Ecological restoration method for lakeside zone based on integration of micro-topography and vegetation community

Abstract

The present application relates to the water ecological restoration technical field, solved the prior art in the fine design, adaptability and robustness aspect existing technical problem, especially relates to a kind of based on microtopography and vegetation community integration's lakeside zone ecological restoration method, based on many years water level and bank slope elevation data, constructs lakeside zone water depth and duration pattern, and bank slope microtopography is parameterized with step elevation, width and slope, and through adjusting parameter calculation correction water depth and hydrodynamic exposure index;Introduce suitability score function to establish the functional response model for realizing the quantitative matching of microtopography step and vegetation community;In a variety of hydrological scenarios, comprehensive ecological function index is used to construct comprehensive evaluation function and robustness index, and the microtopography and vegetation configuration are jointly optimized.The present application changes lakeside zone restoration design from experience zoning to calculable, comparable integrated scheme, and is suitable for natural gentle slope lake bank and multi-type lakeside zone such as urban hard revetment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of water ecological restoration, and provides a lake shore zone ecological restoration method based on micro-topography and vegetation community integration, in particular to a restoration method for optimizing and shaping the micro-topography of the lake shore zone bank slope under the conditions of comprehensively considering water level fluctuation, water depth distribution, hydrodynamic action and target ecological function, and for coordinating and designing the community configuration of submerged plants, floating leaf plants, emergent plants and shore wetland plants. BACKGROUND

[0002] The lake shore zone is a key transitional zone connecting land and water, and has multiple functions such as reducing non-point source pollution, buffering wave erosion, maintaining aquatic habitats and improving landscape and recreation. In the aspect of engineering application, a number of patents have proposed beneficial explorations around the ecological revetment structure and plant zone construction of the lake shore zone. For example, the Chinese invention with publication number CN106381837B discloses a lake shore zone ecological restoration structure system and restoration method, which proposes to arrange the arbor-shrub-grass zone, emergent plant zone and riprap revetment zone in the direction from the bank slope to the lake center, to build an ecological physical base by using the Reynolds mat and ecological bag and to configure the flood-tolerant pioneer plants, so as to take into account water and soil conservation and landscape restoration and to solve the problem of the coordination of water plants and physical base. Correspondingly, the utility models with publication numbers CN206418454U and CN206396706U disclose a gentle slope beach type lake shore zone ecological restoration structure and a steep slope mountain type lake shore zone ecological restoration structure, respectively, which give the combination form of arbor-shrub-grass-emergent plant zone and wave protection device for different slope conditions.

[0003] At the same time, some patents focus more on the landscape configuration of the plant community of the water shore zone. For example, the Chinese invention with publication number CN107347399B discloses an ecological configuration method for water shore zone plant landscape, which proposes to divide the water shore zone into four water level zones, i.e. deep water zone, shallow water zone, intermittent zone and safety zone, to give the list of optional plants and mixed configuration mode for each zone, and to significantly improve the number of plant species and ornamental value of the water shore zone by flattening the field terrain into a gentle slope into water, applying organic fertilizer, using gradual mixed seeding and sowing combination and other steps. In addition, the Chinese invention with publication number CN107347410B discloses a multi-habitat three-dimensional vegetation construction method for dike type lake shore zone, which proposes to divide the dike type lake shore zone into multiple habitat types, and to give the habitat construction mode and vertical three-dimensional vegetation configuration idea for different types of water-land ecotone, which has a positive significance for improving the vegetation diversity and spatial structure of the lake shore zone.

[0004] In summary, the existing lakeside ecological restoration technology can be roughly divided into two categories: one focuses on the construction of "structure + plant" ecological revetment system, which improves water and soil conservation and landscape effect through the combination of physical foundation and plant belt, but the design of micro-topography is still mainly based on experience type slope or simple steps, and there is a lack of quantitative method for fine coupling with hydrological and hydrodynamic conditions; the other focuses on the plant landscape configuration of "zoning + community", although it considers water level zoning and mixed planting of multiple species, but only puts forward the principle requirement for topographic shaping, without giving the steps for determining and optimizing the geometric parameters of micro-topography which can guide engineering design, and lacks quantitative description of the response of vegetation community to environmental factors such as water depth, hydrodynamic force and light, and more does not systematically consider the stability of the scheme under different hydrological scenarios such as dry year, normal year and wet year. The existing technology generally lacks an integrated restoration design method that quantitatively evaluates and multi-scenario, multi-objective optimizes the annual water level and water depth distribution, lakeside micro-topography parameters, hydrodynamic exposure, vegetation functional group environmental response, and engineering stability and cost constraints in a unified framework, making it difficult to provide a calculable, deducible and comparable micro-topography and vegetation community collaborative design tool for different types of lakeside. SUMMARY

[0005] In view of the deficiencies of the prior art, the present application provides a lakeside ecological restoration method based on the integration of micro-topography and vegetation community, which solves the technical problems of the prior art in the aspects of fine design, adaptability and robustness. The deficiencies of the prior art are reflected in the following aspects, that is:

[0006] Lack of quantitative design basis for micro-topographic shaping: existing projects mostly use experience to judge the slope of the bank to be treated as a gentle slope or a step, without systematically converting key hydrological-dynamic information such as multi-year water level process, water depth distribution and hydrodynamic exposure into calculable design parameters of micro-topography elevation, width, slope and relief form, resulting in insufficient matching of micro-topography with actual water level fluctuation and hydrodynamic conditions.

[0007] Disconnection between vegetation community configuration and environmental response: the existing vegetation belt of lakeside is mostly configured according to the experience-based zoning of "deep water area-shallow water area-intermittent area" and the species list, and lacks quantitative response models based on environmental factors such as water depth, hydrodynamic force and light, making it difficult to ensure the suitable habitat and community stability of submerged plants, floating leaf plants, emergent plants and wetland herbs under multi-year fluctuating water level.

[0008] Lack of integrated optimization of micro-topography-vegetation community-engineering stability: the existing technology fails to jointly include ecological functions (such as underwater vegetation continuity and transparency improvement), bank slope engineering stability (soil erosion resistance and sliding resistance), and engineering earthwork volume and cost management constraints into the quantitative evaluation and multi-scenario optimization process in a unified framework, resulting in that the restoration scheme is difficult to balance ecological benefits and engineering implementability under different hydrological scenarios such as dry year, normal year and wet year.

[0009] To solve the above technical problems, the present application fully utilizes multi-year hydrological data and current topographic data, and realizes quantitative collaborative design of micro-topography shaping and vegetation community configuration in lake shore zone through micro-topography parameterization, water depth-water dynamic exposure analysis, vegetation functional group response modeling and multi-scenario comprehensive evaluation, so as to overcome the deficiencies of the prior art in fine design, adaptability and robustness. The lake shore zone restoration design is changed from experience zoning to calculable and comparable integrated scheme, which is suitable for natural gentle slope lake shore and urban hard revetment and other types of lake shore zone. The technical scheme of the present application is as follows:

[0010] To overcome the deficiencies of the prior art in lake shore zone restoration technology, such as micro-topography shaping relying on experience, vegetation configuration being disconnected with environmental response, and lack of ecological-engineering integrated optimization, the present application proposes a lake shore zone ecological restoration method based on micro-topography and vegetation community integration. As shown in the figure, the method generally includes the following steps: basic data acquisition, water depth-water dynamic exposure analysis, vegetation functional group environmental response modeling, micro-topography parameterization and correction calculation, multi-scenario comprehensive evaluation and optimization, and integrated restoration design scheme output. The technical scheme of each link is further described below. Figure 1

[0011] The present application first acquires multi-year water level sequence of the target lake or river-lake water body and current topographic data and bottom material parameters of the lake shore zone under a unified elevation reference. The multi-year water level sequence is preferably continuous daily or hourly water level observation value for not less than 5 years, further not less than 10 years , which can reflect the water level fluctuation characteristics of typical dry years, normal years and wet years. The topographic data is preferably obtained by means of measurement section, RTK measurement or unmanned aerial vehicle laser radar, and is discretized into regular grid or section point in geographic information system, and the grid center elevation is recorded as . The bottom material parameters include soil type, natural unit weight, cohesion, internal friction angle, etc., which are used for subsequent bank slope stability analysis.

[0012] On the basis of the above, the present application divides the target water body into several shore sections along the shoreline direction of the lake shore zone, and divides a plurality of design units in each shore section along the vertical shoreline direction at equal or variable intervals according to elevation, and each design unit is characterized by representative elevation , slope and horizontal width.

[0013] Then the instantaneous water depth of the design unit at time is calculated by the following formula , that is:

[0014]

[0015] When the instantaneous water depth ​When the instantaneous water depth is considered as being above the water surface.

[0016] Preferably, the water depth is divided into several intervals (for example , , , and the like), the frequency of occurrence of each interval on a multi-year scale is counted, and a water depth frequency distribution of the design unit is constructed .

[0017] Further, the present application identifies the continuous flooding time period and the continuous exposure time period by sequentially scanning the water depth time series , forms a flooding duration distribution and an exposure duration distribution .

