A climate-based soil water balance simulation calculation method

Abstract

The present invention discloses a soil water balance simulation calculation method based on climate, including: S1, constructing a complementary relationship model of actual evapotranspiration about climate, and determining the actual evapotranspiration under different climate modes; S2, calculating the crop water requirement of the area to be studied based on the actual evapotranspiration; S3, constructing a soil water balance model based on the water cycle law and crop water requirement of the area to be studied, and then determining the soil water balance change. The present invention fully considers the impact of climate on soil water, constructs a complementary relationship model of actual evapotranspiration about climate, obtains actual evapotranspiration based on the model, determines the actual water requirement of the study area, and constructs a soil water balance model in combination with other influencing parameters, thereby realizing the simulation calculation of soil water balance and realizing real-time monitoring of multi-layer soil moisture content, which is conducive to strengthening regional water resources management, rationally utilizing precipitation resources and soil water resources, and alleviating water resource scarcity.

Description

Technical Field

[0001] The invention belongs to the field of ecohydrological science and technology, and in particular relates to a soil water balance simulation calculation based on climate. Background Art

[0002] Soil moisture is an important component of the water cycle and an important indicator parameter in the fields of hydrology, meteorology and agricultural science research. The content and movement of soil water profoundly affect the transformation process of soil internal substances and play an important role in agricultural production, ecological environment construction and protection through transpiration. In the Global Soil Moisture Program, soil water has been discussed and studied as a special entity and has become one of the important focuses of global change research. Therefore, in-depth research on the mechanism of soil moisture changes and clarifying the changes in soil water balance processes are of great practical significance for strengthening regional water resources management, rationally utilizing precipitation resources, and alleviating water scarcity.

[0003] Soil water refers to the water that can be separated from the soil at 105 degrees Celsius under one atmosphere of pressure. Soil water is the material basis for plant growth and survival. It not only affects the yield of forests, field crops, vegetables and fruit trees, but also affects the distribution of plants on the land surface.

[0004] Traditional soil moisture monitoring methods include empirical statistics (calculating soil moisture from meteorological and topographic factors through empirical formulas and mathematical statistics), micrometeorological methods (energy balance, aerodynamic energy balance, and aerodynamic vorticity correlation, etc.), soil water movement law analysis methods (soil water balance calculation, zero flux surface, lysimetry, and soil hydrodynamics), etc. However, although the soil moisture monitoring methods in the prior art can simulate the variation of thick soil moisture, it is difficult to meet the requirements of continuous soil moisture monitoring at a regional scale. Therefore, the traditional soil moisture monitoring methods have certain limitations and cannot meet the spatial and dynamic requirements of multi-layer soil moisture simulation related to climate. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, the present invention provides a climate-based soil water balance simulation calculation method to solve the above-mentioned problems.

[0006] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention is: a soil water balance simulation calculation method based on climate, comprising:

[0007] S1. Construct a complementary relationship model of actual evapotranspiration with respect to climate and determine the actual evapotranspiration under different climate models;

[0008] S2. Calculate the crop water requirement of the area to be studied based on actual evapotranspiration;

[0009] S3. Based on the water cycle laws and crop water requirements of the study area, a soil water balance model is constructed to determine the change in soil water balance.

[0010] Furthermore, the climate models in step S1 include SSP1-2.6, SSP2-4.5, SSP5-8.5, SSP1-1.9, SSP4-4.3, SSP5-3.4OS and SSP3-7.0.

[0011] Furthermore, the actual evapotranspiration complementary relationship model in step S1 is:

[0012]

[0013] Among them, climate has an impact on E a The contribution rate of change is:

[0014] P cc =ΔE a,cc / (|ΔE a,lc |+|ΔE a,cc |)

[0015] In the formula, E a is the actual evapotranspiration, E w is the evapotranspiration in a humid environment, E p is the potential evapotranspiration, Δ(T e ) is the saturated water vapor pressure slope at the sleeping temperature, T e is the water surface temperature, γ is the psychrometric constant, T a is the underlying surface temperature, e a is the water surface temperature T e The actual water vapor pressure under * is the saturated water vapor pressure, ΔE a,cc E in the climate model a The change in the magnitude of ΔE a,lc The change of underlying surface to E a , Δ is the slope of the saturated water vapor pressure curve.

