Shore filtration system and method based on inclined water intake well

Abstract

The invention discloses a bank filtration system and method based on an inclined water intake well. The bank filtering system is suitable for underground water taking in a karst landform area, and comprises a filtering layer comprising natural sediments and / or artificial enhancement media of a surface water bank; the first aquifer is formed by carrying out bank filtration on the surface water by the filter layer; optionally at least one second aquifer located spatially below the first aquifer; the inclined water taking well extends towards the filtering layer at the angle that the included angle between the shaft axis and the horizontal direction is larger than 0 degree and smaller than 90 degrees, and the water taking section of the water taking well penetrates through or extends into the recoverable water-rich section of the first water-containing layer from the bank filter and at least one optional second water-containing layer. The inclined water taking well is introduced, the horizontal projection length of the water taking well is increased, the water catchment area and the effective water inlet section are remarkably increased, and more bank filtered water from lateral infiltration of a surface water bank can be collected.

Description

Technical Field

[0001] This article relates to the field of water treatment technology, and in particular to a bank filtration system and method based on inclined intake wells. This bank filtration system is especially suitable for water intake in complex hydrogeological conditions such as karst landform areas. Background Technology

[0002] Bank filtration is a process that utilizes the soil and sediment layers of river or lake shores as a natural filter. Surface water is driven by a natural hydraulic gradient to infiltrate and flow through this natural filter, ultimately extracting water that has been purified through physical, chemical, and biological processes.

[0003] Karst landforms are dominated by carbonate rocks (such as limestone and dolomite), with intense karstification forming numerous caves, conduits, and fissure networks. The soil layer in karst areas is thin, and the rocks are highly permeable, allowing rainwater to infiltrate rapidly. Water resources are mainly concentrated in deep underground fissures and conduit systems. Groundwater flows rapidly and has complex flow patterns, with extremely uneven spatial distribution of aquifers, making the search and extraction process difficult and costly. Therefore, karst landforms are characterized by rapid surface water loss and deep, difficult-to-extract groundwater. Furthermore, there is a seasonal water shortage problem: while there is abundant rainfall during the rainy season, it is quickly lost, and surface water sources dry up rapidly during the dry season. In addition, surface pollutants can easily enter groundwater directly through karst conduits or large fissures, causing "short-path" pollution and posing a high risk to water quality safety.

[0004] Furthermore, my country's ecological red line policy explicitly restricts or prohibits engineering construction activities in key water source conservation areas and key soil and water conservation areas. Since ecological red lines are mostly located in sensitive and vulnerable areas of water sources, engineering approvals within these areas are complex and subject to numerous restrictions. This renders traditional water intake methods extremely unsuitable within ecological red line areas, preventing the direct development and utilization of many areas with favorable hydrogeological conditions, further exacerbating the local water supply and demand imbalance and increasing the difficulty of implementing water intake projects.

[0005] Therefore, in karst landform areas, traditional shore filtration technology and conventional water intake methods face severe challenges, and there is an urgent need for a water intake technology with high system stability and high purification efficiency. Summary of the Invention

[0006] This application provides a shore filtration system and method based on inclined intake wells. By introducing inclined intake wells and extending their horizontal projection length, the catchment area and effective inlet cross-section are significantly increased, which helps to collect more shore filtration water from lateral infiltration of surface water. At the same time, when the inclined intake well passes through multiple aquifers, including shore filtration aquifers and aquifers located below them, it can collect more shore filtration water and efficiently collect heterogeneous groundwater, thereby increasing the water intake and optimizing the water source ratio. This can effectively improve the stability and purification efficiency of the water intake system, and is especially suitable for complex hydrogeological conditions such as karst landforms.

[0007] In a first aspect, embodiments of this application provide a bank filtration system based on an inclined intake well, wherein the bank filtration system is suitable for groundwater intake in karst landform areas, and includes: Filtering layers, including natural sediments and / or artificial reinforcing media on the surface waterfront; The first aquifer is formed by the filtration layer filtering surface water from the shore. At least one of the optional second aquifers is located spatially below the first aquifer; An inclined intake well extends toward the filter layer at an angle greater than 0° and less than 90° between the well shaft axis and the horizontal direction. The intake section of the intake well passes through or extends into the exploitable water-rich section of the first aquifer and optionally at least one second aquifer from the bank filter.

[0008] Secondly, embodiments of this application provide a bank filtration method based on an inclined intake well. This bank filtration method utilizes the bank filtration system described in the first aspect and is suitable for groundwater extraction in karst landform areas, comprising: Water from the first aquifer and at least one of the optional second aquifers in the bank filtration system is collected by the intake section of the inclined intake well and extracted through the water intake device. In addition, by monitoring and controlling the collection of water quality parameters and / or hydrological data in the inclined water intake well, the start-up and shutdown status of the water intake device, the water intake rate and / or the water intake ratio for different aquifers are adjusted.

[0009] The beneficial effects of the technical solutions in the embodiments of this application are as follows: The shore filtration system based on inclined intake wells provided in this application is suitable for karst landforms. By introducing an inclined intake well structure, the seepage path and water intake efficiency are optimized, thereby increasing the water intake volume and optimizing the water source ratio.

