Distribution of oil spill response capability through considering probable incident, environmental sensitivity and geographical weather in Vietnamese waters

Figures & data

Table 1. Linguistic responses and fuzzy scale transformation chart (Saaty 2008; Buyukozkan, 2004).

Linguistic scale	TFN scale	TFN reciprocal scale
Just equal	(1,1,1)	(1,1,1)
Equal Importance	(1/2,1,3/2)	(2/3,1,2)
Weakly more important	(1,3/2,2)	(1/2,2/3,1)
Strongly more important	(3/2,2,5/2)	(2/5,1/2,2/3)
Very strongly more important	(2,5/2,3)	(1/3,2/5,1/2)
Absolutely more important	(5/2,3,7/2)	(2/7,1/3,2/5)

Table 2. Values of the Random Index (RI) (Saaty and Vargas 2001).

n	1	2	3	4	5	6	7	8	9	10
RI	0	0	0.52	0.89	1.11	1.25	1.35	1.40	1.45	1.49

Table 3. Detailing important factors for evaluation of VRC Index.

Goal	Upper level	Lower level	Detail
VRC	Oil spill sensitive area protected level: OSS	High priority protected areas (HPA)	Marine protected areas (World heritage sites, national park, marine nature reserves, etc.) Widlife protected include marine bird (wetlands as waterfowl habitat in Ramsar site), marine mammals and sea turtles (Sea turtles spawning ground and habitat area). Coastal habitat (consists of mangrove and mudflat forest, coral reefs, seagrass beds)
			Aquaculture (fish stocks, fish and shellfish farming, seaweed cultivation, water intakes for hatchery, etc.)
			Oil port area
		Medium priority protected areas (MPA)	Beach, tourism and recreation areas
			Salt field
			Intensive land of rice and vegetables coastal area
			Subsistence, artisanal and commercial fishing, and fishing villages
			Main port and marinas
			Urban residental area, rocky beach, sandy beach for many users
		Low priority protected areas (LPA)	National park, nature reserves, habitat on land, industrial land
			Land for planting industrial trees, perennial trees, coastal area a little used
			Small port and marinas
	Probability of oil spill incident: POS	No. Vessel enter and depart from area (VED)	Marine traffic density
		Estimation of maximum amount of oil spill in the areas (EMO)	Type of oil
		Industrial installation (IND)	Oil storage tanks
			Type of oil import-export area
		Offshore operational oil port (OSP)	Oil rigs, platforms operations, SPM, SPSOs
			Oil and gas pipeline system
		Historical oil Spill incident (HOS)	Spill frequency
			Amount of oil spill
	Geographic condition (seasonal, meteorological condition); GEO	Distance (DIS)	Farthest point
		Sea state (Wind, wave) (SSW)	Direction
			Intensity
		Tidal current (TID)	Direction
			Intensity
		Visibility (VIS)	Daylight
			Darkness
		Temperature (TEM)	Average highest temperature
			Average lowest temperature

Figure 1. Hierarchical VRC model.

Figure 2. Flowchart of setting up OSRC.

Figure 3. Sample pair-wise comparison matrices.

Table 4. Weighted scores for each factor by Fuzzy-AHP.

Upper evaluation		Lower evaluation	Local weight	Global weight
POS	0.619	VED	0.300	0.186
		EMO	0.273	0.169
		IND	0.156	0.097
		OSP	0.151	0.093
		HOS	0.120	0.074
OSP	0.236	HPA	0.521	0.123
		MPA	0.312	0.074
		LPA	0.167	0.039
GEO	0.145	DIS	0.325	0.047
		SSW	0.263	0.038
		TID	0.231	0.033
		VIS	0.082	0.012
		TEM	0.059	0.009

Table 5. Present status of areal probability factors.

