A method, system, and application for runoff simulation based on a loosely coupled hydrological model of glacier and non-glacier zones.

Abstract

The application belongs to the technical field of regional hydrological numerical simulation, and particularly relates to a runoff simulation method, system and application of a loose coupling hydrological model based on glacier and non-glacier partitioning. The method firstly divides the glacier area and the non-glacier area based on the glacier inventory data and the snow cover product, performs grid processing by using a digital elevation model, then respectively uses a VIC model and a DETIM model to simulate the hydrological process of the non-glacier area and the glacier area, realizes differential modeling, and obtains the total runoff simulation process of the basin by fusing the results. The application solves the problems of poor model expansibility and high reuse difficulty in traditional integrated modeling through a loose coupling framework, improves the simulation accuracy and deployment efficiency, and is suitable for water resource assessment and climate response research in alpine mountainous areas.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of regional hydrological numerical simulation, and particularly relates to a runoff simulation method, system and application of a loose coupling hydrological model based on glacier and non-glacier partitioning. BACKGROUND

[0002] In alpine mountainous basins, the hydrological cycle is jointly driven by multiple sources of glacier meltwater, rainfall runoff, and snowmelt water. Accurate simulation of the runoff characteristics of different water sources in the basin is of great significance for water resource assessment and climate response research. Existing hydrological models have made significant progress in simulating snow processes, and usually adopt a unified modeling architecture to integrate the glacier module with the main model to ensure consistency and closure of the simulation process.

[0003] However, in mixed glacier-non-glacier basins, the traditional integrated modeling approach has two key technical limitations:

[0004] First, most mainstream models use a structural embedded integration approach, which requires modification of the main model structure when introducing the glacier module, resulting in a strong coupling architecture. While this approach helps to unify process description, it also poses problems such as poor model scalability and high reuse difficulty, especially lacking support for differential modeling of glacier and non-glacier regions and independent control of spatial resolution. The glacier region usually has complex terrain and is highly sensitive to microclimate changes, requiring a resolution of 30 meters to accurately depict glacier dynamics, snow changes, and energy budget. The non-glacier region, on the other hand, is dominated by rainfall runoff and soil infiltration, and can be modeled at a scale of several kilometers to tens of kilometers. The unified structure and resolution configuration under the unified structure cannot meet the different needs of modeling accuracy in the two regions, resulting in over-smoothing or distorted response of the glacier process, affecting the overall simulation effect.

[0005] Second, the glacier region and the non-glacier region differ significantly in runoff mechanism, meteorological driving response, and underlying surface parameter configuration, making it difficult for a unified structure model to flexibly respond to the modeling characteristics of different regions. Current model systems rely on manual division and cumbersome operation processes, lacking a clear structure, simple operation, and flexible configuration of loose coupling mechanism, making it difficult to achieve efficient integration and high-precision result fusion while ensuring consistency of driving data and coordination of parameters. In particular, in the face of regional rapid deployment, scenario simulation, or engineering evaluation, existing methods cannot balance modeling efficiency, flexible adaptation, and simulation accuracy.

[0006] Therefore, there is an urgent need for a glacier-non-glacier joint modeling method that supports spatial partitioning, flexible combination of model structures, independent configuration of resolution, unified driving input, and result fusion output, to improve the adaptability, deployment efficiency, and runoff simulation accuracy of the model in complex mountainous basins. SUMMARY

[0007] The application aims to provide a runoff simulation method, system and application of a loose coupling hydrological model based on glacial and non-glacial zoning, aiming to solve the problems of insufficient accuracy, difficulty in model reuse and poor parameter regulation flexibility in the hydrological simulation of a high-cold mountainous glacial-non-glacial mixed recharge basin.

[0008] The application achieves the above-mentioned purpose through the following technical solutions:

[0009] In a first aspect, the application provides a runoff simulation method of a loose coupling hydrological model based on glacial and non-glacial zoning, which comprises the following steps:

[0010] S1. Dividing a target basin with mixed recharge water sources into a glacial zone and a non-glacial zone;

[0011] S2. Grid processing the target basin based on a DEM (Digital Elevation Model) to divide it into multiple grid cells and use them as basic calculation units, and counting and outputting the area proportion of the glacial zone and the non-glacial zone in each calculation unit;

[0012] S3. Carrying out runoff process simulation of the target basin based on a distributed hydrological model; combining the area proportion of the non-glacial zone in each grid cell, using the surface runoff module of the model to calculate the daily runoff output of the non-glacial zone, and generating its runoff simulation sequence;

[0013] S4. Differentiating modeling of the glacial zone based on a distributed enhanced temperature index model, and outputting the daily runoff simulation result of the glacial zone;

[0014] S5. Fusing the runoff simulation sequence of the non-glacial zone and the daily runoff result of the glacial zone to obtain the total simulated runoff of the basin.

