Karst underground river type water source area supply area demarcation method

Abstract

The invention discloses a karst underground river type water source area supply area delimiting method, and relates to the technical field of karst hydrogeology. Comprising the following steps: acquiring basic information of a water source and preprocessing the basic information to form an initial information set; determining an initial boundary of a supply area of the water source based on a water point type, a position and surface watershed information of the water source; comprehensively analyzing and correcting to determine an uncertain section after first correction; performing field investigation and checking and reducing on the uncertain section to obtain an uncertain section after second correction; the method comprises the following steps of: performing third correction on the water source area by adopting geophysical prospecting, drilling and underground water tracing tests, checking nearby key pollution sources, determining a final boundary of a water source area supply area, dividing supply subareas according to stratum lithology, karst development degree and the final boundary of the supply area, and determining geographical boundaries of the supply area and the subareas by combining permanent marks. And finally completing demarcation of the supply area. According to the method, high-precision supply area demarcation can be completed, and the method is suitable for development, utilization and protection of karst underground river system water sources with different development degrees.

Description

Technical Field

[0001] The invention relates to the technical field of karst hydrogeology, and in particular to a method for delineating a recharge area of ​​a karst underground river type water source. Background Art

[0002] As an important water resource in the karst region of southwest China, the delineation of the recharge area of ​​karst underground river water sources has always been a complex technical issue. Existing delineation methods are mostly based on traditional surface topography and hydrogeological data, and usually rely on surface watersheds to determine the boundaries of the recharge area. Such methods have certain applicability in simple terrain, but the complexity of the karst system makes the underground river network intricate, the water flow path is hidden and difficult to predict, and the delineation results often have large errors. At the same time, the existing technology does not fully consider various factors such as the interaction between groundwater and surface water, the control of geological structure on water flow, and especially ignores the nonlinear characteristics of groundwater flow in the karst system, making it difficult to accurately define the boundaries of the recharge area.

[0003] In addition, the multi-level recharge characteristics of the karst underground river system, the complexity of the karst pipeline system and the existence of fault zones further increase the difficulty of delineating the recharge area. The existing delineation methods have limited ability to dynamically correct boundaries, especially when faced with complex karst landforms. The lack of application of emerging hydrogeochemical technologies (such as isotope tracing, hydrochemical analysis, etc.) makes it impossible to fully verify the rationality of the delineation results. In addition, the inclusion of potential pollution sources is also relatively insufficient.

[0004] Therefore, how to provide a method for delineating the recharge area of ​​karst underground river-type water sources to solve the difficulties existing in the prior art is an issue that technical personnel in this field urgently need to solve. Summary of the invention

[0005] In view of this, the present invention provides a method for delineating the recharge area of ​​a karst underground river type water source, which can cope with complex karst underground river water sources and complete high-precision recharge area delineation, and is suitable for the development, utilization and protection of karst underground river system water sources with different degrees of development.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] A method for delineating a recharge area of ​​a karst underground river type water source comprises the following steps:

[0008] S1. Obtain basic information of the water source and pre-process it to form an initial information set, determine the water point type, location, stratum lithology, geological structure, karst development degree, underground river system and permanent signs of the water source;

[0009] S2. Determine the initial boundary of the water source recharge area based on the water point type and location of the water source combined with the surface watershed information;

[0010] S3. Comprehensively analyze the lithology and geological structure of the initial boundary of the recharge area and its vicinity, and make a first correction to the initial boundary based on the analysis results to obtain the initial boundary and uncertain segment after the first correction;

[0011] S4. Conduct field surveys on the uncertainty segments after the first revision, use water chemistry tests, isotope tests, groundwater tracer tests and water level elevation comparisons to verify and reduce the uncertainty segments, and obtain the initial boundaries and uncertainty segments after the second revision;

[0012] S5. The uncertain segment after the second correction is corrected for the third time by using geophysical exploration, drilling and groundwater tracer test to obtain the initial boundary after the third correction;

[0013] S6. Check the key pollution sources near the initial boundary after the third revision. If the pollution source is located near the boundary of the recharge area, include it in the scope of the recharge area, realize the fourth revision of the initial boundary of the water source recharge area, and determine the final boundary of the water source recharge area;

[0014] S7. Divide the recharge sub-areas according to the lithology and degree of karst development in combination with the final boundary of the water source recharge area, and use obvious permanent signs to determine the geographical boundaries of the recharge area and its sub-areas, form a map and coordinate table of the water source recharge area, and finally complete the delineation of the recharge area.