[0010] The bank filtration system based on inclined intake wells provided in this application is particularly suitable for riverbanks in karst landform areas where the structure is often characterized by "adhesion above and leakage below," and where ideal filter layers (such as fine sand, silt, or gravel layers) of a certain thickness and continuity exist only locally. By using inclined intake wells, the intake section can be deployed horizontally in these target layers (such as fine sand, silt, or gravel layers) with maximized contact length. In this way, even if the natural filter layer is discontinuous vertically (clay above and bedrock below), the inclined intake well can "track" and fully utilize the relatively high-quality filter section in the horizontal direction, using it as the main filtration and purification channel to ensure water intake efficiency and water quality.

[0011] The shore filtration system based on inclined intake wells provided in this application embodiment allows the wellhead to be located outside the ecological red line area. Through directional drilling, the well body extends into the aquifer within the red line, thereby achieving directional extraction of groundwater resources within the red line area without affecting the ecological environment. This system minimizes disturbance to surface vegetation, soil, and landscape in the ecological red line area, fully complying with the protection requirements for ecological red line areas and providing an innovative approach to resolving the conflict between water resource utilization and protection in ecologically sensitive areas.

[0012] The shore filtration system based on inclined intake wells provided in this application embodiment, combined with a monitoring and control unit, can achieve precise control of the shore filtration process, significantly improve the shore filtration system's ability to remove suspended solids, microorganisms and pharmaceutical pollutants, and control the water intake ratio of different aquifers to ensure long-term stability of effluent water quality and water supply safety.

[0013] Other features and advantages of this application will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the application. Other advantages of this application can be realized and obtained by means of the embodiments described in the description and the accompanying drawings. Attached Figure Description

[0014] The accompanying drawings are used to provide an understanding of the technical solutions of this application and constitute a part of the specification. They are used together with the embodiments of this application to explain the technical solutions of this application and do not constitute a limitation on the technical solutions of this application.

[0015] Figure 1 Here are schematic cross-sectional views (a) and hydrogeological columnar diagrams (b) of the inclined water intake wells in this application. Figure 2The following diagram illustrates the turbidity of river water and bank-filtered water obtained from the bank-filtered system based on the inclined intake well, as well as the turbidity removal rate of the bank filter in the embodiments of this application: (a) Turbidity of river water and bank-filtered water and turbidity removal rate of the bank filter; (b) Turbidity of river water; (c) Turbidity of bank-filtered water; (d) Turbidity removal rate of the bank filter. Figure 3 This is a comparison chart of the concentrations of nitrate nitrogen and total nitrogen in river water and bank-filtered water from a bank-filtered system based on an inclined intake well, as shown in the embodiments of this application. Figure 4 This is a graph showing the median removal rate of pharmaceutical pollutants by the shore filtration system based on the inclined intake well in the embodiments of this application. Figure 5 This is a comparison chart of total bacterial count and Escherichia coli count in river water and bank-filtered water from a bank-filtered system based on an inclined intake well, as shown in the embodiments of this application. Detailed Implementation

[0016] This application describes several embodiments, but these descriptions are exemplary and not restrictive, and it will be apparent to those skilled in the art that many more embodiments and implementations are possible within the scope of the embodiments described herein. Although many possible combinations of features are shown in the accompanying drawings and discussed in the detailed description, many other combinations of the disclosed features are also possible. Unless specifically limited, any feature of any embodiment may be used in combination with any other feature in any other embodiment, or may substitute for any other feature in any other embodiment.

[0017] The inventors discovered that traditional shore filtration technology and conventional water intake methods face severe challenges in karst landform areas. Traditional vertical wells face three core problems. First, low water intake efficiency: vertical wells struggle to effectively track and converge network-like or strip-like underground runoff. Their vertical structure often only exposes individual fissures or dissolution channels, resulting in limited and unstable water output. Simultaneously, the limited contact area between the well wall and the main water-bearing fissures restricts the rate of groundwater recharge into the well. Second, high water quality safety risks: vertical wells easily become "short-circuit channels" for surface pollutants to directly and rapidly enter deep groundwater or aquifers through karst channels or large fissures. During heavy rains, highly turbid and heavily polluted surface water may enter the well without adequate filtration, seriously threatening water supply security. Third, the construction of the filter layer is difficult: the riverbank zone in karst areas often has a "sticky upper layer and leaky lower layer" structure, that is, a thin layer of clay on top and highly permeable gravel or bedrock directly below. The natural filter layer is weak or discontinuous, making it difficult to rely on it to achieve stable water purification.

[0018] Therefore, in karst landform areas, there is an urgent need for a water intake and purification system with high water collection efficiency, stable and large water intake volume, and good filtration and purification effect. This application provides a bank filtration system and method based on inclined intake wells, suitable for karst landforms.

[0019] In a first aspect, embodiments of this application provide a bank filtration system based on an inclined intake well, wherein the bank filtration system is suitable for groundwater intake in karst landform areas, and includes: Filtering layers, including natural sediments and / or artificial reinforcing media on the surface waterfront; The first aquifer is formed by the filtration layer filtering surface water from the shore. At least one of the optional second aquifers is located spatially below the first aquifer; An inclined intake well extends toward the filter layer at an angle greater than 0° and less than 90° between the well shaft axis and the horizontal direction. The intake section of the intake well passes through or extends into the exploitable water-rich section of the first aquifer and optionally at least one second aquifer from the bank filter.

