A method and model for analyzing multi-disaster comprehensive disaster prevention and mitigation effects of water conservancy and hydropower projects

Abstract

The application provides a water conservancy and hydropower engineering multi-disaster comprehensive disaster prevention and mitigation effect analysis method and analysis model, comprising: constructing a typical disaster event library corresponding to each natural disaster; based on the disaster occurrence frequency, constructing a typical disaster scene; simulating and deducing the typical disaster process to obtain an engineering disaster mitigation benefit probability distribution curve representing the correlation between the disaster occurrence frequency and the engineering disaster mitigation benefit, and then constructing a disaster mitigation benefit expectation; selecting a target engineering operation period, analyzing the comprehensive disaster mitigation benefit expectation curve to obtain an engineering cumulative disaster mitigation benefit value in the target engineering operation period. The application breaks through the limitation of the existing method which is only applicable to a single disaster, and can provide accurate, intuitive and quantitative technical support for loss analysis, emergency scheduling and emergency plan formulation of various natural disasters in a basin after the water conservancy and hydropower engineering is completed.

Description

Technical Field

[0001] This invention belongs to the field of water conservancy and hydropower engineering technology, specifically relating to a method and analysis model for analyzing the comprehensive disaster prevention and mitigation effects of multiple disasters in water conservancy and hydropower engineering. Background Technology

[0002] As crucial infrastructure, water conservancy and hydropower projects not only provide clean electricity for economic and social development but also make significant contributions to flood control, drought relief, and comprehensive disaster reduction. In recent years, with the increasing frequency of extreme weather events, the role of water conservancy and hydropower projects in disaster prevention and mitigation systems and emergency response capabilities has become increasingly prominent.

[0003] However, current disaster prevention and mitigation effect analyses of water conservancy and hydropower projects are limited to single disasters and use different quantitative indicators to evaluate the disaster prevention and mitigation effects of projects for specific disasters. They do not consider comprehensive disaster prevention and mitigation effect evaluation indicators applicable to multiple disaster couplings, and cannot intuitively reflect the comprehensive disaster prevention and mitigation effects after the project is completed. This results in incomplete and inaccurate analysis of the disaster prevention and mitigation economic benefits of water conservancy and hydropower projects. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method and model for analyzing the comprehensive disaster prevention and mitigation effects of multiple hazards in water conservancy and hydropower projects, which can effectively solve the aforementioned problems.

[0005] The technical solution adopted in this invention is as follows:

[0006] This invention provides a method for analyzing the comprehensive disaster prevention and mitigation effects of multiple hazards in water conservancy and hydropower projects, including:

[0007] Step S1: Based on the geographical location of the water conservancy and hydropower project, the characteristics of the river basin, and the climate characteristics of the region, determine the various natural disasters to be analyzed and several reference objects for damage.

[0008] Step S2: Analyze historical climate data of the areas affected by water conservancy and hydropower projects, and construct a model for each type of natural disaster. Corresponding typical disaster event database ;

[0009] Step S3, Set natural disasters The recurrence sequence of disasters; for natural disasters Recurrence period of each disaster The corresponding disaster occurrence frequency was calculated. The frequency of the disaster is used. For the aforementioned typical disaster event database Analysis was conducted to obtain the frequency of the disaster as described. Various typical disaster events form typical disaster scenarios. ;

[0010] Step S4, in each typical disaster scenario Simulations and simulations of typical disaster processes are conducted to obtain the disaster recurrence period. In the simulated scenario, the total loss caused by the disaster to each of the aforementioned damaged reference objects is the reduction in disaster loss compared to the total loss caused to each of the aforementioned damaged reference objects before the completion of the water conservancy and hydropower project. This represents the disaster reduction benefits of the project;

[0011] This establishes the frequency of disaster occurrence. With disaster loss reduction value The correlation between them;

[0012] Step S5: Analyze the frequency of various disasters. The obtained correlations are subjected to curve fitting to obtain a probability distribution curve of engineering disaster reduction benefits that characterizes the correlation between the frequency of each disaster and the engineering disaster reduction benefits, thereby constructing a system for dealing with each natural disaster. The probability density function of engineering disaster reduction benefits ;

[0013] Step S6, based on the situation of each natural disaster The probability density function of engineering disaster reduction benefits To build the expected disaster reduction benefits ;

[0014] Step S7, consider each type of natural disaster All are independent events that occur randomly. A stochastic model is used to study various natural disasters during different engineering operation periods t. Expected disaster reduction benefits A comprehensive analysis yielded the following project operation period: Expected comprehensive disaster reduction benefits ;

[0015] Step S8, change the different engineering operation periods Repeat steps S4 to S7 to obtain the expected comprehensive disaster reduction benefits. ~Engineering Operation Period The relevant curves were analyzed to obtain the expected curve of comprehensive disaster reduction benefits;

[0016] By selecting the target project operation period, the expected curve of the comprehensive disaster reduction benefits is analyzed to obtain the cumulative disaster reduction benefit value of the project during the target project operation period.

[0017] Furthermore, the natural disasters mentioned include flood disasters, geological disasters, and drought disasters.

[0018] Furthermore, in step S4, for flood disasters, the reduction value of disaster losses is... The calculation method is as follows:

[0019] Step A1, Typical Disaster Scenario For flood disasters, based on typical disaster scenarios The precipitation, peak flow, and process curves of the upstream basin were determined. Combined with the topography of the upstream and downstream basins, a hydrological analysis model was used to extrapolate the flood evolution curves before and after the completion of the hydropower project, and the highest flood level H along the route was determined. max The peak flow rate Q along the route and the staggered peak flow times of the main stream and tributaries are used to determine the flood inundation range and depth along the route.

[0020] Step A2: Based on the flood inundation range and depth along the course, extrapolate the actual damage reference objects and the number of damage reference objects that will cause damage during the flood disaster.

[0021] Step A3: Use the following formula to obtain the reduction value of disaster losses. :

[0022]

[0023] in: The total loss caused by flood disasters to the reference object after the completion of water conservancy and hydropower projects; The total loss caused by flood disasters to the reference object after the completion of water conservancy and hydropower projects;

[0024] This refers to the number of reference objects that caused actual damage during the sliding and collapse of unstable bodies before the completion of water conservancy and hydropower projects. For the first The unit price of loss for each damaged reference object. For the first The number of losses to each damaged reference object; For the first The submersion depth of a damaged reference object For the first The total height of each disruptive reference object;

[0025] This refers to the number of reference objects that cause actual damage during the sliding and collapse of unstable bodies after the completion of water conservancy and hydropower projects. For the first The unit price of loss for each damaged reference object. For the first The number of losses to each damaged reference object; For the first The submersion depth of a damaged reference object For the first The total height of the reference object that was destroyed.

[0026] Furthermore, in step S4, for geological disasters, the reduction value of disaster losses is... The calculation method is as follows:

[0027] Step B1, the typical disaster scenario For earthquake-related geological hazards, based on typical disaster scenarios Based on the peak ground acceleration zoning map, determine the ground ground acceleration g at the location of the disaster point. A The stability coefficient of the unstable body under earthquake conditions at the corresponding disaster recurrence period was calculated using the circular arc sliding method. For unstable bodies with stability coefficients lower than the standard requirements, the landslide volume and elevation were estimated based on satellite remote sensing imagery, and the post-landslide depositional elevation H was also estimated. d =-355.73+65.011×g×V d Where g is the acceleration due to gravity, and V d To estimate the volume of the landslide;

[0028] Step B2, based on the post-landslide accumulation elevation H d Assess the risk of the landslide dam breaking. If the risk of the landslide dam breaking is higher than the set threshold, proceed to step A3.

[0029] Step B3: Calculate the reservoir capacity of the barrier lake formed by the landslide blocking the river. :

[0030] =K1×S 坝 ×l y

[0031] Wherein: S 坝 The cross-sectional area of ​​the dam is estimated based on a triangular cross-section; y K1 represents the maximum backfilling length of the landslide dammed lake; K1 is the backfilling coefficient, and the greater the river slope, the smaller the value of K1.

[0032] Step B4: Simulate the dam failure of the landslide dam. Multiple disaster points are selected at equal intervals between the floodwaters released after the dam failure and the downstream water conservancy and hydropower projects. At each disaster point, the distance from the dam is set to l. The maximum flow rate at the dam failure is calculated using the following formula. and flood peak height :

[0033]

[0034]

[0035] in:

[0036] For the reservoir capacity of the landslide dammed lake; The maximum flow rate at the dam site; This represents the maximum flow velocity of the flood. This is an empirical coefficient; The maximum water depth at which the dam breaks; A is the cross-sectional coefficient of the valley at the disaster point, A=F / H, where F is the cross-sectional area and H is the cross-sectional height; The riverbed shape index, The riverbed gradient;

[0037] Step B5: Based on the maximum dam breakage flow rate at each disaster point. and flood peak height Based on topographic data, the ground elevation d0 at each disaster point is determined, and... x - d0 calculates the flood inundation range and inundation depth along the route from the landslide dam to the hydropower project. s ;

[0038] Step B6: Based on the flood inundation range and depth along the route, extrapolate the actual damage reference objects and their number during the unstable body sliding and collapse process. The following formula is used to obtain the disaster loss reduction value. :

[0039]

[0040] in: The total losses caused by flood disasters to the reference object before the completion of water conservancy and hydropower projects; The total loss caused by flood disasters to the reference object after the completion of water conservancy and hydropower projects;

[0041] This refers to the number of reference objects that caused actual damage during the sliding and collapse of unstable bodies before the completion of water conservancy and hydropower projects. For the first The unit price of loss for each damaged reference object. For the first The number of losses to each damaged reference object; For the first The submersion depth of a damaged reference object For the first The total height of each disruptive reference object; This refers to the number of reference objects that cause actual damage during the sliding and collapse of unstable bodies after the completion of water conservancy and hydropower projects. For the first The unit price of loss for each damaged reference object. For the first The number of losses to each damaged reference object; For the first The submersion depth of a damaged reference object For the first The total height of the reference object that was destroyed.

[0042] Furthermore, in step S4, for drought disasters, the reduction value of disaster losses is... The calculation method is as follows:

[0043] Step C1, the typical disaster scenario For typical drought disaster scenarios, a water resources extrapolation model considering the linkage of water conservancy and hydropower projects is constructed, using the basin rainfall, runoff, and water diversion volume of water conservancy and hydropower projects as boundary conditions.

