Method for constructing near-natural ecological riverbed

Abstract

The present application relates to a kind of near natural ecological riverbed construction method.The present application is suitable for water ecological restoration technical field.The technical problem to be solved by the present application is to provide a kind of near natural ecological riverbed construction method.The technical scheme adopted by the present application is: a kind of near natural ecological riverbed construction method, characterized in that: S1, based on the original topographic survey data in the present situation revetment of both sides, identify riverbed element, and outline each riverbed element form;S2, based on each riverbed element form identified and outlined in step S1;S3, based on step S2 to establish hydrodynamic model;S4, if step S3 result does not satisfy the requirement, then return to step S2;S5, set ecological protection measures to each riverbed element, and construct ecological riverbed;S6, based on each riverbed element after setting ecological protection measures, establish hydrodynamic model;S7, if step S6 analysis result shows that ecological riverbed construction can not satisfy the requirement of flood discharge, then return to step S5 and optimize ecological protection measures setting.

Description

Technical Field

[0001] This invention relates to a method for constructing near-natural ecological riverbeds. It is applicable to the field of aquatic ecosystem restoration technology. Background Technology

[0002] Natural rivers are meandering, with a sinusoidal coefficient typically not less than 1.3. Their cross-sections show a narrow channel and wide riverbeds, while their longitudinal sections feature alternating deep pools and shallow banks. Urbanization has led to the occupation of vast amounts of riverbank land. To meet flood control requirements, straightened rectangular or trapezoidal cross-sections are often adopted, along with rigid revetments and riverbeds. This alters the naturally porous structure of the banks and riverbed, damaging aquatic animal habitats and consequently impacting the healthy development of the ecosystem.

[0003] Conventional ecological river channel construction primarily focuses on ecological bank restoration or localized habitat improvement. This includes techniques such as riprap, pine piles, gabions, and eco-concrete for riverbank protection, and habitat improvement techniques for riverbeds such as deep pools / shoals, boulders, and overflow weirs. Furthermore, these ecological measures often fail to fully utilize naturally formed topographical conditions. For the ecological transformation of existing hard revetments, demolition and reconstruction or hard revetment modification are frequently employed, with little involvement in ecological riverbed construction.

[0004] In summary, existing ecological river construction focuses on improving the habitat of riverbanks, riverbeds, or local areas. For rivers with existing hard revetments on both sides, it fails to establish ecological riverbeds while preserving the original hard revetments, and therefore fails to propose a systematic governance plan. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for constructing a near-natural ecological riverbed, addressing the aforementioned problems.

[0006] The technical solution adopted in this invention is: a method for constructing a near-natural ecological riverbed, characterized in that:

[0007] S1. Based on the original topographic measurement data within the existing revetments on both sides, identify riverbed elements and delineate the morphology of each riverbed element;

[0008] S2. Based on the morphology of each riverbed element identified and outlined in step S1, adjust the outline of each riverbed element according to the theory of meandering river channels to make the outline of each riverbed element more natural.

[0009] S3. Based on the riverbed elements adjusted in step S2, establish a hydrodynamic model and calculate the water depth and velocity distribution under the influence of a 100-year flood flow.

[0010] S4. If the calculation result of step S3 shows that the flood control requirements are not met, return to step S2 to readjust the outline of each riverbed element until the calculation result shows that the flood control requirements are met.

[0011] S5. Implement ecological protection measures for each riverbed element and construct an ecological riverbed to ensure the lateral ecological connectivity and longitudinal continuity of the river.

[0012] S6. Based on the riverbed elements after the implementation of ecological protection measures, establish a hydrodynamic model to analyze the water level and velocity distribution under channel flow, floodplain flow and flood flow.

[0013] S7. If the analysis results of step S6 indicate that the construction of the ecological riverbed cannot meet the flood control requirements, then return to step S5 to optimize the ecological protection measures until the analysis results indicate that the construction of the ecological riverbed can meet the flood control requirements.

[0014] The aforementioned ecological protection measures for each riverbed element include:

[0015] The riverbed elements include the main channel and the beach. The main channel is protected on both sides by coconut net plant rolls, which are plant planting bases formed by wrapping planting soil with coconut nets. The beach is laid with coconut nets, forming an integral structure with the coconut net plant rolls.