[0016] Furthermore, the calculation formula of the potential evapotranspiration is:

[0017]

[0018] The calculation formula of evapotranspiration in the humid environment is:

[0019]

[0020] In the formula, R n is the net radiation, G is the soil heat flux, T is the average soil temperature, U 2 is the average wind speed, r is the average temperature coefficient value, and λ is the latent heat of vaporization.

[0021] Furthermore, the crop water requirement in step S2 refers to the sum of the water required for the specific crops to grow in a large area of ​​farmland with good soil moisture conditions and no pests and diseases;

[0022] The influencing factors of the crop water requirement include reference crop evapotranspiration and crop coefficient.

[0023] Furthermore, the calculation formula for the crop water requirement is:

[0024] ET c =f(v)K c ×ET o

[0025] Where f(v) is the crop coefficient influence function, K c is the crop coefficient, ET o is the reference crop evapotranspiration;

[0026] in, A and B are the initial stages of crop growth. 1 and mid-stage 3 The corresponding crop coefficient influencing factors, t is time, v is growth rate, b and c are the growth stages f during crop growth. 2 and the withering stage 4 Crop coefficient influence constant; ET o =(1-β)E a , β is the control factor of crop water requirement.

[0027] Furthermore, in step S3, the influencing factors of the soil water balance model include crop water demand, groundwater directly used by crops, rainfall infiltration recharge, field infiltration recharge, canal infiltration recharge, groundwater evaporation and surface water evaporation.

[0028] Furthermore, the crops directly utilize groundwater G i (Z) is:

[0029]

[0030] In the formula, G i (Z) is the amount of groundwater directly used by the i-th crop during the entire growth period when the water depth is Z. i,t is the groundwater depth of the tth month in the growth period of the i-th crop, t is the initial month of the growth period of the i-th crop, m is the last month of the growth period of the i-th crop, k is the index, a n,t is the coefficient;

[0031] The rainfall infiltration recharge W p for:

[0032] W p =F·P

[0033] In the formula, F is the calculation unit area, P is the rainfall;

[0034] The field infiltration recharge W a for:

[0035] W a =α·I

[0036] In the formula, α is the field infiltration recharge, and I is the amount of irrigation water entering the field;

[0037] The canal system infiltration recharge W c for:

[0038] W c =δ·S c

[0039] Where δ is the canal leakage recharge coefficient, S c loss of water transport for the canal system;

[0040] The diving evaporation E g for:

[0041] E g =C(Z)·F·E 0

[0042] Where, C(Z) is the evaporation of water, E 0 is the evaporation depth of the water surface;

[0043] The surface water evaporation E a for:

[0044] E a =θ·E 0 ·S a

[0045] Where, is the surface water evaporation coefficient, S a It is the surface water area of ​​the field.

[0046] Furthermore, the soil water balance change in step S3 includes the replenishment amount and the extraction amount; wherein the replenishment amount W h The expression is:

[0047]

[0048] The mining volume W y The expression is:

[0049]

[0050] Where i and j are the ordinal numbers of the calculation unit and the calculation crop, and η is the water utilization coefficient.

[0051] The beneficial effects of the present invention are:

[0052] (1) The present invention proposes a soil water balance simulation calculation method based on climate, which can maintain a certain soil water balance simulation calculation accuracy and realize the spatialization and dynamicization of multi-layer soil moisture simulation;

[0053] (2) The present invention fully considers the impact of climate on soil water, constructs a complementary relationship model of actual evapotranspiration related to climate, and obtains actual evapotranspiration based on the model, determines the actual crop water requirement in the study area, and constructs a soil water balance model based on the direct use of groundwater by crops, rainfall infiltration recharge, field infiltration recharge, canal infiltration recharge, groundwater evaporation and surface water evaporation, thereby realizing the simulation calculation of soil water balance and the real-time monitoring of multi-layer soil moisture content, which is conducive to strengthening regional water resources management, rationally utilizing precipitation resources and soil water resources, and alleviating water shortage. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 This is a flow chart of the climate-based soil water balance simulation calculation method provided by the present invention. DETAILED DESCRIPTION