[0044] Step C2: Using the water resource projection model, obtain the total natural water supply Q for each time period h in the water resource projection cycle. total,h , where Q total,h = Q h ’ +Q h +Q x,h Q h ’ Q h Q x,h , which are the surface runoff, soil runoff and groundwater runoff for time period h, respectively;

[0045] Step C3: At time h, obtain the regional water demand Q before the completion of the water conservancy and hydropower project. need,h,1 And the regional water demand Q after the completion of water conservancy and hydropower projects need,h,0 ;

[0046] Step C4: Use the following formula to obtain the water shortage Q in the region before the completion of the water conservancy and hydropower project. h,1 And the water shortage Q in the region after the completion of water conservancy and hydropower projects h,0 ;

[0047] Q h,0= Q need,h,0 - Q total,h

[0048] Q h,1 =Q need,h,1 -Q total,h

[0049] Step C5: Using the following formula, the reduction in regional water shortage ΔQ after the completion of the water conservancy and hydropower project is obtained. h,0 :

[0050] ΔQ h,0 = Q h,1 -Q h,0

[0051] Step C6, using the following formula, is based on the reduction in regional water shortage ΔQ after the completion of the water conservancy and hydropower project. h,0 Using three economic evaluation models for industrial, agricultural, and domestic water resources, the economic benefits corresponding to the reduction in water shortage are obtained, and thus the reduction in disaster losses is derived. ;

[0052] in = ;

[0053] , , These represent the reduction in water shortages for agriculture, industry, and domestic use, respectively. , , The economic benefits per unit of water use are calculated for agriculture, industry, and domestic use, respectively.

[0054] Furthermore, the water resources simulation model includes a surface runoff generation process simulation sub-model, an interflow runoff generation process simulation sub-model, and a groundwater runoff process simulation sub-model;

[0055] The sub-model for extrapolating surface runoff processes is as follows:

[0056]

[0057]

[0058]

[0059]

[0060]

[0061] in: Surface runoff; impermeable area The resulting runoff; Effective water volume; Permeable area The resulting runoff; It is an over-permeable flow; To accumulate sufficient flow; To maximize infiltration capacity; This refers to the excess amount of infiltration runoff. This represents the maximum water storage capacity of the soil. This represents the initial water cut flow rate at time period h-1; This refers to precipitation. This refers to the amount of water added artificially; This represents the evapotranspiration conversion factor; Evaporation amount; This indicates the amount of water that can be stored during time period h.

[0062] The sub-model for extrapolating the interflow process is as follows: The model converts soil water into four components: soil recharge to shallow groundwater, soil water storage, soil evapotranspiration, and interflow. The formulas are as follows:

[0063]

[0064]

[0065] in:

[0066] It indicates that the soil flows through the stream; This indicates the amount of water supplied to shallow groundwater. , These represent the soil moisture content at the beginning and end of the time period, respectively. , These represent the outflow coefficient from the soil and the recharge coefficient for shallow groundwater, respectively. This indicates the amount of water that can be stored during time period h.

[0067] The sub-model for extrapolating the underground runoff process is as follows: It calculates both deep and shallow underground reservoirs, and performs calculations for rapid and slow runoff, using the following formulas:

[0068]

[0069]

[0070]

[0071] In the formula: , These represent fast runoff and slow runoff, respectively. , These represent the shallow groundwater runoff coefficient and the deep groundwater runoff coefficient, respectively. , This indicates the water storage capacity of shallow and deep reservoirs over a given period. , These represent the initial water storage of shallow and deep reservoirs during the time period, respectively. , These represent the artificial water extraction volumes from shallow and deep reservoirs, respectively. , These represent the replenishment amounts of rivers and lakes, respectively. It is the shallow water infiltration coefficient.

[0072] Furthermore, in step S6, the expected disaster reduction benefits are obtained using the following formula. :

[0073]

[0074] in: and These are: natural disasters The minimum and maximum values ​​of disaster loss reduction obtained during all disaster recurrence periods.

[0075] Furthermore, step S7 specifically includes:

[0076] Selecting the recurrence period of the disaster In the probability density function of disaster reduction benefits in engineering Under the constraints, a random number generation algorithm is used to randomly generate each type of natural disaster. Disaster reduction benefit value ,in, The number of random samples;

[0077] The expected comprehensive disaster reduction benefits can be obtained through the following formula. :

[0078]

[0079] in: Types of natural disasters;

[0080] Simulating different project operation periods t, we obtain the expected comprehensive disaster reduction benefits corresponding to different project operation periods t. Thus, the correlation curve between the expected value of comprehensive disaster reduction benefits E(t) and the project operation period t is plotted, and the expected curve of comprehensive disaster reduction benefits E=f(t) of water conservancy and hydropower projects in the face of various natural disasters is obtained.

[0081] Furthermore, the cumulative disaster reduction benefit value of the project during its operation period is obtained using the following formula:

[0082] The cumulative disaster reduction benefit value of the project during its operation period ;

[0083] in: For the target project operation period; The expected comprehensive disaster reduction benefits are expressed as a curve function of the project's operating period t.

[0084] This invention also provides a multi-hazard integrated disaster prevention and mitigation effect analysis model for water conservancy and hydropower projects, which implements the aforementioned multi-hazard integrated disaster prevention and mitigation effect analysis method for water conservancy and hydropower projects, including:

[0085] The typical disaster event database construction module is used to determine various natural disasters to be analyzed and several damage reference objects based on the geographical location of water conservancy and hydropower projects, the characteristics of their watersheds, and the climate characteristics of the region; it analyzes historical climate data of the areas affected by water conservancy and hydropower projects to construct a database for each type of natural disaster. Corresponding typical disaster event database ;

[0086] Typical disaster scenario construction module, used to set up natural disasters The recurrence sequence of disasters; for natural disasters Recurrence period of each disaster The corresponding disaster occurrence frequency was calculated. The frequency of the disaster is used. For the aforementioned typical disaster event database Analysis was conducted to obtain the frequency of the disaster as described. Various typical disaster events form typical disaster scenarios. ;

[0087] The typical disaster process simulation module is used to simulate and extrapolate various typical disaster scenarios. Simulations and simulations of typical disaster processes are conducted to obtain the disaster recurrence period. In the simulated scenario, the total loss caused by the disaster to each of the aforementioned damaged reference objects is the reduction in disaster loss compared to the total loss caused to each of the aforementioned damaged reference objects before the completion of the water conservancy and hydropower project. This represents the disaster reduction benefits of engineering projects; from this, the frequency of disaster occurrence can be established. With disaster loss reduction value The correlation between them;

[0088] The module for constructing the probability density function of disaster reduction benefits in engineering projects is used to analyze the frequency of various disasters. The obtained correlations are subjected to curve fitting to obtain a probability distribution curve of engineering disaster reduction benefits that characterizes the correlation between the frequency of each disaster and the engineering disaster reduction benefits, thereby constructing a system for dealing with each natural disaster. The probability density function of engineering disaster reduction benefits ;

[0089] The disaster reduction benefit expectation building module is used to build upon the expected benefits of each type of natural disaster. The probability density function of engineering disaster reduction benefits To build the expected disaster reduction benefits ;

[0090] The comprehensive disaster reduction benefit expectation building module is used to consider each type of natural disaster. All are independent events that occur randomly. A stochastic model is used to study various natural disasters during different engineering operation periods t. Expected disaster reduction benefits A comprehensive analysis yielded the following project operation period: Expected comprehensive disaster reduction benefits ;

[0091] The module for constructing the expected curve of comprehensive disaster reduction benefits is used to modify the operation phase of different projects. Repeat steps S4 to S7 to obtain the expected comprehensive disaster reduction benefits. ~Engineering Operation Period The relevant curves are analyzed to obtain the expected curve of comprehensive disaster reduction benefits; the operation period of the target project is selected, and the expected curve of comprehensive disaster reduction benefits is analyzed to obtain the cumulative disaster reduction benefit value of the project during the operation period of the target project.

[0092] The method and model for analyzing the comprehensive disaster prevention and mitigation effects of multiple hazards in water conservancy and hydropower projects provided by this invention have the following advantages:

[0093] This invention provides a systematic, comprehensive, and intuitive method for analyzing the disaster prevention and mitigation effects of water conservancy and hydropower projects. It breaks through the limitation of existing methods that are only applicable to single disasters. It can provide accurate, intuitive, and quantitative technical support for loss analysis, emergency dispatch, and emergency plan formulation for water conservancy and hydropower projects in response to multiple natural disasters in the basin after completion. Attached Figure Description

[0094] Figure 1 A flowchart of a method for analyzing the comprehensive disaster prevention and mitigation effects of multiple hazards in water conservancy and hydropower projects provided by this invention;

[0095] Figure 2 A schematic diagram of the historical rainstorm and drought disaster event identification method provided by the present invention;

[0096] Figure 3 The probability distribution curve of comprehensive disaster reduction benefits in engineering provided by this invention;

[0097] Figure 4 The fitting curve of the expected annual comprehensive disaster reduction benefit (EAL) provided by the present invention;

[0098] Figure 5 The cumulative comprehensive disaster reduction benefit fitting curve provided by this invention. Detailed Implementation

[0099] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. It should be understood that the embodiments described below are only a part of the present invention, and not all of the embodiments. All other embodiments obtained based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0100] This invention provides a method and model for analyzing the comprehensive disaster prevention and mitigation effects of water conservancy and hydropower projects under multiple hazards. It is a quantitative analysis technology for the disaster mitigation effects of water conservancy and hydropower projects under multiple natural disasters in a watershed, which couples data analysis, mathematical statistics, and numerical simulation. It can provide technical support for the quantitative assessment of the disaster prevention and mitigation effects of water conservancy and hydropower projects under natural disasters in the watershed after their completion. Its results can be applied to risk prevention and control of cascade reservoir groups, emergency plan formulation, emergency response to chain disasters, and flood control and flood season planning.

[0101] This method includes five modules: regional water and drought disaster evolution characteristics analysis, geological disaster evolution law analysis, drought disaster loss analysis, flood disaster evolution analysis, and multi-hazard integrated disaster reduction benefit coupling. It comprehensively and systematically quantifies the loss characteristics of water conservancy and hydropower projects in the face of common natural disasters, constructs an economic evaluation model for the disaster prevention and mitigation benefits of engineering projects, and proposes methods and models for analyzing the multi-hazard integrated disaster prevention and mitigation effects of water conservancy and hydropower projects.

[0102] Analysis of the evolution characteristics of flood and drought disasters: Based on historical data from meteorological stations, a database of rainstorm and drought disaster events is constructed, and statistical downscaling methods are used to predict future climate evolution characteristics at the regional scale.

[0103] Geological hazard evolution pattern analysis: Optical and InSAR remote sensing interpretation is used to identify geological hazard points around the project, assess the risk of individual hazards and regional geological hazards, and clarify the changes in the geological hazard threats before and after the project construction;

[0104] Drought disaster loss analysis, based on the watershed water security rate and the regulation capacity of the cascade reservoir group, evaluates the drought resistance and disaster reduction benefits of the project;

[0105] Flood disaster evolution analysis: Based on HEC-RAS, a flood evolution analysis model is constructed to assess the impact of flood disasters on key downstream objects of the project;

[0106] The comprehensive disaster reduction benefits of multiple disasters are coupled. An economic evaluation model is constructed based on various disaster loss indicators. A cumulative distribution model of loss probability is constructed using economic indicators and the recurrence period of disaster occurrence. A method for analyzing the comprehensive disaster prevention and mitigation effects within the engineering construction baseline period is proposed.

