A method and system for estimating river ecological baseflow based on an improved wetted perimeter method.

Abstract

This invention discloses a method for estimating river ecological baseflow based on an improved wetted perimeter method, comprising: S1. collecting data related to river ecological baseflow; S2. decomposing multi-year river flow by month, and calculating monthly wetted perimeter data of the river channel by combining the decomposed river flow with the hydraulic parameters of the river cross-section; S3. constructing a monthly wetted perimeter-flow curve based on the monthly wetted perimeter data and the decomposed river flow, and determining the points of change on the monthly wetted perimeter-flow curve using the slope 1 method and the maximum curvature method; S4. calculating the ecological flow required by aquatic organisms based on the hydraulic parameters of the river cross-section and the hydraulic parameters of aquatic organisms at different stages; S5. determining whether the obtained ecological baseflow is greater than the calculated ecological flow required by aquatic organisms. If so, the obtained ecological baseflow is the final ecological baseflow value of the river cross-section; if not, the calculated ecological flow required by aquatic organisms is the final ecological baseflow value of the river cross-section.

Description

Technical Field

[0001] This invention relates to the field of ecological baseflow calculation technology, and in particular to a method and system for estimating river ecological baseflow based on an improved wetted perimeter method. Background Technology

[0002] The wetted perimeter method, based on the wetted perimeter-discharge relationship, has wide application value in calculating river ecological baseflow. The wetted perimeter method uses the abrupt change point of the discharge-wetted perimeter curve as the ecological baseflow value for that river segment. Compared to hydrological methods, it fully considers river structure and hydraulic parameters such as water depth, flow velocity, and wetted perimeter, resulting in a more reasonable baseflow value. Traditional wetted perimeter methods construct the discharge-wetted perimeter curve using annual discharge and wetted perimeter data to obtain a single ecological baseflow value for the entire year. However, in northern rivers, the monthly discharge varies significantly throughout the year, making a single baseflow value insufficient to reflect actual river conditions. Furthermore, traditional wetted perimeter methods only consider hydrological and hydraulic factors, thus presenting the following technical problems:

[0003] 1. The baseflow value obtained by the traditional wetted period method is only a single value for the year, and a single baseflow value is difficult to meet the actual situation of rivers in the north.

[0004] 2. The traditional wetted perimeter method is based on various river hydraulic parameters to construct the flow-wetted perimeter relationship. This may result in the ecological base flow ignoring the flow requirements of aquatic organisms at various growth stages, thereby threatening river biodiversity.

[0005] To address the aforementioned technical problems, this invention proposes a method and system for estimating river ecological baseflow based on an improved wetted perimeter method. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing technologies by providing a method and system for estimating river ecological baseflow based on an improved wetted perimeter method. This method takes into account the flow demand of aquatic organisms, resulting in an estimated ecological flow that is more realistic and more conducive to the protection of river aquatic organisms.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A method for estimating river ecological baseflow based on an improved wetted perimeter method includes:

[0009] S1. Collect data related to river ecological baseflow, including the hydraulic parameters and morphology of river cross-sections, the hydraulic parameters of aquatic organisms at different stages, and multi-year river flow.

[0010] S2. Decompose the multi-year river flow into monthly data, and combine the decomposed river flow with the hydraulic parameters and morphology of the river cross-section to calculate the monthly wetted perimeter data of the river channel.

[0011] S3. Based on the monthly wet cycle data of the river channel and the river flow after decomposition by month, construct the monthly wet cycle-flow curve. Use the slope 1 method and the maximum curvature method to determine the change point on the monthly wet cycle-flow curve. This change point is the ecological base flow.

[0012] S4. Calculate the ecological flow required by aquatic organisms based on the hydraulic parameters of the river cross-section and the hydraulic parameters of aquatic organisms at different stages.

[0013] S5. Determine whether the ecological base flow obtained in step S3 is greater than the ecological flow required by aquatic organisms calculated in step S4. If yes, the ecological base flow obtained in step S3 is the final ecological base flow value of the river section; if no, the ecological flow required by aquatic organisms calculated in step S4 is the final ecological base flow value of the river section.

[0014] Furthermore, the hydraulic parameters of the river channel cross-section in step S1 include the water depth, flow velocity, cross-sectional area, wetted perimeter, cross-sectional shape, and hydraulic radius.