[0015] Further, in the grid processing of the target basin based on the DEM, the grid resolution is set in the range of 0.05-0.25°.

[0016] Further, step S3 comprises:

[0017] S301. Assigning a grid ID to the grid cell, recording the central point longitude and latitude coordinates thereof as the spatial index of the model input file;

[0018] S302. Configuring meteorological variables for the grid cell, including daily precipitation, maximum temperature, minimum temperature and wind speed;

[0019] S303. Configuring basic input parameters for the grid cell, including a soil parameter file, a vegetation parameter file and an elevation parameter file;

[0020] S304. Based on the measured runoff data at the watershed outlet, calibrate the model parameters, wherein the model parameters include: Infilt, Ds, Dsmax, Ws and the depth of the second and third soil layers, and the calibration objective is to maximize the Nash efficiency coefficient and minimize the relative deviation.

[0021] S305. Combining the parameter-calibrated distributed hydrological model with the runoff generation results of the gridded model and the area ratio of the non-glacial region, the daily runoff simulation sequence of the non-glacial region is calculated and generated, expressed as:

[0022] ;

[0023] Where Q1,j is the simulated runoff in the non-glacier area of ​​the target region on day j, f is the area ratio of the non-glacier area, and Q2,j is the total simulated runoff in the non-glacier area of ​​the target region on day j.

[0024] Furthermore, the basic input parameters include:

[0025] Soil parameter file, defining the thickness of each soil layer, initial water content, saturated hydraulic conductivity, water diffusion coefficient, and baseflow curve parameters;

[0026] The vegetation parameter file records the distribution ratio and root depth of various vegetation types, and calls the preset monthly-scale LAI, minimum stomatal resistance, albedo and roughness parameters in the vegetation library file.

[0027] The elevation parameter file subdivides each grid cell into multiple elevation zones, configuring the area ratio, average elevation, and precipitation percentage for each zone.

[0028] Furthermore, the calibration model parameters include the following steps:

[0029] Based on measured runoff, runoff simulation of the target watershed is performed using a distributed hydrological model to obtain the total simulated runoff sequence for the entire watershed.

[0030] By comparing the simulated total runoff with the measured runoff, the Nash efficiency coefficient and relative deviation are calculated and used as calibration indicators.

[0031] By adjusting the model parameters, the optimal combination of model parameters is obtained with the goal of maximizing the Nash efficiency coefficient and minimizing the relative bias.

[0032] Furthermore, step S4 includes:

[0033] S401. Divide the glacier region into a simulated grid at a set resolution;

[0034] S402. Based on DEM data, perform terrain correction and spatial interpolation on key meteorological elements on the simulation network to form input data consistent with the model resolution;

[0035] S403. Based on the input data, the traditional day-degree factor method or the temperature index method that incorporates clear-sky solar radiation is used to simulate the generation and runoff process of glacial meltwater. When the Nash efficiency coefficient and relative deviation between the measured runoff and the total simulated runoff are optimal, the glacier model parameters are optimal, and the corresponding calculated daily simulated runoff results for the glacier area are obtained.

[0036] Furthermore, in step S403, the traditional day-degree factor method is used to simulate the glacial meltwater generation and confluence process, expressed as:

[0037] ;

[0038] Where M is the rate of ice melting, in mm / h; DDF ice The day factor for ice, in mm / day / ℃, represents the amount of water melted per unit of positive temperature; T is the temperature, in ℃, which drives the melting process when the temperature is positive; n represents the time step.

[0039] The temperature index method based on clear-sky solar radiation is introduced to simulate the formation and runoff of glacial meltwater. The expression is:

[0040] ;

[0041] Wherein, MF is the basic melting factor, with the unit being mm / day / ℃, representing the amount of water melted per unit of positive temperature. is the ice radiation coefficient, used to characterize the enhancing effect of solar radiation on the melting process; I represents the potential solar radiation under clear sky conditions, in W / m². 2 .

