Circular No. 52/2005/TT-BNNMT on technical procedures for monitoring water resources and warning, forecasting water sources

CIRCULAR

Technical Regulations on Water Resource Monitoring and Early Warning, Forecasting

Pursuant to the Law on Water Resources dated November 27, 2023;

Pursuant to Decree No. 35/2025/NĐ-CP dated February 25, 2025 of the Government stipulating the functions, tasks, powers, and organizational structure of the Ministry of Agriculture and Rural Development;

Pursuant to Decree No. 53/2024/NĐ-CP dated May 16, 2024 of the Government detailing implementation of certain provisions of the Law on Water Resources;

At the proposal of the Director of the National Water Resources Management Agency;

The Minister of Agriculture and Environment promulgates this Circular stipulating technical regulations on water resource monitoring and early warning, forecasting.

PART I

GENERAL PROVISIONS

Article 1. Scope of Regulation

This Circular stipulates technical regulations on water resource monitoring and early warning, forecasting for surface water and groundwater as prescribed by laws on water resources.

Article 2. Applicability

This Circular applies to agencies, organizations, and individuals related to water resource monitoring activities and early warning, forecasting of water sources as prescribed by laws on water resources.

Article 3. General Requirements for Water Resource Monitoring and Early Warning, Forecasting

1. Water resource monitoring must ensure regular and timely provision of information and data on water levels, flow rates, and water quality to serve purposes of early warning, forecasting water sources, and requirements of water resource management work.

2. Early warning and forecasting of water sources shall be carried out using one or more methods (analytical; statistical; modeling). Results of early warning and forecasting of water sources shall be compiled by river basin, sub-basin, sub-region within the integrated river basin planning, administrative scope of provinces and centrally governed cities, and at locations designated for early warning and forecasting of water sources.

3. Information and data from water resource monitoring must be managed, stored, updated into the National Water Resources Information System and database, and ensure provision and sharing to serve early warning and forecasting of water sources. Forms of information transmission and sharing must be appropriate for the recipients and information infrastructure.

4. The chain of information and data serving water source forecasting must ensure a minimum of twenty years. In cases where there is less than twenty years, appropriate methods to extend the data should be implemented based on specific conditions.

5. Early warning and forecasting bulletins must ensure timely and accurate provision of information about the status, trends, and unusual developments of water sources to help water resource management authorities and the public take effective response measures.

Chapter II

TECHNICAL REGULATIONS ON WATER RESOURCE MONITORING

Article 4. Procedures and Contents of Water Resource Monitoring

1. Water resource monitoring is conducted through automatic continuous monitoring; periodic monitoring (semi-automatic; self-recording; manual). For points, stations, facilities established after the effectiveness of this Circular, the following procedures and contents shall be implemented:

a) Determine the purpose of monitoring;

b) Determine the location of monitoring;

c) Determine parameters, monitoring regime, and frequency for each parameter;

d) Determine the form and method of monitoring;

đ) Install monitoring equipment;

e) Develop a monitoring plan;

g) Conduct monitoring for each parameter;

h) Compile, evaluate, adjust, process, and update monitoring data for early warning and forecasting of water sources;

i) Prepare reports on monitoring results and statistical indicators;

k) Manage, store, provide, share monitoring results, and update monitoring results into the National Water Resources Information System and database.

2. In cases where monitoring is conducted at existing monitoring points, stations, and facilities with installed equipment, the contents specified in points e, g, h, i, and k of Clause 1 of this Article shall be implemented.

Article 5. Determining the Purpose of Monitoring

1. Water resource monitoring aims to provide information and data on water levels, flow rates, and water quality for the following purposes:

a) Forecasting water resources in accordance with laws on water resources;

b) Warning about droughts, water shortages, depletion, and decline in water levels; pollution, degradation of water quality, and saltwater intrusion as stipulated by laws on water resources;

c) Serving management requirements for water resources.

2. Based on the monitoring purposes specified in Clause 1 of this Article, competent authorities shall consider and decide specifically on the monitoring purposes for each point, facility, and monitoring station, and select appropriate parameters, frequency, methods, and regimes of monitoring.

