A groundwater recharge system based on bank slope step filtration

Abstract

The application discloses a groundwater recharge system based on bank slope step filtration, which comprises a water interception and distribution unit, a step filtration unit and an infiltration recharge unit. The water interception and distribution unit is composed of a rubber dam and a distribution pipe, the rubber dam can lift the upstream water level, and river water is introduced into the step filtration unit through the distribution pipe; the step filtration unit comprises two upper and lower filtration zones, both of which are double-layer filtration structures, and the bottom filtration layer is embedded with a perforated pipe; filtered water is discharged into the infiltration recharge unit through the perforated pipe in sequence, and the infiltration recharge unit comprises a shallow recharge layer and a deep recharge well. The raised river water is automatically overflowed to the backwater side embankment slope line filtration unit by the rubber dam, the water quality of the recharge source is improved, and the blockage phenomenon caused by recharge can be effectively prevented; the shallow recharge layer and the deep recharge well can be used to consider the recharge of shallow and deep groundwater, and the groundwater recharge efficiency is significantly improved.

Description

Technical Field

[0001] This invention relates to a groundwater recharge system, and more particularly to a groundwater recharge system based on slope cascade filtration. Background Technology

[0002] As a crucial component of the hydrological cycle and a fundamental element of the ecological and geological environment system, groundwater is an indispensable resource for human survival and development. Globally, over 2 billion people rely on groundwater as their primary water source, and more than half of the world's irrigation water is derived from groundwater. Due to the long-term fact that groundwater extraction rates far exceed natural recharge rates, groundwater levels are continuously declining, leading to a series of serious ecological and geological environmental problems such as wetland degradation, land subsidence, and seawater intrusion, posing a severe threat to regional water security and sustainable development. In recent years, China has successively issued the "Comprehensive Action Plan for the Management of Groundwater Over-extraction in North China" and the "Groundwater Protection Regulations," aiming to strengthen groundwater protection, address groundwater over-extraction, and achieve a balance between extraction and replenishment. Conducting artificial groundwater recharge is a crucial task in achieving this balance and is of great significance for realizing regional sustainable development.

[0003] Currently, using upstream reservoirs and key water diversion projects to replenish downstream rivers for ecological purposes is the simplest and most effective method for groundwater replenishment. However, ecological water replenishment based on natural river channels is severely constrained by the spatial distribution of the receiving area, both horizontally and vertically. Existing technologies can only replenish shallow groundwater and cannot effectively replenish deep groundwater below the aquitard. In addition, the replenishment radius of river channels is relatively limited, confined to areas close to the riverbank. Furthermore, river channel replenishment schemes are rather crude, failing to guarantee the quality of the replenished water source and easily causing blockage of the riverbed infiltration surface, further limiting replenishment efficiency. Summary of the Invention

[0004] Purpose of the invention: The purpose of this invention is to provide a groundwater recharge system based on bank slope cascade filtration that expands the water replenishment space of rivers and improves the quality of the recharged water.

[0005] Technical Solution: This invention proposes a groundwater recharge system based on slope cascade filtration, comprising a water interception and distribution unit, a cascade filtration unit, and an infiltration recharge unit arranged obliquely downwards in sequence; the infiltration recharge unit includes a shallow recharge layer and a deep recharge well; the cascade filtration unit includes several filter strips, each filter strip including a filter layer and a perforated underground pipe that guides the filtered water into the shallow recharge layer; the water interception and distribution unit includes a distribution pipe that introduces river water into the filter layer.

[0006] Preferably, the water interception and distribution unit further includes a rubber dam for raising the upstream water level of the river and allowing the river water to flow into the distribution pipe. The rubber dam can raise the river water level by more than 1.2 meters, ensuring that the upstream water level exceeds the bottom elevation of the distribution pipe.

[0007] Preferably, the water distribution pipe runs through the riverbank slope, has a diameter of 30-50 cm, the distance between adjacent water distribution pipes is greater than 20 meters, and extends obliquely downward towards the back bank.

