Method for testing permeability coefficient of river-lake bed in situ

Abstract

The invention discloses a method for in-situ testing of a river-lake bed permeability coefficient, which comprises the following steps: when a river and a lake are connected with a water-bearing stratum, acquiring a lateral permeability coefficient between the river and the lake and the water-bearing stratum; when the river and the lake are not connected with the aquifer, acquiring a vertical permeability coefficient between the river and the lake and the aquifer; on the basis of the function relationship between the lateral permeability coefficient and the vertical permeability coefficient between the river and the lake and the aquifer, obtaining the permeability coefficient between the river and the lake and the aquifer; and based on the permeability coefficient between the river and lake and the aquifer, evaluating the exchange water quantity between the river and lake and underground water. According to the method for testing the permeability coefficient of the river-lake bed in situ, the true permeability coefficient between the river and the lake and the aquifer is obtained, and key parameters are provided for scientifically and quantitatively evaluating the exchange water quantity between the river and the lake and underground water.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrogeological experiments, and in particular relates to a method for in-situ testing of permeability coefficients of river and lake beds. Background Art

[0002] Under natural conditions, rivers and lakes are closely connected with aquifers. Basically, rivers and lakes seep and replenish aquifers during the flood season, and groundwater discharge and replenish rivers and lakes during the dry season. In most parts of northern my country, long-term over-exploitation of groundwater has caused the groundwater level to continue to drop, resulting in a disconnection between rivers and lakes and aquifers. The groundwater level is lower than the river and lake bed elevation, and rivers and lakes seep and replenish groundwater in one direction, causing rivers and lakes to gradually shrink or even dry up. Understanding the interaction between rivers and lakes and aquifers and the characteristics of water exchange is a prerequisite for the protection and management of rivers and lakes.

[0003] In response to the above problems, it is urgent to propose a method for in-situ testing of the permeability coefficient of rivers and lakes, so as to provide a basis for the scientific and quantitative evaluation of the amount of water exchange between rivers, lakes and groundwater. Summary of the invention

[0004] In order to solve the above technical problems, the present invention proposes a method for in-situ testing of the permeability coefficient of river and lake beds to solve the problems existing in the above-mentioned prior art.

[0005] To achieve the above object, the present invention provides a method for in-situ testing of permeability coefficient of river and lake beds, comprising the following steps:

[0006] When rivers and lakes intersect with aquifers, obtain the lateral permeability coefficient between the rivers and lakes and the aquifers;

[0007] When the river, lake and aquifer do not intersect, obtain the vertical permeability coefficient between the river, lake and aquifer;

[0008] Based on the functional relationship between the lateral permeability coefficient and the vertical permeability coefficient between the river, lake and aquifer, the permeability coefficient between the river, lake and aquifer is obtained;

[0009] Based on the permeability coefficient between the rivers, lakes and aquifers, the amount of water exchange between rivers, lakes and groundwater is evaluated.

[0010] Optionally, when a river or lake intersects with an aquifer, the process of obtaining the lateral permeability coefficient between the river or lake and the aquifer includes:

[0011] Select points in the groundwater well to place intelligent groundwater flowmeters to obtain groundwater flow velocity; select points on the river or lake bed and insert vertical straight pipes to measure the water level at the selected points on the river or lake bed; the points selected in the groundwater well and on the river or lake bed are on the same horizontal line, and the horizontal distance between the points selected in the groundwater well and on the river or lake bed is obtained;

[0012] The water level of the selected point of the groundwater well is obtained, and the lateral permeability coefficient between the river, lake and aquifer is obtained based on the functional relationship between the water level of the selected point of the groundwater well, the water level of the selected point of the river or lake bed, the groundwater flow rate and the horizontal distance between the selected points in the groundwater well and on the river or lake bed.

[0013] Optionally, the formula for the lateral permeability coefficient between the river, lake and aquifer is as follows:

[0014] K 侧 =V×l / H1-H2

[0015] Among them, K 侧 is the lateral permeability coefficient between the river, lake and aquifer, V is the groundwater flow velocity, l is the horizontal distance between the selected point in the groundwater well and the selected point on the river and lake bed, H1 is the water level of the selected point in the groundwater well, and H2 is the water level of the selected point on the river and lake bed.

[0016] Optionally, the process of obtaining the lateral permeability coefficient between the river, lake and aquifer also includes:

[0017] Arrange lateral permeability coefficient observation instruments and vertical permeability observation instruments.

[0018] Optionally, when the river, lake and aquifer do not intersect, the process of obtaining the vertical permeability coefficient between the river, lake and aquifer includes:

[0019] Insert a vertical straight pipe into a selected point on the river or lake bed, preset an observation time period, obtain the water level of the selected point on the river or lake bed before and after the observation time period, and obtain the thickness of the sediment where the vertical straight pipe is inserted into the river or lake bed; based on the functional relationship between the water level of the selected point on the river or lake bed before and after the observation time period and the sediment thickness, obtain the vertical permeability coefficient between the river or lake and the aquifer.

