Underground water quality multi-index monitoring system under influence of mine water reinjection and evaluation method

Abstract

The invention provides an underground water quality multi-index monitoring system and an evaluation method under the influence of mine water reinjection, the system takes a reinjection well as a circle center and a borehole diameter influence range of the reinjection well as a radius, a plurality of observation wells are configured in the borehole diameter influence range, and multi-index water quality sensors are arranged in the observation wells; the multi-index water quality sensor regularly transmits underground water quality indexes to the control center through the data transmitter; the control center comprises a groundwater quality comprehensive evaluation model, the comprehensive score of each groundwater sample is calculated through the groundwater quality comprehensive evaluation model, and the comprehensive water quality of groundwater under the influence of mine water reinjection is quantitatively evaluated. According to the underground water multi-index monitoring system provided by the invention, the water quality detection sensor is configured aiming at indexes of underground water change possibly caused by reinjection of highly-mineralized mine water, so that multi-index simultaneous online real-time monitoring is realized. The monitoring system can obtain the underground water quality index in the hypersalinity mine water reinjection range in real time, and provides powerful support for underground water quality evaluation.

Description

Technical Field

[0001] The invention belongs to the technical field of mine water reinjection, relates to groundwater quality monitoring, and specifically relates to a multi-index monitoring system and an evaluation method for groundwater quality under the influence of mine water reinjection. Background Art

[0002] Due to the dual influence of arid-semi-arid climate and sedimentary geological action, mining areas in the west generally face the problem of high mineralization of mine water. High mineralization refers to TDS (Total dissolved solids, TDS) greater than 1000mg / L. At present, the high-mineralization mine water is lifted to the ground for centralized treatment, which faces the problems of large water volume and high treatment cost. Reinjecting it into deep aquifers for further storage has become a new idea to solve the problem of high-mineralization mine water treatment and utilization.

[0003] Although high-mineralized mine water is simply treated before reinjection and the water quality meets the reinjection requirements, reinjection will still cause changes in the water quality of deep and even shallow groundwater. The main reasons are summarized as follows:

[0004] First, there is an obvious difference in water quality between mine water injection water and deep groundwater. During the injection process, the two types of water mix, causing changes in the water quality of the deep groundwater.

[0005] Second, during the reinjection process, the temperature, pH, and dissolved oxygen content change, disrupting the hydrogeochemical balance of the original aquifer, causing new water-rock interactions, causing mineral dissolution and release, and changing the water quality of deep groundwater.

[0006] Third, groundwater is in a state of dynamic change and circulation. Deep groundwater can replenish shallow groundwater through faults or fissures, causing changes in the water quality of shallow groundwater. At present, there is no evidence to determine whether the water quality of highly mineralized mine water changes after long-term reinjection, how to monitor it, and the extent of the change in water quality.

[0007] Based on the above reasons, affected by the long-term reinjection of high-mineralized mine water, before the mine water is reinjected, it is necessary to conduct a water quality background investigation on the surrounding groundwater sampling and analysis; and configure a certain number of monitoring wells near the reinjection wells, deploy multi-parameter water quality sensors and build an online groundwater quality monitoring system to monitor the groundwater quality; based on a large amount of monitoring data, conduct a comprehensive evaluation of the groundwater quality, compare it with the data before the mine water is reinjected, and analyze the impact of the long-term reinjection of high-mineralized mine water on the groundwater quality. Summary of the invention

[0008] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a multi-index monitoring system and evaluation method for groundwater quality under the influence of mine water reinjection, so as to solve the technical problem that the groundwater quality detection and evaluation system in the prior art needs to be further improved.

[0009] In order to solve the above technical problems, the present invention adopts the following technical solutions to achieve the above problems:

[0010] A multi-index monitoring system for groundwater quality under the influence of mine water reinjection, the system takes the reinjection well as the center of the circle and the well diameter influence range of the reinjection well as the radius, configures multiple observation wells within the well diameter influence range, and arranges multi-index water quality sensors in the observation wells.

[0011] The multi-index water quality sensor includes a TDS sensor, a pH sensor, a sodium ion sensor, a chloride ion sensor, a fluoride ion sensor and a sulfate ion sensor.

[0012] The present invention also has the following technical features:

[0013] Preferably, the mine water is high-mineralization mine water, and high-mineralization mine water refers to mine water with a TDS greater than or equal to 1000 mg / L.

