Method for quantitatively inverting precipitation space-time distribution based on soil isotope model

Abstract

The invention discloses a method for quantitatively inverting rainfall spatial and temporal distribution based on a soil isotope model. The method comprises the following steps: (1) experiment layout and isotope determination: positioning and collecting samples in a research area and performing isotope determination; (2) time scale determination: according to measured soil isotope concentration data and an isotope settlement model, calculating 10Be isotope residence time, and comparing the 10Be isotope residence time with a 14C dating result; (3) constructing a 10Be isotope-precipitation model: constructing a quantitative relation between the 10Be isotope concentration and the precipitation according to the measured soil isotope concentration data and precipitation data; and (4) rainfall spatial and temporal distribution inversion: based on the soil 10Be isotope concentration and the 10Be isotope-precipitation relationship at different time scales, inverting precipitation spatial distribution at different time scales. According to the method, the spatial difference characteristics and rules of regional rainfall distribution can be effectively disclosed, and the time and space coverage and precision of regional historical rainfall inversion are comprehensively improved.

Description

Technical Field

[0001] The present invention relates to the interdisciplinary field of hydrometeorology and isotope geochemistry, and in particular to a method for quantitatively inverting the spatiotemporal distribution of precipitation based on a soil isotope model. Background Art

[0002] Based on δ 2 H, δ 18 O, δ 13 C. 10 Numerous studies have used isotope inversions of precipitation at various timescales using Be isotopes, but most are based on isotope profiles from media such as glaciers, lakes, loess sediments, tree rings, and stalagmites. These studies can only characterize precipitation variations at different timescales based on isotope data from a single location in these media, using the precipitation at that location as a proxy for spatial precipitation variation within the region where the sample is located. However, they fail to reveal patterns in precipitation distribution within the region. This is due to the fact that these media are confined to specific regions, and the distance between two identical media is often large. If a specific media is too rare within a region, it is difficult to characterize the spatial distribution of precipitation within the target region. Furthermore, because the two media are often separated by large environmental differences, direct comparison of measured isotope indices is difficult, requiring the elimination of environmental influences. This adds uncertainty to the sample and data analysis, reducing the accuracy of the results. Therefore, it is urgent to obtain isotope data from more common media, such as soil, and to use this existing data to establish relationships between isotopes and precipitation, thereby characterizing the spatial distribution of precipitation within the study area. On this basis, combined with isotope data and dating data from different depths of the soil profile, the spatial distribution patterns of regional precipitation at different time scales were inverted. By inverting the spatial distribution characteristics of precipitation at different time scales in a certain region, a basis for predicting future changes in precipitation characteristics in the study area was provided. Summary of the Invention

[0003] Purpose of the invention: The present invention proposes a method for quantitatively inverting the spatiotemporal distribution of precipitation based on a soil isotope model, providing a basis for predicting future changes in precipitation characteristics in the study area.

[0004] Technical solution: The method of quantitatively inverting the spatiotemporal distribution of precipitation based on a soil isotope model described in the present invention comprises the following steps:

[0005] (1) Experimental layout and isotope determination: sample positioning, collection and isotope determination within the study area;

[0006] (2) Determination of time scale: Considering the soil redistribution rate and soil sample isotope concentration data of the “reference profile” in the existing studies in the region, the total amount of isotopes in the soil profile at the sampling point is estimated, and then combined with 10 Be isotope precipitation model and14 C dating results, calculation 10 Be isotope retention time and compare it with 14 Comparison of C dating results;

[0007] (3) Construction 10 Be isotope-precipitation model: Based on the soil redistribution rate and the measured soil isotope concentration data in the study area, combined with precipitation data, a soil isotope model was constructed. 10 Quantitative relationship between Be isotope concentration and precipitation;

[0008] (4) Inversion of spatiotemporal dynamic distribution of precipitation: Soil-based precipitation at different time scales 10 Be isotope concentration and 10 Be isotope-precipitation relationship, inversion of precipitation spatial distribution at different time scales.

