Method for calculating ecological base flow in dry season in arid and semi-arid regions

Abstract

The application discloses a kind of dry and semi-arid region ecological base flow in dry season calculation method, belong to hydrology water resources and ecological environment protection technical field.The present application aims at solving the problems of single dimension one-sidedness, strong subjectivity of result, difficult to balance ecological demand and human water conflict existing in prior art.The method obtains the basic data of the target river channel control section;Accordingly, the first calculation strategy is executed to generate the basic ecological base flow, and the second calculation strategy is executed to form the recommended ecological base flow interval;If the basic ecological base flow falls into the recommended ecological base flow interval, it is directly determined as the ecological base flow in dry season, otherwise, a uniform candidate flow set within the closed effective flow interval is constructed, the short board constraint index is calculated dimension by dimension, and the ecological base flow in dry season is determined by progressive screening according to the multi-level priority of ecological priority.The present application takes into account the hydrological physical constraint and ecological demand, avoids subjective weighting, and realizes the balance of ecological safety and efficient use of water resources.

Description

Technical Field

[0001] This invention relates to the field of hydrology, water resources and ecological environment protection technology, specifically to a method for calculating the ecological base flow during the dry season in arid and semi-arid regions. Background Technology

[0002] Arid and semi-arid regions are the most ecologically fragile areas in my country, characterized by extremely low river runoff during the dry season, large interannual variability, and frequent seasonal flow interruptions. The scientific determination of the ecological baseflow during the dry season is a core foundation for maintaining the health of river ecosystems and ensuring the sustainable use of water resources in the basin. Existing methods for calculating ecological baseflow are mainly divided into four categories: hydrological methods, hydraulic methods, habitat simulation methods, and eco-hydrological response methods. Among these, the Tennant method and the wetted perimeter method have been applied to some extent in arid and semi-arid regions, but they generally suffer from problems such as being one-dimensional and biased, having highly subjective results, and failing to simultaneously consider the stability of river channel morphology and the needs of the ecosystem. For example, the invention patent application with patent publication number CN121901561A determines the protection threshold of the beach by identifying the abrupt change point of the water level-wet perimeter relationship curve, and infers the ecological base flow by combining the water depth requirements of aquatic organisms. It also supplements the existing technology for calculating flow during the freezing period. However, it only considers the river morphology and water depth constraints of a single organism, and does not include core ecological indicators of arid and semi-arid areas such as groundwater depth and riparian vegetation. It also does not establish a coupling verification mechanism between hydrological statistical laws and ecological needs, and cannot effectively balance ecological security and human production and living water needs.

[0003] Furthermore, existing technologies have significant shortcomings in their decision-making mechanisms under conflict scenarios. Most rely on simple weighted summation or single threshold judgment, with weight assignment depending on expert experience and lacking objective and unified standards. Some methods construct candidate flow sets that suffer from uneven distribution and insufficient coverage of key sensitive areas, resulting in poor representativeness and low robustness of the screening results. Simultaneously, existing technologies fail to fully reflect the principle of "absolute priority of ecological needs" in arid and semi-arid regions. When hydrophysical constraints conflict with ecological needs, it is difficult to scientifically determine the optimal ecological baseflow that balances ecological baselines and water resource carrying capacity, thus failing to meet the practical needs of refined watershed water resource management and ecological protection. Summary of the Invention

[0004] The purpose of this invention is to provide a method for calculating the ecological base flow during the dry season in arid and semi-arid regions, so as to at least solve the problems of existing technologies, such as being one-dimensional and one-sided, having strong subjectivity in the results, and being difficult to balance ecological security and human water demand.