[0008] Preferably, the cascade filtration unit is located on the back slope of the bank slope and includes a first filtration belt located on the upper right and a second filtration belt located on the lower left. The first filtration belt guides the filtered water into the second filtration belt, and the second filtration belt guides the further filtered water into the shallow replenishment layer. The length of the two filtration belts is reasonably arranged according to the terrain and should not be less than 500 meters.

[0009] Preferably, the first filter belt includes a quartz sand filter layer and a coarse sand filter layer, the coarse sand filter layer being located below the quartz sand filter layer and having a first perforated underground pipe inside; the second filter belt includes a cinder filter layer and a gravel filter layer, the gravel filter layer being located below the cinder filter layer and having a second perforated underground pipe inside.

[0010] Preferably, the filler medium of the quartz sand filter layer is quartz sand with a particle size of less than 0.5 mm and a thickness of 0.4 m; the filler medium of the coarse sand filter layer is quartz sand with a particle size of 0.5 to 1 mm mixed with wood chips and a thickness of 0.6 m; the filler medium of the cinder filter layer is cinder mixed with a small amount of silica and a thickness of 0.4 m; and the filler medium of the gravel filter layer is gravel with a particle size of 0.5 to 3 cm and a thickness of 0.6 m.

[0011] Preferably, the inner diameter of the first and second perforated pipes is 0.2 meters, and the distance between adjacent pipes is less than 3 meters.

[0012] Preferably, the first filter belt and the second filter belt are trapezoidal, and water can permeate through their upper surfaces. The leftmost end of the upper surface is provided with a first water-blocking plate and a second water-blocking plate, respectively. The left end of the first perforated pipe and the second perforated pipe are open, and the right end is closed. The maximum water depth on the surface of the two filter belts is limited to less than 0.3 meters by the water-blocking plates.

[0013] Preferably, the shallow replenishment layer is located at the toe of the slope, and its upper surface is an arc-shaped surface connecting the lower corner of the second filter belt. Its filling medium is pebbles, and the filling thickness decreases from the bank slope to the middle.

[0014] Preferably, the cascade filtration unit and the shallow recharge layer are located in the shallow aquifer, and the deep recharge well is arranged below the shallow recharge layer, with its bottom lower than the top plate of the impermeable layer and extending into the deep aquifer. The top plate of the impermeable layer is located between the shallow aquifer and the deep aquifer and can receive the recharge water filtered by the shallow recharge layer to ensure the recharge of deep groundwater.

[0015] Working principle: The rubber dam can raise the upstream water level, allowing river water to overflow naturally through the distribution pipe to the cascade filtration unit. The cascade filtration unit relies on natural infiltration overflow to perform two-stage filtration of the river water, significantly reducing the concentration of total dissolved solids, nutrients, and metal ions in the filtered water compared to the river water, thus improving the quality of the replenished water and preventing blockage of the infiltration surface. After being filtered by the cascade filtration unit, the river water overflows to the replenishment infiltration unit, first infiltrating into the shallow replenishment layer, and then infiltrating into the deep replenishment well, achieving both shallow and deep groundwater replenishment.

[0016] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: 1. It takes into account both deep and shallow groundwater replenishment, improving the efficiency of river water replenishment; 2. It expands the spatial range of ecological water replenishment in rivers, improves the quality of replenished water, and effectively alleviates the problem of backfill blockage; 3. The terraced filtration unit on the back slope can form a unique riverbank landscape and improve the regional ecological environment. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the present invention. Detailed Implementation

[0018] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0019] like Figure 1 As shown, a groundwater recharge system based on slope cascade filtration includes a water interception and distribution unit 1, a cascade filtration unit 2, and an infiltration recharge unit 3, which are distributed diagonally downwards in sequence.

[0020] The water diversion and distribution unit 1 includes a water distribution pipe 11 for diverting river water and a rubber dam 12. The rubber dam 12 is used to raise the upstream water level of the river by more than 1.2 meters, ensuring that the upstream water level exceeds the bottom elevation of the water distribution pipe 11, allowing river water to flow into the water distribution pipe 11. The water distribution pipe 11 penetrates the riverbank slope 13 and extends towards the back bank with a slope of 0.001. Its diameter is 40 centimeters, and the distance between adjacent water distribution pipes is 25 meters.

