Drought early warning method and system for whole growth period of crops in rain-fed region

Abstract

The invention provides a drought early warning method and system for the whole growth period of crops in a rain-fed region. According to the method, soil moisture prediction and drought early warning are carried out, influences of crop growth requirements and soil moisture changes are considered, and then drought early warning is carried out on crops in the rain-fed region from any time of the whole growth period to a preset time period in the future, so that the comprehensiveness and the applicability of the early warning technology are improved.

Description

Technical Field

[0001] The present application relates to a drought early warning method and system for the entire growth period of crops in rain-fed areas, belonging to the technical field of drought early warning. Background Art

[0002] Rain-fed areas refer to those areas that rely mainly on natural precipitation for agricultural production. Early warning of crop drought in rain-fed areas is very important. For example, it can help farmers understand the possibility of drought weather in a timely manner, so as to adjust their planting plans, such as choosing drought-resistant crops or appropriate irrigation measures, thereby reducing potential losses.

[0003] Existing drought warning technologies for rain-fed areas include: 1. Drought warning based on rainfall and soil moisture monitoring: using rainfall forecasts and soil moisture monitoring data for drought warning; 2. Drought warning based on crop demand: using rainfall and evaporation from meteorological data to assess crop moisture gaps, and using relevant indicators for drought warning.

[0004] However, the objective shortcomings of existing drought early warning technologies include: 1. Lack of technology that comprehensively considers water loss in various processes and the actual supply and demand of crops: Existing drought early warning technologies often focus on meteorological data and crop potential evapotranspiration, but do not take into account the impact of soil moisture changes on the actual water absorption of crops. 2. Lack of practical application technology for drought early warning in combination with relevant soil-crop mechanism models and drought indicators: Previous technologies were only used in drought assessment, and lacked real applications for drought early warning at preset times in the future. Summary of the invention

[0005] The present application provides a drought early warning method and system for the entire growth period of crops in rain-fed areas, in order to solve the problems in the current scheme of lacking comprehensive consideration of water loss in various processes and the actual supply and demand of crops, as well as the lack of practical application technology for drought early warning.

[0006] In order to achieve the above objectives, this application provides the following technical solutions: In a first aspect, an embodiment of the present application provides a drought early warning method for crops in rain-fed areas during the entire growth period, comprising: Obtaining the latitude and longitude data of the target location, and obtaining the data required for early warning and historical data of the target location from a database according to the latitude and longitude data; the data required for early warning and the historical data both include meteorological data, soil parameter data, crop growth parameter data simulated based on a pre-built crop growth model, initial soil moisture data, and preset parameters; Based on the data required for the early warning, the pre-constructed soil water balance equation is used to calculate the potential transpiration and actual transpiration of the crop every day within a preset time in the future, and then the daily crop soil water deficit index is calculated based on the potential transpiration and actual transpiration; wherein, the soil water balance equation takes into account the influence of crop root depth, canopy interception and surface runoff, and soil leakage on the actual transpiration of the crop; and, based on the historical data, using a pre-constructed soil water balance equation, calculating an average value of the crop soil water deficit index in a corresponding time period; Based on the daily crop soil moisture deficit index and the daily weight coefficient, the cumulative crop soil moisture deficit index for the future period is calculated; based on the average of the cumulative crop soil moisture deficit index and the crop soil moisture deficit index, the crop soil moisture deficit anomaly index is calculated; Based on the agricultural drought grade standard, the crop water deficit deviation index is replaced with the crop soil water deficit deviation index, the drought grade is determined, and the warning result is output; Wherein, in the soil water balance equation, the soil is divided into a root layer and a non-root layer; The soil water balance equation at the root layer is expressed as:

[0007] In the formula, The soil moisture content in the root layer of the next day, in cm 3 cm -3 (or expressed as cm 3 / cm 3 , that is, per cm 3 The water content of the soil is the same below. For example, assuming , which means the root layer per cm in the next day 3 The water content of the soil is cm 3 ); The actual root depth of the crop on the next day, in cm; is the soil moisture content in the root layer on that day, in cm 3 cm -3 ; The actual root depth of the crop on that day, in cm; Predicted rainfall for the next day in cm; is the soil moisture content in the non-root layer on that day, in cm 3 cm -3 ; is the canopy interception for the next day, in cm; is the runoff of the next day, in cm; is the actual evapotranspiration of crops, in cm; is the root layer leakage, in cm; The soil water balance equation of the non-root layer is expressed as:

[0008] in, The non-root layer soil moisture content of the next day, in cm 3 cm -3 ; is the maximum root depth, in cm; is the soil moisture content in the non-root layer on that day, in cm 3 cm -3 ; is the deep leakage, in cm; The processes involved in the soil water balance equation include: simulation of root depth, canopy interception and surface runoff, evapotranspiration and infiltration; ① The root depth is simulated by a sinusoidal function. The current root depth is related to the relative growth time of the current root and the maximum root depth, expressed as:

[0009] In the formula, is the current growth day; is the total growing days, and is the crop parameter: ②The calculation formula for canopy interception is:

[0010]

[0011] In the formula, is the canopy interception, a is the empirical coefficient, and the value of crops is 0.0025; is the leaf area index; is the soil coverage; To predict rainfall; The calculation formula for surface runoff is:

[0012]

[0013] In the formula, is the surface runoff, is the maximum possible infiltration, in cm; is the runoff index; ③ The calculation formula for crop potential evapotranspiration is:

[0014] in, is the crop potential evapotranspiration, in cm; is the crop coefficient; is the crop reference evapotranspiration, in cm, derived from meteorological data; use calculate:

[0015] and They are =0 and The crop coefficient at maximum, It is an empirical parameter with a reference range of 0.5-1; Potential evaporation of soil and crop potential evapotranspiration Depend on calculate:

[0016]

[0017] in, is the soil potential evaporation, in cm; is the crop potential transpiration, in cm; Actual soil evaporation The calculation is as follows:

[0018] in, It is an empirical parameter and is related to soil texture; The actual transpiration is calculated as follows:

[0019]

[0020]

[0021] in, is the crop water absorption stress threshold, in cm 3 cm -3 ; is the moisture content at the wilting point, in cm 3 cm -3 ; is the field water holding capacity, in cm 3 cm -3 ; and is the crop coefficient value, and the value of each crop is based on the FAO recommended value; The actual evapotranspiration is calculated as follows:

[0022] in, is the actual evapotranspiration, in cm; ④ The amount of leakage from the root layer to the non-root layer is calculated as:

[0023] After the root leakage is calculated, the total water volume in the non-root layer is calculated according to the soil water balance equation of the non-root layer. If the total water volume is greater than the field water holding capacity, the part exceeding the field water holding capacity will seep into the deep layer. At this time, the total water volume in the non-root layer is .

[0024] Based on the above method, optionally, the calculation formula of the crop soil moisture deficit index is:

[0025] In the formula, Indicates The crop soil moisture deficit index for the day, Indicates The actual evaporation per day, Indicates Daily potential evaporation.

[0026] Based on the above method, optionally, the calculation formula of the cumulative crop soil moisture deficit index for a period of time in the future is:

[0027] In the formula, is the cumulative crop soil moisture deficit index for the next m days, , , , , …are weight coefficients, which add up to 1.

[0028] Based on the above method, optionally, the calculation formula of the crop soil moisture deficit anomaly index is:

[0029] In the formula, It represents the crop soil moisture deficit anomaly index. represents the cumulative crop soil water deficit index, Represents the average value of crop soil water deficit index.

[0030] In a second aspect, an embodiment of the present application further provides a drought warning system for the entire growing period of crops in rain-fed areas, which includes a processing module, and the processing module is used to execute the drought warning method for the entire growing period of crops in rain-fed areas as described in any one of the first aspects.

[0031] Based on the above system, optionally, it includes: Big data server, used to store data required for early warning and historical data; A model operation server, used to store preset algorithms and models, and perform corresponding calculations using data obtained from the big data server; The interface server is used to deploy service interfaces, receive all web requests, and manage requests in a unified manner; Mobile APP, used to obtain the data to be displayed through the interface server The drought early warning method and system for the entire growth period of crops in rain-fed areas provided by the present application have the following beneficial effects compared with the prior art: 1. Stronger mechanism. This application improves the traditional drought index, taking into account the impact of soil moisture changes on crop growth, increasing the mechanism of the index and the credibility of drought warning results.