[0005] To achieve the above objectives, this invention provides a method for calculating the ecological base current during the dry season in arid and semi-arid regions, comprising:

[0006] S1. Obtain basic data of the target river channel control section, including long-term dry season daily runoff data, river channel cross-section data, ecological monitoring data, and watershed human activity data;

[0007] S2. Based on long-sequence dry season daily runoff data and river cross-section data, execute the first calculation strategy to generate basic ecological base flow;

[0008] S3. Based on ecological monitoring data, execute the second calculation strategy to form a recommended ecological base flow interval;

[0009] S4. Determine whether the basic ecological base flow falls within the recommended ecological base flow range. If the basic ecological base flow falls within the recommended ecological base flow range, then determine that the basic ecological base flow is the dry season ecological base flow; otherwise, proceed to S5.

[0010] S5. Construct a candidate flow set, calculate the bottleneck constraint indicators in different dimensions, and screen them step by step according to the multi-level priority of ecological priority to determine the dry season ecological base flow.

[0011] Preferably, the long-sequence dry season daily runoff data is the daily runoff from November to April of the following year for at least 15 consecutive years. The ecological monitoring data includes groundwater depth data, riparian vegetation coverage data, and dissolved oxygen data. The watershed human activity data includes watershed water resource development and utilization rate data and ecological risk level data.

[0012] Preferably, the river cross-section data is a complete set of measured data on the cross-section topography, geometry, hydraulic characteristics and bottom conditions obtained through field surveys or long-term monitoring by hydrological stations, with the river control section perpendicular to the water flow direction. This includes cross-section topographic coordinate data, cross-section geometric parameters, water level-hydraulic parameter correspondence, and cross-section bottom data.

[0013] Preferably, the first calculation strategy is:

[0014] Based on long-series daily runoff data during the dry season, a modified Tennant method is used to calculate hydrological statistical thresholds. The calculation process of the modified Tennant method is as follows:

[0015] Based on the daily runoff from November to April of the following year for at least 15 consecutive years, using the formula... Calculate the average dry season flow over many years In the formula, n represents the number of years spanned by the measurement of daily runoff data during the long dry season. Let be the average daily runoff during the dry season of year i, i.e., the average dry season runoff.

[0016] Calculate the interannual variation coefficient of dry season runoff The coefficient of variation of dry season runoff is used to characterize the interannual fluctuation of dry season runoff. The formula for calculating the interannual variation coefficient of dry season runoff is as follows: Based on this, according to the interannual variation coefficient of dry season runoff Calculate the interannual correction factor To correct the shortcoming of the original Tennant method, which did not consider the large interannual variability of dry season runoff in arid and semi-arid regions, the formula for calculating the interannual correction coefficient is as follows: ;

[0017] Based on the average dry season flow over many years and interannual correction factor Calculate hydrological statistical thresholds The formula for calculating the hydrological statistical threshold is:

[0018] ;

[0019] Among them, 20% is the generally accepted minimum flow percentage standard for maintaining basic hydrological connectivity of rivers in arid and semi-arid regions;

[0020] Based on cross-sectional data of the river channel, the wetted perimeter method is used to calculate the river channel morphology threshold. The calculation process of the wetted perimeter method is as follows:

[0021] Based on the cross-sectional data of the target river channel control section, plot the relationship curves between wetted perimeter P and corresponding flow rate Q under different flow rates. ;

[0022] Determining the relationship curve using the maximum curvature method The inflection point of the curve, calculate the relationship curve The curvature K at each point is given by the formula: In the formula, The first derivative of the wetted perimeter-flow rate curve. The second derivative of the wetted perimeter-discharge relationship curve is the discharge corresponding to the maximum curvature, which is the channel morphology threshold.

[0023] Determine the width-to-depth ratio of the target river channel at the control section. Where B is the width of the river channel and h is the average water depth at the corresponding flow rate, when the width-to-depth ratio of the river channel is... At that time, the correction factor for wide and shallow river channels was used. Threshold for original river channel morphology After making corrections, the final river channel morphology threshold is obtained. The corrected calculation formula is as follows: Correction coefficient for wide and shallow river channels The value range is 1.05-1.15;

[0024] When the width and depth of the river channel are equal In this case, the original channel morphology threshold is directly used as the final channel morphology threshold. ;

[0025] The maximum value between the hydrological statistical threshold and the river channel morphology threshold is taken as the basic ecological baseflow. It is used to meet the long-term hydrological statistical stability and channel physical morphology stability of rivers in arid and semi-arid regions.