[0018] Further, these two distributions can be used to limit the upper limit of the flooding tolerance of submerged plants, and to evaluate the adaptability of emergent plants and hydrophytes to dry-wet alternation, thereby expanding the traditional single water level zone into a description of the flooding-exposure rhythm in the time dimension.

[0019] To simultaneously depict the hydrodynamic environment, the present application introduces a hydrodynamic exposure index . Preferably, the following formula or its equivalent form can be used, that is:

[0020]

[0021] wherein, is the representative effective wave height of the design unit under the action of the multi-year wind field and open conditions, is the multi-year average water depth of the design unit , and is the representative bank slope of the design unit . The effective wave height can be estimated according to the wind direction frequency, fetch length and water depth using a simplified wave calculation formula; the larger the value of the hydrodynamic exposure index , the stronger the wave energy and flow velocity shear, and the more significant the bank and vegetation erosion.

[0022] Preferably, in the scenario that needs to be finely depicted, the hydrodynamic exposure index can also be split by season or flood season / non-flood season to reflect the differences in seasonal disturbances.

[0023] To achieve fine matching of vegetation community configuration with actual environmental conditions, the present application introduces candidate vegetation functional group - environment response modeling. The candidate vegetation functional group at least includes one or more of submerged plant functional group, floating leaf plant functional group, emergent plant functional group and riparian wetland herb functional group, each candidate vegetation functional group may contain one or more representative species.

[0024] Preferably, through lakeside belt quadrat investigation and water control, flow control test, the survival rate, coverage or aboveground biomass of each candidate vegetation functional group is determined under a series of water depths and hydrodynamic exposure indexes , and these observed values are normalized to suitability scores , the value range is preferably .

[0025] Preferably, the environmental response curve of each candidate vegetation functional group is fitted by using logistic regression or generalized linear model, and the present application particularly gives the suitability score function in the following form, i.e.:

[0026]

[0027] wherein, is the suitability score of the th candidate vegetation functional group under water depth and hydrodynamic exposure index , is the parameter fitted based on measured data. As shown in Figure 3 and Figure 4 , the suitability curves of different candidate vegetation functional groups in the direction of water depth present different peak positions and widths, the suitability score R of submerged plants is the highest in the medium water depth interval, the peak of emergent plants is reached in the shallow water area, and the wetland herbs have a higher suitability in the interval close to the normal water level.

[0028] Preferably, when the suitability score is greater than a certain threshold (for example, 0.6 or 0.7), the corresponding water depth - hydrodynamic combination is considered as the preferred habitat interval of the functional group, which is suitable for key planting; when the suitability score is lower than a lower threshold (for example, 0.3), it can be considered as an unsuitable area, which is generally not selected in community configuration.

[0029] Further, to more truly reflect the light requirement of submerged plants, the present application introduces vertical light attenuation constraint. The light intensity at water depth is estimated by using the following relationship, i.e.:

[0030] ​

[0031] in, The intensity of light on the water surface. The total optical attenuation coefficient is... The water is deep.

[0032] Preferably, the target planting water depth for submerged plants is specified. Light intensity at the location Not lower than the light compensation point of the candidate vegetation functional group ,Right now:

[0033]

[0034] For water depth-topography combinations that do not meet the above conditions This invention calculates the suitability score. A penalty factor is introduced to force the suitability score to be lowered or recorded as 0, thereby avoiding false suitability zones where the water depth is suitable but the lighting is insufficient.

[0035] By modeling the environmental response under the combined effects of water depth, hydrodynamics, and illumination, this invention can quantitatively identify the optimal growth zone and acceptable habitat range for each functional group in the lakeside space, providing precise ecological constraints for subsequent micro-topography design and community combination.

[0036] To transform micro-topography from conceptual gentle slopes / steps into optimizable design variables, this invention explicitly parameterizes the micro-topography of the lakeshore zone. Preferably, the first... The micro-topography of each design unit is represented by a design parameter vector, i.e., a micro-topography parameter vector. for:

[0037]

[0038] in, For the first Target elevation of stepped or gentle slope sections. For the corresponding horizontal width, To correspond to the slope, The micro-topography level within the unit is usually taken as 3 to 5 levels according to the water level variation and design requirements.

[0039] Preferably, the elevation of some target areas can also be adjusted based on existing roads, embankment crest elevations, and land use boundaries. Introduce engineering constraints that are either "fixed and immutable" or "limited and adjustable." For example... Figure 2 As shown, in a typical cross-section, the first The micro-topography of the first design unit is obtained through the first Target elevation of stepped or gentle slope sections Horizontal width and slope and other parameters, the micro-topographic parameter vector constituting the micro-topography .

[0040] Preferably, after the given micro-topographic parameter vector , the present application recalculates the typical water level under the condition of the revised water depth , i.e.:

[0041]

[0042] and further updates the water depth frequency distribution and the flood duration distribution of each step, and based on the updated average water depth and local slope, revises the hydrodynamic exposure index , to obtain the revised hydrodynamic exposure index . Through this process, the impact of micro-topographic adjustments such as "elevation of steps or lowering of steps, slowing down or steepening of slopes" on the water depth-hydrodynamic environment can be quantitatively evaluated, achieving the coupling between terrain-hydrology-dynamics.

[0043] After the determination of the terrain-hydrology-dynamics conditions, the present application regards each step as a potential vegetation zone, and on each step, according to the revised water depth and the revised hydrodynamic index , the suitability score of different vegetation functional groups is calculated by substituting them into the suitability score function of the vegetation functional groups , and then a step-functional group-suitability matrix is formed.

[0044] Preferably, 2-3 vegetation functional groups with higher suitability scores and stronger functional complementarity on the step can be selected for community combination design, thereby forming a submerged-floating leaf-emersed-wetland gradual structure in the vertical direction and a repeatable micro-topography-community module in the alongshore direction.

[0045] In terms of engineering safety, based on the step slope, soil shear strength and hydrodynamic exposure index, the present application calculates the bank slope safety factor using the conventional slope stability analysis method, which can be generally expressed as:

[0046]

[0047] wherein, is the anti-sliding force or anti-sliding moment, is the sliding force or sliding moment.

[0048] Further, the bank slope safety factor is defined as the bank slope safety threshold​ Select 1.3 or 1.5), and requires the slope to meet this condition in the wet year and under the big wave scenario.

[0049] In addition, the present application calculates the unit coastline earthwork volume by comparing the original terrain and the target micro-terrain elevation, combined with the soil density , which provides the basis for subsequent economic evaluation and construction organization.

[0050] On the basis of the coupling between the above-mentioned terrain-hydrology-dynamics, the present application constructs a comprehensive evaluation system considering ecological function, engineering stability and engineering quantity at the same time, and introduces a robustness index under multiple hydrological scenarios, realizing the integrated optimization of micro-terrain parameters and vegetation community configuration.

[0051] Further, the present application preferably selects the dry year scenario , the normal water year scenario and the wet year scenario , constructs a representative water level process for each scenario , and recalculates the water depth-water dynamics conditions and vegetation suitability of each design scheme under the scenario according to the aforementioned method. For any candidate scheme (including a set of micro-terrain parameter vectors and the corresponding candidate vegetation functional group configuration), the present application calculates the comprehensive evaluation function under the scenario , that is:

[0052]

[0053] Among them, is the underwater vegetation continuity index under the scenario , is the functional diversity index, is the transparency improvement potential index, is the slope safety factor, is the earthwork volume index, is the weight coefficient, which satisfies:

[0054]

[0055] Preferably, for the slope safety factor and the earthwork volume index , it is necessary to do 0-1 normalization before participating in the calculation of the comprehensive evaluation function , so the comprehensive evaluation function is uniformly written as the weighted combination of the normalized index, that is:

[0056]

[0057] Among them, ;​ is the normalized value of the safety factor of the bank slope (e.g. or interval normalization); is the normalized value of the earthwork index.

[0058] Further, the effective length of each design unit in the direction of the coastline is summed up to obtain the effective length of the continuous underwater vegetation zone , i.e.

[0059]

[0060] wherein, the set of design units; is the availability criterion of the design unit under the scenario , i.e.

[0061]

[0062] wherein, is the occurrence ratio of the condition in the growing season or throughout the year (flood frequency / water depth frequency); is the minimum frequency threshold (e.g. 0.5 or 0.6); is the average suitability of the unit under the scenario (or the average in the growing season); is the suitability threshold (e.g. 0.7, corresponding to the optimal suitability zone); is the availability criterion of the design unit at the time of the instantaneous water depth . denotes the target water depth zone of the submerged plants, such as 0.3-0.8m;

[0063] The underwater vegetation continuity index is defined as:

[0064]

[0065] wherein, is the length of the coastline (or the length of the bank section). Obviously is a dimensionless quantity.

[0066] The area of the design unit is .

[0067] Further, the present application obtains the predicted allocation area (or the area along the bank) of each vegetation functional group under the scenario from the suitability criterion or the suitability weighted area , i.e.