[0042] Furthermore, step S5 includes:

[0043] Calculation of runoff in non-glacial areas based on runoff simulation sequences ;

[0044] According to glacier runoff Non-glacier runoff Determine the total simulated outflow Q; ;

[0045] Using the maximization of Nash efficiency coefficient and the minimization of relative deviation as optimization objectives, the hydrological parameters of the glacier area are optimized and adjusted, and the total outlet simulated runoff Q driven by the optimal parameter combination is output.

[0046] Secondly, this invention proposes a runoff simulation system based on a loosely coupled hydrological model of glacier and non-glacier zones, applied to perform the runoff simulation method described above. The system includes:

[0047] The zoning module is used to divide a target watershed with mixed water supply sources into glacial and non-glacial zones;

[0048] The gridding module is used to perform gridding on the target watershed based on the DEM, dividing it into multiple grid cells as basic calculation units, and statistically outputting the area ratio of glacier and non-glacier areas in each calculation unit.

[0049] The non-glacial area simulation module is used to simulate the runoff generation process of the target watershed based on a distributed hydrological model. Combining the area proportion of the non-glacial area in each grid cell, the daily runoff output of the non-glacial area is calculated using the surface runoff module of the model to generate its runoff simulation sequence.

[0050] The glacier simulation module is used to perform differentiated modeling of glacier areas based on a distributed enhanced temperature index model, and outputs daily runoff simulation results for glacier areas.

[0051] The fusion module is used to combine the simulated runoff sequence in non-glacial areas with the daily runoff results in glacial areas to obtain the total simulated runoff of the watershed.

[0052] Secondly, this invention proposes an application of the runoff simulation method based on a loosely coupled hydrological model of glacier and non-glacier zones, as described above. The method is applied to the runoff simulation of a typical glacier-non-glacier mixed-feed basin in high-altitude and cold mountainous areas.

[0053] The beneficial effects of this invention are as follows:

[0054] 1. This invention constructs a loosely coupled, differentially configured hydrological simulation framework, enabling independent operation and parameter partitioning of models in glacial and non-glacial regions. Compared to traditional integrated modeling methods, this invention effectively solves the problems of poor model scalability and high reusability, significantly improving the accuracy of hydrological simulations in mixed glacial-non-glacial watersheds in high-altitude mountainous areas. Particularly in glacial regions, this invention supports high-resolution simulations down to 30 meters, accurately depicting glacier dynamics, snow cover changes, and energy budgets, providing more precise data support for water resource assessment and climate response research.

[0055] 2. This invention achieves accuracy optimization in glacier runoff simulation under conditions without actual glacier flow measurements. By optimizing the Nash efficiency coefficient and minimizing relative deviation, this invention iteratively adjusts key hydrological parameters in glacier regions, making the simulation results more closely match actual observation data. Furthermore, the model structure of this invention is loosely coupled and flexibly configured, possessing good engineering application and regional adaptability, and can be widely applied to hydrological process modeling in different high-altitude and cold mountainous watersheds. Attached Figure Description

[0056] Figure 1A schematic flowchart of a runoff simulation method based on a loosely coupled hydrological model of glacier and non-glacier zones provided in this application embodiment;

[0057] Figure 2 Another flowchart illustrating the runoff simulation method based on a loosely coupled hydrological model of glacier and non-glacier zones provided in this application embodiment;

[0058] Figure 3 This is a schematic diagram of the VIC simulated flow process in the Yangbajing watershed in the specific implementation of this application.

[0059] Figure 4 This is a schematic diagram of the Yangbajing watershed outlet flow process obtained from VIC calculations based on two improved ice-melting models in the specific implementation of this application. Detailed Implementation

[0060] The present application will now be described in further detail with reference to the accompanying drawings. It should be noted that the following specific embodiments are only used to further illustrate the present application and should not be construed as limiting the scope of protection of the present application. Those skilled in the art can make some non-essential improvements and adjustments to the present application based on the above application content.

