Hydrogeological soil pollution characteristic detection method and system

Abstract

The present application relates to the technical field of soil detection, and more particularly to a hydrogeological soil pollution characteristic detection method and system, which comprises the following steps: S1: dividing multiple sampling units reflecting different water flow behaviors and arranging sampling points; S2: synchronously collecting soil samples and water samples at each sampling point and simultaneously acquiring topographic attribute data of each sampling point; S3: calculating a hydrological activity coefficient of each sampling point based on the topographic attribute data of the sampling point; S4: calculating a proportion share to be extracted from the soil sample of each sampling point; S5: calculating a proportion share to be extracted from the water sample of each sampling point; S6: determining a total mass ratio of water and soil when a mixed slurry is prepared; S7: mixing to prepare a final sample of a water-soil mixed slurry according to the calculated water-soil shares and mixing ratio; and S8: detecting pollutants and their concentrations in the final sample. The present application can effectively improve the predictability and accuracy of the detection result of the pollution characteristics in the hydrogeological soil.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of soil detection, and particularly relates to a hydrogeological soil pollution characteristic detection method and system. BACKGROUND

[0002] Before soil pollution treatment is carried out, the pollution characteristics (such as the types of pollutants, the concentration of pollutants, etc.) of the soil need to be detected, so that a pollution treatment scheme can be formulated. Usually, the area to be treated is large, and needs to be divided into many to-be-detected areas to form a pollution distribution map, and each to-be-detected area provides a set of data as the average pollution condition of the entire to-be-detected area. When the data of each to-be-detected area is obtained, the traditional detection method has the following defects: the traditional method often sets sampling points in the to-be-detected area, and then calculates the pollution characteristics of the samples of the sampling points by a simple arithmetic mean algorithm. For hydrogeology, the key water flow movement driving the migration and accumulation of pollutants is not taken into account, which leads to the final detection result being only a fuzzy regional average concentration, without considering the accumulation state of the pollutants in the to-be-detected area under the long-term action of the water flow, and thus the predictability and accuracy of the result are poor. SUMMARY

[0003] The present application provides a hydrogeological soil pollution characteristic detection method and system, which can effectively solve the problems in the background art.

[0004] The present application provides a hydrogeological soil pollution characteristic detection method, and the steps include:

[0005] S1: based on the digital terrain and geological data of the to-be-detected area, a plurality of sampling units reflecting different water flow behaviors are divided, and sampling points are arranged at key nodes of each sampling unit;

[0006] S2: soil samples and water samples are synchronously collected at each sampling point, and terrain attribute data of each sampling point is obtained;

[0007] S3: based on the terrain attribute data of each sampling point, a hydrological activity coefficient representing the water retention capacity of the point and the contact time of the pollutants and the soil is calculated;

[0008] S4: in combination with the area weight of the sampling unit in which each sampling point is located and the corresponding hydrological activity coefficient, a proportional share to be extracted from the soil sample of each sampling point is calculated;

[0009] S5: according to the hydrological activity coefficient of each sampling point, a proportional share to be extracted from the water sample of each sampling point is calculated;

[0010] S6: according to a typical value of the soil water-holding capacity of the to-be-detected area, the total mass ratio of water and soil when preparing a mixed slurry is determined;

[0011] S7: Extracting corresponding shares from soil samples and water samples of all sampling points according to the calculated water-soil shares and mixing ratio, and then mixing to prepare a final sample of a water-soil mixture slurry;

[0012] S8: Detecting the pollutants and their concentrations in the final sample, so as to obtain the pollution characteristics of the region to be tested.

[0013] Further, in step S1, the multiple sampling units are divided and the sampling points are arranged as follows:

[0014] Determining the overall boundary of the region to be tested;

[0015] Based on the digital terrain after filling the depression of the region to be tested, the water flow direction and the flow accumulation are calculated, and the water network is extracted; then, the entire region is divided into several sub-basins based on the water network and the divide;

[0016] Within each sub-basin, the micro-topography and the land use mutation zone which are of special significance for pollution interception are identified, and are further subdivided into sampling units with more single functions;

[0017] In each unit, at least one sampling point is arranged along the dominant water flow direction or the potential water flow path.