[0107] This invention can systematically and directly evaluate the comprehensive disaster prevention and mitigation effects of water conservancy and hydropower projects on various natural disasters in the basin after completion, providing theoretical basis and technical support for the evaluation of the necessity and economic efficiency of project construction.

[0108] like Figure 1 As shown, this invention provides a method for analyzing the comprehensive disaster prevention and mitigation effects of multiple hazards in water conservancy and hydropower projects, including:

[0109] Step S1: Based on the geographical location of the water conservancy and hydropower project, the characteristics of the river basin, and the climate characteristics of the region, determine the various natural disasters to be analyzed and several damage reference objects; the natural disasters include, but are not limited to, flood disasters, geological disasters, and drought disasters.

[0110] Step S2: Analyze historical climate data of the areas affected by water conservancy and hydropower projects, and construct a model for each type of natural disaster. Corresponding typical disaster event database ;

[0111] Step S3, Set natural disasters The recurrence sequence of disasters; for natural disasters Recurrence period of each disaster The corresponding disaster occurrence frequency was calculated. The frequency of the disaster is used. For the aforementioned typical disaster event database Analysis was conducted to obtain the frequency of the disaster as described. Various typical disaster events form typical disaster scenarios. ;

[0112] Step S4, in each typical disaster scenario Simulations and simulations of typical disaster processes are conducted to obtain the disaster recurrence period. In the simulated scenario, the total loss caused by the disaster to each of the aforementioned damaged reference objects is the reduction in disaster loss compared to the total loss caused to each of the aforementioned damaged reference objects before the completion of the water conservancy and hydropower project. This represents the disaster reduction benefits of the project;

[0113] This establishes the frequency of disaster occurrence. With disaster loss reduction value The correlation between them;

[0114] In step S4, for flood disasters, the reduction value of disaster losses is... The calculation method is as follows:

[0115] Step A1, Typical Disaster Scenario For flood disasters, based on typical disaster scenarios The precipitation, peak flow, and process curves of the upstream basin were determined. Combined with the topography of the upstream and downstream basins, a hydrological analysis model was used to extrapolate the flood evolution curves before and after the completion of the hydropower project, and the highest flood level H along the route was determined. max The peak flow rate Q along the route and the staggered peak flow times of the main stream and tributaries are used to determine the flood inundation range and depth along the route.

[0116] Step A2: Based on the flood inundation range and depth along the course, extrapolate the actual damage reference objects and the number of damage reference objects that will cause damage during the flood disaster.

[0117] Step A3: Use the following formula to obtain the reduction value of disaster losses. :

[0118]

[0119] in: The total loss caused by flood disasters to the reference object after the completion of water conservancy and hydropower projects; The total loss caused by flood disasters to the reference object after the completion of water conservancy and hydropower projects;

[0120] This refers to the number of reference objects that caused actual damage during the sliding and collapse of unstable bodies before the completion of water conservancy and hydropower projects. For the first The unit price of loss for each damaged reference object. For the first The number of losses to each damaged reference object; For the first The submersion depth of a damaged reference object For the first The total height of each disruptive reference object;

[0121] This refers to the number of reference objects that cause actual damage during the sliding and collapse of unstable bodies after the completion of water conservancy and hydropower projects. For the first The unit price of loss for each damaged reference object. For the first The number of losses to each damaged reference object; For the first The submersion depth of a damaged reference object For the first The total height of the reference object that was destroyed.

[0122] In step S4, for geological disasters, the reduction value of disaster losses is... The calculation method is as follows:

[0123] Step B1, the typical disaster scenario For earthquake-related geological hazards, based on typical disaster scenarios Based on the peak ground acceleration zoning map, determine the ground ground acceleration g at the location of the disaster point. AThe stability coefficient of the unstable body under earthquake conditions at the corresponding disaster recurrence period was calculated using the circular arc sliding method. For unstable bodies with stability coefficients lower than the standard requirements, the landslide volume and elevation were estimated based on satellite remote sensing imagery, and the post-landslide depositional elevation H was also estimated. d =-355.73+65.011×g×V d Where g is the acceleration due to gravity, and V d To estimate the volume of the landslide;

[0124] Step B2, based on the post-landslide accumulation elevation H d Assess the risk of the landslide dam breaking. If the risk of the landslide dam breaking is higher than the set threshold, proceed to step A3.

[0125] Step B3: Calculate the reservoir capacity of the barrier lake formed by the landslide blocking the river. :

[0126] =K1×S 坝 ×l y

[0127] Wherein: S 坝 The cross-sectional area of ​​the dam is estimated based on a triangular cross-section; y K1 represents the maximum backfilling length of the landslide dammed lake; K1 is the backfilling coefficient, and the greater the river slope, the smaller the value of K1.

[0128] Step B4: Simulate the dam failure of the landslide dam. Multiple disaster points are selected at equal intervals between the floodwaters released after the dam failure and the downstream water conservancy and hydropower projects. At each disaster point, the distance from the dam is set to l. The maximum flow rate at the dam failure is calculated using the following formula. and flood peak height :

[0129]

[0130]

[0131] in:

[0132] For the reservoir capacity of the landslide dammed lake; The maximum flow rate at the dam site; This represents the maximum flow velocity of the flood. This is an empirical coefficient; The maximum water depth at which the dam breaks; A is the cross-sectional coefficient of the valley at the disaster point, A=F / H, where F is the cross-sectional area and H is the cross-sectional height; The riverbed shape index, The riverbed gradient;

[0133] Step B5: Based on the maximum dam breakage flow rate at each disaster point. and flood peak height Based on topographic data, the ground elevation d0 at each disaster point is determined, and... x - d0 calculates the flood inundation range and inundation depth along the route from the landslide dam to the hydropower project. s ;

[0134] Step B6: Based on the flood inundation range and depth along the route, extrapolate the actual damage reference objects and their number during the unstable body sliding and collapse process. The following formula is used to obtain the disaster loss reduction value. :

[0135]

[0136] in: The total losses caused by flood disasters to the reference object before the completion of water conservancy and hydropower projects; The total loss caused by flood disasters to the reference object after the completion of water conservancy and hydropower projects;

[0137] This refers to the number of reference objects that caused actual damage during the sliding and collapse of unstable bodies before the completion of water conservancy and hydropower projects. For the first The unit price of loss for each damaged reference object. For the first The number of losses to each damaged reference object; For the first The submersion depth of a damaged reference object For the first The total height of each disruptive reference object; This refers to the number of reference objects that cause actual damage during the sliding and collapse of unstable bodies after the completion of water conservancy and hydropower projects. For the first The unit price of loss for each damaged reference object. For the first The number of losses to each damaged reference object; For the first The submersion depth of a damaged reference object For the first The total height of the reference object that was destroyed.

[0138] In step S4, for drought disasters, the reduction value of disaster losses is... The calculation method is as follows:

[0139] Step C1, the typical disaster scenario For typical drought disaster scenarios, a water resources extrapolation model considering the linkage of water conservancy and hydropower projects is constructed, using the basin rainfall, runoff, and water diversion volume of water conservancy and hydropower projects as boundary conditions.

[0140] The water resources simulation model includes a surface runoff process simulation sub-model, an interflow runoff process simulation sub-model, and a groundwater runoff process simulation sub-model.

[0141] The sub-model for extrapolating surface runoff processes is as follows:

[0142]

[0143]

[0144]

[0145]

[0146]

[0147] in: Surface runoff; impermeable area The resulting runoff; Effective water volume; Permeable area The resulting runoff; It is an over-permeable flow; To accumulate sufficient flow; To maximize infiltration capacity; This refers to the excess amount of infiltration runoff. This represents the maximum water storage capacity of the soil. This represents the initial water cut flow rate at time period h-1; This refers to precipitation. This refers to the amount of water added artificially; This represents the evapotranspiration conversion factor; Evaporation amount; This indicates the amount of water that can be stored during time period h.

[0148] The sub-model for extrapolating the interflow process is as follows: The model converts soil water into four components: soil recharge to shallow groundwater, soil water storage, soil evapotranspiration, and interflow. The formulas are as follows:

[0149]

[0150]

[0151] in:

[0152] It indicates that the soil flows through the stream; This indicates the amount of water supplied to shallow groundwater. , These represent the soil moisture content at the beginning and end of the time period, respectively. , These represent the outflow coefficient from the soil and the recharge coefficient for shallow groundwater, respectively. This indicates the amount of water that can be stored during time period h.

[0153] The sub-model for extrapolating the underground runoff process is as follows: It calculates both deep and shallow underground reservoirs, and performs calculations for rapid and slow runoff, using the following formulas:

[0154]

[0155]

[0156]

[0157] In the formula: , These represent fast runoff and slow runoff, respectively. , These represent the shallow groundwater runoff coefficient and the deep groundwater runoff coefficient, respectively. , This indicates the water storage capacity of shallow and deep reservoirs over a given period. , These represent the initial water storage of shallow and deep reservoirs during the time period, respectively. , These represent the artificial water extraction volumes from shallow and deep reservoirs, respectively. , These represent the replenishment amounts of rivers and lakes, respectively. It is the shallow water infiltration coefficient.

[0158] Step C2: Using the water resource projection model, obtain the total natural water supply Q for each time period h in the water resource projection cycle. total,h , where Q total,h = Q h ’ +Q h +Q x,h Q h ’ Q h Q x,h , which are the surface runoff, soil runoff and groundwater runoff for time period h, respectively;

[0159] Step C3: At time h, obtain the regional water demand Q before the completion of the water conservancy and hydropower project. need,h,1 And the regional water demand Q after the completion of water conservancy and hydropower projects need,h,0 ;

[0160] Step C4: Use the following formula to obtain the water shortage Q in the region before the completion of the water conservancy and hydropower project. h,1 And the water shortage Q in the region after the completion of water conservancy and hydropower projects h,0 ;

[0161] Q h,0= Q need,h,0 - Q total,h

[0162] Q h,1 =Q need,h,1 -Q total,h

[0163] Step C5: Using the following formula, the reduction in regional water shortage ΔQ after the completion of the water conservancy and hydropower project is obtained. h,0 :

[0164] ΔQ h,0 = Q h,1 -Q h,0

[0165] Step C6, using the following formula, is based on the reduction in regional water shortage ΔQ after the completion of the water conservancy and hydropower project. h,0 Using three economic evaluation models for industrial, agricultural, and domestic water resources, the economic benefits corresponding to the reduction in water shortage are obtained, and thus the reduction in disaster losses is derived. ;

[0166] in = ;

[0167] , , These represent the reduction in water shortages for agriculture, industry, and domestic use, respectively. , , The economic benefits per unit of water use are calculated for agriculture, industry, and domestic use, respectively.

