A simple method for measuring groundwater flow direction and velocity using shore wells

Abstract

The present invention discloses a method for simply measuring the flow direction and velocity of groundwater using a shore water well. The method comprises the following steps: Step 1: Survey the shore water well and measure the groundwater level elevation H at the center point A of the well. A ; Step 2: Measure and locate the water line along the shore A The water level elevation point B is equal; Step 3: connect line AB, draw a perpendicular line CD through point A, and drill a hole at point E on line CD; Step 4: conduct a permeability test in the borehole to obtain the permeability coefficient K of the aquifer; Step 5: after the borehole is completed, conduct water level observation to obtain the stable groundwater level elevation H in the borehole E ; Step 6, according to H A 、H E The relative size and the principle that water flows from high water level to low water level determine the direction of groundwater flow; Step 7: According to Darcy's law of seepage v = K·i, determine the groundwater flow velocity. The present invention has the advantages of accurate and reliable measurement results and saves drilling workload and man-hours.

Description

Technical Field

[0001] The present invention relates to the fields of engineering survey and hydrogeological testing. Specifically, it is a method for simply measuring groundwater flow direction and velocity using bank wells. More specifically, the method uses a bank well as a center point, plots groundwater isolevels based on the river water level, and combines borehole water level observations, permeability tests, and Darcy's law to simply determine groundwater flow direction and velocity. Background Art

[0002] Groundwater, stored in the rock and soil voids beneath the Earth's surface, is a vital component of water resources and is closely linked to human survival and the geological environment. Measuring groundwater flow direction and velocity is a key task in water resource investigation and utilization, water environment protection, and hydrogeological disaster prevention and control.

[0003] At present, the direction of groundwater flow is generally determined by the three-point method, that is, using three boreholes to form a triangle, the water level elevation in the borehole is measured, and the groundwater flow direction is determined on the drawn isowater level line map. After the flow direction is determined, another borehole is drilled in the direction of the flow using the existing borehole, and the groundwater flow velocity is directly measured using the indicator method. The above-mentioned method for measuring groundwater flow direction and velocity has the following obvious shortcomings: (1) The drilling workload is large, and at least four boreholes are required to achieve the purpose of measuring groundwater flow direction and velocity; (2) Some aquifers have complex material composition, uneven structure, and different pore sizes and shapes, making it difficult to measure the velocity using the indicator method. In addition, the indicator itself will diffuse in the water environment, causing interference to the test; (3) The indicator used in the test will remain permanently in the underground aquifer, which will have an adverse impact on the environment and water quality.

[0004] Therefore, it is necessary to develop a method for testing groundwater flow direction and velocity that is accurate and reliable, can save drilling workload and working hours, and has no adverse effects on the environment and water quality. Summary of the Invention

[0005] The purpose of the present invention is to overcome the shortcomings of the background technology and provide a method for simply measuring the flow direction and velocity of groundwater using shore water wells. The method is a test method that takes the river / river bank water well as the center, draws groundwater isowater lines in combination with the river / river water level, and combines borehole water level observation, permeability test and Darcy's law to quickly determine the flow direction and velocity of groundwater. The results obtained are accurate and reliable, saving drilling workload and working hours, saving construction costs, and having no adverse effects on the environment and water quality; it overcomes the defects of the traditional method of using indicators, because the indicators themselves will diffuse in the water environment, which will interfere with the test and affect the accuracy and reliability of the groundwater flow velocity test results; at the same time, it overcomes the defects of the traditional method of requiring four drillings to obtain the groundwater flow direction and velocity, which is labor-consuming and time-consuming, and has high construction costs.

[0006] In order to achieve the above object, the technical solution of the present invention is: a method for simply measuring the flow direction and velocity of groundwater using a shore well, characterized by comprising the following steps:

[0007] Step 1: Investigate the water wells on the shore and measure the groundwater level elevation H at the center point A of the well. A ;

[0008] Step 2: Measure and locate the water line along the shore A Equal water level point B;

[0009] Step 3: Connect line AB, draw a perpendicular line CD through point A, and drill a hole at point E on line CD.

[0010] Step 4: Conduct a permeability test in the borehole to obtain the permeability coefficient K of the aquifer;

[0011] Step 5: After the drilling is completed, the water level is observed to obtain the stable groundwater level elevation H in the borehole. E ;

[0012] Step 6: According to H A 、H E The direction of groundwater flow is determined by relative size and the principle that water flows from high water levels to low water levels;

[0013] Step 7: Determine the groundwater velocity based on Darcy's law of seepage v = K·i; where the seepage hydraulic gradient i = |H A -H E ∣ / L; where: v is the groundwater velocity, in cm / s; K is the permeability coefficient of the aquifer, in cm / s; L is the horizontal distance between point E and point A, in meters.