Article 6. Determining the Location of Monitoring

Based on the purpose of water resource monitoring as stipulated in Article 5 of this Circular, the location of monitoring is determined as follows:

1. The determination of surface water level monitoring locations is carried out according to the provisions of Section 2.1.2, and flow rate monitoring locations according to the provisions of Section 2.3.2 of the Technical Regulation QCVN 47:2022/BTNMT issued together with Circular No. 22/2022/TT-BTNMT dated December 20, 2022 of the Minister of Natural Resources and Environment (hereinafter referred to as QCVN 47:2022/BTNMT), ensuring the main requirements as follows: representing the flow regime of the river section, meeting the monitoring purpose; the river section where the monitoring route is set up should be relatively straight, facilitating the arrangement of monitoring stations and facilities; ensuring stability, longevity, and safety for installation, operation, maintenance, and repair.

2. The determination of underground water resource monitoring locations and aquifer layers ensures the main requirements as follows: representativeness and typicality for the region, area, and aquifer layer; reflecting changes in underground water levels and quality, meeting the monitoring purpose; easy to implement monitoring and maintain equipment; avoiding areas at risk of landslides, flash floods, and security risks; ensuring long-term stability; distances between points and facilities suitable for the monitoring purpose and aquifer layer.

3. Based on the provisions of Clauses 1 and 2 of this Article, competent authorities shall choose monitoring locations to develop plans, tasks, and programs involving water resource monitoring activities that align with the monitoring purposes specified in Article 5 of this Circular.

In cases where monitoring locations are determined in the overall plan for basic investigation of water resources, they shall be implemented according to the plan. For monitoring aimed at supervising water extraction and use, current regulations shall apply.

Article 7. Determining Parameters for Water Resource Monitoring

1. Parameters for surface water resource monitoring:

a) Flow rate and water level as prescribed by laws on meteorology and hydrology;

b) Parameters for measuring and analyzing surface water quality, including: pH, Dissolved Oxygen (DO), Total Suspended Solids (TSS), Chemical Oxygen Demand (COD), Biochemical Oxygen Demand (BOD), Total Nitrogen, Total Phosphorus, Total Coliform, Chloride, and other parameters specified in Clause 3 of this Article.₅Total Nitrogen, Total Phosphorus, Total Coliform, Chloride, and other parameters prescribed in Clause 3 of this Article.

2. Parameters for underground water resource monitoring:

a) Water level at observation wells, flow rate at springs;

b) Parameters for measuring and analyzing underground water quality, including: pH, Ammonia (NH₄⁺ calculated as Nitrogen), Nitrate (NO₃^- calculated as Nitrogen), Nitrite (NO₂^- calculated as Nitrogen), Permanganate Index, Total Dissolved Solids (TDS), Total Coliform, Hardness, Arsenic, Chloride, Iron, Manganese, and other parameters specified in Clause 3 of this Article.

3. Based on current technical standards, and the monitoring purpose, competent authorities shall consider and decide to supplement other parameters as necessary to comply with the provisions of Article 5 of this Circular and specific characteristics of water sources and aquifer layers.

Article 8. Determining Monitoring Regimes and Frequencies

1. Monitoring regimes and frequencies for surface water resources at monitoring stations:

a) Manual water level monitoring regime shall be carried out in accordance with the provisions of Section 1.1.2 of Appendix A of Technical Regulation QCVN 47:2022/MONRE, wherein at least twice daily (at 07 hours and 19 hours) during the dry season for non-tidal rivers.

b) Automatic water level monitoring regime shall be conducted in accordance with the provisions of Section 1.1.5 of Appendix A of Technical Regulation QCVN 47:2022/MONRE, wherein during flood season, measurements are taken at least every five minutes, and during the dry season, at least every ten minutes; frequency of checking automatic water level measuring devices is twice a month, mid-month and end-of-month, applicable to stations with stable structures and normally functioning measuring devices, where the measured water level values differ by no more than ± 2 cm.