[0009] Furthermore, the implementation process of step (1) is as follows:

[0010] The selection of sample locations in the study area, soil profile samples were collected at each sampling point using a soil drill, and the profile samples were layered after collection, with each layer being 5 cm; and each layer of soil was 10 Be isotope concentration determination; sample collection should be carried out in areas with sparse vegetation and less human interference; the depth of soil profile samples at the sampling point should be kept the same.

[0011] Furthermore, the implementation process of step (2) is as follows:

[0012] 10 The retention time of Be isotopes is:

[0013]

[0014] Among them, A i is the soil layer i of the profile sample 10 Be isotope concentration; D i is the dry bulk density of the i-th layer of soil sample; m is the number of calculated soil profile layers; S is the bottom area of ​​the soil profile sample; n is the number of layers of the “reference profile”; x j is the soil redistribution rate of the jth layer of the “reference profile” in the study area; T j is the age span of the jth layer of the “reference profile”; F c for 10 flux data for the Be isotope deposition model; represents the total amount of isotopes from the 1st to the i-th layer of the soil profile, and is the total amount of isotopes in the part of the sample site where soil redistribution (erosion or accumulation) occurs;

[0015] get 10After Be retention time, combined with the sample profile 14 C dating results, compared with those based on 14 If the difference between the ages of soil layers obtained by C dating model exceeds the preset value, 14 The C dating results are used as the basis to finally determine the research time scale corresponding to the soil samples in different layers.

[0016] Furthermore, the implementation process of step (3) is as follows:

[0017] Quantified precipitation 10 Variation characteristics of Be concentration during precipitation process:

[0018]

[0019] Where C(P) is the atmospheric 10 Be isotope concentration, α1 is a constant, P is precipitation, P0 is the atmospheric 10 The critical value of precipitation at which Be isotope concentration begins to decrease;

[0020] P0=βP, then C(P) is:

[0021]

[0022] Among them, α1, β and t are fitting constants, 0<β<1;

[0023] Deposited from precipitation and stored in soil 10 The total amount of Be isotopes is expressed as:

[0024]

[0025] Among them, α2 is the fitting constant;

[0026] When the target layer of soil profile is the mth layer, the soil 10 The relationship between Be isotope concentration and precipitation is:

[0027]

[0028] Among them, A i For the topsoil 10 Be isotope concentration; P is the measured multi-year average precipitation; R is the measured multi-year average runoff; α, β, k, and τ are fitting constants.

[0029] Furthermore, the implementation process of step (4) is as follows:

[0030] Based on the soil in different spatial locations of the study area 10 Be isotope concentration data and 10The relationship between Be isotope concentration and precipitation is combined with the corresponding time scales of samples in different layers of the soil profile to calculate the time scales and corresponding annual average precipitation of the sampling points in the region, and the annual average precipitation in the corresponding period of the sample target layer is obtained:

[0031]

[0032] Among them, P (m) is the time span represented by the mth soil layer of the calculated target layer of the sampling point profile (T m -T m-1 )’s average annual precipitation; P m-1 、P m is the average annual precipitation within the time scales corresponding to the m-1th layer and the mth layer; the historical precipitation around each sampling point in different periods is obtained, and then the spatial distribution results of precipitation at different time scales in the study area are inverted through the spatial interpolation method.

[0033] A device according to the present invention includes a memory and a processor, wherein:

[0034] a memory for storing computer programs capable of running on the processor;

[0035] The processor is configured to execute the steps of the method for quantitatively inverting the spatiotemporal distribution of precipitation based on the soil isotope model when running the computer program.

[0036] The present invention provides a storage medium having a computer program stored thereon, which, when executed by at least one processor, implements the steps of the method for quantitatively inverting the spatiotemporal distribution of precipitation based on a soil isotope model as described above.

