What is the technical process of forecasting and warning of saltwater intrusion in Vietnam? What are the contents of the forecast and warning?
What is the technical process of saltwater intrusion forecasting and warning in Vietnam?
Pursuant to Clause 1, Article 3 of Circular 39/2016/TT-BTNMT, saltwater intrusion is the process of sea water encroaching into the mainland through the estuary due to the influence of tidal phenomenon, causing the river water to become salty.
According to that, the forecasting and warning of saltwater intrusion is carried out according to the technical process in Article 26 of Circular 25/2022/TT-BTNMT with the following contents:
(1) Collect and process all kinds of information and data.
- Collect monitoring data of rain factors, temperature in the basin, forecast area in the past period;
- Evolution of water level and flow of upstream stations in the forecasted basin and area in the past period;
- The tides in the basin, forecast area in the past period. Collect monitoring data of hydrographic stations that affect forecast and warning areas;
- Collecting information and data on operation of reservoirs and irrigation works in forecasted and neighboring areas;
- Collecting salinity measurement data at salinity measurement stations in the basin, forecast area and neighboring areas;
- Information and plan on projected water demand in the basin, forecast area, as well as demand for water use in agriculture, fisheries and other socio-economic activities (if any);
- Rain forecast broadcast for forecasting saline intrusion.
(2) Analysis and assessment of the current situation
- Analysis of weather changes: The change of rainfall and precipitation in space and time; rain forecast information on basins and regions within the forecast and warning period;
Hydrological analysis:
+ Analysis of changes in water level and flow in the basin and forecast area;
+ Analyze the impact of factors operating reservoirs, hydroelectric projects, irrigation works in the basin to the flow in the basin, forecast area; analyzing trends and developments of salinity intrusion, the highest salinity in the forecast area in the past period;
+ Analysis of the influence of tidal regime on the influence of saline intrusion;
+ Synthesize information to warn of dangerous phenomena such as high tide, sea level rise affecting the evolution of saline intrusion in the forecast area.
(3) Implement forecasting and warning plans
- Options used in forecasting and warning of saltwater intrusion in the national hydrometeorological forecasting and warning system: The plan is based on statistical methods; plans to use mathematical models (regression models, substance spread models); plans on the basis of other plans;
- Based on specific conditions, organizations and individuals that are not part of the national hydro-meteorological forecasting and warning system shall themselves stipulate the use of appropriate forecasting and warning plans.
(4) Discussion of forecasts and warnings
- Analyze and evaluate the reliability of forecast results by different methods used in the latest forecast broadcasts;
- Synthesize forecast results, initial warnings from different options and forecasters' comments;
- The person responsible for issuing the selection broadcast and making the final forecast conclusions ensures the reliability according to the forecast period.
(5) Building forecast and warning broadcasts
- The national hydrometeorological forecasting and warning system shall develop and issue broadcasts on forecasting and warning of saltwater intrusion according to regulations;
- Based on actual requirements, organizations and individuals that are not part of the national hydro-meteorological forecasting and warning system shall self-stipulate the content of the newsletter accordingly.
(6) Provide forecast and warning broadcasts
- The national hydro-meteorological forecast and warning system shall provide the forecast and warning messages of saltwater intrusion according to regulations;
- Organizations and individuals that are not part of the national hydro-meteorological forecasting and warning system shall themselves stipulate a list of addresses to be provided with broadcasts to suit actual requirements.
(7) Adding forecast and warning broadcasts
In case saltwater intrusion is detected with complicated developments, it is necessary to supplement the forecast and warning broadcasts in addition to the broadcasts issued as prescribed.
(8) Evaluation of the quality of forecasts and warnings
- National hydrometeorological forecasting and warning system: Assessing the complete and timely implementation of forecasting and warning of saltwater intrusion; assess the quality of broadcasts for forecasting and warning of saltwater intrusion. The evaluation of the quality of the broadcast on the forecast and warning of saltwater intrusion shall be carried out after having sufficient monitoring data according to the forecast period of the broadcast;
- Organizations and individuals that are not part of the national hydrometeorological forecasting and warning system must comply with current regulations on assessment of forecast quality.
What is the technical process of forecasting and warning of saltwater intrusion in Vietnam? What are the contents of the forecast and warning? (Image from the Internet)
What are the contents of the forecast and warning of saltwater intrusion in Vietnam?
Contents of forecasting and warning of saltwater intrusion are determined in Article 25 of Circular 25/2022/TT-BTNMT.
To be specific:
- Highest salinity, time of appearance at locations.
- Range and time affected by salinity 4‰ or 1‰.
- Distance affected by salinity 4‰ or 1‰ from the main river mouth.
- Level of disaster risk due to saline intrusion.
How often and when is the saltwater intrusion warning broadcast produced?
According to Article 27 of Circular 25/2022/TT-BTNMT and Clause 3, Article 19 of Decision 18/2021/QD-TTg, saltwater intrusion warning broadcast shall be produced upon detecting probability of saltwater intrusion in warning area. The first saltwater intrusion forecast broadcast shall be produced upon detecting saltwater intrusion in forecasted area.
After producing the first broadcast, subsequent saltwater intrusion forecast and warning broadcasts shall be produced once every 10 days on the 10th, 20th and the last day of every month; in complicated cases, additional broadcasts shall be produced in-between official broadcasts.
Circular 25/2022/TT-BTNMT takes effect from March 15, 2023.
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