[0032] 2. Applicability of early warning: This application combines the soil-crop mechanism model with drought early warning indicators to truly provide early warning of crop water shortage in a preset time period in the future. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The accompanying drawings herein are incorporated into and constitute a part of the specification, illustrate embodiments consistent with the present application, and together with the specification are used to explain the principles of the present application. In addition, these drawings and text descriptions are not intended to limit the scope of the concept of the present application in any way, but to illustrate the concept of the present application for those skilled in the art by referring to specific embodiments.

[0034] Figure 1 A flow chart of a drought early warning method for crops in rain-fed areas during the entire growth period provided in one embodiment of the present application; Figure 2 A schematic diagram of a soil moisture prediction process provided by an embodiment of the present application; Figure 3 A schematic diagram of a drought warning process provided for an embodiment of the present application; Figure 4 A schematic diagram of the structure of a drought early warning system for crops throughout the growing period in rain-fed areas provided in one embodiment of the present application. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solutions and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0036] In order to solve the problems existing in the existing drought early warning technology, the present application provides a drought early warning scheme for the entire growth period of crops in rain-fed areas, performs soil moisture prediction and drought early warning, and considers the impact of crop growth requirements and soil moisture changes, thereby achieving drought early warning for a preset time period in the future from any time during the entire growth period of crops in rain-fed areas, thereby increasing the comprehensiveness and applicability of the early warning technology. The following non-limiting description of the specific implementation scheme is given through several examples or embodiments.

[0037] Some embodiments of the present application provide a drought early warning method for crops in rain-fed areas during the entire growth period, referring to Figure 1 , Figure 1 A flowchart of a drought early warning method for crops in rain-fed areas during their entire growth period is provided in accordance with an embodiment of the present application. Figure 1 As shown, the drought early warning method for crops in rain-fed areas during the entire growth period of this embodiment includes the following steps: Step S101: Obtain the latitude and longitude data of the target location, and obtain the data required for early warning and historical data of the target location from the database based on the latitude and longitude data; the data required for early warning and historical data include meteorological data, soil parameter data, crop growth parameter data simulated based on a pre-built crop growth model, initial soil moisture data and preset parameters.

[0038] Specifically, before applying this method, a database needs to be built in advance to store the corresponding meteorological and soil data. The required database consists of two parts: 1) Database required for early warning. Used to store data required for early warning, including: weather forecast data for future preset time, soil parameters at the point, daily LAI (Leaf Area Index) simulated by the pre-built crop growth mechanism model and the current crop growth stage, initial soil moisture data for the day, and other preset parameters stored separately according to longitude and latitude points.

[0039] 2) Database of the past n years. Used to store historical data of the past n years, including: meteorological data of the same period of each point in the past n years, soil parameters of the point, daily LAI and current crop growth stage simulated by pre-built crop growth model, initial soil moisture data and other preset parameters.

[0040] The data required for early warning of the target location is used to analyze and warn of future drought conditions at the target location, while historical data is used as a reference for calculation and processing.

[0041] Step S102: Based on the data required for early warning, the pre-constructed soil moisture balance equation is used to calculate the daily potential transpiration and actual transpiration of the crop within a preset time in the future, and then the daily crop soil moisture deficit index is calculated based on the daily potential transpiration and actual transpiration.

[0042] Specifically, existing drought early warning technologies often focus on meteorological data and crop potential evapotranspiration, but do not take into account the impact of soil moisture changes on the actual water absorption of crops, which leads to errors in moisture forecasts and thus the early warning results.

[0043] In this application, when pre-constructing the soil moisture balance equation, the effects of crop root depth, canopy interception and surface runoff, and soil leakage on the actual transpiration of crops are considered. In addition to considering the effects of rainfall and evapotranspiration on crop water supply, factors such as crop growth requirements (changes in crop root depth) and soil moisture changes (soil leakage) are also taken into account, making the results more accurate and comprehensive.

[0044] For example, the Agricultural Drought Grade Standard uses the Crop Water Deficitabnormal Index (CWDIa) to classify agricultural drought grades, which represents the difference between the normalized Crop Water Deficit Index (CWDI) and its average value. The Crop Water Deficit Index represents the percentage of the crop water requirement that cannot be met by external water. However, the Crop Water Deficit Index only considers the satisfaction of crop water supply by rainfall and evapotranspiration, but does not consider the impact of soil moisture changes on the actual water absorption of crops.

