Water quality survey methods at each level

Abstract

To easily investigate the quality of groundwater flowing from a plurality of aquifers.SOLUTION: Each layer water quality investigation method for investigating the water quality of groundwater S flowing into a well W, the method comprises: a pumping step A of pumping up the ground water S at a position above a first aquifer T1 with a lifting pump 2; a water sampling step B of sampling the ground water S with a water sampling pump 3 in the pumping step A; and an investigation step C of investigating the water quality of the ground water S sampled in the water sampling step B. The investigation step includes a first analysis step of analyzing the ground water S at a position above the first aquifer T1, a second analysis step of analyzing the ground water S between the first aquifer T1 and a second aquifer T2, and a first calculation step of calculating the water quality of a first ground water T1 flowing in from the first aquifer S1 from a difference between the analysis result obtained in the first analysis step and the analysis result obtained in the second analysis step.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for investigating water quality of each layer.

Background Art

[0002] The following Patent Document 1 describes a well pumping volume investigation system capable of grasping the inflow situation of groundwater flowing into a well hole for each aquifer. The well pumping volume investigation system includes a pumping pump, a first water temperature detection means, a second water temperature detection means, and a third water temperature detection means. The first water temperature detection means detects the initial water temperature of water present at the vertical center of the first strainer portion provided in the first aquifer. The second water temperature detection means detects the water temperature at the time of pumping of water present at the upper end of the first strainer portion. The third water temperature detection means detects the water temperature at the time of pumping of water present at the upper end of the second strainer portion provided in the second aquifer.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a well provided in a ground including a plurality of aquifers, groundwater having different water qualities flows into the well from each of the plurality of aquifers. Therefore, the groundwater in the well is in a state where the groundwater from each aquifer is mixed. Therefore, it has been difficult to simply investigate the water quality of the groundwater for each aquifer.

[0005] In view of the above actual situation, the present disclosure has been devised, and the main object is to provide a method for investigating the water quality of each layer of groundwater flowing into a well, which can simply investigate the water quality of each groundwater flowing into the well.

Means for Solving the Problems

[0006] This disclosure relates to a method for investigating the water quality of each layer of groundwater flowing into a well, wherein the well is located in a ground where a plurality of aquifers are arranged vertically, the plurality of aquifers include a first aquifer located at the uppermost position and a second aquifer located below the first aquifer, the groundwater includes a first groundwater flowing in from the first aquifer and a second groundwater flowing in from the second aquifer, and comprises a pumping step of drawing up the groundwater located above the first aquifer with a pumping pump, a sampling step of collecting the groundwater with a sampling pump during the pumping step, and the sample collected in the sampling step The method for investigating the water quality of each aquifer includes an investigation step to investigate the water quality of the groundwater, the sampling step includes a first sampling step to collect groundwater at a location above the first aquifer, and a second sampling step to collect groundwater between the first aquifer and the second aquifer, the investigation step includes a first analysis step to analyze the groundwater collected in the first sampling step, a second analysis step to analyze the groundwater collected in the second sampling step, and a first calculation step to determine the water quality of the first groundwater from the difference between the first analysis result obtained in the first analysis step and the second analysis result obtained in the second analysis step. [Effects of the Invention]

[0007] The water quality investigation method for each layer disclosed herein, by adopting the above configuration, allows for the simple investigation of the water quality of each type of groundwater flowing into a well. [Brief explanation of the drawing]

[0008] [Figure 1] This is a conceptual side view showing each water quality testing apparatus used in each water quality testing method of one embodiment of the present disclosure. [Figure 2] (a) is a side view showing a pump house in which a water sampling pump is housed, and (b) is a side view showing a pump house in another embodiment. [Figure 3] This is a side view conceptually illustrating the second water sampling process. [Figure 4] This is a side view conceptually illustrating the third water sampling process. [Figure 5]This is a flowchart of the investigation process. [Figure 6] This is a side view conceptually illustrating the method for investigating the water quality of each layer in a well according to another embodiment. [Modes for carrying out the invention]

[0009] One form of implementation of this disclosure will be described below with reference to the drawings. Figure 1 is a conceptual side view showing each layer water quality investigation method (hereinafter sometimes referred to as the investigation method) of this embodiment. As shown in Figure 1, each layer water quality investigation device (hereinafter sometimes referred to as the device) 1 is used in the investigation method of this embodiment. In the investigation method of this disclosure, the water quality can be investigated for each groundwater S flowing into the well W.

