Segmented hydrological simulation-based runoff change attribution nonlinear contribution identification method

Abstract

The invention discloses a runoff change attribution nonlinear contribution identification method based on segmented hydrological simulation. The method comprises the following steps: dividing an annual runoff sequence into a natural period and a human activity influence period; selecting a watershed hydrological model, and respectively calibrating parameters of the watershed hydrological model in a natural period and a human activity influence period by using hydrometeorological data; analyzing the influence of climate change on runoff change; analyzing the influence of human activities on runoff changes; combining the influence of the climate change and the human activity on the runoff change, and analyzing the synergistic effect of the climate change and the human activity on the runoff change; and quantifying the contribution rate of climatic change, human activity and synergistic effect of the climatic change and the human activity to runoff change. According to the method, on the basis of runoff change attribution linear analysis, the synergistic effect of climatic changes and human activities is recognized in an emphasized manner, the recognition result can objectively reflect the nonlinear response of the hydrological process to environmental elements, and the method is effectively applied to the specific work of watershed water resource evaluation and management.

Description

Technical Field

[0001] The invention relates to the technical field of runoff change analysis, and in particular to a runoff change attribution nonlinear contribution identification method based on segmented hydrological simulation. Background Art

[0002] As the climate warms, rising temperatures and changes in precipitation lead to changes in the hydrological cycle of river basins, which in turn have a direct impact on the spatial and temporal distribution of water resources. As human activities increase, the increase in industrial and agricultural water use will directly affect the regional water resources situation, and changes in land use will also have a certain impact on runoff conditions. Under the influence of climate change and human activities, the measured runoff of major rivers in the world has changed to a certain extent, especially in arid and semi-arid areas. In recent decades, the measured runoff has decreased significantly compared with the previous period, which has seriously restricted the stable development of the economy and society and brought new challenges to the management of river basin water resources.

[0003] Scientifically and accurately quantifying and evaluating the causes of river runoff changes is of great significance and practical value for regional water resources evaluation, scientific basin governance and water resources management. Therefore, the study of runoff change attribution under a changing environment is a scientific issue of great concern to hydrological researchers and basin managers. Basin hydrological simulation is the most widely used approach in the study of runoff change attribution due to its advantages such as convenient and fast application, relatively few data requirements, low time consumption and low labor resource costs. However, the identification of runoff change attribution based on the basin hydrological simulation approach linearly superimposes the runoff change attribution with the impact of climate change and human activities, and lacks consideration of the synergistic driving of climate change and human activities, resulting in inaccurate analysis results. Summary of the invention

[0004] Purpose of the invention: In view of the above problems, the purpose of the present invention is to provide a method for identifying the nonlinear contribution of runoff change attribution based on segmented hydrological simulation.

[0005] Technical solution: A method for identifying nonlinear contributions of runoff change attribution based on segmented hydrological simulation of the present invention comprises: Collect long-sequence hydrological and meteorological data and human activity data in the basin since the establishment of the station, calculate the annual runoff sequence of the basin, use mathematical and statistical methods to diagnose the mutation points of the annual runoff sequence, and divide the annual runoff sequence into natural periods and periods affected by human activities according to the mutation points; Select a basin hydrological model and use hydrological and meteorological data to calibrate the parameters of the basin hydrological model in the natural period and the period affected by human activities; The basin hydrological model calibrated with the hydrological and meteorological data of the natural period is used to simulate the runoff process of the entire period. The runoff during the natural period is used as the benchmark value, and the simulated runoff during the period of human activities is compared to analyze the impact of climate change on runoff changes. The basin hydrological model calibrated with hydrological and meteorological data during the period of human activities is used to simulate the runoff process of the entire period. The runoff during the natural period is used as the benchmark value, and the simulated runoff during the natural period is compared to analyze the impact of human activities on runoff changes. Combine the impacts of climate change and human activities on runoff change, and analyze the synergistic effects of climate change and human activities on runoff change; Quantify the contribution of climate change, human activities, and their synergy to streamflow changes.

