A dynamic risk assessment method of green tide disaster based on event chain

Abstract

In view of the problems in the existing technology, in view of the current green tide emergency event level determination, which does not comprehensively consider the disaster-causing hazard of green tide disasters, the vulnerability of typical disaster-bearing bodies, the emergency response capacity and the risk of secondary events caused by green tides, according to the disaster-causing mechanism of green tide disasters and based on the "triangle" theory of public safety emergency management, the transmission and loss amplification effects of the event chain are comprehensively considered, and the green tide event chain is dynamically constructed. With the disaster-bearing body as the core, the dynamic risks of the green tide to disaster-bearing bodies of typical industrial types such as fisheries, tourism, nuclear power and important activity areas in a short period of time are calculated respectively. Finally, the overall risk level of the current event is comprehensively determined according to the risk degree of each disaster-bearing body.

Description

Technical Field

[0001] The present invention relates to the technical field of disaster risk assessment, and in particular to an event chain-oriented green tide disaster dynamic risk assessment method. Background Art

[0002] Green tide is a harmful algal bloom that occurs frequently worldwide and can cause serious damage to the coastal environment. Under specific environmental conditions, some large green algae in the seawater float after breaking away from the anchorage, and explosively proliferate or highly aggregate, causing water discoloration. The main causative species of green tide outbreaks are mostly Ulva and Enteromorpha of the Ulvaceae family of the Chlorophyta. In recent years, the Enteromorpha green tide disaster in the Yellow Sea of ​​my country has basically occurred regularly from April to the end of August every year, lasting for 5 months. It can be seen that the overall development of the disaster has the characteristics of slow change. However, affected by the growth cycle and drift speed, the impact of green tide disasters on nearshore disaster-bearing bodies is sudden and continuous. The disaster-causing bodies mainly include landscape destruction caused by large biomass, equipment damage, and environmental pollution, biological poisoning and public opinion events caused by rotten green tides. Secondary / derivative events of green tide disasters.

[0003] Chinese patent document CN201811202114.9 discloses a green tide disaster early warning system based on ecological model and its use method. The system includes three parts: green tide information database, visual forecast system and sensitive area early warning system. The green tide information database includes automatic inversion module and manual input module, which mainly download and store the location, time and coverage area of ​​the initial green tide; the visual forecast system includes system management module, typical ecological model information module, forecast module and green tide ecological model knowledge module; the sensitive area early warning system includes data graphic analyzer module and early warning module, which has functions such as data analysis, drawing and sensitive area early warning indication, and can be perfectly combined with the visual forecast system. The data used by the system are mainly the location, time and coverage of the green tide.

[0004] Zhou Jian et al., A Preliminary Study on the Economic Loss Assessment Model of Enteromorpha Green Tide Disaster, Journal of Natural Disasters, proposed the disaster chain of Enteromorpha Green Tide Disaster, and then took business application as the starting point and destination, initially constructed an indicator system for economic loss assessment of Enteromorpha Green Tide Disaster, and explored the establishment of an economic loss assessment model for Enteromorpha Green Tide Disaster for aquaculture losses, tourism losses, opportunity cost losses and ecological losses. This model has a good analysis of the disaster chain of green tide disasters, and provides loss indicators and corresponding components of indicators. However, this model focuses on loss assessment, and the corresponding components of indicators are mainly loss or cost indicators. The total loss is the sum of all losses, and does not involve indicator weights, so it cannot be used for ex ante risk warning and prevention and control.

[0005] Lin Yufei et al., Construction of Loss Investigation and Assessment Methods for Enteromorpha Green Tide Disaster, Journal of Natural Disasters, draws on the loss assessment methods and ideas related to natural disasters, based on the impact objects of Enteromorpha Green Tide, and takes scientificity, comprehensiveness, feasibility and practicality as the principles, constructing loss investigation and assessment methods from the aspects of marine aquaculture, coastal tourism, maritime transportation, industrial drainage, disaster emergency management and marine ecological impact. This method also focuses on the calculation of loss assessment, and does not involve indicator weights, and cannot be used for pre-risk warning and prevention and control.

[0006] Zhou Gang et al., Assessment of the impact of the green tide disaster of Enteromorpha in Qingdao on the non-use value of coastal tourism resources based on a binary questionnaire, Marine Environmental Science, used a binary empirical questionnaire in CVM to investigate the impact of the green tide disaster of Enteromorpha on the non-use value of Qingdao's coastal tourism resources, and investigated the willingness of tourists to pay for improving the coastal landscape during the period of the green tide of Enteromorpha. The impact of the green tide disaster of Enteromorpha on the non-use value of Qingdao's coastal tourism resources was monetized and evaluated through a binary selection model. This method uses a binary selection model for calculation, but the parameters are obtained based on the questionnaire, which has poor objectivity.

[0007] It can be seen that although there are some studies on loss assessment of green tide disasters, the assessment is simple and is generally only calculated based on the green tide coverage area and distribution area without comprehensive consideration. The indicators involved are not comprehensive and there is no weight distinction, let alone the judgment of the dynamic risk level of green tide disasters. Summary of the invention

[0008] In view of the problems in the prior art, in view of the fact that the current green tide emergency event level determination does not comprehensively consider the disaster-causing hazard of green tide disasters, the vulnerability of typical disaster-bearing bodies, the emergency response capacity and the risks of secondary / derivative events caused by green tides, the present invention is based on the disaster-causing mechanism of green tide disasters and the "triangle" theory of public safety emergency management, comprehensively considers the transmission and loss amplification effects of event chains, dynamically constructs a green tide event chain, and takes the disaster-bearing body as the core to calculate the risks of green tides to disaster-bearing bodies of typical industrial types such as fisheries, tourism, nuclear power and important activity areas. Finally, the risks of all disaster-bearing bodies are comprehensively determined to determine the risk level of the current green tide disaster event.