In cases where monitoring serves management requirements for water resources, the competent authority shall consider and decide in accordance with the laws on water resources.

c) Surface water flow monitoring regime in non-tidal areas shall be carried out in accordance with the provisions of Section 1.1 of Appendix B of Technical Regulation QCVN 47:2022/MONRE.

d) Surface water flow monitoring regime in tidal areas shall be carried out in accordance with the provisions of Section 2.1 of Appendix B of Technical Regulation QCVN 47:2022/MONRE.

đ) Surface water temperature monitoring regime shall be conducted simultaneously during the sampling process for surface water quality, with a minimum frequency of once a month.

e) Frequency of taking and analyzing field and laboratory samples for surface water quality shall be at least once a month; check samples shall be taken at least once per season.

2. Monitoring regimes and frequencies for groundwater resources at monitoring points and facilities:

a) Manual monitoring regime shall be conducted with a frequency of water level and flow monitoring at exposed aquifers five times a month on the 6th, 12th, 18th, 24th, and 30th days during the dry season, and ten times a month on the 3rd, 6th, 9th, 12th, 15th, 18th, 21st, 24th, 27th, and 30th days during the rainy season; for February, which does not have the 30th day, measurement shifts to the 1st of March.

b) Semi-automatic water level monitoring regime: data recording frequency is every two hours; data collection frequency is twice a month, mid-month and end-of-month; water level monitoring inspection frequency is twice a month using manual methods at the same time as data collection.

c) Automatic water level monitoring regime: data recording frequency is every two hours; office-based inspection through computer systems according to the frequency specified in point a of this clause; field inspections are conducted twice a month, mid-month and end-of-month.

d) Groundwater quality monitoring regime at monitoring points and facilities: at least twice a year during the dry and rainy seasons. Sampling for inspection shall be conducted at a minimum rate of 5% of the total number of samples.

3. For surface water and groundwater monitoring that does not fall under the provisions of Clause 1 and Clause 2 of this Article, the competent authority shall decide on the monitoring regime and frequency accordingly.

Article 9. Installation of Monitoring Equipment

1. Preparation and inspection of tools and equipment.

2. The installation of equipment shall be carried out according to the design and technical guidance of the monitoring equipment, calibration, and setting up the monitoring regime as required.

Article 10. Conducting Surface Water Level Monitoring

1. Manual surface water level monitoring shall be carried out in accordance with the provisions of Sections 1.2.1 and 1.2.2 of Appendix A of Technical Regulation QCVN 47:2022/MONRE, ensuring the following main contents:

a) Preparation and inspection of tools and equipment for monitoring.

b) Determination of water level readings at stakes or water gauges; if there is a stake or gauge change within the day, readings must be taken from adjacent stakes or gauges for verification. Observation and description of weather phenomena (direction of water flow, riverbed changes, wind direction, wave intensity), recording monitoring data and weather phenomena in the monitoring logbook.

c) Maintenance of monitoring tools and equipment, cleanup.

d) Calculation of water level value based on readings and stake height, comparison with previous measurements, statistical analysis of characteristic values, copying of data.

đ) Data calculation, plotting hourly water level process on a chart, checking the chart to identify abnormal points not following regular patterns.

e) Compilation, evaluation, adjustment, processing, and updating of monitoring data for early warning and water source forecasting.

2. Surface water level monitoring for checking self-recording equipment shall be carried out in accordance with the provisions of Section 1.2.3 of Appendix A of Technical Regulation QCVN 47:2022/MONRE, ensuring the following main contents:

a) Preparation and inspection of tools, materials, and equipment for monitoring.

b) Inspection of the condition of the monitoring facility, observation and description of weather phenomena (direction of water flow, riverbed changes, wind direction, wave intensity).

c) Checking the accuracy of measurement timing: the device clock differs from the standard clock by no more than ± 2 minutes/24 hours.

d) Measurement of water level to check the operation of the equipment, marking the monitoring check time on the diagram: draw a 1 cm long line and interrupt it (about 0.5 mm) during the check period.

