrost characteristics and environmental conditions.

[0041] In this improved model, changes in soil moisture rate, precipitation, evapotranspiration, and soil moisture storage are all considered in the calculations. Precipitation is obtained through meteorological data monitoring, including cumulative values ​​of rainwater and snowmelt. Evapotranspiration is estimated based on climatic factors such as temperature and humidity, reflecting the combined effects of water evaporation and plant evapotranspiration. Changes in soil moisture storage are calculated by measuring changes in moisture at soil depth, ensuring the model can adapt to the effects of seasonal variations.

[0042] Building upon this, this embodiment introduces an adjustment coefficient affecting liquid water flow to reflect the characteristics and rate of water flow under different soil conditions. This adjustment coefficient is determined based on the analysis of various soil types and experimental data, ensuring that the model has a certain degree of adaptability under different humidity and temperature conditions. Furthermore, the liquid water content at saturation is also incorporated into the model to directly quantify its adaptability and impact on different soil conditions. The temperature-dependent permeability coefficient is obtained experimentally, reflecting the effect of temperature changes on permeability, and is typically optimized within a specific soil type and temperature range.

[0043] Ultimately, the introduction of these integrated parameters and relationships ensures that the improved VIC model can better adapt to the complex permafrost hydrological characteristics of the Tibetan Plateau, improves the accuracy of simulation results, and provides reliable mathematical support for subsequent research and management of soil moisture behavior.

[0044] Specifically, for example, assuming observations are conducted at a specific location on the Qinghai-Tibet Plateau, the rate of change in soil moisture refers to the increase in soil moisture content from 20% to 25% during the monitoring period. During this process, precipitation is recorded as 10 mm per day, indicating that water replenishment during this period is primarily achieved through rainfall. However, due to climatic conditions, the combined amount of evaporation and transpiration from vegetation is measured at 5 mm per day, showing the extent of water loss.

[0045] Changes in soil moisture storage are also important at this monitoring station; assuming that available soil moisture decreased from 40 mm to 30 mm during the observation period, reflecting a trend of soil drying. To accurately simulate water flow, a moderating coefficient affecting liquid water flow needs to be considered. This coefficient was determined to be 0.1, representing the resistance of soil structure to water flow. Under these conditions, the liquid water content was measured at 25%, representing the amount of water in the soil existing in liquid form. For the saturated state study, the liquid water content of this soil at full saturation was calculated to be 40%, providing a reference for the model's boundary conditions.

[0046] Finally, the effect of temperature on permeability cannot be ignored. In this specific experimental environment, the soil permeability was 0.5 cm / h at 20 degrees Celsius, but decreased to 0.2 cm / h at 5 degrees Celsius, indicating that the soil's water flow capacity is weakened under lower temperature conditions. By comprehensively applying these parameters, the model can more accurately reflect the complex hydrological cycle and soil moisture dynamics in the Qinghai-Tibet Plateau region.

[0047] Furthermore, the specific implementation process of step 700 is as follows: This embodiment will utilize an improved VIC model to calculate the distribution of liquid water content in the permafrost region of the Tibetan Plateau. First, this embodiment will collect and organize meteorological data for the region, including parameters such as precipitation, temperature, humidity, and wind speed. This data typically originates from meteorological stations, remote sensing observations, and field monitoring, ensuring sufficient timeliness and representativeness. By inputting this meteorological data into the improved VIC model, the necessary initial conditions can be provided for the dynamic calculation of liquid water content.

[0048] Next, this embodiment will calculate the soil moisture in the permafrost region of the Qinghai-Tibet Plateau hourly based on the soil moisture dynamic equation defined in the VIC model. Factors considered in this process include the direct impact of precipitation on liquid water, losses through evaporation and evapotranspiration, changes in soil moisture storage, and the effect of temperature on permeability. Through these dynamic interactions, this embodiment can simulate the distribution of liquid water in the soil under different climatic conditions and time periods, and update the soil moisture status in real time.