[0018] Further, in step S2, when collecting the water sample, if there is no water body directly above the soil sample, the water body flowing into or penetrating the soil at the uphill direction or the lateral inflow direction of the soil sample is collected.

[0019] Further, in step S3, the hydrological activity coefficient is calculated as follows:

[0020] Let the topographic attribute data of the i-th sampling point include the slope βi, the soil organic matter content OMi, the clay content CLi, and the permeability grade value Ki determined according to the soil texture category;

[0021] Calculate the topographic wetness index TWIi = ln(Ai / tanβi);

[0022] Wherein, A is the upslope catchment area of the i-th sampling point;

[0023] Calculate the hydrological retention factor Hi = (TWIi / ln(Ki+1));

[0024] Calculate the soil adsorption factor Si = CLi·(OMi+1);

[0025] The hydrological activity coefficient HPIi = (Hi·Si·Pi) 1 / 3 ;

[0026] Wherein, Pi is the land use pollution load index of the i-th sampling point.

[0027] All the hydrological activity coefficients are normalized to make their range between 0 and 1, and the hydrological activity coefficient HPIi of the i-th sampling point is updated to HPI'i after normalization.

[0028] Further, in step S4, the proportion of the soil sample to be extracted from each sampling point is calculated as follows:

[0029] The soil cumulative potential index SPIi of the i-th sampling point is calculated as SPIi = Si · (1 + a · HPI'i);

[0030] Wherein, a is an adjustment coefficient;

[0031] The proportion of the soil sample to be extracted from the i-th sampling point is calculated as WSi = (Ai / Atotal) · (SPIi / ∑SPI);

[0032] Wherein, Ai is the area of the sampling unit where the i-th sampling point is located;

[0033] Atotal is the total area of the region to be measured;

[0034] ∑SPI is the sum of all SPIi.

[0035] Further, in step S5, the proportion of the water sample to be extracted from each sampling point is calculated as follows:

[0036] The potential index PLIi of the water pollution load flux of the i-th sampling point is calculated as PLIi = TWIi · Pi · Hi;

[0037] The proportion of the water sample to be extracted from the i-th sampling point is calculated as WWi = PLIi / ∑PLI;

[0038] Wherein, ∑PLI is the sum of all PLIi.

[0039] Further, in step S6, the typical value of the soil water holding capacity of the region to be measured is calculated as follows:

[0040] Select 3-5 representative soil samples with different textures in the region to be measured, and let them stand until the gravity water stops flowing out. Measure the soil moisture content at this time and take the average value as the typical value of the soil water holding capacity of the region to be measured.

[0041] Further, in step S7, the soil sample and the water sample are mixed and stirred or mixed uniformly to form a uniform slurry as the final sample.

[0042] Further, in step S7, when preparing the final sample, the weighing of all soil samples is completed one by one in the order of sampling point numbers, and then the weighing of all water samples is completed one by one.

[0043] The application further provides a hydrogeological soil pollution characteristic detection system, comprising a storage and a processor, the storage is used for storing one or more program instructions; the processor is used for running the one or more program instructions, and is used for executing the steps of the hydrogeological soil pollution characteristic detection method.

[0044] The technical scheme can realize the following technical effects:

[0045] The method can reflect the process that the pollutants are transported under the action of water flow and absorbed by soil, calculate the contribution weight of the water and soil samples at each sampling point in the final mixture, and then physically mix a simulation sample according to the weight to simulate and predict the state of the soil formed in the to-be-detected region under the long-term influence of water flow. Finally, only one mixed sample needs to be detected, so that the evaluation conclusion of the overall condition of the to-be-detected region can be obtained. The method can effectively improve the detection efficiency and the predictability and accuracy of the detection result of the pollution characteristic of the to-be-detected region. BRIEF DESCRIPTION OF DRAWINGS

[0046] In order to more clearly illustrate the technical schemes in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments described in the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0047] Figure 1 The figure is a flowchart of the hydrogeological soil pollution characteristic detection method. DETAILED DESCRIPTION

[0048] The technical schemes in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, not all embodiments.