[0061] Currently, several key challenges exist in simulating mixed glacier-non-glacier watersheds: On the one hand, glacier models generally lack representation of the systemic physical mechanisms of hydrological processes in non-frozen areas (such as infiltration and evapotranspiration); on the other hand, non-glacier models have limited accuracy in dealing with small-area glacier runoff, making it difficult to accurately capture the spatial heterogeneity and nonlinear response characteristics of multi-source hydrological processes. Furthermore, existing large-scale distributed hydrological model systems that have integrated glacier modules still generally suffer from technical bottlenecks such as difficulties in model reuse, insufficient handling of differences in meteorological responses between glacier and non-glacier regions, and poor flexibility in parameter adjustment.

[0062] Example 1

[0063] To address the aforementioned issues, this application proposes a runoff simulation method based on a loosely coupled hydrological model of glacier and non-glacier zones. The basic concept of this application is to construct a loosely coupled, differentially configured hydrological simulation framework for typical glacier-non-glacier mixed recharge basins in high-altitude and cold mountainous areas. The cryosphere meltwater simulation model (DETIM) and the large-scale distributed hydrological model (VIC) are modularly integrated to simulate hydrological processes in glacier and non-glacier zones respectively. Through unified driving and result fusion, accurate, efficient, and scalable hydrological process modeling is achieved.

[0064] like Figures 1-2 As shown, the above method specifically includes the following steps:

[0065] S1. Glacier-Non-Glacier Region Division: Target watersheds with mixed water supply sources (such as typical glacier-non-glacier mixed water supply watersheds in high-altitude and cold mountainous areas) are divided into glacier regions and non-glacier regions.

[0066] In practice, based on the second national glacier inventory data (V1.0) and MODIS snow cover products, the watersheds in high-altitude mountainous areas are divided into glacier and non-glacier zones. The glacier zone division is based on the spatial distribution of the glacier inventory data, while the non-glacier zone includes bare soil, vegetation-covered areas, etc. This step is achieved through automated processing of remote sensing data to ensure the accuracy and efficiency of the zoning.

[0067] S2. Model Calculation and Mesh Generation: The target watershed is meshed based on the DEM to divide it into multiple mesh units as basic calculation units. The area ratio of glacier and non-glacier areas in each calculation unit is statistically analyzed and output.

[0068] In practice, the grid resolution can be flexibly set within the range of 0.05 to 0.25°, depending on the accuracy of the regional data, the simulation objectives, and the computational resource conditions, with a default of 0.1°. After the grid is generated, the area ratio of glacial and non-glacial regions in each grid cell is statistically analyzed to provide a spatial partitioning basis for subsequent differentiated model configuration and loosely coupled simulation.

[0069] The S3.VIC (Variable Infiltration Capacity) model simulates hydrological processes: Based on a distributed hydrological model (VIC) that can calculate water and energy balance, multi-layer soil structure, support the expression of heterogeneity of subgrid underlying surface and runoff generation mechanism, it simulates the runoff generation process of the target watershed; combined with the area ratio of non-glacial area in each grid cell, the daily runoff output of non-glacial area is calculated using the surface runoff module of the model to generate its runoff simulation sequence.

[0070] S4. Simulation of hydrological processes in glacier areas: Differentiated modeling of glacier areas is performed based on the Distributed Enhanced Temperature Index Model (DETIM), and the daily runoff simulation results of glacier areas are output.

[0071] S5. The simulation results of runoff in non-glacial areas and daily runoff results in glacial areas are fused to obtain the total simulated runoff of the watershed.

[0072] Alternatively, in the gridding of the target watershed based on the DEM, the grid resolution can be set in the range of 0.05 to 0.25°.

[0073] In one specific embodiment, step S3 includes:

[0074] S301. Assign a grid ID to the grid cell and record the latitude and longitude coordinates of its center point as a spatial index for the model input file.

[0075] S302. Configure meteorological variables for grid cells, including daily precipitation, maximum temperature, minimum temperature and wind speed; if data on elements such as radiation and atmospheric pressure are lacking, they can be estimated and supplemented through integrated climate preprocessing modules (such as MTCLIM).

[0076] S303. Configure basic input parameters for the grid cells, including soil parameter files, vegetation parameter files, and elevation parameter files.