[0037] Beneficial effects: Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention inverts regional historical precipitation by measuring isotope data in widely distributed media such as soil, thereby avoiding the defects of limited spatial distribution of media, long distances between samples of the same medium, and large environmental differences; on the one hand, it improves the spatial representativeness of medium samples, and on the other hand, it reduces the uncertainty of data comparison, improves the accuracy of results, and can effectively reveal the characteristics and laws of spatial differences in regional precipitation distribution; at the same time, the relationship between isotopes and precipitation is constructed in combination with soil redistribution, and the isotope and dating data at different depths of the soil profile are combined to more realistically invert the spatial distribution laws of precipitation at different time scales, thereby comprehensively improving the temporal and spatial coverage and accuracy of regional historical precipitation inversion, and providing a scientific basis for regional hydrological and meteorological trend evolution prediction, environmental protection, and water resources management. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is an overall framework diagram of an embodiment of the present invention.

[0039] The markings in the attached figure are as follows: study area 11, sampling point 12, soil profile sample 13, soil redistribution "reference profile" 14, spatial distribution of precipitation in the study area at different periods 21. DETAILED DESCRIPTION

[0040] The present invention will be further described in detail below with reference to the accompanying drawings.

[0041] The present invention proposes a method for quantitatively inverting the spatiotemporal distribution of precipitation based on a soil isotope model, which specifically includes the following steps:

[0042] Step 1: Experimental setup and isotope determination: Sample location, collection and isotope determination within the study area.

[0043] The sample locations in the study area were selected, and soil profile samples were collected at each sampling point using a soil drill. After the profile samples were collected, they were layered, with each layer being 5 cm, and each layer of soil was 10 Be isotope concentration determination; sample collection should be carried out in areas with sparse vegetation and less human interference; the depth of soil profile samples at the sampling point should be kept the same.

[0044] like Figure 1 As shown, the study area 11 includes the selection of sample locations 12 and soil profile samples 13, and the samples are 10 Be isotope concentration determination; sample collection 12 needs to be carried out in areas with less interference from human activities, and the depth of soil profile samples 13 at each sampling point should be kept as similar as possible.

[0045] Step 2: Time scale determination: Consider the soil redistribution rate and soil sample isotope concentration data of the “reference profile”14 in the existing studies in the region, estimate the total isotope content of the soil profile at the sampling point, and then combine 10 Be isotope precipitation model and 14 C dating results, calculation 10 Be isotope retention time and compare it with 14 Comparison of C dating results.

[0046] 10 The retention time of Be isotopes is:

[0047]

[0048] Among them, A i is the soil layer i of the profile sample 10 Be isotope concentration (atoms / g); D i is the dry bulk density of the soil sample in layer i (g / cm 3 ); m is the calculated soil profile layer number; S is the bottom area of ​​the soil profile sample (cm2 ); n is the number of layers of the “reference section”; D ave is the average dry bulk density from the profile surface to the target soil layer m (g / cm 3 );x j is the soil redistribution rate (cm / year) of the jth layer of the “reference profile” in the study area. If soil erosion occurs there, this term will be positive; if soil accumulation occurs, this term will be negative. j is the age span of the jth layer of the “reference profile” (year); F c for 10 Flux data of Be isotope precipitation model (atoms / cm 2 / year).

[0049] In formula (1) represents the total amount of isotopes from the 1st to the i-th layer of the soil profile, and The total amount of isotopes in the soil redistribution (erosion or accumulation) of the sample point. The soil redistribution rate is obtained by referring to the relevant results of the "reference profile" in the existing research in the study area. 14 C isotope dating is used to determine the soil redistribution rate data for the corresponding year of the "reference profile" and thereafter, and finally calculate the time scale of the study, T m If the soil sample is not 14 C dating, it is assumed that the year corresponding to the nth layer of the “reference profile” and the subsequent period are the reference period, and the soil redistribution rate data of the corresponding period are substituted into formula (1), and the calculation result T is calculated until the year corresponding to the nth layer is compared with the calculated result T. m When they are roughly equal, it is considered that T m The time scale of the study.

[0050] In addition, the soil dry bulk density of the redistributed soil is expressed as the average dry bulk density from the surface of the sample profile to the target soil layer (the mth layer), that is, D in formula (2) ave The concatenation of formulas (1) and (2) is shown in formula (3) to obtain 10 Be retention time. If there is no corresponding 14 C dating data, the calculated time scale T m If there is a corresponding 14 C dating data, then the comparison is based on 14 If the soil ages of each layer obtained by the C dating model differ greatly (more than 50%), 14 The C dating results are used as the basis to finally determine the research time scale corresponding to the soil samples in different layers.