[0168] Step S5: Analyze the frequency of various disasters. The obtained correlations are subjected to curve fitting to obtain a probability distribution curve of engineering disaster reduction benefits that characterizes the correlation between the frequency of each disaster and the engineering disaster reduction benefits, thereby constructing a system for dealing with each natural disaster. The probability density function of engineering disaster reduction benefits ;

[0169] Step S6, based on the situation of each natural disaster The probability density function of engineering disaster reduction benefits To build the expected disaster reduction benefits ;

[0170] Specifically, the expected disaster reduction benefits are obtained using the following formula. :

[0171]

[0172] in: and These are: natural disasters The minimum and maximum values ​​of disaster loss reduction obtained during all disaster recurrence periods.

[0173] Step S7, consider each type of natural disaster All are independent events that occur randomly. A stochastic model is used to study various natural disasters during different engineering operation periods t. Expected disaster reduction benefits A comprehensive analysis yielded the following project operation period: Expected comprehensive disaster reduction benefits ;

[0174] Step S7 is as follows:

[0175] Selecting the recurrence period of the disaster In the probability density function of disaster reduction benefits in engineering Under the constraints, a random number generation algorithm is used to randomly generate each type of natural disaster. Disaster reduction benefit value ,in, The number of random samples;

[0176] The expected comprehensive disaster reduction benefits can be obtained through the following formula. :

[0177]

[0178] in: Types of natural disasters;

[0179] Simulating different project operation periods t, we obtain the expected comprehensive disaster reduction benefits corresponding to different project operation periods t. Thus, the correlation curve between the expected value of comprehensive disaster reduction benefits E(t) and the project operation period t is plotted, and the expected curve of comprehensive disaster reduction benefits E=f(t) of water conservancy and hydropower projects in the face of various natural disasters is obtained.

[0180] Step S8, change the different engineering operation periods Repeat steps S4 to S7 to obtain the expected comprehensive disaster reduction benefits. ~Engineering Operation Period The relevant curves are analyzed to obtain the expected curve of comprehensive disaster reduction benefits; the operation period of the target project is selected, and the expected curve of comprehensive disaster reduction benefits is analyzed to obtain the cumulative disaster reduction benefit value of the project during the operation period of the target project.

[0181] Specifically, the cumulative disaster reduction benefit value of the project during its operation period is obtained using the following formula:

[0182] The cumulative disaster reduction benefit value of the project during its operation period ;

[0183] in: For the target project operation period; The expected comprehensive disaster reduction benefits are expressed as a curve function of the project's operating period t.

[0184] This invention also provides a comprehensive disaster prevention and mitigation effect analysis model for water conservancy and hydropower projects, comprising:

[0185] The typical disaster event database construction module is used to determine various natural disasters to be analyzed and several damage reference objects based on the geographical location of water conservancy and hydropower projects, the characteristics of their watersheds, and the climate characteristics of the region; it analyzes historical climate data of the areas affected by water conservancy and hydropower projects to construct a database for each type of natural disaster. Corresponding typical disaster event database ;

[0186] Typical disaster scenario construction module, used to set up natural disasters The recurrence sequence of disasters; for natural disasters Recurrence period of each disaster The corresponding disaster occurrence frequency was calculated. The frequency of the disaster is used. For the aforementioned typical disaster event database Analysis was conducted to obtain the frequency of the disaster as described. Various typical disaster events form typical disaster scenarios. ;

[0187] The typical disaster process simulation module is used to simulate and extrapolate various typical disaster scenarios. Simulations and simulations of typical disaster processes are conducted to obtain the disaster recurrence period. In the simulated scenario, the total loss caused by the disaster to each of the aforementioned damaged reference objects is the reduction in disaster loss compared to the total loss caused to each of the aforementioned damaged reference objects before the completion of the water conservancy and hydropower project. This represents the disaster reduction benefits of engineering projects; from this, the frequency of disaster occurrence can be established. With disaster loss reduction value The correlation between them;

[0188] The module for constructing the probability density function of disaster reduction benefits in engineering projects is used to analyze the frequency of various disasters. The obtained correlations are subjected to curve fitting to obtain a probability distribution curve of engineering disaster reduction benefits that characterizes the correlation between the frequency of each disaster and the engineering disaster reduction benefits, thereby constructing a system for dealing with each natural disaster. The probability density function of engineering disaster reduction benefits ;

[0189] The disaster reduction benefit expectation building module is used to build upon the expected benefits of each type of natural disaster. The probability density function of engineering disaster reduction benefits To build the expected disaster reduction benefits ;

[0190] The comprehensive disaster reduction benefit expectation building module is used to consider each type of natural disaster. All are independent events that occur randomly. A stochastic model is used to study various natural disasters during different engineering operation periods t. Expected disaster reduction benefits A comprehensive analysis yielded the following project operation period: Expected comprehensive disaster reduction benefits ;

[0191] The module for constructing the expected curve of comprehensive disaster reduction benefits is used to modify the operation phase of different projects. Repeat steps S4 to S7 to obtain the expected comprehensive disaster reduction benefits. ~Engineering Operation Period The relevant curves are analyzed to obtain the expected curve of comprehensive disaster reduction benefits; the operation period of the target project is selected, and the expected curve of comprehensive disaster reduction benefits is analyzed to obtain the cumulative disaster reduction benefit value of the project during the operation period of the target project.

[0192] Two examples are described below:

[0193] A method for analyzing the multi-hazard disaster prevention and mitigation effects of water conservancy and hydropower projects, wherein the multi-hazards include at least two or more natural disasters, and include complex chain-like natural disasters. The steps of the method for analyzing the disaster prevention and mitigation effects of the project are as follows:

[0194] Step 1: Select the object of disaster reduction effect analysis and review the natural disaster situation around the project:

[0195] According to this invention, at least two or more natural disasters and chain disasters surrounding the project must be identified as the objects of analysis. Disaster information focuses on the disaster development process and losses, including the time of occurrence, cause, duration, relief efforts (personnel and economic input), and disaster losses (casualties, direct and indirect economic losses). A historical disaster database is established as verification data for subsequent model analysis and calculations, verifying the rationality and accuracy of the model calculations.

[0196] Step 2, Basic Data Collection and Determination:

[0197] According to the calculation and analysis requirements of this invention, the comprehensive disaster prevention and mitigation effect analysis of the project requires the collection of reservoir capacity-water level relationship curves and data of the cascade reservoir group in the basin where the project is located, historical data of meteorological stations around the project and in the basin (temperature, precipitation, wind speed, etc.), scheduling regulations of the project and the cascade reservoir group in the basin, socio-economic data of the study area (administrative area, population distribution, per capita / total GDP), and infrastructure data (number and distribution of farmland, airports, highways, railways, hospitals, schools and other important public infrastructure, number and distribution of residences). A disaster loss analysis reference index system consisting of socio-economic data and infrastructure data is established, consisting of a items. Each reference index is numbered i=1, 2, 3, ..., a, which serves as the basis for subsequent multi-hazard loss analysis calculations.

[0198] Step 3, Analysis of the Evolution Characteristics of Floods and Droughts:

[0199] Based on the natural disaster event database constructed according to this invention, the characteristics and future evolution trends of natural disasters in the research area are analyzed. Its focus is:

[0200] 1) Based on the historical data (daily precipitation q, temperature T) collected in step 2 from meteorological stations around the project and in the watershed, 温 This system identifies rainstorm and drought events and combines data from adjacent spatial stations and different time periods to form a rainstorm and drought event database. The database data must meet the following requirements: daily precipitation q ≥ 50 mm (rainstorm disaster); distance between stations ≤ 350 km is defined as a "neighboring station"; the number of rainstorm / drought stations ≥ 0.8% of the effective number of "neighboring stations" is defined as a regional rainstorm / drought "station group"; the center distance between the current day's regional rainstorm / drought station group and the previous day's regional rainstorm / drought station group is ≤ 1050 km, defining the station group events as continuous, and these are recorded as regional rainstorm / drought weather processes respectively.

[0201] 2) Analyze the characteristics of rainstorm and drought events:

[0202] Based on the rainstorm and drought event database constructed in step 1), targeting the disaster intensity (q, T) 温The distribution area and duration (t) of the events were summarized to determine the trend of event changes. The frequency of different levels of rainstorm and drought events was statistically determined, and the probability of occurrence (P) was determined by frequency analysis, and the return period (T=1 / P) was proposed. Using the high-resolution regional climate model (RegCM4) simulation analysis tool, future climate change was predicted based on greenhouse gas emission data, providing basic data support for subsequent disaster risk assessment and disaster prevention and mitigation effect analysis.

[0203] Step 4, Analysis of Geological Disaster Prevention and Mitigation Effects:

[0204] Based on the geological hazard impact object and economic evaluation model proposed in this invention, the disaster prevention and mitigation effects of the project on geological hazards and chain disasters after its completion are clarified.

[0205] 1) Identification of potential geological hazards: Based on remote sensing, survey and field investigation data, identify geological hazard points around the project and clarify their type, location, whether they involve water, scale and stability;

[0206] 2) Analysis of the impact of conventional geological hazards: Based on the socio-economic development, population and infrastructure data of the study area collected in step 2, identify the objects that may be affected by the identified geological hazards, delineate the high, medium and low risk zones of the hazard impact, and analyze the changes in the number of hazard points and the area of ​​risk zones based on the changes in the water level and geological conditions of the basin before and after the construction of water conservancy projects.

[0207] 3) Disaster Evolution Analysis: This includes three analytical components: stability calculation, scale calculation, and dam failure evolution calculation. Different return periods (T) are selected. A Earthquake conditions of 5, 10, 20, 50, 100, 500, 1000, and 10000 years, based on the national peak ground acceleration zoning map, determine the seismic ground acceleration (g) at the location of the disaster point. A The stability coefficient of the unstable body under earthquake conditions with the corresponding return period is calculated using the simplified Bishop method or the circular slip method. For unstable bodies with stability coefficients lower than the standard requirements, the landslide volume and elevation are estimated based on satellite remote sensing imagery, and the post-landslide depositional elevation H is also estimated. d =-355.73+65.011×g×V d Where g is the acceleration due to gravity, and V d To estimate the volume of the landslide, subsequent disaster impact analysis and calculations will be performed.