[0021] The cascade filtration unit 2 is located on the back slope of the bank slope and includes a first filter belt 21 located on the upper right and a second filter belt 22 located on the lower left. The first filter belt 21 and the second filter belt 22 are trapezoidal. The first filter belt 21 includes a quartz sand filter layer 211 and a coarse sand filter layer 212. The filler medium of the quartz sand filter layer 211 is quartz sand with a particle size of less than 0.5 mm and a thickness of 0.4 m. A first water-proof plate 214 is provided on the left end of its upper surface. The coarse sand filter layer 212 is located below the quartz sand filter layer 211. Its filler medium is quartz sand with a particle size of 0.5 to 1 mm mixed with wood chips and a thickness of 0.6 m. A first perforated underground pipe 213 is provided inside. The second filter zone 22 includes a cinder filter layer 221 and a gravel filter layer 222. The cinder filter layer 221 is filled with cinder mixed with a small amount of silica, and has a thickness of 0.4 meters. A second water-blocking plate 224 is provided on the left end of its upper surface. The gravel filter layer 222 is located below the cinder filter layer 221. Its filler medium is gravel with a particle size of 0.5 to 3 centimeters, and its thickness is 0.6 meters. A second perforated underground pipe 223 is provided inside it. The inner diameter of the first perforated underground pipe 213 and the second perforated underground pipe 223 is 0.2 meters, and the right end is closed. The distance between adjacent underground pipes is 2.5 meters. The maximum water depth on the surface of the two filter zones is limited to below 0.3 meters by the water-blocking plate. The length of the first filter zone 21 and the second filter zone 22 is reasonably arranged to be 500 meters according to the terrain.

[0022] The infiltration recharge unit 3 includes a shallow recharge layer 31 and a deep recharge well 32. The shallow recharge layer 31 is located at the toe of the slope, and its upper surface is an arc-shaped surface connecting the lower corner of the second filter zone 22. Its filling medium is pebbles, and the filling thickness decreases from the bank slope towards the middle. The deep recharge well 32 is arranged below the shallow recharge layer 31 and can receive the recharge water filtered by the shallow recharge layer 31. Its bottom is lower than the top plate 4 of the aquitard and extends into the deep aquifer to ensure the recharge of deep groundwater. The top plate 4 of the aquitard is located between the shallow aquifer and the deep aquifer.

[0023] The water interception and distribution unit 1, the first filter belt 21, the second filter belt 22, and the infiltration and replenishment unit 3 are arranged diagonally downwards in sequence from the upper right to the lower left. The water distribution pipe 11 corresponds to the quartz sand filter layer 211 of the first filter belt 21, the first perforated underground pipe 213 of the first filter belt 21 corresponds to the cinder filter layer 221 of the second filter belt 22, and the first perforated underground pipe 223 of the second filter belt 22 corresponds to the shallow replenishment layer 31 of the infiltration and replenishment unit 3.

[0024] In practical use, the working principles of each part are as follows:

[0025] (1) The rubber dam 12 can be used to raise the upstream water level and allow the river water to overflow naturally to the cascade filtration unit 2 through the water distribution pipe 11;

[0026] (2) The cascade filtration unit 2 relies on natural infiltration overflow to perform two-stage filtration of river water. Each filtration layer significantly reduces the concentration of total dissolved solids, nutrients and metal ions in the filtered water compared to the river water, improves the quality of the replenished water, and prevents the infiltration surface from becoming blocked.

[0027] (3) After being filtered by the cascade filtration unit 2, the river water will overflow through the second perforated underground pipe 223 of the second filter belt 22 to the replenishment infiltration unit 3, first infiltrate into the shallow replenishment layer 31, and then infiltrate into the deep replenishment well 32, so as to achieve both shallow and deep groundwater replenishment.