[0020] In one exemplary instance, the second aquifer may be selected from any one or more of the following: porous aquifers and bedrock fracture aquifers.

[0021] Based on the origin of the fractures, bedrock fracture aquifers can be selected from any one or more of the following: tectonic fracture aquifers (including joints, faults, and tectonic fracture zones), weathering fracture aquifers (including weathering joints and fracture zones), and diagenetic fracture aquifers (including interlayer fractures, primary joints, and shrinkage fractures). Tectonic fracture aquifers often form water-conducting fracture zones, which can be the main water-bearing sections and concentrated runoff channels. Weathering fracture aquifers have limited development depth and large seasonal variations in water volume, often constituting unconfined groundwater. Diagenetic fracture aquifers typically have limited self-storage capacity and often connect with fractures of other origins to form hydrologically significant aquifers.

[0022] According to lithological classification, bedrock fissure aquifers can be selected from any one or more of the following: fissure aquifers of igneous rocks (such as granite, basalt, and diorite), fissure aquifers of metamorphic rocks (such as gneiss, quartzite, marble, and slate), fissure aquifers of non-soluble sedimentary rocks (such as clastic rocks, including sandstone, conglomerate, and mudstone; and other rock types, including some siliceous rocks), and fissure aquifers of soluble sedimentary rocks (i.e., karst aquifers).

[0023] When multiple secondary aquifers exist, each secondary aquifer can be independently selected from any one of the following: porous aquifers, bedrock fissure aquifers (including karst fissure aquifers).

[0024] In one exemplary instance, when at least one second aquifer exists—that is, when at least one second aquifer exists below the first aquifer—the second aquifer may or may not be connected to the first aquifer. Multiple second aquifers may also be connected or not connected. Water exchange can occur between connected aquifers.

[0025] In this text, when at least one second aquifer exists, and the intake section of the intake well passes through or extends into the recoverable water-rich section of the first aquifer and the at least one second aquifer from the bank filter, the relative positions of the first aquifer and the at least one second aquifer satisfy that the recoverable water-rich section of the first aquifer and the at least one second aquifer can be obliquely penetrated by an inclined intake well at a set angle.

[0026] In the bank filtration system based on inclined intake wells according to this application embodiment, the determination of whether the inclined intake well extends into or through the second aquifer can be made based on the water intake demand, the extractable water volume of the first aquifer, and the presence or absence of the second aquifer. Specifically, when the second aquifer is absent, the inclined intake well extends into the filtration layer at an angle greater than 0° and less than 90° between its axis and the horizontal direction, with the intake section of the well extending into the first aquifer from the bank filtration. When the second aquifer exists, and the extractable water volume of the first aquifer meets the water intake demand, the inclined intake well extends into the filtration layer at an angle greater than 0° and less than 90° between its axis and the horizontal direction, with the intake section extending only into the first aquifer from the bank filtration to collect and extract water from the first aquifer, thus satisfying the water intake requirements. When at least one second aquifer exists, and the extractable water volume of the first aquifer cannot meet the water intake demand, the inclined intake well extends toward the filter layer at an angle greater than 0° and less than 90° between the well shaft axis and the horizontal direction. The intake section of the intake well passes through or extends into the extractable water-rich section of the first aquifer and at least one second aquifer from the bank filter, so as to collect water from at least one second aquifer based on the extractable water volume of the first aquifer, increase the amount of extractable water, meet the water intake demand, and the number of second aquifers can be determined according to the water intake demand. That is, the higher the water intake demand, the more second aquifers the intake section of the intake well passes through, so as to collect enough water to meet the water intake demand.

[0027] In the bank filtration system based on inclined intake wells of this application embodiment, the water intake ratio of the inclined intake well to the first aquifer and the at least one second aquifer can be adjusted according to the influence of season and region on the available water volume of different aquifers, as well as water quality requirements. Since the water in the second aquifer has slower water circulation and potentially higher water quality risks compared to the first aquifer with better water quality and faster water renewal from the bank filtration, it is preferable to increase the water intake ratio from the first aquifer from the bank filtration when higher water quality requirements are required.

[0028] The shore filtration system based on an inclined intake well in this application embodiment extends the horizontal projection length of the intake well by designing and constructing it. According to Darcy's Law (Q = K × A × i, where Q is the seepage flow rate, representing the volume of water passing through the cross-section of the porous medium per unit time, unit: m³),... 3 / d; K is the permeability coefficient, unit: m / d; A is the cross-sectional area of ​​the water flow, representing the cross-sectional area of ​​the medium perpendicular to the water flow direction, unit: m². 2 ; i is the hydraulic gradient, which is equal to the head loss per unit distance along the seepage path. The seepage flow of groundwater into the intake well is proportional to the cross-sectional area of ​​the water passage. Therefore, the inclined intake well creates a larger effective water collection cylinder range in the target aquifer, increasing the water output of a single well. Furthermore, when an inclined intake well simultaneously passes through or extends into the exploitable water-rich section of the first aquifer from the bank filter and at least one second aquifer located below it, it can not only collect water from the lateral seepage of the river (i.e., water from the first aquifer of the bank filter), but also extract water from the second aquifer, increasing the total water intake and effectively improving the system's water intake and stability. In addition, due to its larger effective water collection cylinder range, the inclined intake well can obtain more "fresh water" (high-quality and fast-renewing) from the bank filter compared to a vertical well, thereby increasing the proportion of bank filter replenishment in the total water intake and reducing dependence on the existing "old water" (slow-circulating and potentially high-risk water quality) in the second aquifer. This improves the water quality and sustainability of the water supply from the source, achieving the effect of increasing water intake and optimizing the water source ratio, effectively improving the stability and purification efficiency of the water intake system.