[0045] To address this issue, this application proposes a crop soil water deficit index (CSWDI), which comprehensively considers the supply and demand of the outside world and crops based on soil moisture prediction and crop growth conditions. It can be understood as the impact of water evaporated in the air and / or absorbed by the soil on the deficit index. The above impact is reflected in the data as the difference between potential transpiration and actual transpiration. Therefore, the actual transpiration needs to be calculated in drought warning, that is, the actual transpiration is dynamically changing data, and its changes are affected by the crop coefficient, canopy interception and leakage.

[0046] Furthermore, in some embodiments, when calculating the soil moisture content based on the soil moisture balance equation, it is first necessary to set the total simulation depth, and the total simulation depth is set to the maximum root depth, and the specific data is adjusted according to the actual crop.

[0047] In addition, in the soil water balance equation, the soil layer is divided into two layers: the root layer and the non-root layer. The root layer is the layer where the crop roots are located and moves with the growth of the crop roots.

[0048] The soil water balance equation at the root layer is expressed as:

[0049] In the formula, The soil moisture content in the root layer of the next day, in cm 3 cm -3 (or expressed as cm 3 / cm 3 , that is, per cm 3 Soil moisture content, the same below. For example, assuming , which means the root layer per cm in the next day 3 The water content of the soil is cm 3 ); The actual root depth of the crop on the next day, in cm; is the soil moisture content in the root layer on that day, in cm 3 cm -3 ; The actual root depth of the crop on that day, in cm; Predicted rainfall for the next day in cm; is the soil moisture content in the non-root layer on that day, in cm 3 cm -3 ; is the canopy interception for the next day, in cm; is the runoff of the next day, in cm; is the actual evapotranspiration of crops, in cm; is the root layer leakage, in cm; The non-root layer is the lower layer where the soil roots have not yet grown. The soil water balance equation of the non-root layer is expressed as:

[0050] in, The non-root layer soil moisture content of the next day, in cm 3 cm -3 ; is the maximum root depth, in cm; is the soil moisture content in the non-root layer on that day, in cm 3 cm -3 ; is the deep leakage, in cm.

[0051] It should be noted that this soil water balance equation assumes that rainfall enters the soil evenly, soil moisture is evenly distributed in the soil, and soil capillary absorption is not considered.

[0052] Based on the above soil water balance equation, the main processes involved include: root depth ( ) simulation, canopy interception ( ) and surface runoff ( ), evapotranspiration ( ) and leakage ( ). Further, they are: ① The root depth is simulated by a sinusoidal function. The current root depth is related to the relative growth time of the current root and the maximum root depth, expressed as:

[0053] In the formula, is the current growth day; is the total growing days, and is the crop parameter: ② Before rainfall enters the soil, some of the ineffective water will first be lost through canopy interception and surface runoff. Only the water that finally penetrates into the soil can be finally absorbed by the crop roots.

[0054] The calculation formula for canopy interception is:

[0055]

[0056] In the formula, is the canopy interception, a is the empirical coefficient, and the value of crops is 0.0025; is the leaf area index; is the soil coverage; To predict rainfall; The calculation formula for surface runoff is:

[0057]

[0058] In the formula, is the surface runoff, is the maximum possible infiltration, in cm; is the runoff index; in the standard SCS-CN (Soil Conservation Service Curve Number) method, The value is determined by factors such as hydrological conditions and land cover type.

[0059] ③ The calculation formula for crop potential evapotranspiration is:

[0060] in, is the crop potential evapotranspiration, in cm; is the crop coefficient; is the crop reference evapotranspiration, in cm, derived from meteorological data; use calculate:

[0061] and They are =0 and The crop coefficient at maximum, It is an empirical parameter with a reference range of 0.5-1; Potential evaporation of soil and crop potential evapotranspiration Depend on calculate:

[0062]

[0063] in, is the soil potential evaporation, in cm; is the crop potential transpiration, in cm; Actual soil evaporation The calculation is as follows:

[0064] in, It is an empirical parameter and is related to soil texture; Actual transpiration The calculation is as follows:

[0065]

[0066]

