Hydrological model loose coupling method based on glacier and non-glacier partitions and application thereof

Abstract

The invention 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 zones.The method comprises the steps that firstly, a glacier area and a non-glacier area are divided based on glacier cataloguing data and accumulated snow covering products, gridding processing is carried out through a digital elevation model, and a runoff simulation result is obtained; and performing hydrological process simulation on the non-glacier area and the glacier area by adopting a VIC model and a DETIM model respectively to realize differential modeling, and obtaining a basin total runoff simulation process through result fusion. Through the loose coupling framework, the problems of poor model expansibility and high reuse difficulty in traditional integrated modeling are solved, the simulation precision and deployment efficiency are improved, and the method is suitable for water resource evaluation and climate response research in the cold and cold mountainous area.

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 loosely coupled 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: 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 is mainly dominated by rainfall runoff and soil infiltration, which 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.

[0004] 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 a loosely coupled 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.

[0005] 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

[0006] The purpose of the present invention is to provide a runoff simulation method, system and application based on a loosely coupled hydrological model of glacier and non-glacier partitions, aiming to solve the problems of insufficient accuracy, difficulty in model reuse and poor flexibility in parameter control in hydrological simulation of glacier-non-glacier mixed supply basins in high-altitude mountainous areas.

[0007] The present invention achieves the above-mentioned purpose through the following technical solutions: In a first aspect, the present invention proposes a runoff simulation method based on a loosely coupled hydrological model of glacier and non-glacier partitions, the method comprising the following steps: S1. Divide the target watershed with mixed recharge sources into glaciated and non-glaciated areas; S2. Grid the target watershed based on a DEM (Digital Elevation Model) to divide it into multiple grid cells, which serve as basic calculation units. Count and output the area ratio of glaciated to non-glaciated areas in each calculation unit. S3. Simulate runoff generation in the target watershed using a distributed hydrological model. Considering the proportion of non-glaciated areas in each grid cell, use the model's surface runoff module to calculate daily runoff output in the non-glaciated areas and generate a simulated runoff sequence. S4. Conduct differentiated modeling of the glacier area based on the distributed enhanced temperature index model and output daily runoff simulation results for the glacier area; S5. Combine the runoff simulation series in the non-glaciated area and the daily runoff results in the glaciated area to obtain the total simulated runoff of the basin.

[0008] Furthermore, in the gridding process of the target watershed based on the DEM, the grid resolution is set in the range of 0.05 to 0.25°.

[0009] Furthermore, step S3 includes: S301. Assign a grid ID to the grid cell and record the longitude and latitude coordinates of its center point as a spatial index of the model input file; S302. Configure meteorological variables for the grid cell, including daily precipitation, maximum temperature, minimum temperature and wind speed; S303. Configure basic input parameters for the grid unit, including soil parameter files, vegetation parameter files, and elevation parameter files; S304. Calibrate model parameters based on measured runoff data at the watershed outlet. The model parameters include: Infilt, Ds, Dsmax, Ws, and the depths of the second and third soil layers. The calibration objectives are to maximize the Nash efficiency coefficient and minimize the relative deviation. S305. Combine the distributed hydrological model after parameter calibration and the runoff results of the grid model with the area ratio of the non-glaciated area to calculate and generate the daily runoff simulation sequence for the non-glaciated area. The expression is: Q1,j=f·Q2,j Where Q1,j is the simulated runoff of the non-glaciated area in the target area on the jth day, f is the area ratio of the non-glaciated area, and Q2,j is the total simulated runoff of the non-glaciated area in the target area model on the jth day.

[0010] Furthermore, the basic input parameters include: Soil parameter file, which defines the thickness of each soil layer, initial moisture content, saturated hydraulic conductivity, water diffusion coefficient, and base flow curve parameters; Vegetation parameter files record the distribution ratio and root depth of various types of vegetation, and call the monthly scale LAI, minimum stomatal resistance, albedo and roughness parameters preset in the vegetation library file; The elevation parameter file subdivides each grid cell into multiple elevation bands, and configures the area ratio, average elevation, and precipitation ratio of each band.