[0049] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0050] The present application relates to a hydrogeological soil pollution characteristic detection method, which comprises the following steps: Figure 1As shown, a total of S1-S8 steps are included, through which a multi-factor index system reflecting water flow movement, soil retention capacity and pollution input intensity is constructed, each factor is quantified as a weight coefficient with clear physical meaning, and the proportion of water and soil samples extracted from each sampling point for physical mixing is accurately guided, so as to prepare a predictive mixed sample capable of simulating the comprehensive state of soil pollution after a long-term complex process, thereby facilitating the design of subsequent treatment schemes. The specific contents of each step are as follows:

[0051] S1: Based on the digital terrain and geological data of the region to be tested, a plurality of sampling units reflecting different water flow behaviors are divided, and the water flow behavior mainly refers to the flow direction of the water flow in the sampling unit. In a sampling unit, the flow trend of the water flow should form a straight line as much as possible to form a sampling frame with clear hydrological process interpretation. After sampling points are arranged at key nodes of each sampling unit, each sampling point can represent a specific hydrological function (such as rapid runoff, slow infiltration, and pollution collection), thereby providing a true physical basis for subsequent weighted calculation.

[0052] S2: Collect samples at each sampling point, and simultaneously collect soil samples and water samples at each sampling point; there is a large possibility of difference between the digital terrain and geological data and the actual local terrain, so in order to ensure that the data has a true physical basis in subsequent calculation, the actual terrain attribute data of each sampling point needs to be obtained at the time of sampling.

[0053] S3: Based on the terrain attribute data of each sampling point, a hydrological activity coefficient representing the water retention capacity of the point and the contact time of pollutants and soil is calculated. The hydrological activity coefficient is a quantitative index representing the accumulation potential of pollutants at the point, and the coefficient can quantify the influence of the water dynamic process on pollution.

[0054] S4: Combine the area weight of the sampling unit where each sampling point is located and the corresponding hydrological activity coefficient to calculate the proportion of soil samples from each sampling point that should be extracted. This step can simulate the contribution of soil at different landforms to the overall pollution of the region after a long-term hydrological process. The soil in the accumulation area with strong hydrological activity has a greater contribution to the final mixed pollution, so it occupies a larger proportion in the preparation of the final mixed sample.

[0055] S5: According to the hydrological activity coefficient of each sampling point, the proportion of water samples from each sampling point that should be extracted is calculated. This step can simulate the contribution of water flow from different paths to soil pollution after a long-term hydrological process. Water flowing to the accumulation area has a higher probability of carrying pollutants being intercepted in the soil, so it occupies a larger proportion in the preparation of the final mixed sample.

[0056] S6: According to the typical value of the soil water holding capacity of the area to be tested, the total mass ratio of water and soil is determined when preparing the mixed slurry, so that the final sample prepared by mixing simulates the equilibrium state of the soil under natural wetting conditions, ensuring that the distribution of pollutants between the water phase and the solid phase is closer to the true value, to ensure the credibility of the detection value.

[0057] S7: According to the calculated water and soil shares and mixing ratio, the corresponding shares are extracted from the soil samples and water samples collected from all sampling points, and then a final sample of a water-soil mixed slurry is prepared by mixing, which is the soil state presented by the area to be tested after a long hydrological process.

[0058] S8: Detecting the pollutants and their concentrations in the final sample can obtain the pollution characteristics of the area to be tested.

