Fine flushing and rough supplementing type riverbed substrate habitat restoration method and system for small hydropower station exiting river reach

Abstract

The invention discloses a'fine flushing and coarse supplementing 'type riverbed substrate habitat restoration method and system for a small hydropower station quit river reach, and relates to the field of ecological restoration, and the method comprises the steps: obtaining the hydrologic and geomorphic information of the implemented small hydropower station quit river; key habitat area distribution in the river reach influenced by small hydropower station quitting is determined according to hydrological and landform information, and the matrix particle size condition of the key habitat area and the part and thickness of water flow scouring and silting are determined; determining a riverbed substrate habitat restoration scheme (including pebble supplement, boulder group arrangement, ecological spur dike arrangement and ecological water guide barrage arrangement) by combining the key habitat restoration layout map; simulating the restoration effect based on the riverbed substrate habitat restoration scheme and the hydrodynamic sediment transport model, and adjusting the riverbed substrate habitat restoration scheme according to the simulation result to obtain the optimal riverbed substrate habitat restoration scheme. According to the method, the damaged river reach of river degradation caused by small hydropower station quitting can be recovered, and the natural landform state of the river is recovered.

Description

Technical Field

[0001] The present application relates to the field of ecological restoration, and in particular to a method and system for restoring riverbed bottom habitats in a river section where small hydropower stations have withdrawn from the project by means of a "flushing fine and filling coarse" method. Background Art

[0002] In recent years, with the active promotion of small hydropower cleanup and rectification work, a large number of small hydropower projects in mountainous rivers have been withdrawn, and the dams have been dismantled to restore the vertical connectivity of the upstream and downstream rivers. Although the withdrawal of small hydropower is to restore the natural connectivity of the river and prevent the deterioration of the river's ecological environment, in the process of dismantling the dams, due to the failure to take effective sediment adaptive management measures, the demolition behavior has caused damage to the river habitat in the short term, making it take longer for the river to recover in the subsequent recovery process or even impossible to recover. Summary of the invention

[0003] The purpose of this application is to provide a method and system for restoring the riverbed substrate habitat by "flushing fine and filling coarse" in river sections where small hydropower has been withdrawn, which can reduce the problem of damaged river habitats caused by the withdrawal of small hydropower, restore damaged river sections caused by river degradation due to the withdrawal of small hydropower, and restore the natural landform of the river.

[0004] To achieve the above objectives, this application provides the following solutions:

[0005] In the first aspect, the present application provides a method for riverbed bottom habitat restoration of a river section where small hydropower is withdrawn by “flushing fine and filling coarse”, comprising:

[0006] Obtaining hydrological and geomorphological information of the river channel where small hydropower has been withdrawn; the hydrological and geomorphological information includes basic information of the river channel, riverbed topography within the river section affected by the withdrawal of small hydropower, riverbed matrix particle size distribution map within the river section affected by the withdrawal of small hydropower, and siltation layer distribution map within the river section affected by the withdrawal of small hydropower;

[0007] According to the basic information of the river channel, the hydrodynamic condition judgment method is adopted, based on the hydrodynamic sediment transport model and the accessibility requirements of key habitats for aquatic organisms, to determine the distribution of key habitat areas in the river section affected by the withdrawal of small hydropower, and draw a key habitat restoration layout map;

[0008] Determine the substrate particle size of the key habitat area and the location and thickness of the siltation by water flow according to the key habitat restoration layout map, the riverbed topography map, the riverbed substrate particle size distribution map and the siltation layer distribution map;

[0009] Determine the riverbed bottom habitat restoration plan based on the key habitat restoration layout map, the substrate particle size of the key habitat area, and the location and thickness of the siltation by water flow; the riverbed bottom habitat restoration plan includes a pebble supplement plan, a boulder group layout plan, an ecological spur dike setting plan, and an ecological water diversion weir setting plan;

[0010] Based on the riverbed sediment habitat restoration plan and the hydrodynamic sediment transport model, the restoration effect of the river channel where small hydropower has been withdrawn is simulated, and the riverbed sediment habitat restoration plan is adjusted according to the simulation results to obtain the optimal riverbed sediment habitat restoration plan.

[0011] Optionally, obtain hydrological and geomorphological information of the river channel where small hydropower has been withdrawn, including:

[0012] Obtain basic information on rivers where small hydropower has been withdrawn;

[0013] Determine the location of the river section where the small hydropower station will be withdrawn in the river channel, and determine the impact range of the river section where the small hydropower station will be withdrawn according to the location of the river section where the small hydropower station will be withdrawn in the river channel;

[0014] Within the influence range of the river section where small hydropower is to be withdrawn, riverbed topography mapping, riverbed matrix particle size analysis and silt layer thickness measurement are carried out, and a riverbed topography map, a riverbed matrix particle size distribution map and a silt layer distribution map of the river section affected by the withdrawal of small hydropower are drawn.

[0015] Optionally, according to the position of the river section where the small hydropower station is to be withdrawn in the river channel, determining the impact range of the river section where the small hydropower station is to be withdrawn includes:

[0016] Determine the scope of the reservoir area before the removal of the small hydropower station according to the location of the river section where the small hydropower station will be removed in the river channel and the water level-reservoir capacity curve of the reservoir area;

[0017] According to the position of the small hydropower exit river section in the river channel, determine the longitudinal slope of the downstream river channel, the distribution of stepped riverbed and the gentle slope section of the river channel;

[0018] Determine the impact range of downstream sediment release after the removal of small hydropower stations based on the longitudinal slope of the downstream river channel, the distribution of the stepped riverbed and the gentle slope section of the river channel;

[0019] The impact scope of the river section where the small hydropower station will be withdrawn is determined based on the reservoir area before the small hydropower station is dismantled and the impact scope of downstream sediment release after the small hydropower station is dismantled.