[0011] Furthermore, the step of calibrating the model parameters includes the following steps: Based on the measured runoff, the runoff of the target basin is simulated based on the distributed hydrological model to obtain the total simulated runoff sequence of the entire basin; Compare the simulated total runoff with the measured runoff, calculate the Nash efficiency coefficient and relative deviation and use them as calibration indicators; By adjusting the model parameters, the optimal model parameter combination is obtained with the goal of maximizing the Nash efficiency coefficient and minimizing the relative deviation.

[0012] Furthermore, step S4 includes: S401. Dividing the glacier area into simulation grids at a set resolution; S402. Based on the DEM data, terrain correction and spatial interpolation are performed on key meteorological elements on the simulation network to form input data consistent with the model resolution; S403. In combination with the input data, the traditional degree-day factor method or the temperature index method that introduces clear-sky solar radiation is used to simulate the glacier meltwater generation and confluence process. When the Nash efficiency coefficient and relative deviation between the measured runoff and the total simulated runoff are optimal, the glacier model parameters at this time are optimal, corresponding to the calculated daily simulated runoff results for the glacier area. Furthermore, in step S403, the traditional degree-day factor method is used to simulate the glacier meltwater generation and confluence process, and the expression is: M Where M is the melting rate of ice, in mm / h; DDF ice The degree-day factor of ice, in units of mm / day / °C, represents the amount of meltwater caused by each unit of positive air temperature; T is the air temperature, in °C, which drives the melting process when the temperature is positive; n represents the time step; The temperature index method of clear sky solar radiation is introduced to simulate the generation and confluence of glacier meltwater. The expression is: M in, MF is the basic melt factor, with the unit of mm / day / ℃, which represents the amount of meltwater per unit positive temperature condition; is the ice radiation coefficient, which is used to characterize the enhancement effect of solar radiation on the melting process; I Indicates the potential solar radiation under clear sky conditions in W / m².

[0013] Furthermore, step S5 includes: Calculation of runoff in non-glaciated areas based on runoff simulation series in non-glaciated areas ; According to the runoff volume of glacier area and non-glaciated area runoff Determine the total outlet simulated runoff Q; ; Taking the maximization of Nash efficiency coefficient and the minimization of relative deviation as the optimization objectives, the hydrological parameters in the glacier area are optimized and adjusted, and the total outlet simulated runoff Q driven by the optimal parameter combination is output.

[0014] In a second aspect, the present invention proposes a runoff simulation system based on a loosely coupled hydrological model of glacier and non-glacier partitions, which is applied to perform the above-mentioned runoff simulation method, and the system includes: A zoning module is used to divide the target watershed with mixed recharge sources into glaciated and non-glaciated areas; The grid processing module is used to perform grid processing on the target watershed based on the DEM, so as to divide it into multiple grid cells as basic calculation units, and to count and output the area ratio of glacier area to non-glacier area in each calculation unit; The non-glaciated area simulation module is used to simulate the runoff generation process of the target basin based on the distributed hydrological model. Based on the area ratio of the non-glaciated area in each grid cell, the surface runoff module of the model is used to calculate the daily runoff output of the non-glaciated area and generate its runoff simulation sequence. The glacier simulation module is used to perform differentiated modeling of the glacier area based on the distributed enhanced temperature index model and output daily runoff simulation results of the glacier area; Combined with the fusion module, it is used to fuse the runoff simulation series in the non-glaciated area and the daily runoff results in the glaciated area to obtain the total simulated runoff in the basin.

[0015] In the second aspect, the present invention proposes an application of a runoff simulation method based on a loosely coupled hydrological model of glacier and non-glacier partitions as described above, which is applied to runoff simulation in typical glacier-non-glacier mixed recharge basins in high-altitude mountainous areas.

