A process for backfilling marine matrix in bare seagrass bed remediation areas

Abstract

This invention provides a process for backfilling marine sediment in the restoration area of ​​bare seagrass beds, comprising the following steps: S1: Positioning and layout, establishing an axis control network based on the given coordinates of the bare spot pit, and marking the center position and outer contour of the circular restoration pit at sea; S2: Installing a permeable but impermeable anchorage along the outer contour of the bare spot pit; S3: Performing the marine sediment backfilling process in layers; S4: Ensuring elevation and quality control before, during, and after backfilling; S5: Removing the anchorage after backfilling is completed. This process is simple, easy to implement, and has low operational requirements. It can effectively control the amount of suspended sediment. By adopting the backfilling process of this invention, a suitable substrate environment for seagrass growth can be reconstructed in the restoration area of ​​bare seagrass beds, which is of great significance for large-scale restoration of seagrass beds.

Description

Technical Field

[0001] This application relates to the field of marine ecological restoration technology, specifically to a process for backfilling marine matrix in the restoration area of ​​bare seagrass beds. Background Technology

[0002] Seagrass beds are another important marine ecosystem besides mangroves and coral reefs, serving as habitats for many large marine organisms and even mammals. They possess high primary productivity and a strong carbon sequestration capacity. With the increasing intensity of marine development and utilization, global seagrass beds are rapidly declining, making the protection and restoration of seagrass bed ecosystems an urgent priority.

[0003] Factors affecting seagrass growth mainly include temperature, light, salinity, and marine matrix. Among these, natural environmental changes such as sustained high temperatures and continuous rainfall, especially human activities, have created numerous bare patch restoration zones on seagrass beds. These bare patch restoration zones consist of multiple nearly circular pits lacking matrix, indicating damage to the seagrass bed and disruption of its continuity.

[0004] Currently, our unit has completed the first domestic project for backfilling the substrate in the bare seagrass bed restoration area. Based on the project experience, we have proposed a marine substrate production process for the bare seagrass bed restoration area. This process is simple and easy to implement, with low operational requirements, and can effectively control the amount of suspended sediment. By backfilling with the marine substrate produced by this invention, a suitable substrate environment for seagrass growth can be reconstructed in the bare seagrass bed restoration area, which is of great significance for large-scale seagrass bed restoration. Summary of the Invention

[0005] The purpose of this invention is to provide a process for backfilling marine substrate in the seagrass bed bare spot remediation area, aiming to solve the problem that the marine substrate in the seagrass bed bare spot remediation area is no longer suitable for seagrass growth.

[0006] The specific technical solution is as follows:

[0007] A process for backfilling marine matrix in the remediation area of ​​bare seagrass beds includes the following steps:

[0008] S1: Positioning and layout. Based on the given coordinates of the bare crater, perform engineering positioning and establish an axis control network. Mark the center position and outer outline of the circular bare crater to be repaired at sea.

[0009] S2: Install a permeable but impermeable anchorage along the outer contour of the bare pit;

[0010] S3: Layered marine matrix backfilling process;

[0011] S4: Elevation and quality control before, during, and after backfilling;

[0012] S5: Backfilling completed, remove anchoring barriers.

[0013] Preferably, the anchoring enclosure described in step S2 includes an enclosure, clips, and a steel pipe. The enclosure is made of geotextile material, which is permeable to water but impermeable to mud and sand, and its height is at least 50 cm above the seawater depth of the work area at low tide. The clips are characterized by being made of plastic or iron, connecting to the enclosure on one side and fixing the steel pipe on the other. The steel pipe is a seamless steel pipe with an outer diameter of not less than 40 mm, a thickness of not less than 3 mm, and a length of 1.5 to 2 times the height of the enclosure.

[0014] Preferably, a buckle is installed at each of the top and bottom ends of the enclosure, with a set every 0.5m along the length. The steel pipe is secured with the buckles, and the end of the steel pipe is inserted into the marine mud for a length of 0.6~1.0m. The specific insertion length is determined according to the actual construction conditions, but it should be ensured that the enclosure does not shake during construction. The enclosure should be installed 1-2 days before transporting the marine substrate materials.

[0015] Preferably, the substrate backfilling in step S3 should be carried out in layers, with the surface backfilling having a vertical depth of 0-30cm and the bottom backfilling having a vertical depth greater than 30cm. During backfilling, the bottom backfilling should be carried out first, followed by the surface backfilling.

