Construction method of multi-dimensional stepped river ecological flow

Abstract

The invention discloses a multi-dimensional stepped river ecological flow construction method, which comprises the following steps: constructing a water balance equation, and calculating ecological flow for maintaining river communication; after the water body communication function of the river is restored, the ecological flow of the river in different time periods in the year is calculated through a hydrology Tennant method; after the natural hydrological rhythm of the river is restored, hydraulics and ecology are fused, and sensitive ecological flow of protected species is superposed in a river ecological system; and after the sensitive ecological flow of the protected species is superposed in the river ecological system, the river channel bed forming flow is determined. The method is suitable for river ecosystem requirements of different recovery stages or different inflow situations, and ecological flow schemes with low standards, medium standards and high standards differentiated are provided; according to the method, multiple dimensions can be comprehensively considered, the river ecological flow requirements of different incoming water conditions and different recovery stages are met, accurate management and regulation of the river ecological flow are achieved, and powerful support is provided for comprehensive recovery and sustainable development of a river ecological system.

Description

Technical Field

[0001] The present invention belongs to the technical field of river ecosystems, and specifically relates to a method for constructing a multi-dimensional stepped river ecological flow. Background Art

[0002] As an important part of nature, the health and stability of river ecosystems are directly related to biodiversity, water resources security and the sustainable development of human society. However, with the intensification of human activities, river ecosystems are facing serious threats, such as reduced water volume, changes in hydrological rhythms, and loss of biodiversity. In order to ensure the comprehensive recovery and sustainable development of river ecosystems, it is particularly important to build a coupled calculation system that integrates hydrology, hydraulics, ecology and other disciplines. At present, there are many methods for calculating river ecological flow, but most of them have problems of singleness and one-sidedness, and cannot fully meet the multi-dimensional ecological needs of river ecosystems. Therefore, there is an urgent need for a step-by-step river ecological flow construction method that can comprehensively consider multiple dimensions. Summary of the invention

[0003] The purpose of the present invention is to provide a method for constructing a multi-dimensional stepped river ecological flow in response to the above-mentioned deficiencies in the prior art, so as to solve the problem that the existing river ecological flow calculation method is single and one-sided and cannot fully meet the multi-dimensional stepped needs of the river ecosystem.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is:

[0005] A method for constructing a multi-dimensional stepped river ecological flow includes the following steps:

[0006] S1. Construct a water balance equation to calculate the ecological flow required to maintain river connectivity, thereby restoring the connectivity of river water bodies;

[0007] S2. After the river restores its water connectivity function, the hydrological Tennant method is used to calculate the ecological flow of the river at different times of the year, thereby restoring the natural hydrological rhythm of the river;

[0008] S3. After restoring the natural hydrological rhythm of the river, integrate hydraulics and ecology to superimpose sensitive ecological flows of protected species in the river ecosystem;

[0009] S4. Determine the river bed-forming flow after superimposing the sensitive ecological flow of protected species in the river ecosystem.

[0010] Furthermore, in S1, the water balance equation is:

[0011]

[0012] Among them, Qi , Q i+1 are the runoff of upper section i and lower section i+1 respectively; Q tg is the average evaporation and infiltration flow rate during the water replenishment process; Q y is the average diversion flow during the water replenishment process; W 0 , W T+Ty are the water storage capacity of the river section at time 0 and time T+Ty respectively;

[0013] The river channel storage filling volume (W T+Ty -W 0 ) and the average evaporation and infiltration flow rate during the water replenishment process. tg Unknown parameters;

[0014] The calculation is used for the simulation process of the lower section i+1 after the river channel is full and the evaporation and infiltration losses of the river channel are taken into account. The simulated runoff Q of the lower section i+1 is i+1 The goal is to minimize the error with the measured runoff and calibrate the average evaporation and infiltration flow rate during the water replenishment process. tg The average evaporation and infiltration flow rate during the water replenishment process is obtained as evaporation and infiltration flow rate Q tg Ecological flow as a function of water connectivity in corresponding river segments.

[0015] Furthermore, in S2, the hydrological Tennant method is used to calculate the ecological flow Qe of the river at different times of the year. t ,include:

[0016]

[0017] Among them, Q t,j is the natural runoff in the tth month of the jth year after the restoration of a control section of the river; N is the length of the restoration series; α i It is the ratio of the multi-year average flow.