[0067] in, is the crop water absorption stress threshold, in cm 3 cm -3 ; is the moisture content at the wilting point, in cm 3 cm -3 ; is the field water holding capacity, in cm 3 cm -3 ; and is the crop coefficient value, and the value of each crop is based on the FAO recommended value; The actual evapotranspiration is calculated as follows:

[0068] in, is the actual evapotranspiration, in cm; ④ The amount of leakage from the root layer to the non-root layer is calculated as:

[0069] After the root leakage is calculated, the total water volume in the non-root layer is calculated according to the soil water balance equation of the non-root layer. If the total water volume is greater than the field water holding capacity, the part exceeding the field water holding capacity will seep into the deep layer. At this time, the total water volume in the non-root layer is .

[0070] When the root depth is equal to the maximum root depth, there is no non-root layer and there is no need to calculate the water content of the non-root layer and deep infiltration.

[0071] In actual application, refer to Figure 2 First, obtain the required data, calculate the above four processes ①-④ in sequence, and then calculate the soil moisture balance of the root layer and non-root layer. The variables saved and output include the soil moisture content of the root layer. wr Potential evaporation The actual evaporation . The calculation will continue until the last day of the preset time.

[0072] Afterwards, the daily crop soil water deficit index CSWDI is calculated based on the daily potential evapotranspiration and actual evapotranspiration.

[0073] The calculation formula of crop soil water deficit index CSWDI is:

[0074] In the formula, Indicates The crop soil moisture deficit index for the day, Indicates The actual evaporation per day, Indicates Daily potential evaporation.

[0075] Step S103: Based on the historical data, the average value of the crop soil moisture deficit index in the corresponding time period is calculated using the pre-constructed soil moisture balance equation.

[0076] Specifically, in this step, the crop soil moisture deficit index is calculated using a principle similar to step S102, and then the average value within the time period corresponding to the historical data is further calculated.

[0077] It should be noted that this step can be executed simultaneously with step S102, or they can be executed one after the other.

[0078] Step S104: Based on the daily crop soil water deficit index and the daily weight coefficient, the cumulative crop soil water deficit index for a period of time in the future is calculated, and based on the cumulative crop soil water deficit index and the average value of the crop soil water deficit index, the crop soil water deficit deviation index is calculated.

[0079] Specifically, the Crop Soil Water Deficit Index (CSWDI) can reflect the water shortage situation under the influence of crop coefficient, canopy interception and leakage. However, CSWDI does not take into account regional and seasonal differences. In other words, in different regions or seasons, even if CSWDI is the same, the actual water deficit of crops is different. In order to eliminate regional and seasonal differences, the Crop Soil Water Deficit Abnormal Index (CSWDIa) is proposed, which is the difference between the Crop Soil Water Deficit Index (CSWDI) and its average value.

[0080] During the calculation, firstly, based on the daily crop soil moisture deficit index and the daily weight coefficient, the cumulative crop soil moisture deficit index for the future period is calculated, and then based on the cumulative crop soil moisture deficit index and the average of the crop soil moisture deficit index, the crop soil moisture deficit deviation index is calculated.

[0081] The calculation formula for the cumulative crop soil moisture deficit index for a period of time in the future is:

[0082] In the formula, is the cumulative crop soil moisture deficit index for the next m days, , , , , …are weight coefficients, which add up to 1.

[0083] The calculation formula of crop soil moisture deficit anomaly index is:

[0084]

[0085] In the formula, It represents the crop soil moisture deficit anomaly index. represents the cumulative crop soil water deficit index, Represents the average value of crop soil water deficit index.

[0086] Step S105: Based on the agricultural drought grade standard, the crop water deficit deviation index is replaced with the crop soil water deficit deviation index, the drought grade is determined, and the warning result is output.

[0087] Specifically, when determining the drought level in this step, the standard proposed in the Agricultural Drought Level Standard is continued, except that the crop water deficit anomaly index is updated to the crop soil water deficit anomaly index proposed in this application. The specific drought levels are shown in Table 1.

