Method and system for calculating snowmelt runoff based on snow water equivalent distribution curve

Abstract

The application provides a method and system for calculating snowmelt runoff based on snow water equivalent distribution curve, and relates to the technical field of hydrological forecasting. The method comprises the following steps: cumulative calculation is performed on the collected environmental data by using a temperature threshold segmentation method to obtain total snow water equivalent; a snow water equivalent distribution curve is constructed according to the total snow water equivalent and the area proportion of the snow-covered area, and the snow water equivalent distribution curve and the total snow water equivalent are integrally correlated to obtain a maximum snow water equivalent value; based on the environmental data, a potential cumulative snowmelt amount is calculated by using a degree-day factor method; a unit time period snowmelt amount is calculated according to the snow water equivalent distribution curve, the maximum snow water equivalent value and the potential cumulative snowmelt amount; and the unit time period snowmelt amount is converted into snowmelt runoff of each time period by using a linear reservoir method. The method has the advantages of less data requirement, simple parameters and strong adaptability, can effectively avoid the dependence on remote sensing observation, and improves the reliability of the cold region basin runoff prediction and water resource scheduling management.

Description

Technical Field

[0001] This invention relates to the field of hydrological forecasting technology, and in particular to a method and system for calculating snowmelt runoff based on snow water equivalent distribution curves. Background Technology

[0002] In high-altitude and cold mountainous areas, the formation and melting of snow are crucial factors influencing the temporal distribution of watershed runoff. Snow accumulates in winter and gradually melts in spring, replenishing rivers and forming high-water runoff, which plays a decisive role in downstream water supply, flood control, and water resource allocation. Accurately simulating the snow accumulation and snowmelt runoff process is an important research topic in cold region hydrological simulation.

[0003] Existing methods for calculating snowmelt runoff mainly include: 1) Temperature index method (degree-day factor method): This method estimates snowmelt volume based on the empirical relationship between air temperature and snowmelt volume, and has the advantages of simple calculation and low data requirements; however, this method relies solely on air temperature and fails to effectively consider the spatial distribution characteristics of snow cover, making it difficult to accurately reflect the heterogeneity of snowmelt under different terrain conditions. 2) Energy balance method: This method calculates snowmelt volume through energy budget relationships such as radiation, convection, and heat conduction, which is theoretically more comprehensive, but has extremely high requirements for input data, requiring multiple meteorological elements (such as radiation, wind speed, humidity, etc.). In high-altitude and cold mountainous areas, there is often a lack of sufficient observation data, making it difficult to promote its application in actual watersheds, and it fails to accurately depict the accumulation and melting process of snow cover. 3) Snow cover simulation method based on remote sensing inversion: This method obtains snow cover area or snow depth data through satellite remote sensing, and then calculates snow water equivalent and snowmelt process; although this method can reflect spatial distribution, it is limited by factors such as the temporal resolution, spatial resolution, and cloud cover of remote sensing images, making it difficult to continuously and stably obtain long-term series, and the accuracy of remote sensing products is uncertain. Therefore, it is essential to design a method and system for calculating snowmelt runoff based on snow water equivalent distribution curves. Summary of the Invention

[0004] The purpose of this invention is to provide a method and system for calculating snowmelt runoff based on snow water equivalent distribution curves. The method obtains the watershed snow water equivalent using temperature and precipitation data, and then combines the degree-day factor method for simplified calculation to improve the accuracy and applicability of snowmelt runoff simulation.

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

[0006] A method for calculating snowmelt runoff based on snow water equivalent distribution curves includes the following steps:

[0007] The total snow water equivalent was obtained by cumulatively calculating the collected environmental data using the temperature threshold segmentation method; the environmental data included: daily precipitation and daily average temperature.

[0008] A snow water equivalent distribution curve is constructed based on the total snow water equivalent and the proportion of snow cover area. The snow water equivalent distribution curve and the total snow water equivalent are integrally correlated to obtain the maximum snow water equivalent value.

[0009] Based on environmental data, the potential cumulative snowmelt volume was calculated using the day-of-day factor method.

[0010] The amount of snowmelt per unit time period is calculated based on the snowmelt equivalent distribution curve, the maximum snowmelt equivalent value, and the potential cumulative snowmelt amount.

[0011] The linear reservoir method is used to convert the amount of snowmelt per unit time period into snowmelt runoff in different time periods.