[0020] Optionally, according to the key habitat restoration layout map, the riverbed topography map, the riverbed matrix particle size distribution map and the silt layer distribution map, the matrix particle size of the key habitat area and the location and thickness of the silt scouring by water flow are determined, specifically including:

[0021] According to the key habitat restoration layout map and the riverbed substrate particle size distribution map, the substrate particle size of the key habitat area is evaluated to obtain the substrate particle size situation of the key habitat area;

[0022] According to the key habitat restoration layout map, the riverbed topography map and the silt layer distribution map, the key habitat areas and the location and thickness of the silt to be scoured by water flow are determined.

[0023] Optionally, the key habitat areas include spawning grounds, feeding grounds, wintering grounds and cold-water fish lurking areas.

[0024] Optionally, the pebble supplementation scheme is to supplement pebbles in the area where the particle size of the sediment layer in the convex bank of the river channel is smaller than the set coarse particle size threshold;

[0025] The boulder group layout plan is to set up boulder groups in the wide and shallow parts of the straight river, the water intake of the hydropower station and the flood discharge channel, and use the water flow power to wash away the sediment with a particle size smaller than the set fine particle size threshold;

[0026] The ecological spur dike setting scheme is to set up ecological spur dikes in the concave banks of the river channel, the reservoir area and the local flat river section, and use the water flow power to flush the sediment with a particle size smaller than the set fine particle size threshold;

[0027] The ecological water diversion weir setting plan is to set up ecological water diversion weirs in straight river sections and river bend entrances in streams with slopes less than a set slope threshold, and use water flow dynamics to flush sediment with particle sizes less than a set fine particle size threshold, so that the fine-grained sediment in the riverbed is flushed to both sides of the downstream of the ecological water diversion weir.

[0028] Optionally, the weight of the pebbles supplemented by the pebble supplement scheme is: W s =h c ×S c ×ρ d ×[(1-a) / 0.4-a]; where, W s is the weight of the pebble, h c is the thickness of the sediment layer in the spawning ground, S c is the area of ​​the spawning ground, ρ d is the density of the sediment layer, a is the matrix content in the sediment layer soil sample that meets the particle size range of the spawning ground;

[0029] The particle size of the pebbles supplemented by the pebble supplementation scheme is larger than the set median particle size;

[0030] The roundness of the pebbles supplemented by the pebble supplement scheme is greater than 0.6.

[0031] Optionally, the length and placement angle of the ecological spur dam set in the ecological spur dam setting plan are determined according to the bed-making flow or the design flood flow, and sediment transport simulation is performed based on a hydrodynamic model.

[0032] Optionally, the shape of the ecological water diversion weir provided in the ecological water diversion weir setting scheme is a "V"-shaped or "U"-shaped one opening upstream.

[0033] In the second aspect, the present application provides a riverbed bottom habitat restoration system of the "flushing fine and filling coarse" type in the river section where small hydropower is withdrawn, comprising:

[0034] An information acquisition module is used to acquire hydrological and geomorphological information of a river channel where small hydropower has been withdrawn; the hydrological and geomorphological information includes basic information of the river channel, a riverbed topographic map within the river section affected by the withdrawal of small hydropower, a riverbed matrix particle size distribution map within the river section affected by the withdrawal of small hydropower, and a siltation layer distribution map within the river section affected by the withdrawal of small hydropower;

[0035] A key habitat determination module is used to determine the distribution of key habitat areas in the river section affected by the withdrawal of small hydropower, and draw a key habitat restoration layout map based on the basic information of the river channel, the hydrodynamic condition judgment method, the hydrodynamic sediment transport model and the accessibility requirements of key habitats for aquatic organisms;

[0036] A key habitat analysis module is used to determine the substrate particle size of the key habitat area and the location and thickness of the siltation by water flow according to the key habitat restoration layout map, the riverbed topography map, the riverbed substrate particle size distribution map and the siltation layer distribution map;

[0037] A scheme determination module is used to determine a riverbed bottom habitat restoration scheme based on the key habitat restoration layout diagram, the substrate particle size of the key habitat area, and the location and thickness of the siltation by water flow; the riverbed bottom habitat restoration scheme includes a pebble supplement scheme, a boulder group layout scheme, an ecological spur dike setting scheme, and an ecological water diversion weir setting scheme;

[0038] The scheme adjustment module is used to simulate the restoration effect of the river channel where small hydropower has been withdrawn based on the riverbed sediment habitat restoration scheme and the hydrodynamic sediment transport model, and adjust the riverbed sediment habitat restoration scheme according to the simulation results to obtain the optimal riverbed sediment habitat restoration scheme.