[0088] Table 1 Based on crop soil moisture deficit anomaly index ( )

[0089] Based on the above scheme, the soil moisture prediction algorithm is used to predict moisture and drought warning for the preset time in the future, and the cumulative drought level in the preset time in the future can be output. The specific implementation process is as follows: Figure 3 Moreover, compared with the prior art, the solution of the present application has the following beneficial effects: 1. Stronger mechanism. This application improves the traditional drought index, taking into account the impact of soil moisture changes on crop growth, increasing the mechanism of the index and the credibility of drought warning results.

[0090] 2. Applicability of early warning: This application combines the soil-crop mechanism model with drought early warning indicators to truly provide early warning of crop water shortage in a preset time period in the future.

[0091] In addition, an embodiment of the present application provides a drought warning system for the entire growing period of crops in rain-fed areas, the system includes a processing module, and the processing module is used to execute the drought warning method for the entire growing period of crops in rain-fed areas described in any of the above embodiments.

[0092] Furthermore, if Figure 4 As shown, the system may include: Big data server, used to store data required for early warning and historical data; A model operation server, used to store preset algorithms and models, and perform corresponding calculations using data obtained from the big data server; The interface server is used to deploy service interfaces, receive all web requests, and manage requests in a unified manner; The mobile APP is used to obtain the data to be displayed through the interface server.

[0093] More specifically, the deployment and use of the system is as follows: Build a big data server to store weather, soil, crop variety and field operation data; deploy a computing server for model operations, and store algorithms including drought warning algorithm, soil moisture prediction algorithm and crop growth model on the computing server; build an interface server for the interface resource pool, and deploy the service interface through nginx, uWSGI and Django. Nginx is the front end of the server, receiving all web requests and managing requests in a unified manner. The APP application service adopts the front-end and back-end separation technology. When the APP needs to display content, it logs in to the interface server to obtain token information. When requesting the interface service, it accesses the service with the token; the server receives the request and verifies the token information, processes the request, and returns the result data.

[0094] It can be understood that the same or similar parts of the above embodiments can be referenced to each other, and the contents not described in detail in some embodiments can refer to the same or similar contents in other embodiments.

[0095] It should be noted that, in the description of the present invention, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. In addition, in the description of the present invention, unless otherwise specified, the meaning of "plurality" refers to at least two.

[0096] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, segment or portion of code that includes one or more executable instructions for implementing the steps of a specific logical function or process, and the scope of the preferred embodiments of the present invention includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in the reverse order depending on the functions involved, which should be understood by those skilled in the art to which the embodiments of the present invention belong.

[0097] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, a plurality of steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0098] A person skilled in the art may understand that all or part of the steps in the above-mentioned embodiment method may be completed by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, which, when executed, includes one or a combination of the steps of the method embodiment.

[0099] In addition, each functional unit in each embodiment of the present invention may be integrated into a processing module, or each unit may exist physically separately, or two or more units may be integrated into one module. The above-mentioned integrated module may be implemented in the form of hardware or in the form of a software functional module. If the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it may also be stored in a computer-readable storage medium. The above-mentioned storage medium may be a read-only memory, a disk or an optical disk, etc.