[0014] In the above technical solution, in step 1, a water well survey is conducted along the river / river. The survey content includes topography, aquifer and water extraction layer types, water quality characteristics, wellhead shape, cross-sectional dimensions, well depth, the closest distance between the well and the river / river and other surface water bodies, well construction time, mining method, main use, and possible pollution sources in the surrounding area;

[0015] The groundwater level elevation H at the center point A of the well A Measure with an instrument.

[0016] In the above technical solution, in step 2, the river / river water level elevation H is measured along the river / river bank water edge. B and through H B =H A Accurately locate point B; measure the river / river water level elevation with an instrument, and retain the result to two decimal places.

[0017] In the above technical solution, in step three, the water level elevations of all points on line segment AB are equal; the horizontal distance L between the borehole and the water well is the distance between point E and point A; L takes a value in the range of 30 to 100 meters, and takes a larger value when the terrain is flat, and otherwise takes a smaller value.

[0018] In the above technical solution, in step 4, the diameter of the drill hole is 75 to 150 mm; the permeability test section and the water well water layer are in the same aquifer and have the same hydrogeological conditions;

[0019] The permeability test adopts water injection or pumping test; when multiple permeability tests are carried out in the same aquifer, the average value of the test results is taken as the aquifer permeability coefficient K.

[0020] In the above technical solution, in step 5, the groundwater level in the borehole is E Measure with an instrument and keep the result to two decimal places; when the water level change amplitude is less than 5 cm / min for two consecutive times, the observation is terminated and the final observation result is used as the groundwater level elevation H in the borehole. E .

[0021] In the above technical solution, in step 6, the groundwater flow direction is perpendicular to the groundwater isowater level line and flows from the high water level to the low water level; when H A >H E When H A <H E When , the groundwater flows from point E to point A.

[0022] The method provided by the present invention for simply measuring the flow direction and velocity of groundwater using a shore well has the following beneficial effects:

[0023] (1) The present invention is a direct method that can directly and simultaneously measure groundwater flow direction and groundwater flow velocity. The test results are accurate and reliable, and it is time-saving and efficient. It overcomes the shortcomings of the existing technology that uses indirect methods and complex algorithms such as numerical simulation and inversion analysis to obtain only one parameter of groundwater flow direction or flow velocity, and the operation is complicated and time-consuming.

[0024] (2) The present invention is based on Darcy's basic law of seepage and is applicable to aquifers with different degrees of geological complexity. The results are accurate and reliable, and there is no need for long-term indicator observation, which saves man-hours (the present invention uses the classic Darcy's law to calculate the groundwater flow rate, and the results are more accurate and reliable; it overcomes the defect of the traditional method of using indicators, because the indicators themselves will diffuse in the water environment, which will interfere with the test and affect the accuracy and reliability of the groundwater flow rate test results).

[0025] (3) The purpose of measuring the direction and velocity of groundwater flow can be achieved by drilling only one hole, which can save a lot of drilling work. The present invention only needs to drill one hole near an existing water well to achieve the purpose. Compared with the existing technology, it can save the construction cost and time of three holes, and is more efficient. It overcomes the defects of the traditional method of drilling four holes to obtain the direction and velocity of groundwater flow, which is labor-consuming, time-consuming, and has high construction costs. In addition, the test process has no adverse effects on the environment and water quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Flowchart of the present invention.

[0027] Figure 2 This is a test arrangement diagram of the present invention.

[0028] exist Figure 2 In, H A H is the groundwater level elevation at the center point A of the well; B H is the water level elevation at point B on the river bank; E is the groundwater level elevation in the borehole implemented at point E; L is the horizontal distance between the borehole (point E) and the well (point A), and the units of elevation and distance are both meters.

[0029] In the figure, 1-well, 2-groundwater level in the well, 3-river / river bank water edge, 4-river / river water level, 5-river / river flow direction, 6-borehole, 7-groundwater level in the borehole. DETAILED DESCRIPTION

[0030] The following detailed description of the embodiments of the present invention is given in conjunction with the accompanying drawings, which do not limit the present invention but are merely examples. The description makes the advantages of the present invention clearer and easier to understand.