[0029] Furthermore, since inclined water intake wells can extend horizontally, water intake from aquifers located within the ecological red line can be achieved by setting the wellhead outside the ecological red line, away from the surface water bank, with the well shaft axis extending into or through the target aquifer at a predetermined angle. This precisely solves the problem of implementing water intake projects on the surface within the ecological red line, which is either impossible or difficult.

[0030] Therefore, in one exemplary instance, when the target aquifer is located within the ecological red line area, the wellhead of the inclined water intake well is located outside the ecological red line away from the surface water bank (in order to reduce construction distance and difficulty, the wellhead can be located outside the ecological red line but close to it), and the inclined water intake well extends from the wellhead towards the filter layer at an angle greater than 0° and less than 90° between the well shaft axis and the horizontal direction. The water intake section of the water intake well passes through or extends into the exploitable water-rich section of the first aquifer from the bank filter and optionally at least one of the second aquifers located within the ecological red line area.

[0031] In one exemplary instance, the orientation of the inclined water intake well and the angle between the well shaft axis and the horizontal direction are designed based on the following principles: Based on the wellhead location of the inclined water intake well, the location of the first aquifer and the location of the recoverable water-rich section of at least one optional second aquifer, the direction of the inclined water intake well and the angle between the wellbore axis and the horizontal direction are determined so that the inclined water intake well can pass through or extend into the recoverable water-rich section of the first aquifer and at least one optional second aquifer from the wellhead location as far as possible.

[0032] In one exemplary embodiment, the angle between the axis of the inclined water intake well and the horizontal direction can be from 8° to 80°, specifically 8° to 20°, 20° to 30°, 30° to 40°, 40° to 50°, 50° to 60°, 60° to 70°, or 70° to 80°. In another exemplary embodiment, the angle between the axis of the inclined water intake well and the horizontal direction is 9°.

[0033] In one exemplary instance, the surface water can be selected from any of the following: rivers, lakes, reservoirs, etc.

[0034] In one exemplary embodiment, categorized by geometry, the first aquifer and at least one second aquifer from the bank filter can be selected from any one or more of the following: lenticular, strip-shaped, sac-shaped, net-like, cut-shaped, thin-layered, or thick-layered. In one exemplary embodiment, the natural sediments in the filter layer include at least one of a natural soil layer, a sand layer, a gravelly sand layer, and a gravel layer. In one exemplary embodiment, the filter layer is a Quaternary loose layer, for example, comprising a fine sand layer and / or a gravelly sand layer (fine sand interbedded with pebbles).

[0035] In one exemplary instance, the artificial reinforcing medium in the filter layer includes at least one of graded sand, gravel, activated carbon, zeolite, modified clay, porous ceramics, plastic filler, zero-valent iron, and slow-release carbon source.

[0036] In one exemplary instance, in a karst landform area, the filter layer may be selected from at least one of local sand layers (e.g., fine sand layers, silt layers, etc.) with thickness and continuity that meet filtration requirements, gravelly sand layers (e.g., fine sand with pebbles).

[0037] In one exemplary instance, the inclined intake well is located in the intake section (e.g., screen section) of the first aquifer, which is entirely deployed in a natural sediment layer with strong purification capacity or an artificially enhanced filter layer (e.g., sand layer, gravel layer) to avoid the adverse effects of the upper weakly permeable layer on the water intake and water quality.

[0038] In one exemplary instance, the inclined water intake well includes: Cementing pipe: installed on the outermost layer at the top of the inclined water intake well body; Well casing: installed in the middle layer of the inclined water intake well body and connected to the screen pipe; At least one section of screen tube: Each section of screen tube is respectively installed in the first aquifer and optionally at least one water-rich section of the second aquifer of the bank filtration system; Water intake device: installed inside the well shaft.

[0039] Cementing pipes are used to isolate unstable formations and stabilize the wellbore. The type of cementing pipe is not particularly limited in this article, as long as it meets the aforementioned requirements; for example, it can be selected from oil casing, seamless steel pipe, straight seam welded pipe, etc.

[0040] Well casing is used to withstand formation pressure, isolate surface water from the upper layers, and form the main water transport channel from the screen pipe to the surface. The type of cementing pipe is not particularly limited in this article, as long as it meets the aforementioned requirements. For example, it can be selected from seamless steel pipe, welded steel pipe, unplasticized polyvinyl chloride pipe (UPVC pipe), fiberglass pipe, stainless steel pipe, etc. Well casing can also be a well casing string formed by connecting multiple pipe sections sequentially (e.g., by threading, welding, or flange connection).