[0039] According to the specific embodiments provided in this application, this application discloses the following technical effects:

[0040] The present application provides a method and system for repairing riverbed bottom habitats in a river section where small hydropower has been withdrawn by "flushing the fine and filling the coarse" type. By analyzing the hydrological and geomorphological information of the river channel where small hydropower has been withdrawn, the key habitat areas in the river section affected by the withdrawal of small hydropower are determined, and the matrix particle size in the key habitat area and the location and thickness of the scouring and silting by water flow are determined. Based on the above analysis results, a riverbed bottom habitat restoration plan is determined. The riverbed bottom habitat restoration plan includes pebble supplementation, boulder group layout, ecological spur dike setting and ecological water diversion weir setting. The restoration effect is simulated based on a hydrodynamic sediment transport model, and the restoration plan is adjusted to form the four optimal plans, thereby repairing the riverbed bottom habitat, reducing the problem of damaged river habitats caused by the withdrawal of small hydropower, and being able to restore the damaged river section degraded by the withdrawal of small hydropower, and restore the natural geomorphological state of the river. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0042] Figure 1 A flow chart of a method for restoring riverbed subsoil habitat by “flushing fine and filling coarse” in a river section where small hydropower is withdrawn, provided in one embodiment of the present application;

[0043] Figure 2 A schematic diagram of the restoration of cross-sectional landform diversity after “flushing and thickening” of a meandering river section;

[0044] Figure 3 This is a cross-sectional diagram of the arrangement of boulders at the water intake of the original power station;

[0045] Figure 4 This is a plan view of the arrangement of boulders at the water intake of the original power station;

[0046] Figure 5 Schematic diagram of setting up boulder "thinning" for wide and shallow river sections;

[0047] Figure 6 This is a schematic diagram of the structure of the U-shaped ecological water diversion weir;

[0048] Figure 7 A schematic diagram of the terraced landform formed by “flushing out fine water and supplementing coarse water” in the straight river section;

[0049] Figure 8 A schematic diagram of the overall layout of a riverbed habitat restoration solution provided in one embodiment of the present application;

[0050] Fig. 9This is a functional module diagram of a riverbed bottom habitat restoration system of the "flushing fine and filling coarse" type for a river section where small hydropower is withdrawn, according to an embodiment of the present application.

[0051] Description of reference numerals:

[0052] 1- released sediment cover layer in the reservoir area, 2- deep pool, 3- pebbles, 4- shallows, 5- boulders, 6- original water inlet of hydropower station, 7- scouring pit, 8- bottom rocks, 9- stones larger than other wave crests, 10- width of ecological water diversion weir, 11- length of ecological water diversion weir, 12- ecological water diversion weir, 13- original retaining dam, 14- original overflow dam, 15- ecological spur dike. DETAILED DESCRIPTION

[0053] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0054] During the dismantling of the dam, due to the lack of consideration of the pre-treatment of sedimentation in the reservoir area and the rapid dismantling of the dam, a large amount of sediment deposited in the reservoir area for many years was quickly discharged into the downstream, and the riverbed for several kilometers or even dozens of kilometers downstream was covered with fine-grained sediment, and the cross section of the river was flattened. On the one hand, the original fish spawning grounds and other natural geomorphic units were buried, the pores between the matrix of the feeding ground disappeared, the habitats required by benthic animals and other organisms for fish prey were degraded, and the large-sized pebbles required for fish spawning and sticky egg attachment were covered; on the other hand, after the deep pools and shoals in the natural rivers were buried, the wide and shallow rivers were greatly affected by the light and the water temperature changed greatly, and the wintering grounds and cold-water fish lurking areas required for the survival of bottom fish disappeared.

[0055] For river sections with damaged habitats due to the withdrawal of small hydropower, this application provides a "flushing out the fine and filling in the coarse" type riverbed sediment habitat restoration method, which aims to restore the riverbed sediment habitat of the original reservoir area and the river section downstream of the dam through facilities such as pebble supplementation, boulder group layout, ecological spur dikes and ecological water diversion weirs, and use natural hydrological forces such as floods to restore the natural landform of the river, form a natural river habitat system with spawning grounds, refuges, wintering grounds, etc., and restore the damaged river sections that have been degraded due to the withdrawal of small hydropower.

[0056] Among them, "scouring" refers to the use of water flow power to flush out unreasonable fine sediment and move it to the downstream or to the part where it can be deposited. Among them, fine sediment refers to sand, silt and clay with a particle size of less than 2mm.

[0057] "Coarse filling" refers to the addition of pebbles that are too fine and lack the sticky eggs of fish to attach to and the juvenile fish to take shelter. The particle size range of pebbles is 16mm to 80mm.

[0058] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0059] In an exemplary embodiment, Figure 1 As shown, a method for riverbed bottom habitat restoration of a river section where small hydropower is withdrawn by "flushing fine and filling coarse" is provided, including the following steps 101 to 105.

[0060] Step 101, obtaining hydrological and geomorphological information of the river channel where small hydropower has been withdrawn.

[0061] The hydrological and geomorphological information includes basic information of the river channel, a riverbed topographic map within the river section affected by the withdrawal of small hydropower, a riverbed matrix particle size distribution map within the river section affected by the withdrawal of small hydropower, and a siltation layer distribution map within the river section affected by the withdrawal of small hydropower.

[0062] In a specific example, a survey of hydrological and geomorphological conditions is conducted on a river channel where small hydropower has been withdrawn, and step 101 includes the following steps 201 to 203.

[0063] Step 201, obtain basic information of the river channel where small hydropower has been withdrawn. The basic information of the river channel includes the length of the river channel, the longitudinal slope of the river channel, the drainage area, the plane shape, the distribution of tributaries, underground rivers, the distribution of bedrock, etc.