[0026] Preferably, the second calculation strategy is:

[0027] Based on ecological monitoring data, the lower limit of the ecological threshold is calculated using the eco-hydrological response method. The calculation process of the eco-hydrological response method is as follows:

[0028] Based on ecological monitoring data at the target river control section, including groundwater depth data, riparian vegetation coverage data, and dissolved oxygen data for at least 5 consecutive years, time-matching was performed with the flow rate for the corresponding period to establish quantitative response relationships between groundwater depth, riparian vegetation coverage, and dissolved oxygen and flow rate. Specifically, the quantitative response relationship between groundwater depth and flow rate was obtained by fitting a linear regression model, the quantitative response relationship between riparian vegetation coverage and flow rate was obtained by fitting a logarithmic regression model, and the quantitative response relationship between dissolved oxygen and flow rate was obtained by fitting a power function regression model.

[0029] The quantitative response expression between groundwater depth index and flow rate is as follows:

[0030] ;

[0031] Where D is the average groundwater depth within a 1km radius of the target river control section. This represents the average flow rate during the dry season. , These are the regression coefficients;

[0032] The quantitative response expression between riparian vegetation coverage and flow rate is as follows:

[0033] ;

[0034] Where C represents the riparian vegetation coverage within a 1km radius of the target river control section. , These are the regression coefficients;

[0035] The quantitative response expression between dissolved oxygen in water and flow rate is as follows:

[0036] ;

[0037] Wherein, DO represents the dissolved oxygen concentration in the water at the target river control section. , , These are the regression coefficients;

[0038] Determine the health threshold values ​​for groundwater depth, riparian vegetation coverage, and dissolved oxygen in water bodies. The maximum water absorption depth of the root system of dominant species in the riparian zone of arid and semi-arid regions is taken as the health threshold value of the riparian vegetation coverage index. The minimum coverage rate required to maintain the stability of the riparian ecosystem and the healthy critical value of dissolved oxygen in the water body are taken as the minimum coverage rate. Take the minimum concentration required to maintain the basic survival of aquatic organisms;

[0039] The critical flow rates corresponding to each indicator are obtained by back-calculating the quantitative response relationship and the health threshold. , and , The critical flow rate for groundwater depth index. The critical flow rate is the indicator of riparian vegetation coverage. The critical flow rate for dissolved oxygen in water bodies;

[0040] The maximum value among the three critical flow values ​​mentioned above is taken as the lower limit of the ecological threshold. It is the minimum ecological requirement to meet the needs of groundwater recharge, riparian vegetation survival, and basic water self-purification capacity. It is the survival red line for river ecosystems in arid and semi-arid regions.

[0041] Based on cross-sectional data of the river channel and the habitat suitability curve of the target species, the upper limit of habitat suitability was calculated using the CASiMiR model (computer-aided simulation model of in-channel flow and riparian habitat). The calculation process of the CASiMiR model is as follows:

[0042] The cross-sectional data of the target river control section and the habitat suitability curves of the target species (habitat suitability curves of the target native fish, including water depth suitability curves, flow velocity suitability curves, and substrate suitability curves, drawn by humans) are input into the CASiMiR model. The CASiMiR model divides the river cross-section into several computational units and calculates the comprehensive habitat suitability index for each computational unit. The formula is: In the formula, Let i be the water depth suitability index for the i-th calculation unit. Let i be the flow velocity suitability index for the i-th computational unit. , where is the substrate suitability index for the i-th calculation unit, and its value ranges from 0 to 1;

[0043] Based on this, the weighted usable area (WUA) of the entire river channel cross-section is calculated using the following formula: In the formula, m is the total number of calculation units. Let be the area of ​​the i-th calculation unit;

[0044] Plotting Weighted Available Area (WUA) and Dry Season Average Flow The relationship curve shows that when WUA reaches 70% of its maximum value, the average dry season flow corresponds to the upper limit of habitat suitability. Once this flow rate is exceeded, habitat suitability will no longer improve significantly, and instead it will lead to a waste of scarce water resources in arid and semi-arid areas.