[0059] Preferably in step S1, the multiple sampling units and sampling points are specifically:

[0060] S1.1: The entire area requiring pollution control is first divided into multiple areas to be tested, each of which is designed to have only a single water flow, and the hydrological systems of different areas to be tested are independent of each other, so as to determine the overall boundary of each area to be tested. This method is mainly used for detecting the overall soil pollution characteristics of an area to be tested;

[0061] S1.2: After determining the overall boundary of the area to be tested, obtain the digital terrain (DEM) after filling the depression of the area to be tested. The DEM after filling the depression is a digital terrain without depression after hydrological analysis preprocessing, which can eliminate the closed depression in the digital terrain to ensure the continuity of the water flow simulation. Based on the digital terrain after filling the depression, the water flow direction and the flow accumulation in the area to be tested are calculated, and the water network is extracted. Then, the entire area is divided into several sub-basins based on the water network and the divide, which can mainly reflect the different functions of the corresponding terrain in the transportation of pollution in the hydrological system. Typical sub-basin types include:

[0062] Runoff source area: water and initial migration of pollutants;

[0063] Runoff transmission area: fast channel for pollutants;

[0064] Runoff collection area: easy deposition and accumulation of pollutants.

[0065] S1.3: Within each sub-basin, identify micro-topography (such as depressions, slope feet, floodplains) and land use mutation zones (such as farmland-forest boundaries, downstream of residential areas) that have special significance for pollution interception, capture the positions where the pollutant migration flux or properties change significantly due to mutations in local areas, and further subdivide them into sampling units with more single functions.

[0066] S1.4: In each unit, at least one sampling point is arranged along the direction of the dominant water flow or the potential water flow path.

[0067] Preferably in step S2, when collecting the water body sample, if there is no water body directly above the soil sample, collect the water body flowing into or infiltrating the soil in the upslope direction or lateral inflow direction of the soil sample.

[0068] When collecting the soil sample, at the soil sampling point, excavate the profile or use the undisturbed soil sampler according to the specification to collect the undisturbed soil sample of the specified depth (such as 0-20 cm plough layer), and seal it in an inert container for low-temperature preservation.

[0069] When collecting the water body sample, first arrange the device, and collect the water body at the water sample collection point after hydrological events such as precipitation or irrigation. Ensure that the water sample collection time matches the soil sampling time to reflect the state under the same hydrological conditions.

[0070] When obtaining the actual topographic attribute data of each sampling point, the side of the geological compass (with inclinometer function) or smartphone (with calibrated slope measurement APP) is tightly attached to the representative undisturbed flat ground surface near the sampling point (within about 1 meter), ensuring that the instrument is stable, and the slope value (unit: degree or percentage) is directly read after the reading is stable. Measure 2-3 times in different directions (parallel and perpendicular to the contour line) at the same sampling point, and take the average value as the slope of the point. Soil organic matter content and clay content can be quickly measured using portable detection instruments. Soil texture can be measured by hand feeling method or simple sedimentation method.

[0071] The operation process of the hand feeling method is as follows:

[0072] Take a small amount (about the size of a peanut) of fresh soil and rub it with your fingers. There will be the following corresponding relationship between soil texture and hand feeling:

[0073] Sand: feels rough, cannot be rubbed into a strip or ball, and is easy to scatter;

[0074] Loam: feels smooth, can be rubbed into a thin strip, but is easy to break;

[0075] Clay: feels slippery, can be rubbed into a thin long strip and is not easy to break.

[0076] The operation process of the simple sedimentation method is as follows:

[0077] Take a transparent water bottle, fill it with soil sample to about 1 / 3 of its volume, add water to fill it, tighten the cap, shake vigorously, and let it stand. After standing for about 1 minute, observe the settling thickness of the coarsest sand particles at the bottom. After standing for 1 hour, observe the settling thickness of the silt particles in the middle and the turbidity of the water in the upper part. After standing for 24 hours, observe the final settling thickness of the finest clay particles at the top. Based on the relative thickness ratio of each layer, refer to the simplified soil texture triangulation card to determine the texture category.