[0015] In the above method, optionally, the basic information of the water source in S1 includes: topography, landform, geology, hydrogeology, hydrogeochemistry, development and utilization, and protection zone division, and the preprocessing methods include screening and vector data overlay.

[0016] In the above method, optionally, the water point types of the water source in S1 include natural water points and artificial water points;

[0017] Natural water points include underground river outlets, surface karst springs, karst pools, skylights and vertical shafts;

[0018] Artificial water points include boreholes and large wells.

[0019] In the above method, optionally, determining the initial boundary of the recharge area in S2 includes:

[0020] When the water point type of the water source is the underground river outlet, the initial boundary of the underground river system is used as the initial boundary of the recharge area;

[0021] When the water point type of the water source is other water point types, the water source location is taken as the most downstream, and the surface watershed between the water source location and its upstream is extracted as the initial boundary of the water source recharge area;

[0022] When a water source is jointly exploited by multiple water points, the union area of ​​the initial boundaries of the recharge areas of each exploitation point is used as the initial boundary of the water source recharge area.

[0023] In the above method, optionally, the first correction in S3 includes:

[0024] When the initial boundary stratum lithology is clastic rock, the initial boundary remains unchanged;

[0025] When the initial boundary stratum lithology is carbonate rock and the underground watershed is consistent with the surface watershed, the initial boundary remains unchanged;

[0026] When the initial boundary stratigraphic lithology is carbonate rock and the underground watershed is different from the surface watershed, the initial boundary is adjusted to the underground watershed. If the underground watershed cannot be determined, it is marked as an uncertain segment;

[0027] When there is a fault on the initial boundary, the intersection area between the fault-affected zone and the initial boundary needs to be marked as an uncertain segment.

[0028] In the above method, optionally, in S4, water chemistry tests include EC, pH, Ca 2+ 、HCO3 - , isotopes including hydrogen isotopes 2 H and oxygen isotopes 18 O, water level elevation was measured by RTK elevation measuring instrument, and groundwater tracer test used high-sensitivity fluorescent tracer.

[0029] In the above method, optionally, in S7, the water source recharge area is divided into a sub-area with no karst development, a sub-area with no karst development, a sub-area with moderate karst development, and a sub-area with strong karst development based on the lithology of the formation and the degree of karst development.

[0030] It can be seen from the above technical solutions that, compared with the prior art, the present invention provides a method for delineating the recharge area of ​​a karst underground river type water source, which has the following beneficial effects: 1) The present invention gradually reduces the uncertain section of the recharge area through multiple revisions, combined with hydrogeology, topography, geophysical exploration, drilling and hydrochemical testing and other means, ensures the accuracy and scientificity of the recharge area boundary, and completes the high-precision recharge area delineation; 2) The present invention integrates the information of surface watersheds, underground watersheds and pollution sources, not only considering the natural topography, but also including the potential impact of human activities on the water source recharge area, realizing multi-dimensional analysis, and ensuring that the delineated recharge area is both scientific and has practical application value; 3) The present invention adopts a variety of technical means, including hydrochemical testing, geophysical exploration, drilling and pollution source verification, to provide a comprehensive and comprehensive recharge area delineation scheme, which can effectively cope with the complexity of karst underground river water sources; 4) The present invention can be widely used in karst areas, and is suitable for the development, utilization and protection of karst underground river system water sources with different degrees of development. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0032] Figure 1 A flow chart of a method for delineating a recharge area for a karst underground river type water source disclosed in the present invention;

[0033] Figure 2 This is a schematic diagram of a method for delineating a recharge area for a karst underground river type water source disclosed in the present invention. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] Reference Figure 1 and Figure 2 As shown, the present invention discloses a method for delineating a recharge area of ​​a karst underground river type water source, comprising the following steps:

[0036] S1. Obtain basic information of the water source and pre-process it to form an initial information set, determine the water point type, location, stratum lithology, geological structure, karst development degree, underground river system and permanent signs of the water source;

[0037] S2. Determine the initial boundary of the water source recharge area based on the water point type and location of the water source combined with the surface watershed information;

[0038] S3. Comprehensively analyze the lithology and geological structure of the initial boundary of the recharge area and its vicinity, and make a first correction to the initial boundary based on the analysis results to obtain the initial boundary and uncertain segment after the first correction;

[0039] S4. Conduct field surveys on the uncertainty segments after the first revision, use water chemistry tests, isotope tests, groundwater tracer tests and water level tests to verify and reduce the uncertainty segments, and obtain the initial boundaries and uncertainty segments after the second revision;

[0040] S5. The uncertain segment after the second correction is corrected for the third time by using geophysical exploration, drilling and groundwater tracer test to obtain the initial boundary after the third correction;

[0041] S6. Check the key pollution sources near the initial boundary after the third revision. If the pollution source is located near the boundary of the recharge area, include it in the scope of the recharge area, realize the fourth revision of the initial boundary of the water source recharge area, and determine the final boundary of the water source recharge area;

[0042] S7. Divide the water source recharge area into recharge sub-areas based on the lithology and degree of karst development and the final boundary of the water source recharge area. Use obvious permanent signs to determine the geographical boundaries of the recharge area and its sub-areas, form a water source recharge area range map and coordinate table, and finally complete the delineation of the recharge area.

[0043] Furthermore, the basic information of water sources in S1 includes topography, geomorphology, geology, hydrogeology, hydrogeochemistry, development and utilization, and protection zone division, and the preprocessing methods include screening and vector data overlay.

[0044] Furthermore, basic data such as topography, geomorphology, geology, and hydrogeology are collected, specifically large-scale topographic maps (with an accuracy greater than or equal to 1:50,000) or high-resolution digital elevation models (DEMs) of the collection area, geological structure maps, lithology maps, hydrogeological maps, and groundwater flow direction.

[0045] Furthermore, the types of water points in the water sources in S1 include natural water points and artificial water points; natural water points include underground river outlets, surface karst springs, karst pools, skylights and vertical shafts; artificial water points include boreholes and large wells.

[0046] Furthermore, the water source includes water point types of the water source and joint exploitation of multiple water points, and the water point types of the water source are divided into underground river outlets and other water point types.

[0047] Furthermore, determining the initial boundary of the recharge area in S2 includes:

[0048] When the water point type of the water source is the underground river outlet, the initial boundary of the underground river system is used as the initial boundary of the recharge area;

[0049] When the water point type of the water source is other water point types, the water source location is taken as the most downstream, and the surface watershed between the water source location and its upstream is extracted as the initial boundary of the water source recharge area;

[0050] When a water source is jointly exploited by multiple water points, the union area of ​​the initial boundaries of the recharge areas of each exploitation point is used as the initial boundary of the water source recharge area.

[0051] Furthermore, the surface watershed extraction method includes: using GIS tools in combination with large-scale topographic maps or high-resolution digital elevation models (DEMs), applying automatic watershed extraction algorithms to extract surface watersheds, and verifying surface runoff and river network systems through remote sensing image analysis when necessary.

[0052] Specifically, the initial boundary of the karst underground river system is delineated in the following way: taking the existing pipeline of the karst underground river as the center, preliminarily determine the recharge-runoff-discharge range of the karst underground river; collect basic data, including topographic data, stratigraphic data, structural data and hydrogeological data, and use large-scale topographic maps (accuracy greater than or equal to 1:50000) or high-resolution digital elevation models (DEM) combined with automatic extraction algorithms to extract the surface watershed of the underground river system where the water source is located, and use it as the initial boundary of the karst underground river system.

[0053] The initial boundaries of other water point types include: collecting the geographic coordinates of the water source and its surrounding large-scale topographic maps or high-resolution digital elevation models (DEMs), using GIS software to perform watershed analysis based on topographic maps or DEM data, calculating slopes and slope directions, extracting surface water flow paths, determining surface runoff convergence points, extracting surface watersheds upstream of the water source based on the watershed boundaries, associating them with the location of the water source, and delineating the initial boundaries of the water source recharge area.