[0016] The aforementioned ecological protection measures for each riverbed element include:

[0017] The riverbed elements include the main channel, and the main channel riverbed consists of, from bottom to top, the original soil layer, the clay layer, the gravel layer, and the pebble layer.

[0018] The aforementioned ecological protection measures for each riverbed element include:

[0019] The riverbed elements include the main channel, on which several stone beam weirs are set. The stone beam weirs are constructed of stacked stones and are arc-shaped structures convex upstream.

[0020] The spacing of the stone beam weirs is determined based on the weir height / riverbed bottom slope.

[0021] The aforementioned ecological protection measures for each riverbed element include:

[0022] The riverbed elements include sandbars, which are based on gabions and fixed to the riverbed with pine piles, and the sides are sloped with riprap. The top of the gabions is covered with coconut netting and vegetation rolls, which are tied and fixed to the gabions.

[0023] The aforementioned ecological protection measures for each riverbed element include:

[0024] The riverbed elements include groynes, which are constructed of pebbles, with their bottoms buried in the riverbed to a depth not less than the maximum scour depth; their tops are 20-40 cm above the normal water level and extend to connect with the floodplain.

[0025] The head of the groyne extends into the main channel, pointing upstream, with its axis forming an angle of 20 to 40 degrees with the main channel.

[0026] The beneficial effects of this invention are as follows: Based on original topographic surveys, this invention identifies riverbed elements such as the main channel, deep pools, and side beaches formed under the action of natural water flow. It adjusts the contours of each riverbed element, establishes a hydrodynamic model, and then optimizes and adjusts the contours of each riverbed element based on the model calculation results, completing the construction of a near-natural ecological river channel. Subsequently, ecological protection measures are set up, a hydrodynamic model is established, and the layout of ecological protection measures is optimized based on the model analysis results, ensuring the stability of the overall riverbed morphology during flood season and achieving habitat diversity. This invention can construct ecological riverbeds between hard revetments, forming a systematic river habitat restoration technology that preserves the original hard revetments. Attached Figure Description

[0027] Figure 1 The flowchart is for an example.

[0028] Figure 2 This is a schematic diagram of riverbed element identification in the embodiment.

[0029] Figure 3 This is a schematic diagram of the riverbed topography shaping in the embodiment.

[0030] Figure 4 This is a schematic diagram of water level and flow velocity distribution under a 100-year return period flow rate in the example.

[0031] Figure 5 This is a schematic diagram of the structure of the main channel, beach, and riverbed protection in the embodiment.

[0032] Figure 6 This is a schematic diagram of the stone beam weir arrangement in the embodiment.

[0033] Figure 7 This is a schematic diagram of the sandbar structure in the embodiment.

[0034] Figure 8 This is a schematic diagram of the groynes in the embodiment.

[0035] Figure 9 This is a plan view of the groynes in the embodiment.

[0036] Figure 10 The water level calculation for the channel flow, floodplain flow, and flood flow (once in a hundred years) in the example is shown.

[0037] Figure 11 The flow velocity calculations are performed for the channel flow, floodplain flow, and flood flow (once in a century) in the examples.

[0038] 11. Existing bank protection; 12. Main channel; 13. Beach; 14. Sandbar; 15. Deep pool; 16. Backwater bay; 17. Groynes; 21. Coconut netting; 22. Coconut netting; 24. Original soil layer; 25. Clay layer; 26. Gravel layer; 27. Pebble layer; 41. Stone beam weir; 141. Gabion; 142. Pine piles; 143. Rockfill; 171. Pebbles; 172. Groynes axis; 173. Angle between axis and main channel. Detailed Implementation

[0039] like Figure 1 As shown, this embodiment is a method for constructing a near-natural ecological riverbed, including the following steps:

[0040] S1. Based on the original topographic measurement data within the existing revetments on both sides, identify riverbed elements and delineate the morphology of each riverbed element.

[0041] like Figure 2 As shown, taking typical area 1 and typical area 2 as examples, based on the original topographic measurement data of the existing revetment on both sides, various riverbed elements are identified, including the main channel, beach, sandbar, deep pool and other elements naturally formed by the existing riverbed under the long-term water flow, and the morphology of each riverbed element is initially outlined.