[0012] Optionally, the collected environmental data can be cumulatively calculated using a temperature threshold segmentation method to obtain the total snow water equivalent, including:

[0013] Based on the average daily temperature and the preset snowmelt initiation temperature threshold, daily precipitation is divided into daily snowfall and daily rainfall;

[0014] The total snow water equivalent is obtained by accumulating the daily snowfall over an annual period.

[0015] Optionally, a snow water equivalent distribution curve is constructed based on the total snow water equivalent and the proportion of snow-covered area, and the snow water equivalent distribution curve and the total snow water equivalent are integrally correlated to obtain the maximum snow water equivalent value, including:

[0016] A snow water equivalent distribution curve is constructed with the total snow water equivalent as the ordinate and the percentage of snow-covered area as the abscissa; the expression for the snow water equivalent distribution curve is:

[0017] ;

[0018] in, This refers to the snow water equivalent at various points within the total snow water equivalent. For the entire basin area, The proportion of the total watershed area that has not accumulated snow. This is the maximum snow water equivalent value. The parameter is not uniformly distributed;

[0019] Construct the integral relationship between total snowmelt equivalent and snowmelt equivalent distribution curve; the expression for the integral relationship is:

[0020] ;

[0021] in Total snowmelt equivalent;

[0022] The maximum snowmelt equivalent value is calculated based on the integral relationship; the formula for calculating the maximum snowmelt equivalent value is:

[0023] .

[0024] Optionally, based on environmental data, the potential cumulative snowmelt amount is calculated using the daily degree factor method. Specifically, it is determined whether snowmelt has occurred based on the daily average temperature and a preset snowmelt initiation temperature threshold. If so, the potential cumulative snowmelt amount is calculated. The formula for calculating the potential cumulative snowmelt amount is:

[0025] ;

[0026] in, This represents the potential cumulative snowmelt volume. For daily living factors, For the first t Temperature for each calculation period, This is the threshold temperature for the onset of snow melting.

[0027] Optionally, the snowmelt amount per unit time period is calculated based on the snowmelt equivalent distribution curve, the maximum snowmelt equivalent value, and the potential cumulative snowmelt amount, including:

[0028] The relative area value was obtained based on the snow water equivalent distribution curve and the potential cumulative snow melt amount;

[0029] The actual cumulative snowmelt volume is calculated based on the relative area value.

[0030] Based on the maximum snow water equivalent value, an integral and simultaneous operation is performed on the actual cumulative snow melt volume to obtain the cumulative snow melt runoff equation set;

[0031] The cumulative snowmelt runoff equations are solved to obtain the snowmelt amount per unit time period.

[0032] Alternatively, the expression for the linear reservoir method is: ;

[0033] in, For unit conversion factor, This is the snowmelt runoff recession coefficient. This is the runoff from the previous snowmelt. For the current snowmelt runoff, This represents the amount of snow melted per unit of time period.

[0034] A system for calculating snowmelt runoff based on snow water equivalent distribution curves includes:

[0035] The total amount calculation module is used to accumulate and calculate the total snow water equivalent by using the temperature threshold segmentation method to collect environmental data; the environmental data includes: daily precipitation and daily average temperature;

[0036] The model building module is used to construct the snow water equivalent distribution curve based on the total snow water equivalent and the proportion of snow cover area, and to perform integral correlation between the snow water equivalent distribution curve and the total snow water equivalent to obtain the maximum snow water equivalent value.

[0037] The prediction module is used to calculate the potential cumulative snowmelt based on environmental data using the day-of-day factor method.

[0038] The actual calculation module is used to calculate the amount of snow melt per unit time period based on the snow water equivalent distribution curve, the maximum snow water equivalent value, and the potential cumulative snow melt amount.

[0039] The snowmelt runoff calculation module is used to convert the snowmelt volume per unit time period into snowmelt runoff for each time period using the linear reservoir method.