[0208] ① Scale Calculation. The following formula is used to calculate the reservoir capacity of the barrier lake formed by the landslide blocking the river:

[0209] =K1×S 坝 ×l y

[0210] In the formula, The reservoir capacity of the landslide dammed lake (m 3 ); S 坝 The cross-sectional area of ​​the dam body (m²) 2 Estimate based on triangular cross-section; l y The maximum backfilling length (m) of the landslide dammed lake can be estimated based on the highest elevation of the landslide dam as the inundation range; K1 is the backfilling coefficient. The greater the river slope, the smaller the K1 value. It is generally taken as 0.1~0.2, and 0.12 is taken in this case.

[0211] ② Dam break evolution calculation. This mainly calculates the impact of the floodwater released after the landslide dam breaks on downstream areas and hydropower stations, including the calculation of maximum peak flow and flood height. The formula for calculating the maximum peak flow is as follows:

[0212]

[0213] In the formula: Q l,max The maximum flow rate (m³) at a distance of l (m) from the landslide dam is the maximum flow rate at which the dam breaks. 3 / s); W is the reservoir capacity of the landslide dammed lake (m). 3 ); Q max Maximum flow rate at the dam site (m³) 3 / s); V max K1 represents the maximum flow velocity of the flood; K2 is an empirical coefficient.

[0214] The maximum flood height is calculated by estimating the flood level of the analyzed object (hydropower station / water conservancy project) when the floodwater released from the landslide dam reaches it, in order to determine whether there is a risk of dam overtopping or even further dam failure. The formula for calculating the maximum flood height is as follows:

[0215]

[0216] In the formula: H1 is the peak flood height (m) at a distance l from the landslide dam; H1 is the maximum water depth at the dam breach (m); A is the valley cross-sectional coefficient, A=F / H (F is the cross-sectional area / m²). 2 H is the cross-sectional height (m); i0 is the riverbed gradient; W is the reservoir capacity of the landslide dam (m); l is the downstream distance from the landslide dam (m); n is the riverbed shape index.

[0217] 4) Calculation of disaster prevention and mitigation benefits: This includes analysis of the damage reference object and calculation of the reduction benefits.

[0218] ① Analysis of reference objects for damage: Under two working conditions, before and after the construction of the water conservancy and hydropower project, the peak flood height at different locations upstream and downstream of the hydropower station / water conservancy project after the landslide dam breaks is calculated at 1km intervals. Based on topographic data, the ground elevation d0 of each calculation point is determined. - d0 calculates the flood inundation range and inundation depth along the route from the landslide dam to the hydropower project. s The number of reference objects n that are destroyed during the sliding and collapse of an unstable body is simulated. i (Item a, the disaster loss analysis reference indicator determined in step (2));

[0219] ② Loss Reduction Benefit Calculation: Compare and analyze the changes in the number of damaged reference objects before and after the project construction, and determine the unit loss price p of damaged objects in the geological disaster-affected area based on the statistical yearbook of the reference region and extensive experience standards. i The disaster prevention and mitigation benefits are calculated according to the following formula:

[0220]

[0221] In the formula, ΔP represents the disaster prevention and mitigation benefits of the water conservancy and hydropower project, P1 represents the losses caused by disasters before project construction, P0 represents the losses caused by disasters after project construction, and p i Let n be the unit price of loss for the reference object of the i-th type of damage. i，1 d represents the amount of damage to a reference object before construction. s，1 H serves as the reference submersion depth before project construction. i n represents the total height of the reference object. i，0 The amount of damage to the reference object after the project construction. This refers to the submersion depth of the reference object after project construction. For infrastructure with a certain height, such as residential buildings and stations, the depth is H. i and the submerged water depth d s The ratio between the values ​​is used to calculate the actual damage loss of the object, thus improving the accuracy of the calculation.

[0222] 5) Establishment of probability density curves for geological hazard prevention and mitigation benefits in water conservancy projects:

[0223] Based on the return period of earthquake conditions (T) A ) Calculate the frequency of geological disasters (P) A =1 / T A ), and the reduction in losses caused by geological disasters (L) A =ΔP) corresponds one-to-one, and P is fitted with the standard exponential distribution, logarithmic distribution, normal distribution, Weibull distribution, and log-normal distribution, respectively. A —L A By finding the distribution function with the highest degree of fit, we can construct the statistical distribution curve of engineering geological disaster reduction benefits and the corresponding probability density function (f). A (L) A The formula for calculating the expected disaster reduction benefits is as follows:

[0224]

[0225] Step 5: Analysis of drought disaster prevention and mitigation effects.

[0226] Based on the drought evaluation index system and economic evaluation model proposed in this invention, the drought resistance and disaster reduction effects of engineering projects are clarified. The construction of the drought resistance and disaster reduction capacity evaluation index system for engineering projects is as follows: Based on the adverse effects of drought disasters on the entire watershed, the evaluation index system for the drought resistance and disaster reduction capacity of engineering projects is constructed from three aspects: drought resistance capacity, drought resistance effect, and disaster reduction effect. This system addresses the operational conditions of water conservancy and hydropower projects in the watershed, engineering benefits, socio-economic water demand, and drought disaster losses.

[0227] 1) Drought disaster analysis scenario formulation: Based on the drought disaster event database established in step 2, frequency analysis of watershed runoff is performed to establish the annual runoff Q. B ~Occurrence frequency P B The relationship curve is used to determine the return period (T) of drought disasters based on the return period of annual runoff. B Establish drought disaster analysis scenarios of different levels (recurrence period) and clarify the watershed rainfall, runoff, and water diversion volume of water conservancy projects within the scenarios;

[0228] 2) Analysis of water use situation evolution in the basin: A water resources projection model considering the linkage between water conservancy and hydropower projects in the basin is constructed using the basin rainfall, runoff, and water diversion volume of water conservancy projects in a drought scenario as boundary conditions.

[0229] First, the surface runoff process is calculated: Considering the underlying surface conditions of the watershed, the unit surface runoff area is divided into two parts for calculation: permeable runoff area and impermeable runoff area. A combined runoff method is used on permeable surfaces, while precipitation on impermeable surfaces needs to be subtracted for evaporation before surface runoff is generated. The surface runoff calculation formula is as follows:

[0230]

[0231]

[0232]

[0233]

[0234]

[0235] In the formula:

[0236] Surface runoff (m 3 ); impermeable area (m) 2 Runoff generated by ) (m 3 ); Effective water volume (mm); Permeable area The generated runoff (m 3 ); It is an over-permeable flow; To accumulate sufficient flow; Maximum infiltration capacity (m) 3 ); The excess infiltration runoff (m 3 ); Maximum water storage capacity of soil (m 3 ); The initial water cut flow rate (m³) at time period h-1 is represented by the initial water cut flow rate (m³). 3 ); Rainfall (mm); The amount of water replenished artificially (mm); This represents the evapotranspiration conversion factor; Evaporation rate (mm); This indicates the water storage capacity (m³) during time period h. 3 (This model uses 1 year for calculation).

[0237] Next, the interflow process was calculated. The model converts soil water into four components: soil recharge to shallow groundwater, soil water storage, soil evapotranspiration, and interflow. The calculation formulas are as follows:

[0238]

[0239]

[0240] in:

[0241] Indicates the flow in the soil (m) 3 ); This indicates the amount of water recharged to shallow groundwater (m³). 3 ); , These represent the soil moisture content (m³) at the beginning and end of the time period, respectively. 3 ); , These represent the outflow coefficient from the soil and the recharge coefficient for shallow groundwater, respectively. This indicates the water storage capacity (m³) during time period h. 3 );

[0242] Next, the groundwater runoff process was calculated. The calculations included both deep and shallow groundwater reservoirs, and both rapid and slow runoff were performed. The calculation formulas are as follows:

[0243]

[0244]

[0245]

[0246] In the formula: , These represent fast runoff and slow runoff, respectively (m 3 ); , These represent the shallow groundwater runoff coefficient and the deep groundwater runoff coefficient, respectively. , This indicates the water storage capacity (m³) of shallow and deep reservoirs over a given period. 3 ), , These represent the initial water storage capacity (m³) of shallow and deep reservoirs during the time period, respectively. 3 ); , These represent the artificial water extraction volumes (m³) of shallow and deep reservoirs, respectively. 3 ); , These represent the river and lake replenishment amounts (m³). 3 ); It is the shallow water infiltration coefficient.

[0247] In this scenario, the total natural water supply can be summed from the above production flows, Q. total,h = Q h ’ +Q h +Q x,h Q h ’ Q h Q x,h , which are the surface runoff, soil runoff and groundwater runoff for time period h, respectively;

[0248] The gap between total natural water supply and regional water demand is the water shortage for each industry, calculated using the following formula: Q n =Q need -Q total .

[0249] Then, based on the changes in water shortages from hydropower and water conservancy projects, and combined with the economic value of unit volume of industrial, agricultural, and domestic water use, the drought resistance and disaster reduction benefits of hydropower and water conservancy projects are estimated. The changes in water shortages for industry, agriculture, and domestic use in the basin under different drought scenarios before and after project construction are extrapolated and denoted as ΔQ. ng =Q ng，1 - Q ng，0 (Industrial water shortage), ΔQ nn =Q nn，1 -Q nn，0 (Agricultural water shortage), ΔQ ns =Q ns，1 - Q ns，0(Water shortage for domestic use) Among them, Q n，1 Q is the water shortage before the construction of water conservancy and hydropower projects. n，0 This is to address the water shortage following the construction of water conservancy and hydropower projects;

[0250] 3) Construction of Economic Evaluation Model: Based on the economic benefit indicators of the watershed's water-receiving area and the water demand during the same period, the unit economic benefits of water resources for industry, agriculture, and domestic use are calculated. The calculation formula is as follows:

[0251]

[0252] The formula considers three economic unit prices for industrial, agricultural, and domestic water use, with i=1, 2, and 3 respectively. Let i be the economic value per unit volume of water used in the i-th category. Let i be the water demand for water use category i, and GDP be the total economic output of the region. This represents the ratio of the total economic output of the industry corresponding to the i-th type of water use to the total economic output. Then, based on the changes in water shortage in each water-receiving area before and after the project construction, a specific return period (T) is calculated. B The calculation formula for the drought resistance and disaster reduction benefits of engineering projects in the following scenario is as follows:

[0253]

[0254] In the formula L B To improve the effectiveness of drought disaster prevention and mitigation, Let represent the change in water shortage for the corresponding industry under two operating conditions: before and after the completion of the water conservancy and hydropower project, representing the i-th type of water shortage. Let be the economic value of a unit volume of water used in the i-th category.