[0009] The present invention first provides an event chain-oriented green tide disaster dynamic risk assessment model, the assessment process of which includes:

[0010] Step 1: Delineate a third-level or fourth-level buffer zone with the disaster-prone body as the center, and construct a dynamic event chain using a chain effect analysis model based on the green tide disaster monitoring range, prediction range, and the disaster-prone body and its secondary / derivative event list within the intersection range with the buffer zone;

[0011] Step 2: Grid the entire sea area including the green tide disaster monitoring range, prediction range and the potentially affected area where the disaster-prone body is located, and conduct vulnerability assessment of the disaster-prone body based on the grid;

[0012] Step 3: Based on the quantitative evaluation method of green tide disaster hazard and green tide disaster emergency response capability indicators, obtain the hazard value and emergency response capability evaluation value of green tide disaster to different disaster-bearing bodies;

[0013] Step 4: Divide the grids based on the vulnerability of the disaster-bearing body, use the analytic hierarchy process (AHP), and apply the overall calculation formula of hazard*vulnerability / emergency capacity to conduct dynamic risk assessment on the secondary node events of the event chain that may be caused by green tide disasters within each grid, including industrial economic loss events in fisheries, tourism, nuclear power, protected areas, and important activity areas;

[0014] The calculation formula is as follows:

[0015] M1=(H d +H b +H e ) / 3

[0016]

[0017] In the formula, r i is the dynamic risk index of green tide disaster to the i-th sea area grid, ranging from 0 to 10;

[0018] M1 is the risk index of green tide disaster to current environment-related targets, ranging from 0 to 10;

[0019] H d is the disaster risk index, ranging from 0 to 10;

[0020] H b is the buffer zone hazard index, ranging from 0 to 10;

[0021] H e is the sea condition danger index, ranging from 0 to 10;

[0022] is the disaster index value;

[0023] is the weight of disaster indicators, which include green tide disaster level, historically prone areas, and the closest distance between green tide and disaster-bearing body;

[0024] a is the sequence number of the warning buffer, representing the relevant attributes of the a-th warning buffer;

[0025] b is the bth risk indicator element of the ath warning buffer zone;

[0026] W ab is the risk index weight value of the bth risk index element in the ath warning buffer zone;

[0027] X ab is the risk index value of the bth risk index element in the ath warning buffer zone;

[0028] is the sea condition index value,

[0029] is the weight of sea condition indicators, which include water temperature, wind speed and salinity;

[0030] M2 i is the vulnerability index of the ith grid, ranging from 0 to 10;

[0031] k is the kth vulnerability indicator element in the vulnerability indicator system;

[0032] W k is the weight value of the kth vulnerability indicator element;

[0033] F k is the vulnerability index value of the kth vulnerability index element;

[0034] M3 is the comprehensive evaluation index of emergency response capability, ranging from 0 to 10;

[0035] Step 5: When the green tide disaster divides the entire sea area into grids, each disaster-prone body contains multiple vulnerability assessment grids. The following takes a single disaster-prone body as the assessment object and calculates the dynamic risk of the green tide to the single disaster-prone body;

[0036] The calculation formula is as follows:

[0037]

[0038] Where n is the number of vulnerability assessment grids contained in the hazard-bearing body;

[0039] C j is the disaster risk index of the jth disaster-prone body, ranging from 0 to 10;

[0040] r i is the risk index of the ith vulnerability assessment grid, ranging from 0 to 10;

[0041] Step 6: According to the green tide dynamic risk assessment formula and value range in step 5, the dynamic risk level of the green tide disaster event to the disaster-bearing body is divided into 4 levels (extremely high risk, high risk, medium risk, and low risk), and the risk colors are marked as red, orange, yellow, and blue respectively. The risk level classification and color identification are shown in Table 1a; the dynamic risk assessment results are intuitively presented on the nautical chart in the form of a thematic map;

[0042] Table 1a Green tide disaster dynamic risk level evaluation table

[0043] Risk Level Very high risk High risk Lower risk Low risk Risk value area (8,10] (5,8] (2,5] (1,2]

[0044] Step 7: Calculate the disaster risk index of green tide disaster for all disaster-bearing bodies and comprehensively evaluate the overall risk level of green tide disaster. The calculation formula is as follows:

[0045]

[0046] In the formula, R g It is the overall risk level of green tide disaster.

[0047] Furthermore, the assessment model also includes step 8, according to the calculation formula and value range of the comprehensive risk index of the green tide disaster event in step 7, the comprehensive risk level of the green tide disaster event is divided into 4 levels (extremely serious, serious, relatively large, and general). The risk level classification and color identification are shown in Table 1b.

[0048] Table 1b Comprehensive risk level evaluation table of green tide disaster

[0049] Risk Level Level I (Extremely Major) Level II (major) Grade III (larger) Level IV (general) Risk value area (8,10] (6,8] (4,6] (2,4]

[0050] Furthermore, in step 1, a chain effect analysis model is used to construct a dynamic event chain, and the subordinate nodes of the green tide event in the event chain, including fishery disasters, tourism disasters, nuclear power disasters, protected area disasters, and important activity area disasters, are selected for further analysis.

[0051] Furthermore, the green tide disaster risk assessment index system in step 3 includes disaster indicators, warning buffer zone indicators, and sea condition indicators.

[0052] Furthermore, the disaster indicators include the green tide disaster level, historically prone areas, and the closest distance between the green tide and the disaster-sustaining body.

[0053] Furthermore, the early warning buffer zone indicators include green tide monitoring coverage rate, green tide forecast coverage rate, and green tide coverage duration in the core area.

[0054] Furthermore, the sea condition indicators include water temperature, wind speed and salinity.

[0055] Furthermore, the information data of the indicators adopts the information data released by the Ministry of Natural Resources.

[0056] Furthermore, the output results of the model mainly include green tide disaster hazard score, hazard distribution map, disaster-bearing body vulnerability distribution map, green tide dynamic risk distribution map and green tide comprehensive risk level.