[0031] River / river terraces and beach lands have gentle terrain and open topography, where urban residents are generally concentrated, or where there are cultivated land, grassland, etc. They are the main places for people's production and life, and are also key areas for carrying out water resource investigation and utilization, water environment protection, hydrogeological disaster prevention and control, etc. In these areas, the present invention can take advantage of the favorable conditions of the local shore wells that have been built, and innovate the method of measuring groundwater flow direction and velocity according to local conditions. The method is simple to operate, the accounting results are accurate and reliable, and there is no need for long-term indicator observation, which saves man-hours, and the test process has no adverse effects on the environment and water quality; it overcomes the problems of the current measurement technology, such as the large drilling workload, the difficulty of the indicator method for velocity measurement, and the fact that the indicator itself will diffuse in the water environment, causing interference to the test; the indicator used in the test will permanently remain in the underground aquifer, causing adverse effects on the environment and water quality.

[0032] As shown in the attached figure, the method for simply measuring the flow direction and velocity of groundwater using a shore well includes the following steps:

[0033] Step 1: Investigate the water wells on the shore and measure the groundwater level elevation H at the center point A of the well. A ;

[0034] Step 2: Measure and locate the water line along the shore A Equal water level point B;

[0035] Step 3: Connect line AB, draw a perpendicular line CD through point A, and drill a hole at point E on line CD.

[0036] Step 4: Conduct a permeability test in the borehole to obtain the permeability coefficient K of the aquifer;

[0037] Step 5: After the drilling is completed, the water level is observed to obtain the stable groundwater level elevation H in the borehole. E ;

[0038] Step 6: According to H A 、H E The direction of groundwater flow is determined by relative size and the principle that water flows from high water levels to low water levels;

[0039] Step 7: According to Darcy's law of seepage v = K·i, determine the groundwater flow rate (such as Figure 1 As shown); where, the seepage hydraulic gradient i=|H A -H E ∣ / L; where: v is the groundwater velocity, in cm / s; K is the permeability coefficient of the aquifer, in cm / s; L is the horizontal distance between point E and point A, in meters.

[0040] Furthermore, in step 1, a water well 1 survey is conducted along the river / river (the aquifer from which the water well is drawn is determined through the survey. During step 3, drilling should be conducted into the aquifer to ensure that the groundwater level in the borehole observed in step 5 is the same as the water level of the aquifer from which the water well is drawn, thereby improving the accuracy of the test and the accuracy of the results of groundwater flow direction and velocity). The survey content includes topography, aquifer and water-drawing layer types, water quality characteristics, wellhead shape, cross-sectional dimensions, well depth, the closest distance between the well and surface water bodies such as the river / river, well completion time, extraction method, main use, and possible pollution sources in the surrounding area.

[0041] Due to the differences in hydrogeological conditions, the groundwater flow direction and velocity are different at each location. For wells where the flow direction and velocity need to be measured, the groundwater level elevation H at the center point A of the well should be measured. A ;

[0042] The groundwater level at the center point A of the well is 2 degrees above sea level H A Measured by instruments (water level measuring instrument, level or total station, etc.), the unit is meter, and the result is rounded to two decimal places.

[0043] Furthermore, in step 2, the elevation H of the river / river water level 4 is measured along the river / river bank water edge 3. B (like Figure 2 As shown), and through H B =H A Accurately locate point B, the water level at this point should be the same as the groundwater level H at the center point A of the well. A Equal, that is, H B =H A ; The river / river water level elevation is measured by instruments (such as total station) in meters, and the result is rounded to two decimal places.

[0044] Furthermore, in step 3, the water level elevations of all points on line segment AB are equal, which is actually equivalent to the isowater level line. The borehole is located on the perpendicular line CD of line segment AB. The horizontal distance L between borehole 6 and well 1 is the distance between point E and point A (e.g. Figure 2 The unit of L is meter. The size of L is related to the terrain slope at that location. Because the terrain slope of river / river bank terraces and beach is generally small, L can be in the range of 30 to 100 meters. When the terrain is flat (slope is less than or equal to 5 degrees), L takes a larger value, otherwise it takes a smaller value.

[0045] Furthermore, in step 4, the borehole 6 is a normal aperture, which can be 75 to 150 mm in diameter. Because a permeability test is to be conducted, a pipe and clean water flushing fluid should be used when drilling the test section, and mud should not be used as a flushing fluid. The permeability test section should be in the same aquifer as the well water layer and have the same hydrogeological conditions.