[0064] Step 202, determining the position of the river section where the small hydropower station will be withdrawn in the river channel, and determining the impact range of the river section where the small hydropower station will be withdrawn according to the position of the river section where the small hydropower station will be withdrawn in the river channel.

[0065] Specifically, first, according to the position of the river section where the small hydropower station will be withdrawn in the river channel and the water level-capacity curve of the reservoir area, the scope of the reservoir area before the small hydropower station is removed is determined. Then, according to the position of the river section where the small hydropower station will be withdrawn in the river channel, the longitudinal slope of the downstream river channel, the distribution of the stepped riverbed and the gently sloping river channel are determined. According to the longitudinal slope of the downstream river channel, the distribution of the stepped riverbed and the gently sloping river channel, the impact range of the downstream sediment release after the removal of the small hydropower station is determined. Then, according to the reservoir area before the removal of the small hydropower station and the impact range of the downstream sediment release after the removal of the small hydropower station, the impact range of the river section where the small hydropower station is withdrawn is determined. Among them, the impact range of the river section where the small hydropower station is withdrawn includes the reservoir area before the removal of the small hydropower station and the impact range of the downstream sediment release after the removal of the small hydropower station.

[0066] Step 203, within the influence range of the river section where the small hydropower is withdrawn, riverbed topography mapping, riverbed matrix particle size analysis and siltation layer thickness measurement are carried out, and a riverbed topography map within the river section affected by the withdrawal of small hydropower, a riverbed matrix particle size distribution map within the river section affected by the withdrawal of small hydropower and a siltation layer distribution map of the river section affected by the withdrawal of small hydropower are drawn.

[0067] Among them, the thickness of the silt layer is measured by on-site drilling and excavation, the thickness of the silt layer in the affected river section is determined, and a silt layer distribution map is drawn.

[0068] Step 102, based on the basic information of the river channel, the hydrodynamic condition judgment method is used to determine the distribution of key habitat areas in the river section affected by the withdrawal of small hydropower, based on the hydrodynamic sediment transport model and the accessibility requirements of key habitats for aquatic organisms, and draw a key habitat restoration layout map. Among them, the accessibility requirements for key habitats for aquatic organisms refer to conditions such as the distance cannot be too far, or the connecting path must be unobstructed, the water depth must be sufficient and cannot be stranded, etc.

[0069] Specifically, based on the basic information of the river channel, the hydrodynamic condition judgment method is adopted to establish a hydrodynamic sediment transport model, determine the riverbed shields number (shear strength), matrix Reynolds number or Froude number distribution map, and judge the possible terrain after the upstream and downstream water flow scours. Based on the above hydrodynamic conditions, the regional distribution of key habitats such as spawning grounds, feeding grounds, wintering grounds, and cold-water fish lurking areas in the affected river section is judged, and a key habitat restoration layout map is drawn.

[0070] Step 103, based on the key habitat restoration layout map, the riverbed topography map, the riverbed matrix particle size distribution map and the silt layer distribution map, determine the matrix particle size of the key habitat area and the location and thickness of the silt to be flushed by water flow.

[0071] In a specific example, based on the key habitat restoration layout map and the riverbed substrate particle size distribution map, the substrate particle size of the key habitat area is evaluated to obtain the substrate particle size situation of the key habitat area.

[0072] Specifically, the required particle size range and degree of compliance are determined by evaluating the substrate particle size in key habitat areas. For example, the spawning site needs to be based on the suitable pebble particle size range of 16mm to 80mm for spawning of a local protected target fish, and the actual particle size range of the sediment covered by the silt layer is determined to determine the degree of compliance, and what particle size of pebbles are still missing.

[0073] According to the key habitat restoration layout map, the riverbed topography map and the silt layer distribution map, the location and thickness of the key habitat area to be silted by water flow are determined. For example, the water depth required for the cold-water fish lurking area must exceed 1.5m to ensure a stable bottom water temperature in summer, so the thickness of the silt layer to be removed is determined based on the water depth conditions in the area.

[0074] Step 104, determining a riverbed habitat restoration plan based on the key habitat restoration layout diagram, the substrate particle size of the key habitat area, and the location and thickness of the siltation by water flow.

[0075] In one embodiment, the critical habitat areas include spawning grounds, feeding grounds, wintering grounds, and cold-water fish lurking areas.

[0076] The riverbed habitat restoration plan includes a pebble supplement plan, a boulder group layout plan, an ecological spur dike setting plan and an ecological water diversion weir setting plan. This application constructs modular facilities for the reservoir area and the downstream sediment release impact area after the removal of small hydropower stations. The following is a detailed introduction to each modular facility.

[0077] (1) Pebble supplementation program

[0078] The pebble replenishment scheme is to add pebbles to the areas where the particle size of the sediment layer in the convex bank of the river channel is smaller than the set coarse particle size threshold.

[0079] Specifically, the pebble supplementation plan refers to the area where the existing sediment layer is too fine in size and it is necessary to artificially add coarse-grained pebbles from the outside of the river to supplement the existing sediment layer. When supplementing pebbles, the supplementary weight, particle size range and shape requirements need to be designed.

[0080] The weight of the added pebbles is: W s =h c ×S c ×ρ d ×[(1-a) / 0.4-a]; where, W s is the weight of the pebble; h c is the thickness of the sediment layer in the spawning ground, m; S c is the area of ​​the spawning ground, m 2 ρ d is the density of the sediment layer, kg / m 3 ; a is the matrix content in the alluvial soil sample that meets the particle size range of the spawning ground, %.