[0068] Threshold method:

[0069]

[0070] Weighted method (more smooth):

[0071]

[0072] Let Then:

[0073]

[0074] where, is the set of vegetation functional groups. is a dimensionless quantity.

[0075] In the present invention, the transparency improvement potential indicator is a normalized comprehensive indicator of transparency improvement potential, which is used to reflect the comprehensive contribution of submerged plant coverage, emergent plant wave cutting and sediment disturbance suppression to the improvement of water transparency. This indicator does not require direct prediction of absolute Secchi depth value, but is used for relative evaluation and optimization between candidate schemes (which is the multi-index decision-making idea commonly used in engineering design).

[0076] The spatial average value of the hydrodynamic exposure index under the scenario is calculated as i.e.

[0077]

[0078] where, is the hydrodynamic exposure index of the design unit under the scenario .

[0079] The spatial average value is normalized to 0-1, i.e.

[0080]

[0081] where, is the normalized spatial average value; represents the minimum / maximum value under the set of acceptable candidate schemes (or design variable boundaries), which can be updated with iterations during implementation.

[0082] At the same time, the coverage rate itself is a dimensionless quantity of 0-1, i.e.

[0083]

[0084] where, denotes the predicted coverage ratio or area proportion of submerged plants; denotes the predicted coverage ratio or area proportion of emergent plants.

[0085] The transparency improvement potential indicator is then defined as:

[0086]

[0087] wherein, .

[0088] This definition ensures that is a dimensionless quantity, and is consistent with the mechanism of transparency improvement, i.e. the higher the submerged coverage, the more complete the emergent belt, and the lower the average disturbance, the greater the transparency improvement potential. Those skilled in the art can directly calculate accordingly.

[0089] Preferably, the present application assigns a higher weight to the ecological and stability indicators, and incorporates the earthwork indicator in the form of a negative sign, to reflect the principle of minimizing the amount of engineering while meeting the ecological and safety prerequisites.

[0090] On this basis, the present application defines a scenario robustness indicator A preferred form is:

[0091]

[0092] That is, the minimum value of the comprehensive evaluation function under three scenarios is taken to ensure that the scheme still has an acceptable comprehensive performance under the most unfavorable scenario.

[0093] Another form is a weighted average, i.e.

[0094]

[0095] wherein, is the weight of each scenario, satisfying The present application can flexibly set the weight of each scenario according to the degree of attention of the management department to different hydrological years .

[0096] Further, under the premise of meeting the constraint conditions, the present application maximizes the scenario robustness indicator as the goal, and jointly optimizes the candidate microtopography and vegetation community combination The expression of the constraint condition is:

[0097]

[0098] Preferably, simulated annealing, genetic algorithm or other heuristic optimization methods are used, and the current topography and current community are taken as the initial scheme. The microtopography parameter vector The limited amplitude perturbation, step-by-step screening and acceptance-rejection discrimination are performed on the vegetation functional group combination, the candidate scheme is iteratively updated, and when the improvement amplitude of the scene robustness index in several iterations is lower than a preset threshold value, convergence is considered, and a lakeside belt ecological restoration scheme with strong cross-year scene adaptability is obtained.

[0099] Further, the iterative search or heuristic combinatorial optimization method comprises:

[0100] The current terrain is taken as an initial scheme, and the micro-terrain parameter vector and the vegetation functional group combination are subjected to limited amplitude perturbation.

[0101] The comprehensive evaluation function and the scene robustness index of the scheme after perturbation under each hydrological scene are calculated.

[0102] When the scene robustness index of the perturbed scheme is improved and the constraint condition is met, the scheme is accepted, otherwise it is rejected or accepted with a lower probability, which is used to jump out of the local optimum.

[0103] The iteration is repeated until the improvement amplitude of the scene robustness index in several consecutive iterations is lower than a preset threshold value, and the converged integrated restoration design scheme is output.

[0104] After optimization, the present application converts the calculation results into design results that can be directly applied in engineering, including but not limited to: target elevation, slope, step width and other micro-terrain parameters of each bank section and design unit; functional group combination and planting density of submerged plants, floating leaf plants, emergent plants and wetland herbs in different water depth zones; and standardized micro-terrain-ecosystem combination modules that can be repeatedly laid out on plane and longitudinal and transverse sections.

[0105] Preferably, according to the optimization results, the present application divides the shoreline into several implementation sub-zones, and 1-2 sets of typical micro-terrain-ecosystem combination modules are selected for repeated laying in each sub-zone, which ensures the continuity of overall ecological function, and takes into account construction standardization and local adaptability.

[0106] Further, based on the lakeside belt ecological restoration scheme, the present application outputs the micro-terrain longitudinal and transverse section layout of each bank section of the lakeside belt, the target elevation and slope parameters of each design unit, the vegetation community combination and the planting density, and divides the implementation sub-zones according to the bank sections and water depth gradients, which are used to guide the shaping and vegetation restoration construction of the lakeside belt project.

[0107] Further, the present application further comprises repeatedly laying several micro-terrain-vegetation combination modules along the shoreline direction of the lakeside belt with design units as the scale, and each micro-terrain-vegetation combination module at least comprises:

[0108] A gentle slope deep water platform located in the perennial deep water level interval for planting submerged plants;

[0109] ​The middle water step for planting floating leaf plants and emergent plants in the seasonal flooding area;

[0110] The shallow water step or shore gentle slope for planting wetland herbs and shrubs in the intermittent flooding or shore edge flooding area;

[0111] The steps and gentle slopes at all levels are connected through continuous slopes, and the elevation and width are set according to the lake shore ecological restoration scheme of various hydrological scenarios, so that the continuity of the underwater vegetation zone and the overall stability of the shore slope structure can be maintained in dry, normal and wet scenarios.

[0112] Further, the calculation and visualization process of the present application can be realized through a geographic information system platform or a special design software, but the core of the present application is to propose a design framework of "multi-year water level-water depth distribution-microtopography parameter-water dynamic exposure-vegetation functional group response-shore slope stability-engineering quantity" integrated coupling, which upgrades the microtopography shaping and vegetation community configuration of the lake shore from an empirical method to a quantifiable and optimized engineering design technical scheme.

[0113] Through the above technical scheme, the present application provides a lake shore ecological restoration method based on the integration of microtopography and vegetation community, which has at least the following beneficial effects:

[0114] 1、The present application explicitly converts the multi-year water level process, water depth distribution and water dynamic exposure into a microtopography parameter vector, and through parameterized modeling and calculation correction of elevation, width, slope and number, the water depth-water dynamic conditions corresponding to each step can be quantitatively derived, avoiding the experience-based selection of existing gentle slope and step.

[0115] 2、The present application constructs the response function of the candidate vegetation functional group to the suitability of water depth, water dynamic and light, and matches the water depth , water dynamic exposure index condition after microtopography adjustment step by step, realizes the quantitative selection and spatial combination of submerged, floating leaf, emergent and wetland vegetation zone, and makes the community configuration process calculable, comparable and optimizable, thereby improving the environmental adaptability and long-term stability of the restored community.

[0116] 3、The present application introduces underwater vegetation continuity, functional diversity, transparency improvement potential, shore slope stability safety factor and earthwork quantity in the unified model, constructs comprehensive evaluation function and robustness index under multiple hydrological scenarios, and carries out joint optimization of microtopography and vegetation configuration with the above indexes as the target, realizes the overall trade-off of ecological function and engineering safety, engineering quantity in different scenarios such as dry year, normal year and wet year, which is not possessed by the existing lake shore restoration technology. BRIEF DESCRIPTION OF DRAWINGS

[0117] The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and together with the description serve to explain the application. In the drawings:

[0118] Figure 1 Flow chart of the ecological restoration method of lakeside zone in the present application;

[0119] Figure 2 Design unit schematic diagram of microtopography parameterization expression in the present application, showing the corresponding relationship between parameters such as step elevation, step width and slope and microtopography parameter vector;

[0120] Figure 3 Suitability-water depth response curve diagram of submerged, emergent and hygrophilous functional groups in the present application;

[0121] Figure 4 Illumination attenuation constraint schematic diagram of submerged, emergent and hygrophilous functional groups in the present application;

[0122] Figure 5 Comparison schematic diagram of the present cross section and the microtopography-vegetation zone configuration cross section after design of a typical shallow lake gentle slope shore section in Example 1 of the present application;

[0123] Figure 6 Comparison schematic diagram of the comprehensive evaluation value and the scene robustness index of the pre-optimization scheme and the post-optimization scheme under multiple scenarios of dry year, normal year and wet year in Example 2 of the present application;

[0124] Figure 7 Typical cross section schematic diagram of the additional ecological step structure and vegetation community configuration of the urban hard revetment shore section in Example 3 of the present application. DETAILED DESCRIPTION

[0125] In order to make the above objectives, features and advantages of the present application more apparent, comprehensible and easy to understand, the present application will be further described in detail below with reference to the drawings and specific embodiments. The realization process of how to apply technical means to solve technical problems and achieve technical effects of the present application can be fully understood and implemented.