[0051] like Figure 1 As shown in the figure, the soil in the sampling points of the study area10 Calculation of Be isotope retention time and 14 C isotope dating and comparative verification were used to determine the final time scale for the study. 10 The Be retention time is calculated based on the measured soil 10 Be isotope concentration and soil quality 10 The total amount of Be isotopes, followed by soil redistribution characteristics, plus the soil erosion or accumulation part 10 The total amount of Be isotopes (positive or negative) is then divided by the corresponding position in the existing global sedimentation model. 10 Be deposition flux (F c ) to obtain.

[0052] Step 3: 10 Be isotope-precipitation model construction: Based on the soil redistribution rate and the measured soil isotope concentration data in the study area, combined with precipitation data, a soil Be isotope-precipitation model was constructed. 10 The quantitative relationship between Be isotope concentration and precipitation. Determining the quantitative relationship between the two requires a large amount of measured data. However, the global measured precipitation data is generally only a few decades long. Therefore, the surface soil can be used to determine the quantitative relationship between the two. 10 The measured data of Be isotope concentration were combined with the average precipitation and multi-year average runoff data measured at different locations in the study area to construct a correlation between the measured surface soil 10 Be isotope concentration and other data to establish a quantitative numerical relationship to determine the surface soil 10 The relationship between Be isotope concentration and precipitation.

[0053] First, quantify the precipitation 10 The changing characteristics of Be concentration during precipitation process. When precipitation begins, the atmospheric 10 The concentration of Be isotopes is relatively high. As the precipitation progresses, the concentration of Be isotopes in the rainwater 10 The concentration of Be isotopes is high and can last for a period of time; when the precipitation reaches a certain value, the concentration of Be isotopes in the atmosphere 10 The concentration of Be isotopes began to decrease, and then the 10 The concentration of Be isotopes also decreases; when precipitation continues to increase, the concentration of Be isotopes in the atmosphere 10 Be is exhausted, and the corresponding precipitation 10 The Be isotope concentration is extremely low. This change process conforms to the change characteristics of the inverted Sigmoid decay function, that is, the change process of the two can be described as:

[0054]

[0055] Where C(P) is the atmospheric 10 Be isotope concentration, P is precipitation, P0 is atmospheric10 The critical value of precipitation when the Be isotope concentration begins to decrease, the relationship between P and P0 can be linearly fitted based on the data in the published literature, or based on the actual measurement of multiple precipitation events, and is generally P0 = βP (0 < β < 1). 10 The relationship between Be concentration and precipitation can be expressed as:

[0056]

[0057] Among them, α1, β and t are constants, and the rest are the same as above.

[0058] However, part of the precipitation that falls to the surface usually flows into rivers in the form of runoff. 10 Be isotopes are often unable to remain in the soil, so it is necessary to remove this part of the 10 Be from precipitation 10 Be is deducted from the total amount and can be expressed as: C(P)·(PR). According to the measured multi-year average precipitation and runoff, a nonlinear fitting is performed between the two, that is, R=kP τ (k and τ are constants). Therefore, the 10 The total amount of Be isotopes can be expressed as:

[0059]

[0060] α2 is the fitting constant.

[0061] On the other hand, the measured amount of 10 The total amount of Be isotopes can be expressed as: A1·D1·5·S. On this basis, considering the soil redistribution, 10 The total amount of Be isotopes is: but:

[0062]

[0063] When the target layer of the calculated soil profile is the mth layer, then:

[0064]

[0065] Step 4: Inversion of spatiotemporal dynamic distribution of precipitation: based on soil at different time scales 10 Be isotope concentration and 10 Be isotope-precipitation relationship, inversion of precipitation spatial distribution at different time scales.