[0010] The well W is located in a ground G where multiple aquifers T are arranged vertically. In this embodiment, the ground G consists of alternating aquifers T and impermeable layers H. The aquifers T have properties that allow groundwater S to flow more easily than the impermeable layers H.

[0011] In this embodiment, the aquifer T includes a first aquifer T1 located at the uppermost position and a second aquifer T2 located below the first aquifer T1. The aquifer T further includes, for example, a third aquifer T3 located below the second aquifer T2. In this embodiment, the impermeable layer H includes a first impermeable layer H1, a second impermeable layer H2, a third impermeable layer H3, and a fourth impermeable layer H4. The first impermeable layer H1 is located above and adjacent to the first aquifer T1. The second impermeable layer H2 is located between the first aquifer T1 and the second aquifer T2. The third impermeable layer H3 is located between the second aquifer T2 and the third aquifer T3. The fourth impermeable layer H4 is located below the third aquifer T3.

[0012] In this embodiment, the well W extends from the ground surface to the fourth impermeable layer H4. The inner circumferential surface of the well W is formed, for example, by a casing pipe K and a strainer pipe N for reinforcing the well W. The casing pipe K is composed of a well-known structure that has the function of preventing the inflow of soil and groundwater S into the well W, and is placed in each impermeable layer H. The strainer pipe N is composed of a well-known structure that has the function of allowing groundwater S to flow into the well W while preventing the inflow of soil, and is placed in each aquifer T. The casing pipe K and the strainer pipe N are formed of, for example, synthetic resin or metal. The well W is not particularly limited, but has a depth of 30 to 300 m and an inner diameter d of 150 to 500 mm.

[0013] The first aquifer T1 allows the first groundwater S1 to flow into the well W. The second aquifer T2 allows the second groundwater S2 to flow into the well W. The third aquifer T3 allows the third groundwater S3 to flow into the well W. The first groundwater S1 through the third groundwater S3 may have different water qualities, or they may have the same water quality.

[0014] Apparatus 1 includes a pumping pump 2 and a sampling pump 3 for pumping up groundwater S from a well W. In this embodiment, pumping pump 2 and sampling pump 3 are submersible pumps of a well-known structure that are placed in the groundwater S. Pumping pump 2 may also be placed on the surface. Apparatus 1 includes, for example, a measuring instrument of a well-known structure (not shown) for measuring the amount of groundwater S pumped up by pumping pump 2, and an analytical instrument of a well-known structure (not shown) for analyzing the water quality of groundwater S pumped up by sampling pump 3. The analytical instrument measures substances α dissolved in the groundwater S, such as nitrate nitrogen and nitrite nitrogen, ammonia nitrogen, manganese and its compounds, iron and its compounds, chromaticity, turbidity, hydrogen ion concentration (pH), oxidation-reduction potential (ORP), and residual chlorine concentration. However, substances α are not limited to these. Furthermore, the water quality of each of the groundwater samples, from the first groundwater S1 to the third groundwater S3 (including the concentration of substance α), is considered to have remained virtually unchanged over time.

[0015] The water sampling pump 3 is housed, for example, in a pump house 4. The pump house 4 is movable up and down within the well W. In this embodiment, the pump house 4 is held in place by a water lifting pipe 7 wound around a well-known winding reel 8 placed on the ground surface. In this embodiment, the water lifting pipe 7 is connected to the discharge port (not shown) of the water sampling pump 3. The water lifting pipe 7 is made of, for example, a flexible polyethylene pipe.