[0016] The beneficial effects of the present invention are: 1. This invention achieves the independent operation and parameter partitioning configuration of models in glacier and non-glacier areas by constructing a loosely coupled and differentially configured hydrological simulation framework. Compared with traditional integrated modeling methods, this invention effectively solves the problems of poor model scalability and high difficulty in reuse, and significantly improves the accuracy of hydrological simulation of glacier-non-glacier mixed recharge basins in high-altitude mountainous areas. Especially in glacier areas, this invention supports 30-meter high-resolution simulation, which can accurately depict glacier dynamics, snow cover changes, and energy budget, providing more accurate data support for water resource assessment and climate response research.

[0017] 2. This invention achieves precision optimization for glacier runoff simulation without actual glacier flow measurements. By optimizing the Nash efficiency coefficient and minimizing relative deviation, the present invention iteratively adjusts key hydrological parameters in glacier areas, ensuring simulation results are more consistent with actual observed data. Furthermore, the model's loosely coupled structure and flexible configuration offer excellent engineering scalability and regional adaptability, making it widely applicable to modeling hydrological processes in diverse alpine mountainous watersheds. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic flow chart of a runoff simulation method based on a loosely coupled hydrological model of glacier and non-glacier partitions provided in an embodiment of the present application; Figure 2 Another flow chart of a runoff simulation method based on a loosely coupled hydrological model of glacier and non-glacier partitions provided in an embodiment of the present application; Figure 3 This is a schematic diagram of the VIC simulated flow process in the Yangbajing Basin in the case part of the specific implementation method of this application; Figure 4 This is a schematic diagram of the outlet flow process of the Yangbajing Basin obtained by VIC calculation based on two improved ice melting models in the case part of the specific implementation method of this application. DETAILED DESCRIPTION

[0019] The present application is described in further detail below in conjunction with the accompanying drawings. It is necessary to point out that the following specific implementation methods are only used to further illustrate the present application and cannot be understood as limiting the scope of protection of the present application. Technicians in this field can make some non-essential improvements and adjustments to the present application based on the above application content.

[0020] Currently, the simulation of mixed glacier-non-glacier recharge basins faces several key challenges. Glacier models generally lack the systematic physical representation of hydrological processes (such as infiltration and evapotranspiration) in non-glacier areas. Furthermore, non-glacier models have limited accuracy for small-scale 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 with integrated glacier modules still face technical bottlenecks such as difficulty in model reuse, inadequate handling of differences in meteorological responses between glacier and non-glacier areas, and limited parameter control flexibility.

[0021] Example 1 In response to the above problems, this application proposes a runoff simulation method based on a loosely coupled hydrological model of glacier and non-glacier partitions. The basic concept of this application is to construct a loosely coupled and differentially configured hydrological simulation framework for typical glacier-non-glacier mixed recharge basins in high-altitude mountainous areas, and modularly integrate the cryosphere meltwater simulation model (DETIM) and the large-scale distributed hydrological model (VIC) to simulate the hydrological processes in glacier areas and non-glacier areas respectively. Through unified drive and result fusion, accurate, efficient and scalable hydrological process modeling is achieved.

[0022] like Figure 1-2 As shown, the above method specifically includes the following steps: S1. Glacier-non-glacier area division: Divide the target basin with mixed recharge water sources (such as the typical glacier-non-glacier mixed recharge basin in high-altitude mountainous areas) into glacier area and non-glacier area.

[0023] In specific implementation, basins in alpine mountainous areas were divided into glaciated and non-glaciated areas based on the Second China Glacier Inventory (V1.0) and the MODIS snow cover product. Glacier areas were classified based on the spatial distribution of glacier inventory data, while non-glaciated areas included bare soil and vegetation-covered areas. This step was automated through remote sensing data processing to ensure accurate and efficient zoning.

[0024] S2. Model calculation and grid division: Grid the target watershed based on the DEM to divide it into multiple grid cells as basic calculation units. Count and output the area ratio of glaciated area to non-glaciated area in each calculation unit.