[0057] The assessment model of the present invention is suitable for the dynamic risk assessment of green tide disasters. It assesses the risk level and size of green tides to important disaster-prone objects. On the basis of the assessment of the hazard of green tide disasters, the vulnerability of disaster-prone objects, and the emergency response capabilities, it can assess the dynamic risk and comprehensive risk level of green tides. Ultimately, it can output the disaster risk assessment value of the disaster-prone object caused by the current green tide disaster and the comprehensive risk level of regional green tide disasters.

[0058] Furthermore, for the green tide disaster risk assessment, such as Figure 2 As shown, it includes disaster risk assessment, early warning buffer zone assessment and sea condition assessment.

[0059] Furthermore, the disaster risk assessment method includes

[0060] (1) Determination of the disaster risk factor set

[0061] The factor set is a collection of all factors that affect the evaluation object. The first-level evaluation factor set of disaster risk is U = {real-time disaster situation U1, historical disaster situation U2}, and the second-level factor set is U1 = {disaster level U 11 , the closest distance to the disaster-affected body U 12}, U2 = {historical prone area U 21}.

[0062] (2) Principles of disaster level risk assessment For the green tide disaster level, the Beihai Bureau of the Ministry of Natural Resources’ “Green Tide Disaster Emergency Implementation Plan” is used. The principles for disaster level classification are shown in Table 1c, Green Tide Disaster Level Index Evaluation Table.

[0063] Table 1c Green tide disaster level index evaluation table

[0064]

[0065]

[0066] (3) Principle of risk assessment based on the closest distance between green tide and hazard-prone body

[0067] For the closest distance between the green tide and the disaster-prone body, the hazard assessment principle is based on the closest distance of 100 km between the green tide and the disaster-prone body. The index value increases linearly with decreasing distance. The specific formula is as follows:

[0068]

[0069] In the formula, Bl represents the risk index score of the distance between the green tide and the disaster-prone body; x represents the shortest distance between the green tide and the disaster-prone body.

[0070] (4) Principles of risk assessment for historically prone areas

[0071] For areas historically prone to green tide disasters, an evaluation is conducted based on the number of years in which green tide disasters have occurred in the past 10 years. The evaluation principles are shown in Table 2: Evaluation Table for Areas Prone to Green Tide Disasters.

[0072] Table 2 Evaluation table of historically prone areas of green tide disasters

[0073] Historically prone areas Scoring criteria Points Highly susceptible areas 9-10 times 8 High risk area 6-8 times 6 Lower risk area 3-5 times 4 Low risk area 1-2 times 2 Non-prone areas 0 times 0

[0074] Furthermore, the risk assessment of the early warning buffer zone indicators for the hazard-prone body includes the following steps:

[0075] Step 1: The overall evaluation factor set of the risk of the early warning buffer zone is

[0076] U3={monitoring coverage U 31 , forecast coverage U 32 , the green tide coverage duration in the core area U 33}.

[0077] Step 2: Divide the warning buffer zones for different industry types, as shown in Tables 3, 4, and 5.

[0078] Table 3. Setting of early warning buffer zones for fisheries and tourism

[0079] Buffer settings Buffer time The closest distance to the disaster-affected body (km) Core Area 2 days <20km Salvage Area 4 days ≥20km and <40km Warning area 7 days ≥40km and <70km

[0080] Table 4: Setting of early warning buffer zones in protected areas and nuclear power areas

[0081] Buffer settings Buffer time Distance to disaster-prone body (km) Core Area 2 days <20km Salvage Area 4 days ≥20km and <40km Warning area 7 days ≥40km and <70km Front warning area 10 days ≥70km and <100km

[0082] Table 5. Setting of warning buffer zones in important activity areas

[0083] Buffer settings Buffer time Distance to disaster-prone body (km) Core Area 5 days <50km Salvage Area 10 days ≥50km and <100km Warning area 15 days ≥100km and <150km Front warning area 20 days ≥150km and <200km

[0084] Step 3: Calculate the green tide forecast coverage and evaluate based on the forecast coverage

[0085]

[0086] In the formula, C cf It refers to the green tide forecast coverage rate in the core area; S pf It refers to the distribution area of ​​the overall distribution area of ​​the green tide after 72-hour drift prediction and the distribution area in the current core area obtained by superimposing the buffer zone; S c Refers to the area of ​​the current core area.

[0087] The evaluation of green tide forecast coverage in specific fisheries, tourism, protected areas, nuclear power areas and important activity areas is shown in Tables 6 and 7.

[0088] Table 6 Evaluation table of green tide forecast coverage index for fisheries and tourism

[0089] Core area coverage Salvage area coverage Warning area coverage Points 5％～10％ 10％～15％ 15％～20％ 2 10％～15％ 15％～25％ 20％～30％ 4 >15％ >25％ >30％ 6

[0090] Table 7 Evaluation table of green tide forecast coverage index for protected areas, nuclear power areas and important activity areas

[0091] Core area coverage Salvage area coverage Warning area coverage Front warning area coverage Points 5％～10％ 10％～15％ 15％～20％ 20％～25％ 2.5 10％～15％ 15％～25％ 20％～30％ 25％～40％ 5 15％～25％ 25％～35％ 30％～45％ 40％～55％ 7.5 >25％ >35％ >45％ >55％ 10

[0092] Step 4: Calculate the green tide monitoring coverage and evaluate based on the monitoring coverage

[0093]

[0094] In the formula, C cm It refers to the green tide monitoring coverage rate in the core area; S pm It refers to the green tide coverage area of ​​the current core area obtained by superimposing the green tide monitoring vector layer and the buffer zone; S c Refers to the area of ​​the current core area.

[0095] The evaluation of green tide monitoring coverage in specific fisheries, tourism, protected areas, nuclear power areas and important activity areas are shown in Tables 8 and 9.