[0126] Example 1: Microtopography and vegetation community integrated restoration design of a typical shallow lake gentle slope shore section.

[0127] This example takes a natural gentle slope shore section of about 200m long on the east bank of a typical shallow lake as the object, as shown in Figure 5The image shows a typical cross-section of the current state and the designed section of the shoreline. Behind this section are low-lying farmland and rural roads, while the front edge is an open lake. The current shoreline slope is relatively gentle, but it has been eroded by wind and waves over a long period of time, forming a single slope. The underwater vegetation zone is fragmented, and the emergent vegetation zone has receded, with only scattered patches of reeds and cattails remaining in some areas.

[0128] First, water level monitoring data for the lake over the past 10 years was obtained, and a representative "normal water year" was selected as the design hydrological scenario. Using the local elevation datum as 0, the monthly average water level elevation for this representative year was calculated. The water levels for January to December are as follows: 8.90m, 8.92m, 8.95m, 9.00m, 9.05m, 9.10m, 9.15m, 9.12m, 9.05m, 9.00m, 8.95m, and 8.90m, respectively. It can be seen that the lake level fluctuates by approximately 0.25m throughout the year, with a relatively high water level from April to October, and lower water levels from January to March and November to December, consistent with the seasonal water level characteristics of a shallow lake in a typical eastern monsoon climate.

[0129] Regarding the cross-sectional topography, longitudinal and transverse cross-sectional measurements were conducted in the middle of this bank section, resulting in a typical cross-sectional elevation distribution: starting from the inner shoulder of the road on the bank crest, the horizontal distance from the bank crest... Current elevations at positions 0m, 5m, 15m, 25m, and 35m. The elevations are 9.60m, 9.20m, 8.90m, 8.60m, and 8.30m, respectively. It can be seen that the shoreline slopes gently towards the water from the land side, with the elevation gradually decreasing from 8.90m to 8.30m within the 15–35m range, corresponding to an average slope of approximately 0.6 / 20 ≈ 1:33. The lakeshore substrate is mainly composed of silty clay with a natural unit weight of approximately 18 kN / m³. 3 With a cohesion of approximately 12 kPa and an internal friction angle of approximately 18°, it meets the stability requirements of conventional gentle slope revetments.

[0130] Under current conditions, the 15–35m range is defined as the main lakeshore zone. Based on the aforementioned water level data, the time series of water depth at different representative elevations are calculated. Taking elevation 8.60m as an example, representing the deep-water nearshore zone, its average water depth for each month is... The water depth is approximately 0.30m, 0.32m, 0.35m, 0.40m, 0.45m, 0.50m, 0.55m, 0.52m, 0.45m, 0.40m, 0.35m, and 0.30m respectively from January to December. The area is flooded year-round, with an average water depth of approximately:

[0131]

[0132] Approximately 0.41 m. Taking the elevation of 8.90 m as an example (the current middle gentle slope position), the average water depth from January to December is 0, 0.02, 0.05, 0.10, 0.15, 0.20, 0.25, 0.22, 0.15, 0.10, 0.05, 0 m, where the flood state is from February to November, the flood frequency is about 10 / 12 = 83%, and the average water depth is about:

[0133]

[0134] About 0.11 m. Taking the elevation of 9.05 m as an example (near the shallow edge of the normal water level), only in June-August, the water level is slightly higher than this elevation, corresponding to water depth of about 0.05 m, 0.10 m, 0.07 m, and the rest of the month is exposed, the annual average water depth is about:

[0135]

[0136] The flood frequency is about 3 / 12 = 25%. The above calculation results show that the lower part of the current bank slope is always flooded, suitable for submerged plants but the slope is steep and disturbed by waves; the middle part is mostly shallow water, has certain potential for emergent plants but lacks stable steps; the upper part is only flooded for a short time during the wet season, which is not conducive to the formation of continuous wetland plant zones, resulting in discontinuous distribution of the overall vegetation zone.

[0137] In terms of vegetation functional groups, the embodiment selects three typical functional groups: submerged plant functional group (denoted as , represented by the Elodea- Vallisneria community), emergent plant functional group , represented by Typha, Phragmites), and riparian wetland herb functional group , represented by the Cyperus, Gramineae wetland weed community). According to the existing survey data and indoor water control test results of the lake area, the suitable range and optimal interval of each functional group to water depth and water dynamic exposure index are given. For the submerged plant functional group , it has a higher dominance under the condition of water depth 0.3-1.2 m and moderate or below waves, and the coverage decreases significantly when the water depth is below 0.2 m or above 1.5 m; the emergent plant functional group performs well in the range of 0-0.5 m water depth, especially between 0.1-0.3 m, which is beneficial to the stability of the root system and the emergence of the aboveground part to form a dense vegetation zone; the wetland herb functional group is preferably arranged within 0.2 m above and below the normal water level, requiring high soil moisture content but not long-term deep water submersion. The suitable degree response function obtained by fitting the measured data is:

[0138]

[0139] When the suitability score is considered to be an optimal suitability zone, is considered to be a suitable zone, is considered to be an unsuitable zone.

[0140] In this embodiment, since the bank section is a relatively leeward bank, the representative significant wave height is about 0.20-0.30m, and the hydrodynamic exposure index is generally low. The hydrodynamic factor mainly manifests in inhibiting the colonization of submerged plants in the outermost deep water area, and the specific parameters are not expanded in this embodiment.

[0141] After grasping the above hydrological-terrain and vegetation response relationship, this embodiment carries out micro-terrain-vegetation integrated design on the gentle slope bank section according to the method of the present application, aiming to construct a continuous submerged plant belt, a stable emergent plant belt and a wetland herb belt with a certain width within the 200m shoreline range. In combination with the present situation terrain and construction feasibility, this embodiment designs a three-belt integrated micro-terrain step along the representative section, i.e., the submerged plant step is selected at an elevation of 8.60m and is arranged in a width of 10m along the shore direction; the emergent plant step is selected at an elevation of 8.90m and is arranged in a width of 7m; and the wetland herb step is selected at an elevation of 9.05m and is arranged in a width of 5m, which is naturally transitioned to the land side to the bank top elevation of 9.60m without substantial modification. The short slopes with a slope ratio of about 1:3 are connected between the steps to form the micro-terrain combination of wide and gentle steps + short and steep slopes transition under the background of the overall gentle slope with a slope ratio of about 1:33.

[0142] According to the step elevations and water level sequence, the flooding conditions of each step in the representative year are calculated. For the submerged plant step (8.60m), it is in the flooding state all year round, with an average water depth of about 0.41m, a minimum monthly average water depth of about 0.30m and a maximum of about 0.55m, completely falling into the optimal suitability zone, and the flooding frequency is 100%, which can form a stable submerged plant continuous belt. For the emergent plant step (8.90m), it is in the shallow flooding state from February to November, corresponding to a water depth of between 0.02-0.25m, and the water depth is basically in the range of 0.10-0.22m from April to September, which meets the optimal range, and the short-term exposure in January and December is beneficial to root aeration and renewal, with an annual flooding frequency of about 83%, which can stably form an emergent vegetation belt of cattail and reed. For the wetland herb step (9.05m), only 0.05-0.10m shallow flooding occurs during the high water period from June to August, and it is exposed at other times, the soil maintains a high water content but does not accumulate water for a long time, which is very suitable for community colonization.

[0143] ​​From the spatial structure, the designed cross section provides a basic constant water depth zone of about 10 m in the water depth interval of 0.3-0.8 m, which is obviously increased compared with the existing suitable water depth zone width of less than 5-6 m; in the water depth interval of 0-0.3 m, the emergent plant step provides a special zone width of about 7 m, avoiding the problems of local soil being too steep, root system being exposed and being easily washed away in the existing state; in the interval of ±0.2 m near the normal water level, the wet grass step provides a width of about 5 m, which is used to build a dense riparian herb zone, improve the landscape of the shoreline and prevent local collapse caused by pedestrians stepping on. According to the underwater vegetation continuity index of the present application , the underwater vegetation continuity index of the existing cross section is about 0.3-0.4, which can be increased to about 0.8 after the design, indicating that the continuity and integrity of the underwater vegetation zone are significantly improved.

[0144] In terms of earthwork and stability, the embodiment balances the cut and fill of the earthwork in the interval of 15-35 m on the cross section, appropriately adjusts the step width and slope foot position, and makes the submerged step mainly cut, and the emergent and wet steps fill a small amount of earthwork. Finally, the net earthwork amount of the cross section is controlled within about 0.10-0.15 m 3 / m of the shoreline, the overall slope stability safety factor calculated by the simplified strip method is not less than 1.5, meeting the safety requirements of the lake embankment. Considering the 200 m shoreline range, the total earthwork amount of the scheme is about 20-30 m 3 , which is significantly lower than the earthwork demand of the traditional large-scale slope or high-standard ecological retaining wall scheme.