[0049] Finally, this embodiment will validate the calculation results using historical data and model output, analyzing the spatial variation of liquid water content distribution and its seasonal fluctuations. This process not only helps verify the model's predictive ability but also provides important data support for understanding hydrological processes and ecological management in the Qinghai-Tibet Plateau permafrost region. By comprehensively analyzing these results, we can delve into the behavioral patterns of liquid water in the permafrost environment, providing a scientific basis for local water resource management and ecological protection.

[0050] This implementation also provides a system for calculating the liquid water content of permafrost on the Qinghai-Tibet Plateau, including: The dataset observation module is used to acquire soil observation data from multiple representative stations on the Qinghai-Tibet Plateau at different times and different soil depths, and to perform quality control and processing on the soil observation data to obtain an effective observation dataset of permafrost on the Qinghai-Tibet Plateau. The soil classification module is used to classify the soils in the permafrost region of the Qinghai-Tibet Plateau based on the effective observation dataset of permafrost in the Qinghai-Tibet Plateau, and obtain a set of soil texture types in the permafrost region of the Qinghai-Tibet Plateau. The temperature and moisture content sample selection module is used to select corresponding temperature and moisture content samples from the effective observation dataset of permafrost on the Tibetan Plateau based on the set of soil texture types of permafrost on the Tibetan Plateau, and to construct a quantitative relationship between solid moisture content and soil temperature based on the physical laws of permafrost hydrothermal processes. The relationship adjustment and fitting module is used to adjust and fit the quantitative relationship through preset physical conditions to obtain a family of solid moisture content and soil temperature relationships classified by texture. The liquid water content allocation module is used to allocate the total soil water content between solid water and liquid water based on the family of solid water content and soil temperature relationships classified by texture, combined with the water storage characteristics and effective pore characteristics that can participate in freezing of different soil textures, and to determine the unified calculation relationship of liquid water content of permafrost in the Qinghai-Tibet Plateau. The model improvement module is used to embed the unified calculation relationship of liquid water content of permafrost in the Qinghai-Tibet Plateau into the VIC model to obtain the improved VIC model. The liquid water content calculation module is used to calculate the distribution of liquid water content in the permafrost region of the Qinghai-Tibet Plateau using the VIC model.

[0051] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0052] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for calculating the liquid water content of permafrost in the Qinghai-Tibet Plateau, characterized in that, include: Soil observation data from multiple representative stations on the Qinghai-Tibet Plateau at different times and soil depths were obtained, and the soil observation data were quality controlled and processed to obtain an effective observation dataset of permafrost on the Qinghai-Tibet Plateau. Based on the effective observation dataset of permafrost on the Qinghai-Tibet Plateau, the soils in the permafrost region of the Qinghai-Tibet Plateau are classified to obtain a set of permafrost soil texture types on the Qinghai-Tibet Plateau. Based on the set of soil texture types of permafrost on the Tibetan Plateau, corresponding temperature and moisture content samples were selected from the effective observation dataset of permafrost on the Tibetan Plateau, and a quantitative relationship between solid moisture content and soil temperature was constructed based on the physical laws of permafrost hydrothermal processes. By adjusting and fitting the quantitative relationship under preset physical conditions, a family of relationships between solid moisture content and soil temperature classified by texture is obtained. Based on the aforementioned family of relationships between solid water content and soil temperature classified by texture, and combined with the water storage characteristics and effective pore characteristics that can participate in freezing of different soil textures, the total soil water content is distributed between solid water and liquid water, and a unified calculation relationship for the liquid water content of permafrost on the Qinghai-Tibet Plateau is determined. The unified calculation relationship of liquid water content in the permafrost of the Qinghai-Tibet Plateau is embedded into the VIC model to obtain an improved VIC model; The distribution of liquid water content in the permafrost region of the Qinghai-Tibet Plateau was calculated using the VIC model.

2. The method for calculating the liquid water content of permafrost on the Qinghai-Tibet Plateau according to claim 1, characterized in that, The soil observation data includes: Information on soil temperature, soil moisture content, and soil texture.