[0018] Furthermore, in S3, protecting species-sensitive ecological flows includes:

[0019] protected species-sensitive ecological flows in mountain rivers;

[0020] sensitive ecological flows of protected species in terrestrial ecological conservation targets of riparian zones;

[0021] sensitive ecological flows of protected species for aquatic ecological protection goals;

[0022] Protected species sensitive ecological flows in plain rivers.

[0023] Furthermore, the wetted perimeter method or one-dimensional hydrodynamic model was used to calculate the sensitive ecological flows of protected species in mountain rivers.

[0024] Furthermore, the wetted perimeter method was selected to calculate the sensitive ecological flows of protected species for the terrestrial ecological protection targets in the riparian zone;

[0025] The river topography data of the protected species habitat and the water flow simulation under different flow rates were collected, the relationship curve between wetted perimeter and flow rate was analyzed, and the flow rate corresponding to the inflection point on the wetted perimeter-flow rate curve of the shallow section was used as the sensitive ecological flow of the protected species.

[0026] Furthermore, a one-dimensional hydrodynamic model is used to calculate the sensitive ecological flows of protected species for aquatic ecological protection targets.

[0027] Furthermore, the sensitive ecological flow of protected species in plain rivers is calculated, including the following sub-steps:

[0028] A1. Construct the relationship curve between physical variables and biological variables of plain rivers - habitat suitability curve HSC;

[0029] A2. Use a two-dimensional hydrodynamic model to calculate the output water depth and flow velocity, and calculate the suitability index of each node on the grid through the habitat suitability curve HSC, including the habitat water depth suitability index DHSI of each node and the habitat flow velocity suitability index VHSI of each node, and then draw habitat quality zoning maps of water depth and flow velocity respectively;

[0030] A3. Calculate the comprehensive index of habitat suitability:

[0031]

[0032] Among them, GHSI is a comprehensive indicator of habitat suitability;

[0033] A4. Based on the comprehensive habitat suitability index GHSI, the sensitive ecological flow of protected species is evaluated.

[0034] Furthermore, in said S4, the flow rate for river channel bed construction is determined, specifically: the planned regulation flow rate of the main channel of the river channel is used as the flow rate for river channel bed construction.

[0035] The method for constructing a multi-dimensional stepped river ecological flow provided by the present invention has the following beneficial effects:

[0036] 1. The present invention constructs a coupled calculation system integrating hydrology, hydraulics, ecology and other disciplines to scientifically and systematically determine the reasonable ecological flow required for rivers at different recovery stages to ensure the comprehensive recovery and sustainable development of river ecosystems.

[0037] 2. The present invention provides an ecological flow calculation method that can comprehensively consider multiple dimensions such as river historical hydrological data, topography, and biome characteristics; through a coupled calculation system, it can achieve precise management and regulation of river ecological flow and promote the self-regulation and recovery ability of river ecosystems;

[0038] 3. The present invention adapts to the needs of river ecosystems at different recovery stages or different water inflow situations, and proposes differentiated ecological flow plans with low, medium and high standards; it can comprehensively consider multiple dimensions, adapt to the river ecological flow needs at different water inflow situations and different recovery stages, realize precise management and regulation of river ecological flow, and provide strong support for the comprehensive recovery and sustainable development of river ecosystems. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a flow chart of the method for constructing the multi-dimensional stepped river ecological flow of the present invention. DETAILED DESCRIPTION

[0040] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0041] Example 1

[0042] This embodiment provides a method for constructing a multi-dimensional stepped river ecological flow. This embodiment is a method for constructing a multi-dimensional stepped river ecological flow that can comprehensively consider multiple dimensions and can fully meet the multi-dimensional ecological needs of the river ecosystem. Figure 1 , which specifically includes the following:

[0043] Step S1, constructing a water balance equation to calculate the ecological flow required to maintain river connectivity, thereby restoring the connectivity function of the river water body;

[0044] For perennially dry rivers, river infiltration is relatively strong, and restoring the water body connectivity function is the primary goal. This embodiment uses the water balance method to analyze the flow required to maintain the river water body connectivity function. By establishing a water balance equation between the inflow, outflow, storage change, and evaporation and infiltration of the river section, the ecological flow to maintain the river connectivity is calculated;