[0016] Preferably, in step S3, the bottom backfilling involves placing mesh bags containing the bottom graded material into the enclosure. Each layer of mesh bags should be no more than 30cm thick and should be placed gently to avoid disturbing the seawater. After each layer is laid, one end of the mesh bag is unsealed, and the substrate is slowly spread evenly in the area. The mesh bag is then retrieved, and the next layer is laid until the design elevation is reached. The surface is then manually sloped according to the design requirements, proceeding slowly from one side to the other. If the slope is lower than the design elevation after sloping, the number of mesh bags should be increased, and the above process repeated until the design elevation and slope are met, at which point sloping should be stopped.

[0017] Preferably, in step S3, after the bottom backfill reaches the design elevation, a 30cm layer is reserved above for the surface substrate filling. The substrate should be gently placed to avoid disturbing the seawater. Once the design elevation is reached, the net bags are retrieved, and the surface is sloped according to the design requirements. Slope brushing should be done slowly from one side to the other. If the slope is lower than the design elevation after brushing, the number of net bags should be increased, and the above process should be repeated until the design elevation and slope are met, at which point the slope brushing should be stopped.

[0018] Preferably, the elevation and quality control before, during, and after backfilling described in step S4 includes: Before backfilling, using a ruler to locate the elevation of the edge and bottom of the bare pit, measuring and recording the average elevation of the pit bottom and edge, and calculating the depth of the substrate to be filled (pit edge elevation - pit bottom elevation). During backfilling, a high-precision depth sounder is used to determine the elevation of the bare pit. If it is lower than the surrounding terrain and elevation, backfilling should continue. If it is higher than the surrounding terrain and elevation, a flat wooden board should be used to level it to make it level with the surrounding area. Timely measurement and control of the layered elevation should be carried out. When leveling the layered backfill, attention should be paid to the overlap of the backfill substrate. At undulating terrain, proper jointing should be done. A dedicated person should be assigned to conduct on-site inspection during backfilling. After backfilling, once all the filling is completed, leveling should be carried out. The leveled substrate surface should be leveled by stringing a line. Any position exceeding the standard height should be leveled according to the line in a timely manner; any position below the standard height should be filled with substrate to level it.

[0019] Preferably, after the anchorage barrier is removed in step S5 and backfilling is completed, the barrier should be left to stand for a period of time until the seawater transparency inside and outside the barrier is the same. The barrier should be removed intermittently and not continuously.

[0020] The beneficial effects of this invention are:

[0021] 1. This invention, through topographic mapping of the bare seagrass patch pits within the seagrass bed restoration area and the setting of substrate layering depths, can accurately recreate the original growth substrate environment of the seagrass in the bare patch restoration area, thereby achieving large-scale restoration of seagrass beds in the bare patch area. Simultaneously, the 0-30cm and 30-60cm backfilling layers meet the substrate depth requirements for seagrass growth while avoiding material waste caused by excessive backfilling. 2. This invention, by employing a permeable but non-permeable anchoring barrier, can prevent the generation of large amounts of suspended sand during substrate placement in the seagrass bed restoration area, thus avoiding adverse effects on the growth of surrounding marine flora and fauna! Attached Figure Description

[0022] Figure 1 Diagram of marine geological backfilling process steps;

[0023] Figure 2 Example: Backfilling process diagram of Type A water-filled puddle matrix in bare spot repair area (surface backfill only);

[0024] Figure 3 Example: Backfilling process diagram of Type B water-filled puddle matrix in bare spot repair area (top layer + bottom layer backfill);

[0025] Figure 4 Schematic diagram of anchored enclosure (elevation + plan) of an example;

[0026] Figure 5 Example: Comparison of seaweed growth before and after substrate application in the bare plate repair area. Detailed Implementation

[0027] The present invention will be further described in detail below with reference to the embodiments. Example

[0028] A seagrass bed bare spot restoration area in a sea area of ​​Hebei.