[0081] The particle size of the supplemented pebbles is larger than the set median particle size. Specifically, when supplementing pebbles, the particle size range should be controlled by screening, and the median particle size is determined according to the formula for the stable anti-scouring particle size of the footing stone under the design peak flow conditions of the river channel (that is, the content of pebbles larger than this particle size should not be less than 50%). For details of the anti-scouring particle size formula, please refer to Appendix D.3.4 of the "Design Code for Embankment Engineering" (GB50286); the particle size required for spawning of target fish is used as the supplementary particle size (upper and lower limits).

[0082] The roundness of the supplemented pebbles is greater than the set roundness threshold. Specifically, the supplemented pebbles cannot be replaced by sharp blocks of stone. The roundness threshold is 0.6. The roundness calculation formula of the pebble is: Among them, Ψp is the roundness of the pebble, S is the length of the minor axis of the pebble, L is the length of the major axis of the pebble, and I is the length of the median axis of the pebble.

[0083] (2) Ecological spur dike setting plan

[0084] The ecological spur dike setting plan is to set up ecological spur dikes in the concave banks of the river, reservoir areas and local flat river sections, and use the water flow power to flush out the sediment with a particle size smaller than the set fine particle size threshold.

[0085] Ecological spur dikes are mainly used to repair flat river sections and sort the riverbed matrix to form diverse landforms with scour holes at the dam head and siltation zones behind the dam. The matrix in the scour holes is coarsened, and fine-grained sediment is concentrated behind the dam by the rolling action of water flow.

[0086] The main concerns in the setting of ecological spur dikes are the depth and diameter of the scouring pit, the length of the siltation zone and the thickness of the siltation. The depth and particle size of the scouring pit should meet the spawning needs of torrent-type sticky-egg fish. If the particle size is insufficient, large-sized pebbles can be artificially supplemented. Because fish need to enter the nearby feeding grounds to forage after spawning, the siltation zone downstream of the scouring pit can be constructed as a feeding ground and a habitat for large invertebrates.

[0087] In a specific example, the length and placement angle of the ecological spur dike are determined according to the bed-forming flow or the design flood flow, and sediment transport simulation is performed based on a hydrodynamic model.

[0088] like Figure 2 As shown, the present application adjusts the cross section of the meandering river covered by fine-grained sediment to form a cross-sectional shape with deep pools and shallows. For the reservoir area, the sediment cover layer 1 is released, and an ecological spur dike is set up on the concave bank of the river to "finely scour" to form a deep pool 2, which can be used as a wintering ground and a low-water-temperature lurking area in summer; and pebbles are added on the convex bank of the river to "coarse" to form a shallow shoal 4, which can be used as a feeding ground and spawning ground.

[0089] (3) Boulder Group Layout Plan

[0090] The plan for arranging the boulder groups is to set up boulder groups in the wide and shallow parts of the straight river channel, the water inlet of the hydropower station and the flood discharge channel, and use the power of water flow to wash away the sediment with a particle size smaller than the set fine particle size threshold.

[0091] Specifically, Figures 3 to 5As shown, the boulder group 5 is set at the water intake 6 of the original hydropower station, the flood discharge channel, the river section with a wide and straight river channel, a gentle longitudinal slope (0.5% to 1% slope) and a large amount of fine-grained silt sediment on the riverbed matrix. The size of a single boulder should at least meet the flood control stability requirements for 50 or 100 years and will not be washed away under the design flood standard flow.

[0092] The present application releases the sediment cover 1 in the reservoir area, sets up a group of boulders 5 in the wide and shallow part of the straight section of the river, "scours and refines" the surroundings of the boulders, sorts the particles and forms scouring pits 7, and the scouring and silting landform formed becomes a good feeding ground.

[0093] This application further sets up boulder groups and ecological spur dikes in the reservoir area and local flat river sections where the deep channel line has deviated due to siltation and the original water intake and drainage structures, so as to form a deep channel line close to the center of the river channel in a "fine-fining" manner, and wash the fine particle cover layer to the shore side, covering the original deep channel line to form a stable bank slope. The riverbed of the newly formed deep channel line of the river is "coarsened", which is conducive to the migration channel of fish with requirements for water depth, and the river bank is refined to become a habitat for large invertebrates and a feeding ground for fish.

[0094] (4) Ecological water diversion weir setting plan

[0095] The plan for setting up ecological water diversion weirs is to set up ecological water diversion weirs in straight river sections and at the entrances of river bends where the slope is less than the set slope threshold, and use the power of water flow to flush sediment with a particle size smaller than the set fine particle size threshold, so that the fine-grained sediment in the riverbed is flushed to both sides of the downstream of the ecological water diversion weir.

[0096] In a specific example, the slope threshold is set at 3%. Ecological water diversion weirs can be used to redirect the deep river line, so that water flows through shallow river sections to restore fish migration channels and flush fine-grained sediment in the center of the river to both sides of the river. Figure 6 As shown, the shape of the ecological water diversion weir is a "V" or "U" shape that opens upstream. The materials of the ecological water diversion weir can be wood, stone, etc., but the foundation should exceed the depth of the scouring pit to prevent instability. There is a layer of bottom rock 8 at the bottom of the ecological water diversion weir. According to actual conditions, a stone 9 with a size larger than the other wave crests is placed at the center of the ecological water diversion weir. The width 10 of the ecological water diversion weir is variable, and the length 11 of the ecological water diversion weir is 1 / 2 to 3 / 4 of the channel width.