[0045] Assuming that the water replenishment is from time 0 to time T, the propagation time from the upper section i to the lower section i+1 is Ty, and the water balance equation of the river section i is:

[0046]

[0047] Among them, Q i , Q i+1 are the runoff of upper section i and lower section i+1 respectively; Q tg is the average evaporation and infiltration flow rate during the water replenishment process; Q y is the average diversion flow during the water replenishment process; W 0 , W T+Ty are the water storage capacity of the river section at time 0 and time T+Ty respectively;

[0048] In the specific calculation, the average evaporation and infiltration flow Q during the water replenishment process is analyzed through the flow monitoring data of the upstream and downstream sections during the water replenishment period. tg , and use it as the ecological flow to maintain the connectivity of the water body in this section of the river. In the process of water flow evolution, the water flow can only continue to move after the upstream rivers and lakes are full. Therefore, the initial loss of flow in the upper section is mainly used for filling the river channel, and then mainly for evaporation and infiltration losses in the river.

[0049] Based on this, the channel storage filling volume (W T+Ty -W 0 ) and the average evaporation and infiltration flow rate during the water replenishment process. tg Unknown parameters;

[0050] The calculation is used for the simulation process of the lower section i+1 after the river channel is full and the evaporation and infiltration losses of the river channel are taken into account. The simulated runoff Q of the lower section i+1 is i+1 The goal is to minimize the error with the measured runoff and calibrate the average evaporation and infiltration flow rate during the water replenishment process. tg The average evaporation and infiltration flow rate during the water replenishment process is obtained as evaporation and infiltration flow rate Q tg Ecological flow as a function of water connectivity in corresponding river segments.

[0051] Step S2, after the river restores its water body connectivity function, the hydrological Tennant method is used to calculate the ecological flow of the river at different times of the year, thereby restoring the natural hydrological rhythm of the river;

[0052] On the basis of restoring the connectivity of water bodies, we further restored their natural hydrological rhythm. We selected the hydrological Tennant method, set different ecological environment status levels, and used historical hydrological data to calculate the ecological flow Qe at different times of the year. i , used to restore the natural hydrological rhythm of rivers:

[0053]

[0054] Among them, Q t,j is the natural runoff in the tth month of the jth year after the restoration of a control section of the river; N is the length of the restoration series; α iIt is the ratio of the multi-year average flow.

[0055] Step S3, after restoring the natural hydrological rhythm of the river, integrating hydraulics and ecology, and superimposing sensitive ecological flows of protected species in the river ecosystem;

[0056] Sensitive ecological flows are essential for maintaining the survival and reproduction of protected species in river ecosystems at different growth stages, and mainly include:

[0057] 1. For mountain rivers, the wetted perimeter method or one-dimensional hydrodynamic model can be used to calculate the sensitive flow of protected species. Since the wetted perimeter method or one-dimensional hydrodynamic model is an existing technology, their detailed process will not be described in detail.

[0058] 2. For the terrestrial ecological protection goals in the riparian zone, the wetted perimeter method is selected to calculate the ecological water demand of the protected species during the sensitive period. By collecting the river topography data of the habitat and simulating the water flow under different flow rates, the relationship curve between the wetted perimeter and the flow rate is analyzed. The flow rate corresponding to the inflection point on the wetted perimeter-flow curve of the shallow section is used as the recommended ecological flow value, which can ensure that the plant roots obtain appropriate water supply.

[0059] 3. For the aquatic ecological protection goal, a one-dimensional hydrodynamic model is selected to simulate the flow conditions of the river, and the corresponding ecological flow is calculated based on the requirements of the protected species for flow conditions (flow velocity, water depth, etc.) during the sensitive period.

[0060] 4. For plain rivers, especially those where rivers and lakes are connected in series, a hydraulic and ecological coupling method is used, that is, an ecological flow calculation method based on habitat evaluation and two-dimensional hydrodynamic simulation. The hydraulic conditions are linked to habitat suitability to evaluate the response of indicator species to ecological flow, which can be used to construct water flow habitat conditions that meet the needs of restoring indicator species.

[0061] The specific steps are as follows:

[0062] A1. First, to construct the habitat suitability curve HSC, it is necessary to obtain it through field surveys. Under the conditions of different flow velocities and water depths, the abundance of specific protected species is investigated, and the relationship curve between physical variables (flow velocity, water depth, etc.) and biological variables (abundance) is established. That is, the relationship curve between the physical variables and biological variables of plain rivers - the habitat suitability curve HSC is constructed, which can reflect the needs of specific fish species for habitat factors such as flow velocity and water depth during their life history stages.