[0016] Figure 2(a) is a detailed longitudinal cross-sectional view of the pump house 4 of this embodiment. As shown in Figure 2(a), the pump house 4 is formed in a cylindrical shape. In this embodiment, the pump house 4 includes a house body 5 in which the opening area of ​​the cross-section decreases in a stepped manner from the central part in the vertical direction toward both ends, and a water intake pipe 6 provided at the lower end of the house body 5. The house body 5 includes, for example, a central part 5a where the water sampling pump 3 is located, a lower end part 5b to which the water intake pipe 6 is connected, and an upper end part 5c from which the water lifting pipe 7 extends. The lower end part 5b and the upper end part 5c have smaller opening areas than the central part 5a. The water sampling pump 3 pumps groundwater S taken in from the suction port of the water sampling pump 3 through the water intake pipe 6 to the surface via the water lifting pipe 7. In the central part 5a, for example, a rubber member 9 for holding the water lifting pipe 7 is provided. In this embodiment, the pump house 4 and the water intake pipe 6 are made of polyvinyl chloride.

[0017] Figure 2(b) is a longitudinal cross-sectional view of the pump house 4 in another embodiment. Components identical to those in the pump house 4 in Figure 2(a) are denoted by the same reference numerals and their descriptions may be omitted. As shown in Figure 4(b), in this embodiment, the pump house 4 includes a cylindrical house body 5 that houses the water sampling pump 3 and a water intake pipe 6 located at the lower end of the house body 5. The house body 5 in this embodiment is cylindrical with a constant vertical opening area in its cross-section. In this embodiment, the house body 5 is made of stainless steel.

[0018] Next, an investigation method using such an apparatus 1 will be described. In this investigation method, the concentration of substance α dissolved in each groundwater S is investigated. The investigation method of this embodiment includes a pumping process A, a water sampling process B, and an investigation process C. As shown in FIG. 1, the pumping process A is a process of pumping up groundwater S with a pumping pump 2. The water sampling process B is a process of collecting groundwater S with a water sampling pump 3 during the pumping process A. The investigation process C is a process of investigating the water quality of the groundwater S collected in the water sampling process B. The amount of water pumped up by the water sampling pump 3 is the amount of water required for investigating the water quality, for example, 1 to 40 L / min.

[0019] In the pumping process A, the pumping pump 2 is arranged, for example, above the first aquifer T1 and below the pumping water level that drops due to pumping. The pumping volume of the pumping pump 2 is the volume of water that all the groundwater S, in this embodiment, the first groundwater S1 to the third groundwater S3, flows into the well W through the strainer pipe N. Thereby, each of the first groundwater S1, the second groundwater S2, and the third groundwater S3 can be moved upward toward the pumping pump 2 and pumped up. Thus, in the pumping process A, the groundwater S at the height position of the first impervious layer H1 becomes the first mixed groundwater M1 in which the first groundwater S1, the second groundwater S2, and the third groundwater S3 are mixed. In other words, in the pumping process A, the pumping pump 2 pumps up the first mixed groundwater M1. Also, the groundwater S at the height position of the second impervious layer H2 becomes the second mixed groundwater M2 in which the second groundwater S2 and the third groundwater S3 are mixed. Further, the groundwater S at the height position of the third impervious layer H3 and the groundwater S at the height position of the fourth impervious layer H4 are formed only by the third groundwater S3. The pumping volume Va of such a pumping pump 2 is, for example, 100 to 4000 L / min. The pumping pump 2 pumps up substantially the same amount of water, for example, during the pumping process A.