[0045] Based on this, a recommended ecological base current range is formed. This is used to cover a reasonable flow range from basic ecosystem survival to good habitat status.

[0046] Preferably, the candidate traffic set is constructed as follows:

[0047] Using the lower limit of the ecological threshold Lower bound of the interval upper limit of suitable habitat With basic ecological base flow The larger value in the interval is the upper bound. To form a closed effective flow range ;

[0048] Within the closed effective flow range, based on the range length Select flow step size Within the closed effective flow range Internal flow step size Uniformly select basic candidate flow points, among which The range of values ​​is: At that time, take , At that time, take , At that time, take The number of basic candidate flow points ;

[0049] All basic candidate flow points, as well as the candidate flows corresponding to the lower and upper bounds of the intervals, are aggregated and merged. Duplicate candidate flows are removed and sorted in ascending order to form a candidate flow set.

[0050] Preferably, the rule for multi-level priority selection based on ecological priority is as follows:

[0051] Following the principle of absolute priority for ecological needs, all candidate flows in the candidate flow set are progressively screened in order of priority from highest to lowest: ecological response dimension, habitat suitability dimension, hydrological statistics dimension, river morphology dimension, and human activities and ecological risks dimension.

[0052] Each level of screening retains candidate flows whose corresponding dimension's shortcoming score meets the preset threshold. If one candidate flow remains after the first four levels of screening, that candidate flow is taken as the dry season ecological base flow; otherwise, the candidate flow with the highest shortcoming score in the human activity and ecological risk dimensions is selected as the dry season ecological base flow.

[0053] Preferably, the multi-dimensional assessment of the bottleneck constraint indicators and the rule for hierarchical selection based on ecological priority are as follows:

[0054] The score for each dimension's shortcomings is defined as a normalized constraint satisfaction score, with a value range of 0-1. A higher score for a dimension's shortcomings indicates a better degree of satisfaction of the corresponding dimension's ecological needs or physical constraints.

[0055] Each candidate traffic in the candidate traffic set is calculated sequentially. The scores for shortcomings in the corresponding dimensions of ecological response, habitat suitability, hydrological statistics, river morphology, and human activities and ecological risks are then used to progressively screen the data according to the principle of ecological priority.

[0056] (1) Calculate the score of the shortcomings in the ecological response dimension. Based on the lower limit of the ecological threshold The calculation formula is as follows: The preset threshold for this dimension is 0.95, and it is used for filtering and retention. Candidate traffic;

[0057] (2) Calculate the score of the shortcomings in the habitat suitability dimension. Based on the upper limit of suitable habitat The calculation formula is as follows: The preset threshold for this dimension is 0.70, and the filter retains... Candidate traffic;

[0058] (3) Calculate the score for shortcomings in hydrological statistics dimension Based on hydrological statistical thresholds The calculation formula is as follows: The preset threshold for this dimension is 0.80, and the filter retains... Candidate traffic;

[0059] (4) Calculate the score of the shortcomings in the river channel morphology dimension. Based on river channel morphology threshold The calculation formula is as follows: The preset threshold for this dimension is 0.80, and the filter retains... Candidate traffic;

[0060] (5) Calculate the score of the shortcomings in the dimension of human activities and ecological risks. Based on the watershed water resources development and utilization rate Average flow during the dry season over many years Ecological threshold lower limit and habitat suitability limit The calculation is as follows:

[0061] Calculate the water displacement pressure score : ,like If the calculation result is less than 0, take 0; if it is greater than 1, take 1.