3. The method for calculating the liquid water content of permafrost on the Qinghai-Tibet Plateau according to claim 1, characterized in that, The soils in the permafrost region of the Tibetan Plateau are classified based on the effective observation dataset of permafrost on the Tibetan Plateau, resulting in a set of permafrost soil texture types on the Tibetan Plateau, including: Soil-related valid observation data were extracted from the valid observation dataset of permafrost on the Tibetan Plateau, and the extracted valid observation data were processed by missing value imputation, outlier removal and standardization to obtain the standardized permafrost observation dataset of the Tibetan Plateau. Based on the soil characteristics of the Qinghai-Tibet Plateau, a soil texture classification standard for the Qinghai-Tibet Plateau region was formulated. The standardized permafrost observation dataset of the Qinghai-Tibet Plateau was classified using the aforementioned soil texture classification standard for the Qinghai-Tibet Plateau region. Soil samples in the permafrost region of the Qinghai-Tibet Plateau were divided into different texture categories, and the permafrost texture classification results of the Qinghai-Tibet Plateau were obtained. Based on the classification results of permafrost texture in the Qinghai-Tibet Plateau, soil texture types with the same characteristics are integrated and classified to obtain a set of permafrost soil texture types in the Qinghai-Tibet Plateau.

4. The method for calculating the liquid water content of permafrost on the Qinghai-Tibet Plateau according to claim 3, characterized in that, Soil texture classification standards for the Qinghai-Tibet Plateau region include: Particle size range, water content characteristics, and physical properties.

5. The method for calculating the liquid water content of permafrost on the Qinghai-Tibet Plateau according to claim 1, characterized in that, The process involves selecting corresponding temperature and moisture content samples from the effective observation dataset of permafrost on the Tibetan Plateau, based on the set of soil texture types, and constructing a quantitative relationship between solid moisture content and soil temperature according to the physical laws of permafrost hydrothermal processes. This includes: Based on the set of soil texture types on the Qinghai-Tibet Plateau, temperature and moisture content data corresponding to each soil texture type were selected from the effective observation dataset of permafrost on the Qinghai-Tibet Plateau, and temperature and moisture content samples for different soil texture types were obtained. Using the temperature and moisture content samples for different soil texture types, the content of solid water is calculated based on the physical laws of the hydrothermal process of frozen soil. Based on the content of solid water, thermophysical experimental data were used to obtain the relationship between solid water and temperature, and preliminary data on the relationship between solid water content and soil temperature were obtained. The preliminary data on the relationship between solid moisture content and soil temperature were statistically analyzed to construct a quantitative relationship between solid moisture content and soil temperature. The quantitative relationship between the solid moisture content and soil temperature is expressed as follows: ； in, This refers to the solid moisture content. This is a constant representing the initial solid water content; The energy conversion constant between solid water and temperature; This is a correction factor for the effect of temperature on the moisture content of solids; Soil temperature; This is the exponential coefficient of the effect of temperature on the amount of solid water.

6. The method for calculating the liquid water content of permafrost on the Qinghai-Tibet Plateau according to claim 1, characterized in that, The quantitative relationship is adjusted and fitted by preset physical conditions to obtain a family of solid moisture content and soil temperature relationships classified by texture, including: Set a preset set of physical conditions for different soil texture types, including: saturation, maximum frost depth and temperature range; The quantitative relationship and the preset set of physical conditions are fitted to obtain the initial parameters for adjustment and fitting; The initial parameters are nonlinearly adjusted using curve fitting techniques and combined with a preset set of physical conditions to obtain a family of relationships between solid moisture content and soil temperature.