[0096] Table 8 Evaluation table of fishery and tourism monitoring coverage index

[0097] Core Area Salvage Area Warning area Points 1％～2％ 2％～3％ 3％～5％ 2 2％～3％ 3％～5％ 5％～7％ 4 >3％ >5％ >7％ 6

[0098] Table 9 Evaluation table of monitoring coverage index for protected areas, nuclear power areas and important activity areas

[0099] Core Area Salvage Area Warning area Front warning area Points 1％～2％ 2％～3％ 3％～5％ 5％～7％ 2.5 2％～3％ 3％～5％ 5％～7％ 7％～10％ 5 3％～5％ 5％～7％ 7％～10％ 10％～15％ 7.5 >5％ >7％ >10％ >15％ 10

[0100] Step 5, according to the analysis of the disaster-causing process of green tide on aquaculture and tourism, whether green tide causes disaster has a lot to do with the amount of green tide biomass around the disaster-bearing body. On the one hand, the field survey shows that a large amount of green tide drifting to a position 1km away from the aquaculture area will have an impact on the aquaculture organisms. On the other hand, some of the aggregated green tides floating on the sea surface can be monitored by remote sensing means, but in addition, some floating green tides with smaller biomass and green tides that sink to the seabed due to rising temperatures cannot be monitored in time, and these green tides will also be washed into the aquaculture pond by tides and waves. At the same time, because the green tide will drift on the sea surface with wind and current, the green tide that is not monitored in the current disaster-bearing body sea area may have just passed through the disaster-bearing body sea area 1 hour ago.

[0101] According to the above reasoning, the green tide coverage duration in the core area within the last 10 days is selected as one of the green tide disaster risk factors rather than the green tide coverage duration in the disaster-bearing sea area. According to the disaster-causing relationship of green tide to related industries, the following green tide coverage duration risk function of the core area is constructed:

[0102]

[0103] Among them, x represents the coverage time of green tide in the core area, D t Represents the green tide hazard index value caused by the green tide coverage duration in the core area.

[0104] According to the above formula, the core area coverage time hazard function graph is as follows Figure 3 As shown, the horizontal axis is the number of days the core area is covered by green tide, and the vertical axis is the danger index value of the core area coverage duration.

[0105] Furthermore, the sea condition hazard assessment method includes

[0106] (1) Determination of the set of sea condition risk factors

[0107] The first-level evaluation factor set of sea condition danger is U = {growth factor U4, drift factor U5}, and the second-level factor set is U4 = {water temperature U 41 , Salinity U 42}, U5={wind speed U 51}.

[0108] (2) Principles of water temperature hazard assessment

[0109] The outbreak of green tide disasters depends to a large extent on the water temperature of seawater. The adaptability range of green tide to seawater is 10-30℃, and the optimal range is 15-25℃. Too high or too low temperatures will inhibit the growth of green tide algae.

[0110] According to existing research, the oceans covered by the 20-25℃ isotherm are where green tides grow rapidly. When the water temperature is between 20-25℃, as long as the nutrients and light are appropriate, green tides can grow wildly. Research shows that green tide algae reach their maximum growth at 25℃.

[0111] According to the growth and change law of Enteromorpha green tide with temperature, the following temperature hazard function is constructed:

[0112]

[0113] In the formula, x represents water temperature; D sst Indicated by the water temperature hazard index value.

[0114] The water temperature hazard function graph is as follows Figure 4 As shown in the water temperature danger function diagram, the horizontal axis is the water temperature (℃) and the vertical axis is the water temperature danger index value.

[0115] (2) Principles of salinity hazard assessment

[0116] The concentration of organic matter and nutrients in the water will affect the growth and reproduction of green tide algae such as Enteromorpha, which is a kind of eutrophic algae. Compared with temperature, the effect of salinity on the growth state of green tide is not obvious. The adaptation range of green tide to seawater salinity is 7.2-53.5, and the optimal range is 20.2-26.9. Under high salinity (20-32), the growth rate of green tide is the largest at 20℃, and under low salinity, the growth rate of green tide is the largest at 23℃-26℃. The maximum growth of green tide is achieved under the condition of salinity of 24. In the eutrophic water environment, the growth of green tide needs to consume a large amount of N and P nutrients in the water, and the growth rate reaches the maximum when N:P is 10:1.

[0117] According to the growth and change law of green tide with salinity, the following salinity hazard function is constructed:

[0118]

[0119] In the formula, x represents salinity; D s Indicated by salinity hazard index value.

[0120] According to the above formula, the salinity hazard function graph is as follows Figure 5 As shown in the salinity hazard function diagram, the horizontal axis is salinity, and the vertical axis is the green tide disaster hazard index value affected by salinity.

[0121] (3) Wind speed hazard assessment principles

[0122] The green tide floating on the sea surface drifts and gathers under the combined action of surface currents and wind. Its drift path is basically located in the angle between the sea surface wind and the sea surface circulation direction. According to the analysis of remote sensing data, wind is the main forcing force for the movement of green tide in the ocean. Its drift speed is mainly affected by the sea surface wind. There are two main ways for the wind field to affect the drift of green tide: the wind field directly drags the green tide; the wind field acts on the sea water to generate wind-induced currents, and then affects the drift of green tide through the flow field. Existing studies have shown that wind contributes half of the drift distance of green tide, and the correlation coefficient between the drift speed of green tide and the sea surface wind speed is 0.74. The onshore and offshore movement of green tide has a good correspondence with the rising and falling tides at the corresponding time.

[0123] According to the wind force level table and the correlation between the green tide drift speed and the sea surface wind speed, the following wind speed hazard function is constructed:

[0124] D w =10-10e -x / 15 ,x≥0

[0125] Where x represents the sea surface wind speed; D wIndicates the green tide disaster risk index value affected by wind speed.

[0126] According to the above formula, the wind speed hazard function graph is as follows Figure 6 As shown in the wind speed hazard function diagram, the horizontal axis is the sea surface wind speed (m / s) and the vertical axis is the hazard.

[0127] Furthermore, according to the green tide disaster risk assessment index system, five types of weights are set for the green tide disaster risk index weights: green tide disaster index weights, buffer zone risk index weights, fishery and tourism three-level buffer zone risk index weights, and protection zone, nuclear power zone and important activity zone four-level buffer zone risk index weights, as shown in Tables 10 to 14, where λ max represents the maximum eigenvalue, CI is the consistency index, and CR is the random consistency ratio.