[0006] Furthermore, the basin hydrological model is recorded as the response function , the natural period is taken as state A, and the climate elements of this period are recorded as CA , human activity status is recorded as HA , the runoff response is recorded as QA , then the runoff in the natural period is: , The period of human activities is regarded as state B, and the climate elements of this period are recorded as CB , human activity status is recorded as HB , the runoff response is recorded as QB , then the runoff during the period of human activity influence can be expressed as: .

[0007] Furthermore, the expression for analyzing the impact of climate change on runoff change is: , In the formula, is the impact of climate change on runoff change, is the runoff under natural conditions in state A and climate conditions in state B, is the average runoff during the period of human activities simulated based on natural period parameters, is the average runoff in the natural period simulated based on the natural period parameters.

[0008] Furthermore, the expression for analyzing the impact of human activities on runoff changes is: , In the formula, is the impact of human activities on runoff change, is the runoff under the climate conditions of state A and the human activity conditions of state B, It is the average runoff during the natural period simulated based on the parameters of the period affected by human activities.

[0009] Furthermore, combining the impact of climate change and human activities on runoff change, the synergistic effects of climate change and human activities on runoff change are analyzed as follows: Taking the natural period state A as the benchmark, when the climate elements and human activities of state A change to state B, the runoff will change accordingly. The total runoff change is expressed as: , Changes in runoff It is driven by two factors: the change of climate elements from state A to state B and the change of human activities from state A to state B. Therefore, the total amount of runoff change is also expressed as: , The impact of climate change and human activities on runoff change is It is expressed as: .

[0010] Furthermore, the contribution of climate change, human activities and their synergy to runoff changes is quantified as follows: The contribution rate of climate change to runoff change is calculated as follows: , Calculate the contribution rate of human activities to runoff change, the expression is: , The contribution rate of the synergistic effects of climate change and human activities to runoff change is calculated as follows: .

[0011] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: Based on the linear analysis of runoff change attribution, the present invention focuses on identifying the synergistic effect of climate change and human activities. The identification results of this method can objectively reflect the nonlinear response of hydrological processes to environmental factors and can be effectively applied to the specific work of basin water resources evaluation and management. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 The measured annual runoff from 1955 to 1995 at Huaxian Station in the Weihe River Basin and its 5-year moving average process curve; Figure 2 It is the process curve of the sum of squares of the measured annual runoff coefficients in the Weihe River Basin from 1955 to 1995; Figure 3 A flowchart of the nonlinear contribution identification method for runoff change attribution based on segmented hydrological simulation; Figure 4The measured and simulated monthly flow process curves of the Huaxian Station of the Weihe River during the natural period; Figure 5 These are the measured and simulated monthly flow process curves at the Huaxian Station of the Weihe River during the period of human activity impact. DETAILED DESCRIPTION

[0013] In order to make the objectives, technical solutions and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0014] The method for identifying nonlinear contributions of runoff change attribution based on segmented hydrological simulation described in this embodiment includes the following steps: Step 1: Collect long-sequence hydrological and meteorological data and human activity data in the basin since the establishment of the station, calculate the annual runoff sequence of the basin, use mathematical and statistical methods to diagnose the mutation points of the annual runoff sequence, and divide the annual runoff sequence into natural periods and periods affected by human activities according to the mutation points.

[0015] The long-sequence hydrological and meteorological data in the basin include runoff, precipitation, water surface evaporation and temperature. Human activity data include water conservancy projects, industrial and agricultural water withdrawal and water consumption data. The annual runoff sequence of the basin is calculated based on the hydrological and meteorological data, which consists of years and corresponding runoff coefficients. Mathematical and statistical methods such as Mann-Kendall mutation test and ordered cluster analysis are used to diagnose the mutation points of the annual runoff sequence. Combined with the human activities in the basin, the sequence is divided into a natural period and a period affected by human activities, that is, the period before the mutation point is called the natural period, and the period after the mutation point is called the period affected by human activities.