[0145] In terms of vegetation configuration, the embodiment arranges submerged plants such as Elodea and Vallisneria on the submerged step, the planting zone width is 8-10 m, and the planting density is 6-8 plants / m 2 ; the cattail and reed are planted on the emergent step, and part of the Acorus calamus is appropriately mixed inside and outside to improve the landscape diversity, and the average planting density is 3-4 plants / m 2 ; the wet grass species such as Imperata cylindra and Eragrostis curvula are sown on the wet grass step, and a small amount of Acorus calamus and Iris pseudacorus are also planted to form a herb zone mainly composed of native species. According to the estimation results of the suitability function , the three vegetation zones after the design are in the optimal zone or the suitable zone of their respective functional groups for most of the time in the representative year, and it is expected that a relatively stable three-level shoreline community structure of "submerged-emergent-wet" can be formed within 2-3 growth seasons.

[0146] In summary, the embodiment fully demonstrates the whole process of the method of the application from the multi-year water level and cross-section topographic data, through water depth-flood duration analysis, vegetation functional group environmental response determination, micro-topographic step parameterization design and correction calculation, to finally form a lake shore zone micro-topography and community integrated restoration scheme with clear elevation, width and vegetation configuration, proving the feasibility and effectiveness of the technical scheme of the application in actual engineering scenarios.

[0147] Example 2: Optimization design of micro-topography and vegetation community integrated restoration scheme under multiple hydrological scenarios.

[0148] On the basis of the same 200m gentle slope shore section on the east shore of the shallow lake in the embodiment, three representative hydrological scenarios of dry year, normal year and wet year are introduced, and the micro-topographic step parameters and vegetation community configuration are comprehensively evaluated and robustly optimized under multiple scenarios, further embodying the adaptive design capability of the method of the application under the condition of “the same shore section in different years”. Without changing the basic data and construction conditions in Example 1, the embodiment focuses on the calculation process of the multi-scenario comprehensive evaluation function and the scenario robustness index, and the quantitative comparison of the comprehensive performance of the schemes before and after optimization under each scenario.

[0149] In terms of hydrological scenario construction, the monthly average water level sequence of “normal year” selected in Example 1 is still taken as the benchmark, i.e. the average water level elevations of January-December are 8.90m, 8.92m, 8.95m, 9.00m, 9.05m, 9.10m, 9.15m, 9.12m, 9.05m, 9.00m, 8.95m, 8.90m. According to the analysis of the water level data in the past 10 years, the typical dry year shows a feature of being overall lower by 0.10-0.20m, and the lower in winter and spring is more obvious; the typical wet year is overall higher, and the water level in summer and autumn is slightly higher than that in normal year. For simplicity, the average water level in dry year months is approximately set to be 0.15m lower than that in normal year, and the average water level in wet year months is approximately set to be 0.15m higher than that in normal year, i.e.

[0150]

[0151] ​​​Thus, the monthly average water levels of dry year and wet year are obtained: 8.75 m, 8.77 m, 8.80 m, 8.85 m, 8.90 m, 8.95 m, 9.00 m, 8.97 m, 8.90 m, 8.85 m, 8.80 m, 8.75 m in January-December of dry year, and 9.05 m, 9.07 m, 9.10 m, 9.15 m, 9.20 m, 9.25 m, 9.30 m, 9.27 m, 9.20 m, 9.15 m, 9.10 m, 9.05 m in January-December of wet year. The setting is consistent with the empirical rule that the actual shallow lake water level of dry year and wet year is shifted by 0.1-0.2 m, which is convenient for uniform comparison in calculation.

[0152] The micro-topography-vegetation integrated scheme obtained in Example 1 can be regarded as an initial scheme or Scheme A. In this scheme, three functional steps are arranged in a typical cross section: the submerged plant step is at an elevation of 8.60 m and has a horizontal width of about 10 m; the emergent plant step is at an elevation of 8.90 m and has a horizontal width of about 7 m; and the wetland herb step is at an elevation of 9.05 m and has a horizontal width of about 5 m. The arrangement is repeated within a range of 200 m along the shore to form a “submerged-emergent-wetland” three-level community structure. In order to analyze the performance of this scheme under different hydrological scenarios, the ecological-engineering performance of Scheme A under the scenarios of dry year, normal year and wet year is calculated according to the index system and comprehensive evaluation function given in the summary.

[0153] Taking the submerged step as an example, in the normal year, the step elevation of Scheme A is 8.60 m, and the average water depth from January to December is 0.30 m, 0.32 m, 0.35 m, 0.40 m, 0.45 m, 0.50 m, 0.55 m, 0.52 m, 0.45 m, 0.40 m, 0.35 m and 0.30 m, with an annual average water depth of about 0.41 m, falling within the optimal water depth range of 0.3-1.0 m of the submerged plant functional group , and the expected suitability score is about 0.83. In the dry year scenario, due to the overall reduction of 0.15 m in water level, the average water depth on the submerged step from January to December is 0.15-0.40 m, with an annual average of about 0.26 m, among which the water depth in January-March and November-December is only 0.15-0.20 m, close to the lower limit of suitability , and the submerged community is in a “critical shallow water” state for a long time, with reduced cold resistance and disturbance resistance; in the wet year scenario, the water depth range of the submerged step is lifted to 0.45-0.70 m, with an annual average of about 0.56 m, still belonging to The optimal range is as follows. It is evident that Scheme A is more favorable for the submerged zone in normal and wet years, but in dry years, the shallowest edge section has a shallower water depth, and the continuity of the underwater zone is significantly weakened. Analysis of emergent and wet terraces shows that in dry years, emergent terraces are exposed for many months, only submerged by shallow water of 0.05–0.10 m from May to August; conversely, in wet years, wet terraces are submerged by 0.10–0.20 m of water during the summer and autumn water levels, increasing the risk of waterlogging to wet herbaceous communities. Therefore, the same scheme exhibits an uneven distribution of ecosystem width and stability under the three scenarios.

[0154] Regarding the calculation of comprehensive indicators, this embodiment adopts the evaluation system and weight settings given in the invention. For ease of explanation, the underwater vegetation continuity index is used... Functional diversity index Transparency Improvement Potential Index Normalized value of bank slope stability safety factor and the normalized value of earthwork volume per unit shoreline Represented by 0–1 indicators, and weighted accordingly. The comprehensive evaluation function is taken as:

[0155]

[0156] in Indicates the hydrological scenario (dry year L, normal year N, or wet year H). This indicates a specific design scheme. A negative sign for the earthwork volume indicates that, all other things being equal, the design with the smaller earthwork volume is preferred.

[0157] In this embodiment, the length of the continuous submerged zone within a 200m radius along the shore, where the water depth is between 0.3 and 0.8m and the submerged plant suitability is higher than 0.7, is defined as the continuous length of the submerged zone. With 200m as the target length Calculate the underwater vegetation continuity index Calculations showed that the underwater vegetation continuity index of Scheme A under dry, normal, and wet year scenarios was [data missing]. The values ​​were approximately 0.55, 0.80, and 0.70, respectively. In dry years, due to lower water levels, parts of the submerged zone were exposed or compressed, resulting in a significant decrease in continuity. In normal water years, the continuity was best, approaching design conditions. In wet years, due to overall increased water depth and a slight shift of the suitable area towards the shore, the continuity was slightly lower than in normal water years. Functional Diversity Index Maintaining a value of approximately 0.70–0.75 across the three scenarios reflects that the three functional groups—submerged, emergent, and wetland—can maintain a certain combination under each scenario; transparency has the potential to improve. The water level is slightly lower in dry years than in normal years, mainly due to the shrinkage of the submerged zone and a reduced ability to weaken bottom sediment disturbance; the safety factor for bank slope stability is also lower. After normalization, the value remained between 0.88 and 0.90 under all scenarios, indicating a good earthwork volume index diameter. Approximately 0.42 (based on a maximum allowable earthwork volume of 1.0 for a specific project). Therefore, the comprehensive evaluation values ​​of Scheme A under the three scenarios are as follows: Dry Year Changshui Nian Flood Year According to the scenario robustness definition in this invention, that is:

[0158]

[0159] It can be seen that the robustness index of scheme A is... Its shortcomings mainly stem from the situation of dry years.

[0160] Based on this, this embodiment uses the elevation and width of the micro-topographic steps as adjustable design variables to perform robust optimization of Scheme A across multiple scenarios. While ensuring that the conditions of the riverbank road and the land use on the landside remain unchanged, adjustments to the elevations of the submerged steps, emergent steps, and wetland steps are permitted. and horizontal width The optimization objective is to ensure that the safety factor for bank slope stability is not less than 1.5 and the net earthwork volume per unit shoreline does not exceed 1.5m. 3 Maximize robustness index under the condition of / m Preferably, this embodiment uses a simplified simulated annealing algorithm for searching, taking solution A from embodiment 1 as the initial solution, and within a certain range... and A limited-amplitude perturbation is performed, and after each perturbation, the water depth-hydrodynamic conditions and ecological-engineering evaluation indicators under the three scenarios are recalculated, thereby updating the data. and In several consecutive iterations The improvement stops when it falls below the set threshold, resulting in optimization scheme B.