[0077] S304. Based on measured runoff data at the watershed outlet, calibrate the model parameters. Model parameters include: Infilt (soil infiltration parameter), Ds (baseflow nonlinear release coefficient), Dsmax (maximum baseflow proportion), Ws (soil moisture nonlinear curve parameter), and the depths of the second and third soil layers (d2, d3). The VIC model typically uses a three-layer soil structure, with d2 and d3 representing the thickness of the middle and deep soil layers, respectively. The calibration objective is to maximize the Nash efficiency coefficient and minimize the relative bias. Specifically, the Nash-Sutcliffe Efficiency (NSE) and Relative Bias (RBIAS) are used as model performance evaluation indicators, and the optimal parameter combination is found through an optimization algorithm.

[0078] S305. Combining the parameter-calibrated distributed hydrological model with the runoff generation results of the gridded model and the area ratio of the non-glacial region, the daily runoff simulation sequence of the non-glacial region is calculated and generated, expressed as:

[0079] Q1,j=f·Q2,j

[0080] Where Q1,j is the simulated runoff in the non-glacier area of ​​the target region on day j, f is the area ratio of the non-glacier area, and Q2,j is the total simulated runoff in the non-glacier area of ​​the target region on day j.

[0081] In one specific embodiment, calibrating the model parameters includes the following steps:

[0082] Based on measured runoff, runoff simulation of the target watershed is performed using a distributed hydrological model to obtain the total simulated runoff sequence for the entire watershed.

[0083] The simulated total runoff was compared with the measured runoff, and the Nash efficiency coefficient and relative deviation were calculated and used as calibration indicators.

[0084] By adjusting the model parameters, the optimal combination of model parameters is obtained with the goal of maximizing the Nash efficiency coefficient and minimizing the relative bias.

[0085] In one specific embodiment, the basic input parameters include:

[0086] Soil parameter file, defining the thickness of each soil layer, initial moisture content, saturated hydraulic conductivity, water diffusion coefficient, and baseflow curve parameters.

[0087] The vegetation parameter file records the distribution ratio and root depth of various vegetation types, and calls the preset monthly-scale LAI, minimum stomatal resistance, albedo, and roughness parameters in the vegetation library file.

[0088] The elevation parameter file subdivides each grid cell into multiple elevation zones (e.g., 10), configuring the area ratio, average elevation, and precipitation percentage of each zone to express the moderating effect of topography on temperature and precipitation, thereby enhancing the accuracy of snow cover simulation.

[0089] In one specific embodiment, step S4 includes:

[0090] S401. Divide the glacier area into a simulated grid at a set resolution (e.g., 30m);

[0091] S402. Based on DEM data (a type of geospatial data that records surface elevation information in raster or vector form. DEM data is usually in raster format (such as GeoTIFF), where each cell represents the elevation value of a geographic unit. NASA, USGS, and other publicly available data sources can be downloaded online), and combined with the monthly temperature lapse rate and the spatial distribution characteristics of remotely sensed precipitation, topographic correction and spatial interpolation are performed on key meteorological elements such as temperature and precipitation. This converts the original meteorological data into high spatial accuracy input data consistent with the model's calculation resolution, improving the model's responsiveness to topographic changes and simulation accuracy.

[0092] S403. Based on the input data, the traditional day-degree factor method or the temperature index method that incorporates clear-sky solar radiation is used to simulate the generation and runoff process of glacial meltwater. When the Nash efficiency coefficient and relative deviation between the measured runoff and the total simulated runoff are optimal, the glacier model parameters are optimal, and the corresponding daily simulated runoff results of the glacier area are calculated.

[0093] In one specific embodiment, in step S403, the traditional day-degree factor method is used to simulate the glacial meltwater generation and confluence process, expressed as:

[0094] ;

[0095] Where M is the rate of ice melting, in mm / h; DDF ice The day factor for ice, expressed in mm / day / ℃, represents the amount of water melted per unit of positive temperature; T is the temperature, expressed in ℃, which drives the melting process when the temperature is positive; n represents the time step.

[0096] The temperature index method based on clear-sky solar radiation is introduced to simulate the formation and runoff of glacial meltwater. The expression is:

[0097] ;

[0098] Wherein, MF is the basic melting factor, with the unit being mm / day / ℃, representing the amount of water melted per unit of positive temperature. is the ice radiation coefficient, used to characterize the enhancing effect of solar radiation on the melting process; I represents the potential solar radiation under clear sky conditions, in W / m². 2 .