[0255] 4) Establishment of the probability density curve for drought disaster prevention and mitigation benefits: Based on the frequency of drought disaster occurrence and loss characteristic index data under the influence of meteorological conditions in different watersheds, an occurrence frequency (P) curve is established. B =1 / T B ) and the reduction in losses (L) B The correlation between P and P is fitted using standard exponential distribution, logarithmic distribution, normal distribution, Weibull distribution, and log-normal distribution, respectively. B —L B The curves are selected by taking the maximum values ​​of RMSE and R² as the distribution function with the highest consistency. A statistical distribution curve of the engineering drought resistance and disaster reduction benefits and its corresponding probability density function (f) are then constructed. B (L) B ), calculate the expected disaster reduction benefits

[0256] Step 6, Flood Disaster Mitigation Effect Analysis. Based on the HEC-RAS analysis model used in this invention, and socio-economic development, population, and infrastructure data, the flood evolution process and downstream inundation losses under natural flood conditions encountered by the project are clarified.

[0257] 1) Flood disaster analysis scenario formulation: Based on the rainstorm disaster event database and historical flood disaster characteristics constructed in step 2, and according to the beat frequency analysis results, different return periods (T) are selected. C Taking flood disasters (5, 10, 20, 50, 100, 500, 1000, 10000 years) as the analysis object, the rainfall in the scenario is defined, and the upstream flood peak flow and tributary flood peak flow parameters are determined through hydrological calculations;

[0258] 2) Flood Evolution Process Model Analysis: Using hydrological analysis models such as HEC-RAC, under the selected flood scenario with a return period, and with upstream peak discharge, regional topography, tributary peak discharge, upstream precipitation, and watershed topography as input boundary conditions, the evolution process of flood discharge is calculated to clarify the flood evolution curves before and after project construction, and the highest flood level H along the route. max The peak flow rate Q along the route, the staggered peak flow time of the main stream and tributaries, and the downstream flood inundation range;

[0259] 3) Calculation of flood disaster loss reduction: Based on the inundation range and flood inundation depth d obtained from flood evolution calculations. s Based on the number of disaster loss analysis reference indicators n determined in step 2 (item a), i Comparative analysis of the number n of reference objects damaged before and after the construction of the project. i The unit loss price p of the damaged objects within the geological disaster-affected area is determined based on reference to regional statistical yearbooks and extensive experience standards. i The disaster prevention and mitigation benefits are calculated according to the following formula:

[0260]

[0261] In the formula, ΔL represents the disaster prevention and mitigation benefits of the water conservancy and hydropower project, L1 represents the losses caused by disasters before project construction, L0 represents the losses caused by disasters after project construction, and p i Let n be the unit price of loss for the reference object of the i-th type of damage. i，1 d represents the amount of damage to a reference object before construction. s，1 H serves as the reference submersion depth before project construction. i n represents the total height of the reference object. i，0 d represents the amount of damage to the reference object after the project construction. s，0 The submersion depth is used as a reference for the project after construction; for infrastructure with a certain height, such as residential buildings and stations, the submersion depth is determined by the object height H. i and the submerged water depth d sThe ratio between these ratios is used to weight the calculation of actual damage to the object, thus improving the accuracy of the calculation.

[0262] 4) Establishment of the probability density curve for flood disaster prevention and mitigation benefits: Based on the loss characteristic index data caused by floods with different return periods, the probability density curve for flood disaster prevention and mitigation benefits is established using the return period (T) of the flood disaster. C Calculate the frequency of flood occurrence (P) according to steps 2) and 3). C =1 / T C ), and the corresponding reduction in losses caused by floods (L C ), forming P c ~L c The curve is obtained by fitting P with the standard exponential distribution, logarithmic distribution, normal distribution, Weibull distribution, and log-normal distribution, respectively. C —L C The curve is used to calculate the degree of agreement between the distribution function and the disaster evolution data. The distribution function with the highest RMSE and R² values ​​is selected as the distribution function with the highest degree of agreement. A statistical distribution curve of the engineering drought relief and disaster reduction benefits and its corresponding probability density function (f) are then constructed. C (L) C ), calculate the expected disaster reduction benefits

[0263]

[0264] Step 7: Coupling of multi-hazard integrated disaster reduction benefits.

[0265] The multi-hazard loss probability cumulative distribution model proposed in this invention calculates the comprehensive disaster prevention and mitigation effect of the project, considering that the three types of disasters occur randomly and are independent events, and that their respective probabilities of occurrence do not affect each other.

[0266] 1) Randomness Model Analysis

[0267] Expected benefits of multi-hazard integrated disaster reduction: Selecting the disaster recurrence period P d The disaster reduction benefits L for three types of disasters were randomly generated using a computer random number generation algorithm. n （i） Let n = A, B, C, i = 1, 2, 3...N, where N is the number of random samples. The goal is to calculate the disaster reduction benefit value L under the influence of the three randomly generated disasters. n （i） It follows the probability density function of the corresponding disaster reduction benefits. If the number of random samples N ≥ 10000, then the comprehensive disaster reduction benefits can be calculated according to the following formula.

[0268]

[0269] Based on the above formula, the expected value of the comprehensive disaster reduction benefit of the project, E(L), can be plotted. nThe relevant curves of the project operation period t were obtained, and the expected curve of the comprehensive disaster reduction benefits of water conservancy and hydropower projects in the face of three natural disasters was obtained, E=f(t).

[0270] Calculation of cumulative disaster reduction benefits of multi-hazard engineering: By integrating the function on the time scale, the cumulative disaster prevention and mitigation benefits of the project in different operating periods and the corresponding curves are obtained as follows.

[0271]

[0272] 2) Deterministic Model Analysis

[0273] The above describes the method for calculating the disaster prevention and mitigation effects of hydropower and water conservancy projects during different operating periods using a stochastic model. At the same time, it is necessary to draw on deterministic models to analyze the impact of projects on non-economic indicators.

[0274] Establish a non-economic indicator system: comprehensively consider the potential impacts of natural disasters on hydropower and water conservancy projects, and select population impact... Number of ecological protection zones Number of medical beds Number of primary and secondary school students Civil affairs agencies establish index A non-economic indicator evaluation system is formed.

[0275] Calculating disaster impact weights: Assuming the impacts of floods, droughts, and geological disasters on the population are as follows: , and These values ​​represent the population impact of each disaster type.

[0276] Calculate the total population That is, the total impact of all disaster types on this dimension:

[0277]

[0278] The formula for calculating the relative proportion of each disaster type in the population dimension is as follows:

[0279]

[0280] This formula indicates that the proportion of flood impact in the total population is the ratio of the population impact value of floods to the total population impact value of all disasters. The proportion of other disasters is calculated in the same way.

[0281] Similarly, similar calculations are performed for the other four indicators. For example, to calculate the number of ecological reserves, the total impact of ecological reserves needs to be calculated first:

[0282]

[0283] Next, the relative proportion of each type of disaster in the ecological protection zone dimension is calculated:

[0284]

[0285] Regarding the number of medical beds:

[0286]

[0287]

[0288] Regarding the number of primary and secondary school students:

[0289]

[0290]

[0291] Regarding the establishment index of civil affairs institutions:

[0292]

[0293]

[0294] After calculating the relative weight of each disaster in each indicator, these weights are combined to obtain the overall weight of each disaster. To ensure a reasonable allocation of weights for each disaster type in the overall impact, the overall weight of each disaster is calculated by taking the average of the weights of the five dimensions.

[0295] For example, the overall weight of floods The average value will be calculated based on its proportion across five dimensions: population, ecological protection zones, number of medical beds, primary and secondary school students, and civil affairs institutions.

[0296]

[0297] The formula for the combined weighting of drought and geological disasters is similar:

[0298]

[0299]

[0300] Since different types of disasters exhibit different characteristics across different dimensions, their final weight is a comprehensive reflection of the influence across five dimensions.

[0301] Quantitative analysis of the non-economic impact of disasters: Based on the above steps (4) to (7), calculate the reduction value ΔP of direct economic losses caused by geological disasters, droughts, and floods with different return periods, and select the reduction value ΔP of losses under the three most extreme natural disaster scenarios under the analyzed working conditions. flood ΔP geo ΔPdrought The quantitative formulas for analyzing the impact of each disaster on the above non-economic indicators are as follows:

[0302] ΔP total =ΔP flood +ΔP geo +ΔP drought

[0303]

[0304]

[0305]

[0306] In this invention, the economic evaluation model used in the analysis of the evolution law of geological disasters includes the disaster reduction benefits under normal working conditions and the disaster reduction benefits under extreme working conditions, respectively considering the disaster prevention and mitigation benefits of engineering in response to identified geological disaster points and extreme major chain disasters.

[0307] In this invention, the cumulative frequency variation characteristics of the disaster prevention and mitigation benefits of engineering in response to floods and droughts are respectively fitted by normal distribution and exponential distribution in the coupling of multi-hazard comprehensive disaster reduction benefits. From the perspective of probability distribution, the cumulative frequency curve of comprehensive disaster reduction benefits of engineering disaster prevention and mitigation benefits and disaster recurrence period is established, and a new quantitative analysis method for disaster loss prediction is proposed.

[0308] In this invention, the comprehensive disaster reduction benefit analysis of engineering projects with multiple hazards fully and comprehensively considers the impact of the project on socio-economic data development (administrative boundaries, population distribution, per capita / total GDP), population and infrastructure data (the number and distribution of farmland, airports, highways, railways, hospitals, schools, ecological protection areas and other important public infrastructure) after the project is completed. It proposes a brand-new economic and non-economic evaluation index system for comprehensively evaluating the disaster prevention and mitigation effects of water conservancy and hydropower projects.

[0309] In this invention, the comprehensive disaster reduction effect analysis of engineering projects with multiple hazards takes into account both the positive and negative effects generated after the construction of the project, and proposes a brand-new quantitative analysis and calculation method for disaster reduction benefits, as well as a qualitative analysis approach for the disaster prevention and mitigation effects of engineering projects.

[0310] Example 2:

[0311] 1) Select the natural disaster prevention targets and disaster loss targets of the project.

[0312] Taking a water conservancy project as an example, this paper analyzes and clarifies the natural disasters that the project is designed to prevent and the objects affected by these disasters. The analysis of natural disaster objects considers floods, geological disasters, and droughts in the watershed where the project is located. The analysis of the objects affected by the disasters needs to identify the population and other economic entities (including houses, roads, farmland, etc.) within the scope of the natural disaster's impact.

[0313] 2) Analyze the climate evolution patterns before and after the project construction.

[0314] Meteorological stations were selected for the project area and watershed, and historical meteorological and hydrological data were collected. Databases of rainstorm and drought disaster events were constructed, and the spatial and temporal characteristics of disasters were analyzed from the perspectives of disaster frequency, duration, and intensity to predict future disaster evolution patterns.

[0315] 3) Analyze the amount of geological disaster losses before and after the project construction.

[0316] A comprehensive identification method combining optical remote sensing and InSAR identification was used to identify potential geological hazard points in the reservoir area and near the dam. The geological hazard risk index was analyzed using geological hazard hazard, vulnerability and the number of disaster-bearing bodies as the main parameters to assess the degree of geological hazard risk.