[0015] Furthermore, the hydraulic parameters of the aquatic organisms at different stages in step S1 include water depth, flow velocity, wetted perimeter, water surface width, cross-sectional area, water surface area, and water temperature.

[0016] Furthermore, in step S3, the slope 1 method is used to determine the change points on the monthly wet-week flow rate curve, which is expressed as:

[0017]

[0018] Among them, Q S d represents the ecological base flow calculated using the slope 1 method; d represents the river cross-sectional parameters.

[0019] Furthermore, in step S3, the curvature maximum method is used to determine the change points on the monthly wetted cycle-flow curve, which is expressed as:

[0020]

[0021] Among them, Q C d represents the ecological base flow calculated using the maximum curvature method; d represents the river cross-sectional parameters.

[0022] Correspondingly, a river ecological baseflow estimation system based on the improved wetted perimeter method is also provided, including:

[0023] The collection module is used to collect data related to the river's ecological baseflow, including the hydraulic parameters and morphology of the river cross-section, the hydraulic parameters of aquatic organisms at different stages, and the multi-year river flow.

[0024] The first calculation module is used to decompose the multi-year river flow into monthly data, and to calculate the monthly wetted perimeter data of the river channel by combining the decomposed river flow with the hydraulic parameters and morphology of the river channel cross-section.

[0025] The module is used to construct a monthly wet cycle-discharge curve based on the monthly wet cycle data of the river channel and the river flow after decomposition by month. The slope 1 method and the maximum curvature method are used to determine the change point on the monthly wet cycle-discharge curve, and the change point is the ecological base flow.

[0026] The second calculation module is used to calculate the ecological flow required by aquatic organisms based on the hydraulic parameters of the river cross section and the hydraulic parameters of aquatic organisms at different stages.

[0027] The judgment module is used to determine whether the obtained ecological base flow is greater than the calculated ecological flow required by aquatic organisms. If so, the obtained ecological base flow is the final ecological base flow value of the river section; if not, the calculated ecological flow required by aquatic organisms is the final ecological base flow value of the river section.

[0028] Furthermore, the hydraulic parameters of the river cross-section collected in the module include the water depth, flow velocity, cross-sectional area, wetted perimeter, river cross-sectional shape, and hydraulic radius.

[0029] Furthermore, the hydraulic parameters of aquatic organisms in the collection module at different stages include water depth, flow velocity, wetted perimeter, water surface width, cross-sectional area, water surface area, and water temperature.

[0030] Furthermore, the slope 1 method is used in the construction module to determine the change points on the monthly wet-week flow rate curve, which is represented as:

[0031]

[0032] Among them, Q S d represents the ecological base flow calculated using the slope 1 method; d represents the river cross-sectional parameters.

[0033] Furthermore, the curvature maximum method is used in the construction module to determine the change points on the monthly wetted cycle-flow curve, as shown below:

[0034]

[0035] Among them, Q C d represents the ecological base flow calculated using the maximum curvature method; d represents the river cross-sectional parameters.

[0036] Compared with the prior art, the beneficial effects of the present invention are:

[0037] 1. Unlike the traditional wet-period method, which can only estimate a single ecological base flow value throughout the year, this method determines the ecological base flow value for each month by constructing monthly flow-wet-period curves. This method is more in line with the characteristics of annual flow variation in northern rivers, providing a theoretical basis for scientific and precise flow regulation based on seasonal and irrigation needs in river management, and saving water transfer costs.

[0038] 2. Traditional wetted perimeter method only considers river hydraulic factors, while this method takes into account the flow demand of aquatic organisms. The determined ecological base flow value can, to a certain extent, ensure the flow demand of river aquatic organisms at different growth stages, especially the ecological water demand during the breeding season. This is conducive to the growth of aquatic organisms and the protection of river biodiversity, and has important social and ecological benefits. Attached Figure Description

[0039] Figure 1 Here is a flowchart of a river ecological baseflow estimation method based on the improved wetted perimeter method provided in Example 1;

[0040] Figure 2 This is a schematic diagram of the morphological structure of a certain cross section of a river provided in Example 2;

[0041] Figure 3 This is a schematic diagram of the ecological baseflow calculation results provided in Example 2. Detailed Implementation

[0042] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.

[0043] The purpose of this invention is to address the shortcomings of existing technologies by providing a method and system for estimating river ecological baseflow based on an improved wetted perimeter method.