[0099] In one specific embodiment, step S5 includes:

[0100] Calculation of runoff in non-glacial areas based on runoff simulation sequences ;

[0101] According to glacier runoff Non-glacier runoff Determine the total simulated outflow Q; ;

[0102] Using the maximization of the Nash efficiency coefficient and the minimization of the relative deviation as optimization objectives, the hydrological parameters of the glacier region (the traditional day factor method is DDF) are optimized. ice The temperature index method considering clear-sky solar radiation is... The system iteratively adjusts the parameters and outputs the total simulated outflow Q driven by the optimal parameter combination.

[0103] In one specific embodiment, the present invention also proposes a runoff simulation system based on a loosely coupled hydrological model of glacier and non-glacier zones, applied to perform the runoff simulation method described above. The system includes:

[0104] The zoning module is used to divide a target watershed with mixed water supply sources into glacial and non-glacial zones;

[0105] The gridding module is used to perform gridding on the target watershed based on the DEM, dividing it into multiple grid cells as basic calculation units, and statistically outputting the area ratio of glacier and non-glacier areas in each calculation unit.

[0106] The non-glacial area simulation module is used to simulate the runoff generation process of the target watershed based on a distributed hydrological model. Combining the area proportion of the non-glacial area in each grid cell, the daily runoff output of the non-glacial area is calculated using the surface runoff module of the model to generate its runoff simulation sequence.

[0107] The glacier simulation module is used to perform differentiated modeling of glacier areas based on a distributed enhanced temperature index model, and outputs daily runoff simulation results for glacier areas.

[0108] The fusion module is used to combine the simulated runoff sequence in non-glacial areas with the daily runoff results in glacial areas to obtain the total simulated runoff of the watershed.

[0109] It should be noted that each module in the above runoff simulation system corresponds to steps S1 to S5 in implementing the above runoff simulation method. The instances and application scenarios implemented by multiple modules and their corresponding steps are the same, but are not limited to the content disclosed in the above embodiment 1.

[0110] According to the above embodiments, the runoff simulation system of the present invention, based on the differences in the physical mechanisms of hydrological processes between glacial and non-glacial regions, achieves independent modeling and result fusion of different zones through modular design. Its core principle lies in:

[0111] Differentiated modeling by region: In glacier areas, a high-resolution (30m) DETIM model is used to simulate snowmelt based on the temperature index method and capture the impact of micro-topography on energy balance; in non-glacier areas, a large-scale VIC model is used to characterize the rainfall-runoff response through multi-layer soil structure and vegetation parameters.

[0112] Loose coupling mechanism: The two models run independently, and data interaction is achieved only through unified meteorological driving and grid area weighting, avoiding the intrusive problems of traditional strongly coupled architectures. Meltwater runoff output from the glacier region is directly superimposed on the VIC simulation results of the non-glacier region, and the parameters are optimized through feedback of total runoff at the outlet section (such as DDF~ice~ or Infilt).

[0113] In one specific embodiment, the present invention also proposes an application of the runoff simulation method based on the loosely coupled hydrological model of glacier and non-glacier partitions as described above. The method is applied to the runoff simulation of typical glacier-non-glacier mixed recharge basins in high-altitude cold mountainous areas (these basins have both glacial meltwater and precipitation / snow accumulation runoff as recharge sources).

[0114] For example, typical glacier-non-glacier mixed recharge basins in high-altitude and cold mountainous areas include basins in the Qinghai-Tibet Plateau and the Alps where glaciers coexist with vegetation / bare soil.

[0115] To more clearly illustrate the present invention and its advantages, the loose coupling method provided by the present invention will be further explained below in conjunction with specific embodiments and related partial figures.

[0116] To verify the applicability of the runoff simulation method based on a loosely coupled hydrological model of glacier and non-glacier zones proposed in this invention, an empirical test was conducted in the Yangbajing watershed, a typical glacier-non-glacier mixed-feed basin in high-altitude cold regions. Existing studies have shown that when directly using the DETIM model to simulate areas with a high proportion of bare soil, the model is prone to overestimation of runoff in bare soil areas because it fails to explicitly consider non-cryospheric hydrological processes such as evaporation and infiltration. Furthermore, the model struggles to accurately characterize the actual hydrological response through parameter calibration, and there is significant uncertainty in determining the degree-day factor and radiation coefficient.