[0317] Taking landslides, collapses, and debris flows as examples, and referring to the detailed investigation specifications for landslides, collapses, and debris flows, the geological hazard activity level is divided into four levels: "extremely high," "high," "medium," and "low" (Table 1) based on factors such as the geological hazard body's exposed conditions, the geological background of the hazard, the magnitude of deformation signs or deformation, and the degree of structural surface development. Simultaneously, based on the type, level, importance, and quantity of the geological hazard objects, the geological hazard severity is divided into four levels: "extremely high," "high," "medium," and "low" (Table 2). Based on the above qualitative evaluation, a qualitative assessment of individual geological hazard risks is conducted according to Table 3. Following the above process, the number of geological hazard points and the area of ​​risk zones in various locations are quantitatively analyzed in two scenarios: before and after the construction of water conservancy and hydropower projects.

[0318] Table 1 Classification of Geological Hazard Activity Levels

[0319]

[0320] Table 2 Classification of Geological Hazard Severity Levels

[0321]

[0322] Table 3 Qualitative Risk Assessment of Individual Geological Hazard Investigation Sites

[0323]

[0324] Meanwhile, the risk of landslides causing blockages in rivers and triggering chain disasters of landslide-dammed lakes was analyzed for major and extra-large landslides, and the reservoir capacity and flood flow of landslide-dammed lakes were determined.

[0325] In response to the impact of individual geological disasters and chain disasters, and with reference to the statistical yearbook of the project area and extensive experience standards, the economic calculation standards for various loss standards in the region were priced and calculated. The losses of houses, roads and bridges, population GDP and farmland due to geological disasters before and after the project construction were determined and uniformly converted into economic losses according to economic measurement standards.

[0326] 4) Analyze the drought losses before and after the project construction.

[0327] The disaster reduction benefits of the project in response to drought disasters are analyzed by taking the entire watershed where the project is located as the analysis object. A water resources projection and analysis model for the entire watershed is established, and scenarios of normal water year (50%), dry year (75%), extremely dry year (95%), and extreme drought (99%) are proposed. Based on the model projection, the water shortage of the watershed and the water replenishment of the project under each scenario are calculated. Water demand is divided into three parts: industrial, agricultural, and domestic water. Based on the statistical yearbook of the project area and extensive experience standards, the unit economic conversion of industrial, agricultural, and domestic water is determined, that is, the economic benefits that can be generated per cubic meter of water. The drought relief and disaster reduction benefits of the project are calculated as: water replenishment × unit economic benefits.

[0328] 5) Analyze the flood losses before and after the project construction.

[0329] The analysis of the impact and loss of floods consists of two parts: analysis of watershed inflow conditions and analysis of flood losses.

[0330] In the analysis of watershed inflow conditions, the upstream and downstream confluence of the small watershed where the project is located is first sorted out. Based on the historical data of the watershed hydrological station, the frequency of flood encounters is analyzed to clarify the proportion of upstream flood and downstream runoff, and to determine the main impact range of the project's flood interception on the downstream flood control capacity, so as to determine the scope of flood evolution analysis.

[0331] The flood loss analysis uses the HEC-RAS software to construct a flood evolution analysis model of the upstream and downstream areas of the project. Data layers such as regional topography, infrastructure, and population distribution are overlaid on the model to deduce the impact characteristics of the upstream 10, 50, 100, 200, 1000, and 10000-year standard floods on the downstream area under two scenarios before and after the project construction. The affected population, roads, bridges, farmland, and other facilities are identified. Based on the statistical yearbook of the project area and extensive experience standards, an economic transformation index of facility impact is constructed to determine the reduction in economic losses suffered by the downstream area after the project construction under 10- to 10000-year flood conditions, i.e., the flood control and disaster reduction effect of the project.

[0332] 6) Comprehensive disaster reduction benefit analysis during the project operation period

[0333] By integrating the reduction in regional economic losses that the project can reduce under different standard geological disaster, drought, and flood scenarios (Table 4), a disaster loss probability distribution function is constructed to clarify the quantitative correlation between the disaster reduction effect of the project on various disasters and the probability of disaster occurrence.

[0334] Table 4. Analysis Scenarios for Various Disasters

[0335]

[0336] After clarifying the independent disaster reduction loss probability distribution functions for various disasters, the Monte Carlo method is used to merge these independent disaster reduction loss probability distribution functions into a comprehensive engineering disaster reduction loss probability distribution function, such as... Figure 2 As shown. For the project's operational periods of 2 years, 5 years, 10 years, 20 years, and 100 years, the average annual disaster reduction benefit (i.e., the function mean) is calculated according to the probability distribution function of the comprehensive disaster reduction loss. A quantitative relationship is established between the project's operational period and the average annual disaster reduction benefit. A nonlinear fitting method is used to obtain the fitting curve of the project's expected average annual comprehensive disaster reduction benefit (EAL). Figure 3 Using the expected annual comprehensive disaster reduction benefit function of the project as the objective function, the integral values ​​for different project operation periods are calculated to obtain the cumulative comprehensive disaster prevention and mitigation benefit of the project within that operation period. The function curve is shown below. Figure 4 As shown.

[0337] This invention can evaluate and analyze the comprehensive disaster prevention and mitigation effects of hydropower projects in the face of various natural disasters at the watershed scale. It overcomes the problem that different natural disasters affect different objects, there are many indicators to characterize the disaster consequences, and it is difficult to quantify the disaster prevention and mitigation effects. It transforms the different economic and social impacts caused by various disasters into economic losses, providing reliable technical support for the economic benefits and necessity analysis of engineering construction.

[0338] Obviously, the present invention is not limited to the details of the above embodiments. The above embodiments should be considered exemplary, not restrictive. The scope of the invention is defined by the appended claims and includes all variations falling within the meaning and scope of equivalents of the claims. Any reference numerals in the claims should not be considered as limiting the scope of the claims.

[0339] Furthermore, this specification should be considered as a whole, and the above-described embodiments are not the only independent technical solutions of this invention. The technical solutions in the embodiments can be appropriately combined and adjusted to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for analyzing the comprehensive disaster prevention and mitigation effects of multiple hazards in water conservancy and hydropower projects, characterized in that, include: Step S1: Based on the geographical location of the water conservancy and hydropower project, the characteristics of the river basin, and the climate characteristics of the region, determine the various natural disasters to be analyzed and several reference objects for damage. Step S2: Analyze historical climate data of the areas affected by water conservancy and hydropower projects, and construct a model for each type of natural disaster. Corresponding typical disaster event database ; Step S3, Set natural disasters The recurrence sequence of disasters; for natural disasters Recurrence period of each disaster The corresponding disaster occurrence frequency was calculated. The frequency of the disaster is used. For the aforementioned typical disaster event database Analysis was conducted to obtain the frequency of the disaster as described. Various typical disaster events form typical disaster scenarios. ; Step S4, in each typical disaster scenario Simulations and simulations of typical disaster processes are conducted to obtain the disaster recurrence period. In the simulated scenario, the total loss caused by the disaster to each of the aforementioned damaged reference objects is the reduction in disaster loss compared to the total loss caused to each of the aforementioned damaged reference objects before the completion of the water conservancy and hydropower project. This represents the disaster reduction benefits of the project; This establishes the frequency of disaster occurrence. With disaster loss reduction value The correlation between them; Step S5: Analyze the frequency of various disasters. The obtained correlations are subjected to curve fitting to obtain a probability distribution curve of engineering disaster reduction benefits that characterizes the correlation between the frequency of each disaster and the engineering disaster reduction benefits, thereby constructing a system for dealing with each natural disaster. The probability density function of engineering disaster reduction benefits ; Step S6, based on the situation of each natural disaster The probability density function of engineering disaster reduction benefits To build the expected disaster reduction benefits ; Step S7, consider each type of natural disaster All are independent events that occur randomly. A stochastic model is used to study various natural disasters during different engineering operation periods t. Expected disaster reduction benefits A comprehensive analysis yielded the following project operation period: Expected comprehensive disaster reduction benefits ; Step S8, change the different engineering operation periods Repeat steps S4 to S7 to obtain the expected comprehensive disaster reduction benefits. ~Engineering Operation Period The relevant curves were analyzed to obtain the expected curve of comprehensive disaster reduction benefits; By selecting the target project operation period, the expected curve of the comprehensive disaster reduction benefits is analyzed to obtain the cumulative disaster reduction benefit value of the project during the target project operation period; In step S4, for geological disasters, the reduction value of disaster losses is... The calculation method is as follows: Step B1, the typical disaster scenario For earthquake-related geological hazards, based on typical disaster scenarios Based on the peak ground acceleration zoning map, determine the ground ground acceleration g at the location of the disaster point. A The stability coefficient of the unstable body under earthquake conditions at the corresponding disaster recurrence period was calculated using the circular arc sliding method. For unstable bodies with stability coefficients lower than the standard requirements, the landslide volume and elevation were estimated based on satellite remote sensing imagery, and the post-landslide depositional elevation H was also estimated. d =-355.73+65.011×g×V d Where g is the acceleration due to gravity, and V d To estimate the volume of the landslide; Step B2, based on the post-landslide accumulation elevation H d Assess the risk of the landslide dam breaking. If the risk of the landslide dam breaking is higher than the set threshold, proceed to step A3. Step B3: Calculate the reservoir capacity of the barrier lake formed by the landslide blocking the river. : =K1×S 坝 ×l y； Wherein: S 坝 The cross-sectional area of ​​the dam is estimated based on a triangular cross-section; y K1 represents the maximum backfilling length of the landslide dammed lake; K1 is the backfilling coefficient, and the greater the river slope, the smaller the value of K1. Step B4: Simulate the dam failure of the landslide dam. Multiple disaster points are selected at equal intervals between the floodwaters released after the dam failure and the downstream water conservancy and hydropower projects. At each disaster point, the distance from the dam is set to l. The maximum flow rate at the dam failure is calculated using the following formula. and flood peak height : ； ； in: For the reservoir capacity of the landslide dammed lake; The maximum flow rate at the dam site; This represents the maximum flow velocity of the flood. This is an empirical coefficient; The maximum water depth at which the dam breaks; A is the cross-sectional coefficient of the valley at the disaster point, A=F / H, where F is the cross-sectional area and H is the cross-sectional height; The riverbed shape index, The riverbed gradient; Step B5: Based on the maximum dam breakage flow rate at each disaster point. and flood peak height Based on topographic data, the ground elevation d0 at each disaster point is determined, and... x - d0 calculates the flood inundation range and inundation depth along the route from the landslide dam to the hydropower project. s ; Step B6: Based on the flood inundation range and depth along the route, extrapolate the actual damage reference objects and their number during the unstable body sliding and collapse process. The following formula is used to obtain the disaster loss reduction value. : ； in: The total losses caused by flood disasters to the reference object before the completion of water conservancy and hydropower projects; The total loss caused by flood disasters to the reference object after the completion of water conservancy and hydropower projects; This refers to the number of reference objects that caused actual damage during the sliding and collapse of unstable bodies before the completion of water conservancy and hydropower projects. For the first The unit price of loss for each damaged reference object. For the first The number of losses to each damaged reference object; For the first The submersion depth of a damaged reference object For the first The total height of each disruptive reference object; This refers to the number of reference objects that cause actual damage during the sliding and collapse of unstable bodies after the completion of water conservancy and hydropower projects. For the first The unit price of loss for each damaged reference object. For the first The number of losses to each damaged reference object; For the first The submersion depth of a damaged reference object For the first The total height of each disruptive reference object; In step S4, for drought disasters, the reduction value of disaster losses is... The calculation method is as follows: Step C1, the typical disaster scenario For typical drought disaster scenarios, a water resources extrapolation model considering the linkage of water conservancy and hydropower projects is constructed, using the basin rainfall, runoff, and water diversion volume of water conservancy and hydropower projects as boundary conditions. Step C2: Using the water resource projection model, obtain the total natural water supply Q for each time period h in the water resource projection cycle. total,h , where Q total,h = Q h ’ +Q h +Q x,h Q h ’ Q h Q x,h , which are the surface runoff, soil runoff and groundwater runoff for time period h, respectively; Step C3: At time h, obtain the regional water demand Q before the completion of the water conservancy and hydropower project. need,h,1 And the regional water demand Q after the completion of water conservancy and hydropower projects need,h,0 ; Step C4: Use the following formula to obtain the water shortage Q in the region before the completion of the water conservancy and hydropower project. h,1 And the water shortage Q in the region after the completion of water conservancy and hydropower projects h,0 ; Q h,0= Q need,h,0 - Q total,h Q h,1 =Q need,h,1 -Q total,h Step C5: Using the following formula, the reduction in regional water shortage ΔQ after the completion of the water conservancy and hydropower project is obtained. h,0 : ΔQ h,0 = Q h,1 -Q h,0 Step C6, using the following formula, is based on the reduction in regional water shortage ΔQ after the completion of the water conservancy and hydropower project. h,0 Using three economic evaluation models for industrial, agricultural, and domestic water resources, the economic benefits corresponding to the reduction in water shortage are obtained, and thus the reduction in disaster losses is derived. ; in = ; , , These represent the reduction in water shortages for agriculture, industry, and domestic use, respectively. , , The economic benefits per unit of water use are respectively for agriculture, industry, and domestic use; The water resources simulation model includes a surface runoff process simulation sub-model, an interflow runoff process simulation sub-model, and a groundwater runoff process simulation sub-model. The sub-model for extrapolating surface runoff processes is as follows: ； ； ； ； ； in: Surface runoff; impermeable area The resulting runoff; Effective water volume; Permeable area The resulting runoff; It is an over-permeable flow; To accumulate sufficient flow; To maximize infiltration capacity; This refers to the excess amount of infiltration runoff. This represents the maximum water storage capacity of the soil. This represents the initial water cut flow rate at time period h-1; This refers to precipitation. This refers to the amount of water added artificially; This represents the evapotranspiration conversion factor; Evaporation amount; This indicates the amount of water that can be stored during time period h. The sub-model for extrapolating the interflow process is as follows: The model converts soil water into four components: soil recharge to shallow groundwater, soil water storage, soil evapotranspiration, and interflow. The formulas are as follows: ； ； in: It indicates that the soil flows through the stream; This indicates the amount of water supplied to shallow groundwater. , These represent the soil moisture content at the beginning and end of the time period, respectively. , These represent the outflow coefficient from the soil and the recharge coefficient for shallow groundwater, respectively. This indicates the amount of water that can be stored during time period h. The sub-model for extrapolating the underground runoff process is as follows: It calculates both deep and shallow underground reservoirs, and performs calculations for rapid and slow runoff, using the following formulas: ； ； ； In the formula: , These represent fast runoff and slow runoff, respectively. , These represent the shallow groundwater runoff coefficient and the deep groundwater runoff coefficient, respectively. , This indicates the water storage capacity of shallow and deep reservoirs over a given period. , These represent the initial water storage of shallow and deep reservoirs during the time period, respectively. , These represent the artificial water extraction volumes from shallow and deep reservoirs, respectively. , These represent the replenishment amounts of rivers and lakes, respectively. It is the shallow water infiltration coefficient.