[0044] Example 1

[0045] This embodiment provides a method for estimating river ecological baseflow based on an improved wetted perimeter method, such as... Figure 1 As shown, it includes:

[0046] S1. Data Collection: Collect data related to the river's ecological baseflow, including the hydraulic parameters and morphology of the river cross-section, the hydraulic parameters of aquatic organisms at different stages, and the multi-year river flow.

[0047] S2. Data processing: Decompose the multi-year river flow into monthly data, and combine the decomposed river flow with the hydraulic parameters and morphology of the river cross-section to calculate the monthly wetted perimeter data of the river.

[0048] S3. Monthly construction of flow-wet cycle curve: Based on the monthly wet cycle data of the river channel and the river flow after decomposition by month, a monthly wet cycle-flow curve is constructed. The slope 1 method and the maximum curvature method are used to determine the change point on the monthly wet cycle-flow curve. This change point is the ecological base flow.

[0049] S4. Determine the flow requirements of aquatic organisms: Calculate the ecological flow required by aquatic organisms based on the hydraulic parameters of the river cross-section and the hydraulic parameters of aquatic organisms at different stages.

[0050] S5. Determine the ecological base flow of the river at the current cross-section: Determine whether the ecological base flow obtained in step S3 is greater than the ecological flow required by aquatic organisms calculated in step S4. If yes, the ecological base flow obtained in step S3 is the final ecological base flow value of the river cross-section; if no, the ecological flow required by aquatic organisms calculated in step S4 is the final ecological base flow value of the river cross-section.

[0051] In step S1, data related to the river's ecological base flow are collected, including the hydraulic parameters of the river cross-section, the hydraulic parameters of aquatic organisms at different stages, and the multi-year river flow.

[0052] The hydraulic parameters of a river channel cross-section include:

[0053] Water depth (h): The depth of water in a river channel is one of the key parameters for determining the river's water carrying capacity.

[0054] Flow velocity (v): The speed of water flow. The flow velocity usually varies at different locations on a cross section. The distribution of flow velocity has an important influence on the energy and momentum transfer of water flow.

[0055] Cross-sectional area (A): The area of ​​the river channel through which water flows. It is directly related to the flow rate and is one of the basic parameters for calculating the flow rate.

[0056] Wetted perimeter (X): The perimeter of the river channel section in contact with the water, which is very important for calculating the frictional losses of the water flow and the interaction between the water flow and the riverbed.

[0057] Hydraulic radius (R): This is the effective flow radius of water, which is related to the flow velocity, the cross-sectional area and circumference of the pipe or canal. It is used to calculate hydraulic parameters such as drag coefficient and Reynolds number. The formula for calculating the hydraulic radius varies depending on the geometry of the pipe or canal.

[0058] River channel cross-sectional shape: including rectangular, trapezoidal, semi-circular, etc. Different cross-sectional shapes will affect the distribution and velocity of water flow, and thus affect hydraulic parameters.

[0059] Hydraulic parameters of aquatic organisms at different stages:

[0060] Water depth: Water depth is one of the basic conditions for the survival of aquatic organisms, especially for aquatic animals such as fish. A certain water depth can ensure their activity space and reproductive needs.

[0061] Flow velocity: Flow velocity affects the habitat selection and activity range of aquatic organisms, and different aquatic organisms have different adaptability to flow velocity. Suitable flow velocity helps aquatic organisms with gas exchange and nutrient absorption, while flow velocities that are too fast or too slow may have adverse effects on them.

[0062] Wet perimeter: Wet perimeter refers to the circumference of a river in contact with water and is an important indicator for evaluating habitat quality. The relationship between wet perimeter and flow rate can reflect a river's ability to provide habitat for aquatic organisms.

[0063] Water surface width: Water surface width affects the flow of rivers and the range of aquatic life, and plays an important role in maintaining the health of river ecosystems.

[0064] Cross-sectional area of ​​water flow: The cross-sectional area of ​​water flow affects the distribution of water flow and the habitat of aquatic organisms. It is an important parameter for determining river flow and hydraulic conditions.

[0065] Water surface area: The water surface area is related to the evaporation of water and the photosynthesis of aquatic plants, and has an important impact on the survival and reproduction of aquatic organisms.

[0066] Water temperature: Water temperature is a key factor affecting the growth and reproduction of aquatic organisms. Different species of aquatic organisms have different ranges of adaptation to water temperature, and changes in water temperature will directly affect the physiological activities and distribution of aquatic organisms.