Region	Area	VED (No.)	EMO (Tons)	IND (Tons)	OSP (No.)	HOS (Case)
NOSRCEN	N1- Hai Phong	26810	6000	2362100	5	10
	N2- Thanh Hoa*	7643	45000	1125400	3	3
	N3- Ha Tinh+	2202	2700	158000	4	2
SOSRCEM	C1 – Da Nang	7160	4500	409500	8	12
	C2 – Quang Ngai+	8030	22500	1281900	5	15
	C3 – Khanh Hoa	4894	22500	1124900	6	2
NASOS	S1 – Vung Tau	41405	45000	3513860	116	66
	S2 – Ca Mau+	591	18000	65000	4	7

Table 6. Present status of areal oil spill sensitivity factors.

Region	Area	High priority area (HPA)			Medium priority area (MPA)						Low priority area (LPA)
		Marine protected area (km^2)	Aquaculture (km^2)	Oil port (No.)	Beach, tourism and recreation areas (ha.)	Salt field (ha.)	Intensive land of rice and vegetables coastal area (ha.)	Subsistence, artisanal and commercial fishing, and fishing villages (tons)	Main port and marinas (No.)	Urban residental area, rocky beach, sandy beach for many users (People)	National park, nature reserves, habitat on land, industrial land (km^2)	Land for planting industrial trees, perennial trees (km^2)	Small port and marinas (No.)
NOSRCEN	N1- Hai Phong	3567.91	60.5	26	24130	196	429.5	241359	3	6848	18096	25.5	3
	N2-Thanh Hoa*	67.00	48.5	6	23750	600	818.7	211912	2	7586.9	263118	149.7	2
	N3- Ha Tinh+	0.00	12.5	7	4938	0	158.4	76369	1	2144.4	200003	35.1	2
SOSRCEM	C1 – Da Nang	587.44	19.2	11	18635	0	196.4	163160	2	4307.2	543747	70.9	3
	C2 – Quang Ngai+	243.85	9.4	9	6346	315	235.8	438,098	2	3675.5	35937	69.2	2
	C3 – Khanh Hoa	738.26	5.9	5	13450	2371	81.3	176056	3	1815.2	68843.5	35.5	1
NASOS	S1 – Vung Tau	631.54	177.2	32	51572	3300	1021.9	952670	4	15970.1	45974	163.3	7
	S2 – Ca Mau+	15451.63	576.7	5	57007	2300	1063.5	802270	0	3885.5	17806.7	5.9	3

Table 7. Present status of areal geographic conditions.

Region	Area	Distance to spill site (Nm)	Sea state (average wind intensity)	Tidal current (max velocity – cm/s)	Visibility	Temperature (water surface – °C)
NOSRCEN	N1- Hai Phong	110	2.475	10	1700	19
	N2-Thanh Hoa*	62	1.800	5	1659	20
	N3- Ha Tinh+	96	2.000	2	1761	21
SOSRCEM	C1 – Da Nang	86	1.775	1	2061	24
	C2 – Quang Ngai+	170	1.800	1	2359	25
	C3 – Khanh Hoa	55	2.400	10	2606	25
NASOS	S1 – Vung Tau	150	2.400	30	2667	25
	S2 – Ca Mau+	180	1.933	10	2321	27

Table 8. Resulting average normalization of present status data.

Region	Area	HPA	MPA	LPA	VED	EMO	IND	OSP	HOS	DIS	SSW	TID	VIS	TEM
NOSRCEN (0.2932)	N1	0.1638	0.1088	0.0638	0.2715	0.0361	0.2353	0.0331	0.0893	0.121	0.1492	0.1449	0.0992	0.1180
	N2	0.0386	0.1234	0.1924	0.0774	0.2708	0.1121	0.0199	0.0000	0.068	0.1085	0.0725	0.0968	0.1242
	N3	0.0277	0.0324	0.1059	0.0223	0.0162	0.0157	0.0265	0.0000	0.106	0.1206	0.0290	0.1027	0.1304
SOSRCEM (0.2847)	C1	0.0525	0.0677	0.2379	0.0725	0.0271	0.0408	0.0530	0.1071	0.095	0.1070	0.0145	0.1203	0.1491
	C2	0.0370	0.0776	0.0806	0.0813	0.1354	0.1277	0.0331	0.1339	0.187	0.1085	0.0145	0.1377	0.1553
	C3	0.0302	0.1037	0.0550	0.0496	0.1354	0.1120	0.0397	0.0179	0.061	0.1447	0.1449	0.1521	0.0000
NASOS (0.4221)	S1	0.1804	0.2947	0.2123	0.4194	0.2708	0.3500	0.7682	0.5893	0.165	0.1447	0.4348	0.1556	0.1553
	S2	0.4697	0.1917	0.0520	0.0060	0.1083	0.0065	0.0265	0.0625	0.198	0.1166	0.1449	0.1355	0.1677

Figure 4. A scenario of an oil spill response in Thanh Hoa area.