[0097] like Figure 7 As shown, in the present application, for the river section where the longitudinal slope of the river section is homogenized and the stepped landform disappears due to the release of the fine-grained sediment cover layer, an ecological water diversion weir 12 is set up to concentrate the water flow to "finely scour" the local area (i.e., to control the water flow and attack the sand) to form a scouring pit, so that the fine-grained sediment in the riverbed is washed to the two sides downstream of the water diversion weir.

[0098] The above schemes are reasonably configured according to the actual river topography and habitat restoration needs, and ultimately achieve systematic restoration of habitats in river sections affected by the withdrawal of small hydropower. The overall layout is as follows: Figure 8 As shown, Figure 8 Among them, 13 represents the original water retaining dam, 14 represents the original overflow dam, and 15 represents the ecological spur dam.

[0099] Step 105, based on the riverbed bottom habitat restoration scheme and the hydrodynamic sediment transport model, simulate the restoration effect of the river channel where small hydropower has been withdrawn, and adjust the riverbed bottom habitat restoration scheme according to the simulation results to obtain the optimal riverbed bottom habitat restoration scheme. The optimal riverbed bottom habitat restoration scheme is used to restore the riverbed bottom habitat of the river channel where small hydropower has been withdrawn.

[0100] In a specific example, a hydrodynamic sediment transport model is used to predict the restoration effects of various schemes for the entire river section, and a riverbed matrix particle size distribution map is formed. The map is compared with the hydrodynamic conditions in step 102 and the evaluation results in step 103 to determine the stability of the riverbed matrix after scouring and silting, determine the specific predicted effect after the implementation of the scheme, and fine-tune the relevant parameters of the scheme to ultimately form the optimal riverbed bottom habitat restoration plan.

[0101] This application can shape suitable hydrodynamic conditions, set up "targeted scouring and silting" for the original reservoir area and the downstream river section of the dam after the removal of small hydropower, sort the riverbed sediment into natural particles, change the distribution of the original riverbed matrix, and form a natural river habitat system with spawning grounds, wintering grounds, and feeding grounds, reduce the problem of damaged river habitats due to the withdrawal of small hydropower, quickly repair river habitats affected by the withdrawal of small hydropower, restore the natural landforms of rivers, increase the diversity of river hydrology, landforms, and matrix conditions, and create habitats required by various fish, including spawning grounds, feeding grounds, foraging grounds, refuges, low-temperature lurking areas, etc., to form systematic geomorphic conditions that are conducive to the life history of fish. Moreover, this application not only considers the survival needs of fish, but also strengthens the habitat conditions suitable for the survival of aquatic organisms such as large benthic invertebrates and aquatic plants, and meets the habitat requirements of species diversity.

[0102] Based on the same inventive concept, the embodiment of the present application also provides a small hydropower withdrawal section "flushing fine and filling coarse" type riverbed bottom habitat restoration system for realizing the above-mentioned small hydropower withdrawal section "flushing fine and filling coarse" type riverbed bottom habitat restoration method. The implementation scheme for solving the problem provided by this system is similar to the implementation scheme recorded in the above-mentioned method, so the specific limitations in one or more embodiments of the small hydropower withdrawal section "flushing fine and filling coarse" type riverbed bottom habitat restoration system provided below can refer to the above-mentioned limitations on the small hydropower withdrawal section "flushing fine and filling coarse" type riverbed bottom habitat restoration method, and will not be repeated here.

[0103] In an exemplary embodiment, Fig. 9 As shown, a riverbed bottom habitat restoration system of the "flushing fine and filling coarse" type for river sections where small hydropower stations have withdrawn is provided, including: an information acquisition module 901, a key habitat determination module 902, a key habitat analysis module 903, a scheme determination module 904 and a scheme adjustment module 905.

[0104] The information acquisition module 901 is used to acquire the hydrological and geomorphic information of the river channel where the small hydropower has been withdrawn. The hydrological and geomorphic information includes basic information of the river channel, riverbed topography in the river section affected by the withdrawal of small hydropower, riverbed matrix particle size distribution map in the river section affected by the withdrawal of small hydropower, and siltation layer distribution map in the river section affected by the withdrawal of small hydropower.

[0105] The key habitat determination module 902 is used to determine the distribution of key habitat areas in the river section affected by the withdrawal of small hydropower, and draw a key habitat restoration layout map based on the basic information of the river channel, the hydrodynamic condition judgment method, the hydrodynamic sediment transport model and the accessibility requirements of key habitats for aquatic organisms.

[0106] The key habitat analysis module 903 is used to determine the substrate particle size of the key habitat area and the location and thickness of the siltation using water flow based on the key habitat restoration layout map, the riverbed topography map, the riverbed substrate particle size distribution map and the siltation layer distribution map.

[0107] The scheme determination module 904 is used to determine the riverbed substrate habitat restoration scheme based on the key habitat restoration layout diagram, the matrix particle size of the key habitat area, and the location and thickness of the water flow scouring and silting; the riverbed substrate habitat restoration scheme includes a pebble supplement scheme, a boulder group layout scheme, an ecological spur dike setting scheme, and an ecological water diversion weir setting scheme.