[0128] Table 10 Calculation of weights of green tide disaster indicators

[0129]

[0130] Table 11 Calculation of weights of risk indicators in early warning buffer zones

[0131]

[0132] Table 12 Calculation of risk index weights for the third-level warning buffer zone for fisheries and tourism

[0133]

[0134] Table 13 Calculation of risk index weights for early warning buffer zones in protected areas, nuclear power areas and important activity areas

[0135]

[0136] Table 14 Calculation of sea condition index weights

[0137]

[0138] Furthermore, the overall evaluation of green tide disaster risk is carried out according to the following formula:

[0139] M1=(H d +H b +H e ) / 3

[0140] Where, M1 is the risk index of green tide disaster to current environmentally sensitive targets, with a value range of 0-10;

[0141] H d ——Disaster risk index, ranging from 0 to 10;

[0142] Hb ——Buffer zone hazard index, ranging from 0 to 10;

[0143] H e ——Sea condition danger index, ranging from 0 to 10;

[0144] In the above formula, H b The calculation includes three parts: disaster risk assessment, graded warning buffer zone risk assessment and sea condition risk assessment. The graded warning buffer zone risk assessment is divided into three types according to the risk of green tide disasters to different industrial economic types and the conclusions of event chain consequence analysis: risk assessment of green tide disasters to fisheries and tourism, risk assessment of green tide disasters to nuclear power and protected areas, and risk assessment of green tide disasters to important activity areas.

[0145] (1) Assessment of the risk of green tide disasters to fisheries and tourism

[0146] H b =α×Dm+β×Df+γ×Dc

[0147]

[0148] (2) Assessment of the risk of green tide disasters to nuclear power plants and protected areas

[0149] H b =α×Dm+β×Df+γ×Dc

[0150]

[0151] (3) Assessment of the risk of green tide disasters to important activity areas

[0152] H b =α×Dm+β×Df

[0153]

[0154] In the above formula, H b represents the danger level of the graded buffer zone, Dm, Df, and Dc represent the monitoring coverage rate, forecast coverage rate, and core area green tide coverage duration index values, respectively, and α, β, and γ represent their index weights, respectively. i , Df i They represent the graded index values ​​of monitoring coverage and graded forecast coverage of the i-th level warning buffer zone, respectively. According to the early warning buffer zone division method, fishery and tourism are divided into three-level buffer zones, corresponding to three types of monitoring coverage and forecast coverage, respectively. Nuclear power and protected areas as well as important activities are divided into four-level buffer zones, corresponding to four types of monitoring coverage and forecast coverage, respectively. i 、Wf iThey correspond to the monitoring coverage grading index weights and the forecast coverage index weights respectively.

[0155] Compared with the green tide disaster hazard assessment method, the disaster-prone body vulnerability assessment method takes into account the green tide sensitive attributes of the disaster-prone body and the sea area where it is located, and realizes regional comprehensive vulnerability assessment based on hierarchical analysis and GIS dynamic grid division technology.

[0156] The evaluation system takes natural areas as the evaluation object, and screens the sensitive attributes of the hazard-bearing body and analyzes the regional vulnerability based on the actual situation of the natural attributes, social and cultural values, management needs and green tide event chain of the sea area. Due to the large differences in the types of green tide hazard-bearing bodies, in order to improve the feasibility of the evaluation and reduce the difficulty of index scoring, the Delphi method is first used to conduct an expert survey, and then the secondary indicators are scored according to the NOAA ESI evaluation grading principle. Each evaluation indicator adopts a ten-point system. When the evaluation level is divided into 3 levels in total, the lowest level is assigned 3.0 points, the next is assigned 7.0 points, and the highest level is assigned 10.0 points; when the evaluation level is divided into 4 levels in total, the lowest level is assigned 2.5 points, the next is assigned 5.0 points, the next is assigned 7.5 points, and the highest level is assigned 10.0 points; when the evaluation level is divided into 10 levels in total, the lowest level is assigned 10.0 points, and each level increases by 1 point, and the highest level is assigned 10.0 points.

[0157] According to the comprehensive evaluation index of the sensitivity of green tide disaster-bearing bodies, the evaluation area is divided into five levels, namely, extremely sensitive (ESI is 8.0-10.0), highly sensitive (ESI is 5.0-8.0), sensitive (ESI is 3.0-5.0), slightly sensitive (ESI is 1.0-3.0) and insensitive area (ESI is 0-1.0).

[0158] Table 15 Analysis and evaluation of sensitive attributes of green tide disaster-bearing bodies

[0159]

[0160] Secondary indicator weight

[0161] The index weights were determined by combining Delphi and AHP. Several experts were selected to fill in the questionnaire and relevant information on the pairwise comparison matrix of the evaluation indexes. The questionnaires were collected and the comparison matrix A was obtained based on the results of each expert:

[0162]

[0163] Among them, a ii =1,a ij =1 / a ji

[0164] a ijis the comparison result of the importance of the i-th indicator and the j-th indicator to the upper-level indicator. The characteristic root method is used to obtain the weight coefficient of each evaluation indicator. The mean and standard deviation of the weight coefficient of each expert are statistically calculated, and the results and supplementary information are returned to the experts. All experts are asked to further complete the questionnaire based on the existing feedback results. After two surveys, the opinions of the experts are basically consistent. The mean of the indicator weight calculated at this time is used as the weight of the indicator. The specific green tide disaster-bearing body sensitivity attribute level indicator assignment and weight analysis are shown in Table 15.

[0165] Calculation of comprehensive evaluation index

[0166] The comprehensive evaluation index of green tide disaster-bearing body vulnerability is calculated according to the scores and weights of the secondary indicators. The formula is as follows:

[0167] ESI=∑ i＝1 W i F i

[0168] Where: ESI is the comprehensive vulnerability evaluation index of each green tide disaster-bearing body; W i is the weight of the i-th secondary indicator; F i Assignment of the i-th secondary indicator.