[0029] In September 2022, using RTK and RTK-enabled drones, engineering positioning and an axis control network were established based on the given coordinates of the bare spot pits. The center position and outer outline of the circular bare spot pits to be repaired were marked at sea. Subsequently, anchorage barriers were installed along the outer outline of the bare spot pits. After the anchorage barriers were installed, the backfill substrate was laid in layers, with a vertical depth of 0-30cm for the surface backfill and a vertical depth greater than 30cm for the bottom backfill. During backfilling, the bottom backfill was carried out first, followed by the surface backfill. After backfilling, the area was left to stand for a period of time until the seawater transparency inside and outside the barriers was consistent, at which point the barriers were removed. In October 2022, seagrass bed transplantation and repair were carried out in the bare spot repair area after substrate backfilling using the counterweight direct insertion method.

[0030] In May 2023, aerial observations using drones showed that after substrate backfilling, the survival rate of seagrass transplanted into all the bare spot pits increased from 0-5% to ≥20%, the seagrass area in sparse areas increased by ≥5%, and the coverage in bare spot areas increased by ≥20%. Comparative Example

[0031] Two unfilled bare spot pits were randomly selected within the seagrass bed bare spot repair area described in the embodiment, and the seagrass bed transplantation and repair were carried out using the same weighted direct insertion method.

[0032] In May 2023, aerial observations using drones showed that the survival rate of seagrass transplanted into bare pits that had not been backfilled with substrate was still 0-5%.

[0033] In summary, by adopting the marine matrix backfilling process for the seagrass bed bare spot restoration area provided by this invention, a suitable bottom environment for seagrass growth can be reconstructed in the seagrass bed bare spot restoration area. At the same time, it is simple and easy to implement, with low operation requirements, and can effectively control the amount of suspended sediment. It will not have a significant impact on the growth and survival of surrounding marine flora and fauna. The survival rate of vegetation on the restored seagrass bed is significantly improved, which makes it possible to restore degraded seagrass beds in surrounding sea areas on a large scale.

Claims

1. A process for backfilling marine matrix in the remediation area of ​​bare seagrass beds, characterized in that, Includes the following steps: S1: Positioning and layout. Based on the given coordinates of the bare crater, perform engineering positioning and establish an axis control network. Mark the center position and outer outline of the circular bare crater to be repaired at sea. S2: Install a permeable but impermeable anchorage along the outer contour of the bare pit; S3: The marine matrix backfilling process is carried out in layers. The backfilling is carried out in layers with a vertical depth of 0-30cm for the surface layer and a vertical depth greater than 30cm for the bottom layer. During backfilling, the bottom layer is carried out first, followed by the surface layer. S4: Elevation and quality control before, during and after backfilling. Before backfilling: Use a ruler to locate the elevation of the edge and bottom of the bare pit, measure and record the average elevation of the bottom and edge of the pit, and calculate the depth of the substrate to be filled. The depth is the elevation of the pit edge minus the elevation of the bottom of the pit. During backfilling: Use a high-precision water depth detector to determine the elevation of the bare pit. If it is lower than the surrounding terrain and elevation, backfilling should continue. If it is higher than the surrounding terrain and elevation, use a flat wooden board to level it so that it is at the same height as the surrounding area. Make timely monitoring and control of the layer elevation. When backfilling and leveling the layers, pay attention to the overlap of the backfill matrix. Make proper joints at undulating terrain. Assign a special person to conduct on-site inspection during backfilling. After backfilling: After all backfilling is completed, level the surface. Use a string line to level the surface. Any areas exceeding the standard height should be leveled according to the line. Any areas below the standard height should be filled with additional substrate to level the surface. S5: Backfilling completed, remove anchoring barriers.

2. The marine matrix backfilling process for the remediation of bare seagrass beds according to claim 1, characterized in that: The anchoring enclosure described in step S2 includes an enclosure, clips, and steel pipes; the enclosure is made of geotextile material, which is permeable to water but not to mud or sand, and its height is at least 50cm higher than the seawater depth of the work area at low tide; the clips are made of plastic or iron, connected to the enclosure on one side and fixed to the steel pipe on the other side; the steel pipes are seamless steel pipes with an outer diameter of not less than 40mm, a thickness of not less than 3mm, and a length of 1.5 to 2 times the height of the enclosure.

3. The marine matrix backfilling process for the remediation of bare seagrass beds according to claim 1, characterized in that: After the anchorage barrier is removed as described in step S5 and backfilling is completed, it should be left to stand for a period of time until the seawater transparency inside and outside the barrier is the same. Then the anchorage barrier should be removed at intervals and not continuously.

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