[0014] Preferably, the number of observation wells is 5 to 6.

[0015] The present invention also protects a method for evaluating groundwater quality under the influence of mine water reinjection, which method adopts the multi-index monitoring system for groundwater quality under the influence of mine water reinjection as described above.

[0016] Specifically, the multi-indicator water quality sensor regularly transmits groundwater quality indicators to the control center via a data transmitter; the control center includes a groundwater quality comprehensive evaluation model, which calculates the comprehensive score of each groundwater sample through the groundwater quality comprehensive evaluation model to quantitatively evaluate the comprehensive water quality of groundwater under the influence of mine water reinjection.

[0017] Specifically, the method for constructing the comprehensive evaluation model of groundwater quality comprises the following steps:

[0018] Step 1: According to the groundwater quality indicators, the original data matrix X of the groundwater quality indicators is established, and the unified matrix Y is calculated according to the original data matrix.

[0019] Step 2: According to the unified matrix Y of groundwater quality indicators obtained in step 1, the information value of groundwater quality indicators is quantitatively analyzed, and the information weights v of groundwater quality indicators are calculated respectively. j .

[0020] Step three: quantify the grading standards for each water quality indicator based on the limit values ​​of water quality indicators in the groundwater quality standard GB / T14848-2017.

[0021] Step 4: According to the information weight v of the water quality index obtained in step 2 j The groundwater quality comprehensive evaluation model is constructed based on the classification standard obtained in step 3. The groundwater quality comprehensive evaluation model is:

[0022]

[0023] Where:

[0024] EWQI represents the comprehensive water quality index of groundwater under the influence of mine water reinjection.

[0025] Compared with the prior art, the present invention has the following technical effects:

[0026] (I) The present invention provides a groundwater multi-index monitoring system, which is equipped with water quality detection sensors for the indicators of groundwater changes that may be caused by the reinjection of high-mineralization mine water, and realizes simultaneous online real-time monitoring of multiple indicators. This monitoring system can obtain groundwater quality indicators within the scope of high-mineralization mine water reinjection in real time, providing strong support for groundwater quality evaluation.

[0027] (II) Based on the groundwater quality indicators provided by the groundwater quality multi-indicator monitoring system, the present invention has invented a comprehensive groundwater quality evaluation method based on the entropy theory and the weight distribution principle. The monitored water quality information is objectively converted into a comprehensive index, thereby realizing the quantitative evaluation of water quality changes under the influence of high-mineralization mine water reinjection.

[0028] The specific contents of the present invention are further described in detail below in conjunction with the embodiments. DETAILED DESCRIPTION

[0029] It should be noted that, unless otherwise specified, all components, devices and methods in the present invention are components, devices and methods known in the prior art.

[0030] The typical characteristics of high-mineralized mine water in the western mining area are high concentrations of conventional ions such as calcium, sodium, magnesium, and sulfate, and fluorine, iron, manganese, etc. Although the high-mineralized mine water was treated before reinjection to meet the groundwater quality standards and reinjection standards, the original water chemical balance was broken during the reinjection process. Under the dual influence of water quality mixing and water-rock interaction, the groundwater quality of the reinjection layer changed. In view of the dynamic recharge relationship between the reinjection aquifer and the Quaternary aquifer, the groundwater quality of the shallow Quaternary aquifer may change under the influence of long-term reinjection. Therefore, understanding the changes in groundwater quality under the influence of long-term reinjection of high-mineralization is of great significance to the management of mine water reinjection and the utilization of groundwater resources.

[0031] In accordance with the above technical scheme, specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent changes made on the basis of the technical scheme of this application fall within the protection scope of the present invention.

[0032] Embodiment 1:

[0033] This embodiment provides a multi-indicator monitoring system for groundwater quality under the influence of mine water reinjection. The system takes the reinjection well as the center and the well diameter influence range of the reinjection well as the radius. Multiple observation wells are configured within the well diameter influence range, and multi-indicator water quality sensors are arranged in the observation wells.

[0034] As a preferred solution of this embodiment, the mine water is high-mineralization mine water, and high-mineralization mine water refers to mine water with a TDS greater than or equal to 1000 mg / L.