[0161] After several iterations, the optimized scheme B obtained in this embodiment has the following micro-topographic parameters on a typical cross-section: the elevation of the submerged step is slightly lowered to 8.55m and the width is increased to approximately 11m; the elevation of the emergent step is slightly lowered to 8.88m and the width is slightly narrowed to approximately 6.5m; the elevation of the wetland step is slightly lowered to 9.02m and the width is approximately 4.5m, while the elevations of the remaining landside slopes and shore tops remain unchanged. The purpose of lowering the submerged step by 0.05m is to increase the water depth of the outer edge section under the dry year scenario, so that the submerged zone can maintain a certain width even in the dry year; the emergent and wetland steps are slightly lowered and their widths are slightly adjusted to mitigate excessive inundation in the wet year, while also taking into account the emergent-wetland transition zone under normal water year conditions.

[0162] Recalculating the water depth under the scenarios of dry years, normal years, and wet years using the optimized parameters above reveals that: under the dry year scenario, the average water depth on the submerged step from January to December increases from 0.15–0.40m in the original scheme to approximately 0.20–0.45m, and the annual average increases from 0.26m to approximately 0.31m, which is within the range of... The shoreline width within the suitable water depth range increased significantly, and the length of the continuous submerged zone increased from approximately 110m to approximately 144m, corresponding to an underwater vegetation continuity index. The value was increased from 0.55 to approximately 0.72; under the scenario of normal water years, the water depth range of the submerged step was adjusted from 0.30–0.55m to approximately 0.35–0.60m, still completely within the range of normal water years. In the optimal zone, the continuity has been slightly improved, but the improvement is limited. Under the scenario of a wet year, the water depth range of the submerged step is adjusted from 0.45–0.70m to about 0.50–0.75m. Although it is slightly deeper, it is still within the suitable range of 0.3–1.2m. In addition, the elevation of the inner emergent step is slightly lowered, so that some water areas that are too deep to allow emergent plants to emerge are transformed into areas suitable for emergent plants, resulting in a smoother water depth gradient.

[0163] Analysis of emergent and wetland terraces shows that in dry years, the emergent terraces, due to a slight decrease in elevation, experience a prolonged shallow water period of 0.02–0.12 m from May to September, allowing emergent plants to maintain growth through root contact with groundwater even during the lowest water levels. Wetland terraces remain generally shallowly moist in dry years, without prolonged deep submersion. In wet years, the water depth of emergent terraces is concentrated between 0.17–0.32 m, while that of wetland terraces is concentrated between 0.03–0.18 m. This alleviates the situation in Scheme A, where wetland terraces experience prolonged submersion of 0.10–0.20 m, thus reducing the risk of waterlogging-induced mortality for wetland herbs. Considering all three scenarios, the optimized terrace elevation and width achieve a better balance between preventing the drying up of the submerged zone in dry years, mitigating over-inundation of the wetland zone in wet years, and maintaining stability across all three zones in normal water years.

[0164] In terms of index calculation, the underwater vegetation continuity index of optimization scheme B under three scenarios... The functional diversity index is approximately 0.72 in dry years, 0.78 in normal years, and 0.77 in wet years. Compared to Scheme A's 0.55, 0.80, and 0.70, this significantly improves performance in dry and wet years while maintaining a slightly higher level in normal years. Because the three functional groups of submerged, emergent, and wetland are more balanced in different water depth zones, the transparency potential index reaches approximately 0.76–0.78 in all three scenarios, higher than the 0.70–0.75 in Scheme A; from about 0.50 to about 0.63 in dry years, from about 0.72 to about 0.75 in normal years, and from about 0.76 to about 0.79 in wet years, reflecting the overall effect of more continuous submergent zone and more obvious wave weakening by emergent zone. Due to the moderate slope cutting and widening of the optimization scheme, the unit shoreline earthwork volume slightly increases, and the linear normalization of the optimization scheme B in the three scenarios gives from 0.42 to about 0.54, but is still lower than the preset upper limit; after recalculation of the bank slope stability, the normalized safety factor remains between 0.86 and 0.88 in the three scenarios, which is slightly lower than 0.88-0.90 of scheme A, but is higher than the minimum safety requirement.

[0165] The above indicators are brought into the comprehensive evaluation function, and the comprehensive evaluation values of the optimization scheme B in the three scenarios can be obtained, as shown in the following formula: Figure 6 about 0.63 in dry years , about 0.75 in normal years , and about 0.79 in wet years . Compared with , , of scheme A, it can be seen that the comprehensive evaluation value of the optimized scheme decreases only slightly by 0.009 in the normal year scenario, increases by about 0.076 in the dry year scenario, and increases by about 0.019 in the wet year scenario. According to the definition of the scenario robustness index, then:

[0166]

[0167] The robustness index of scheme A is , and the robustness index of scheme B is , which increases by about 14%, indicating that under the premise of not significantly increasing the earthwork volume and keeping the bank slope safety factor meeting the requirements, through multi-scenario comprehensive evaluation and parameter optimization, the overall robustness of the lake shore restoration scheme in different hydrological years can be significantly improved.

[0168] The embodiment shows that the lake shore microtopography and vegetation community integrated restoration design method proposed by the present application not only can give a reasonable microtopography-vegetation configuration scheme in a single representative year scenario, but also can optimize and compare the schemes in multiple hydrological scenarios such as dry years, normal years and wet years through a comprehensive evaluation function and a scenario robustness index, so that the final design has stronger adaptability and robustness to annual water level changes while ensuring ecological benefits and engineering safety, thereby further highlighting the technical advantages of the present application over the existing experience-based design method.

[0169] Embodiment 3: Microtopography and vegetation community integrated restoration design of a lake hard revetment section under engineering constraints.

[0170] The present embodiment selects a 150m long hard revetment section of the north shore of a city landscape lake in the same basin to illustrate how to achieve the integrated restoration design of the additional lakefront microtopography and vegetation community under the strict constraints of the existing straight or steep concrete revetment that cannot be demolished, the land side land use is tight, and the water side width is limited, etc. As shown in Figure 7 , the existing revetment is a road and straight or steep concrete panel structure, and the outside of the slope toe is a natural lake bottom. The present embodiment arranges an additional ecological step at the front edge thereof. The land side of the section is adjacent to the city main road and sidewalk, and the revetment form is mortar block + cast-in-place concrete panel structure, and the slope toe below is a natural lake bottom, and the front is an open water surface, and the small sightseeing ship is navigated all year round. The management department requires that the original revetment main structure cannot be broken, and large-scale excavation cannot be made to the land side, and the horizontal distance from the outer edge of the water side ecological structure to the original revetment toe is not more than 3.0m, so as to avoid affecting the navigation section and winter ice breaking operation, so that the microtopography reconstruction of the present embodiment can only be realized by adding a narrow ecological step and planting belt outside the original revetment toe.

[0171] According to the operation data provided by the city water department, the water level of the landscape lake is adjusted by the controlled gate, and the water level fluctuates little within a year. Taking the local elevation datum 0.00m as the reference surface, a representative year in the last 5 years is selected as the design hydrological year, and the monthly average water level elevation is about: January 10.00m, February 10.02m, March 10.05m, April 10.08m, May 10.10m, June 10.12m, July 10.15m, August 10.13m, September 10.10m, October 10.07m, November 10.05m, December 10.02m, the fluctuation amplitude is about 0.15m throughout the year, and it is basically in the "high position small fluctuation" controlled operation state. The target revetment cross section measurement shows that the backwater side pavement elevation of the sidewalk is about 10.80m, the revetment top elevation is 10.60m, and the slope section from 10.60m to 9.60m is the slope section of the cast-in-place concrete panel laid on the mortar block stone, and the slope ratio is about 1:1.5, and the slope toe elevation is about 9.60m; The range of 3-4m outside the slope toe is the natural lake bottom, and the underwater slope is gentle, from 9.60m to about 9.20m. Taking the average water level of the representative year 10.10m as an example, the original revetment in the 10.10-9.60m section is a nearly vertical hard interface above and below the water level, and in the 9.60-9.20m section, it is a natural bottom with a water depth of about 0.5-0.9m. Due to the steep hard revetment on the upper part and only one narrow deep water belt on the water side, there is almost no 0-0.3m shallow beach, resulting in sparse patches of submerged plants only in the local slope toe, and no emergent and wetland vegetation, highlighting the typical city lake straight revetment and ecological zone loss problem.

[0172] In view of the requirements of urban landscape, the target functional groups are divided into submerged plant functional group (represented by Azolla imbricata and Elodea canadensis), ornamental emergent plant functional group (represented by Acorus gramineus, Arundo donax var. variegatus and Typha minima), and riparian wetland herb functional group (represented by Iris sanguinea, sedge and dwarf wetland grass). According to the existing experiments and literature, the approximate water depth preferences of the three functional groups can be summarized as follows: The suitable water depth for the submerged plant functional group is about 0.4-1.0 m. If the water depth is less than 0.3 m, the light is too strong, which can cause the attached algae to multiply rapidly and the plants to die by floating in summer. If the water depth is more than 1.2 m, the light is insufficient, which can cause the plants to grow poorly; The suitable water depth for the emergent plant functional group is about 0.1-0.3 m. The root base part requires to be in shallow water or saturated soil for a long time, and the stems and leaves are out of the water to form a dense belt; The suitable state for the wetland herb functional group is a high water content zone near the normal water level ±0.1-0.2 m. The plants can grow under the condition of short-term submergence, but they are not resistant to long-term submergence of more than 0.3 m. Since the lake is a city storage lake, the wave conditions are relatively weak, and the representative effective wave height is about 0.15-0.25 m. The water dynamic exposure index is not high as a whole. In this embodiment, the suitability of each functional group is mainly controlled by water depth and submergence frequency, and the wave factor is only considered as a secondary disturbance.