[0016] Step 2: Select the basin hydrological model and use the hydrological and meteorological data to calibrate the parameters of the basin hydrological model in the natural period and the period affected by human activities.

[0017] According to the actual conditions of each river basin, an appropriate river basin hydrological model is selected. The meteorological and hydrological data of the natural period and the period affected by human activities are used to calibrate the river basin hydrological model parameters in the natural period and the period affected by human activities respectively, and the effectiveness of the model in different periods is verified.

[0018] The Nash-Sutcliffe efficiency coefficient and relative error RE are used as indicators to evaluate the effectiveness of the basin hydrological model at different stages of the basin. In order to avoid the impact of simulation bias on runoff attribution identification, the total runoff simulation error is required to be within ±2% and the Nash-Sutcliffe efficiency coefficient is required to exceed 0.6. The calculation formulas for the two are as follows: , , In the formula, NSE is the efficiency coefficient, and Respectively i The measured and simulated average runoff during the period, is the simulated runoff volume, is the measured runoff, N is the total length of the runoff series, i.e. the total number of time periods.

[0019] Furthermore, the basin hydrological model is recorded as the response function , the natural period is taken as state A, and the climate elements of this period are recorded as CA , human activity status is recorded as HA , the runoff response is recorded as QA , then the runoff in the natural period is expressed as: , The period of human activities is regarded as state B, and the climate elements of this period are recorded as CB , human activity status is recorded as HB , the runoff response is recorded as QB , then the runoff during the period of human activity influence can be expressed as: .

[0020] Step 3: Use the basin hydrological model calibrated with the hydrological and meteorological data of the natural period to simulate the runoff process of the entire period. Take the runoff of the natural period as the baseline value, compare it with the simulated runoff during the period of human activities, and analyze the impact of climate change on runoff changes.

[0021] Based on the meteorological data of the natural period and the period affected by human activities, the basin hydrological model calibrated with the hydrological and meteorological data of the natural period simulates the natural runoff in the natural period and the period affected by human activities respectively. Taking the runoff in the natural period as the benchmark value, the impact of climate change on runoff change is analyzed, which is expressed as: , In the formula, is the impact of climate change on runoff change, is the runoff under natural conditions in state A and climate conditions in state B, is the average runoff during the period of human activities simulated based on natural period parameters, is the average runoff in the natural period simulated based on the natural period parameters.

[0022] The runoff process simulated based on the model parameters calibrated in the natural period and the full-process meteorological data is a hydrological response driven by different climatic factors under the same basin state conditions. The difference in runoff in different periods reflects the impact of differences in climatic factors.

[0023] and They are the runoff under the natural conditions of state A, the climate conditions of state B and state A respectively. The difference between the two reflects the change of runoff under the conditions of unchanged human activities and changing climate elements, and is therefore the response of runoff change under the single effect of climate change. Since the two are runoff under the same human activity conditions and different climate elements, the response function of runoff to climate elements and human activities can be determined by the hydrological and meteorological data of the natural period, that is, the parameters of the basin hydrological model can be calibrated, and then the climate data under the conditions of state B and state A can be used to drive the calibration, and then the runoff under different climate conditions can be calculated.

[0024] Step 4: Use the basin hydrological model calibrated with the hydrological and meteorological data during the period of human activity to simulate the runoff process of the entire period. Take the natural period runoff as the benchmark value, compare the simulated natural period runoff, and analyze the impact of human activities on runoff changes.

[0025] The basin hydrological model calibrated with the hydrological and meteorological data during the period of human activity impact is used to simulate the runoff process in the baseline period under the scenario of human activity impact. The runoff in the natural period is taken as the benchmark value to analyze the impact of human activities on runoff changes. The expression is: , In the formula, is the impact of human activities on runoff change, is the runoff under the climate conditions of state A and the human activity conditions of state B, It is the average runoff in the natural period simulated based on the parameters of the period affected by human activities. The climate factors driving it are all the base period, i.e. the natural period. The two respectively reflect the runoff under the same base period climate conditions and different situations of human activity influence. The difference reflects the impact of human activities on runoff.