[0035] Specifically, in this embodiment, the Bulutai Coal Mine is located in Ordos City, Inner Mongolia Autonomous Region, and is administratively affiliated to Wulanmulun Town, Yijinhuoluo Banner, Ordos City. The geographical coordinates are 109°49′49″~110°05′11″ east longitude and 39°21′43″~39°30′53″ north latitude. The mine field is 22.1 km long from east to west and 17.0 km wide from north to south, with a total area of ​​192.632 km 2 . The terrain in the well field is complex, with gullies and valleys, which is a typical Liangmao terrain. The terrain is higher along the Liangmao part from Shigetai to Azhen Town, Yijinhuoluo Banner, and then becomes lower to the northeast and southwest. The main aquifers in the study area are divided from top to bottom into Quaternary loose rock pore water, Tertiary Pliocene semi-cemented rock pore water, Cretaceous Zhidan Group clastic rock pore fissure water, Jurassic clastic rock pore fissure water, and the water-richness is poor. The TDS of mine water is greater than 1000mg / L, but the cost of desalination treatment is high, so it is chosen to inject mine water into the deep aquifer.

[0036] As a preferred solution of this embodiment, the multi-index water quality sensor includes a TDS sensor, a pH sensor, a chloride ion sensor, a fluoride ion sensor and a sulfate ion sensor.

[0037] Specifically, in this embodiment, mine water samples were collected from the roof aquifer, surface drainage ditch, return air tunnel, central water tank, surface lifting station and other locations in the Buertai shaft, and the contents of conventional ions and fluoride ions were tested in the laboratory. The test results are shown in Table 1.

[0038] Table 1 Water quality test and analysis results

[0039] Sampling location pH TDS F- Ca Mg Na Cl <![CDATA[SO4 2- ]]> <![CDATA[HCO3 - ]]> Top water 7.54 1264 2.42 9.39 2.5 582.21 369 157 938.36 Ground drain 7.91 604 2.4 7.32 11.2 403.2 41.563 131.06 669.657 Return air lane 7.21 612 2.59 9.32 13.4 344.5 40.055 328.69 68.035 Central water tank 7.78 770 2.22 11.23 16.2 401.2 47.417 132.05 3.903 Ground lifting station 7.35 650 2.09 12.36 17.3 367.4 44.493 131.26 197.187

[0040] According to the groundwater quality standard GB / T14848-2017, pH, TDS, Cl - 、SO4 2- 、F - Five indicators exceeded the third category limit of the underground quality standard. Long-term reinjection may cause the indicators in groundwater to exceed the standard. Therefore, the screening monitoring indicators are pH, TDS, Cl - 、SO4 2- 、F - It is a long-term monitoring indicator. - The four indicators cannot be monitored online due to sensor limitations, and they have a certain impact on water quality. Therefore, they need to be synchronized with the monitoring data, sampled every three months, and analyzed with the help of indoor tests.

[0041] As a preferred solution of this embodiment, the method for determining the influence radius R of the wellbore influence range of the reinjection well is:

[0042]

[0043] Where:

[0044] S w Indicates the water level drop in the reinjection well;

[0045] Q represents the flow rate of mine water reinjection;

[0046] K represents the permeability coefficient of the reinjection layer;

[0047] M represents the thickness of the reinjection layer;

[0048] r w represents the radius of the reinjection well;

[0049] R represents the influence radius of the wellbore diameter influence range of the reinjection well.

[0050] Specifically, in this embodiment, according to the position of the reinjection well, according to the parameters of the reinjection well (Table 2), and the above formula, the well diameter influence range of mine water reinjection is determined. With the reinjection well as the center of the circle and the well diameter influence range of 48m as the radius, an observation well is arranged near the reinjection well, and groundwater quality monitoring equipment is arranged in the observation well for real-time monitoring of groundwater quality.

[0051] Table 2 Reinjection well parameters

[0052] Q M K <![CDATA[r w ]]> <![CDATA[S w ]]> <![CDATA[10 2 ]]> 50 <![CDATA[10 -2 ]]> 10m 50m

[0053] According to the above formula, the influence radius R of the wellbore influence range of the reinjection well is:

[0054]

[0055] R=48m

[0056] As a preferred solution of this embodiment, there are 5 to 6 observation wells.

[0057] Embodiment 2:

[0058] The present invention also protects a method for evaluating groundwater quality under the influence of mine water reinjection, which adopts the multi-index monitoring system for groundwater quality under the influence of mine water reinjection given in Example 1.

