Ecological restoration method for slow-flow river channel

Abstract

The invention discloses an ecological restoration method for a slow-flow river channel, and relates to the technical field of river restoration. Comprising the following steps: 1) preparing an ecological restoration carrier; 2) measuring the ecological suitability degree of the river bottom sludge; (3) riverway zoning; and 4) ecological restoration of the river channel. According to different survival rates of aquatic plants in a slow-flow river channel with moderate and light pollution, the aquatic plants are divided into different areas, and different ecological management schemes are used in a targeted manner. The survival rate of submerged plant seedlings in the controlled slow-flow river reach is remarkably increased, and about 60% of the riverbed area is covered by submerged plants.

Description

Technical Field

[0001] The invention relates to the technical field of river restoration, and more particularly to an ecological restoration method for a slow-flowing river channel. Background Art

[0002] A river is a comprehensive and complex ecosystem that includes land, plant and animal communities, and water bodies. It has the key functions of regulating water flow, storing water, purifying water to remove harmful substances, and providing habitats for aquatic and terrestrial organisms. Its vegetation characteristics are significantly different from those on both banks, showing a high degree of species diversity. Specifically, in rivers with slow flow rates, silt pollution mainly comes from the deposition of pollutants in the water body. Due to the difference in flow rate, the sediment concentration gradually increases from the center of the river to the two banks, showing a distribution feature of low in the center and high on the shore.

[0003] The current engineering dredging method is not suitable for rivers with moderate to light pollution. It is not only costly, but also seriously interferes with the natural ecological functions of the river, leading to a series of problems such as the river's ecological environment becoming more monotonous, aquatic vegetation being lost, the surrounding ecological chain being broken, biodiversity declining, and the river's self-purification ability being weakened.

[0004] As one of the core technologies of ecological restoration projects, the planting and restoration technology of submerged plants has a significant effect on the treatment, regulation and inhibition of water and sediment pollution and eutrophication. Submerged plants rely on their huge biomass and frequently exchange substances and energy with the environment, building a broad environmental capacity and a powerful natural purification system. This type of plant lives in water throughout its life cycle. Its roots, stems and leaves can effectively absorb nutrients from the water. Its growth process is essentially a process of continuous absorption of nutrients from the water. In addition, microorganisms attached to the rhizosphere of submerged plants can also degrade organic pollutants, thereby continuously improving water quality and promoting the ecological restoration of sediments.

[0005] Therefore, providing a method for ecological restoration of lightly polluted slow-flowing rivers using submerged plants is an urgent problem to be solved by technicians in this field. Summary of the invention

[0006] In view of this, the present invention provides a method for ecological restoration of a slow-flowing river.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] A method for ecological restoration of a slow-flowing river comprises the following steps:

[0009] 1) Preparation of ecological restoration carrier:

[0010] Take bottom sludge from clean water bodies, wrap it with degradable non-woven fabric to form a spherical carrier, make holes evenly on the hemispherical surface, plant submerged plant seedlings, and prepare an ecological restoration carrier;

[0011] 2) Determination of ecological suitability of riverbed silt:

[0012] Place ecological restoration carriers into the river channel, and place 5-10 ecological restoration carriers every 10m along the vertical direction of the center line of the river channel; count the growth of aquatic plants after 7 days;

[0013] 3) River zoning;

[0014] Based on the statistical results of the survival rate of aquatic plants SR, the river is divided into zones, with the placement point of the ecological restoration carrier as the midpoint of the zone and a width of 10m:

[0015] S1: From the river bank to the release point where SR ≤ 25% is close to the river bank;

[0016] S2: 25%<SR≤50% placement point;

[0017] S3: 50%<SR delivery point;

[0018] S4: the release point with SR ≤ 25% on the side close to the centerline of the river to the centerline of the river;

[0019] 4) River ecological restoration:

[0020] Silt covering materials are evenly placed in the S1 area, and then ecological restoration carriers are placed;

[0021] The ecological restoration carrier is placed in the S2 area;

[0022] Submerged plant seedlings are directly placed in the S3 area.

[0023] Furthermore, the diameter of the spherical carrier is 8-12 cm, and the number of submerged plant seedlings planted is 8-10.

[0024] Furthermore, in step 2), the ecological restoration carrier is bound with a fishing line before being released, and the fishing line is connected to a floating ball for positioning on the water surface.

[0025] Furthermore, the submerged plant seedlings are:

[0026] Any one or more of Vallisneria, Dermatophyte, Hydrilla verticillata, and Foxtail algae.

[0027] Furthermore, the composition of the sludge covering material in step 4) is calculated by weight:

[0028] 50 parts of activated carbon sludge, 10 parts of zeolite, 5 parts of calcium peroxide;

[0029] The thickness of the silt covering material is 10-20 cm.

[0030] Furthermore, in step 4), a spur dike is constructed in the S1 area, and silt covering materials are placed in the intervals between the spur dikes.