[0026] For the same watershed, since the parameters of the response function of runoff to climate factors and human activities are mainly determined by the underlying surface of the watershed and the state of human activities, the response function parameters under the human activity conditions of state B are obtained by optimizing and calibrating the climate and hydrological data of the state B period, and then the calibrated response function is driven by the climate factor data under the conditions of state A, and then the runoff under the conditions of human activities in state B and state A is calculated. and It reflects the runoff under the same climate factors and different human activity conditions. Therefore, the difference between the two reflects the impact of changes in a single factor of human activity on runoff.

[0027] Step 5: Combine the impacts of climate change and human activities on runoff change to analyze the synergistic effects of climate change and human activities on runoff change.

[0028] Furthermore, combining the impact of climate change and human activities on runoff change, the synergistic effects of climate change and human activities on runoff change are analyzed as follows: Taking the natural period state A as the benchmark, when the climate elements and human activities of state A change to state B, the runoff will change accordingly. The total runoff change is expressed as: , Changes in runoff It is driven by two factors: the change of climate elements from state A to state B and the change of human activities from state A to state B. Therefore, the total amount of runoff change is also expressed as: , The impact of climate change and human activities on runoff change is It is expressed as: .

[0029] Step 6: Quantify the contribution of climate change, human activities, and their synergy to runoff changes.

[0030] Furthermore, the contribution of climate change, human activities and their synergy to runoff changes is quantified as follows: The contribution rate of climate change to runoff change is calculated as follows: , Calculate the contribution rate of human activities to runoff change, the expression is: , The contribution rate of the synergistic effects of climate change and human activities to runoff change is calculated as follows: .

[0031] The core of the nonlinear contribution identification method for runoff change attribution based on segmented hydrological simulation described in the present invention is: (1) based on the annual runoff sequence, the study period is divided into a natural period and a period affected by human activities; (2) a suitable watershed hydrological model is used to calibrate the model parameters of the natural period and the period affected by human activities, and the effectiveness of the model is verified; (3) based on the model parameters of the natural period and the period affected by human activities, and the climate element data of the natural period and the period affected by human activities, the runoff process under different watershed states, i.e., different intensities of human activity impact and different climatic conditions is simulated; (4) based on the simulated runoff under different watershed states, i.e., different intensities of human activity impact and different climatic conditions, the contribution of climate change, human activities, and the synergistic driving of the two to runoff change is quantitatively analyzed.

[0032] To illustrate the effectiveness of the present invention, the following examples are used for further explanation. The Wei River is a first-level tributary of the Yellow River, with a drainage area of ​​106,498 above Huaxian Station. km 2 In this example, the Weihe River Basin is taken as an example. The specific analysis steps are as follows. The flowchart is as follows: Figure 3 As shown: (1) Collect hydrological and meteorological data from 1955 to 1995 in the Weihe River Basin, including runoff, precipitation, evaporation and temperature; human activity data in the basin, including water conservancy projects, land use data and water consumption data. Analyze the annual runoff process measured at Huaxian Station. Figure 1 As shown, the dotted line in the figure is the trend line, and its expression is y =-0.9864 x +91.595, and the slope -0.9864 indicates the degree of runoff reduction. The annual runoff sequence was calculated based on the annual runoff of Huaxian Station and the average annual precipitation of the basin area, and the ordinal cluster analysis method was used, such as Figure 2 The mutation point of the diagnostic annual runoff series is shown in 1970. Combined with the human activities in the basin, the natural period and the period of human activity influence in the basin are determined to be 1955 to 1970 and 1971 to 1995 respectively.