[0025] In a specific implementation, the grid resolution can be flexibly set in the range of 0.05-0.25° according to the regional data accuracy, simulation target, and computing resource conditions, and the default is 0.1°. After completing the grid division, the area proportion of the glacier area and the non-glacier area in each grid unit is counted, providing a spatial partition basis for subsequent differentiated model configuration and loose coupling simulation.

[0026] S3. VIC (Variable Infiltration Capacity) model for hydrological process simulation: based on the distributed hydrological model (VIC) with water and energy balance calculation, multi-layer soil structure, supporting sub-grid underlying surface heterogeneity expression, and runoff generation mechanism, the runoff process simulation of the target basin is carried out; combined with the area proportion of the non-glacier area in each grid unit, the daily runoff output of the non-glacier area is calculated using the surface runoff module of the model, and the runoff simulation sequence is generated.

[0027] S4. Glacier area hydrological process simulation: based on the distributed enhanced temperature index model (DETIM), the glacier area is modeled differently, and the daily runoff simulation results of the glacier area are output.

[0028] S5. The runoff simulation sequence of the non-glacier area and the daily runoff results of the glacier area are fused to obtain the total simulation runoff of the basin.

[0029] Further optionally, in the grid processing of the target basin based on the DEM, the setting range of the grid resolution is 0.05-0.25°.

[0030] In a specific embodiment, step S3 includes: S301. Assign a grid ID to the grid unit, record the central point longitude and latitude coordinates as the spatial index of the model input file.

[0031] S302. Configure meteorological variables for the grid unit, including daily precipitation, maximum temperature, minimum temperature, and wind speed; if the data of radiation, atmospheric pressure, and other elements are lacking, they can be estimated and completed by the integrated climate preprocessing module (such as MTCLIM).

[0032] S303. Configure basic input parameters for the grid unit, including soil parameter files, vegetation parameter files, and elevation parameter files.

[0033] S304. Model parameters are calibrated based on measured runoff data at the watershed outlet. These parameters include: Infilt (soil infiltration parameter), Ds (baseflow nonlinear release coefficient), Dsmax (maximum baseflow fraction), Ws (soil moisture nonlinear curve parameter), and the depths of the second and third soil layers (d2 and d3). The VIC model typically uses a three-layer soil structure, with d2 and d3 representing the thicknesses of the middle and deep soil layers, respectively. The calibration objectives are 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 metrics. An optimization algorithm is used to identify the optimal parameter combination.

[0034] S305. Combine the distributed hydrological model after parameter calibration and the runoff results of the grid model with the area ratio of the non-glaciated area to calculate and generate the daily runoff simulation sequence for the non-glaciated area. The expression is: Q1,j=f·Q2,j Where Q1,j is the simulated runoff of the non-glaciated area in the target area on the jth day, f is the area ratio of the non-glaciated area, and Q2,j is the total simulated runoff of the non-glaciated area in the target area model on the jth day.

[0035] In one embodiment, calibrating the model parameters includes the following steps: Based on the measured runoff, the runoff of the target basin was simulated based on the distributed hydrological model to obtain the total simulated runoff sequence of the entire basin.

[0036] The simulated total runoff is compared with the measured runoff, and the Nash efficiency coefficient and relative deviation are calculated and used as calibration indicators.

[0037] By adjusting the model parameters, the optimal model parameter combination is obtained with the goal of maximizing the Nash efficiency coefficient and minimizing the relative deviation.

[0038] In a specific embodiment, the basic input parameters include: Soil parameter file, which defines the thickness of each soil layer, initial moisture content, saturated hydraulic conductivity, water diffusion coefficient, and base flow curve parameters.

[0039] Vegetation parameter files record the distribution ratio and root depth of various types of vegetation, and call the monthly scale LAI, minimum stomatal resistance, albedo and roughness parameters preset in the vegetation library file.

[0040] The elevation parameter file subdivides each grid cell into multiple elevation bands (e.g., 10), and configures the area ratio, average elevation, and precipitation ratio of each band. This is used to express the regulatory effect of terrain on temperature and precipitation, and enhance the accuracy of snow simulation.