[0020] Optionally, the formula for the vertical permeability coefficient between the river, lake and aquifer is as follows:

[0021]

[0022] Among them, K 垂 is the vertical permeability coefficient between the river, lake and aquifer, L v is the sediment thickness of the vertical straight pipe inserted into the river or lake bed, t1 and t2 are two observation times, h1 is the water level at the selected point on the river or lake bed observed at time t1, and h2 is the water level at the selected point on the river or lake bed observed at time t2.

[0023] Optionally, the process of obtaining the vertical permeability coefficient between the river, lake and aquifer also includes:

[0024] Arrange vertical penetration observation instruments.

[0025] Alternatively, the formula for the permeability coefficient between rivers, lakes and aquifers is as follows:

[0026]

[0027] Among them, K is the permeability coefficient between rivers, lakes and aquifers, K 垂 is the vertical permeability coefficient between rivers, lakes and aquifers, K 侧 is the lateral permeability coefficient between rivers, lakes and aquifers.

[0028] Compared with the prior art, the present invention has the following advantages and technical effects:

[0029] In the prior art, the in-situ test of the permeability coefficient of river and lake bed sediments is performed by a single straight tube method, but it only represents the vertical permeability coefficient. In the case where rivers and lakes interact closely with aquifers, the lateral exchange volume often dominates. To address the above problem, the present invention observes the lateral permeability coefficient, and then directly obtains the true permeability coefficient of the river and lake bed based on the functional relationship between the lateral permeability coefficient and the vertical permeability coefficient between the river, lake and aquifer;

[0030] The present invention obtains the actual permeability coefficient between rivers, lakes and aquifers through an in-situ testing method of the permeability coefficient of river and lake beds, providing a key parameter for scientifically and quantitatively evaluating the amount of water exchange between rivers, lakes and groundwater. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0032] Figure 1 This is a schematic flow chart of a method for in-situ testing of permeability of river and lake beds according to an embodiment of the present invention;

[0033] Figure 2 Schematic diagram of the relationship between rivers, lakes and aquifers according to an embodiment of the present invention, wherein (a) is a schematic diagram of the connection between rivers, lakes and aquifers, and (b) is a schematic diagram of the non-connection between rivers, lakes and aquifers;

[0034] Figure 3 Schematic diagram of lateral and vertical monitoring of rivers, lakes and aquifers according to an embodiment of the present invention. DETAILED DESCRIPTION

[0035] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0036] It should be noted that the steps shown in the flowcharts of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and that, although a logical order is shown in the flowcharts, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0037] In order to test the permeability coefficient of rivers and lakes in situ, we conducted field surveys and water level measurements to analyze the relationship between rivers, lakes and aquifers, arranged corresponding vertical and lateral permeability observation points, recorded multiple test data, and calculated the permeability coefficient of rivers and lakes.

[0038] The specific process is as follows Figure 1 As shown, this embodiment provides a method for in-situ testing the permeability coefficient of river and lake beds, comprising the following steps: when the river, lake and aquifer are connected, obtaining the lateral permeability coefficient between the river, lake and aquifer; when the river, lake and aquifer are not connected, obtaining the vertical permeability coefficient between the river, lake and aquifer; based on the functional relationship between the lateral permeability coefficient and the vertical permeability coefficient between the river, lake and aquifer, obtaining the permeability coefficient between the river, lake and aquifer; based on the permeability coefficient between the river, lake and aquifer, evaluating the amount of water exchange between the river, lake and groundwater.

[0039] As a specific example, Figure 2 As shown in the figure, under the influence of natural conditions and human activities, there are two types of cuts between rivers, lakes and aquifers. One is the connection between rivers, lakes and aquifers. The rivers, lakes and aquifers interact closely with each other. The groundwater level is higher than the river and lake level, and the groundwater discharge replenishes the rivers and lakes. The groundwater level is lower than the river and lake level, and the river and lake infiltration replenishes the groundwater. This type of river, lake and aquifer has both lateral and vertical recharge and discharge.

[0040] The other type is that there is no connection between rivers, lakes and aquifers, that is, the groundwater level is lower than the elevation of the river and lake beds, and rivers and lakes replenish groundwater through unidirectional infiltration. In this type of situation, there is only vertical recharge between rivers, lakes and aquifers.

[0041] As a specific embodiment, a lateral permeability coefficient test and a vertical permeability coefficient test between rivers, lakes and aquifers are conducted.

[0042] The process of testing the lateral permeability coefficient between rivers, lakes and aquifers includes:

[0043] For scenarios where rivers, lakes and aquifers are closely connected, the water exchange between the river and lake beds and the aquifers includes both lateral and vertical water exchange, so it is necessary to test the lateral permeability coefficient of the aquifer. With the help of an intelligent groundwater flow meter, the lateral permeability coefficient of groundwater in the aquifer can be observed in situ. Figure 3 As shown, an intelligent groundwater flow meter is placed in the groundwater well G1, and a vertical straight pipe is inserted into the river or lake bed point S1 to measure the water level at different times.