[0067] Rapids, slow currents, shallows, and deep pools: These hydraulic patterns have a significant impact on the habitat selection and behavioral patterns of aquatic organisms. They are the main hydraulic patterns that affect the abundance and distribution of species due to changes in flow.

[0068] These hydraulic parameters collectively determine the hydraulic habitats of aquatic organisms and are crucial for protecting aquatic biodiversity and maintaining the health of river ecosystems. By simulating and calculating these parameters, suitable flow requirements for the survival of aquatic organisms can be determined, providing a scientific basis for the calculation and management of ecological flow.

[0069] Multi-year river flow includes:

[0070] River flow measurements: These data are usually obtained periodically by river observation stations or hydrological stations, reflecting the changes in river flow at different times (such as daily, weekly or monthly).

[0071] Seasonal variations: River flow changes with the seasons; for example, flow may increase during the rainy season and decrease during the dry season. Therefore, organizing flow data by month can help analyze and understand the seasonal variations in river flow.

[0072] Historical flow data: This data may include continuous flow records over many years, used to analyze long-term trends and periodic changes in river flow.

[0073] The relationship between flow rate and wetted perimeter: In the wetted perimeter method, there is a relationship between flow rate data and wetted perimeter (i.e., the circumference of the river in contact with water). By analyzing these data, the ecological base current of a river can be determined, which is the minimum flow rate required to maintain the health of the river ecosystem.

[0074] Organizing the flow data: Organizing this flow data by month is to match the wet cycle data, because the wet cycle also changes with the water level, and this change usually has seasonal characteristics.

[0075] This flow data was used to construct flow-wet period curves, thereby estimating the river's ecological baseflow. This estimation is crucial for the protection and management of river ecosystems because it helps determine the minimum flow required by the river ecosystem under different seasons and water level conditions.

[0076] In step S2, the multi-year river flow is decomposed into monthly data, and the decomposed river flow is combined with the hydraulic parameters and morphology of the river cross-section to calculate the monthly wetted perimeter data of the river channel.

[0077] The collected river flow data over many years is organized by month to ensure that the data for each month is complete. Then, for each month's river flow, the corresponding wetted perimeter data is calculated based on the water level changes in the hydraulic parameters of the river cross-section.

[0078] In step S3, the monthly flow-wet cycle curve is constructed: based on the monthly wet cycle data of the river channel and the river flow after decomposition by month, the monthly wet cycle-flow curve is constructed. The slope 1 method and the maximum curvature method are used to determine the change point on the monthly wet cycle-flow curve. This change point is the ecological base flow.

[0079] For each month's wetted cycle data, a suitable mathematical model (such as a power function or exponential function) is used to fit the monthly wetted cycle-flow curve. During curve fitting, it is necessary to determine the model parameters best suited to the data; this can be achieved using the least squares method or other optimization techniques. For example:

[0080] The slope 1 method is used to determine the points of change on the monthly wetted-period flow curve, which are represented as follows:

[0081]

[0082] Among them, Q S This represents the ecological base flow calculated using the slope 1 method; d represents the river cross-sectional parameters. For actual river cross-sections, the power exponent d is generally less than 0.5.

[0083] The point of change on the monthly wetted cycle-flow curve is determined using the maximum curvature method, and is expressed as follows:

[0084]

[0085] Among them, Q C This represents the ecological baseflow calculated using the maximum curvature method; d represents the river cross-sectional parameters. For actual river cross-sections, the power exponent d is generally less than 0.5.

[0086] In step S4, the ecological flow required by the aquatic organisms is calculated based on the hydraulic parameters of the river cross-section and the hydraulic parameters of the aquatic organisms at different stages.

[0087] The specific method for calculating the ecological flow required by aquatic organisms is as follows:

[0088] Identify key life stages: Identify the key stages in the life cycle of a specific aquatic organism, such as the reproductive period, larval development period, and adult period, each of which may have different flow requirements.

[0089] Collect ecological demand data: Collect ecological flow demand data for specific aquatic organisms at various key stages.

[0090] Analyze hydraulic parameters: Analyze various hydraulic parameters that affect aquatic organisms, such as flow velocity, water depth, wetted perimeter, and hydraulic radius, because these parameters directly affect the quality of aquatic organisms' habitats.