[0062] Calculate the ecological risk resilience score : ,like If the calculation result is less than 0, take 0; if the result is greater than 1, take 1.

[0063] The minimum value of the water extraction pressure score and the ecological risk resistance score is used as the shortcoming score of the human activities and ecological risk dimension.

[0064] The progressive screening is carried out in the order of priority from (1) to (4) above. Each screening level retains only the candidate flow with a shortcoming score of not less than the corresponding preset threshold. If only one candidate flow remains after four screening levels, the candidate flow is directly determined as the dry season ecological base flow. If two or more candidate flows remain, the candidate flow with the highest shortcoming score in the human activity and ecological risk dimension is selected as the final dry season ecological base flow.

[0065] If multiple candidate flows have the same score for the human activity and ecological risk dimension shortcomings and are at the highest value, then the candidate flow with the smallest flow is selected as the final dry season ecological base flow.

[0066] The beneficial effects achieved by the present invention using the above technical solution are as follows:

[0067] 1. This invention integrates five core constraints: hydrological statistics, river morphology, ecological response, habitat suitability, human activities, and ecological risks. The ecological response dimension specifically incorporates key indicators for arid and semi-arid regions, such as groundwater depth and riparian vegetation coverage. At the same time, it establishes a unified normalized score system for shortcomings and proposes a two-way game model for water use pressure and ecological risk resistance, achieving differentiated and objective calculation of the constraint intensity of different candidate flows, with no subjective links throughout the process.

[0068] 2. This invention follows the principle of ecological priority and constructs a rigid progressive screening process. The first four levels successively ensure the ecological survival red line, basic habitat requirements, hydrological statistical stability and river morphology safety, thereby preventing the ecological bottom line from being breached. The final level, under the premise of meeting all preconditions, selects the optimal solution through the human activity dimension shortcoming score, so as to achieve efficient utilization of scarce water resources in arid and semi-arid areas.

[0069] 3. This invention adopts a three-level architecture of basic value generation, interval verification, and progressive screening. In normal scenarios, the result can be directly determined as long as the basic value falls into the recommended interval, which greatly improves the computational efficiency. In conflict scenarios, a closed effective flow interval is constructed, and the sampling step size is dynamically adjusted according to the interval length. Sampling is encrypted in key sensitive areas, which not only avoids the omission of the optimal solution, but also controls the amount of computation, thereby improving the robustness and engineering practicality of the results. Attached Figure Description

[0070] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings:

[0071] Figure 1 This is a flowchart illustrating the steps of the method for calculating the dry season ecological base flow in arid and semi-arid regions according to the present invention. Detailed Implementation

[0072] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0073] For examples, see Figure 1 This embodiment provides a method for calculating the dry season ecological base flow in arid and semi-arid regions. The study focuses on a control section of an inland river tributary in Northwest my country. This section is located in the transition zone between arid and semi-arid regions. The proportion of agricultural irrigation water use in the basin is high, the water resource development and utilization rate is relatively high, the risk of river flow interruption during the dry season is prominent, and the ecosystem is fragile.

[0074] S1. Obtain basic data of the target river channel control section.

[0075] Daily runoff data from November to April of the following year were collected for this control section for 15 consecutive years from 2008 to 2022. The average dry season flow over many years was obtained through statistical calculation. Data on the river's cross-section was obtained through on-site surveys, and the width-to-depth ratio under typical flow conditions was measured. It is a wide and shallow river channel; ecological monitoring data were collected for five consecutive years from 2018 to 2022, including groundwater depth data, riparian vegetation coverage data, and dissolved oxygen data within a 1km radius of the cross-section; data on human activities in the basin were also obtained, including the basin's water resource development and utilization rate. The ecological risk level is medium.