[0041] Screen pipes are used to allow water to enter the aquifer while blocking sand particles, preventing well blockage. The type of screen pipe is not particularly limited in this paper, as long as it meets the aforementioned requirements. For example, it can be selected from slotted screen pipes, bridge-type filter pipes, mesh-encased filter pipes, gravel-lined filter pipes, and star-shaped filter pipes. A settling pipe can also be installed at the bottom of the screen pipe to collect and contain fine sand particles that enter the well with the water flow from the screen pipe slots, preventing well blockage and protecting the water pump. The type of settling pipe is not particularly limited in this paper, as long as it meets the aforementioned requirements. For example, it can be selected from sealed-bottom settling pipes, settling pipes with sand settling holes, and open-bottom settling pipes. The slots in the screen pipes can be fabricated on-site. The width can be slightly smaller than the sand particle size, usually 1 mm, depending on the bedrock conditions. Considering its pore-forming function, the length is usually 5 cm to 10 cm, evenly distributed on the pipe wall.

[0042] The water intake device includes a water pump, an outlet pipe connected to the water pump, and a power system for controlling the operation of the water pump.

[0043] In one exemplary instance, the shore filtration system based on an inclined intake well may further include a monitoring and control unit, the monitoring and control unit comprising: The monitoring module is used to collect water quality parameters and / or hydrological data of water taken from each aquifer in the water intake well. The water quality parameters include at least one of turbidity, pH value, dissolved oxygen, etc., and the hydrological data includes at least one of water level, water intake flow rate, etc. The control module is communicatively connected to the monitoring module and the water intake device. It receives and analyzes the data collected by the monitoring module, and generates and sends commands to the water intake device to control the water intake rate or start / stop status based on the analysis.

[0044] In one exemplary instance, a bank filtration system based on an inclined intake well, suitable for groundwater intake in karst landform areas, includes: The filter layer includes a Quaternary loose layer consisting of a soil layer (such as a clay layer and a topsoil layer), a fine sand layer, and a gravelly sand layer (a fine sand layer with pebbles). The first aquifer is formed by the filtration layer filtering surface water along the shore. It is located in the Quaternary loose layer within the ecological red line, specifically in the fine sand layer and / or gravelly sand layer (for example, the first aquifer is thin-layered and lenticular in shape). The second aquifer, spatially located below the first aquifer, is the Jurassic Ziliujing Formation (J... 12 z) Aquifers with interlayer and tectonic fractures in the clastic rocks of the Erqiao Formation (T3e) of the Triassic System; the second aquifer is connected to the first aquifer and can exchange water with the first aquifer, slowly releasing water into the first aquifer to play a regulating role. An inclined water intake well is located outside the ecological red line. The inclined water intake well extends from the wellhead to the filter layer at an angle (e.g., 9°) between the well shaft axis and the horizontal direction, which is greater than 0° and less than 90°. The water intake section of the water intake well extends into the first aquifer from the bank filter.

[0045] Secondly, embodiments of the present invention also provide a bank filtration method based on an inclined intake well. This bank filtration method utilizes the bank filtration system described in the first aspect and is suitable for groundwater extraction in karst landform areas, comprising: Water from the first aquifer and at least one of the optional second aquifers in the bank filtration system is collected by the intake section of the inclined intake well and extracted through the water intake device. And by collecting water quality parameters and / or hydrological data from inclined intake wells through a monitoring and control unit, the start-up and shutdown status of the water intake device, the water intake rate, and / or the water intake ratio for different aquifers can be adjusted.

[0046] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," "fixing," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral part; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0047] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0048] Example 1: Bank filtration system based on inclined intake wells and its application and performance verification in karst rivers. (1) Site selection and hydrogeological condition survey This embodiment was located in a river section within a typical karst landform area in southern China, situated within an ecological red line. To address the challenges of highly heterogeneous aquifers in karst regions, low water extraction efficiency of traditional vertical wells, and high water quality risks, a specialized hydrogeological survey was conducted: Completed a 1:5000 scale hydrogeological survey covering an area of ​​15 km². 2 A high-density electrical resistivity tomography (EDT) method was used to lay out exploration lines with a total length of 1200 meters, revealing significant variations in the thickness of the Quaternary overburden within the area.

[0049] Based on a comprehensive assessment of the ecological red line boundaries, the location of usable land, the thickness of the Quaternary gravel layer as interpreted by geophysical exploration, and the drilling depth to reach the target strata, hydrogeological drilling (hole ZK1) was initiated from outside the ecological red line (with a wellhead inclination depth of 0 m). The exploration results clarified the stratigraphic structure (see...). Figure 1 (a) is from top to bottom: ① Quaternary (Q) loose layer (slope distance depth from 0 m to 108.71 m): Slope depth from 0 m to 49.11 m (horizontal elevation from 392.44 m to 384.76 m): Quaternary (Q) reddish-brown clay, topsoil with a small amount of gravel; Slope depth from 49.11 m to 102.53 m (horizontal elevation from 384.76 m to 376.40 m): Quaternary (Q) grayish-brown fine sand; Slope depth from 102.53 m to 108.71 m (horizontal elevation from 376.40 m to 375.43 m): Quaternary (Q) grayish-brown fine sand with pebbles; The grayish-brown fine sand interbedded with pebbles (slope depth from 102.53 m to 108.71 m) is the main aquifer, and it is distributed in thin layers and lenses. Figure 1 The diagram only shows the aquifer section and does not highlight the distribution of the aquifer. The purpose is to help understand the stratigraphic structure and the path of the inclined well. The static water level depth (slope distance depth) is 95.0 m. ②The underlying bedrock is the Jurassic Ziliujing Formation (J 12 z) and the Triassic Erqiao Formation (T3e) clastic rocks, the water-bearing medium is mainly interlayer fractures and tectonic fractures, with weak water-bearing capacity; the underlying bedrock aquifer is connected to the bottom of the aquifer section of the Quaternary gray-brown fine sand interbedded with cobblestones.