[0042] S2. Based on the morphology of each riverbed element identified and outlined in step S1, adjust the outline of each riverbed element according to the theory of meandering river channels to make the outline of each riverbed element more natural.

[0043] Step S2 aims to identify the outlined shape through riverbed elements, determine the main channel shape based on the theory of meandering river channels, and connect riverbed elements such as beaches, sandbars, and deep pools to make the outlines of the main channel, beaches, sandbars, and deep pools more natural.

[0044] like Figure 3 As shown, in typical area 1, the deep pool located outside the main channel is connected to the main channel, forming a backwater bay. The bottom elevation of the backwater bay is lower than that of the main channel. The backwater bay can provide a refuge for aquatic animals during the flood season, and can also retain a certain amount of water during the dry season to ensure the basic water source for aquatic organisms.

[0045] In typical area 2, the sandbars near the beach connect with the beach to form groynes. These groynes promote siltation on the upstream side of the groynes, forming shallow water areas, and provide amphibious habitats.

[0046] S3. Based on the riverbed elements adjusted in step S2, establish a hydrodynamic model and calculate the water depth and velocity distribution under the influence of a 100-year flood flow.

[0047] This embodiment establishes an HEC-RAS hydrodynamic model to calculate the water depth and velocity distribution in the main channel and floodplain under the influence of a 100-year flood flow (see...). Figure 4 ).

[0048] S4. If the calculation result of step S3 shows that the flood control requirements are not met, return to step S2 to readjust the outline of each riverbed element until the calculation result shows that the flood control requirements are met.

[0049] In this embodiment, after the riverbed topography shaped in step S2 meets the flood control requirements, the outlines of the main channel, beaches, sandbars, deep pools, etc. are determined, and the subsequent steps are carried out; if the flood control requirements are not met, it is necessary to return to S2 to readjust the riverbed topography.

[0050] S5. Implement ecological protection measures for each riverbed element to construct an ecological riverbed, thereby ensuring the lateral ecological connectivity and longitudinal continuity of the river.

[0051] In this example, based on the requirements of erosion resistance and ecology, ecological protection measures such as main channel, beach, sandbar, and deep pool are set up. These ecological protection measures are mainly made of permeable, flexible and erosion-resistant materials to ensure the lateral ecological connectivity and longitudinal continuity of the river.

[0052] like Figure 5 As shown, the main river channel is protected by coconut fiber plant rolls. These plant rolls are plant bases formed by wrapping planting soil with coconut fiber, which helps to create a joint load-bearing structure between the plant and the soil, enhancing erosion resistance. The riverbanks are also covered with coconut fiber, forming an integrated structure with the coconut fiber plant rolls.

[0053] In this embodiment, the main channel riverbed consists of a soil layer, a clay layer, a gravel layer, and a pebble layer from bottom to top, which not only ensures the ecological requirements of being porous, but also has the functions of water storage and erosion resistance.

[0054] like Figure 6 As shown, the main riverbed erosion control measure in this example is the use of stone beam weirs. These weirs are constructed of stacked stones, forming an arc-shaped structure convex upstream, with a height of 0.3m. The top of the weir is aligned with the normal water level, creating a certain amount of backwater and resulting in a diverse flow pattern alternating between slow and rapid currents. Several stone beam weirs are placed on the main channel riverbed. The spacing between the weirs is determined based on the weir height / riverbed slope. Therefore, where the riverbed slope is larger, the stone beam weirs are spaced closer together and arranged more densely, while conversely, they are spaced further apart and arranged more sparsely.

[0055] like Figure 7 As shown, in this embodiment, the sandbar is based on gabions and fixed to the riverbed with pine piles, and the sides are sloped with riprap; coconut netting is installed on the top of the gabions and tied to the gabions for fixation.

[0056] like Figure 8 and Figure 9As shown, in this embodiment, the groynes are constructed of pebbles, with the bottom buried in the riverbed to a depth not less than the maximum scour depth; the top is 20-40cm above the normal water level and extends to connect with the floodplain. The head of the groynes extends into the main channel, pointing upstream, with its axis forming an angle (173) of 20-40° with the main channel.