[0078] Preferably, in step S3, the calculation of the hydrological activity coefficient is specifically as follows:

[0079] S3.1: The topographic attribute data of the i-th sampling point includes slope βi, soil organic matter content OMi, clay content CLi, and permeability grade value Ki determined according to soil texture category. Generally, the relationship between soil texture and Ki is: sandy soil is 3, loam is 2, and clay is 1. If a simple settlement method is used, the sand / clay ratio can be roughly estimated for fine-tuning: if it is determined to be sandy loam, Ki can be 2.5; if it is clay loam, Ki can be 1.5.

[0080] S3.2: Calculate the topographic humidity index TWIi=ln(Ai / tanβi);

[0081] Where A is the uphill catchment area of ​​the i-th sampling point;

[0082] TWIi comprehensively quantifies the amount of water received from the uphill slope at a given point (catchment area) and the rate of water infiltration and drainage (slope), enabling it to predict soil moisture and surface / groundwater flow at that sampling point.

[0083] S3.3: Calculate the hydrological retention factor Hi=(TWIi / ln(Ki+1));

[0084] In the formula, the larger the numerator TWI, the more water or moisture is collected at that point; the larger the denominator ln(Ki+1), the better the soil permeability and the faster the drainage. Therefore, a high Hi value indicates that the sampling point collects more water and drains relatively slowly, and the stronger the retention capacity of the water body and the pollutants within it.

[0085] S3.4: Calculate the soil adsorption factor Si = CLi·(OMi+1);

[0086] Clay particles and organic matter in soil are the main sites for soil adsorption of pollutants. In the formula, the higher the content of clay particles and organic matter, the higher the value of Si, indicating that the sampling point at this location has a stronger ability to absorb pollutants.

[0087] S3.5: Calculate the pollution input pressure factor Pi, where Pi represents the land use pollution load index of the i-th sampling point, mainly representing the potential pollution input pressure from human activities on the uphill slope.

[0088] S3.6: Calculate the hydrological activity factor HPIi=(Hi·Si·Pi) 1 / 3 ;

[0089] wherein Pi is the land use pollution load index of the i-th sampling point;

[0090] This formula uses the geometric mean method to integrate the three factors to reflect the mutual correlation between the factors. The higher the value, the stronger the hydrological retention capacity, the higher the soil adsorption capacity, and the greater the external pollution input pressure, indicating that the sampling point is a high-risk point for pollution accumulation.

[0091] S3.7: Normalize all calculated hydrological activity factors to make their ranges between 0 and 1, which is convenient for subsequent calculation. The hydrological activity factor HPIi of the i-th sampling point is updated to HPI'i after normalization, and the calculation method is:

[0092] HPI'i=(HPIi-HPImin) / (HPImax-HPImin);

[0093] wherein HPImax and HPImin are the maximum and minimum values of all HPIi, respectively.

[0094] Preferably in step S4, the proportion of soil samples to be extracted from each sampling point is calculated as follows:

[0095] S4.1: Calculate the soil accumulation potential index SPIi of the i-th sampling point, SPIi=Si·(1+α·HPI'i);

[0096] wherein α is an adjustment coefficient, 0<α≤1, for example, 0.5, used to control the strength of the influence of the hydrological activity factor HPI'i on the final soil accumulation potential;

[0097] The soil pollution accumulation potential of each sampling point is related to the basic adsorption capacity determined by the texture and organic matter of the soil, as well as the hydrological activity intensity. The soil accumulation potential index SPIi can quantify this relationship. The higher the SPIi value, the easier it is for the soil at the sampling point to accumulate pollution.