[0076] S2. Execute the first computational strategy to generate the basic ecological basestream.

[0077] (1) Calculate hydrological statistical thresholds using the modified Tennant method: First, calculate the interannual variation coefficient of dry season runoff. Substituting into the formula, we get: Calculate the interannual correction factor based on the interannual variation coefficient of dry season runoff. : Finally, the hydrological statistical threshold is calculated. : =0.574 .

[0078] (2) Calculate the channel morphology threshold using the wetted perimeter method: Plot the wetted perimeter-discharge relationship curve based on the cross-sectional data of the channel. The original channel morphology threshold corresponding to the curve inflection point was determined using the maximum curvature method. Due to the width-to-depth ratio of this cross-section Correction coefficient for wide and shallow river channels The threshold for the original river channel morphology is corrected: .

[0079] (3) Determine the basic ecological base flow: Take the maximum value between the hydrological statistical threshold and the channel morphology threshold as the basic ecological base flow: .

[0080] S3. Execute the second calculation strategy to form the recommended ecological baseflow interval.

[0081] (1) Calculate the lower limit of the ecological threshold using the eco-hydrological response method. By temporally matching ecological monitoring data with the average dry season flow for the corresponding period, quantitative response relationships between each indicator and flow were established:

[0082] Groundwater depth index: Among them, the health threshold (Maximum root water absorption depth of Tamarix chinensis, a dominant species in riparian zones of arid and semi-arid regions), and the critical flow rate is derived by reverse calculation. ;

[0083] Riverbank vegetation coverage index: Among them, the health threshold (Minimum cover rate to maintain riparian ecosystem stability) is used to deduce the critical flow rate. ;

[0084] Dissolved oxygen index in water bodies: Among them, the health threshold (The minimum concentration required to maintain the basic survival of native fish species) is used to deduce the critical flow rate. ;

[0085] The maximum value among the three critical flow values ​​is taken as the lower limit of the ecological threshold: ;

[0086] (2) The upper limit of habitat suitability was calculated using the CASiMiR model. The cross-sectional data of the river channel and the water depth, flow velocity, and substrate suitability curves of the target native fish species were input into the CASiMiR model to calculate the weighted usable area (WUA) under different flow rates. The relationship curve between WUA and the average dry season flow rate was plotted. When WUA reaches 70% of its maximum value, the corresponding flow rate is... That is, the upper limit of suitable habitat. .

[0087] (3) Determine the recommended ecological base flow interval

[0088] The final recommended ecological base flow range is as follows: .

[0089] S4. Determine whether the basic ecological base flow falls within the recommended range.

[0090] Basic ecological base flow With [1.65, 2.80] The comparison results show that 0.574 < 1.65, indicating that the basic ecological base flow does not fall within the recommended ecological base flow range. Therefore, step S5 is executed.

[0091] S5. Construct a candidate flow set and screen it step by step to determine the dry season ecological baseflow.

[0092] (1) Construct a candidate traffic set

[0093] Using the lower limit of the ecological threshold Lower bound of the interval The upper bound of the interval is the larger of the upper limit of habitat suitability and the basic ecological base flow. This forms a closed effective flow range [1.65, 2.80]. Interval length .because Select flow step size Calculate the number of basic candidate flow points The 11 basic candidate flow points and their interval upper and lower bounds are summarized and merged, duplicate values ​​are removed, and the values ​​are sorted to form the final candidate flow set: {1.65, 1.75, 1.85, 1.95, 2.05, 2.15, 2.25, 2.35, 2.45, 2.55, 2.65, 2.75, 2.80} .

[0094] (2) Calculate the weakness score by dimension and screen it step by step.