[0066] Based on the soil in different spatial locations of the study area 10 Be isotope concentration data and 10The relationship between Be isotope concentration and precipitation, combined with the corresponding time scales of samples from different layers of the soil profile, can be used to calculate the time scale corresponding to the soil of the target layer (i.e., layer m) of the sampling point profile in the region and the annual average precipitation from that period to the present through formula (8). On this basis, using the calculation results of the m layer and the m-1 layer, the annual average precipitation of the soil of the sample target layer corresponding to the period can be obtained through formula (9):

[0067]

[0068] Among them, P (m) is the time span represented by the mth soil layer of the calculated target layer of the sampling point profile (T m -T m-1 )’s average annual precipitation; P m-1 、P m is the time scale corresponding to the m-1th layer and the mth layer (respectively T m-1 and T m Therefore, the historical precipitation around each sampling point in different periods is finally obtained, and then the spatial distribution of precipitation at different time scales in the study area is inverted through spatial interpolation methods.

[0069] like Figure 1 As shown, based on soil 10 Be isotope concentration, soil redistribution rate of the "reference profile" in the study area and historical precipitation calculated from the relationship between the precipitation in the area around the corresponding sampling point, soil profile samples 10 Be isotope concentration A i According to the actual measurement, the inverted precipitation P of the soil sample in the mth layer corresponding to the period is (m) Calculate the average annual precipitation P of soil profile samples in the study area at the same time scale (m)i , the historical precipitation around each sampling point in the study area during that period can be obtained, and then spatial interpolation methods such as inverse distance weighting in the study area can be performed using software such as ArcGIS Pro to obtain the spatial distribution results of precipitation in the study area at the corresponding time scale21.

[0070] The present invention also proposes a device comprising a memory and a processor, wherein: the memory is used to store a computer program that can be run on the processor; the processor is used to execute the steps of the method for quantitatively inverting the spatiotemporal distribution of precipitation based on the soil isotope model as described above when running the computer program.

[0071] The present invention also provides a storage medium having a computer program stored thereon. When the computer program is executed by at least one processor, the steps of the method for quantitatively inverting the spatiotemporal distribution of precipitation based on a soil isotope model as described above are implemented.

[0072] According to the embodiment of the present invention, soil 10 Be isotope data were used, and the spatiotemporal dynamic characteristics of precipitation in the study area were quantitatively inverted based on the isotope and precipitation model. The results were verified through experiments. The specific results are shown in Table 1.

[0073] Table 1 Soil samples 10 Spatiotemporal dynamic distribution of Be isotope concentration and inverted precipitation

[0074]

[0075] The experimental and calculation results show that the surface soil 10 Be isotope concentrations are significantly correlated with precipitation, and samples at different depths in the soil profile 10 Be isotope concentration can be used to invert the precipitation data of the corresponding period; secondly, 10 Be isotope retention time and 14 The C dating data were used to determine the time scale corresponding to the sample. Spatial interpolation was then used to obtain the spatial distribution of precipitation in the study area at different time scales. The results of the above examples demonstrate that the present invention can quantify regional precipitation at different time periods and reveal the dynamic patterns of regional spatial distribution differences in precipitation at different time periods.

[0076] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for quantitatively inverting the spatiotemporal distribution of precipitation based on a soil isotope model, characterized in that: The following steps are involved: (1) Experimental layout and isotope determination: sample positioning, collection and isotope determination within the study area; (2) Determination of time scale: Considering the soil redistribution rate and soil sample isotope concentration data of the "reference profile" in the existing studies in the region, the total amount of isotopes in the soil profile at the sampling point is estimated, and then combined with 10 Be isotope precipitation model and 14 C dating results, calculation 10 Be isotope retention time and compare it with 14 Comparison of C dating results; (3) Construction 10 Be isotope-precipitation model: Based on the soil redistribution rate and the measured soil isotope concentration data in the study area, combined with precipitation data, a soil isotope model was constructed. 10 Quantitative relationship between Be isotope concentration and precipitation; (4) Inversion of spatiotemporal dynamic distribution of precipitation: Soil-based precipitation at different time scales 10 Be isotope concentration and 10 Be isotope-precipitation relationship, inversion of precipitation spatial distribution at different time scales.