[0033] (2) The RCCC-WBM water balance model (Water Balance Model developed by Research Center for Climate Change, RCCC-WBM) was selected, and the model parameters were calibrated for the natural period and the period affected by human activities using the NSE coefficient and relative error RE as targets. The RCCC-WBM water balance model has the advantages of simple structure, fewer parameters, easy calibration, and a wide range of applicable climate conditions.

[0034] The efficiency coefficient NSE of the runoff simulation at the Huaxian Station of the Weihe River during the natural period, i.e., from 1955 to 1970, is 0.77, and the average relative error RE of the simulation over many years is -0.34; the efficiency coefficient NSE of the runoff simulation during the period of human activity impact, i.e., from 1971 to 1995, is 0.66, and the average relative error RE of the simulation over many years is -0.31%. The simulations during the natural period and the period of human activity impact are well matched with the measured runoff processes, such as Figures 4 to 5 As shown, it can be used to simulate the runoff process of the basin under natural conditions and under the influence of human activities.

[0035] (3) Based on the model parameters calibrated during the natural period and the full-process meteorological data, the natural runoff process during the natural period and the period affected by human activities is simulated. The runoff process during the natural period is used as the benchmark value to analyze the impact of climate change on runoff changes.

[0036] In this example, the model parameters calibrated based on the natural period simulated the runoff of 87.66 mm in the natural period from 1955 to 1970, and the runoff during the period of human activities from 1971 to 1995 was 83.37 mm. The impact of climate change on runoff was calculated to be -4.28 mm.

[0037] (4) Based on the model parameters calibrated during the period of human activity impact and the full-process meteorological data, the runoff process under the scenario of human activity impact is simulated. Combined with the natural runoff process in the natural period, the runoff process in the natural period is used as the benchmark value to analyze the impact of human activities on runoff changes.

[0038] In this example, the runoff in the natural period simulated by the model parameters calibrated based on the period of human activity impact is 67.23 mm, and the runoff in the natural period simulated by the model parameters calibrated based on the natural period is 87.66 mm. Therefore, the runoff impact caused by human activities is -20.43 mm.

[0039] (5) The runoff during the natural period, i.e., 1955 to 1970, simulated by the model parameters calibrated based on the natural period, was 87.66 mm. The runoff during the human activity period, i.e., 1955 to 1970, simulated by the model parameters calibrated based on the human activity period, was 59.79 mm. Based on the runoff during the natural period, the runoff reduction during the human activity period was 27.87 mm. The calculated impact of the synergistic effects of climate change and human activities on runoff change was -3.16 mm.

[0040] (6) Calculations show that the contribution rates of climate change, human activities and their synergy to runoff change are 15.4%, 73.3% and 11.3%, respectively.

[0041] The following conclusions can be drawn from the above examples: (1) The measured runoff at the Huaxian Station in the Weihe River Basin showed a decreasing trend from 1955 to 1995, and the measured runoff series changed suddenly in 1970. The study period can be divided into the natural period (1955 to 1970) and the period affected by human activities (1971 to 1995).

[0042] (2) Taking the natural period as the baseline, the measured runoff during the period of human activities decreased by 27.87 mm. The impact of human activities and climate change caused the annual runoff to decrease by 20.43 mm and 4.28 mm respectively. The synergistic effect of human activities and climate change on the runoff reduction was 3.16 mm.

[0043] (3) The contribution rates of climate change, human activities and their synergistic effect to the runoff reduction from 1971 to 1995 were 15.4%, 73.3% and 11.3%, respectively. Human activities were the main factor affecting the runoff reduction, and the synergistic driving effect of climate change and human activities further amplified their impacts by more than 10%.

[0044] (4) The traditional runoff change attribution analysis method based on hydrological simulation and natural runoff restoration can objectively give the impact of climate change on runoff. However, due to not considering the synergistic effect of climate change and human activities, the traditional runoff change attribution identification method magnifies the effect of human activities on runoff change to a certain extent. The method of the present invention, based on the traditional runoff change attribution analysis method, can not only quantify the impact of climate change on runoff, but also quantify the impact of human activities on runoff change and the synergistic effect of climate change and human activities on runoff change through runoff simulation. When the nonlinear characteristics of the basin hydrological response are obvious, the synergistic effect of climate change and human activities on runoff change will be more prominent and cannot be ignored.