[0055] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0056] Embodiment 1:

[0057] The embodiment of the present invention provides a soil water balance simulation calculation method based on climate, such as Figure 1 As shown, including:

[0058] S1. Construct a complementary relationship model of actual evapotranspiration with respect to climate and determine the actual evapotranspiration under different climate models;

[0059] S2. Calculate the crop water requirement of the area to be studied based on actual evapotranspiration;

[0060] S3. Based on the water cycle laws and crop water requirements of the study area, a soil water balance model is constructed to determine the change in soil water balance.

[0061] The climate model in step S1 of the embodiment of the present invention includes SSP1-2.6, SSP2-4.5, SSP5-8.5, SSP1-1.9, SSP4-4.3, SSP5-3.4OS and SSP3-7.0. A climate model is a theoretical system for studying climate. Currently, the models for studying climate can be divided into four categories: energy balance model, radiation convection model, atmospheric circulation model and statistical dynamic model.

[0062] The actual evapotranspiration complementary relationship model in step S1 of the embodiment of the present invention is:

[0063]

[0064] Among them, climate has an impact on E a The contribution rate of change is:

[0065] P cc =ΔE a,cc / (|ΔE a,lc |+|ΔE a,cc |)

[0066] In the formula, E a is the actual evapotranspiration, E w is the evapotranspiration in a humid environment, E p is the potential evapotranspiration, Δ(T e ) is the saturated water vapor pressure slope at the sleeping temperature, T e is the water surface temperature, γ is the psychrometric constant, T a is the underlying surface temperature, e a is the water surface temperature T e The actual water vapor pressure under * is the saturated water vapor pressure, ΔE a,cc E in the climate model a The change in the magnitude of ΔE a,lc The change of underlying surface to E a , Δ is the slope of the saturated water vapor pressure curve.

[0067] In the embodiment of the present invention, the PM method is used to calculate the potential evapotranspiration. The PM method has a good hydrophysical basis and is suitable for calculating the potential evapotranspiration of different types of Qionghu Lake. The calculation formula is:

[0068]

[0069] The calculation formula of evaporation in a humid environment in the embodiment of the present invention is:

[0070]

[0071] In the formula, R nis the net radiation, G is the soil heat flux, T is the average soil temperature, U 2 is the average wind speed, r is the average temperature coefficient value, and λ is the latent heat of vaporization.

[0072] In the above formula, the slope of the saturated water vapor pressure curve can be obtained from the average temperature, and the average temperature, saturated water vapor pressure and actual water vapor pressure are functions of the minimum and maximum temperatures. In order to improve the efficiency of the sensitivity analysis of climate elements, the average of the daily maximum and minimum temperatures is used instead of the daily average temperature in this embodiment, and the influence of factors such as radiation, relative humidity and wind speed are considered. Finally, the key climate elements of the sensitivity analysis are determined to be five factors: daily radiation, daily maximum temperature, daily minimum temperature, relative humidity and wind speed.

[0073] In the embodiment of the present invention, E is calculated p Sensitivity coefficient to climate factors vi The formula is:

[0074]

[0075] In the formula, se vi is the ith meteorological factor (V i ) sensitivity coefficient. The larger the sensitivity coefficient, the greater the p The greater the impact of the meteorological factor, the greater the sensitivity coefficient is. The sensitivity coefficient is the slope of the tangent of the sensitivity curve. When the sensitivity curve is linear, the sensitivity coefficient represents the effect of any interval change of the meteorological factor on E p When the sensitivity curve is nonlinear, the accuracy of the sensitivity coefficient depends on the change step of the selected meteorological factor. The smaller the change of the meteorological factor, the higher the accuracy of the sensitivity coefficient. Based on the sensitivity analysis, E p The response degree to climate change is different, which is conducive to the influence of regional climate factors on E p dominant analysis.