[0059] The multi-index water quality sensor regularly transmits groundwater quality indicators to the control center through the data transmitter; the control center includes a groundwater quality comprehensive evaluation model, which calculates the comprehensive score of each groundwater sample and quantitatively evaluates the comprehensive water quality of groundwater under the influence of mine water reinjection.

[0060] Specifically in this embodiment, because the depth of the reinjection layer is 1390m, while the burial depth of the Quaternary aquifer is within the range of 30m-100m, which is a large difference, considering the impact of water quality evolution, the monitoring frequency is determined to be 3 months, and data is exported every 3 months for comprehensive water quality evaluation.

[0061] Specifically, in this embodiment, after the high-mineralization mine water injection wells and groundwater quality monitoring wells were laid out, the first batch of shallow Quaternary water quality monitoring data was obtained, and the data summary is shown in Table 3.

[0062] Table 3 Groundwater quality monitoring data

[0063] serial number pH <![CDATA[F - ]]> TDS <![CDATA[Ca 2+ ]]> <![CDATA[Mg 2+ ]]> <![CDATA[Na + ]]> <![CDATA[Cl - ]]> <![CDATA[SO4 2- ]]> <![CDATA[HCO3 - ]]> 1 8.24 3.71 1954.66 28.85 1.76 562.05 268.8 58.45 1027.26 2 8.26 6.75 1724.83 7.69 1.1 509.53 206.8 32.21 965.36 3 7.87 3.71 920 28.52 1.37 363.6 242 48 616.92 4 8.5 6.75 2348 3.18 4.73 159 369 21.2 1524 5 8.26 7.17 205.46 9.39 2.5 582.21 369 157 938.36 6 7.54 2.42 1264 7.32 11.2 403.2 41.563 131.06 669.657 7 7.91 2.4 604 9.32 13.4 344.5 40.055 128.69 68.035 8 7.21 2.59 612 11.23 16.2 401.2 47.417 132.05 3.903 9 7.78 2.22 770 12.36 17.3 367.4 44.493 131.26 197.187 10 10.1 8.65 2647.73 51.05 12.75 810.51 369 691.22 1524

[0064] Specifically, in this embodiment, taking the first water sample as an example, the method for constructing a comprehensive evaluation model for groundwater quality includes the following steps:

[0065] Step 1: According to the groundwater quality indicators, the original data matrix X of the groundwater quality indicators is established, and the unified matrix Y is calculated according to the original data matrix, so as to finally achieve the purpose of unifying the groundwater quality indicators.

[0066] The original data matrix X is:

[0067]

[0068] Where:

[0069] i represents the serial number of the groundwater sample, i = 1, 2, …, m;

[0070] j represents the serial number of the groundwater quality index type, j = 1, 2, ... n;

[0071] m represents the number of groundwater samples;

[0072] n represents the total number of groundwater quality indicator types.

[0073] The unified matrix Y is:

[0074]

[0075]

[0076] Where:

[0077] (x ij ) min represents the minimum value of the jth groundwater quality index of the ith sample;

[0078] (x ij ) max It represents the maximum value of the j-th groundwater quality index of the ith sample.

[0079] Specifically, in this step, the original data matrix of the first water sample is X = [8.24, 3.71, 1954.66, 28.85,

[0080] 1.76, 562.05, 268.8, 58.45 1027.26]. And so on, the original data matrix X of all water samples can be obtained.

[0081] The maximum and minimum values ​​in the sample set of the first water sample are shown in Table 4:

[0082] Table 4 Maximum and minimum values ​​in the sample set

[0083]

[0084]

[0085] According to yij The calculation formula is unified:

[0086]

[0087]

[0088]

[0089]

[0090]

[0091]

[0092]

[0093]

[0094]

[0095] The unified matrix Y of the first water sample obtained in this embodiment is [0.4, 0.414, 0.717, 0.348, 0.075, 0.693, 0.726, 0.085, 0.673]. Similarly, the unified matrix Y of all water samples can be obtained.

[0096] Step 2: Based on the unified matrix Y of groundwater quality indicators obtained in step 1, the information value of groundwater quality indicators is quantitatively analyzed based on entropy theory, and the information weights v of groundwater quality indicators are calculated respectively. j .

[0097] Information weight of water quality index v j The calculation method is:

[0098]

[0099]

[0100]

[0101] Where:

[0102] v j represents the information weight of the jth groundwater quality index of all samples;

[0103] u j represents the information value of the jth groundwater quality index of all samples;

[0104] P ij Represents the value of the j-th groundwater quality index of the ith sample.