Claims

1. A nonlinear contribution identification method for runoff change attribution based on segmented hydrological simulation, characterized in that: include: Collect long-sequence hydrological and meteorological data and human activity data in the basin since the establishment of the station, calculate the annual runoff sequence of the basin, use mathematical and statistical methods to diagnose the mutation points of the annual runoff sequence, and divide the annual runoff sequence into natural periods and periods affected by human activities according to the mutation points; Select a basin hydrological model and use hydrological and meteorological data to calibrate the parameters of the basin hydrological model in the natural period and the period affected by human activities; The basin hydrological model calibrated with the hydrological and meteorological data of the natural period is used to simulate the runoff process of the entire period. The runoff during the natural period is used as the benchmark value, and the simulated runoff during the period of human activities is compared to analyze the impact of climate change on runoff changes. The basin hydrological model calibrated with hydrological and meteorological data during the period of human activities is used to simulate the runoff process of the entire period. The runoff during the natural period is used as the benchmark value, and the simulated runoff during the natural period is compared to analyze the impact of human activities on runoff changes. Combine the impacts of climate change and human activities on runoff change, and analyze the synergistic effects of climate change and human activities on runoff change; Quantify the contribution of climate change, human activities, and their synergy to streamflow changes.

2. The method for identifying nonlinear contributions to runoff change attribution based on segmented hydrological simulation according to claim 1 is characterized in that: The basin hydrological model is expressed as a response function , the natural period is taken as state A, and the climate elements of this period are recorded as CA , human activity status is recorded as HA , the runoff response is recorded as QA , then the runoff in the natural period is: ， The period of human activities is regarded as state B, and the climate elements of this period are recorded as CB , human activity status is recorded as HB , the runoff response is recorded as QB , then the runoff during the period of human activity influence can be expressed as: 。 3. The method for identifying nonlinear contributions to runoff change attribution based on segmented hydrological simulation according to claim 2 is characterized in that: The expression for analyzing the impact of climate change on runoff change is: ， In the formula, is the impact of climate change on runoff change, is the runoff under natural conditions in state A and climate conditions in state B, is the average runoff during the period of human activities simulated based on natural period parameters, is the average runoff in the natural period simulated based on the natural period parameters.

4. The method for identifying nonlinear contributions to runoff change attribution based on segmented hydrological simulation according to claim 3 is characterized in that: The expression for analyzing the impact of human activities on runoff changes is: ， In the formula, is the impact of human activities on runoff change, is the runoff under the climate conditions of state A and the human activity conditions of state B, It is the average runoff during the natural period simulated based on the parameters of the period affected by human activities.

5. The method for identifying nonlinear contributions to runoff change attribution based on segmented hydrological simulation according to claim 4 is characterized in that: Combining the impact of climate change and human activities on runoff change, the synergistic effects of climate change and human activities on runoff change are analyzed as follows: Taking the natural period state A as the benchmark, when the climate elements and human activities of state A change to state B, the runoff will change accordingly. The total runoff change is expressed as: ， Changes in runoff It is driven by two factors: the change of climate elements from state A to state B and the change of human activities from state A to state B. Therefore, the total amount of runoff change is also expressed as: ， The impact of climate change and human activities on runoff change is It is expressed as: 。 6. The method for identifying nonlinear contributions of runoff change attribution based on segmented hydrological simulation according to claim 5 is characterized in that: Quantifying the contribution of climate change, human activities, and their synergy to runoff changes includes: The contribution rate of climate change to runoff change is calculated as follows: ， Calculate the contribution rate of human activities to runoff change, the expression is: ， The contribution rate of the synergistic effects of climate change and human activities to runoff change is calculated as follows: 。

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