[0044] Assuming that the groundwater level of groundwater well G1 is H1, the water level of river and lake bed point S1 is H2, the horizontal distance between G1 and S1 is l, and the groundwater velocity in the observation well is V, then the lateral permeability coefficient between aquifers is K 侧 It can be expressed as the following formula:

[0045] K 侧 =V×l / H1-H2

[0046] The process of vertical permeability test between rivers, lakes and aquifers includes:

[0047] For rivers and lakes that have no connection with aquifers and the river and lake beds recharge groundwater in a unidirectional manner, it is necessary to test the vertical permeability coefficient of the sediment. Figure 3 As shown, a vertical straight pipe is inserted into point S1 on the river or lake bed to measure the water level at different times.

[0048] Assume that the water level in the vertical straight pipe is h1 at time t1 and h2 at time t2, and the thickness of the sediment inserted into the river or lake bed is L. v , then through repeated observations, more t1, h1, t2, h2 can be obtained, and the vertical permeability coefficient of the river and lake bed K 垂 It can be expressed as the following formula:

[0049]

[0050] Furthermore, after measuring the lateral permeability and vertical permeability coefficients respectively, the permeability coefficient K between the river, lake and aquifer can be expressed as follows:

[0051]

[0052] This embodiment obtains the actual permeability coefficient between rivers, lakes and aquifers by in-situ testing of the permeability coefficient of river and lake beds, providing key parameters for scientifically and quantitatively evaluating the amount of water exchange between rivers, lakes and groundwater.

[0053] The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for in-situ testing of permeability coefficient of river and lake beds, characterized in that: The following steps are involved: When rivers and lakes intersect with aquifers, obtain the lateral permeability coefficient between the rivers and lakes and the aquifers; When the river, lake and aquifer do not intersect, obtain the vertical permeability coefficient between the river, lake and aquifer; Based on the functional relationship between the lateral permeability coefficient and the vertical permeability coefficient between the river, lake and aquifer, the permeability coefficient between the river, lake and aquifer is obtained; Based on the permeability coefficient between the rivers, lakes and aquifers, the amount of water exchange between rivers, lakes and groundwater is evaluated.

2. The method for in-situ testing of permeability coefficient of river and lake beds according to claim 1, characterized in that: When a river or lake intersects with an aquifer, the process of obtaining the lateral permeability coefficient between the river or lake and the aquifer includes: Select points in the groundwater well to place intelligent groundwater flowmeters to obtain groundwater flow velocity; select points on the river or lake bed and insert vertical straight pipes to measure the water level at the selected points on the river or lake bed; the points selected in the groundwater well and on the river or lake bed are on the same horizontal line, and the horizontal distance between the points selected in the groundwater well and on the river or lake bed is obtained; The water level of the selected point of the groundwater well is obtained, and the lateral permeability coefficient between the river, lake and aquifer is obtained based on the functional relationship between the water level of the selected point of the groundwater well, the water level of the selected point of the river or lake bed, the groundwater flow rate and the horizontal distance between the selected points in the groundwater well and on the river or lake bed.

3. The method for in-situ testing of permeability coefficient of river and lake beds according to claim 2, characterized in that: The formula for the lateral permeability coefficient between the river, lake and aquifer is as follows: K 侧 =H×l / H1-H2 Among them, K 侧 is the lateral permeability coefficient between the river, lake and aquifer, V is the groundwater flow velocity, l is the horizontal distance between the point selected in the groundwater well and the point on the river or lake bed, H1 is the water level at the point selected in the groundwater well, and H2 is the water level at the point selected in the river or lake bed.

4. The method for in-situ testing of permeability coefficient of river and lake beds according to claim 1, characterized in that: When the river, lake and aquifer do not intersect, the process of obtaining the vertical permeability coefficient between the river, lake and aquifer includes: Insert a vertical straight pipe into a selected point on the river or lake bed, preset an observation time period, obtain the water level of the selected point on the river or lake bed before and after the observation time period, and obtain the thickness of the sediment where the vertical straight pipe is inserted into the river or lake bed; based on the functional relationship between the water level of the selected point on the river or lake bed before and after the observation time period and the sediment thickness, obtain the vertical permeability coefficient between the river or lake and the aquifer.

5. The method for in-situ testing of permeability coefficient of river and lake beds according to claim 4, characterized in that: The formula for the vertical permeability coefficient between the river, lake and aquifer is as follows: Among them, K 垂 is the vertical permeability coefficient between the river, lake and aquifer, L v is the sediment thickness of the vertical straight pipe inserted into the river or lake bed, t1 and t2 are two observation times, h1 is the water level at the selected point on the river or lake bed observed at time t1, and h2 is the water level at the selected point on the river or lake bed observed at time t2.

6. The method for in-situ testing of permeability coefficient of river and lake beds according to claim 1, characterized in that: The formula for the permeability coefficient between rivers, lakes and aquifers is as follows: Among them, K is the permeability coefficient between rivers, lakes and aquifers, K 垂 is the vertical permeability coefficient between rivers, lakes and aquifers, K 侧 is the lateral permeability coefficient between rivers, lakes and aquifers.

Images