[0076] In step S2 of the embodiment of the present invention, the crop water requirement refers to the sum of water required for growth in a large area of ​​farmland with good soil moisture conditions and no pests and diseases; the influencing factors of the crop water requirement include reference crop evapotranspiration and crop coefficient.

[0077] The calculation formula of the crop water requirement in step S2 of the embodiment of the present invention is:

[0078] ET c =f(v)K c ×ET o

[0079] Where f(v) is the crop coefficient influence function, K c is the crop coefficient, ET o is the reference crop evapotranspiration;

[0080] in, A and B are the initial stages of crop growth. 1 and mid-stage 3 The corresponding crop coefficient influencing factors, t is time, v is growth rate, b and c are the growth stages f during crop growth. 2 and the withering stage 4 Crop coefficient influence constant; ET o =(1-β)E a , β is the crop water requirement control factor. Specifically, in the initial stage of growth, that is, from sowing to the stage when the crop coverage reaches 10%, the crop coefficient K c Take a constant. During the crop growth period, that is, when the crop coverage rate increases from 10% to about 75%, that is, when the soil surface can be effectively covered, the crop coefficient K c The value of is based on time as the independent variable and K as the dependent variable c The linear function value of the crop coefficient K is a constant in the middle and late stages of the crop, from the time when the leaves begin to turn yellow and wither until the plant reaches physiological maturity and the fruit is harvested. c The value of is based on time as the independent variable and K as the dependent variable c The linear function value of .

[0081] In step S3 of the embodiment of the present invention, the influencing factors of the soil water balance model include crop water demand, groundwater directly used by crops, rainfall infiltration recharge, field infiltration recharge, canal infiltration recharge, groundwater evaporation and surface water evaporation; wherein, the groundwater directly used by crops G i (Z) is:

[0082]

[0083] In the formula, G i (Z) is the amount of groundwater directly used by the i-th crop during the entire growth period when the water depth is Z. i,t is the groundwater depth of the tth month in the growth period of the i-th crop, t is the initial month of the growth period of the i-th crop, m is the last month of the growth period of the i-th crop, k is the index, a n,t is the coefficient;

[0084] The rainfall infiltration recharge W p for:

[0085] W p =F·P

[0086] In the formula, F is the calculation unit area, P is the rainfall;

[0087] The field infiltration recharge W a for:

[0088] W a =α·I

[0089] In the formula, α is the field infiltration recharge, and I is the amount of irrigation water entering the field;

[0090] The canal system infiltration recharge W c for:

[0091] W c =δ·S c

[0092] Where δ is the canal leakage recharge coefficient, S c loss of water transport for the canal system;

[0093] The diving evaporation E g for:

[0094] E g =C(Z)·F·E 0

[0095] Where, C(Z) is the evaporation of water, E 0 is the evaporation depth of the water surface;

[0096] The surface water evaporation E a for:

[0097] E a =θ·E 0 ·S a

[0098] Where, is the surface water evaporation coefficient, S a It is the surface water area of ​​the field.

[0099] The soil water balance change amount in step S3 of the embodiment of the present invention includes the replenishment amount and the extraction amount;

[0100] Among them, the supply amount W h The expression is:

[0101]

[0102] The mining volume W y The expression is:

[0103]

[0104] Where i and j are the ordinal numbers of the calculation unit and the calculation crop, and η is the water utilization coefficient.

[0105] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "thickness", "upper", "lower", "horizontal", "top", "bottom", "inner", "outer", "radial", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", and "third" are only used for descriptive purposes and cannot be understood as indicating or implying the relative importance or the number of implicitly specified technical features. Therefore, the features defined by "first", "second", and "third" may explicitly or implicitly include one or more of the features.