Claims

1. A groundwater recharge system based on slope cascade filtration, characterized in that, It includes a water interception and distribution unit (1), a cascade filtration unit (2), and an infiltration and replenishment unit (3) arranged diagonally downwards; the infiltration and replenishment unit (3) includes a shallow replenishment layer (31) and a deep replenishment well (32); the cascade filtration unit (2) includes several filter strips, the filter strips include a filter layer and a perforated underground pipe that guides the filtered water into the shallow replenishment layer (31); the water interception and distribution unit (1) includes a water distribution pipe (11) that guides river water into the filter layer and a rubber dam (12); wherein, the rubber dam (12) is used to raise the upstream water level of the river to ensure that the upstream water level exceeds the bottom elevation of the water distribution pipe (11) so that the river water flows into the water distribution pipe (11); the water distribution pipe (11) penetrates the riverbank slope (13) and extends downwards towards the back bank.

2. The groundwater recharge system based on slope cascade filtration according to claim 1, characterized in that, The diameter of the water distribution pipe (11) is 30-50 cm, the distance between adjacent water distribution pipes (11) is greater than 20 meters, and it extends downwards towards the back bank side.

3. A groundwater recharge system based on slope cascade filtration according to claim 1, characterized in that, The stepped filtration unit (2) is located on the back slope of the bank slope and includes a first filtration belt (21) located on the upper right and a second filtration belt (22) located on the lower left. The first filtration belt (21) guides the filtered water into the second filtration belt (22), and the second filtration belt (22) guides the further filtered water into the shallow replenishment layer (31).

4. A groundwater recharge system based on slope cascade filtration according to claim 3, characterized in that, The first filter belt (21) includes a quartz sand filter layer (211) and a coarse sand filter layer (212). The coarse sand filter layer (212) is located below the quartz sand filter layer (211) and has a first perforated underground pipe (213) inside. The second filter belt (22) includes a cinder filter layer (221) and a gravel filter layer (222). The gravel filter layer (222) is located below the cinder filter layer (221) and has a second perforated underground pipe (223) inside.

5. A groundwater recharge system based on slope cascade filtration according to claim 4, characterized in that, The quartz sand filter layer (211) has quartz sand with a particle size of less than 0.5 mm and a thickness of 0.4 m as the filler medium; the coarse sand filter layer (212) has quartz sand with a particle size of 0.5 to 1 mm mixed with wood chips as the filler medium and a thickness of 0.6 m as the filler medium; the slag filter layer (221) has slag mixed with a small amount of silica as the filler medium and a thickness of 0.4 m as the filler medium; and the gravel filter layer (222) has gravel with a particle size of 0.5 to 3 cm and a thickness of 0.6 m as the filler medium.

6. A groundwater recharge system based on slope cascade filtration according to claim 4, characterized in that, The inner diameter of the first perforated pipe (213) and the second perforated pipe (223) is 0.2 meters, and the distance between adjacent pipes is less than 3 meters.

7. A groundwater recharge system based on slope cascade filtration according to claim 4, characterized in that, The first filter belt (21) and the second filter belt (22) are trapezoidal with water passing through the top. The leftmost end of the upper surface is provided with a first water-blocking plate (214) and a second water-blocking plate (224); the right end of the first perforated pipe (213) and the second perforated pipe (223) is a closed end.

8. A groundwater recharge system based on slope cascade filtration according to claim 1, characterized in that, The shallow replenishment layer (31) is located at the toe of the slope, and its upper surface is an arc-shaped surface that connects to the lower corner of the stepped filter unit (2). Its filling medium is pebbles.

9. A groundwater recharge system based on slope cascade filtration according to claim 1, characterized in that, The stepped filtration unit (2) and the shallow replenishment layer (31) are located in the shallow aquifer. The deep replenishment well (32) is arranged below the shallow replenishment layer (31), with its bottom lower than the top plate (4) of the aquitard and extending into the deep aquifer. The top plate (4) of the aquitard is located between the shallow aquifer and the deep aquifer.

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