[0095] The shortcomings score for each dimension is defined as a normalized constraint satisfaction score, ranging from 0 to 1. A higher shortcomings score indicates a better degree of constraint satisfaction for the corresponding dimension. Following the principle of absolute priority for ecological needs, five levels of dimensions are selected sequentially:

[0096] ① Screening for Ecological Response Dimension: The formula for calculating the score of shortcomings in the ecological response dimension is as follows: The preset threshold for this dimension is 0.95, because all candidate traffic sets... Therefore, all candidate traffic All of them will be retained.

[0097] ② Habitat suitability dimension screening: The formula for calculating the score of the habitat suitability dimension shortcomings is as follows: The preset threshold for this dimension is 0.70. The habitat suitability dimension weakness score for each candidate flow is calculated as follows:

[0098] hour, ,disuse;

[0099] hour, ,disuse;

[0100] hour, ,disuse;

[0101] hour, ,reserve;

[0102] After this level of filtering, the remaining candidate traffic set is: {1.95, 2.05, 2.15, 2.25, 2.35, 2.45, 2.55, 2.65, 2.75, 2.80} .

[0103] ③ Hydrological statistics dimension screening: The formula for calculating the weakness score of hydrological statistics dimension is: The preset threshold for this dimension is 0.80, since the remaining candidate traffic is much greater than 0.574. All scores of 1.0 ≥ 0.80 are retained.

[0104] ④ River morphology dimension screening: The formula for calculating the shortcoming score of the river morphology dimension is as follows: The preset threshold for this dimension is 0.80. Similarly, all remaining candidate traffic scores are 1.0≥0.80 and are all retained.

[0105] ⑤ Optimization of Human Activities and Ecological Risk Dimensions: After the first four levels of screening, 10 candidate flows remain. It is necessary to calculate the weakness scores of the human activities and ecological risk dimensions for each candidate flow. Among them, the score for water displacement pressure is: ,constraint Ecological risk mitigation score: ,constraint The scores for each candidate flow are shown in Table 1 below.

[0106] Table 1:

[0107] As shown in Table 1, the maximum score for the weakness in the human activities and ecological risk dimension is 0.435, corresponding to a candidate flow of 2.15. Therefore, the dry season ecological base flow at this control section was ultimately determined to be 2.15. .

[0108] The results of this embodiment show that the method can effectively solve the problems of single-dimensional bias and subjective weighting in the calculation of ecological baseflow in arid and semi-arid regions. Under the premise of strictly protecting the ecological survival red line, it achieves the optimal balance between ecological security and human production and living water use. The calculation results are scientific and reasonable and can be directly applied to the practice of refined watershed water resource management and ecological protection.

[0109] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them; modifications to the technical solutions described in the foregoing embodiments, or equivalent substitutions of some of the technical features, do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method for calculating the ecological base current during the dry season in arid and semi-arid regions, characterized in that, Includes the following steps: S1. Obtain basic data of the target river channel control section, including long-term dry season daily runoff data, river channel cross-section data, ecological monitoring data, and watershed human activity data; S2. Based on long-sequence dry season daily runoff data and river cross-section data, execute the first calculation strategy to generate basic ecological base flow; S3. Based on ecological monitoring data, execute the second calculation strategy to form a recommended ecological base flow range; S4. Determine whether the basic ecological base flow falls within the recommended ecological base flow range. If the basic ecological base flow falls within the recommended ecological base flow range, then determine that the basic ecological base flow is the dry season ecological base flow; otherwise, proceed to S5. S5. Construct a candidate flow set, calculate the bottleneck constraint indicators in different dimensions, and screen them step by step according to the multi-level priority of ecological priority to determine the ecological base flow in the dry season.

2. The method for calculating the ecological base current during the dry season in arid and semi-arid regions according to claim 1, characterized in that, In S1, the long-sequence dry season daily runoff data is the daily runoff from November to April of the following year for at least 15 consecutive years. The ecological monitoring data includes groundwater depth data, riparian vegetation coverage data, and dissolved oxygen data. The watershed human activity data includes watershed water resource development and utilization rate data and ecological risk level data.