[0063] A2. Use the two-dimensional hydrodynamic model to calculate the output data (water depth, flow velocity), and calculate the suitability index of each node on the grid through the habitat suitability curve HSC. For water depth, the habitat water depth suitability index DHSI of each node can be calculated. For flow velocity, the habitat flow velocity suitability index VHSI of each node can be calculated. Both DHSI and VHSI are dimensionless values ​​with a value range of 0 to 1.0. Based on the calculation results, habitat quality zoning maps of water depth and flow velocity can be drawn respectively.

[0064] A3. Calculate the comprehensive habitat suitability index GHSI. The geometric mean of DHSI and VHSI can be calculated at each node of the computational grid:

[0065]

[0066] Where: GHSI is the comprehensive index of habitat suitability; DHSI is the habitat water depth suitability index; VHSI is the habitat flow velocity suitability index.

[0067] A4. Based on the comprehensive habitat suitability index GHSI, the sensitive ecological flow of protected species is evaluated.

[0068] Step S4, after superimposing the sensitive ecological flow of protected species in the river ecosystem, determine the river bed-building flow;

[0069] Flood frequency analysis is an important method in hydrology. Using a flood process Qp with a certain frequency flow as the bed-forming flow can have a significant shaping effect on the riverbed morphology. If the flow is too large, it will produce artificial floods and have a significant destructive effect on the shore zone; if it is too small, it will not play a role in shaping the riverbed morphology. Considering that the main channel is the main channel for daily runoff, its stability is crucial to the health of the river and the balance of the ecosystem. Therefore, this embodiment uses the planned regulation flow of the main channel as the riverbed-forming flow, and the flood discharge standard as the bed-forming flow standard.

[0070] This embodiment further proposes a stepped ecological flow

[0071] In order to achieve scientific and reasonable ecological flow management and deeply integrate the diversified water demand of human economic and social development with the ecological water demand necessary for the recovery of river ecosystems, low-standard, medium-standard and high-standard ecological flow plans that emphasize both sustainability and resilience are proposed. They can meet the ecological flow control needs under different hydrological situations and different recovery stages, and ensure that the river ecosystem can maintain its stability and resilience when facing natural changes and human interference, while promoting the fair, efficient and sustainable use of water resources.

[0072] Low-standard ecological flow plan: As the basic starting point for ecological restoration, it focuses on the bottom-line goal of "full connection" and uses the water balance method to calculate the basic flow to ensure that the river can maintain a certain amount of water in any season and provide the most basic living conditions for the ecosystem.

[0073] Medium standard ecological flow scheme: With the goal of "restoring hydrological rhythm", it uses hydrological methods to calculate suitable ecological flow processes that can reflect the characteristics of natural hydrological cycles, simulates seasonal flow changes in rivers under natural conditions, supports more complex ecological processes in ecosystems, and promotes the self-regulation and self-recovery capabilities of river ecosystems.

[0074] High-standard ecological flow: As an advanced stage of ecological restoration, with the goal of "biodiversity maintenance and restoration", on the basis of appropriate ecological flow processes, a calculation method that integrates hydraulics and ecology is adopted to superimpose the flow during sensitive periods of protected species, such as flow requirements during key ecological events such as fish spawning and habitat, so as to comprehensively promote the improvement of river biodiversity and the overall health of the ecosystem.

[0075] For bed-forming flow, we should combine the shrinkage of the main channel of the river and the water storage of upstream water conservancy projects, and carry out pulse water replenishment at a bed-forming flow rate that occurs once every 1 to 3 years.

[0076] Although the specific implementation of the invention is described in detail in conjunction with the drawings, it should not be understood as limiting the scope of protection of this patent. Within the scope described in the claims, various modifications and variations that can be made by those skilled in the art without creative work still fall within the scope of protection of this patent.