[0169] Furthermore, the emergency response capacity of green tide disasters is evaluated based on the daily response efficiency of the disaster-prone body, that is, the ratio of the daily green tide response biomass in the warning buffer zone of the disaster-prone body to the green tide biomass in the disaster-prone body buffer zone. The daily response efficiency of each disaster-prone body is used to characterize the size of the emergency response capacity. The formula is defined as follows:

[0170]

[0171] In the formula, DE d Represents the effectiveness of handling green tide disasters on the day;

[0172] Bm d Represents the average daily amount of green tide biomass removed around the disaster-affected body during the current period;

[0173] Bm a Represents the green tide biomass in the key area around the disaster-prone body that can cause the disaster-prone body to cause disasters.

[0174] Specifically, the main principles of the algorithm adopted by the green tide disaster comprehensive risk assessment model of the present invention are as follows.

[0175] (1) Dynamic construction method of green tide disaster event chain

[0176] Since the outbreak of green tide is a visible, gradual and continuous disaster-causing process for disaster-bearing bodies, the disaster-causing bodies mainly include secondary events of green tide disasters such as landscape destruction and equipment damage caused by large biomass, as well as environmental pollution and biological poisoning caused by rotten green tide. Therefore, in the actual emergency response process, the focus is mainly on the prevention and control of the risk of damage caused by green tide disasters to disaster-bearing bodies. From the perspective of the event chain node, that is, the first-level node of the event chain, that is, the prevention and control of the risk of economic losses that may be caused by green tide disasters to industries such as fisheries, tourism, nuclear power and important activity areas. From the time node of the event, a large-scale green tide disaster has occurred, but it has not yet affected the disaster-bearing body, or has just started to have a small impact on the disaster-bearing body. The green tide risk is controllable and the impact on the disaster-bearing body is controllable.

[0177] The main purpose of green tide emergency response is to prevent disaster-prone bodies from being affected by disasters. Therefore, it is mainly considered from the perspective of preventing and controlling the impact of green tide disasters on disaster-prone bodies. The disaster event scenario mainly selects the green tide disaster event chain risk that will affect the disaster-prone body for evaluation. Therefore, based on the correspondence between the type of disaster-prone body and the event chain node, as well as the time evolution sequence of the green tide causing disasters to the disaster-prone body, from the perspective of the disaster-prone body, according to the disaster-prone body that the green tide disaster is about to affect, the chain effect analysis model is applied to dynamically construct the green tide event chain such as Figure 1 Dynamic event chain of green tide disaster constructed based on chain effect model.

[0178] (2) Assessment of green tide disaster risk, vulnerability of disaster-bearing bodies, and emergency response capabilities

[0179] A multi-level evaluation index system is constructed for the danger of green tide disasters, the vulnerability of green tide disaster-bearing bodies and the emergency response capabilities of green tide disposal departments. The level of each indicator is determined according to the fuzzy evaluation method. Then, a semi-quantitative risk assessment is given for the danger of green tide disasters, the vulnerability of green tide disaster-bearing bodies and the emergency response capabilities of green tide disposal departments based on the hierarchical analysis method.

[0180] (3) Dynamic risk assessment of various disaster-prone bodies that may be affected by green tide disasters

[0181] For different types of industries that may be affected by green tide disasters, such as fisheries, tourism, nuclear power, protected areas and important activity areas, the difference in risk assessment lies in the different forms of disasters and the way of calculating the dangers of green tide disasters for different industry types, which is specifically reflected in the different graded calculation methods of danger assessment in the algorithm.

[0182] According to the different dangers of green tide disasters to different industrial economic types, it is specifically divided into three types: risk assessment of green tide disasters to fisheries and tourism, risk assessment of green tide disasters to nuclear power and protected areas, and risk assessment of green tide disasters to important activity areas.

[0183] The evaluation model of the present invention is based on the risk evaluation method of AHP. The model is suitable for dynamic risk evaluation of green tide disasters, and evaluates the dynamic risk size and risk level of green tide to important disaster-bearing bodies. It can be used to evaluate the danger of green tide disasters, the vulnerability of disaster-bearing bodies, and the emergency response capabilities. Finally, it can output the dynamic risk evaluation value of the disaster-bearing body caused by green tide disasters and the comprehensive risk level of regional green tide. It has the following advantages.

[0184] (1) Systematic analysis method

[0185] The analytic hierarchy process treats the research object as a system and makes decisions according to the thinking mode of decomposition, comparison, judgment and synthesis. It has become an important tool for system analysis developed after mechanism analysis and statistical analysis. The idea of ​​the system is not to cut off the influence of various factors on the results, and the weight setting of each layer in the analytic hierarchy process will directly or indirectly affect the results in the end, and the influence of each factor on the results at each level is quantified and very clear. This method can be especially used for the evaluation of systems with unstructured characteristics and the evaluation of systems with multiple objectives, multiple criteria and multiple periods.

[0186] (2) Simple and practical decision-making method

[0187] This method neither pursues advanced mathematics nor focuses on behavior, logic, and reasoning one-sidedly, but organically combines qualitative methods with quantitative methods to decompose complex systems, mathematicalize and systematize people's thinking processes, and is easy for people to accept. It can also transform multi-objective and multi-criteria decision-making problems that are difficult to quantify into multi-level single-objective problems, and finally perform simple mathematical operations after determining the quantitative relationship between the elements of the same level and the elements of the previous level through pairwise comparison. The calculation is simple, and the results are simple and clear, which are easy for decision makers to understand and grasp.

[0188] (3) Less quantitative data information required

[0189] The AHP method is mainly based on the evaluator's understanding of the nature and elements of the evaluation problem, and is more qualitative than general quantitative methods. Since the AHP method is a method that simulates people's thinking mode of decision-making process, the AHP method leaves the steps of judging the relative importance of each element to the brain, and only retains the impression of the elements in the human brain, which is converted into simple weights for calculation. This idea can handle many practical problems that cannot be solved with traditional optimization technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0190] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0191] Figure 1It is a dynamic event chain of green tide disasters constructed based on the chain effect model.