[0091] Establish flow demand models: Using hydraulic parameters and ecological demand data from aquatic organisms, mathematical models are developed to estimate the minimum flow required at different life stages. These models may be based on the physiological needs, behavioral habits, or population dynamics of aquatic organisms.

[0092] Consider seasonal variations: Take into account seasonal flow variations in rivers to ensure that rivers can provide sufficient flow at critical times when aquatic life needs it.

[0093] Integrating the needs of multiple species: If a river contains multiple aquatic organisms, it is necessary to integrate the flow demands of these organisms to ensure the overall health of the river ecosystem.

[0094] Apply ecological flow calculation methods: Use specific ecological flow calculation methods, such as the ecological hydraulic radius method and the multi-objective wetted perimeter method, to determine the ecological flow that meets the needs of all critical materials.

[0095] Verification and Adjustment: Verify the accuracy of the calculation results through field observation or model simulation, and make necessary adjustments based on the actual situation.

[0096] For example, if the calculation results show that a certain minimum flow rate is required during the fish breeding season to ensure spawning and the development of juvenile fish, then this flow rate value will be determined as the ecological base current for that period.

[0097] In this embodiment, the ecological flow required for the fish growth stage is calculated by combining the ecological flow data and river morphology, denoted as Q. f .

[0098] In step S5, it is determined whether the ecological base flow obtained in step S3 is greater than the ecological flow required by aquatic organisms calculated in step S4. If so, the ecological base flow obtained in step S3 is the final ecological base flow value of the river section; if not, the ecological flow required by aquatic organisms calculated in step S4 is the final ecological base flow value of the river section.

[0099] Compare Q S and Q f Size, or comparison Q C and Q f The maximum value is taken as the final ecological baseflow value for that river section.

[0100] The beneficial effects of this embodiment are:

[0101] 1. Unlike the traditional wet-period method, which can only estimate a single ecological base flow value throughout the year, this method determines the ecological base flow value for each month by constructing monthly flow-wet-period curves. This method is more in line with the characteristics of annual flow variation in northern rivers, providing a theoretical basis for scientific and precise flow regulation based on seasonal and irrigation needs in river management, and saving water transfer costs.

[0102] 2. Traditional wetted perimeter method only considers river hydraulic factors, while this method takes into account the flow demand of aquatic organisms. The determined ecological base flow value can, to a certain extent, ensure the flow demand of river aquatic organisms at different growth stages, especially the ecological water demand during the breeding season. This is conducive to the growth of aquatic organisms and the protection of river biodiversity, and has important social and ecological benefits.

[0103] Accordingly, this embodiment also provides a river ecological baseflow estimation system based on the improved wetted perimeter method, including:

[0104] The collection module is used to collect data related to the river's ecological baseflow, including the hydraulic parameters and morphology of the river cross-section, the hydraulic parameters of aquatic organisms at different stages, and the multi-year river flow.

[0105] The first calculation module is used to decompose the multi-year river flow into monthly data, and to calculate the monthly wetted perimeter data of the river channel by combining the decomposed river flow with the hydraulic parameters and morphology of the river channel cross-section.

[0106] The module is used to construct a monthly wet cycle-discharge curve based on the monthly wet cycle data of the river channel and the river flow after decomposition by month. The slope 1 method and the maximum curvature method are used to determine the change point on the monthly wet cycle-discharge curve, and the change point is the ecological base flow.

[0107] The second calculation module is used to calculate the ecological flow required by aquatic organisms based on the hydraulic parameters of the river cross section and the hydraulic parameters of aquatic organisms at different stages.

[0108] The judgment module is used to determine whether the obtained ecological base flow is greater than the calculated ecological flow required by aquatic organisms. If so, the obtained ecological base flow is the final ecological base flow value of the river section; if not, the calculated ecological flow required by aquatic organisms is the final ecological base flow value of the river section.

[0109] Furthermore, the hydraulic parameters of the river cross-section collected in the module include the water depth, flow velocity, cross-sectional area, wetted perimeter, river cross-sectional shape, and hydraulic radius.

[0110] Furthermore, the hydraulic parameters of aquatic organisms in the collection module at different stages include water depth, flow velocity, wetted perimeter, water surface width, cross-sectional area, water surface area, and water temperature.

[0111] Furthermore, the slope 1 method is used in the construction module to determine the change points on the monthly wet-week flow rate curve, which is represented as:

[0112]

[0113] Among them, Q S d represents the ecological base flow calculated using the slope 1 method; d represents the river cross-sectional parameters.