[0020] The water extraction process B includes a first water extraction process B1 and a second water extraction process B2 (shown in FIG. 3). Further, the water extraction process B of the present embodiment includes a third water extraction process B3 (shown in FIG. 4). In the present embodiment, the first water extraction process B1, the second water extraction process B2, and the third water extraction process B3 are performed while pumping up the first mixed groundwater M1 with the pumping pump 2.

[0021] In the first water extraction process B1, groundwater S at a position above the first aquifer T1 is collected. In the present embodiment, the suction pipe 6 of the pump house 4 is arranged at the height position of the first impervious layer H1 in the first water extraction process B1. Thereby, in the first water extraction process B1 of the present embodiment, the first mixed groundwater M1 is pumped up.

[0022] FIG. 3 is a side view showing the second water extraction process B2. As shown in FIG. 3, in the second water extraction process B2, groundwater S between the first aquifer T1 and the second aquifer T2 is collected. In the present embodiment, the suction pipe 6 of the pump house 4 is arranged at the height position of the second impervious layer H2 in the second water extraction process B2. Thereby, in the second water extraction process B2 of the present embodiment, the second mixed groundwater M2 is pumped up.

[0023] FIG. 4 is a side view showing the third water extraction process B3. As shown in FIG. 4, in the third water extraction process B3, groundwater S between the second aquifer T2 and the third aquifer T3 is collected. In the present embodiment, the suction pipe 6 of the pump house 4 is arranged at the height position of the third impervious layer H3 in the third water extraction process B3. Thereby, in the third water extraction process B3 of the present embodiment, the third groundwater S3 is pumped up.

[0024] The investigation method of this embodiment includes a water flow rate measurement step (not shown) in which the inflow rate (inflow rate per unit time) V of each groundwater S1 to S3 flowing into the well W is measured. In this embodiment, each inflow rate V is calculated from the product of the vertical flow velocity v of the groundwater S in the well W and the inner diameter d (cross-sectional area) of the well W. The flow velocity v is measured, for example, with a well-known micro-velocity logger (spinner logger). As a micro-velocity logger, for example, the improved micro-velocity meter manufactured by OYO Corporation is preferred. In this embodiment, the flow velocity v is measured during the pumping process A. In other words, the water flow rate measurement step is performed, for example, together with the pumping process A, and the flow velocity v is generated by the pumping pump 2.

[0025] The flow velocity v measured in the water volume measurement process includes, for example, the first flow velocity v1 at the height of the first impermeable layer H1, the second flow velocity v2 at the height of the second impermeable layer H2, and the third flow velocity v3 at the height of the third impermeable layer H3 (shown in Figure 4). In this embodiment, the first flow velocity v1 is the flow velocity of the third groundwater S3, the second groundwater S2, and the first groundwater S1, i.e., the flow velocity of the first mixed groundwater M1. In this embodiment, the second flow velocity v2 is the flow velocity of the third groundwater S3 and the second groundwater S2, i.e., the flow velocity of the second mixed groundwater M2. In this embodiment, the third flow velocity v3 is the flow velocity of only the third groundwater S3. The inflow rate V3 of the third groundwater S3 is determined by the product K3 of the third flow velocity v3 and the inner diameter d (cross-sectional area of ​​well W) at the height of the third impermeable layer H3. The inflow rate V2 of the second groundwater S2 is the value obtained by subtracting the inflow rate V3 of the third groundwater S3 from K2, which is the product of the second flow velocity v2 and the cross-sectional area of ​​the well W at the height of the second impermeable layer H2. The inflow rate V1 of the first groundwater S1 is the value obtained by subtracting the inflow rate V2 of the second groundwater S2 and the inflow rate V3 of the third groundwater S3 from K1, which is the product of the first flow velocity v1 and the cross-sectional area of ​​the well W at the height of the first impermeable layer H1.