3. The method for calculating the ecological base current during the dry season in arid and semi-arid regions according to claim 1, characterized in that, In S2, the first calculation strategy is: Hydrological statistical thresholds were calculated using the modified Tennant method based on long-sequence daily runoff data during the dry season. Based on cross-sectional data of the river channel, the wetted perimeter method is used to calculate the river channel morphology threshold. The maximum value between the hydrological statistical threshold and the river morphology threshold is taken as the basic ecological baseflow.

4. The method for calculating the dry season ecological base current in arid and semi-arid regions according to claim 3, characterized in that, The calculation process of the modified Tennant method is as follows: Calculate the average dry season flow over many years; Calculate the interannual correction factor; Hydrological statistical thresholds are calculated based on the average dry season flow over many years and the interannual correction factor.

5. The method for calculating the dry season ecological base current in arid and semi-arid regions according to claim 3, characterized in that, The calculation process of the wetted perimeter method is as follows: Plot the relationship curve between wetted perimeter and flow rate; The inflection point of the relationship curve is determined by the maximum curvature method, and the flow rate corresponding to the inflection point is the channel morphology threshold. If the width-to-depth ratio of the river channel is greater than 20, then the correction factor for the width-to-shallow channel shall apply. The river channel morphology threshold is corrected, and the correction coefficient for the wide and shallow river channel is... The value range is 1.05-1.

15.

6. The method for calculating the dry season ecological base current in arid and semi-arid regions according to claim 1, characterized in that, In S3, the second calculation strategy is: Based on ecological monitoring data, the lower limit of the ecological threshold is calculated using the eco-hydrological response method. ; Based on cross-sectional data of the river channel and the habitat suitability curve of the target species, the CASiMiR model was used to calculate the upper limit of habitat suitability. ; by This is the recommended ecological base flow range.

7. The method for calculating the ecological base current during the dry season in arid and semi-arid regions according to claim 6, characterized in that, The calculation process of the eco-hydrological response method is as follows: Quantitative response relationships between groundwater depth, riparian vegetation coverage, and dissolved oxygen in water bodies and flow rate were established respectively. Based on the quantitative response relationship, the critical flow rates for groundwater depth, riparian vegetation coverage, and dissolved oxygen in water were calculated respectively. The minimum critical flow rate is taken as the lower limit of the ecological threshold.

8. The method for calculating the dry season ecological base current in arid and semi-arid regions according to claim 1, characterized in that, In S5, the candidate traffic set is constructed as follows: The lower limit of the ecological threshold is used as the lower boundary of the interval, and the larger value between the upper limit of the habitat suitability and the basic ecological base flow is used as the upper boundary of the interval to form a closed effective flow interval. Within the closed effective flow range, N basic candidate flow points are evenly selected at equal intervals. All basic candidate flow points, as well as the candidate flows corresponding to the lower and upper bounds of the range, are aggregated and merged. Duplicate candidate flows are removed and sorted in ascending order to form a candidate flow set.

9. The method for calculating the dry season ecological base current in arid and semi-arid regions according to claim 1, characterized in that, In S5, the rule for multi-level priority selection based on ecological priority is as follows: Following the principle of absolute priority for ecological needs, all candidate flows in the candidate flow set are progressively screened in order of priority from highest to lowest: ecological response dimension, habitat suitability dimension, hydrological statistics dimension, river morphology dimension, and human activities and ecological risks dimension. Each level of screening retains candidate flows whose corresponding dimension's shortcoming score meets the preset threshold. If one candidate flow remains after the first four levels of screening, that candidate flow is taken as the dry season ecological base flow; otherwise, the candidate flow with the highest shortcoming score in the human activity and ecological risk dimension is selected as the dry season ecological base flow. If multiple candidate flows have the same score for the human activity and ecological risk dimension shortcomings and are the highest, then the candidate flow with the smallest score is selected as the dry season ecological base flow.

Images