[0041] In a specific embodiment, step S4 includes: S401. Divide the glacier area into simulation grids at a set resolution (e.g., 30 m); S402. Based on DEM data (geospatial data that records surface elevation information in raster or vector form. DEM data is typically in raster format (e.g., GeoTIFF), with each pixel representing the elevation of a geographic unit. Public data sources such as NASA and USGS are available for download online), terrain correction and spatial interpolation are performed on key meteorological elements such as temperature and precipitation, combined with the monthly temperature lapse rate and the spatial distribution characteristics of remotely sensed precipitation. This converts the raw meteorological data into high-spatial-precision input data consistent with the model's computational resolution, improving the model's responsiveness to terrain changes and simulation accuracy. S403. Combined with the input data, the traditional degree-day factor method or the temperature index method that introduces clear-sky solar radiation is used to simulate the generation and confluence of glacier 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, corresponding to the calculated daily simulated runoff results for the glacier area.

[0042] In a specific embodiment, in step S403, the traditional degree-day factor method is used to simulate the glacier meltwater generation and confluence process, and the expression is: M Where M is the melting rate of ice, in mm / h; DDF ice The degree-day factor of ice is expressed in mm / day / °C, which indicates the amount of meltwater caused by each unit of positive air temperature; T is the air temperature, in °C, which drives the melting process when the temperature is positive; n represents the time step; The temperature index method of clear sky solar radiation is introduced to simulate the generation and confluence of glacier meltwater. The expression is: M in, MF is the basic melt factor, with the unit of mm / day / ℃, which represents the amount of meltwater per unit positive temperature condition; is the ice radiation coefficient, which is used to characterize the enhancement effect of solar radiation on the melting process; I Indicates the potential solar radiation under clear sky conditions in W / m².

[0043] In a specific embodiment, step S5 includes: Calculation of runoff in non-glaciated areas based on runoff simulation series in non-glaciated areas ; According to the runoff volume of glacier area and non-glaciated area runoff Determine the total outlet simulated runoff Q; ; The optimization objectives are to maximize the Nash efficiency coefficient and minimize the relative deviation. The hydrological parameters of the glacier area (the traditional degree-day factor method is DDF ice ; The temperature index method considering clear sky solar radiation is ) is iteratively adjusted and the total outlet simulated runoff Q driven by the optimal parameter combination is output.

[0044] In a specific embodiment, the present invention further proposes a runoff simulation system based on a loosely coupled hydrological model of glacier and non-glacier partitions, which is applied to perform the above-mentioned runoff simulation method. The system includes: A zoning module is used to divide the target watershed with mixed recharge sources into glaciated and non-glaciated areas; The grid processing module is used to perform grid processing on the target watershed based on the DEM, so as to divide it into multiple grid cells as basic calculation units, and to count and output the area ratio of glacier area to non-glacier area in each calculation unit; The non-glaciated area simulation module is used to simulate the runoff generation process of the target basin based on the distributed hydrological model. Based on the area ratio of the non-glaciated area in each grid cell, the surface runoff module of the model is used to calculate the daily runoff output of the non-glaciated area and generate its runoff simulation sequence. The glacier simulation module is used to perform differentiated modeling of the glacier area based on the distributed enhanced temperature index model and output daily runoff simulation results of the glacier area; Combined with the fusion module, it is used to fuse the runoff simulation series in the non-glaciated area and the daily runoff results in the glaciated area to obtain the total simulated runoff in the basin.

[0045] It should be noted here that each module in the above-mentioned runoff simulation system corresponds to steps S1 to S5 in implementing the above-mentioned runoff simulation method, and the instances and application scenarios implemented by multiple modules and corresponding steps are the same, but are not limited to the contents disclosed in the above-mentioned embodiment 1.

[0046] According to the above embodiment, the runoff simulation system of the present invention is based on the physical mechanism differences of hydrological processes in glacial and non-glacial areas, and realizes independent modeling and result fusion of different regions through modular design. Its core principle is: Differentiated modeling by region: The high-resolution (30m) DETIM model is used in the glacier area to simulate snowmelt water based on the temperature index method to capture the impact of microtopography on energy budget; the large-scale VIC model is used in the non-glacier area to characterize the rainfall-runoff response through multi-layer soil structure and vegetation parameters.