đ) Recording the results of the monitoring check in the logbook and on the water level diagram. Record the monitoring time on the left side and the water level value on the right side of the time check line on the diagram.

e) Maintenance of the facility, measurement instruments, repair, replacement, and storage of spare parts.

g) Compilation, evaluation, adjustment, processing, and updating of monitoring data for early warning and water source forecasting.

3. Conducting automatic surface water level monitoring, including the following main contents:

a) Access to the monitoring data system, check the continuity of the data. If a malfunction is detected during monitoring due to equipment issues, handle the equipment malfunction according to Article 16 of this Circular.

b) Compilation, evaluation, adjustment, processing, and updating of monitoring data for early warning and water source forecasting.

4. Forms used during surface water level monitoring are specified in Form No. 01 and Form No. 02 issued together with this Circular.

Article 11. Implementation of surface water flow monitoring

1. Surface water flow monitoring shall be carried out in accordance with the provisions set forth in Section 1.2 of Appendix B of Technical Regulation QCVN 47:2022/BTNMT, ensuring the following main contents:

a) Preparation and inspection of monitoring tools and equipment;

b) Measurement of water level and observation of river surface conditions;

c) Determination of the distance from the bank edge on both right and left sides;

d) Installation and configuration of measuring devices;

đ) Measurement of water flow using the devices specified in Clauses 2, 3, and 4 of this Article;

e) Maintenance of measurement means, machines, and equipment;

g) Collection of monitoring tools and equipment;

h) Compilation, evaluation, adjustment, processing, and updating of monitoring data for early warning and forecasting of water resources.

2. Measurement of surface water flow using a velocity meter

The measurement of surface water flow using a velocity meter with a digital display shall be conducted in accordance with the provisions set forth in Section 1.2.2 of Appendix B of Technical Regulation QCVN 47:2022/BTNMT, ensuring the following requirements:

a) The measurement time of speed at one point using a velocity meter must not be less than 100 seconds;

b) When the velocity meter is mounted on a pole, the pole foot must be equipped with a base plate and kept vertical during measurement.

In cases where cables are used to suspend fish, the angle of cable deviation must be measured, the weight of the iron fish increased, or the cable changed to reduce the cable deviation angle. If the deviation angle exceeds 10º, calibration must be performed;

c) During low-water season, when the water flow speed is too small and cannot be measured by a velocity meter along the main line, an auxiliary line should be selected for speed measurement. Water level measurements must still be taken along the main line during auxiliary line speed measurement. Auxiliary lines must ensure there is no inflow or outflow of water volume;

d) During flood season, when the water flow speed fluctuates rapidly, the water flow speed can be measured according to the simple measurement method prescribed in Appendix B of TCVN 12636-8:2020 Meteorological and Hydrological Monitoring - Part 8;

đ) Compilation, evaluation, adjustment, processing, and updating of monitoring data for early warning and forecasting of water resources.

3. Measurement of surface water flow based on ultrasonic principle

The measurement of surface water flow based on the ultrasonic principle shall be carried out in accordance with the provisions set forth in Section 1.2.4 of Appendix B of Technical Regulation QCVN 47:2022/BTNMT and technical guidance of the measuring device, ensuring the following requirements:

a) Before measurement, the depth, maximum speed, and shape of the riverbed on both left and right sides, as well as any obstacles (if present), must be estimated to prepare the measurement plan and configure the machine settings;

b) Water levels must be monitored at the beginning and end of the measurement, and the starting and ending positions must be determined;

c) A trial measurement must be conducted before the formal measurement to calibrate the equipment as required;

d) The equipment must stabilize for 01 to 02 seconds before data collection begins, and during movement, the measuring device should align with the cross-section of the river;

đ) At least two consecutive measurements must be made, and the results of the area and water flow between the previous and subsequent measurements must be checked, with a difference not exceeding ± 5%;

e) Compilation, evaluation, adjustment, processing, and updating of monitoring data for early warning and water source forecasting.