[0108] The scheme adjustment module 905 is used to simulate the restoration effect of the river channel where small hydropower has been withdrawn based on the riverbed sediment habitat restoration scheme and the hydrodynamic sediment transport model, and adjust the riverbed sediment habitat restoration scheme according to the simulation results to obtain the optimal riverbed sediment habitat restoration scheme.

[0109] In an exemplary embodiment, a computer device is provided, which may be a server or a terminal. The computer device includes a processor, a memory, an input / output interface (I / O) and a communication interface. The processor, the memory and the input / output interface are connected via a system bus, and the communication interface is connected to the system bus via the input / output interface. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the computer device is used to store hydrological and geomorphological information of a river channel where small hydropower has been withdrawn. The input / output interface of the computer device is used to exchange information between the processor and an external device. The communication interface of the computer device is used to communicate with an external terminal via a network connection. When the computer program is executed by the processor, a method for repairing the riverbed substrate habitat of a river section where small hydropower has been withdrawn from the river is implemented by "flushing fine and filling coarse" type.

[0110] In an exemplary embodiment, a computer-readable storage medium is provided, storing a computer program, and when the computer program is executed by a processor, the steps in the above method embodiments are implemented.

[0111] In an exemplary embodiment, a computer program product is provided, including a computer program, and when the computer program is executed by a processor, the steps in the above method embodiments are implemented.

[0112] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of relevant data must comply with relevant regulations.

[0113] Those of ordinary skill in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to the memory, database or other medium used in the embodiments provided in the present application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM may be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM).

[0114] The database involved in each embodiment provided in this application may include at least one of a relational database and a non-relational database. The non-relational database may include a distributed database based on blockchain, etc., but is not limited thereto. The processor involved in each embodiment provided in this application may be a general-purpose processor, a central processing unit, a graphics processor, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, etc., but is not limited thereto.

[0115] The technical features of the above embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0116] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for those skilled in the art, according to the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A method for restoring riverbed habitats in a river section where small hydropower stations have withdrawn from the project by "flushing fine soils and filling coarse soils" is characterized by: The "flushing fine and filling coarse" type riverbed bottom habitat restoration method for the river section where small hydropower is withdrawn includes: Obtaining hydrological and geomorphological information of the river channel where small hydropower has been withdrawn; the hydrological and geomorphological information includes basic information of the river channel, riverbed topography within the river section affected by the withdrawal of small hydropower, riverbed matrix particle size distribution map within the river section affected by the withdrawal of small hydropower, and siltation layer distribution map within the river section affected by the withdrawal of small hydropower; According to the basic information of the river channel, the hydrodynamic condition judgment method is adopted, based on the hydrodynamic sediment transport model and the accessibility requirements of key habitats for aquatic organisms, to determine the distribution of key habitat areas in the river section affected by the withdrawal of small hydropower, and draw a key habitat restoration layout map; Determine the substrate particle size of the key habitat area and the location and thickness of the siltation by water flow according to the key habitat restoration layout map, the riverbed topography map, the riverbed substrate particle size distribution map and the siltation layer distribution map; Determine the riverbed bottom habitat restoration plan based on the key habitat restoration layout map, the substrate particle size of the key habitat area, and the location and thickness of the siltation by water flow; the riverbed bottom habitat restoration plan includes a pebble supplement plan, a boulder group layout plan, an ecological spur dike setting plan, and an ecological water diversion weir setting plan; Based on the riverbed sediment habitat restoration plan and the hydrodynamic sediment transport model, the restoration effect of the river channel where small hydropower has been withdrawn is simulated, and the riverbed sediment habitat restoration plan is adjusted according to the simulation results to obtain the optimal riverbed sediment habitat restoration plan.

2. The method for riverbed habitat restoration of the "flushing fine and filling coarse" type in the river section where small hydropower is withdrawn according to claim 1 is characterized in that: Obtain hydrological and geomorphological information on the river channels where small hydropower has been withdrawn, including: Obtain basic information on rivers where small hydropower has been withdrawn; Determine the location of the river section where the small hydropower station will be withdrawn in the river channel, and determine the impact range of the river section where the small hydropower station will be withdrawn according to the location of the river section where the small hydropower station will be withdrawn in the river channel; Within the influence range of the river section where small hydropower is to be withdrawn, riverbed topography mapping, riverbed matrix particle size analysis and silt layer thickness measurement are carried out, and a riverbed topography map, a riverbed matrix particle size distribution map and a silt layer distribution map of the river section affected by the withdrawal of small hydropower are drawn.

3. The method for riverbed habitat restoration of the "flushing fine and filling coarse" type in the river section where small hydropower is withdrawn according to claim 2 is characterized in that: According to the location of the river section where the small hydropower station is to be withdrawn in the river channel, the impact range of the river section where the small hydropower station is to be withdrawn is determined, including: Determine the scope of the reservoir area before the removal of the small hydropower station according to the location of the river section where the small hydropower station will be removed in the river channel and the water level-reservoir capacity curve of the reservoir area; According to the position of the small hydropower exit river section in the river channel, determine the longitudinal slope of the downstream river channel, the distribution of stepped riverbed and the gentle slope section of the river channel; Determine the impact range of downstream sediment release after the removal of small hydropower stations based on the longitudinal slope of the downstream river channel, the distribution of the stepped riverbed and the gentle slope section of the river channel; The impact scope of the river section where the small hydropower station will be withdrawn is determined based on the reservoir area before the small hydropower station is dismantled and the impact scope of downstream sediment release after the small hydropower station is dismantled.