[0114] Furthermore, the curvature maximum method is used in the construction module to determine the change points on the monthly wetted cycle-flow curve, as shown below:

[0115]

[0116] Among them, Q C d represents the ecological base flow calculated using the maximum curvature method; d represents the river cross-sectional parameters.

[0117] Example 2

[0118] The river ecological baseflow estimation method based on the improved wetted perimeter method provided in this embodiment differs from that in Embodiment 1 in that:

[0119] like Figure 2 The image shows the morphological structure of a cross-section of a river. Figure 2 Based on the structural diagram and collected water level data, wetted perimeter data under a specific flow rate is calculated. Monthly flow-wetted perimeter curves are constructed using the monthly wetted perimeter flow data, and the points with the largest slope and curvature on these curves are calculated. Combined with the water level data for this section, the river channel shape approximates a triangle, making a power function suitable for fitting the relationship. For computational convenience, the wetted perimeter-flow data is dimensionless, as shown in the following formula:

[0120]

[0121] Where q and p are the relative ecological base current and relative wetted perimeter, respectively. m Select the maximum flow rate, P m The maximum wetted perimeter is selected, where d is a parameter related to the cross-sectional shape. For actual river cross-sections, the power exponent d is generally less than 0.5. Q S Q is the ecological base current calculated using the slope method. C For the ecological base current calculated using the curvature method, m 3 / s.

[0122] Based on collected aquatic organism data (mainly fish, including data on flow velocity and water depth during fish spawning) and river morphology, the ecological flow Q required for fish growth stages is calculated. f and Q f With Q S Q C A comparison was made to determine the appropriate ecological base current. Fish growth flow primarily considered the flow during the breeding season, specifically March-April for the Fen River's endemic fish species, *Leuciscus vannamei*, and May-June for the four major freshwater fish species. Figure 3 As can be seen, Q is determined by the slope method. S The value in each month is greater than Q. C Except for March, the rest of Q S The values ​​are all within the suitable flow range for fish growth, which can meet the flow requirements during the fish breeding season. In March, Q... S The value is greater than the maximum flow rate required for the reproduction of *Leuciscus variabilis*, and needs to be adjusted. Therefore, the maximum flow rate Q during the fish breeding season is taken. fmax The ecological base flow for the month is 4.41 m³ / s. In summary, the annual ecological base flow value is determined to be 0.49 m³ / s. 3 / s, 0.77m 3 / s, 4.41m 3 / s, 0.76m 3 / s, 1.16m 3 / s, 1.16m 3 / s, 1.17m3 / s, 1.68m 3 / s, 0.96m 3 / s, 1.04m 3 / s, 0.98m 3 / s, 0.64m 3 / s.

[0123] By improving the traditional wet cycle method, we have obtained the monthly ecological base flow, providing a theoretical basis for river management throughout the year. On the other hand, the ecological base flow determined based on the flow demand of river aquatic organisms meets the needs of local river aquatic organisms at different growth stages, which is conducive to the reproduction and growth of aquatic organisms and further protects river biodiversity.

[0124] Example 3

[0125] The river ecological baseflow estimation method based on the improved wetted perimeter method provided in this embodiment differs from that in Embodiment 1 in that:

[0126] To improve the accuracy of ecological baseflow estimation, this embodiment also incorporates environmental gradient and seasonal variation factors, specifically:

[0127] In the data collection in step S1, in addition to the hydraulic parameters of the river cross section, the hydraulic parameters of aquatic organisms at different stages, and the multi-year river flow, this embodiment also needs to collect data on environmental gradient and seasonal changes.

[0128] 1. Improve the Tennant method by introducing environmental gradient and seasonal coefficient.

[0129] Environmental gradient: refers to the natural slope of a river and the impact of human activities on the river's slope. This embodiment also considers the impact of the natural slope of the river and human activities on the river's slope, therefore, environmental gradient is introduced as a correction factor to adjust the calculation of ecological baseflow, expressed as:

[0130] Q eco =Q base ×(1+α×S)

[0131] Among them, Q eco Indicates the adjusted ecological base flow; Q base This represents the basic ecological base current calculated based on the Tennant method; α represents the correction coefficient used to adjust for the impact of environmental gradient; S represents the environmental gradient.