Table 9. Final weight for setting up OSRC for areas.

Region	Area	HPA	MPA	LPA	VED	EMO	IND	OSP	HOS	DIS	SSW	TID	VIS	TEM
NOSRCEN (0.2837)	N1	0.0305	0.0184	0.0062	0.0252	0.0027	0.0289	0.0024	0.0035	0.0057	0.0057	0.0048	0.0012	0.0011
	N2	0.0072	0.0209	0.0187	0.0072	0.0200	0.0138	0.0015	0.0000	0.0032	0.0041	0.0024	0.0012	0.0011
	N3	0.0052	0.0055	0.0103	0.0021	0.0012	0.0019	0.0020	0.0000	0.0050	0.0046	0.0010	0.0012	0.0012
SOSRCEM (0.2394)	C1	0.0098	0.0114	0.0231	0.0067	0.0020	0.0050	0.0039	0.0042	0.0045	0.0041	0.0005	0.0014	0.0013
	C2	0.0069	0.0131	0.0078	0.0076	0.0100	0.0157	0.0024	0.0052	0.0088	0.0041	0.0005	0.0017	0.0014
	C3	0.0056	0.0175	0.0053	0.0046	0.0100	0.0138	0.0029	0.0007	0.0029	0.0055	0.0048	0.0018	0.0000
NASOS (0.4769)	S1	0.0336	0.0498	0.0206	0.0390	0.0200	0.0431	0.0568	0.0230	0.0078	0.0055	0.0143	0.0019	0.0014
	S2	0.0874	0.0324	0.0050	0.0006	0.0080	0.0008	0.0020	0.0024	0.0093	0.0044	0.0048	0.0016	0.0015

Table 10. Final weight and OSRC (4 days).

Region	Area	Final weight	OSRC (tons)	Current capability (tons)	Difference
NOSRCEN	N1	0.1376	633	1764	(‒)1131
	N2	0.1035	476	0	476
	N3	0.0426	196	0	196
	Sum.	0.2837	1305	1764	(‒)459
SOSRCEM	C1	0.0786	362	961	(‒)599
	C2	0.0852	392	0	392
	C3	0.0756	348	0	348
	Sum.	0.2394	1101	961	140
NASOS	S1	0.3167	1457	1875	(-)419
	S2	0.1602	737	0	737
	Sum.	0.4769	2194	1875	318

Table 11. Regional OSRC for the worst case discharge in North Region.

Region	Area	Distance (NM)	Time dispatching (hour)	Time operating (hour)	OSRC Simulation(tons)	Existing capability
NOSRCEN	N1- Hai Phong	100	9	28	554	1764
	N2-Thanh Hoa*	0	0	32	476	0
	N3- Ha Tinh+	60	5	28	171	0
SOSRCEM	C1 – Da Nang	241	22	21	237	961
	C2 – Quang Ngai+	295	27	17	208	0
	C3 – Khanh Hoa	506	46	13	141	0
NASOS	S1 – Vung Tau	690	63	8	364	1875
	S2 – Ca Mau+	850	94	2	46	0

Table 12. Gathering OSRCs in Thanh Hoa area.

Hour working		1	2	3	4	5	6	7	8
Cumulative amount of oil recovery (ton)	Day 1	15	30	45	60	101	142	183	235
	Day 2	287	351	415	479	543	607	671	735
	Day 3	799	863	938	1013	1088	1163	1238	1313
	Day 4	1434	1555	1676	1797	1918	2039	2183	2327

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