[0026] Here, the product K1 of the first flow velocity v1 and the cross-sectional area of ​​the first impermeable layer H1 at the specified height is the pumping rate Va of the water pump 2. However, due to measurement errors, etc., the product K1 may differ from (be smaller than) the pumping rate Va of the water pump. In this case, the inflow rate of each groundwater source S1 to S3 is the product of the ratio of the product K1 to the pumping rate Va (Va / K1) and the respective inflow rates (V1 to V3) measured and calculated by a micro-velocity logger. Note that the method for determining the respective inflow rates V of each groundwater source S1 to S3 is not limited to this configuration, and various methods may be employed. In this specification, it is assumed that the product K1 and the pumping rate Va of the water pump 2 are the same.

[0027] Next, investigation process C is performed. Figure 5 is a flowchart of investigation process C. As shown in Figure 5, investigation process C includes the first analysis process C1, the second analysis process C2, and the first calculation process C4. Furthermore, investigation process C in this embodiment also includes the third analysis process C3 and the second calculation process C5. Note that each analysis process C1, C2, and C3 may be performed before the calculation processes C4 and C5. Each analysis process C1, C2, and C3 may be performed in any order. Each calculation process C4 and C5 may also be performed in any order. In each analysis process C1, C2, and C3, the concentration of substance α dissolved in groundwater S is analyzed using the analytical instrument.

[0028] In the first analysis step C1 of this embodiment, the first mixed groundwater M1 collected in the first water sampling step B1 is analyzed to obtain the first analysis result X1. In other words, in the first analysis step C1, groundwater S, which is a mixture of the first groundwater S1, the second groundwater S2, and the third groundwater S3, is analyzed. The first analysis result X1 includes the concentration of substance α contained in the first mixed groundwater M1.

[0029] In the second analysis step C2 of this embodiment, the second mixed groundwater M2 collected in the second water sampling step B2 is analyzed to obtain the second analysis result X2. In other words, in the second analysis step C2, groundwater S, which is a mixture of the second groundwater S2 and the third groundwater S3, is analyzed. The second analysis result X2 includes the concentration of substance α contained in the second mixed groundwater M2.

[0030] In the third analysis step C3 of this embodiment, the third groundwater S3 collected in the third water sampling step B3 is analyzed to obtain the third analysis result X3. In other words, in the third analysis step C3, only the third groundwater S3 is analyzed. The third analysis result X3 of this embodiment includes the concentration (water quality) of substance α contained in the third groundwater S3.

[0031] Next, calculation steps C4 and C5 are performed. In the first calculation step C4, the water quality of the first groundwater S1 is determined from the difference between the first analysis result X1 and the second analysis result X2. In this embodiment, the first calculation step C4 calculates the mass a1 of substance α contained in the first mixed groundwater M1 (flow rate per unit time) by multiplying the concentration of substance α in the first mixed groundwater M1 (based on the first analysis result X1) by the sum of the inflow rates of each groundwater S1 to S3 (V1 + V2 + V3 = product K1). Also, the mass a2 of substance α contained in the second mixed groundwater M2 (flow rate per unit time) is calculated by multiplying the concentration of substance α in the second mixed groundwater M2 (based on the second analysis result X2) by the sum of the inflow rates of each groundwater S2 and S3 (V2 + V3 = product K2). The difference between mass a1 and mass a2 (a1 - a2) is the mass of substance α contained in the first groundwater S1. Therefore, the ratio of the difference (a1-a2) to the inflow rate V1 of the first groundwater S1 ((a1-a2) / V1) is expressed as the concentration (water quality) of substance α dissolved in the first groundwater S1.

[0032] In the second calculation step C5, the water quality of the second groundwater S2 is determined from the difference between the third analysis result X3 obtained in the third analysis step C3 and the second analysis result X2. In the second calculation step C5, the mass a3 of the substance α contained in the third groundwater S3 (flow rate per unit time) is calculated by multiplying the concentration of the substance α dissolved in the third groundwater S3 by the third analysis result X3 and the inflow rate V3 of the third groundwater S3. The difference (a2 - a3) between the mass a2 of the substance α contained in the second mixed groundwater M2 obtained in the first calculation step C4 and the mass a3 is the mass of the substance α contained in the second groundwater S2. Therefore, the ratio ((a2 - a3) / V2) between the difference (a2 - a3) and the inflow rate V2 of the second groundwater S2 is shown as the concentration (water quality) of the substance α dissolved in the second groundwater S2. Thus, with the investigation method of the present embodiment, the water quality (concentration of the substance α) of each of the groundwaters S1 to S3 can be easily investigated.