[0132] Seasonal coefficient: Based on the changing needs of aquatic organisms and river flow in different seasons, a seasonal coefficient is introduced to adjust the ecological baseflow. For example, increasing the baseflow during the fish breeding season to meet breeding needs is expressed as:

[0133] Q eco =Q base×C season

[0134] Among them, C season The seasonal coefficient for the identifier is adjusted according to different seasons.

[0135] In the data processing of step S2, when decomposing the multi-year river flow by month, it is necessary to consider seasonal changes and use a seasonal coefficient to adjust the flow data.

[0136] Flow adjustment specifically involves correcting the flow rates of rivers that have received water replenishment and those that have not, taking into account the impact of human activities on river flow. Historical flow data is used to analyze flow changes before and after human activities, and adjustments are made to the ecological base flow.

[0137] In step S3, when constructing the monthly flow-wet period curve, the improved Tennant method is used to calculate the ecological base flow for each month, taking into account the effects of environmental gradient and seasonal coefficient.

[0138] The improved Tennant method is expressed as:

[0139]

[0140] Among them, W eco M represents the ecological base flow of the river channel. i N represents the average annual flow in the i-th month of the year; i This represents the percentage of ecological base flow corresponding to month i.

[0141] Based on the improved formula, the monthly flow data is calculated to obtain the monthly ecological base flow value. The calculation results are then adjusted according to the actual needs of aquatic organisms and the river conditions to ensure that the ecological base flow value can meet the needs of aquatic organisms while also taking into account the impact of human activities.

[0142] In step S4, when determining the flow demand of aquatic organisms, the impact of seasonal changes on the demand of aquatic organisms is considered when calculating the ecological flow required by aquatic organisms, and the demand for ecological flow is adjusted using a seasonal coefficient.

[0143] Monthly ecological flow calculation: The ecological flow for each month is calculated based on the needs of aquatic organisms and seasonal coefficients. For example, during the fish breeding season, the flow may need to be increased to meet breeding needs; during the dry season, the flow may need to be reduced to protect the habitats of aquatic organisms.

[0144] In step S5, when determining the current cross-section of the river's ecological base flow, the ecological base flow value is compared with the ecological flow required by aquatic organisms after considering the environmental gradient and seasonal coefficient, and the larger value is taken as the final ecological base flow value.

[0145] The above methods can more comprehensively consider environmental gradient and seasonal variation factors, thereby improving the accuracy and applicability of ecological baseflow estimation.

[0146] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A method for estimating river ecological baseflow based on an improved wetted perimeter method, characterized in that, include: S1. Collect data related to river ecological baseflow, including the hydraulic parameters and morphology of river cross-sections, the hydraulic parameters of aquatic organisms at different stages, and multi-year river flow. S2. Decompose the multi-year river flow into monthly data, and combine the decomposed river flow with the hydraulic parameters and morphology of the river cross-section to calculate the monthly wetted perimeter data of the river channel. S3. Based on the monthly wet cycle data of the river channel and the river flow after decomposition by month, construct the monthly wet cycle-flow curve. Use the slope 1 method and the maximum curvature method to determine the change point on the monthly wet cycle-flow curve. This change point is the ecological base flow. S4. Calculate the ecological flow required by aquatic organisms based on the hydraulic parameters of the river cross-section and the hydraulic parameters of aquatic organisms at different stages. The specific method for calculating the ecological flow required by aquatic organisms is as follows: Identifying key life stages: Identifying the key stages in the life cycle of a specific aquatic organism; Collect ecological demand data: Collect ecological flow demand data for specific aquatic organisms at various key stages; Analyze hydraulic parameters: Analyze various hydraulic parameters that affect aquatic organisms; Establish a flow demand model: Using hydraulic parameters and ecological demand data of aquatic organisms, establish a mathematical model to estimate the minimum flow required for different life stages; Consider seasonal variations: take into account seasonal variations in river flow; Integrating the needs of multiple species: Integrating the flow needs of various organisms; Applying ecological flow calculation methods: Using ecological flow calculation methods to determine the ecological flow required to meet the needs of all critical materials; S5. Determine whether the ecological base flow obtained in step S3 is greater than the ecological flow required by aquatic organisms calculated in step S4. If yes, the ecological base flow obtained in step S3 is the final ecological base flow value of the river section; if no, the ecological flow required by aquatic organisms calculated in step S4 is the final ecological base flow value of the river section.