[0046] The permeability test can be carried out by water injection or pumping test, and should be carried out strictly in accordance with the requirements of existing technical standards; when multiple permeability tests are carried out in the same aquifer, the average value of the test results is taken as the aquifer permeability coefficient K, in centimeters per second.

[0047] Furthermore, in step five, after the drilling construction is completed, the groundwater level 7 in the borehole should be observed;

[0048] The elevation H of the groundwater level in the borehole E Measure with an instrument (water level meter, level or total station, etc.) in meters, with the result rounded to two decimal places. When the water level change amplitude is less than 5 cm / min for two consecutive times, the observation can be terminated, and the final observation result is used as the groundwater level elevation H in the borehole. E .

[0049] Furthermore, in step 6, the groundwater flow direction is perpendicular to the groundwater isowater level line and points from the high water level to the low water level; when H A >H EWhen H A <H E When , the groundwater flows from point E to point A.

[0050] Example

[0051] The present invention is now described in detail by taking the application of the present invention to a certain river for measuring the groundwater flow direction and velocity as an example, which can also provide guidance for the application of the present invention to the measurement of groundwater flow direction and velocity in other rivers.

[0052] See attached Figure 1 It can be seen that this embodiment uses the method of the present invention for simply measuring the groundwater flow direction and velocity using a shore well to measure the groundwater flow direction and velocity of a river, including the following steps:

[0053] In step 1, a water well 1 is surveyed along a river. A large well is located on the beach on the left bank of the river. The aquifer and the water intake layer are both gravel and phreatic types. The water quality is clear and has a mutual replenishment and drainage relationship with the river water and a close hydraulic connection. The wellhead of the large well 1 is square in shape with a side length of 35 meters. It is 125 meters away from the river. Water is taken intermittently for irrigation of trees on the beach. There are no pollution sources around it. During the survey, a total station is used to measure the groundwater level 2 at the center point A of the large well in meters. The result is rounded to two decimal places, i.e., H A =3574.12 meters.

[0054] In step 2 ( Figure 2 ), on the bank of a river, measure the river water level along the river edge and accurately locate point B. The water level at this point should be the same as the groundwater level H at the center point A of the well. A Equal, that is, H B =H A =3574.12 meters; the water level elevation of a river is measured by a total station, the unit is meter, and the result is rounded to two decimal places.

[0055] In step three ( Figure 2 ), connect line AB, draw a perpendicular line CD through point A, and drill hole 6 at point E on line CD; the water level elevations of all points on line segment AB are equal, which is actually equivalent to the isowater level line, and borehole 6 is located on the perpendicular line CD of line segment AB; the horizontal distance L between borehole 6 and well 1, that is, the distance between point E and point A, is in meters; the size of L is related to the terrain slope at that location, because the terrain of a certain river beach is flat (slope is less than or equal to 5 degrees), L = 90 meters.

[0056] In step 4 ( Figure 2), water injection or pumping test was carried out in the borehole to obtain the permeability coefficient K of the aquifer; the borehole number is SK04, the depth is 20.8 meters, the borehole diameter is 130 mm in the 0-2.8 m depth section, 110 mm in the 2.8-14.8 m depth section, and 91 mm in the 14.8-20.8 m depth section; because of the permeability test, the drilling was carried out with the follower pipe and clean water flushing fluid instead of mud as the flushing fluid; the permeability test section and the large well water layer were in the same aquifer, both of which were gravel submerged aquifers; the permeability test was carried out by water injection or pumping test in strict accordance with the requirements of existing technical standards; four water injection tests and one pumping test were carried out, and the minimum permeability coefficient obtained from these five permeability tests was 8.3×10 -3 cm / s, maximum value 9.4×10 -2 cm / s, and the average value of the test results is taken as the permeability coefficient K of the aquifer, that is, K = 6.8×10 -2 cm / s.

[0057] In step five ( Figure 2 ), after the drilling construction is completed, the borehole stable water level 7 is observed; the groundwater level elevation H in the borehole E The water level measurement instrument is combined with the total station to measure the water level in meters, and the result is rounded to two decimal places. The water level observation lasts for 2 hours and 45 minutes. The observation is terminated when the water level change amplitude is less than 5 cm / minute for two consecutive times. The final observation result is used as the groundwater level elevation H in the borehole. E , that is, H B =3573.79 meters;

[0058] In step 6, the groundwater flow direction is perpendicular to the groundwater level line and points from high water level to low water level; because H A >H E When , the groundwater flows from point A to point E.