[0031] Furthermore, the placement density of the ecological restoration carrier in step 4) is 5 / m 2 ;

[0032] The direct placement density of the submerged plant seedlings is 50-100 plants / m 2 ;

[0033] It can be seen from the above technical solution that, compared with the prior art, the beneficial effects of the present invention are:

[0034] The present invention uses different treatment schemes in view of the different survival rates of aquatic plants in slow-flowing rivers with medium or light pollution.

[0035] The S1 area is close to the river bank, the water is shallow, the sun is abundant, and the aquatic plants grow well, which can remove pollutants more effectively. The disadvantages are slow flow rate, easier sedimentation of water pollutants, and too high concentration of pollutants in the bottom silt. Without using engineering dredging, the present invention selects silt covering materials. The covering material can also isolate the riverbed silt with too high pollutant concentration, allowing aquatic plants to grow normally and deal with new pollutants that continue to accumulate.

[0036] Building a spur dike in the S1 area can further slow down the flow speed, slightly increase the sedimentation rate of pollutants in the spur dike area, and help transplanted aquatic plants to deal with pollution. The spur dike can also confine the water, increase the flow speed in the centerline area of ​​the river, and reduce the sedimentation rate of pollutants in the center area of ​​the river.

[0037] The ecological restoration carrier contains pollution-free sludge taken from clean water bodies, which can ensure the survival of aquatic plants in areas S1 and S2. In the S3 area, the light conditions and the concentration of sludge pollutants are balanced, the survival rate of aquatic plants is more than 50%, and submerged plant seedlings can be directly placed for ecological restoration.

[0038] The survival rate of submerged plant seedlings in the slow-flowing river section after treatment by the present invention is significantly improved, with the survival rate in the S1 area reaching 76.7-80%, the survival rate in the S2 area reaching 56.6-70%, and the survival rate in the S3 area reaching 83.3-86.7%. Underwater observation found that about 60% of the riverbed of the slow-flowing river section was covered by submerged plants. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. 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.

[0040] Example 1

[0041] A method for ecological restoration of a slow-flowing river comprises the following steps:

[0042] 1) Preparation of ecological restoration carrier:

[0043] Take bottom sludge from clean water, wrap it with degradable non-woven fabric to form a spherical carrier with a diameter of 10 cm, make 10 holes evenly on the hemispherical surface, plant aquatic plant seedlings in each hole, and prepare an ecological restoration carrier;

[0044] Aquatic plant seedlings are all submerged plants, including Vallisneria, Duckweed, Hydrilla verticillata, and Foxtail algae.

[0045] 2) Determination of ecological suitability of riverbed silt:

[0046] A restoration experiment was conducted in a slow-flowing river section in Guangdong Province. The average width of the river in the test section was 146m. Starting from the west bank of the river, the ecological restoration carrier was placed in the river. Eight ecological restoration carriers (two each of Vallisneria, Dermatophyte, Hydrilla verticillata, and Myriophyllum) were placed every 10m along the vertical direction of the centerline of the river. A total of 14 placements were made. Before placement, the ecological restoration carrier was tied to a fishing line, and the fishing line was connected to a floating ball for positioning on the water surface (if the water flow is fast, the fishing line can also be tied to bricks or other heavy objects to fix the floating ball);

[0047] The experiment was repeated 50m and 100m downstream of the first placement location;

[0048] After 7 days, the growth of aquatic plants was counted. Starting from the west bank of the river, the average survival rate of aquatic plants at different distances from the release points was counted. The results are shown in Table 1.

[0049] Table 1 Average survival rate of submerged plant seedlings at different distances from the release point

[0050]

[0051] The results in Table 1 show that the survival rate of aquatic plants shows a trend of first increasing and then decreasing from the river bank to the center line of the river. The water flow rate near the river bank is slow, water pollutants are more likely to deposit, and the concentration of pollutants in the river bank mud is too high, resulting in a decrease in the survival rate of submerged plant seedlings. As the water flow rate increases, pollutant deposition decreases as it approaches the center line of the river, and the survival rate of submerged plant seedlings increases. The water flow rate near the center line of the river is the highest, pollutant deposition is the least, and the corresponding water body is the deepest. There is insufficient light for submerged plant seedlings, and the survival rate decreases.

[0052] The regions are divided according to the degree of pollution of the silt at the bottom of slow-flowing rivers.

[0053] 3) River zoning;

[0054] Based on the statistical results of the survival rate of aquatic plants SR, the river is divided into zones, with the placement point of the ecological restoration carrier as the midpoint of the zone and a width of 10m:

[0055] S1: From the river bank to the release point where SR ≤ 25% is close to the river bank;

[0056] S2: 25%<SR≤50% placement point;

[0057] S3: 50%<SR delivery point;

[0058] S4: From the release point with SR ≤ 25% on the side close to the river centerline to the river centerline.

[0059] Table 2 Division of treatment areas at different distances from the deployment points

[0060]

[0061] Note: The leftmost S1 area extends to the west bank of the river, and the rightmost S1 area extends to the east bank of the river.