[0098] S4.2: Calculate the proportion of soil samples to be extracted from the i-th sampling point, WSi=(Ai / Atotal)·(SPIi / ΣSPI);

[0099] wherein Ai is the area of the sampling unit where the i-th sampling point is located;

[0100] Atotal is the total area of the area to be measured;

[0101] ΣSPI is the sum of all SPIi;

[0102] In the above formula for calculating the share, the calculation takes into account the macrospatial representativeness (unit area weight), the inherent property difference of the soil (Si), and the enhanced effect of hydrological and pollution input processes on accumulation (SPIi), so that the soil taken from a point with weak hydrological activity but strong soil adsorption (such as forest soil with rich organic matter) can also obtain a reasonable share.

[0103] Preferably in step S5, the proportion of the water sample from each sampling point that should be extracted is specifically calculated as:

[0104] S5.1: Since the flow to the i-th sampling point is proportional to its catchment flow, pollution concentration, and retention efficiency at the point, the potential index PLIi of the water pollution load flux of the i-th sampling point can be calculated as PLIi = TWIi · Pi · Hi;

[0105] The size of PLIi represents the size of the potential pollution load carried by the water flow through the sampling point and possibly entering the soil at the point and downstream due to retention.

[0106] S5.2: The proportion of the water sample from the i-th sampling point that should be extracted is calculated as WWi = PLIi / ∑PLI;

[0107] Where ∑PLI is the sum of all PLIi;

[0108] Since the mixing share of the water sample is determined by the proportion of the potential pollution load of each point flow, through the above formula, the water from large-area catchment, high-pollution land use types, downhill direction, and easy retention can occupy a dominant share in the mixed water sample, and the water source characteristics of the dominant regional soil pollution input can be more accurately simulated.

[0109] Preferably in step S6, the typical value of the soil water holding capacity of the area to be measured is specifically calculated as:

[0110] Select 3-5 representative soil samples with different textures in the area to be measured, take about 200 grams of each sample, let it freely drain under non-evaporation conditions, and measure the soil water content when the gravity water stops flowing out, and take the average value as the typical value of the soil water holding capacity of the area to be measured.

[0111] Preferably in step S7, after mixing the soil sample and the water sample, use a mechanical stirrer or manually stir thoroughly to mix the water and soil completely to form a homogeneous slurry as the final sample. The stirring time needs to be long enough to ensure the uniformity of each part of the final sample.

[0112] In step S7, when making the final sample, first complete the weighing of all soil samples one by one in order of sampling point number, and then complete the weighing of all water samples one by one to avoid cross and confusion.

[0113] The present application also relates to a hydrogeological soil pollution characteristic detection system, comprising a storage and a processor, the storage is used for storing one or more program instructions; the processor is used for running one or more program instructions, for executing the steps of the hydrogeological soil pollution characteristic detection method as described above.

[0114] Although the present application has been described in connection with specific embodiments thereof, it will be evident that many modifications and changes can be made thereto without departing from the spirit and scope of the application. Accordingly, it is intended to cover all modifications, alterations, combinations, or equivalents falling within the scope of the application. Obviously, many modifications and variations of this application are possible in light of its teachings. It is intended that the scope of the application encompass these and all other such modifications and equivalents.