2. The method for estimating river ecological baseflow based on the improved wetted perimeter method according to claim 1, characterized in that, The hydraulic parameters of the river cross-section in step S1 include the water depth, flow velocity, cross-sectional area, wetted perimeter, river cross-sectional shape, and hydraulic radius.

3. The method for estimating river ecological baseflow based on the improved wetted perimeter method according to claim 1, characterized in that, In step S1, the hydraulic parameters of aquatic organisms at different stages include water depth, flow velocity, wetted perimeter, water surface width, cross-sectional area, water surface area, and water temperature.

4. The method for estimating river ecological baseflow based on the improved wetted perimeter method according to claim 1, characterized in that, In step S3, the slope 1 method is used to determine the change points on the monthly wetted-weekly flow rate curve, which is represented as follows: Among them, Q S d represents the ecological base flow calculated using the slope 1 method; d represents the river cross-sectional parameters.

5. The method for estimating river ecological baseflow based on the improved wetted perimeter method according to claim 1, characterized in that, In step S3, the curvature maximum method is used to determine the change points on the monthly wetted cycle-flow curve, which are represented as follows: Among them, Q C d represents the ecological base flow calculated using the maximum curvature method; d represents the river cross-sectional parameters.

6. A river ecological baseflow estimation system based on an improved wetted perimeter method, characterized in that, include: The collection module is used to collect data related to the river's ecological baseflow, including the hydraulic parameters and morphology of the river cross-section, the hydraulic parameters of aquatic organisms at different stages, and the multi-year river flow. The first calculation module is used to decompose the multi-year river flow into monthly data, and to calculate the monthly wetted perimeter data of the river channel by combining the decomposed river flow with the hydraulic parameters and morphology of the river channel cross-section. The module is used to construct a monthly wet cycle-discharge curve based on the monthly wet cycle data of the river channel and the river flow after decomposition by month. The slope 1 method and the maximum curvature method are used to determine the change point on the monthly wet cycle-discharge curve, and the change point is the ecological base flow. The second calculation module is used to calculate the ecological flow required by aquatic organisms based on the hydraulic parameters of the river cross section and the hydraulic parameters of aquatic organisms at different stages. The specific method for calculating the ecological flow required by aquatic organisms is as follows: Identifying key life stages: Identifying the key stages in the life cycle of a specific aquatic organism; Collect ecological demand data: Collect ecological flow demand data for specific aquatic organisms at various key stages; Analyze hydraulic parameters: Analyze various hydraulic parameters that affect aquatic organisms; Establish a flow demand model: Using hydraulic parameters and ecological demand data of aquatic organisms, establish a mathematical model to estimate the minimum flow required for different life stages; Consider seasonal variations: take into account seasonal variations in river flow; Integrating the needs of multiple species: Integrating the flow needs of various organisms; Applying ecological flow calculation methods: Using ecological flow calculation methods to determine the ecological flow required to meet the needs of all critical materials; The judgment module is used to determine whether the obtained ecological base flow is greater than the calculated ecological flow required by aquatic organisms. If so, the obtained ecological base flow is the final ecological base flow value of the river section; if not, the calculated ecological flow required by aquatic organisms is the final ecological base flow value of the river section.

7. A river ecological baseflow estimation system based on the improved wetted perimeter method according to claim 6, characterized in that, The hydraulic parameters of the river cross-section collected in the module include water depth, flow velocity, cross-sectional area, wetted perimeter, river cross-sectional shape, and hydraulic radius.

8. A river ecological baseflow estimation system based on the improved wetted perimeter method according to claim 6, characterized in that, The hydraulic parameters of aquatic organisms in the collection module at different stages include water depth, flow velocity, wetted perimeter, water surface width, cross-sectional area, water surface area, and water temperature.

9. A river ecological baseflow estimation system based on the improved wetted perimeter method according to claim 6, characterized in that, The construction module uses the slope 1 method to determine the change points on the monthly wetted-weekly flow rate curve, represented as follows: Among them, Q S d represents the ecological base flow calculated using the slope 1 method; d represents the river cross-sectional parameters.

10. A river ecological baseflow estimation system based on the improved wetted perimeter method according to claim 6, characterized in that, The construction module uses the maximum curvature method to determine the change points on the monthly wetted cycle-flow curve, represented as follows: Among them, Q C d represents the ecological base flow calculated using the maximum curvature method; d represents the river cross-sectional parameters.

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