7. The method for calculating the liquid water content of permafrost on the Qinghai-Tibet Plateau according to claim 1, characterized in that, Based on the aforementioned family of solid water content and soil temperature relationships categorized by texture, and considering the water storage characteristics and effective pore size characteristics of different soil textures that can participate in freezing, the total soil water content is distributed between solid and liquid water, determining a unified calculation relationship for the liquid water content of permafrost on the Qinghai-Tibet Plateau, including: For different soil texture types, the water storage characteristics and effective porosity characteristics that can participate in freezing are analyzed and determined, and the water storage and effective porosity characteristics data of soil texture are obtained. Based on the water storage capacity and effective porosity characteristics of the soil texture, the total water content of each soil texture type is calculated, and the total water content of each soil texture type is obtained. Based on the aforementioned family of relationships between solid water content and soil temperature categorized by texture, the total water content of each soil texture type is distributed between solid water and liquid water, yielding the calculation results of the solid water and liquid water distribution. Based on the calculation results of the solid water and liquid water distribution, a unified calculation relationship for the liquid water content of permafrost in the Qinghai-Tibet Plateau is derived. The expression for the unified calculation relationship of the liquid water content of the permafrost on the Qinghai-Tibet Plateau is as follows: ； in, This refers to the liquid water content. This is the maximum potential content constant of liquid water; The energy threshold for the transition of liquid water; A coefficient characterizing soil structure and its influence on liquid water distribution; Soil saturation; Soil temperature; This is the exponential coefficient representing the effect of temperature on the liquid water content.

8. The method for calculating the liquid water content of permafrost on the Qinghai-Tibet Plateau according to claim 7, characterized in that, The aforementioned combination of the solid water content and soil temperature relationship family classified by texture is used to distribute the total water content of each soil texture type between solid water and liquid water, obtaining the calculation results of the solid water and liquid water distribution, including: Based on the total water content of each soil texture type, the initial total water content of each soil texture is determined, wherein the initial total water content includes: solid water and liquid water; Based on the family of solid water content and soil temperature relationships classified by texture, the solid water content is extracted from the total water content of each soil texture type to obtain the estimated solid water content for each soil texture. The estimated solid water content of each soil texture is combined with the initial total water content of each soil texture to calculate the liquid water content of each soil texture. By summarizing the estimated solid water content and calculated liquid water content for each soil texture, the calculation results of the solid water and liquid water distribution are obtained.

9. The method for calculating the liquid water content of permafrost in the Qinghai-Tibet Plateau according to claim 1, characterized in that, The expression for the improved VIC model is: ； in, The rate of change of soil moisture; This refers to precipitation. Evaporation and dissipation Changes in soil moisture storage; The adjustment coefficient that affects the flow of liquid water; This refers to the liquid water content. This refers to the liquid water content of soil under saturated conditions. The permeability coefficient is temperature-dependent.

10. A system for calculating the liquid water content of permafrost in the Qinghai-Tibet Plateau, characterized in that, include: The dataset observation module is used to acquire soil observation data from multiple representative stations on the Qinghai-Tibet Plateau at different times and different soil depths, and to perform quality control and processing on the soil observation data to obtain an effective observation dataset of permafrost on the Qinghai-Tibet Plateau. The soil classification module is used to classify the soils in the permafrost region of the Qinghai-Tibet Plateau based on the effective observation dataset of permafrost in the Qinghai-Tibet Plateau, and obtain a set of soil texture types in the permafrost region of the Qinghai-Tibet Plateau. The temperature and moisture content sample selection module is used to select corresponding temperature and moisture content samples from the effective observation dataset of permafrost on the Tibetan Plateau based on the set of soil texture types of permafrost on the Tibetan Plateau, and to construct a quantitative relationship between solid moisture content and soil temperature based on the physical laws of permafrost hydrothermal processes. The relationship adjustment and fitting module is used to adjust and fit the quantitative relationship through preset physical conditions to obtain a family of solid moisture content and soil temperature relationships classified by texture. The liquid water content allocation module is used to allocate the total soil water content between solid water and liquid water based on the family of solid water content and soil temperature relationships classified by texture, combined with the water storage characteristics and effective pore characteristics that can participate in freezing of different soil textures, and to determine the unified calculation relationship of liquid water content of permafrost in the Qinghai-Tibet Plateau. The model improvement module is used to embed the unified calculation relationship of liquid water content of permafrost in the Qinghai-Tibet Plateau into the VIC model to obtain the improved VIC model. The liquid water content calculation module is used to calculate the distribution of liquid water content in the permafrost region of the Qinghai-Tibet Plateau using the VIC model.

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