[0105] The values ​​of various groundwater quality indicators of the first water sample obtained in this embodiment are P ij The corresponding matrix is ​​[0.027, 0.032, 0.077, 0.028, 0.005, 0.060, 0.060, 0.011, 0.072]. By analogy, we can get the values ​​of various groundwater quality indicators of all water samples P ij The corresponding matrix.

[0106] The information values ​​u of various groundwater quality indicators of the first water sample obtained in this embodiment j The corresponding matrix is ​​[0.945, 0.864, 0.886, 0.880, 0.892, 0.891, 0.840, 0.868, 0.876]. By analogy, we can get the information value u of various groundwater quality indicators of all water samples. j The corresponding matrix.

[0107] The information weights v of various groundwater quality indicators of the first water sample obtained in this embodiment j The corresponding matrix is ​​[0.0513, 0.1289, 0.1078, 0.1137, 0.1023, 0.1028, 0.1514, 0.125, 0.1168]. By analogy, we can get the information weights v of various groundwater quality indicators of all water samples. j The corresponding matrix.

[0108] Step three: quantify the grading standards for each water quality indicator based on the limit values ​​of water quality indicators in the groundwater quality standard GB / T14848-2017.

[0109] Specifically, in this embodiment, the three types of limit values ​​in the groundwater quality standard are shown in Table 5.

[0110] Table 5 Limits of 3 indicators of groundwater quality

[0111] parameter pH <![CDATA[F - ]]> TDS <![CDATA[Ca 2+ ]]> <![CDATA[Mg 2+ ]]> <![CDATA[Na + ]]> <![CDATA[Cl - ]]> <![CDATA[SO4 2- ]]> <![CDATA[HCO3 - ]]> Limits 6.5-8.5 1.0 1000 \ \ 200 250 250 \

[0112] The grading standards are:

[0113]

[0114] Where:

[0115] q j It represents the standard scale for the classification of the j-th groundwater quality index;

[0116] C j It is the chemical concentration corresponding to the jth groundwater quality index;

[0117] S jIt represents the allowable limit given in the groundwater quality standard GB / T14848-2017 corresponding to the j-th groundwater quality index.

[0118] Specifically, in this embodiment, the standard scale for the classification of groundwater quality indicators of the first water sample is calculated respectively:

[0119]

[0120]

[0121]

[0122]

[0123]

[0124]

[0125] Get the standard scale q of groundwater quality index classification of the first water sample j The corresponding quantitative scoring matrix is ​​[82.66, 371, 1.954, 0, 0, 281.025, 107.52, 23.38, 0]. By analogy, the standard scale q for the classification of groundwater quality indicators of all water samples can be obtained. j The corresponding quantitative scoring matrix

[0126] Step 4: According to the information weight v of the water quality index obtained in step 2 j The comprehensive evaluation model of groundwater quality is constructed based on the classification standard obtained in step 3. The comprehensive evaluation model of groundwater quality is:

[0127]

[0128] Where: EWQI represents the comprehensive water quality index of groundwater under the influence of mine water reinjection.

[0129] Specifically in this embodiment, the comprehensive water quality index of groundwater under the influence of mine water reinjection of the first water sample is:

[0130]

[0131] The quality levels of groundwater samples were divided into five categories: 0-25 (Class I water), 25-50 (Class II water), 50-100 (Class III water), 100-150 (Class IV water), and >150 (Class V water), so the first water sample was classified as Class IV water.

[0132] By analogy, the comprehensive water quality index of groundwater under the influence of mine water reinjection of all water samples can be obtained. Referring to the above detailed calculation steps, a comprehensive evaluation is conducted on the ten groundwater samples obtained by monitoring, and the evaluation results are shown in Table 6.

[0133] Table 6 Comprehensive evaluation results of groundwater quality

[0134] serial number Comprehensive score of groundwater quality Groundwater quality classification 1 121.22 Ⅳ 2 150.21 Ⅴ 3 96.45 Ⅲ 4 149.02 Ⅳ 5 159.05 Ⅴ 6 76.46 Ⅲ 7 67.12 Ⅲ 8 70.79 Ⅲ 9 67.72 Ⅲ 10 61.61 Ⅲ

Claims

1. A multi-index monitoring system for groundwater quality under the influence of mine water reinjection, characterized in that: The system takes the reinjection well as the center of the circle and the well diameter influence range of the reinjection well as the radius. Multiple observation wells are configured within the well diameter influence range, and multi-indicator water quality sensors are arranged in the observation wells. The multi-index water quality sensor includes a TDS sensor, a pH sensor, a sodium ion sensor, a chloride ion sensor, a fluoride ion sensor and a sulfate ion sensor.