[0062] 4) River ecological restoration:

[0063] A spur dike was built in the S1 area, and silt covering materials were placed in the intervals between the dikes. The composition of the silt covering materials, by mass, is as follows: 50 parts of activated carbon sludge, 10 parts of zeolite, and 5 parts of calcium peroxide. After being dispersed and mixed, they were evenly placed with a thickness of 15 cm. Then, ecological restoration carriers were placed with a density of 5 / m 2 (Vallis, Ceratophyllum, Hydrilla verticillata, and Myriophyllum were randomly mixed, with equal total amounts);

[0064] The ecological restoration carriers are placed in the S2 area with a density of 5 / m 2 (Vallis, Ceratophyllum, Hydrilla verticillata, and Myriophyllum were randomly mixed, with equal total amounts);

[0065] The submerged plant seedlings are directly placed in the S3 area at a density of 50 plants / m 2 .

[0066] When directly placing the seedlings, dig the submerged plant seedlings out of the cultivation mud. The roots are carrying mud, and they are lightly grasped and fixed by hand to facilitate the seedlings to sink to the bottom quickly after being placed in the water.

[0067] After 12 months of ecological management, the ecological suitability of the riverbed mud in the restored river section was measured. Ten ecological carriers were randomly placed in different zones, tied with fishing lines and floating balls for positioning. The placement was repeated 50m and 100m downstream of the first placement. The mean survival rate was calculated 7 days later. The results are shown in Table 3:

[0068] Table 3 Average survival rate of submerged plant seedlings in different zones

[0069] Partition S1 S2 S3 S2 S3 S2 S1 Mean survival rate (%) 76.7 70.0 83.3 56.6 86.7 66.7 80.0

[0070] The results in Table 3 show that after 12 months of treatment, the survival rate of submerged plant seedlings in the slow-flowing river section increased significantly, reaching 76.7-80% in the S1 area, 56.6-70% in the S2 area, and 83.3-86.7% in the S3 area. Underwater observations found that about 60% of the riverbed in the slow-flowing river section was covered by submerged plants.

[0071] Water quality testing shows that the pH value of the water in the slow-flowing river channel restoration area has increased from 6.2 to 6.9, from slightly acidic water to slightly neutral water, the water organic matter removal rate has reached 45%, the turbidity has decreased significantly, the water transparency has increased from 0.9m to 1.3m, the dissolved oxygen concentration has increased from 1.41mg / kg to 2.23mg / kg, the total nitrogen removal rate in the water has reached 18%, the total phosphorus removal rate has reached 32%, and the water pollution phenomenon has been significantly improved.

[0072] 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 ecological restoration of a slow-flowing river, characterized in that: The following steps are involved: 1) Preparation of ecological restoration carrier: Take bottom sludge from clean water bodies, wrap it with degradable non-woven fabric to form a spherical carrier, make holes evenly on the hemispherical surface, plant submerged plant seedlings, and prepare an ecological restoration carrier; 2) Determination of ecological suitability of riverbed silt: Place ecological restoration carriers into the river channel, and place 5-10 ecological restoration carriers every 10m along the vertical direction of the center line of the river channel; count the growth of aquatic plants after 7 days; 3) River zoning; Based on the statistical results of the survival rate of submerged plant seedlings, the river channel is divided into zones, with the placement point of the ecological restoration carrier as the midpoint of the zone and a width of 10m: S1: From the river bank to the release point where SR ≤ 25% is close to the river bank; S2: 25%<SR≤50% placement point; S3: 50%<SR delivery point; S4: the release point with SR ≤ 25% on the side close to the centerline of the river to the centerline of the river; 4) River ecological restoration: A spur dike is constructed in the S1 area, silt covering materials are evenly placed in the intervals between the spur dikes, and then an ecological restoration carrier is placed; The ecological restoration carrier is placed in the S2 area; Submerged plant seedlings are directly placed in the S3 area.

2. A method for ecological restoration of a slow-flowing river according to claim 1, characterized in that: The diameter of the spherical carrier is 8-12 cm, and the number of submerged plant seedlings planted is 8-10.

3. A method for ecological restoration of a slow-flowing river according to claim 1, characterized in that: Step 2) The ecological restoration carrier is bound with a fishing line before being released, and the fishing line is connected to a floating ball for positioning on the water surface.

4. A method for ecological restoration of a slow-flowing river according to claim 1, characterized in that: The submerged plant seedlings are: Any one or more of Vallisneria, Dermatophyte, Hydrilla verticillata, and Foxtail algae.

5. The method for ecological restoration of a slow-flowing river according to claim 1, characterized in that: Step 4) The sludge covering material composition, by mass: 50 parts of activated carbon sludge, 10 parts of zeolite, 5 parts of calcium peroxide; The thickness of the silt covering material is 10-20 cm.

6. The method for ecological restoration of a slow-flowing river according to claim 1, characterized in that: Step 4) constructing a spur dike in the S1 area and placing silt covering materials in the intervals between the spur dikes.

7. The method for ecological restoration of a slow-flowing river according to claim 1, characterized in that: Step 4) The placement density of the ecological restoration carrier is 5 / m 2 ; The direct placement density of the submerged plant seedlings is 50-100 plants / m 2 .

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