[0050] If vertical wells are used in this area, it is difficult to effectively expose and collect the water-bearing sections of the sand layer that are distributed in thin layers and lenses, and the water output is limited due to the water blocking effect of the upper clay layer.

[0051] (2) Shore filtration system based on inclined intake well Design principles for inclined water intake wells: In order to avoid construction within the ecological red line, maximize the exposure and utilization of underground aquifers, and enhance the filtration effect of riverbanks, the wellhead is designed to be located outside the ecological red line, and the water intake section of the inclined well is located in the aquifer. The direction and angle of the inclined borehole are determined by connecting the two points with a straight line, so as to increase the crossing length of the water intake section of the well in the aquifer.

[0052] Key parameters were determined as follows: The wellhead of inclined shaft ZK1 was set outside the ecological red line and closest to the red line (to reduce construction distance and difficulty). The water intake section of the inclined shaft was located in the main water-bearing section (grayish brown fine sand with cobblestones) with an inclination depth of 102.53 m to 108.71 m. The final borehole inclination depth was 108.71 m. The direction of the inclined borehole and the angle between the well shaft axis and the horizontal were determined by connecting the wellhead position and the final borehole position. It was determined that the aquifer would be drilled into the riverbed bank filter layer from the wellhead position at an angle of 9° between the borehole and the horizontal plane.

[0053] In detail, the shore filtration system based on the inclined intake well includes: 1) Filter layer: The natural filtration layer of this system is the aforementioned Quaternary (Q) loose layer, especially the grayish-brown fine sand and grayish-brown fine sand interbedded with pebbles in the section with a slope depth of 49.11 m to 108.71 m. This layer has an average permeability coefficient K=26.25 m / d. Although its water-bearing capacity is relatively weak, it has good physical filtration and adsorption purification capabilities.

[0054] 2) Inclined intake well (ZK1), which extends from the wellhead outside the ecological red line far from the river section at an angle of 9° between the well axis and the horizontal plane into the aquifer below the riverbed after filtration by the filter layer, such as... Figure 1 The hydrogeological columnar section (b) shows the following structure: Cementing pipe: installed in the section with an inclination depth of 0 m to 24.63 m, located in the outermost layer of the water well body, Φ178 mm; Steel pipe well casing: installed in the section with an inclination depth of 0 m to 69.10 m, located in the middle layer of the water well body, Φ146 mm; Steel pipe well casing: installed in the section with an inclination depth of 0 m to 93.10 m, located in the middle layer of the water well body, with a lower slotted screen pipe, Φ127 mm; Slotted screen tubes: installed in the section with an inclination depth of 93.10 m to 108.10 m, with a diameter of 127 mm, forming the main water outlet section; The actual corresponding slope distance depth of the water outlet section is 102.53 m to 108.71 m (horizontal elevation 376.40 m to 375.43 m), which is lower than the static water level burial depth (slope distance depth) of 95.0 m.

[0055] All the above-mentioned pipes are lowered from the wellhead. Pipes with different diameters do not need to be connected, while pipes with the same diameter can be connected by the threads on the pipe itself.

[0056] 3) Water intake equipment: including a submersible pump and an outlet pipe installed in the inclined intake well, with a pump inclination depth of 100m.

[0057] 4) Monitoring and control unit: including a monitoring device for monitoring water level and water intake flow rate; and a control module, which is communicatively connected to the monitoring module and the water intake device, for receiving and analyzing the data collected by the monitoring module, and generating and sending commands to the water intake device to control the water intake rate or start / stop status based on the analysis.

[0058] (3) Verification of hydraulic performance and water purification efficiency After the system was built, the water supply source of the intake well was subjected to δ 2 H-δ 18O isotope analysis confirmed that the water intake of the bank filtration system was supplied by surface water (Chishui River) infiltration at a rate of 66.4% to 84.1%, clarifying that the bank filtration is the main water source supply and purification mechanism, while the underlying bedrock fissure aquifer connected to the bank filtration aquifer mainly plays a regulating and slow-release role.

[0059] After the system was built, pumping tests and long-term water quality monitoring were conducted to verify its effectiveness, as detailed below: 1) Hydraulic performance (water intake capacity): Pumping test: Steady flow pumping was used. Before pumping, the slant depth of the static water level was 95.0 m (horizontal elevation 377.58 m). The pumping equipment was a 100 QJ6-50 submersible pump (pump depth 100 m). The test lasted 25 hours, with a stabilization time of 24 hours and 00 minutes. The slant depth of the dynamic water level was 95.5 m (horizontal elevation 377.68 m), with a drawdown of 0.5 m (vertical 0.1 m). The stable flow rate was 4.3 m³ / h. 3 / h (103.2 m) 3 / d). The estimated maximum inflow of this inclined intake well is 605 m³. 3 / d. This proves that by increasing the cross-sectional area of ​​the water passage in Quaternary aquifers in karst regions with weak water-bearing capacity, a relatively high water extraction efficiency can be achieved.