2. The multi-index monitoring system for groundwater quality under the influence of mine water reinjection as claimed in claim 1 is characterized in that: The method for determining the influence radius R of the wellbore influence range of the reinjection well is: Where: S w Indicates the water level drop in the reinjection well; Q represents the flow rate of mine water reinjection; K represents the permeability coefficient of the reinjection layer; M represents the thickness of the reinjection layer; r w represents the radius of the reinjection well; R represents the influence radius of the wellbore diameter influence range of the reinjection well.

3. The multi-index monitoring system for groundwater quality under the influence of mine water reinjection as claimed in claim 1 is characterized in that: The mine water is high-mineralization mine water, and high-mineralization mine water refers to mine water with a TDS greater than or equal to 1000 mg / L.

4. The multi-index monitoring system for groundwater quality under the influence of mine water reinjection as claimed in claim 1 is characterized in that: The observation wells described are 5 to 6 observation wells.

5. A method for evaluating groundwater quality under the influence of mine water reinjection, the method adopting the multi-index monitoring system for groundwater quality under the influence of mine water reinjection as claimed in any one of claims 1 to 4.

6. The method for evaluating groundwater quality under the influence of mine water reinjection as claimed in claim 5, characterized in that: The multi-index water quality sensor regularly transmits groundwater quality indicators to the control center via a data transmitter; the control center includes a groundwater quality comprehensive evaluation model, which calculates the comprehensive score of each groundwater sample and quantitatively evaluates the comprehensive water quality of groundwater under the influence of mine water reinjection.

7. The method for evaluating groundwater quality under the influence of mine water reinjection as claimed in claim 6, characterized in that: The method for constructing the comprehensive evaluation model of groundwater quality comprises the following steps: Step 1: According to the groundwater quality index, an original data matrix X of the groundwater quality index is established, and a unified matrix Y is calculated according to the original data matrix; Step 2: According to the unified matrix Y of groundwater quality indicators obtained in step 1, the information value of groundwater quality indicators is quantitatively analyzed, and the information weights v of groundwater quality indicators are calculated respectively. j ; Step 3: quantify the classification standard of each water quality indicator according to the limit values ​​of water quality indicators in the groundwater quality standard GB / T14848-2017; Step 4: According to the information weight v of the water quality index obtained in step 2 j The groundwater quality comprehensive evaluation model is constructed based on the classification standard obtained in step 3. The groundwater quality comprehensive evaluation model is: Where: EWQI represents the comprehensive water quality index of groundwater under the influence of mine water reinjection.

8. The method for evaluating groundwater quality under the influence of mine water reinjection as claimed in claim 7, characterized in that: In step 1, the original data matrix X is: Where: i represents the serial number of the groundwater sample, i = 1, 2, …, m; j represents the serial number of the groundwater quality index type, j = 1, 2, ... n; m represents the number of groundwater samples; n represents the total number of groundwater quality indicator types; In step 1, the unified matrix Y is: Where: (x ij ) min represents the minimum value of the jth groundwater quality index of the ith sample; 9x ij ) max It represents the maximum value of the j-th groundwater quality index of the ith sample.

9. The method for evaluating groundwater quality under the influence of mine water reinjection as claimed in claim 8, characterized in that: In step 2, the information weight v of the water quality index is j The calculation method is: Where: v j represents the information weight of the jth groundwater quality index of all samples; u j represents the information value of the jth groundwater quality index of all samples; P ij Represents the j-th groundwater quality index value of the ith sample.

10. The method for evaluating groundwater quality under the influence of mine water reinjection as claimed in claim 8, characterized in that: In step 3, the grading standard is: Where: q j It represents the standard scale for the classification of the j-th groundwater quality index; C j It is the chemical concentration corresponding to the jth groundwater quality index; S j It represents the allowable limit given in the groundwater quality standard GB / T14848-2017 corresponding to the j-th groundwater quality index.

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