[0040] The beneficial effects of this invention are as follows: The method and system for calculating snowmelt runoff based on snow water equivalent distribution curves provided by this invention are the first to introduce snow water equivalent distribution curves into the snowmelt calculation process, breaking through the limitations of traditional temperature index methods and energy balance methods. This allows for accurate characterization of the spatiotemporal distribution characteristics of watershed snow accumulation even when relying solely on basic meteorological data such as air temperature and precipitation, thereby significantly improving the accuracy and stability of snowmelt runoff simulation. Furthermore, by introducing snowless area ratio parameters and non-uniformity index parameters, this method can flexibly describe the differences in snow accumulation distribution in different watersheds and different years, balancing the simplicity and physical meaning of the model. Simultaneously, a quantitative relationship between total snow water equivalent, maximum snow water equivalent, and snow accumulation distribution curves is established based on the core integral formula, demonstrating strong innovation and operability. It has also formed a complete technical route of "snow accumulation estimation - distribution curve construction - potential snowmelt calculation - actual snowmelt estimation - runoff simulation", which can be directly embedded into hydrological models and watershed water resource scheduling systems. It is particularly suitable for application scenarios such as runoff prediction, reservoir scheduling, and snow and ice flood forecasting in high-altitude mountainous areas and areas with scarce data. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 This is a flowchart of the snowmelt runoff calculation method according to an embodiment of the present invention;

[0043] Figure 2 This is a schematic diagram of the snow water equivalent distribution curve according to an embodiment of the present invention;

[0044] Figure 3This is a schematic diagram of the snowmelt runoff calculation system according to an embodiment of the present invention. Detailed Implementation

[0045] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0046] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0047] like Figure 1 As shown in the figure, this invention provides a method for calculating snowmelt runoff based on snow water equivalent distribution curves, including the following steps:

[0048] Step 100: The collected environmental data are cumulatively calculated using the temperature threshold segmentation method to obtain the total snow water equivalent; the environmental data includes: daily precipitation and daily average temperature;

[0049] Step 200: Construct a snow water equivalent distribution curve based on the total snow water equivalent and the proportion of snow cover area, and perform an integral correlation between the snow water equivalent distribution curve and the total snow water equivalent to obtain the maximum snow water equivalent value;

[0050] Step 300: Based on environmental data, calculate the potential cumulative snowmelt using the day-of-day factor method;

[0051] Step 400: Calculate the snowmelt amount per unit time period based on the snow water equivalent distribution curve, the maximum snow water equivalent value, and the potential cumulative snowmelt amount;

[0052] Step 500: Convert the snowmelt volume per unit time period into snowmelt runoff for each time period using the linear reservoir method.

[0053] In this embodiment, step 100 collects daily precipitation and average daily temperature in the study area. During the snow cover period, daily precipitation is divided into rain and snowfall using a temperature threshold segmentation method. Precipitation below the threshold is classified as snowfall. Then, the daily snowfall is accumulated to obtain the total snow water equivalent of the basin during the study year. Specifically, the preset snowmelt initiation temperature threshold is 0℃. In some other embodiments, this threshold is used as a parameter for calibration, ranging from [-4, 2]. The average daily temperature is used... T t The daily precipitation will be related to the snowmelt onset temperature threshold. P t Classified by snowfall and rainfall Then, using a year as a calculation cycle, and the period from the first day to the last day of snowfall as the snow accumulation period, the total annual snow water equivalent of the basin is obtained by summing up the snowfall amounts. The calculation formula is as follows: .

[0054] like Figure 2 As shown, in this embodiment, step 200 is based on the total snow water equivalent. Plot a snowmelt equivalent distribution curve against the proportion of snow-covered area, integrate the snowmelt equivalent distribution curve, and then compare the integrated value with the total snowmelt equivalent. An equation was established to obtain the maximum snowmelt equivalent value within the watershed. Specifically, the snowmelt equivalent distribution curve reflects the spatial distribution characteristics of snowmelt equivalent within the watershed during the study year, using snowmelt equivalent... SW The vertical axis is , SWM The maximum snowmelt equivalent value within the watershed, expressed as a relative value by area. The x-axis is... For the snow water equivalent within the basin to be less than or equal to SW area, F For the entire basin area The horizontal axis represents the proportion of the unsnow-covered area to the total watershed area. The snowmelt equivalent distribution curve, constructed to represent the actual accumulated snowmelt flow, is approximately described by an exponential equation, expressed as:

[0055] ;

[0056] in, b This is a parameter representing uneven distribution, ranging from 0 to 1, reflecting the uneven distribution of snowmelt equivalent within the watershed. b The smaller the value, the more uniform the uniformity. b =0 indicates that the equivalent snowmelt in the watershed is uniform and constant, while b A larger value indicates greater unevenness. Then, a relationship is established between the total snowmelt equivalent and the snowmelt equivalent distribution curve through integration, expressed as:

[0057] ;

[0058] Finally, the maximum snowmelt equivalent value within the watershed is calculated based on the integral relationship. The calculation formula is as follows:

[0059] .