[0057] S6. Based on the riverbed elements after the implementation of ecological protection measures, establish a hydrodynamic model to analyze the water level and velocity distribution under channel discharge, floodplain discharge, and flood discharge (see...). Figure 10 , 11 ).

[0058] S7. If the analysis results of step S6 indicate that the construction of the ecological riverbed cannot meet the flood control requirements, then return to step S5 to optimize the ecological protection measures until the analysis results indicate that the construction of the ecological riverbed can meet the flood control requirements.

[0059] This embodiment, by setting up ecological protection measures for the main channel, beaches, sandbars, and deep pools, can ensure the stability of the riverbed and bank protection during flood season. It exhibits diverse flow patterns with alternating deep pools and shallow beaches, and alternating slow and fast currents under both channel flow and floodplain flow, resulting in good ecological performance.

Claims

1. A method for constructing a near-natural ecological riverbed, characterized in that: S1. Based on the original topographic measurement data within the existing revetments on both sides, identify riverbed elements and delineate the morphology of each riverbed element; S2. Based on the morphology of each riverbed element identified and outlined in step S1, adjust the outline of each riverbed element according to the theory of meandering river channels to make the outline of each riverbed element more natural. S3. Based on the riverbed elements adjusted in step S2, establish a hydrodynamic model and calculate the water depth and velocity distribution under the influence of a 100-year flood flow. S4. If the calculation result of step S3 shows that the flood control requirements are not met, return to step S2 to readjust the outline of each riverbed element until the calculation result shows that the flood control requirements are met. S5. Implement ecological protection measures for each riverbed element and construct an ecological riverbed to ensure the lateral ecological connectivity and longitudinal continuity of the river. S6. Based on the riverbed elements after the implementation of ecological protection measures, establish a hydrodynamic model to analyze the water level and velocity distribution under channel flow, floodplain flow and flood flow. S7. If the analysis results of step S6 show that the construction of the ecological riverbed cannot meet the flood control requirements, then return to step S5 to optimize the ecological protection measures until the analysis results show that the construction of the ecological riverbed can meet the flood control requirements. The aforementioned ecological protection measures for each riverbed element include: The riverbed elements include the main channel and the beach. The main channel is protected on both sides by coconut net plant rolls, which are plant planting bases formed by wrapping planting soil with coconut nets. The beach is laid with coconut nets, forming an integral structure with the coconut net plant rolls.

2. The method for constructing a near-natural ecological riverbed according to claim 1, characterized in that, The aforementioned ecological protection measures for each riverbed element include: The riverbed elements include the main channel, and the main channel riverbed consists of, from bottom to top, the original soil layer, the clay layer, the gravel layer, and the pebble layer.

3. The method for constructing near-natural ecological riverbeds according to claim 1, characterized in that, The aforementioned ecological protection measures for each riverbed element include: The riverbed elements include the main channel, on which several stone beam weirs are set. The stone beam weirs are constructed of stacked stones and are arc-shaped structures convex upstream.

4. The method for constructing near-natural ecological riverbeds according to claim 3, characterized in that: The spacing of the stone beam weirs is determined based on the weir height / riverbed bottom slope.

5. The method for constructing near-natural ecological riverbeds according to claim 1, characterized in that, The aforementioned ecological protection measures for each riverbed element include: The riverbed elements include sandbars, which are based on gabions and fixed to the riverbed with pine piles, and the sides are sloped with riprap. The top of the gabions is covered with coconut netting and vegetation rolls, which are tied and fixed to the gabions.

6. The method for constructing a near-natural ecological riverbed according to claim 1, characterized in that, The aforementioned ecological protection measures for each riverbed element include: The riverbed elements include groynes, which are constructed of pebbles, with their bottoms buried in the riverbed to a depth not less than the maximum scour depth; their tops are 20-40 cm above the normal water level and extend to connect with the floodplain.

7. The method for constructing near-natural ecological riverbeds according to claim 6, characterized in that: The head of the groyne extends into the main channel, pointing upstream, with its axis forming an angle of 20 to 40 degrees with the main channel.

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