Table of Comparison of Importance of Each Pair of Criteria

The risk level of each criterion in the process of analyzing the risk of environmental degradation of seaports.

AHP is one of the multi-objective decision-making methods proposed by Thomas L. Saaty (1987)[76]. AHP is a quantitative method used to arrange decision alternatives and select an alternative that satisfies given criteria. Based on the principle of pairwise comparison, the AHP method can be described with three main principles, namely analysis, evaluation and synthesis. AHP answers questions such as “Which alternative should we choose?” or “Which alternative is the most important?” by selecting the best alternative that satisfies the decision maker’s criteria based on comparing pairs of alternatives and a specific calculation mechanism[31].

AHP is widely used in risk assessment to determine the importance of hazards that cause a risk event.

Figure 2.2. Multi-criteria analysis diagram

The weighting of the evaluation criteria is performed by the pairwise comparison method based on the expert opinions. The priority value is evaluated according to the Saaty scale. The expert opinions on these criteria are also checked for consistency through the RI index.

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Table 2.3. Table comparing the importance of each pair of criteria

Column A

C ck a lot		R t much		More		Few		Equal		Few		More		So many		Too much	Column B
Criterion A1	9	8	7	6	5	4	3	2	1	2	3	4	5	6	7	8	9	Criteria A2
Criteria A2	9	8	7	6	5	4	3	2	1	2	3	4	5	6	7	8	9	Criteria A3
Criterion A3	9	8	7	6	5	4	3	2	1	2	3	4	5	6	7	8		Criterion A1

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The weights of the criteria are calculated according to the formula:

()(3)

∑

(4)

In there:is the priority level of criterion Aj compared to the corresponding criterion Ak according to expert assessment (j,k = 1 …m).

𝑐𝑗 Average rating of experts for criterion A𝑗

𝑗 is the weight of criterion Aj

Before drawing a final conclusion, it is necessary to ensure the consistency of the expert's assessment throughout the application of the method. The consistency ratio (CR) is determined as follows:

(5)

∑

(6)

(7)

m is the number of elements compared pairwise in one computation, which is the size of the computation matrix.

RI (random index): random index. RI is determined from a given table of numbers (see Table 2.4, this table only presents RI values for up to 9 criteria).

Table 2.4. Random indicators corresponding to the number of selection criteria considered

1	2	3	4	5	6	7	8	9
RI	0.00	0.00	0.58	0.9	1.12	1.24	1.23	1.41	1.49

In any case, the CR should not be greater than 10%. Failure to do so indicates inconsistency in the expert's assessment and requires re-evaluation and recalculation.

The process of determining the weight of the criteria goes through 3 steps: Step 1, experts make their choices; Step 2, experts with CR > 10% revise their choices to ensure that the CR index meets the requirements; Step 3, experts refer to the choices of other experts or discuss directly with the person asking for advice to better understand the criteria and reconsider their choices accordingly.

7/ Delphi method

This method is a technique to support the collection of information and knowledge from a group of experts for questionnaires or assessments on an issue. The Delphi method aims to get closer to consensus through rounds of sending questionnaires [77].

The Delphi technique is a process for achieving a reliable consensus of views among a group of experts. Although the term is now commonly used to refer to any form of brainstorming, an essential feature of the Delphi technique as originally developed is that experts express their views individually and anonymously, while still accessing the views of other experts as the process progresses. The Delphi technique can be applied at any stage of the risk management process or at any stage in the life cycle of a system, whenever a consensus of views among experts is required[18].

The Delphi method is used in combination with the analytical power factor (AHP) method [57, 58] to support experts in the process of making their judgments about the importance between the compared criteria. These two methods are widely used in different research fields to use the knowledge and experience of experts in conditions where there is not enough analytical data to compare between criteria. In the field of safety and environmental risk assessment, these two methods are also used by many authors [31-33, 37] to identify hazards that need to be prioritized for remediation.

In this Thesis, 20 experts in the fields of: Marine Science; Port Engineering; Environmental Chemistry; Occupational Safety, Health and Environment (HSE) and Port Management were consulted and commented. The opinions of the experts were summarized according to T. Saaty's rating scale in the table below (Table 2.5).

Table 2.5. Rating the relative importance of each criterion

STT

Priority level	Explain	Rating Points
1	Equal importance (EQ)	Two components have equal properties	1
2	Moderate importance of one over another (MO)	Experience and opinion leans slightly towards one over the other.	3

STT

Priority level	Explain	Rating Points
3	Essential or strong importance (ES)	Experience and opinion leans more heavily towards one than the other.	5
4	Very strong importance - VE)	One component is given much stronger priority than the other and is expressed in practice.	7
5	Extremely important (Extreme importance - EX)	The importance of one component over another is paramount.	9

8/Score evaluation method

The scoring method is a technique of quantifying by scores the parameters of the indicators used to evaluate specific criteria in the risk assessment criteria set. The assessment score corresponds to the level of risk or the level of damage of each criterion. The assessment scale depends on the person who builds the criteria set and can be from 1 to 10 or from 1 to 4. In this study, the scale from 1 to 4 is used to correspond to the levels of degradation risk and degradation levels explained in Table 2.6 and Table 2.7. Information collected from the Port Information Form is the basis for assessing the score of each criterion.