[0059] In step 7, the groundwater flow rate is determined according to Darcy's law of seepage, and the hydraulic gradient i = |H A -H E ∣ / L=∣3574.12-3573.79∣ / 90=3.67×10 -3 , K = 6.8 × 10 -2 cm / s; groundwater velocity v=K·i=6.8×10 -2 ×3.67×10 -3 =2.5×10 -4 cm / s, that is, the groundwater flow rate is 2.5×10 -4 cm / s.

[0060] Conclusion: The results of the groundwater flow direction and velocity of a river measured by the method of the present invention in this example are accurate and reliable, and are basically the same as the results of the long-term groundwater dynamic monitoring conducted during the construction and operation periods.

[0061] This method, which uses shore-side wells to simply measure groundwater flow direction and velocity, has been successfully tested in geological surveys at the Senburi Water Plant in Gonggar County, Shannan City, Tibet Autonomous Region; the Yangtze River main embankment reinforcement project in Huanggang City, Hubei Province; and the pumped-storage hydropower station in Fang County, Hubei Province. Long-term groundwater dynamic monitoring conducted during construction and operation has proven the accuracy and reliability of the measurements.

[0062] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

[0063] The contents not described in detail in this specification belong to the prior art known to those skilled in the art.

Claims

1. A method for simply measuring groundwater flow direction and velocity using a shore well, characterized by: The following steps are included: Step 1: Investigate the water wells on the shore and measure the groundwater level elevation H at the center point A of the well. A ; Step 2: Measure and locate the water line along the shore A Equal water level point B; Step 3: Connect line AB, draw a perpendicular line CD through point A, and drill a hole at point E on the perpendicular line CD. Step 4: Conduct a permeability test in the borehole to obtain the permeability coefficient K of the aquifer; Step 5: After the drilling is completed, the water level is observed to obtain the stable groundwater level elevation H in the borehole. E ; Step 6: According to H A 、H E The direction of groundwater flow is determined by relative size and the principle that water flows from high water levels to low water levels; Step 7: Determine the groundwater velocity based on Darcy's law of seepage v = K·i; where the seepage hydraulic gradient i = |H A -H E ∣ / L; where: v is the groundwater velocity, in cm / s; K is the permeability coefficient of the aquifer, in cm / s; L is the horizontal distance between point E and point A, in meters.

2. The method for simply measuring groundwater flow direction and velocity using a shore well according to claim 1, characterized in that: In step 1, a water well (1) survey is conducted along the river / river bank. The survey content includes topography, aquifer and water extraction layer types, water quality characteristics, wellhead shape, cross-sectional dimensions, well depth, the closest distance between the well and the river / river surface water body, well construction time, mining method, main use, and possible pollution sources in the surrounding area; Groundwater level at the center point A of the well (2) elevation H A Measure with an instrument.

3. The method for simply measuring groundwater flow direction and velocity using a shore well according to claim 1 or 2, characterized in that: In step 2, at the river bank, measure the river water level (4) along the river bank water line (3) to obtain the elevation H. B and through H B =H A Accurately locate point B; measure the river / river water level elevation with an instrument, and retain the result to two decimal places.

4. The method for simply measuring groundwater flow direction and velocity using a shore well according to claim 3, characterized in that: In step 3, the water level elevations of all points on line segment AB are equal; the horizontal distance L between the borehole (6) and the well (1) is the distance between point E and point A; L is taken in the range of 30 to 100 meters, and when the terrain is flat, L takes a larger value, otherwise it takes a smaller value.

5. The method for simply measuring groundwater flow direction and velocity using a shore well according to claim 4, characterized in that: In step 4, the diameter of the borehole (6) is 75 to 150 mm; the permeability test section and the water well water layer are in the same aquifer and have the same hydrogeological conditions; The permeability test adopts water injection or pumping test; when multiple permeability tests are carried out in the same aquifer, the average value of the test results is taken as the aquifer permeability coefficient K.

6. The method for simply measuring groundwater flow direction and velocity using a shore well according to claim 5, characterized in that: In step 5, the groundwater level (7) in the borehole is elevated to H E Measure with an instrument and keep the result to two decimal places; when the water level change amplitude is less than 5 cm / min for two consecutive times, the observation is terminated and the final observation result is used as the groundwater level elevation H in the borehole. E .

7. The method for simply measuring groundwater flow direction and velocity using a shore well according to claim 6, characterized in that: In step 6, the groundwater flow direction is perpendicular to the groundwater isowater level line and points from high water level to low water level; when H A >H E When H A <H E When , the groundwater flows from point E to point A.

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