2. The method for quantitatively inverting the spatiotemporal distribution of precipitation based on a soil isotope model according to claim 1, characterized in that: The implementation process of step (1) is as follows: The sample locations in the study area were selected, and soil profile samples were collected at each sampling point using a soil drill. After the profile samples were collected, they were layered and each layer of soil was 10 Be isotope concentration determination; sample collection should be carried out in areas with sparse vegetation and less human interference; the depth of soil profile samples at the sampling point should be kept the same.

3. The method for quantitatively inverting the spatiotemporal distribution of precipitation based on a soil isotope model according to claim 1, characterized in that: Each layer of soil is 5 cm.

4. The method for quantitatively inverting the spatiotemporal distribution of precipitation based on a soil isotope model according to claim 1, characterized in that: The implementation process of step (2) is as follows: 10 The retention time of Be isotopes is: Among them, A i is the soil layer i of the profile sample 10 Be isotope concentration; D i is the dry bulk density of the i-th layer of soil sample; m is the number of calculated soil profile layers; S is the bottom area of ​​the soil profile sample; n is the number of layers of the "reference profile"; x j is the soil redistribution rate of the jth layer of the "reference profile" in the study area; T j is the age span of the jth layer of the "reference profile"; F c for 10 flux data for the Be isotope deposition model; represents the total amount of isotopes from the 1st to the i-th layer of the soil profile, and is the total amount of isotopes in the part of the sample site where soil redistribution (erosion or accumulation) occurs; get 10 After Be retention time, combined with the sample profile 14 C dating results, compared with those based on 14 If the difference between the ages of soil layers obtained by C dating model exceeds the preset value, 14 The C dating results are used as the basis to finally determine the research time scale corresponding to the soil samples in different layers.

5. The method for quantitatively inverting the spatiotemporal distribution of precipitation based on a soil isotope model according to claim 1, characterized in that: The implementation process of step (3) is as follows: Quantified precipitation 10 Variation characteristics of Be concentration during precipitation process: Where C(P) is the atmospheric 10 Be isotope concentration, α1 is a constant, P is precipitation, P0 is the atmospheric 10 The critical value of precipitation at which Be isotope concentration begins to decrease; P0=βP, then C(P) is: Among them, α1, β and t are fitting constants, 0<β<1; Deposited from precipitation and stored in soil 10 The total amount of Be isotopes is expressed as: Among them, α2 is the fitting constant; When the target layer of soil profile is the mth layer, the soil 10 The relationship between Be isotope concentration and precipitation is: Among them, A i For the topsoil 10 Be isotope concentration; P is the measured multi-year average precipitation; R is the measured multi-year average runoff; α, β, k, and τ are fitting constants.

6. The method for quantitatively inverting the spatiotemporal distribution of precipitation based on a soil isotope model according to claim 1, characterized in that: The implementation process of step (4) is as follows: Based on the soil in different spatial locations of the study area 10 Be isotope concentration data and 10 The relationship between Be isotope concentration and precipitation is combined with the corresponding time scales of samples in different layers of the soil profile to calculate the time scales and corresponding annual average precipitation of the sampling points in the region, and the annual average precipitation in the corresponding period of the sample target layer is obtained: Among them, P (m) is the time span represented by the mth soil layer of the calculated target layer of the sampling point profile (T m -T m-1 )’s average annual precipitation; P m-1 、P m is the average annual precipitation within the time scales corresponding to the m-1th layer and the mth layer; the historical precipitation around each sampling point in different periods is obtained, and then the spatial distribution results of precipitation at different time scales in the study area are inverted through the spatial interpolation method.

7. A device, characterized in that: comprising a memory and a processor, wherein: a memory for storing computer programs capable of running on the processor; A processor is configured to execute the steps of the method for quantitatively inverting the spatiotemporal distribution of precipitation based on a soil isotope model as described in any one of claims 1 to 6 when running the computer program.

8. A storage medium, characterized in that: The storage medium stores a computer program, which, when executed by at least one processor, implements the steps of the method for quantitatively inverting the spatiotemporal distribution of precipitation based on a soil isotope model as described in any one of claims 1 to 6.

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