[0054] Furthermore, the first revision in S3 includes:

[0055] When the initial boundary stratum lithology is clastic rock, the initial boundary remains unchanged;

[0056] When the initial boundary stratum lithology is carbonate rock and the underground watershed is consistent with the surface watershed, the initial boundary remains unchanged;

[0057] When the initial boundary stratigraphic lithology is carbonate rock and the underground watershed is different from the surface watershed, the initial boundary is adjusted to the underground watershed. If the underground watershed cannot be determined, it is marked as an uncertain segment;

[0058] When there is a fault on the initial boundary, the intersection area between the fault-affected zone and the initial boundary needs to be marked as an uncertain segment.

[0059] Furthermore, in S4, based on the initial boundary of the water source recharge area after the first correction, field stratigraphic lithology, geological structure, topography and geomorphology surveys were conducted on the uncertain section to obtain the distribution characteristics of typical water points and karst landform points along the uncertain section of the initial boundary of the water source recharge area and the characteristics of groundwater movement in the dry and wet seasons. A comprehensive analysis was also conducted on the water chemistry, isotopes, water level elevation and groundwater tracer test data of typical water points along the uncertain section of the initial boundary of the water source recharge area in the dry season to further reduce the length of the uncertain section and complete the second correction of the initial boundary of the water source recharge area.

[0060] Furthermore, in S4, water chemistry tests include EC, pH, Ca 2+ 、HCO3 - , isotopes including hydrogen isotopes 2 H and oxygen isotopes 18O, water level elevation was measured by RTK elevation measuring instrument, and groundwater tracer test used high-sensitivity fluorescent tracer.

[0061] Furthermore, in S5, based on the initial boundary of the water source recharge area after the second correction, geophysical exploration and drilling analysis are carried out on the uncertain section to determine the local groundwater watershed, and if necessary, verification is carried out through a borehole groundwater tracer test to complete the third correction of the initial boundary of the water source recharge area.

[0062] Furthermore, in S7, the water source recharge area is divided into a sub-area with no karst development, a sub-area with undeveloped karst, a sub-area with moderately developed karst, and a sub-area with strongly developed karst based on the lithology of the formation and the degree of karst development.

[0063] In a specific embodiment, a large-scale topographic map (with an accuracy greater than or equal to 1:50,000) or a high-resolution digital elevation model (DEM), geological structure map, lithology map, hydrogeological map, groundwater flow direction and other basic data of the region are collected, and the basic data are pre-processed to control the terrain elevation accuracy within 1 meter and the basin area accuracy within 5% to form an initial data set. After verifying the surface runoff and river network system through remote sensing image analysis, the watershed range of the underground river system is preliminarily delineated, and combined with the water point location of the water source, the initial boundary of the water source recharge area is formed;

[0064] Comprehensively analyze the lithology, faults, etc. of the region to determine the development of carbonate rocks in the region. The initial boundary of the recharge area needs to be adjusted to the underground watershed of the carbonate rock area or the surface watershed of the clastic rock area. Mark the uncertain section with a width of 100 meters in the fault area, and perform hydrochemical parameters EC, Ca 2+ 、HCO3 - etc. for analysis, combined with 2 H, 18 O test to determine the hydraulic connection of the recharge area; based on a fluorescent tracer with a sensitivity of 0.01 μg / L to accurately determine the flow path and further correct the boundaries;

[0065] The corrected uncertain section was subjected to high-density resistivity method and drilling test with a detection depth of 50 meters. The boundary was corrected in combination with the borehole data, and a borehole groundwater tracer test was carried out to verify the accuracy of the watershed. The potential pollution sources around the recharge area were investigated, and it was found that the pollution source was less than 200 meters away from the boundary of the recharge area. The area was included in the recharge area, and the boundary of the water source recharge area was finally delineated. Based on the lithology and the degree of karst development, the recharge area was subdivided into different sub-areas, and the boundaries of the recharge area and its sub-areas were accurately marked to form a geographic coordinate system, and the recharge area drawings and coordinate tables were output.