[0192] Figure 2 It is a risk assessment indicator system.

[0193] Figure 3 This is a dangerous function diagram of the green tide coverage duration in the core area.

[0194] Figure 4 It is a graph of the danger function of water temperature.

[0195] Figure 5 It is a graph of the dangerousness function of salinity.

[0196] Figure 6 It is a graph of the dangerousness as a function of wind speed. DETAILED DESCRIPTION

[0197] According to the comprehensive risk assessment model of green tide disaster events of the present invention, a green tide disaster scenario of a certain day is designed, and the risk of the disaster-bearing body and the green tide disaster risk are evaluated according to the algorithm. The main steps and calculation results are as follows:

[0198] First, obtain the green tide disaster parameters. The environmental monitoring parameters under the green tide disaster scenario are obtained as shown in Table 16.

[0199] Table 16 Monitoring parameters under green tide disaster scenario

[0200] Parameter name Value Description time June 10, 2018 Disaster Level none Water temperature 19.5℃ salinity 31.965 Wind speed 0.9m / s wind direction 249°

[0201] Secondly, the vulnerability analysis of the hazard-bearing body is carried out. According to the principle of dynamic evaluation of the vulnerability of the hazard-bearing body, the sea area is divided into The vulnerability index of the disaster-bearing body on each grid is ESI = ∑ i＝1 W i F i .

[0202] The vulnerability index and ESI score of the disaster-prone body are shown in Table 17. After superimposing and analyzing the historical disaster situation and current green tide monitoring information, the disaster risk index analysis table is shown in Table 18.

[0203] Table 17 Related parameters of the disaster-bearing body under the green tide disaster scenario

[0204]

[0205]

[0206] Then, the green tide disaster risk calculation is carried out, including:

[0207] (1) Disaster risk, as shown in Table 18 Disaster risk assessment table.

[0208] Table 18 Disaster risk assessment table

[0209]

[0210] (2) Buffer zone hazard assessment: Based on the relevant parameters of the disaster-prone body under the green tide disaster scenario in Table 18, the disaster prevention core area and disaster reduction warning area of ​​the disaster-prone body are calculated respectively. Further, based on the green tide disaster monitoring and forecasting situation, the green tide coverage duration of the core area, the buffer zone monitoring coverage rate, and the buffer zone forecast coverage rate are analyzed and calculated.

[0211] In this case, according to the information on the closest distance between the green tide distribution and the disaster-prone body, it is judged that there is no green tide coverage information in the core area of ​​the disaster-prone body. Therefore, the green tide coverage duration index information of the core area is all 0. The monitoring coverage rate information table of the disaster-prone body warning buffer zone in Table 19 and the forecast coverage rate information table of the disaster-prone body buffer zone in Table 20 are calculated, and the hazard assessment table of the disaster-prone body warning buffer zone in Table 21 is further calculated.

[0212] Table 19 Monitoring coverage information of disaster-prone body warning buffer zone

[0213] Serial number type First level buffer Secondary Buffer Three-level buffer Four-level buffer 0 Protected Areas 0.0％ 1.3％ 4.6％ 7.7％ 1 Protected Areas 0.0％ 1.4％ 6.6％ 9.1％ 2 Protected Areas 0.0％ 1.4％ 8.5％ 8.3％ 3 Protected Areas 0.0％ 0.0％ 2.0％ 3.4％ 4 Beach 0.0％ 0.0％ 0.4％ 5 Beach 0.0％ 0.0％ 3.1％ 6 Tourist Area 0.0％ 0.0％ 1.2％ 7 Important activity areas 3.0％ 9.4％ 7.2％ 5.3％ 8 Raft culture 0.0％ 0.0％ 0.0％ 9 Raft culture 0.0％ 0.0％ 0.0％ 10 Raft culture 0.0％ 0.0％ 0.0％ 11 Raft culture 0.0％ 0.0％ 0.0％ 12 Raft culture 0.0％ 0.0％ 0.0％ 13 Raft culture 0.0％ 0.0％ 0.0％ 14 Raft culture 0.0％ 0.0％ 0.0％ 15 Raft culture 0.0％ 0.0％ 0.0％ 16 Raft culture 0.0％ 0.0％ 0.0％ 17 Raft culture 0.0％ 0.0％ 0.2％ 18 Raft culture 0.0％ 0.0％ 0.1％

[0214] Table 20 Forecast coverage rate information of disaster-prone body warning buffer zone

[0215] Serial number type First level buffer Secondary Buffer Three-level buffer Four-level buffer 0 Protected Areas 0.0％ 6.2％ 17.2％ 29.6％ 1 Protected Areas 0.0％ 7.5％ 23.4％ 33.8％ 2 Protected Areas 0.0％ 9.7％ 27.8％ 32.8％ 3 Protected Areas 0.0％ 2.7％ 9.3％ 14.0％ 4 Beach 0.0％ 0.0％ 5.3％ 5 Beach 0.0％ 3.2％ 14.3％ 6 Tourist Area 0.0％ 4.3％ 9.1％ 7 Important activity areas 3.0％ 1.4％ 8.9％ 7.9％ 8 Raft culture 0.0％ 0.0％ 1.8％ 9 Raft culture 0.0％ 0.0％ 1.7％ 10 Raft culture 0.0％ 0.0％ 1.6％ 11 Raft culture 0.0％ 0.0％ 0.7％ 12 Raft culture 0.0％ 0.0％ 0.5％ 13 Raft culture 0.0％ 0.0％ 0.6％ 14 Raft culture 0.0％ 0.0％ 0.6％ 15 Raft culture 0.0％ 0.0％ 0.6％ 16 Raft culture 0.0％ 0.0％ 0.1％ 17 Raft culture 0.0％ 0.0％ 5.2％ 18 Raft culture 0.0％ 0.0％ 3.5％

[0216] Table 21 Hazard Assessment Table for Disaster-Bearing Body Warning Buffer Zone

[0217]

[0218] (3) Hazard of sea conditions, as shown in Table 22, Hazard Evaluation Table of Sea Conditions.