Claims

1. A method for detecting hydrogeological soil pollution characteristics, characterized in that the steps include... include: S1: Based on the digital topography and geological data of the area to be measured, multiple sampling units reflecting different water flow behaviors are divided, and sampling points are set up at key nodes in each sampling unit. S2: Simultaneously collect soil and water samples at each sampling point, and obtain terrain attribute data for each sampling point. S3: Based on the topographic attribute data of each sampling point, calculate a hydrological activity coefficient that represents the water retention capacity and the contact time between pollutants and soil at that point; S4: Calculate the proportion to be extracted from the soil sample at each sampling point by combining the area weight of the sampling unit where each sampling point is located and its corresponding hydrological activity coefficient. S5: Calculate the proportion to be extracted from the water sample at each sampling point based on the hydrological activity coefficient at each sampling point; S6: Determine the total mass ratio of water and soil when preparing the mixed slurry based on the typical value of soil water holding capacity in the area to be tested; S7: According to the calculated water and soil share and mixing ratio, collect soil samples and water samples from all sampling points, extract the corresponding share, and then mix them to prepare a final sample of a water and soil mixed slurry. S8: By detecting the pollutants and their concentrations in the final sample, the pollution characteristics of the area to be tested can be obtained; In step S3, the calculation of the hydrological activity coefficient is specifically as follows: The topographic attribute data of the i-th sampling point includes slope βi, soil organic matter content OMi, clay content CLi, and permeability grade value Ki determined according to soil texture category; Calculate the topographic humidity index TWIi = ln(Ai / tanβi); Where A is the uphill catchment area of ​​the i-th sampling point; Calculate the hydrological retention factor Hi = (TWIi / ln(Ki+1)); Calculate the soil adsorption factor Si = CLi·(OMi+1); Hydrological activity coefficient HPii = (Hi·Si·Pi) 1 / 3 ; Where Pi is the land use pollution load index of the i-th sampling point; All the calculated hydrological activity coefficients are normalized so that they are all within the range of 0 to 1. The hydrological activity coefficient HPii of the i-th sampling point is updated to HPii'i after normalization. In step S4, the specific calculation of the proportion to be extracted from the soil sample at each sampling point is as follows: Calculate the soil accumulation potential index SPII for the i-th sampling point: SPII = Si·(1+α·HPI'i); Where α is the adjustment coefficient; Calculate the proportion of soil sample to be extracted from the i-th sampling point, WSi = (Ai / Atotal)·(SPIi / ΣSPI); Where Ai is the area of ​​the sampling unit where the i-th sampling point is located; Atotal represents the total area of ​​the region to be measured. ΣSPI is the sum of all SPII; In step S5, the specific calculation of the proportion to be extracted from the water sample at each sampling point is as follows: Calculate the potential index PLIi of the water pollution load flux at the i-th sampling point: PLIi = TWIi·Pi·Hi; Calculate the proportion of water sample to be extracted at the i-th sampling point: WWi = PLIi / ΣPLI; Where ΣPLI is the sum of all PLIi; In step S6, the typical value of soil water holding capacity in the area to be tested is calculated as follows: Select 3 to 5 representative soil samples with different textures in the area to be tested, let them stand and drain until the gravity water stops flowing out, measure the soil moisture content at this time, and take the average value as the typical value of soil water holding capacity in the area to be tested.

2. The method for detecting hydrogeological soil pollution characteristics according to claim 1, characterized in that, In step S1, dividing the sample into multiple sampling units and setting up sampling points specifically involves: Determine the overall boundary of the area to be measured; Based on the digital topography of the area to be tested after filling depressions, the direction of water flow and the cumulative amount of runoff are calculated, and the water network is extracted; then, the entire area is divided into several sub-basins by the water network and the watershed. Within each sub-basin, identify micro-topography and land use abrupt change zones that are of particular significance for pollution interception, and further subdivide them into sampling units with more specific functions. Within each unit, at least one sampling point is deployed along the dominant water flow direction or potential water flow path.

3. The method for detecting hydrogeological soil pollution characteristics according to claim 1, characterized in that, In step S2, when collecting water samples, if there is no water directly above the soil sample, the water that is about to flow into or infiltrate the soil is collected from the uphill direction or the side direction of the incoming water.

4. The method for detecting hydrogeological soil pollution characteristics according to claim 1, characterized in that, In step S7, the soil sample and the water sample are mixed and stirred or blended to form a uniform slurry as the final sample.

5. The method for detecting hydrogeological soil pollution characteristics according to claim 4, characterized in that, In step S7, when preparing the final sample, all soil samples are weighed one by one according to the sampling point number order, and then all water samples are weighed one by one.

6. A hydrogeological soil pollution characteristic detection system, characterized in that, It includes a storage device and a processor, the storage device being used to store one or more program instructions; the processor being used to run one or more program instructions to perform the steps of the hydrogeological soil pollution characteristic detection method as described in any one of claims 1 to 5.

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