Table 2.6. Scorecard for assessing the risk of causing recession

Rating Points

Risk level	Describe
1	Short	Rare but possible event
2	Medium	Events that occur regularly in cycles
3	High	Events that occur frequently and not periodically
4	Very high	The event is certain to happen.

Table 2.7. Scorecard for assessing the level of degradation

Rating Points

Degree of degradation

Describe

Disaster

Incidents occur on a large scale (inter-regional, inter-national)

Large scale damage to property, people, environment...

Rating Points

Degree of degradation	Describe
3	Serious	Large-scale (regional) incidents Serious damage to property, people, environment...
2	significant	Incidents occur on a medium scale (range of incident area and surrounding areas) Significant damage to property, health, environment...
1	Small	Incidents occur on a small scale (area where the incident occurs) Minor damage to property, health, environment

2.2.1.3. Steps to conduct research

Based on the IMO's Official Safety Assessment Guide for Maritime Operations (FSA) first issued in 2002 and updated in 2015[27] and the Risk Assessment Procedure presented in the research methodology section. The research problem implementation process is carried out according to the following steps:

- Step 1: Collect information, assess the current status of environmental management, protection and prevention and response to environmental incidents from the process of storing and loading HNS cargo at the group of seaports in the North of Vietnam. Identify risks of environmental degradation from the process of storing and loading HNS cargo at seaports.

- Step 2: Develop and test the application of a set of criteria to assess the risk of environmental degradation from the process of storing and loading HNS goods at the group of seaports in the North of Vietnam.

Step 3: Analyze and identify the causes that need to be overcome to prevent environmental degradation and pollution in the storage and loading and unloading of HNS goods at the ports in the Northern seaport group.

Step 4: Propose solutions to minimize the risk of environmental degradation caused by HNS storage and loading activities at the group of seaports in the North of Vietnam.

The process of analyzing and assessing the risk of environmental degradation from the storage and loading of HNS goods at seaports is carried out according to the following procedure:

Identify the risks of recession

Preliminary hazard analysis method

Checklist method

Identify sources of risk and affected subjects

Develop criteria for assessing the risk of causing depression

degradation and criteria for assessing the level of degradation

Direction

AHP method

Technique

Delphi

Direction

Binary screening method

Preliminary screening of ports with HNS cargo warehousing and loading activities in the group of seaports in the North of Vietnam

Survey, investigation

The port has no HNS storage and loading activities.

Port with HNS warehousing and loading activities

Remove

Analysis in next step

Determine the weight of the criteria

Determining the risk of degradation

Score method

Determine the degradation level value

Matrix

consequence/probability

Classification of environmental degradation risks

Figure 2.3. Process of analyzing, identifying and assessing the risk of environmental degradation

school at the seaport

2.3. Source of documents

To carry out the topic, the database used includes documents, data collected from ministries, branches and localities and the results of surveys, field interviews and expert opinions.

Table 2.8. Research database

STT

Data name	Source
I. Statistics
1	Cargo throughput through the Northern seaport group from 2016-2020	Vietnam Maritime Administration and local maritime port authorities
2	Statistics of maritime accidents from 2011-2020	Vietnam Maritime Administration
3	Data on environmental quality in seaport areas and coastal areas in northern Vietnam	Ministry of Transport, Vietnam Maritime University, Institute of Marine Resources and Environment
4	List of seaports in Vietnam	Vietnam Maritime Administration
II. Documents
1	International conventions related to environmental protection in maritime activities, Research reports in the field of cargo transportation dangerous, toxic	The electronic portal of the World Maritime Organization (imo.org) and relevant organizations relate to
2	Legal and sub-legal documents of the Government and the Ministry of Transport on the maritime sector	Government electronic information portal (chinhphu.vn), Ministry of Transport (mt.gov.vn) and Vietnam Maritime Administration (vinamarine.gov.vn)
3	Development strategies and master plans for the development of Vietnam's seaport and maritime transport systems.
4	Doctoral theses, scientific research topics in the maritime field and other fields related to the thesis.	Ministry of Education and Training electronic information portal (moet.gov.vn), national library, Institute of Marine Resources and Environment Library, Vietnam Maritime University Library.

STT

Data name	Source
5	Published works on environmental risk assessment, risk assessment at seaports, transportation of hazardous goods, marine environmental pollution...	Books, magazines, domestic and international scientific reports
III. Field research data
1	Survey of current status of operations, environmental protection infrastructure, incident prevention and response at seaports	Information form (30 forms)
2	Expert opinion form to determine the weight of risk criteria (Questionnaire).	Results of expert consultation (20 votes).
IV. Data from research topics
1	Assessing the current situation and developing a process for controlling and responding to incidents and environmental risks for dangerous goods at Vietnamese seaports, applying a trial application in the Hai Phong port area. Ministry of Transport Environmental Protection Project 2017-2018. MT 171003	Vietnam Maritime University
2	Assessment of the ability to meet the requirements for waste collection and treatment at Vietnamese seaports when participating in appendices 3,4,5,6 of the Marpol 73/78 Convention. Environmental protection project at the Ministry of Transport, Code MT 141001
3	Assessment of the impact of group 1 seaport activities on the environment. Environmental protection project at the Ministry of Transport level, 2018-2019.
4	Survey and assessment of current status and development of technical guidelines on environmental protection in the transportation of dangerous goods by sea. Environmental protection project at the Ministry of Transport level, Code MT 201010

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