Survey elements, measurement, and frequency in hydrographic and environmental surveys in coastal and island areas in Vietnam from January 27, 2025

Tan Dai

09:00, 19/12/2024

Below are the survey elements, measurement, and frequency in hydrographic and environmental surveys in coastal and island areas in Vietnam from January 27, 2025 from January 27, 2025, as stipulated in Circular 31/2024/TT-BTNMT.

Surveyed factors, measurements, and measurement frequency in hydrometeorology, coastal and island environment surveys from January 27, 2025

Survey elements, measurement, and frequency in hydrographic and environmental surveys in coastal and island areas in Vietnam from January 27, 2025 (Image from the Internet)

On December 12, 2024, the Minister of Natural Resources and Environment of Vietnam issued Circular 31/2024/TT-BTNMT on Technical Regulations for Surveying and Assessing Hydrometeorology and Coastal and Island Environment.

Survey elements, measurement, and frequency in hydrographic and environmental surveys in coastal and island areas in Vietnam from January 27, 2025

As stipulated in Article 5 of Circular 31/2024/TT-BTNMT, the surveyed factors, measurements, and measurement frequency for hydrometeorology and coastal and island environment surveys are as follows:

No	Survey Content	Measurement Factor	Measurement Frequency
No	Survey Content	Measurement Factor	Wide Range Station	Continuous Station
I	Marine Meteorology Survey
1	Marine Meteorology	Wind, cloud cover; visibility, air pressure, air temperature, air humidity, other weather phenomena	1 time at all survey stations	8 times at 1, 4, 7, 10, 13, 16, 19, and 22 hours daily
II	Hydrometeorology Survey
1	Hydrometeorology	Ocean waves	Survey 1 time by sight at all stations	1 hour/data point (recorded automatically)
		Water level	Not surveyed	1 hour/data (measured manually), 15 minutes/data (with automatic recorder)
		Current	1 time at all survey stations	1 hour/data point (with direct measurement device) 15 minutes/data (with automatic recorder)
III	Marine Environment Survey
1	Transparency	Sea water transparency	1 time at all survey stations (measure in morning or evening)	Measure in the morning or evening during 1 day (every day in the observation period)
2	Marine Water Environment	Turbidity, pH, Dissolved Oxygen (DO), temperature and salinity	1 time at all survey stations	Sample at standard layers during high tide, low tide/day, every 2 days
		Mineral oils, nutrients (NH₄^+^, PO₄^3-^); Heavy metals (Cu, Pb, Cd, Fe, Mn, Zn, As, Hg, Total Cr, Cr^6+^)	1 time at all survey stations	Sample at standard layers during high tide, low tide/day, every 2 days
		Total suspended solids (TSS), Fluoride (F^-^), Cyanide (CN^-^), Total phenol, Total Coliform, Total petroleum hydrocarbons (TPH), Total DDT, Anionic surfactant	1 time at all survey stations	Sample at standard layers during high tide, low tide/day, every 2 days
3	Air Environment	Air environment: Total suspended particles (TSP), SO₂, NO₂, CO, O₃.	1 time at all survey stations	8 times at 1, 4, 7, 10, 13, 16, 19, and 22 hours daily
4	Marine Sediment Environment	Heavy metals (As, Cd, Cu, Pb, Fe, Zn, Hg, Total Cr)	1 time at all survey stations	1 time per session at all survey stations (minimum 02 times/year)
		Total Hydrocarbon	1 time at all survey stations	1 time per session at all survey stations (minimum 02 times/year)
		Chlorinated hydrocarbon pesticides and polychlorobiphenyl (DDD, DDE, DDT, Dieldrin, Endrin, Lindan, Total Polychlorobiphenyl (PCB), Heptachlor epoxide)	1 time at all survey stations	1 time per session at all survey stations (minimum 02 times/year)
		Dioxin and Furan	1 time at all survey stations	1 time per session at all survey stations (minimum 02 times/year)
		Phenol	1 time at all survey stations	1 time per session at all survey stations (minimum 02 times/year)
		Cyanide (CN)	1 time at all survey stations	1 time per session at all survey stations (minimum 02 times/year)
		Polycyclic Aromatic Hydrocarbons (PAH) (Acenaphthene, Acenaphthylene, Anthracene, Benzo[a]anthracene, Benzo[e]pyrene, Chrysene, Dibenz[a,h]anthracene, Fluoranthene, Fluorene, 2-Methylnaphthalene, Naphthalene, Phenanthrene, Pyrene)	1 time at all survey stations	1 time per session at all survey stations (minimum 02 times/year)
IV	Seafloor Depth Survey
1	Seafloor depth	Point depth measurement, depth transect, sampling site positioning, observation station deployment	1 time at all survey stations	1 time at all survey stations
V	Marine Ecology Survey
1	Marine Ecology	Phytoplankton, zooplankton	Sample 1 time at all survey stations	Collect samples 8 times at 1, 4, 7, 10, 13, 16, 19, and 22 hours/station
1	Marine Ecology	Benthic animals, sea fish, algae, seagrass, coral, mangrove vegetation	Sample 1 time at all survey stations	Sample 1 time at all survey stations

Instructions on data processing and result reporting in marine meteorology survey in Vietnam

Data processing and result reporting in marine meteorology surveys are conducted following the provisions in Article 10 of Circular 31/2024/TT-BTNMT as follows:

- Adjust temperature and air humidity measurements according to calibration documents, use humidity tables to calculate relative humidity, absolute humidity, saturation deficit, and dew point.

- Adjust air pressure measurements: Scale adjustment, temperature correction, and additional corrections. Normalize atmospheric pressure to sea level.

- Adjust wind measurements: Based on anemometer calibration documents to convert wind speed from rotations.

- Calculate various meteorological characteristics of each factor.

- Identify trends and variations of meteorological factors over time and space.

- Compile and report the results.

See more about Circular 31/2024/TT-BTNMT effective from January 27, 2025.

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