[0060] 2) Water purification efficiency: Sampling and testing were conducted in accordance with the Technical Specifications for Surface Water Environmental Quality Monitoring (HJ 91.2-2022) and the Technical Specifications for Groundwater Environmental Monitoring (HJ 164-2020).

[0061] Physical indicators: Long-term monitoring shows that the turbidity of the bank-filtered water is significantly reduced, with a turbidity removal rate as high as 96.25% during the high-water season and 65.68% during the low-water season, and the effluent turbidity consistently meets the standards (e.g., Figure 2 (As shown).

[0062] Chemical and nutrient indicators: The average removal rate for total nitrogen (TN) was 95%, and the removal rate for nitrate nitrogen (NO3) was [missing information]. - The average removal rate of -N was 88% (e.g. Figure 3 (As shown).

[0063] Organic and Emerging Pollutants: The system demonstrates significant removal efficiency for multiple organic pollutants detected in water bodies. Regarding emerging pollutants (ECs) of widespread concern, simulation experiments show that the filtration layer of the shore filtration system based on inclined intake wells achieves a removal rate of over 90% for 21 out of 48 ECs (e.g., ...). Figure 4 (As shown).

[0064] Microbiological indicators: The removal rate of pathogenic microorganisms such as total coliforms and total bacterial count reaches 60% to 100%, effectively ensuring biosafety (e.g., Figure 5 (As shown).

[0065] In summary, this embodiment, based on real exploration, well completion, and test data, fully demonstrates the applicability and superiority of the bank filtration system based on inclined wells in karst landform areas. The bank filtration system in this embodiment, through a wellbore design with a 9° inclination, effectively increases the exposure length in the target aquifer (Quaternary sand layer), thereby achieving a considerable water yield in weakly water-rich strata (estimated maximum yield of 605 m³). 3 ( / d). At the same time, it makes full use of the riverbank strata as a natural filter layer, achieving efficient and stable removal of turbidity, nutrients, organic pollutants and microorganisms, providing an innovative and reliable technical solution for solving the problem of obtaining high-quality water sources in karst areas.

[0066] Comparative Example A vertical well was constructed in the river section outside the ecological red line of this area, with a final vertical depth of 50.19 m. The geological structure is as follows: Vertical depth from 0 m to 17.10 m: Quaternary (Q) reddish-brown clay, sandy clay with a small amount of gravel; Vertical depths range from 17.10 m to 26.74 m: Middle and Lower Jurassic Ziliujing Formation (J 1-2 z) Purplish-red sandy mudstone; Vertical depths range from 26.74 m to 35.01 m: Middle and Lower Jurassic Ziliujing Formation (J 1-2 z) Grayish-green sandstone; Water was first encountered at a vertical depth of 26.74 m, and the main water-producing section of the borehole is from a vertical depth of 26.74 m to 35.01 m.

[0067] The maximum actual water inflow of this vertical well is 5 m³. 3 The water level recovers slowly, requiring 27 hours. Therefore, the estimated maximum extraction volume, based on the data from this pumping operation, is approximately 5 m³. 3 / d. According to the "Groundwater Quality Standard" (GB14848-2022), the water extracted from this vertical well is classified as Class III water.

[0068] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A shore filtration system based on an inclined intake well, characterized in that, The shore filtration system is suitable for groundwater extraction in karst landform areas, including: Filtering layers, including natural sediments and / or artificial reinforcing media on the surface waterfront; The first aquifer is formed by the filtration layer filtering surface water from the shore. At least one of the optional second aquifers is located spatially below the first aquifer; An inclined intake well extends toward the filter layer at an angle greater than 0° and less than 90° between the well shaft axis and the horizontal direction. The intake section of the intake well passes through or extends into the exploitable water-rich section of the first aquifer and optionally at least one second aquifer from the bank filter.

2. The shore filtration system according to claim 1, characterized in that, The second aquifer is selected from any one or more of the following: porous aquifers and bedrock fissure aquifers; Optionally, when multiple second aquifers exist, each of the multiple second aquifers is independently selected from any one of porous aquifers and bedrock fracture aquifers; and / or According to the classification of fracture origin, the bedrock fractured aquifer is selected from any one or more of the following: tectonic fractured aquifer, weathering fractured aquifer, and diagenetic fractured aquifer; and / or When the second aquifer of at least one of the above-mentioned aquifers is present, the second aquifer may be connected to or not connected to the first aquifer; the multiple second aquifers may be connected to or not connected to each other.

3. The shore filtration system according to claim 1, characterized in that, When at least one second aquifer exists, and the intake section of the intake well passes through or extends into the recoverable water-rich section of the first aquifer and the at least one second aquifer from the bank filter, the relative positions of the first aquifer and the at least one second aquifer satisfy that the recoverable water-rich section of the first aquifer and the at least one second aquifer can be obliquely penetrated by an inclined intake well at a set angle.