[0033] FIG. 6 is a side view for explaining an investigation method in a well W of another embodiment. The same components as those in the investigation method in the well W of the present embodiment may be denoted by the same reference numerals and their explanations may be omitted. As shown in FIG. 6, the well W of this embodiment is disposed in a ground G provided with n aquifers T (n is a natural number of 3 or more). The aquifers T of this embodiment include the (n - 2)-th aquifer T(n - 2) from the first aquifer T1 downward, the (n - 1)-th aquifer T(n - 1) from the first aquifer T1 downward, and the n-th aquifer Tn from the first aquifer T1 downward.

[0034] In this specification, an investigation method for investigating the water quality of the (n - 1)-th groundwater S(n - 1) flowing in from the (n - 1)-th aquifer T(n - 1) is described. The method for investigating the water quality of the (n - α)-th groundwater S(n - α) flowing in from the (n - α)-th aquifer T(n - α) (natural number of 1 < α < n) is the same.

[0035] This investigation method also includes a pumping step A, a water sampling step B, and an investigation step C. Further, it includes a step of obtaining the respective inflow rates Vn and V(n - 1) of the n-th groundwater Sn and the (n - 1)-th groundwater S(n - 1) flowing into the well W.

[0036] In this embodiment, the water sampling process B is also performed during the pumping process A. The water sampling process B in this embodiment includes the (n-1) water sampling process B(n-1) which samples groundwater S between the (n-2) aquifer T(n-2) and the (n-1) aquifer T(n-1), and the nth water sampling process Bn which samples groundwater S between the (n-1) aquifer T(n-1) and the nth aquifer Tn. In the (n-1) water sampling process B(n-1), groundwater S mixed with the nth groundwater Sn and the (n-1) groundwater S(n-1) is sampled. In the nth water sampling process Bn, only the nth groundwater Sn is sampled.

[0037] The investigation process includes an (n-1)th analysis process (not shown), an nth analysis process, and an (n-1)th calculation process. In the (n-1)th analysis process, groundwater S collected in the (n-1)th water sampling process B(n-1) is analyzed. In this embodiment, the (n-1)th analysis process analyzes the water quality (concentration of substance α) of groundwater S mixed with groundwater Sn and groundwater S(n-1). In the nth analysis process, the water quality (concentration of substance α) of groundwater S collected in the nth water sampling process Bn is analyzed. In this embodiment, only groundwater Sn is analyzed in the nth analysis process.

[0038] In the (n-1) calculation step, the water quality of the (n-1) groundwater S(n-1) is determined from the difference between the (n-1) analysis result obtained in the (n-1) analysis step and the n analysis result obtained in the n analysis step. In this embodiment, the (n-1) calculation step calculates the mass a(n-1) of substance α contained in the (n-1) mixed groundwater M(n-1) by multiplying the concentration of substance α in the (n-1) mixed groundwater M(n-1) based on the (n-1) analysis result by the sum of the inflow rates of each groundwater Sn and S(n-1) (Vn + V(n-1)). In addition, in the (n-1) calculation step, the mass an of substance α contained in the nth groundwater Sn (flow rate per unit time) is calculated by multiplying the concentration of substance α dissolved in the nth groundwater Sn based on the n analysis result by the inflow rate Vn of the nth groundwater Sn. The difference between mass a(n-1) and mass an (a(n-1)-an) is the mass of substance α contained in groundwater (n-1) S(n-1). Therefore, the ratio of the difference (a(n-1)-an) to the inflow rate V(n-1) of groundwater (n-1) S(n-1) ((a(n-1)-an) / V(n-1)) indicates the concentration of substance α dissolved in groundwater (n-1) S(n-1).