[0047] Loosely coupled: The two models operate independently, interacting only through a unified meteorological driver and grid area weighting, avoiding the intrusiveness of traditional strongly coupled architectures. Meltwater runoff output from glaciers is directly added to the VIC simulation results for unglaciated areas, with optimization parameters (e.g., DDF or Infilt) fed back through the total runoff at the outlet section.

[0048] In a specific embodiment, the present invention also proposes an application of a runoff simulation method based on a loosely coupled hydrological model of glacier and non-glacier partitions as described above. The method is applied to runoff simulation in a typical glacier-non-glacier mixed recharge basin in a high-altitude mountainous area (this type of basin has both glacier meltwater and rainfall / snowfall runoff as two recharge sources).

[0049] For example, typical glacier-non-glacier mixed recharge basins in alpine mountainous areas include basins such as the Qinghai-Tibet Plateau and the Alps where glaciers and vegetation / bare soil coexist.

[0050] In order 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 implementation examples and some related figures.

[0051] To validate the applicability of the proposed runoff simulation method based on a loosely coupled hydrological model for glacier-non-glacier partitioning, an empirical test was conducted in the Yangbajing Basin, a typical glacier-non-glacier mixed recharge basin in alpine mountainous areas. Previous studies have shown that directly simulating areas with a high proportion of bare soil using the DETIM model can easily overestimate runoff in bare soil areas due to its failure to explicitly account for non-cryospheric hydrological processes such as evaporation and infiltration. This makes it difficult to accurately characterize the actual hydrological response through model parameter calibration, and there is significant uncertainty in the determination of degree-day factors and radiation coefficients.

[0052] In order to obtain more reasonable simulation results, Figure 3 As shown in the figure, the VIC model was run at a spatial resolution of 0.1° and its parameters were calibrated. The results show that although the VIC model has a strong ability to depict surface and soil processes, it significantly underestimates the flow in the Yangbajing watershed. The NSE of its simulation results is only 0.63, and the relative bias (RBIAS) is -23.3%, which also fails to accurately reproduce the measured runoff process.

[0053] Furthermore, two temperature index models are introduced into the VIC framework: one is the classic degree-day factor method (Model 1), and the other is an improved temperature index method that considers potential clear sky direct solar radiation (Model 2). Figure 4 As shown in the figure, the simulation results show that both coupled models significantly improved the underestimation problem of the VIC model, with the relative deviations reduced to -8.1% and -8.2% respectively, and the NSE values ​​also increased from 0.63 to 0.84, which are significantly better than the simulation performance of the original VIC and the single DETIM model.

[0054] According to the above embodiments, the present invention effectively solves the problems of insufficient accuracy and model reuse in hydrological simulation of glacier-non-glacier mixed recharge basins in high-altitude mountainous areas through spatial partitioning, flexible combination of model structures and independent configuration of resolution. The method first divides the basin into glacier areas and non-glacier areas, and performs grid processing based on DEM data; then, the VIC model and DETIM model are used to simulate the hydrological processes in non-glacier areas and glacier areas respectively to achieve differentiated modeling; finally, the total runoff of the basin is obtained by fusion of the results. In the empirical test of the Yangbajing Basin, this method significantly improved the simulation accuracy, verifying its feasibility and applicability. The present invention not only provides a powerful tool for water resource assessment and climate response research in high-altitude mountainous areas, but also has broad potential for engineering promotion and regional adaptation.

[0055] In the above embodiments, all or part of the embodiments may be implemented using software, hardware, firmware, or any combination thereof. When implemented using software, all or part of the embodiments may be implemented in the form of 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, the processes or functions described in the embodiments of the present invention are generated in whole or in part.