4. The method for riverbed habitat restoration of the "flushing fine and filling coarse" type in the river section where small hydropower is withdrawn according to claim 1 is characterized in that: According to the key habitat restoration layout map, the riverbed topography map, the riverbed matrix particle size distribution map and the silt layer distribution map, the matrix particle size of the key habitat area and the location and thickness of the siltation by water flow are determined, specifically including: According to the key habitat restoration layout map and the riverbed substrate particle size distribution map, the substrate particle size of the key habitat area is evaluated to obtain the substrate particle size situation of the key habitat area; According to the key habitat restoration layout map, the riverbed topography map and the silt layer distribution map, the location and thickness of the key habitat area to be scoured and silted by water flow are determined.

5. The method for riverbed habitat restoration of the "flushing fine and filling coarse" type in the river section where small hydropower is withdrawn according to claim 1 is characterized in that: The key habitat areas include spawning grounds, feeding grounds, wintering grounds and cold-water fish lurking areas.

6. The method for riverbed habitat restoration of the "flushing fine and filling coarse" type in the river section where small hydropower is withdrawn according to claim 1 is characterized in that: The pebble replenishment scheme is to replenish pebbles in the area where the particle size of the sediment layer in the convex bank of the river channel is smaller than the set coarse particle size threshold; The boulder group layout plan is to set up boulder groups in the wide and shallow parts of the straight river, the water intake of the hydropower station and the flood discharge channel, and use the water flow power to wash away the sediment with a particle size smaller than the set fine particle size threshold; The ecological spur dike setting scheme is to set up ecological spur dikes in the concave banks of the river channel, the reservoir area and the local flat river section, and use the water flow power to flush the sediment with a particle size smaller than the set fine particle size threshold; The ecological water diversion weir setting plan is to set up ecological water diversion weirs in straight river sections and river bend entrances in streams with slopes less than a set slope threshold, and use water flow power to flush sediment with particle sizes less than a set fine particle size threshold, so that the fine-grained sediment in the riverbed is flushed to both sides of the downstream of the ecological water diversion weir.

7. The method for riverbed habitat restoration of the "flushing fine and filling coarse" type in the river section where small hydropower is withdrawn according to claim 6 is characterized in that: The weight of the pebbles added by the pebble supplementation scheme is: W s =h c ×S c ×ρ d ×[(1-a) / 0.4-a]; where, W s is the weight of the pebble, h c is the thickness of the sediment layer in the spawning ground, S c is the area of ​​the spawning ground, ρ d is the density of the sediment layer, a is the matrix content in the sediment layer soil sample that meets the particle size range of the spawning ground; The particle size of the pebbles supplemented by the pebble supplementation scheme is larger than the set median particle size; The roundness of the pebbles supplemented by the pebble supplement scheme is greater than 0.

6.

8. The method for riverbed habitat restoration of the "flushing fine and filling coarse" type in the river section where small hydropower is withdrawn according to claim 6 is characterized in that: The length and placement angle of the ecological spur dam set in the ecological spur dam setting scheme are determined according to the bed-making flow or the design flood flow, and based on the sediment transport simulation of the hydrodynamic model.

9. The method for riverbed habitat restoration of the "flushing fine and filling coarse" type in the river section where small hydropower is withdrawn according to claim 6 is characterized in that: The shape of the ecological water diversion weir provided in the ecological water diversion weir setting scheme is a "V" shape or a "U" shape opening upstream.

10. A riverbed bottom habitat restoration system of the "flushing fine and filling coarse" type in the river section where small hydropower is withdrawn, applied to the "flushing fine and filling coarse" type riverbed bottom habitat restoration method of the river section where small hydropower is withdrawn as described in any one of claims 1 to 9, characterized in that: The "flushing fine and filling coarse" type riverbed bottom habitat restoration system for the river section where small hydropower is withdrawn includes: An information acquisition module is used to acquire hydrological and geomorphological information of a river channel where small hydropower has been withdrawn; the hydrological and geomorphological information includes basic information of the river channel, a riverbed topographic map within the river section affected by the withdrawal of small hydropower, a riverbed matrix particle size distribution map within the river section affected by the withdrawal of small hydropower, and a siltation layer distribution map within the river section affected by the withdrawal of small hydropower; A key habitat determination module is used to determine the distribution of key habitat areas in the river section affected by the withdrawal of small hydropower, and draw a key habitat restoration layout map based on the basic information of the river channel, the hydrodynamic condition judgment method, the hydrodynamic sediment transport model and the accessibility requirements of key habitats for aquatic organisms; A key habitat analysis module is used to determine the substrate particle size of the key habitat area and the location and thickness of the siltation by water flow according to the key habitat restoration layout map, the riverbed topography map, the riverbed substrate particle size distribution map and the siltation layer distribution map; A scheme determination module is used to determine a riverbed bottom habitat restoration scheme based on the key habitat restoration layout diagram, the substrate particle size of the key habitat area, and the location and thickness of the siltation by water flow; the riverbed bottom habitat restoration scheme includes a pebble supplement scheme, a boulder group layout scheme, an ecological spur dike setting scheme, and an ecological water diversion weir setting scheme; The scheme adjustment module is used to simulate the restoration effect of the river channel where small hydropower has been withdrawn based on the riverbed sediment habitat restoration scheme and the hydrodynamic sediment transport model, and adjust the riverbed sediment habitat restoration scheme according to the simulation results to obtain the optimal riverbed sediment habitat restoration scheme.

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