Claims

1. A method for constructing multi-dimensional stepped river ecological flow, characterized in that: The following steps are involved: S1. Construct a water balance equation to calculate the ecological flow required to maintain river connectivity, thereby restoring the connectivity of river water bodies; S2. After the river restores its water connectivity function, the hydrological Tennant method is used to calculate the ecological flow of the river at different times of the year, thereby restoring the natural hydrological rhythm of the river; S3. After restoring the natural hydrological rhythm of the river, integrate hydraulics and ecology to superimpose sensitive ecological flows of protected species in the river ecosystem; S4. Determine the river bed-forming flow after superimposing the sensitive ecological flow of protected species in the river ecosystem.

2. The method for constructing multi-dimensional stepped river ecological flow according to claim 1 is characterized in that: In S1, the water balance equation is: Among them, Q i , Q i+1 are the runoff of upper section i and lower section i+1 respectively; Q tg is the average evaporation and infiltration flow rate during the water replenishment process; Q y is the average diversion flow during the water replenishment process; W0, W T+Ty are the water storage capacity of the river section at time 0 and time T+Ty respectively; The amount of storage in the river channel (W T+Ty -W0) and the average evaporation and infiltration flow rate during the water replenishment process evaporation and infiltration flow rate Q tg Unknown parameters; The calculation is used for the simulation process of the lower section i+1 after the river channel is full and the evaporation and infiltration losses of the river channel are taken into account. The simulated runoff Q of the lower section i+1 is i+1 The goal is to minimize the error with the measured runoff and calibrate the average evaporation and infiltration flow rate during the water replenishment process. tg The average evaporation and infiltration flow rate during the water replenishment process is obtained as evaporation and infiltration flow rate Q tg Ecological flow as a function of water connectivity in corresponding river segments.

3. The method for constructing multi-dimensional stepped river ecological flow according to claim 1 is characterized in that: In S2, the hydrological Tennant method is used to calculate the ecological flow Qe of the river at different times of the year. t ,include: Among them, Q t,j is the natural runoff in the tth month of the jth year after the restoration of a control section of the river; N is the length of the restoration series; α i It is the ratio of the multi-year average flow.

4. The method for constructing multi-dimensional stepped river ecological flow according to claim 1 is characterized in that: S3, protecting species-sensitive ecological flows, includes: sensitive ecological flows of protected species in mountain rivers; sensitive ecological flows of protected species in terrestrial ecological conservation targets of riparian zones; sensitive ecological flows of protected species for aquatic ecological protection goals; Sensitive ecological flows of protected species in plain rivers.

5. The method for constructing multi-dimensional stepped river ecological flow according to claim 4 is characterized in that: The wetted perimeter method or one-dimensional hydrodynamic model was used to calculate sensitive ecological flows of protected species in mountain rivers.

6. The method for constructing multi-dimensional stepped river ecological flow according to claim 4 is characterized in that: The wetted perimeter method was selected to calculate the sensitive ecological flow of protected species for terrestrial ecological protection targets in riparian zones; The river topography data of the protected species habitat and the water flow simulation under different flow rates were collected, the relationship curve between wetted perimeter and flow rate was analyzed, and the flow rate corresponding to the inflection point on the wetted perimeter-flow rate curve of the shallow section was used as the sensitive ecological flow of the protected species.

7. The method for constructing multi-dimensional stepped river ecological flow according to claim 4 is characterized by: A one-dimensional hydrodynamic model is used to calculate sensitive ecological flows of protected species for aquatic ecological protection targets.

8. The method for constructing multi-dimensional stepped river ecological flow according to claim 4 is characterized in that: Calculation of sensitive ecological flows of protected species in plain rivers includes the following sub-steps: A1. Construct the relationship curve between physical variables and biological variables of plain rivers - habitat suitability curve HSC; A2. Use a two-dimensional hydrodynamic model to calculate the output water depth and flow velocity, and calculate the suitability index of each node on the grid through the habitat suitability curve HSC, including the habitat water depth suitability index DHSI of each node and the habitat flow velocity suitability index VHSI of each node, and then draw habitat quality zoning maps of water depth and flow velocity respectively; A3. Calculate the comprehensive index of habitat suitability: Among them, GHSI is a comprehensive indicator of habitat suitability; A4. Based on the comprehensive habitat suitability index GHSI, the sensitive ecological flow of protected species is evaluated.

9. The method for constructing multi-dimensional stepped river ecological flow according to claim 1, characterized in that: In the above S4, the flow rate for river channel bed construction is determined, specifically: the planned regulation flow rate for the main channel of the river channel is used as the flow rate for river channel bed construction.

Images