Claims

1. A soil water balance simulation calculation method based on climate, characterized in that: include: S1. Construct a complementary relationship model of actual evapotranspiration with respect to climate and determine the actual evapotranspiration under different climate models; S2. Calculate the crop water requirement of the area to be studied based on actual evapotranspiration; S3. Based on the water cycle law and crop water demand of the area to be studied, a soil water balance model is constructed to determine the change in soil water balance; The actual evapotranspiration complementary relationship model in step S1 is: Among them, climate has an impact on E a The contribution rate of change is: P cc =ΔE a,cc / (ΔE a,lc |+|ΔE a,cc |) In the formula, E a is the actual evapotranspiration, E w is the evapotranspiration in a humid environment, E p is the potential evapotranspiration, Δ(T e ) is the saturated water vapor pressure slope at the sleeping temperature, T e is the water surface temperature, γ is the psychrometric constant, T a is the underlying surface temperature, e a is the water surface temperature T e The actual water vapor pressure under * is the saturated water vapor pressure, ΔE a,cc E in the climate model a The change in the magnitude of ΔE a,lc E is the effect of underlying surface change on a The influence value of , Δ is the slope of the saturated water vapor pressure curve; The water requirement of crops in step S2 refers to the sum of water required for the growth of crops grown in large areas of farmland with good soil moisture conditions and no pests and diseases; The influencing factors of the crop water requirement include reference crop evapotranspiration and crop coefficient; In step S3, the influencing factors of the soil water balance model include crop water demand, groundwater directly used by crops, rainfall infiltration recharge, field infiltration recharge, canal infiltration recharge, groundwater evaporation and surface water evaporation.

2. The soil water balance simulation calculation method based on climate according to claim 1 is characterized in that: The climate models in step S1 include SSP1-2.6, SSP2-4.5, SSP5-8.5, SSP1-1.9, SSP4-4.3, SSP5-3.4OS and SSP3-7.

0.

3. The soil water balance simulation calculation method based on climate according to claim 1 is characterized in that: The calculation formula of potential evapotranspiration is: The calculation formula of evapotranspiration in the humid environment is: In the formula, R n is the net radiation, G is the soil heat flux, T is the average soil temperature, U2 is the average wind speed, r is the average temperature coefficient, and λ is the latent heat of vaporization.

4. The soil water balance simulation calculation method based on climate according to claim 1 is characterized in that: The calculation formula for the crop water requirement is: AND c =f(v)K c ×AND o Where f(v) is the crop coefficient influence function, K c is the crop coefficient, ET o is the reference crop evapotranspiration; in, A and B are the influencing factors of crop coefficient corresponding to the initial stage f1 and the mid-term stage f3 of crop growth, t is time, v is growth rate, b and c are the influencing constants of crop coefficient in the growth stage f2 and the withering stage f4 of crop growth process, respectively; ET o =(1-β)E a , β is the control factor of crop water requirement.

5. The soil water balance simulation calculation method based on climate according to claim 1 is characterized in that: The amount of groundwater directly used by crops G i (Z) is: In the formula, G i (Z) is the amount of groundwater directly used by the i-th crop during the entire growth period when the water depth is Z. i,t is the groundwater depth of the tth month in the growth period of the i-th crop, t is the initial month of the growth period of the i-th crop, m is the last month of the growth period of the i-th crop, k is the index, a n,t is the coefficient; The rainfall infiltration recharge W p for: W p =F·P In the formula, F is the calculation unit area, P is the rainfall; The field infiltration recharge W a for: W a =α·I In the formula, α is the field infiltration recharge, and I is the amount of irrigation water entering the field; The canal system infiltration recharge W c for: W c =δ·S c Where δ is the canal leakage recharge coefficient, S c loss of water transport for the canal system; The diving evaporation E g for: E g =C(Z) F E0 In the formula, C(Z) is the evaporation of water surface, and E0 is the evaporation depth of water surface; The surface water evaporation E l for: BY l =θ·E0·S a Where θ is the surface water evaporation coefficient, S a It is the surface water area of ​​the field.

6. The soil water balance simulation calculation method based on climate according to claim 5 is characterized in that: The soil water balance change in step S3 includes the replenishment amount and the extraction amount; Among them, the supply amount W h The expression is: The mining volume W y The expression is: Where i and j are the ordinal numbers of the calculation unit and the calculation crop, and η is the water utilization coefficient.

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