[0066] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for delineating the recharge area of ​​a karst underground river type water source, characterized in that: The following steps are involved: S1. Obtain basic information of the water source and pre-process it to form an initial information set, determine the water point type, location, stratum lithology, geological structure, karst development degree, underground river system and permanent signs of the water source; S2. Determine the initial boundary of the water source recharge area based on the water point type and location of the water source combined with the surface watershed information; S3. Comprehensively analyze the lithology and geological structure of the initial boundary of the recharge area and its vicinity, and make a first correction to the initial boundary based on the analysis results to obtain the initial boundary and uncertain segment after the first correction; S4. Conduct field surveys on the uncertainty segments after the first revision, use water chemistry tests, isotope tests, groundwater tracer tests and water level elevation comparisons to verify and reduce the uncertainty segments, and obtain the initial boundaries and uncertainty segments after the second revision; S5. The uncertain segment after the second correction is corrected for the third time by using geophysical exploration, drilling and groundwater tracer test to obtain the initial boundary after the third correction; S6. Check the key pollution sources near the initial boundary after the third revision. If the pollution source is located near the boundary of the recharge area, include it in the scope of the recharge area, realize the fourth revision of the initial boundary of the water source recharge area, and determine the final boundary of the water source recharge area; S7. Divide the recharge sub-areas according to the lithology and degree of karst development in combination with the final boundary of the water source recharge area, and use obvious permanent signs to determine the geographical boundaries of the recharge area and its sub-areas, form a map and coordinate table of the water source recharge area, and finally complete the delineation of the recharge area.

2. The method for delineating the recharge area of ​​a karst underground river type water source according to claim 1, characterized in that: The basic information of water sources in S1 includes topography, landform, geology, hydrogeology, hydrogeochemistry, development and utilization, and protection zone division. The preprocessing methods include screening and vector data overlay.

3. The method for delineating the recharge area of ​​a karst underground river type water source according to claim 1, characterized in that: The types of water points in water sources in S1 include natural water points and artificial water points; Natural water points include underground river outlets, surface karst springs, karst pools, skylights and vertical shafts; Artificial water points include boreholes and large wells.

4. The method for delineating the recharge area of ​​a karst underground river type water source according to claim 1, characterized in that: Determining the initial boundaries of the recharge area in S2 includes: When the water point type of the water source is the underground river outlet, the initial boundary of the underground river system is used as the initial boundary of the recharge area; When the water point type of the water source is other water point types, the water source location is taken as the most downstream, and the surface watershed between the water source location and its upstream is extracted as the initial boundary of the water source recharge area; When a water source is jointly exploited by multiple water points, the union area of ​​the initial boundaries of the recharge areas of each exploitation point is used as the initial boundary of the water source recharge area.

5. The method for delineating the recharge area of ​​a karst underground river type water source according to claim 1, characterized in that: The first revisions in S3 include: When the initial boundary stratum lithology is clastic rock, the initial boundary remains unchanged; When the initial boundary stratum lithology is carbonate rock and the underground watershed is consistent with the surface watershed, the initial boundary remains unchanged; When the initial boundary stratigraphic lithology is carbonate rock and the underground watershed is different from the surface watershed, the initial boundary is adjusted to the underground watershed. If the underground watershed cannot be determined, it is marked as an uncertain segment; When there is a fault on the initial boundary, the intersection area between the fault-affected zone and the initial boundary needs to be marked as an uncertain segment.

6. The method for delineating the recharge area of ​​a karst underground river type water source according to claim 1, characterized in that: In S4, water chemistry tests include EC, pH, Ca 2+ 、HCO3 - , isotopes including hydrogen isotopes 2 H and oxygen isotopes 18 O, water level elevation was measured by RTK elevation measuring instrument, and groundwater tracer test used high-sensitivity fluorescent tracer.

7. The method for delineating the recharge area of ​​a karst underground river type water source according to claim 1, characterized in that: In S7, the water source recharge area is divided into non-karst development sub-area, undeveloped karst sub-area, moderately developed karst sub-area and strongly developed karst sub-area based on the lithology and degree of karst development.

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