[0117] To obtain more reasonable simulation results, combined with Figure 3 As shown, the VIC model was run and its parameters were calibrated at a spatial resolution of 0.1°. The results show that although the VIC model has a strong ability to characterize surface and soil processes, it exhibits a significant underestimation of flow in the Yangbajing watershed. The NSE of its simulation results is only 0.63, and the relative bias (RBIAS) reaches -23.3%, failing to accurately reproduce the actual runoff process.

[0118] Furthermore, two temperature index models are introduced into the VIC framework: one is the classical degree-day factor method (Model 1), and the other is an improved temperature index method considering potential clear-sky direct solar radiation (Model 2). Combined with... Figure 4 As shown, the simulation results indicate that both coupled models significantly improve the underestimation problem of the VIC model, with the relative biases decreasing to -8.1% and -8.2%, respectively, and the NSE values ​​increasing from 0.63 to 0.84, which are significantly better than the simulation performance of the original VIC and the standalone DETIM models.

[0119] According to the above embodiments, this invention effectively solves the problems of insufficient accuracy and model reuse in hydrological simulation of mixed glacier-non-glacier recharge watersheds in high-altitude cold mountainous areas by spatial partitioning, flexible combination of model structures, and independent resolution configuration. The method first divides the watershed into glacier and non-glacier zones and performs gridding based on DEM data; then, it uses the VIC model and the DETIM model to simulate hydrological processes in the non-glacier and glacier zones respectively, achieving differentiated modeling; finally, it obtains the total watershed runoff by fusing the results. In empirical tests in the Yangbajing watershed, this method significantly improved simulation accuracy, verifying its feasibility and applicability. This invention not only provides a powerful tool for water resource assessment and climate response research in high-altitude cold mountainous areas but also has broad potential for engineering application and regional adaptation.

[0120] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of the present invention are generated.

[0121] The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions may be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions may be transmitted from one website, computer, server, or data center to another via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium may be any available medium that a computer can access, or a data storage device such as a server or data center that integrates one or more available media. The available medium may be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., a solid-state drive (SSD)).

[0122] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0123] In addition, the functional modules in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0124] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions 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 this application.

Claims

1. A method for runoff simulation based on a loosely coupled hydrological model of glacial and non-glacial partitioning, characterized in that, The method comprises the following steps: S1. Dividing a target basin with mixed recharge water sources into a glacier area and a non-glacier area; S2. Grid processing the target basin based on DEM to divide into a plurality of grid cells and as a basic calculation unit, and counting and outputting the area proportion of the glacier area and the non-glacier area in each calculation unit; S3. Carrying out runoff process simulation on the target basin based on a distributed hydrological model; combining the area proportion of the non-glacier area in each grid cell, using the surface runoff module of the model to calculate the daily runoff output of the non-glacier area, and generating a runoff simulation sequence thereof; Step S3 comprises: S301. Assigning a grid ID to the grid cell, recording the central point longitude and latitude coordinates thereof as a spatial index of a model input file; S302. Configuring meteorological variables for the grid cell, including daily precipitation, maximum air temperature, minimum air temperature and wind speed; S303. Configuring basic input parameters for the grid cell, including a soil parameter file, a vegetation parameter file and an elevation parameter file; S304. Taking the measured runoff data at the outlet of the basin as a benchmark to calibrate model parameters, wherein the model parameters include Infilt, Ds, Dsmax, Ws and the soil depths of the 2nd and 3rd layers, and the calibration targets are to maximize the Nash efficiency coefficient and minimize the relative deviation; S305. Combining the distributed hydrological model after parameter calibration, combining the grid model runoff results and the area proportion of the non-glacier area, and calculating and generating a daily runoff simulation sequence of the non-glacier area, the expression being: ； Wherein Q1,j is the simulation runoff of the non-glacier area of the target region on the jth day, f is the area proportion of the non-glacier area, and Q2,j is the simulation total runoff of the non-glacier area of the target region on the jth day; S4. Carrying out differential modeling on the glacier area based on a distributed enhanced temperature index model, and outputting a daily runoff simulation result of the glacier area; Step S4 comprises: S401. Dividing the glacier area into a simulation grid at a set resolution; S402. Based on DEM data, performing terrain correction and spatial interpolation on key meteorological elements on the simulation network to form input data consistent with the model resolution; S403. Combining the input data, using the degree-day factor method or the temperature index method with introduction of clear sky solar radiation to simulate glacier meltwater generation and confluence process, when the Nash efficiency coefficient and the relative deviation between the measured runoff and the total simulation runoff are optimal, the glacier model parameters at this time are optimal, and the corresponding calculated daily simulation runoff result of the glacier area is obtained; S5. Fusing the runoff simulation sequence of the non-glacier area and the daily runoff result of the glacier area to obtain the total simulation runoff of the basin.