2. The method for analyzing the comprehensive disaster prevention and mitigation effects of water conservancy and hydropower projects according to claim 1, characterized in that, The natural disasters mentioned include floods, geological disasters, and droughts.

3. The method for analyzing the comprehensive disaster prevention and mitigation effects of multiple hazards in water conservancy and hydropower projects according to claim 1, characterized in that, In step S4, for flood disasters, the reduction value of disaster losses is... The calculation method is as follows: Step A1, Typical Disaster Scenario For flood disasters, based on typical disaster scenarios The precipitation, peak flow, and process curves of the upstream basin were determined. Combined with the topography of the upstream and downstream basins, a hydrological analysis model was used to extrapolate the flood evolution curves before and after the completion of the hydropower project, and the highest flood level H along the route was determined. max The peak flow rate Q along the route and the staggered peak flow times of the main stream and tributaries are used to determine the flood inundation range and depth along the route. Step A2: Based on the flood inundation range and depth along the course, extrapolate the actual damage reference objects and the number of damage reference objects that will cause damage during the flood disaster. Step A3: Use the following formula to obtain the reduction value of disaster losses. : ； in: The total loss caused by flood disasters to the reference object after the completion of water conservancy and hydropower projects; The total loss caused by flood disasters to the reference object after the completion of water conservancy and hydropower projects; This refers to the number of reference objects that caused actual damage during the sliding and collapse of unstable bodies before the completion of water conservancy and hydropower projects. For the first The unit price of loss for each damaged reference object. For the first The number of losses to each damaged reference object; For the first The submersion depth of a damaged reference object For the first The total height of each disruptive reference object; This refers to the number of reference objects that cause actual damage during the sliding and collapse of unstable bodies after the completion of water conservancy and hydropower projects. For the first The unit price of loss for each damaged reference object. For the first The number of losses to each damaged reference object; For the first The submersion depth of a damaged reference object For the first The total height of the reference object that was destroyed.

4. The method for analyzing the comprehensive disaster prevention and mitigation effects of water conservancy and hydropower projects according to claim 1, characterized in that, In step S6, the expected disaster reduction benefits are obtained using the following formula. : ； in: and These are: natural disasters The minimum and maximum values ​​of disaster loss reduction obtained during all disaster recurrence periods.

5. The method for analyzing the comprehensive disaster prevention and mitigation effects of multiple hazards in water conservancy and hydropower projects according to claim 1, characterized in that, Step S7 is as follows: Selecting the recurrence period of the disaster In the probability density function of disaster reduction benefits in engineering Under the constraints, a random number generation algorithm is used to randomly generate each type of natural disaster. Disaster reduction benefit value ,in, The number of random samples; The expected comprehensive disaster reduction benefits can be obtained through the following formula. : ； in: Types of natural disasters; Simulating different project operation periods t, we obtain the expected comprehensive disaster reduction benefits corresponding to different project operation periods t. Thus, the correlation curve between the expected value of comprehensive disaster reduction benefits E(t) and the project operation period t is plotted, and the expected curve of comprehensive disaster reduction benefits E=f(t) of water conservancy and hydropower projects in the face of various natural disasters is obtained.

6. The method for analyzing the comprehensive disaster prevention and mitigation effects of water conservancy and hydropower projects according to claim 1, characterized in that, The cumulative disaster reduction benefit value of the project during its operation period is obtained using the following formula: The cumulative disaster reduction benefit value of the project during its operation period ; in: For the target project operation period; The expected comprehensive disaster reduction benefits are expressed as a curve function of the project's operating period t.

7. A comprehensive disaster prevention and mitigation effect analysis model for water conservancy and hydropower projects, characterized in that, The method for analyzing the comprehensive disaster prevention and mitigation effects of water conservancy and hydropower projects under multiple hazards, as described in any one of claims 1-6, includes: The typical disaster event database construction module is used to determine various natural disasters to be analyzed and several damage reference objects based on the geographical location of water conservancy and hydropower projects, the characteristics of their watersheds, and the climate characteristics of the region; it analyzes historical climate data of the areas affected by water conservancy and hydropower projects to construct a database for each type of natural disaster. Corresponding typical disaster event database ; Typical disaster scenario construction module, used to set up natural disasters The recurrence sequence of disasters; for natural disasters Recurrence period of each disaster The corresponding disaster occurrence frequency was calculated. The frequency of the disaster is used. For the aforementioned typical disaster event database Analysis was conducted to obtain the frequency of the disaster as described. Various typical disaster events form typical disaster scenarios. ; The typical disaster process simulation module is used to simulate and extrapolate various typical disaster scenarios. Simulations and simulations of typical disaster processes are conducted to obtain the disaster recurrence period. In the simulated scenario, the total loss caused by the disaster to each of the aforementioned damaged reference objects is the reduction in disaster loss compared to the total loss caused to each of the aforementioned damaged reference objects before the completion of the water conservancy and hydropower project. This represents the disaster reduction benefits of engineering projects; from this, the frequency of disaster occurrence can be established. With disaster loss reduction value The correlation between them; The module for constructing the probability density function of disaster reduction benefits in engineering projects is used to analyze the frequency of various disasters. The obtained correlations are subjected to curve fitting to obtain a probability distribution curve of engineering disaster reduction benefits that characterizes the correlation between the frequency of each disaster and the engineering disaster reduction benefits, thereby constructing a system for dealing with each natural disaster. The probability density function of engineering disaster reduction benefits ; The disaster reduction benefit expectation building module is used to build upon the expected benefits of each type of natural disaster. The probability density function of engineering disaster reduction benefits To build the expected disaster reduction benefits ; The comprehensive disaster reduction benefit expectation building module is used to consider each type of natural disaster. All are independent events that occur randomly. A stochastic model is used to study various natural disasters during different engineering operation periods t. Expected disaster reduction benefits A comprehensive analysis yielded the following project operation period: Expected comprehensive disaster reduction benefits ; The module for constructing the expected curve of comprehensive disaster reduction benefits is used to modify the operation phase of different projects. Repeat steps S4 to S7 to obtain the expected comprehensive disaster reduction benefits. ~Engineering Operation Period The relevant curves are analyzed to obtain the expected curve of comprehensive disaster reduction benefits; the operation period of the target project is selected, and the expected curve of comprehensive disaster reduction benefits is analyzed to obtain the cumulative disaster reduction benefit value of the project during the operation period of the target project.

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