[0219] Table 22 Sea condition hazard evaluation table

[0220]

[0221] Subsequently, the emergency response capability analysis was conducted. According to the biomass of green tide disposal and the daily disposal efficiency of the disaster-bearing body, the overall emergency response capability of green tide disposal was evaluated as average, with a score of 4.

[0222] Finally, a comprehensive risk assessment of disaster risk of disaster-prone bodies and green tide disasters is conducted.

[0223] (1) The disaster risk assessment of a single disaster-bearing body is shown in Table 23

[0224] Table 23 Disaster risk assessment table for a single disaster-bearing body

[0225]

[0226] (2) Overall risk assessment of this green tide event

[0227]

[0228] Therefore, the green tide disaster event on June 10th generally constitutes a Level IV risk (blue).

Claims

1. A dynamic risk assessment model for green tide disasters based on event chains. The assessment process of the model includes: Step 1: Delineate a third-level or fourth-level buffer zone with the disaster-prone body as the center, and construct a dynamic event chain using a chain effect analysis model based on the green tide disaster monitoring range, prediction range, and the disaster-prone body and its secondary / derivative event list within the intersection range with the buffer zone; Step 2: Grid the entire sea area including the green tide disaster monitoring range, prediction range and the potentially affected area where the disaster-prone body is located, and conduct vulnerability assessment of the disaster-prone body based on the grid; Step 3: Based on the quantitative evaluation method of green tide disaster hazard and green tide disaster emergency response capability indicators, obtain the hazard value and emergency response capability evaluation value of green tide disaster to different disaster-bearing bodies; Step 4: Divide the grids based on the vulnerability of the disaster-bearing body, use the analytic hierarchy process, and apply the calculation formula of hazard*vulnerability / emergency capacity to conduct dynamic risk assessment on the secondary node events of the event chain of industrial economic loss events that may be caused by green tide disasters within each grid, including fisheries, tourism, nuclear power, protected areas and important activity areas; The calculation formula is as follows: M1=(H d +H b +H e ) / 3 In the formula, r i is the dynamic risk index of green tide disaster to the i-th sea area grid, ranging from 0 to 10; M1 is the risk index of green tide disaster to current environment-related targets, ranging from 0 to 10; H d is the disaster risk index, ranging from 0 to 10; H b is the buffer zone hazard index, ranging from 0 to 10; H e is the sea condition danger index, ranging from 0 to 10; is the disaster index value, is the weight of disaster indicators, which include green tide disaster level, historically prone areas, and the closest distance between green tide and disaster-bearing body; a is the sequence number of the warning buffer, representing the relevant attributes of the a-th warning buffer; b is the bth risk indicator element of the ath warning buffer zone; W ab is the risk index weight value of the bth risk index element in the ath warning buffer zone; X ab is the risk index value of the bth risk index element in the ath warning buffer zone; is the sea condition index value, is the weight of sea condition indicators, which include water temperature, wind speed and salinity; M2 i is the vulnerability index of the ith grid, ranging from 0 to 10; k is the kth vulnerability indicator element in the vulnerability indicator system; W k is the weight value of the kth vulnerability indicator element; F k is the vulnerability index value of the kth vulnerability index element; M3 is the comprehensive evaluation index of emergency response capability, ranging from 0 to 10; Step 5: When the green tide disaster divides the entire sea area into grids, each disaster-prone body contains multiple vulnerability assessment grids. The following takes a single disaster-prone body as the assessment object and calculates the dynamic risk of the green tide to the single disaster-prone body; The calculation formula is as follows: Where n is the number of vulnerability assessment grids contained in the hazard-bearing body; C j is the disaster risk index of the jth disaster-prone body, ranging from 0 to 10; r i is the risk index of the ith vulnerability assessment grid, ranging from 0 to 10; Step 6: According to the green tide dynamic risk assessment formula and value range in step 5, the dynamic risk level of the green tide disaster event to the disaster-bearing body is divided into 4 levels; Step 7: Calculate the disaster risk index of green tide disaster for all disaster-bearing bodies and comprehensively evaluate the overall risk level of green tide disaster. The calculation formula is as follows: In the formula, R g It is the overall risk level of green tide disaster.

2. The evaluation model according to claim 1, characterized in that The assessment model also includes step 8, which divides the dynamic risk level of the green tide disaster event to the disaster-prone body into 4 levels according to the calculation formula and value range of the comprehensive risk index of the green tide disaster event in step 7, and divides the level according to the value of the risk index, and the risk colors are marked as red, orange, yellow and blue respectively.

3. The evaluation model according to claim 1 or 2, characterized in that: In step 1, a chain effect analysis model is used to construct a dynamic event chain, and its first-level node events are analyzed, including fishery disasters, tourism disasters, nuclear power disasters, protected area disasters, and important activity area disasters.

4. The evaluation model according to claim 1 or 2, characterized in that: The green tide disaster risk assessment index system in step 3 includes disaster indicators, warning buffer zone indicators, and sea condition indicators.

5. The evaluation model according to claim 4, characterized in that The early warning buffer zone indicators include green tide monitoring coverage rate, green tide forecast coverage rate, and green tide coverage duration in the core area.

6. The evaluation model according to claim 4, characterized in that The information of the above indicators adopts the information data released by the Ministry of Natural Resources.

7. The evaluation model according to claim 1 or 2, characterized in that: The output results of the model mainly include green tide disaster hazard score, hazard distribution map, disaster-bearing body vulnerability distribution map and green tide comprehensive risk assessment results.

8. The application of the assessment model described in any one of claims 1 to 7 in green tide disaster risk assessment, dynamic assessment of the risk level and risk size of green tide to important disaster-prone objects, and assessment of the hazard of green tide disasters, vulnerability of disaster-prone objects, and emergency response capabilities, ultimately outputting the dynamic risk assessment value of the disaster-prone objects caused by green tide disasters and the comprehensive risk level of green tide events.

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