[0173] Under the strict engineering constraints, the parameterized micro-topography design method of the present application is used to control the additional micro-topography within the range of 0-2.5 m from the water side of the original revetment slope foot. Considering the site conditions and the navigation clearance of the ship, a two-stage ecological step is designed on the outside of the original revetment slope foot by means of a reinforced concrete cantilever plate and a steel pile support: one underwater step for submerged plants, and one shallow water step for emergent plants. A narrow wetland flower groove is also set on the water side of the revetment top to simulate the wetland zone. The structure top elevation of the submerged plant step is set to 9.50 m, and it is continuously arranged along the shore for 150 m with a horizontal width of 2.0 m, i.e. extending outward by 2.0 m from the original slope foot, and the soil thickness on the plate is about 0.40 m. The planting medium is light medium mixed with river sand to reduce the self-weight. The top elevation of the emergent plant step is set to 9.85 m, and the horizontal width is 1.0 m. It is connected with the upper revetment panel through a stepped support, and the surface is also covered with soil about 0.40 m thick, and overflow holes are provided to communicate with the water below. A strip-shaped flower groove with a width of 0.80 m and a depth of 0.30 m is set on the inner edge of the revetment top, with an elevation of about 10.55 m. The wetland herb zone is maintained by rainwater and drip irrigation , which is no longer a strict micro-topography step involved in water depth calculation, but it supplements the riparian vegetation layer in the overall community structure.

[0174] Based on the above micro-topographic parameters, the water depth conditions of the two-stage water side steps in the representative year are calculated according to the method of the present application. The submerged step elevation is 9.50 m, and the monthly average water depth is , and the average water depth of 1-12 months is about 0.50 m, 0.52 m, 0.55 m, 0.58 m, 0.60 m, 0.62 m, 0.65 m, 0.63 m, 0.60 m, 0.57 m, 0.55 m, 0.52 m, and the annual average water depth is:

[0175]

[0176] The maximum is about 0.65 m, the minimum is about 0.50 m, the water depth variation range in the whole year is about 0.15 m, always in the target range of 0.4-1.0 m, and the fluctuation is relatively mild, which is suitable for building continuous submerged plant zone. The elevation of the emergent step is 9.85 m, and the monthly average water depth is , so the average water depth of 1-12 months is about 0.15 m, 0.17 m, 0.20 m, 0.23 m, 0.25 m, 0.27 m, 0.30 m, 0.28 m, 0.25 m, 0.22 m, 0.20 m, 0.17 m, and the annual average water depth is:

[0177]

[0178] The water depth variation range in the whole year is 0.15-0.30 m, which almost completely falls in the optimal interval of the emergent plant functional group , which not only ensures long-term root infiltration, but also does not form high water level waterlogging which is not conducive to the use function of urban shore. Since the lake water level is controlled, the extreme low water level is generally not lower than 9.95 m, even during the short-term storage or maintenance period, the submerged step can still maintain a water depth of at least 0.30-0.35 m, and the emergent step will not be completely dried, which is of great significance to maintain stable shore vegetation of urban landscape lake.

[0179] Under the above hydrological-micro-topographic conditions, the suitability level of different steps and can be quantitatively estimated by applying the vegetation functional group suitability response model proposed in the present application. Since the hydrodynamic exposure is weak in the present embodiment, it can be considered in a simplified condition that is in the medium-low exposure interval, and the contribution to the suitability function is small, which is mainly determined by the water depth . Taking the submerged step as an example, the response function of Based on empirically fitted parameters, the suitability value for most months of the year is around 0.80–0.90, with an annual average of around 0.85; the emergent step is within a water depth range of 0.15–0.30m. response function The average annual suitability is approximately 0.82. Considering the 150m length along the shoreline and the continuous layout of the two steps, the length of the "continuous usable strip" provided in this embodiment is basically equal to the shoreline length. If 150m is taken as the target length... The continuous length of the submerged zone Reaching depths of 140–150m (with slight interruptions in the location of local inlet and outlet water facilities), corresponding to an underwater vegetation continuity index. It is far higher than the state before the transformation, which was almost zero.

[0180] In terms of engineering quantity and stability, the submerged step is 2.0m wide and the emergent step is 1.0m wide, with a planting substrate thickness of approximately 0.40m for both, and a planting substrate density of approximately 1.6 t / m³. 3 Converted, the filling volume per unit shoreline length is approximately The total filling volume corresponding to a 150m shoreline is approximately 180m³. 3 This is a medium-scale additional structural engineering project. Since the two-tiered steps are anchored to the existing revetment panels and foundations using steel piles and cantilever slabs, the original slope's stress conditions are not altered. The additional bending moment generated by their self-weight on the revetment structure can be controlled within the original design safety reserve during design calculations. It only has a minor covering effect on the underwater natural slope and will not induce deep-seated sliding damage. Through simplified structural analysis and slope stability verification, under normal operating water conditions, the ecological steps and planting loads in this embodiment reduce the safety factor of the original revetment structure from approximately 1.80 to approximately 1.65, still higher than the standard requirement of 1.50. Considering the combined effects of high summer water levels and wave action, the safety factor is no less than approximately 1.55, meeting the long-term operational safety requirements of urban lake shores.

[0181] In terms of vegetation configuration, this embodiment employs a combination of pre-cultivated block-shaped grass mats and on-site planting on submerged terraces to lay submerged plants such as *Hydrilla verticillata* and *Elodea nuttallii*. The initial planting coverage is controlled at 50–60%, and it is expected that 70–80% continuous underwater vegetation coverage can be formed by the end of the first growing season. On emergent terraces, *Iris tectorum* and *Typha orientalis* are the main plants, supplemented by a small amount of *Arundinaria variegata* and other ornamental emergent plants, using a combination of clump planting and strip planting, with an initial planting density of approximately 4 plants / m². 2; the water edge iris, dwarf sedge and water-tolerant lawn plants are planted in the wetland flower groove on the top of the revetment, forming a landscape continuous revetment green belt. According to the above water depth-environment response analysis, it is predicted that in 2-3 years, the hard revetment section can be changed from the current state of "bare concrete panel + a small amount of algae underwater" to "three-level vegetation structure of lower continuous submerged zone + middle emergent zone + upper wetland herb zone", which significantly improves the ecological function and landscape quality of the urban lake shore without changing the main structure of the original revetment and without significantly increasing the earthwork.

[0182] This embodiment shows that even under the condition of urban lake hard revetment where the revetment structure cannot be removed, the land side cannot be excavated, and the water side expansion is strictly limited, the method proposed by the application can still match the water depth-flooding process with the environmental response of the functional group of vegetation by optimizing the parameters of the additional step height, width and the like under strict constraints, realizing the integration of local micro-topography reconstruction and community reconstruction on the water side. Compared with the traditional method of hanging pots or local block planting on the concrete panel, the technical solution of this embodiment uses water depth-water level data and functional group suitability model to make the micro-topography-vegetation combination in a limited width have higher hydrological adaptability and spatial continuity.

[0183] Those skilled in the art can understand that all or part of the steps in the above-mentioned embodiment method can be completed by programs instructing related hardware, therefore, the present application can adopt a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer usable storage media (including but not limited to disk memory, CD-ROM, optical memory, etc.) containing computer usable program codes.

[0184] Each of the embodiments in the specification is described in a progressive manner, and each embodiment focuses on the difference from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the above embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and the relevant parts can be referred to the part of the method embodiment.

[0185] The above embodiments have been described in detail, and the principles and implementation modes of the application have been described by applying specific examples; the above embodiment descriptions are only used to help understand the method of the application and its core idea; at the same time, for those skilled in the art, according to the idea of the application, the specific implementation mode and application range can be changed; in view of the above, the content of the specification should not be understood as a limitation of the application.