[0100] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0101] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A drought early warning method for crops in rain-fed areas during the entire growth period, characterized in that: include: Obtaining the latitude and longitude data of the target location, and obtaining the data required for early warning and historical data of the target location from a database according to the latitude and longitude data; the data required for early warning and the historical data both include meteorological data, soil parameter data, crop growth parameter data simulated based on a pre-built crop growth model, initial soil moisture data, and preset parameters; Based on the data required for the early warning, the pre-constructed soil water balance equation is used to calculate the potential transpiration and actual transpiration of the crop every day within a preset time in the future, and then the daily crop soil water deficit index is calculated based on the potential transpiration and actual transpiration; wherein, the soil water balance equation takes into account the influence of crop root depth, canopy interception and surface runoff, and soil leakage on the actual transpiration of the crop; and, based on the historical data, using a pre-constructed soil water balance equation, calculating an average value of the crop soil water deficit index in a corresponding time period; Based on the daily crop soil moisture deficit index and the daily weight coefficient, the cumulative crop soil moisture deficit index for the future period is calculated; based on the average of the cumulative crop soil moisture deficit index and the crop soil moisture deficit index, the crop soil moisture deficit anomaly index is calculated; Based on the agricultural drought grade standard, the crop water deficit deviation index is replaced with the crop soil water deficit deviation index, the drought grade is determined, and the warning result is output; Wherein, in the soil water balance equation, the soil is divided into a root layer and a non-root layer; The soil water balance equation at the root layer is expressed as: In the formula, The soil moisture content in the root layer of the next day, in cm 3 cm -3 , that is, per cm 3 The water content of soil, the same below; The actual root depth of the crop on the next day, in cm; is the soil moisture content in the root layer on that day, in cm 3 cm -3 ; The actual root depth of the crop on that day, in cm; Predicted rainfall for the next day in cm; is the soil moisture content in the non-root layer on that day, in cm 3 cm -3 ; is the canopy interception for the next day, in cm; is the runoff of the next day, in cm; is the actual evapotranspiration of crops, in cm; is the root layer leakage, in cm; The soil water balance equation of the non-root layer is expressed as: in, The non-root layer soil moisture content of the next day, in cm 3 cm -3 ; is the maximum root depth, in cm; is the soil moisture content in the non-root layer on that day, in cm 3 cm -3 ; is the deep leakage, in cm; The processes involved in the soil water balance equation include: simulation of root depth, canopy interception and surface runoff, evapotranspiration and infiltration; ① The root depth is simulated by a sinusoidal function. The current root depth is related to the relative growth time of the current root and the maximum root depth, expressed as: In the formula, is the current growth day; is the total growing days, and is the crop parameter: ②The calculation formula for canopy interception is: In the formula, is the canopy interception, a is the empirical coefficient, and the value of crops is 0.0025; is the leaf area index; is the soil coverage; To predict rainfall; The calculation formula for surface runoff is: In the formula, is the surface runoff, is the maximum possible infiltration, in cm; is the runoff index; ③ The calculation formula for crop potential evapotranspiration is: in, is the crop potential evapotranspiration, in cm; is the crop coefficient; is the crop reference evapotranspiration, in cm, derived from meteorological data; use calculate: and They are =0 and The crop coefficient at maximum, It is an empirical parameter with a reference range of 0.5-1; Potential evaporation of soil and crop potential evapotranspiration Depend on calculate: in, is the soil potential evaporation, in cm; is the crop potential transpiration, in cm; Actual soil evaporation The calculation is as follows: in, It is an empirical parameter and is related to soil texture; Actual transpiration The calculation is as follows: in, is the crop water absorption stress threshold, in cm 3 cm -3 ; is the moisture content at the wilting point, in cm 3 cm -3 ; is the field water holding capacity, in cm 3 cm -3 ; and is the crop coefficient value, and the value of each crop is based on the FAO recommended value; The actual evapotranspiration is calculated as follows: in, is the actual evapotranspiration, in cm; ④ The amount of leakage from the root layer to the non-root layer is calculated as: After the root leakage is calculated, the total water volume in the non-root layer is calculated according to the soil water balance equation of the non-root layer. If the total water volume is greater than the field water holding capacity, the part exceeding the field water holding capacity will seep into the deep layer. At this time, the total water volume in the non-root layer is .

2. The method according to claim 1, characterized in that The calculation formula of the crop soil moisture deficit index is: In the formula, Indicates The crop soil water deficit index of the day, Indicates The actual evaporation per day, Indicates Daily potential evaporation.

3. The method according to claim 2, characterized in that The calculation formula for the cumulative crop soil moisture deficit index for a period of time in the future is: In the formula, is the cumulative crop soil moisture deficit index for the next m days, , , , , …are weight coefficients, which add up to 1.

4. The method according to claim 3, characterized in that The calculation formula of the crop soil moisture deficit anomaly index is: In the formula, It represents the crop soil moisture deficit anomaly index. represents the cumulative crop soil water deficit index, Represents the average value of crop soil water deficit index.

5. A drought early warning system for crops in rain-fed areas during the entire growth period, characterized in that: It comprises a processing module, and the processing module is used to execute the drought early warning method for the whole growth period of crops in rain-fed areas as described in any one of claims 1 to 4.

6. The system according to claim 5, characterized in that: include: Big data server, used to store data required for early warning and historical data; A model operation server, used to store preset algorithms and models, and perform corresponding calculations using data obtained from the big data server; The interface server is used to deploy service interfaces, receive all web requests, and manage requests in a unified manner; The mobile APP is used to obtain the data to be displayed through the interface server.

Images