[0056] 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 computer-readable storage medium. For example, the computer instructions may be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via a wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) method. 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 includes one or more available media integrated therein. The available medium may be a magnetic medium (e.g., a floppy disk, a hard disk, a magnetic tape), an optical medium (e.g., a DVD), or a semiconductor medium (e.g., a solid-state drive (SSD)).

[0057] Those skilled in the art can understand that the units and algorithm steps of each example described in combination with the embodiments disclosed herein can be realized by electronic hardware or a combination of computer software and electronic hardware. Whether the functions are realized in hardware or software manner depends on the specific application and design constraints of the technical solutions. The skilled person can use different methods to realize the described functions for each specific application, but such implementation should not be considered beyond the scope of the present application.

[0058] In addition, each functional module in each embodiment of the present application can be integrated in one processing unit, or each unit can exist physically independently, or two or more units can be integrated in one unit.

[0059] The above embodiments are only used to illustrate the technical solutions of the present application, but not to limit it; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can understand that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not drive the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A runoff simulation method based on a loosely coupled hydrological model of glacier and non-glacier partitions, characterized by: The method comprises the following steps: S1. Divide the target watershed with mixed recharge sources into glaciated and non-glaciated areas; S2. Grid the target watershed based on the DEM to divide it into multiple grid cells, which serve as basic calculation units. Count and output the area ratio of glaciated to non-glaciated areas in each calculation unit. S3. Simulate runoff generation in the target watershed using a distributed hydrological model. Considering the proportion of non-glaciated areas in each grid cell, use the model's surface runoff module to calculate daily runoff output in the non-glaciated areas and generate a simulated runoff sequence. S4. Conduct differentiated modeling of the glacier area based on the distributed enhanced temperature index model and output daily runoff simulation results for the glacier area; S5. Combine the runoff simulation series in the non-glaciated area and the daily runoff results in the glaciated area to obtain the total simulated runoff of the basin.

2. A runoff simulation method based on a loosely coupled hydrological model of glacier and non-glacier partitions according to claim 1, characterized in that: In the gridding process of the target watershed based on the DEM, the grid resolution is set in the range of 0.05 to 0.25°.

3. The runoff simulation method based on the loosely coupled hydrological model of glacier and non-glacier partitions according to claim 1 is characterized in that: Step S3 includes: S301. Assign a grid ID to the grid cell and record the longitude and latitude coordinates of its center point as a spatial index of the model input file; S302. Configure meteorological variables for the grid cell, including daily precipitation, maximum temperature, minimum temperature and wind speed; S303. Configure basic input parameters for the grid unit, including soil parameter files, vegetation parameter files, and elevation parameter files; S304. Calibrate model parameters based on measured runoff data at the watershed outlet. The model parameters include: Infilt, Ds, Dsmax, Ws, and the depths of the second and third soil layers. The calibration objectives are to maximize the Nash efficiency coefficient and minimize the relative deviation. S305. Combine the distributed hydrological model after parameter calibration and the runoff results of the grid model with the area ratio of the non-glaciated area to calculate and generate the daily runoff simulation sequence for the non-glaciated area. The expression is: Q1,j=f·Q2,j Where Q1,j is the simulated runoff of the non-glaciated area in the target area on the jth day, f is the area ratio of the non-glaciated area, and Q2,j is the total simulated runoff of the non-glaciated area in the target area model on the jth day.

4. The runoff simulation method based on the loosely coupled hydrological model of glacier and non-glacier partitions according to claim 3 is characterized in that: The basic input parameters include: Soil parameter file, which defines the thickness of each soil layer, initial moisture content, saturated hydraulic conductivity, water diffusion coefficient, and base flow curve parameters; Vegetation parameter files record the distribution ratio and root depth of various types of vegetation, and call the monthly scale LAI, minimum stomatal resistance, albedo and roughness parameters preset in the vegetation library file; The elevation parameter file subdivides each grid cell into multiple elevation bands, and configures the area ratio, average elevation, and precipitation ratio of each band.