Claims

1. A lake shore zone ecological restoration method based on the integration of micro-topography and vegetation community, characterized in that, The method comprises the following steps: S1, obtaining the basic data of the target water body under the same elevation reference, and dividing the target water body into several shore sections containing multiple design units along the shoreline direction of the lake shore; S2, constructing the water depth time series of each design unit on a multi-year scale according to the basic data, and calculating the hydrodynamic exposure index for representing the wave energy and flow velocity shear intensity of each design unit; S3, obtaining the survival rate, coverage or aboveground biomass data of the candidate vegetation functional group under different water depths and hydrodynamic exposure indexes, and fitting the data to obtain the environmental response curve of each candidate vegetation functional group, and obtaining the suitability score function under the given water depth-hydrodynamic combination; S4, parameterizing the microtopography of each design unit to form a microtopography parameter vector, and calculating the corrected water depth and corrected hydrodynamic exposure index of each design unit under the typical water level condition after applying the microtopography; S5, predicting the vegetation suitability, expected coverage and community continuity of each design unit under the corrected water depth and corrected hydrodynamic exposure index based on the suitability score function, and constructing a functional response model for realizing the quantitative matching of microtopography steps and vegetation community by combining the ecological function index, and the specific process comprises the following steps: The steps of each level corresponding to the micro-topography in the design unit are regarded as potential vegetation zones, and the corrected water depth and the corrected hydrodynamic index are calculated on each step The suitability score of different vegetation functional groups is calculated by substituting the suitability score function The suitability score of different vegetation functional groups is calculated by substituting the suitability score function The suitability score of different vegetation functional groups is calculated by substituting the suitability score function The suitability score of different vegetation functional groups is calculated by substituting the suitability score function Select 2-3 vegetation functional groups with high score of suitability on the step and strong functional complementarity Carry out community combination design to form submerged-float leaf-emersed-wetland gradual structure in vertical direction; Based on the slope gradient, soil shear strength and hydrodynamic exposure index, the safety factor of the bank slope is calculated by using the conventional slope stability analysis method and the safety factor of the bank slope is defined as the safety threshold of the bank slope that is: ； wherein, is the anti-sliding force or anti-sliding torque, is the sliding force or sliding torque; Comparing the original terrain with the target micro-terrain elevation, combined with soil density calculation of unit shoreline earthwork ; Constructing a functional response model for realizing the quantitative matching of microtopography steps and vegetation community, that is: ； wherein, are weight coefficients, and satisfy ; The ecological function index at least includes: Ecological indicators: including an underwater vegetation continuity index along a water depth gradient , a vegetation functional type diversity index , and an expected transparency improvement index ; Engineering indicators include bank stability factor of safety , slope stability factor of safety, and scour resistance to extreme flood scenarios; Management index: including unit shoreline length earthwork , unit function to promote the corresponding project cost and post-maintenance workload score; S6, calculating the comprehensive evaluation function under multiple hydrological scenarios based on the functional response model and defining the scenario robustness index, and obtaining the lake shore ecological restoration scheme of microtopography and vegetation community integration through iterative search or heuristic combinatorial optimization method.

2. The method for ecological restoration of the riparian zone according to claim 1, characterized in that, The basic data includes multi-year water level sequence of the target water body and topographic data and bottom material parameters of the present situation of the lake shore; The multi-year water level sequence includes daily or hourly water level observation values for no less than 5 consecutive years to reflect the water level fluctuation characteristics of typical dry years, normal years and wet years; The terrain data includes data acquired through measurement cross-sections, RTK surveying, or UAV lidar, and discretized into regular grids or cross-section points in a geographic information system. The elevation of the grid center is denoted as [elevation value missing]. ; The bottom material parameters include soil type, natural unit weight, cohesion and internal friction angle for slope stability analysis.

3. The method for ecological restoration of the riparian zone according to claim 1, characterized in that, In step S2, the specific process comprises the following steps: In each shore section, multiple design units are divided along the vertical shore line direction with equal or variable elevation intervals, and each design unit is characterized by representative elevation , slope and horizontal width. By time step Calculate the instantaneous water depth of each design unit Construct the water depth time series , and count the instantaneous water depth in the whole year The frequency of falling into the preset interval forms the water depth frequency distribution ; Sequentially scanned water depth time series , identifying consecutive flooding time periods and consecutive emergence time periods , forming a flooding duration distribution for limiting the flooding tolerance upper limit of submerged plants or evaluating the adaptation of emergent and helophytic plants to dry-wet alternation and emergence duration distribution ; Based on the time series of water depth The water power exposure index to characterize the relative water dynamic strength of each design unit is calculated based on the average value of the water depth That is: ； wherein is the water power exposure index of the design unit is the representative significant wave height of the design unit is the representative water depth of the design unit is the representative slope of the design unit is the representative average water depth of the design unit is the representative slope of the design unit is the representative average water depth of the design unit is the representative slope of the design unit 4. The method for ecological restoration of the riparian zone according to claim 1, characterized in that, In step S3, the specific process comprises the following steps: establishing candidate vegetation functional groups, at least including one or more of a submerged plant functional group, a floating leaf plant functional group, an emergent plant functional group and a riparian wetland herbaceous functional group, each candidate vegetation functional group comprising one or more representative species; Through transect surveys or water and flow control experiments along the lakeshore, at a series of water depths... With hydrodynamic exposure index Determining the functional groups of each vegetation under certain conditions Survival rate, canopy cover, or aboveground biomass were measured, and these observations were normalized into a fitness score. The range of values ​​is ; The environmental response curves of each candidate vegetation functional group are fitted using logistic regression or generalized linear models, and an environmental suitability score function is established to represent the environmental suitability of the candidate vegetation functional group in a given water depth-water dynamic combination a suitability score function of the lower suitability, i.e.: ； wherein, is the first suitability score of the candidate vegetation functional group under water depth , hydrodynamic exposure index conditions, and are parameters fitted from monitoring or experimental data. Suitability score Water depth - hydrodynamic combination above a preset threshold As a vegetation functional group Preferred planting condition interval, i.e.: When the suitability score Corresponding to the water depth - hydrodynamic combination Preferred habitat interval for the vegetation functional group Suitable for focused planting; When the suitability score Below threshold 0.3, considered unsuitable area, not selected in colony configuration.

5. The method for ecological restoration of the riparian zone according to claim 1, characterized in that, In step S4, the specific process comprises the following steps: The micro-terrain of each design unit is represented by a design parameter vector, i.e. a micro-terrain parameter vector is: ； wherein, is the target elevation of the nth level or ramp segment, is the corresponding horizontal width, is the corresponding slope, is the number of microterrain levels within the design unit, i.e., the number of levels. The modified water depth of each step after micro-topography reconstruction is calculated by geometric relationship under typical water level conditions i.e. ； wherein is time corresponding water level observation; updating the water depth frequency distribution and the duration of inundation distribution for each level of step, and correcting the hydrodynamic exposure index based on the updated average water depth and local slope , obtaining the modified hydrodynamic exposure index for the vegetation functional group suitability prediction .

6. The method for ecological restoration of the riparian zone according to claim 1, characterized in that, In step S6, the specific process comprises the following steps: At least three representative hydrological scenarios are selected, which are dry year scenario , normal year scenario , and wet year scenario , and weights are assigned to each scenario ; For any candidate microtopography and vegetation community combination , the integrated evaluation function of each scenario is calculated The formula for calculating the integrated evaluation function is: ； wherein, is the scenario is the underwater vegetation continuity index, is the functional diversity index, is the transparency improvement potential indicator, is the bank slope safety factor, is the earthwork volume indicator, is the weight coefficient; According to the comprehensive evaluation function Defining the scenario robustness index including the minimum or weighted average of the comprehensive evaluation function under the water intake scenarios, expressed as: ； Or ； wherein are the weights for each scenario, satisfying ; Under the premise of constraints, maximize the scenario robustness index For the target, the candidate micro-topography and vegetation community combination is optimized by iterative search or heuristic combinatorial optimization method The integrated lake shore zone ecological restoration scheme of micro-topography and vegetation community is obtained by joint optimization. The expression of the constraint condition is: ； wherein, is a bank slope safety threshold, is a earthwork volume index threshold.

7. The method for ecological restoration of the riparian zone according to claim 1, characterized by the fact that, Between step S5 and step S6, the following steps are also included: Based on the vertical light attenuation coefficient and the surface light intensity, the light intensity at different water depths is estimated , the expression is: ； wherein, is the water surface light intensity, is the total light attenuation coefficient, is the water depth; The specified planting depth for submerged plants is [not specified]. Light intensity at the location Not lower than the light compensation point of the candidate vegetation functional group ,Right now: ； For water depth-topography combinations not meeting the above conditions are considered as not suitable for planting submerged plants under transparency conditions and a penalty factor is introduced in the calculation of the suitability score , forcing the suitability score down or to 0.

8. The method for ecological restoration of the riparian zone according to claim 1, characterized in that, It also includes repeating the layout of several microtopography-vegetation combination modules along the shoreline direction of the lake shore with design units as the scale, and each microtopography-vegetation combination module at least includes: The gentle slope deep water platform located in the perennial deep water level interval for planting submerged plants; The middle water step located in the seasonal flooding interval for planting floating leaf plants and emergent plants; The shallow water step or shore gentle slope located in the intermittent flooding or shore edge flooding area for planting wet grass and shrubs; The elevation and width of each step and gentle slope are set according to the lake shore ecological restoration scheme of multiple hydrological scenarios, so that the continuity of underwater vegetation zone and the overall stability of shore slope structure can be maintained in dry year, normal year and wet year scenarios.

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