[0060] In this embodiment, step 300 utilizes the degree-day factor method, combining the daily average temperature with the snowmelt initiation temperature threshold to calculate the daily positive accumulated temperature, thereby obtaining the potential cumulative snowmelt amount. Specifically, the relationship between the daily average temperature and the snowmelt initiation temperature threshold is compared to determine whether snowmelt has occurred. When snowmelt has occurred, the cumulative positive accumulated temperature for each period during the snowmelt period is calculated, thus obtaining the cumulative accumulated temperature from the start of snowmelt to the calculated period. tPotential cumulative snowmelt flow SM t The calculation formula is:

[0061] ;

[0062] in, The day factor (used as a model parameter for calibration). For the first t Temperature for each calculation period, This is the threshold temperature for the onset of snow melting.

[0063] In this embodiment, step 400 uses the integral relationship of the snow water equivalent distribution curve to allocate the potential cumulative snowmelt amount to each snow-covered area within the watershed, thereby calculating the actual cumulative snowmelt amount and further obtaining the snowmelt amount per unit time period. Specifically, based on the snow water equivalent distribution curve and the potential cumulative snowmelt amount, the potential cumulative snowmelt amount is first obtained... SM t The corresponding relative area value is expressed as:

[0064] ;

[0065] This relative area value represents the area up to... t At any time, there are within the basin The entire area of ​​snow has melted. The snow cover over a certain area has partially melted. The estimated actual cumulative snow melt volume at this point is:

[0066] ;

[0067] in The actual accumulated snowmelt flow rate is obtained after integration: Then, by performing a simultaneous integration operation, we obtain the cumulative snowmelt runoff equation system, which is expressed as:

[0068] ;

[0069] Finally, the snowmelt amount per unit time period was obtained. .

[0070] In this embodiment, step 500 combines the linear reservoir method to convert the snowmelt volume per unit time period into snowmelt runoff for each time period. Specifically, the runoff generation of the snowmelt volume per unit time period is simulated using a linear reservoir, and the expression is:

[0071] ;in, Using the unit conversion factor, for daily runoff simulation with a time step of 24 hours, then... , The area of ​​the grid cell. This is the snowmelt runoff recession coefficient. This is the runoff from the previous snowmelt. For the current snowmelt runoff, for the initial time... t When =1, this embodiment takes .

[0072] like Figure 3 As shown, this embodiment of the invention also provides a system for calculating snowmelt runoff based on snow water equivalent distribution curves, comprising:

[0073] The total amount calculation module is used to accumulate and calculate the total snow water equivalent by using the temperature threshold segmentation method to collect environmental data; the environmental data includes: daily precipitation and daily average temperature;

[0074] The model building module is used to construct the snow water equivalent distribution curve based on the total snow water equivalent and the proportion of snow cover area, and to perform integral correlation between the snow water equivalent distribution curve and the total snow water equivalent to obtain the maximum snow water equivalent value.

[0075] The prediction module is used to calculate the potential cumulative snowmelt based on environmental data using the day-of-day factor method.

[0076] The actual calculation module is used to calculate the amount of snow melt per unit time period based on the snow water equivalent distribution curve, the maximum snow water equivalent value, and the potential cumulative snow melt amount.

[0077] The snowmelt runoff calculation module is used to convert the snowmelt volume per unit time period into snowmelt runoff for each time period using the linear reservoir method.