2. The method according to claim 1, wherein, In the grid resolution setting range of the grid processing of the target basin based on DEM, the grid resolution is 0.05-0.25°.

3. The method according to claim 1, wherein, The basic input parameters comprise: A soil parameter file defining the thickness, initial water content, saturated hydraulic conductivity, water diffusion coefficient and base flow curve parameter of each layer of soil; A vegetation parameter file recording the distribution proportion and root depth of each type of vegetation, and calling the preset monthly scale LAI, minimum stomatal resistance, albedo and roughness parameters in the vegetation library file; An elevation parameter file, which subdivides each grid cell into multiple elevation zones, respectively configures the area proportion, average elevation and precipitation proportion of each zone.

4. The method according to claim 1, wherein, The rating model parameter includes the following steps: Based on the measured runoff, a distributed hydrological model is used to simulate the runoff of the target basin to obtain the total simulated runoff sequence of the whole basin; The simulated total runoff and the measured runoff are compared to calculate the Nash efficiency coefficient and the relative deviation, which are used as the rating index; The best model parameter combination is obtained by adjusting the model parameters to maximize the Nash efficiency coefficient and minimize the relative deviation.

5. The method according to claim 1, wherein, In step S403, the degree-day factor method is used to simulate the glacier meltwater generation and confluence process, and the expression is: ； where M is the meltwater rate of ice in mm / h; denotes the degree-day factor of ice in denotes the meltwater quantity per unit of positive air temperature; T is the air temperature in °C, driving the melting process when the temperature is positive; n denotes the time step; The temperature index method of clear sky solar radiation is introduced to simulate the glacier meltwater generation and confluence process, and the expression is: ； wherein, is the base melt factor in mm / day / °C, representing the amount of melt water per unit of positive air temperature conditions; is the ice albedo, used to characterize the enhancing effect of solar radiation on the melting process; represents the potential solar radiation under clear sky conditions in W / m².

6. The method according to claim 5, wherein, Step S5 includes: Calculating non-glacierized area runoff based on a sequence of non-glacierized area runoff simulations ; According to glacier runoff Non-glacier runoff Determine the total outlet simulated runoff ; The hydrological parameters of the glacier area are optimized and adjusted to maximize the Nash efficiency coefficient and minimize the relative deviation as the optimization target, and the total outlet simulated runoff Q under the optimal parameter combination is output.

7. A runoff simulation system based on a loosely coupled hydrological model of glacial and non-glacial partitioning, for performing the runoff simulation method of any one of claims 1-6, characterized in that, The system includes: A partition division module is configured to divide the target basin with mixed recharge water sources into a glacier area and a non-glacier area; A gridding processing module is configured to perform gridding processing on the target basin based on DEM to divide the target basin into multiple grid cells as basic calculation units, and to count and output the area proportion of the glacier area and the non-glacier area in each calculation unit; A non-glacier area simulation module is configured to simulate the runoff process of the target basin based on a distributed hydrological model; combined with the area proportion of the non-glacier area in each grid cell, the daily runoff output of the non-glacier area is calculated by using the surface runoff module of the model to generate the runoff simulation sequence of the non-glacier area; A glacier area simulation module is configured to model the glacier area based on a distributed enhanced temperature index model to output the daily runoff simulation result of the glacier area; A fusion module is configured to fuse the runoff simulation sequence of the non-glacier area and the daily runoff result of the glacier area to obtain the total simulated runoff of the basin.

8. Use of a runoff simulation method based on a loosely coupled hydrological model of glacial and non-glacial zoning according to any one of claims 1 to 6, characterized in that, The method is applied to the runoff simulation of a typical glacier-non-glacier mixed recharge basin in an alpine mountainous area.

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