[0039] Although particularly preferred embodiments of this disclosure have been described in detail above, this disclosure is not limited to the illustrated embodiments and can be implemented in various modified forms.

[0040] [Note] This disclosure includes the following aspects.

[0041] [Disclosure 1] A method for investigating the water quality of groundwater flowing into a well, The aforementioned well is located in a ground where multiple aquifers are arranged vertically. The aforementioned multiple aquifers include a first aquifer located at the uppermost position and a second aquifer located below the first aquifer. The aforementioned groundwater includes first groundwater flowing in from the first aquifer and second groundwater flowing in from the second aquifer. The process includes a pumping step of drawing up the groundwater located above the first aquifer using a pumping pump, a sampling step of collecting the groundwater using a sampling pump during the pumping step, and an investigation step of investigating the water quality of the groundwater collected in the sampling step. The water sampling process includes a first water sampling process for sampling groundwater located above the first aquifer, and a second water sampling process for sampling groundwater between the first aquifer and the second aquifer. The investigation process includes a first analysis step of analyzing the groundwater collected in the first water sampling step, a second analysis step of analyzing the groundwater collected in the second water sampling step, and a first calculation step of determining the water quality of the first groundwater from the difference between the first analysis result obtained in the first analysis step and the second analysis result obtained in the second analysis step. Water quality investigation method for each layer. [Disclosure 2] The aforementioned multiple aquifers further include a third aquifer located below the second aquifer. The aforementioned groundwater further includes the third groundwater flowing in from the third aquifer. The water sampling step further includes a third water sampling step of sampling the groundwater between the second aquifer and the third aquifer, The method for investigating the water quality of each layer according to Disclosure 1, wherein the investigation step includes a third analysis step of analyzing the groundwater collected in the third water sampling step, and a second calculation step of determining the water quality of the second groundwater from the difference between the third analysis result obtained in the third analysis step and the second analysis result. [Disclosure 3] The aforementioned aquifers include the (n-2)th (n-2)th aquifer (where n is a natural number greater than or equal to 3) located downward from the first aquifer, the (n-1)th The aforementioned groundwater includes the (n-1) groundwater flowing in from the (n-1) aquifer, The water sampling process includes an (n-1) water sampling process for sampling the groundwater between the (n-2) aquifer and the (n-1) aquifer, and an nth water sampling process for sampling the groundwater between the (n-1) aquifer and the n aquifer. The method for investigating the water quality of each layer according to Disclosure 1 or 2, wherein the investigation step includes an (n-1) analysis step of analyzing the groundwater collected in the (n-1) water sampling step, an nth analysis step of analyzing the groundwater collected in the nth water sampling step, and an (n-1) calculation step of determining the water quality of the (n-1) groundwater from the difference between the (n-1) analysis result obtained in the (n) analysis step and the nth analysis result obtained in the nth analysis step. [Disclosure 4] A method for investigating the water quality of each aquifer according to any one of disclosures 1 to 3, further comprising a water volume measurement step for measuring the amount of groundwater flowing in from each of the plurality of aquifers. [Disclosure 5] The water volume measurement step is performed together with the water pumping step, in the method for investigating the water quality of each layer as described in Disclosure 4. [Disclosure 6] The method for investigating the water quality of each layer according to any one of disclosures 1 to 5, wherein the water sampling pump is housed in a pump house having a suction pipe for taking in groundwater at its lower end. [Disclosure 7] The method for investigating the water quality of each layer according to disclosure 6, wherein the pump house is held so as to be movable up and down within the well. [Explanation of symbols]