[0078] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0079] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A method for calculating snowmelt runoff based on snow water equivalent distribution curves, characterized in that, Includes the following steps: The total snow water equivalent is obtained by cumulatively calculating the collected environmental data using the temperature threshold segmentation method; the environmental data includes: daily precipitation and daily average temperature; A snow water equivalent distribution curve is constructed based on the total snow water equivalent and the proportion of snow cover area. The snow water equivalent distribution curve and the total snow water equivalent are then integrally correlated to obtain the maximum snow water equivalent value. Based on the environmental data, the potential cumulative snowmelt volume was calculated using the day-of-day factor method. The amount of snowmelt per unit time period is calculated based on the snowmelt equivalent distribution curve, the maximum snowmelt equivalent value, and the potential cumulative snowmelt amount. The snowmelt volume per unit time period is converted into snowmelt runoff for each time period using the linear reservoir method; A snow water equivalent distribution curve is constructed based on the total snow water equivalent and the proportion of snow cover area. The maximum snow water equivalent value is obtained by integrating the distribution curve and the total snow water equivalent, including: Using the total snow water equivalent as the vertical axis and the proportion of the snow-covered area as the horizontal axis, construct the snow water equivalent distribution curve; The expression for the snow water equivalent distribution curve is: ;in, This refers to the snow water equivalent at each point in the total snow water equivalent. For the entire basin area, This represents the proportion of the unsnow-covered area to the total watershed area. SWM The maximum snow water equivalent value, b The parameter is not uniformly distributed; Construct an integral relationship between the total snowmelt equivalent and the snowmelt equivalent distribution curve; the expression for the integral relationship is: ;in The total snow water equivalent; The maximum snowmelt equivalent value is calculated based on the integral relationship; the formula for calculating the maximum snowmelt equivalent value is as follows: .

2. The method for calculating snowmelt runoff based on the snow water equivalent distribution curve according to claim 1, characterized in that, The total snow water equivalent is obtained by cumulatively calculating the collected environmental data using the temperature threshold segmentation method, including: The daily precipitation is divided into daily snowfall and daily rainfall based on the average daily temperature and a preset snowmelt initiation temperature threshold. The total snow water equivalent is obtained by cumulatively calculating the daily snowfall over an annual period.

3. The method for calculating snowmelt runoff based on snow water equivalent distribution curve according to claim 1, characterized in that, Based on the aforementioned environmental data, the potential cumulative snowmelt amount was calculated using the day-of-day factor method, specifically as follows: Whether snow melting has occurred is determined based on the average daily temperature and the preset snow melting initiation temperature threshold. If so, the potential cumulative snowmelt amount is calculated; the formula for calculating the potential cumulative snowmelt amount is: ;in, This refers to the potential cumulative snowmelt. For daily living factors, For the first t Temperature for each calculation period, The threshold temperature for the start of snow melting is denoted as .

4. The method for calculating snowmelt runoff based on snow water equivalent distribution curve according to claim 1, characterized in that, The snowmelt amount per unit time period is calculated based on the snow water equivalent distribution curve, the maximum snow water equivalent value, and the potential cumulative snowmelt amount, including: The relative area value is obtained based on the snow water equivalent distribution curve and the potential cumulative snow melt amount; The actual cumulative snow melt volume is calculated based on the relative area value. Based on the maximum snow water equivalent value, an integral and simultaneous operation is performed on the actual cumulative snow melt volume to obtain the cumulative snow melt runoff equation set. The cumulative snowmelt runoff equations are solved to obtain the snowmelt amount per unit time period.

5. The method for calculating snowmelt runoff based on snow water equivalent distribution curve according to claim 1, characterized in that, The expression for the linear reservoir method is: ;in, U For unit conversion factor, C This is the snowmelt runoff recession coefficient. This is the runoff from the previous snowmelt. For the current snowmelt runoff, The amount of snow melted per unit time period.

6. A system for calculating snowmelt runoff based on snow water equivalent distribution curve, used to implement the method for calculating snowmelt runoff based on snow water equivalent distribution curve as described in any one of claims 1-5, characterized in that, include: The total amount calculation module is used to accumulate and calculate the total snow water equivalent by using the temperature threshold segmentation method to collect environmental data; The environmental data includes: daily precipitation and average daily temperature; The model building module is used to construct a snow water equivalent distribution curve based on the total snow water equivalent and the proportion of snow cover area, and to perform an integral correlation between the snow water equivalent distribution curve and the total snow water equivalent to obtain the maximum snow water equivalent value. The prediction module is used to calculate the potential cumulative snowmelt amount based on the environmental data using the day-of-day factor method; The actual calculation module is used to calculate the snowmelt amount per unit time period based on the snowmelt equivalent distribution curve, the maximum snowmelt equivalent value, and the potential cumulative snowmelt amount. The snowmelt runoff calculation module is used to convert the snowmelt volume per unit time period into snowmelt runoff for each time period using the linear reservoir method.

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