5. The runoff simulation method based on the loosely coupled hydrological model of glacier and non-glacier partitions according to claim 3 is characterized in that: Determining the model parameters comprises the following steps: Based on the measured runoff, the runoff of the target basin is simulated based on the distributed hydrological model to obtain the total simulated runoff sequence of the entire basin; Compare the simulated total runoff with the measured runoff, calculate the Nash efficiency coefficient and relative deviation and use them as calibration indicators; By adjusting the model parameters, the optimal model parameter combination is obtained with the goal of maximizing the Nash efficiency coefficient and minimizing the relative deviation.

6. The runoff simulation method based on the loosely coupled hydrological model of glacier and non-glacier partitions according to claim 1 is characterized in that: Step S4 includes: S401. Dividing the glacier area into simulation grids at a set resolution; S402. Based on the DEM data, terrain correction and spatial interpolation are performed on key meteorological elements on the simulation network to form input data consistent with the model resolution; S403. In combination with the input data, the traditional degree-day factor method or the temperature index method that introduces clear-sky solar radiation is used to simulate the glacier meltwater generation and confluence process. When the Nash efficiency coefficient and relative deviation between the measured runoff and the total simulated runoff are optimal, the glacier model parameters at this time are optimal, corresponding to the calculated daily simulated runoff results for the glacier area.

7. The runoff simulation method based on the loosely coupled hydrological model of glacier and non-glacier partitions according to claim 6 is characterized in that: In step S403, the traditional degree-day factor method is used to simulate the glacier meltwater generation and confluence process, and the expression is: M ； Where M is the melting rate of ice, in mm / h; DDF ice The degree-day factor of ice is expressed in mm / day / °C, which indicates the amount of meltwater caused by each unit of positive air temperature; T is the air temperature, in °C, which drives the melting process when the temperature is positive; n represents the time step; The temperature index method of clear sky solar radiation is introduced to simulate the generation and confluence of glacier meltwater. The expression is: M ； in, MF is the basic melt factor, with the unit of mm / day / ℃, which represents the amount of meltwater per unit positive temperature condition; is the ice radiation coefficient, which is used to characterize the enhancement effect of solar radiation on the melting process; I Indicates the potential solar radiation under clear sky conditions in W / m².

8. The runoff simulation method based on the loosely coupled hydrological model of glacier and non-glacier partitions according to claim 7 is characterized in that: Step S5 includes: Calculation of runoff in non-glaciated areas based on runoff simulation series in non-glaciated areas ; According to the runoff volume of glacier area and non-glaciated area runoff Determine the total outlet simulated runoff Q; ; Taking the maximization of Nash efficiency coefficient and the minimization of relative deviation as the optimization objectives, the hydrological parameters in the glacier area are optimized and adjusted, and the total outlet simulated runoff Q driven by the optimal parameter combination is output.

9. A runoff simulation system based on a loosely coupled hydrological model of glacier and non-glacier partitions, used to implement the runoff simulation method according to any one of claims 1 to 8, characterized in that: The system comprises: A zoning module is used to divide the target watershed with mixed recharge sources into glaciated and non-glaciated areas; The grid processing module is used to perform grid processing on the target watershed based on the DEM, so as to divide it into multiple grid cells as basic calculation units, and to count and output the area ratio of glacier area to non-glacier area in each calculation unit; The non-glaciated area simulation module is used to simulate the runoff generation process of the target basin based on the distributed hydrological model. Based on the area ratio of the non-glaciated area in each grid cell, the surface runoff module of the model is used to calculate the daily runoff output of the non-glaciated area and generate its runoff simulation sequence. The glacier simulation module is used to perform differentiated modeling of the glacier area based on the distributed enhanced temperature index model and output daily runoff simulation results of the glacier area; Combined with the fusion module, it is used to fuse the runoff simulation series in the non-glaciated area and the daily runoff results in the glaciated area to obtain the total simulated runoff in the basin.

10. An application of a runoff simulation method based on a loosely coupled hydrological model of glacier and non-glacier partitions according to any one of claims 1 to 8, characterized in that: The method is applied to simulate runoff in a typical glacial-non-glacial mixed-recharge basin in alpine mountainous areas.

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