[0042] 2. Water pump 3. Water sampling pump A. Pumping process B. Water extraction process C. Investigation Process C1 1st analysis step C2 2nd analysis process C4 1st calculation step T1 1st aquifer T2 2nd aquifer S Groundwater S1 1st groundwater

Claims

1. A method for investigating the water quality of groundwater flowing into a well, The aforementioned well is located in a ground where multiple aquifers and multiple impermeable layers are arranged alternately in the upper and lower layers. The well includes a first aquifer located at the uppermost position, a second impermeable layer adjacent to the first aquifer below it, and a second aquifer adjacent to the second impermeable layer below it. The aforementioned groundwater includes first groundwater flowing in from the first aquifer and second groundwater flowing in from the second aquifer. The process includes a pumping step in which groundwater located above the first aquifer is pumped up by a pumping pump at a rate that moves groundwater flowing in from the multiple aquifers upward; a sampling step in which groundwater is collected by a sampling pump during the pumping step; and an investigation step in which the water quality of the groundwater collected in the sampling step is investigated. The water sampling process includes a first water sampling process for sampling groundwater at a location above the first aquifer, and a second water sampling process for sampling groundwater at the location of the second impermeable layer. The aforementioned investigation process is, A first analysis step involves analyzing the groundwater collected in the first water sampling step, A second analysis step involves analyzing the groundwater collected in the second water sampling step, A water volume measurement step is performed together with the pumping step and measures the amount of groundwater flowing in from each of the multiple aquifers, The process includes a first calculation step which determines the water quality of the first groundwater from the difference in the amount of substance calculated based on the first analysis result obtained in the first analysis step and the second analysis result obtained in the second analysis step and the inflow amount measured in the water volume measurement step, Water quality investigation method for each layer.

2. The well further includes a third impermeable layer below the second aquifer and adjacent to the second aquifer, and a third aquifer below the third impermeable layer and adjacent to the third impermeable layer, The aforementioned groundwater further includes the third groundwater flowing in from the third aquifer. The water sampling step further includes a third water sampling step of sampling the groundwater at the location of the third impermeable layer, The aforementioned investigation process is, A third analysis step involves analyzing the groundwater collected in the third water sampling step, A method for investigating the water quality of each layer according to claim 1, comprising: a second calculation step of determining the water quality of the second groundwater from the difference in the amount of substance calculated based on the third analysis result obtained in the third analysis step and the second analysis result and the inflow amount measured in the water volume measurement step.

3. The well includes the (n-2)th (n is a natural number of 3 or more) aquifer (n-2) below the first aquifer, the (n-1) impermeable layer below the (n-2) aquifer and adjacent to the (n-2) aquifer, the (n-1) aquifer below the (n-1) impermeable layer and adjacent to the (n-1) impermeable layer, the nth impermeable layer below the (n-1) aquifer and adjacent to the (n-1) aquifer, The aforementioned groundwater includes the (n-1) groundwater flowing in from the (n-1) aquifer, The water sampling process includes an (n-1) water sampling process for sampling the groundwater at the location of the (n-1) impermeable layer, and an n water sampling process for sampling the groundwater at the location of the n impermeable layer. The aforementioned investigation process is, The (n-1) analysis step involves analyzing the groundwater collected in the (n-1) water sampling step, An nth analysis step involves analyzing the groundwater collected in the nth water sampling step, A method for investigating the water quality of each layer according to claim 1 or 2, comprising: a (n-1) calculation step for determining the water quality of the (n-1) groundwater from the difference in the amount of substance calculated based on the (n-1) analysis result obtained in the (n) analysis step and the n analysis result obtained in the n analysis step and the inflow amount measured in the water volume measurement step.

4. The method for investigating the water quality of each layer according to any one of claims 1 to 3, wherein the water sampling pump is housed in a pump house having a suction pipe for taking in groundwater at its lower end.

5. The method for investigating the water quality of each layer according to claim 4, wherein the pump house is held so as to be movable up and down within the well.

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