4. The shore filtration system according to claim 1, characterized in that, When the target aquifer is located within the ecological red line area, the wellhead of the inclined water intake well is located outside the ecological red line away from the surface water bank, and the inclined water intake well extends from the wellhead to the filter layer at an angle greater than 0° and less than 90° with the axis of the well shaft and the horizontal direction. The water intake section of the water intake well passes through or extends into the exploitable water-rich section of the first aquifer from the bank filter and at least one of the optional second aquifers located within the ecological red line area. Optionally, the wellhead of the inclined water intake well is located outside the ecological red line but close to it.

5. The shore filtration system according to claim 1, characterized in that, The direction of the inclined water intake well and the angle between the well shaft axis and the horizontal direction are designed based on the following principles: Based on the wellhead location of the inclined water intake well, the location of the recoverable water-rich section of the first aquifer and at least one of the optional second aquifers, the direction of the inclined water intake well and the angle between the wellbore axis and the horizontal direction are determined so that the inclined water intake well can pass through or extend into the recoverable water-rich section of the first aquifer and at least one of the optional second aquifers from the wellhead location as far as possible. Optionally, the angle between the axis of the inclined water intake well and the horizontal direction is 8° to 80°, and can be selected as 8° to 20°, 20° to 30°, 30° to 40°, 40° to 50°, 50° to 60°, 60° to 70° or 70° to 80°.

6. The shore filtration system according to any one of claims 1 to 5, characterized in that, The surface water is selected from any one of rivers, lakes, and reservoirs; and / or According to their geometric shapes, the first aquifer and at least one second aquifer from the shore filter are each selected from any one or more of the following: lenticular, strip-shaped, sac-shaped, mesh-like, cut-shaped, thin-layered, or thick-layered; and / or In the filter layer, the natural sediments include at least one of a natural soil layer, a sand layer, a gravelly sand layer, and a gravel layer; optionally, the natural sediments include a natural soil layer, a sand layer, and a gravelly sand layer; and / or The filter layer is selected from at least one of sand layers and gravelly sand layers that are localized in karst landform areas and have a thickness and continuity that can meet the filtration requirements. The artificial reinforcing medium includes at least one of graded sand, gravel, activated carbon, zeolite, modified clay, porous ceramics, plastic filler, zero-valent iron, and slow-release carbon source; and / or The inclined intake wells are located in the intake section of the first aquifer, which is entirely deployed in a natural sediment layer or an artificially enhanced filter layer with strong purification capabilities.

7. The shore filtration system according to any one of claims 1 to 5, characterized in that, The inclined water intake well includes: Cementing pipe: installed on the outermost layer at the top of the inclined water intake well body; Well casing: installed in the middle layer of the inclined water intake well body and connected to the screen pipe; At least one section of screen tube: each section of screen tube is respectively installed in the first aquifer and optionally at least one second aquifer in the water-rich section of the bank filtration system; Water intake device: installed inside the well shaft; Optionally, the water intake device includes a water pump, a water outlet pipe connected to the water pump, and a power system for controlling the operation of the water pump.

8. The shore filtration system according to any one of claims 1 to 5, characterized in that, The shore filtration system based on the inclined intake well also includes a monitoring and control unit, comprising: The monitoring module is used to collect water quality parameters and / or hydrological data of water taken from each aquifer in the water intake well. The water quality parameters include at least one of turbidity, pH value and dissolved oxygen, and the hydrological data includes at least one of water level and water intake flow rate. The control module is communicatively connected to the monitoring module and the water intake device. It receives and analyzes the data collected by the monitoring module, and generates and sends commands to the water intake device to control the water intake rate or start / stop status based on the analysis.

9. The shore filtration system according to claim 1, characterized in that, The shore filtration system is suitable for groundwater extraction in karst landform areas, including: The filter layer includes a Quaternary loose layer consisting of a soil layer, a fine sand layer, and a gravelly sand layer; The first aquifer is formed by the filtration layer filtering surface water along the shore, and is located in the Quaternary loose layer within the ecological red line, consisting of fine sand and / or gravelly sand layers. The second aquifer is located spatially below the first aquifer and is an interlayer and tectonic fracture aquifer in the clastic rocks of the Jurassic Ziliujing Formation and the Triassic Erqiao Formation; the second aquifer is connected to the first aquifer. An inclined water intake well is located outside the ecological red line. The inclined water intake well extends from the wellhead towards the filter layer at an angle greater than 0° and less than 90° between the well shaft axis and the horizontal direction. The water intake section of the water intake well extends into the exploitable water-rich section of the first aquifer from the bank filter.

10. A shore filtration method based on an inclined intake well, characterized in that, The bank filtration method, utilizing the bank filtration system as described in any one of claims 1 to 9, is suitable for groundwater extraction in karst landform areas, and includes: Water from the first aquifer and at least one of the optional second aquifers in the bank filtration system is collected by the intake section of the inclined intake well and extracted through the water intake device. And by collecting water quality parameters and / or hydrological data from inclined intake wells through a monitoring and control unit, the start-up and shutdown status of the water intake device, the water intake rate, and / or the water intake ratio for different aquifers can be adjusted.

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