4. Measurement of surface water flow using fixedly installed automatic equipment

The measurement of surface water flow using fixedly installed automatic equipment shall be carried out in accordance with the provisions set forth in Section 1.2.5 of Appendix B of Technical Regulation QCVN 47:2022/BTNMT, ensuring the following requirements:

a) The installation location of the equipment should be chosen in the main stream area, allowing the determination of total cross-sectional water flow according to the purpose and requirements;

b) The measurement results of water flow using fixedly installed automatic equipment must be evaluated by comparing them with the actual total cross-sectional water flow, with a minimum of 30 measurements evenly distributed across different water levels (low, medium, high). At least 90% of the comparisons must not differ by more than ± 10%. Access to the monitoring data system must be made to check the continuity of the data. In case of monitoring issues caused by equipment, equipment malfunction handling must be carried out in accordance with Article 16 of this Circular;

c) Compilation, evaluation, adjustment, processing, and updating of monitoring data for early warning and forecasting of water resources.

5. Forms used during the process of surface water flow monitoring are stipulated in Form No. 03 and Form No. 04 attached to this Circular.

Article 12. Implementation of Water Quality Monitoring

1. The surface water quality monitoring as specified in Point b Clause 1 Article 7 of this Circular shall be carried out as follows:

a) Preparing equipment, materials, tools, and machinery, devices;

b) Collecting, preserving, and transporting samples in accordance with the provisions at Point a Section 1 Appendix 2.2 Circular No. 10/2021/TT-BTNMT dated June 30, 2021 issued by the Minister of Natural Resources and Environment on environmental monitoring techniques and management of monitoring information and data (hereinafter referred to as Circular No. 10/2021/TT-BTNMT);

c) Measuring and analyzing water quality at the site in accordance with the provisions at Point b Section 1 Appendix 2.2 Circular No. 10/2021/TT-BTNMT, and in the laboratory in accordance with the provisions at Section 2 Appendix 2.2 Circular No. 10/2021/TT-BTNMT;

d) Disassembling, cleaning up, and maintaining tools and equipment;

đ) Compilation, evaluation, adjustment, processing, and updating of monitoring data for early warning and forecasting of water resources.

2. The forms used during surface water quality monitoring are stipulated in Forms No. 05, Form No. 06, Form No. 07, Form No. 08, and Form No. 16 attached to this Circular.

Article 13. Implementation of Groundwater Level Monitoring

1. Manual monitoring includes:

a) Preparation and inspection of monitoring tools and equipment;

b) Inspecting the current status of monitoring points, structures, and observing weather conditions; taking photos of monitoring points and structures when there are unusual signs;

c) Unlocking and opening the structure's cover, conducting at least two minimum water level measurements, recording the average value of the two measurements in the monitoring logbook, if the difference between the two measurements exceeds 2 cm, re-measure from the beginning; recording the measurement results in the monitoring logbook;

d) Closing the structure's cover, locking, and cleaning up monitoring tools;

đ) Cleaning the monitoring point, concluding the field monitoring process;

e) Compilation, evaluation, adjustment, processing, and updating of monitoring data for early warning and water source forecasting.

2. Semi-automatic monitoring includes:

a) Preparing and checking tools and equipment;

b) Inspecting the current status of monitoring points, structures, and observing weather conditions; taking photos of monitoring points and structures when there are unusual signs;

c) Unlocking and opening the structure's cover, removing the automatic recording device from the well; performing regular maintenance of monitoring tools and equipment according to the plan for measuring devices;

d) Connecting and checking the operational status of the automatic recording device, backing up monitoring data from the automatic recording device to storage devices;

đ) Conducting manual water level measurements, recording in the monitoring logbook, comparing the automatic recorded values with manual measured values. In case of detection of malfunctions during monitoring due to equipment issues, handle the equipment malfunction in accordance with Article 16 of this Circular;

e) Reinstalling the automatic recording device if the measurement mode changes;

g) Returning the automatic recording device to the well;

h) Closing the structure's cover, locking, and cleaning up monitoring tools;

i) Cleaning the monitoring point, concluding the field monitoring process;

k) Summarizing, evaluating, adjusting, processing, and updating monitoring data for early warning and forecasting water resources;

3. Automatic monitoring includes:

a) Access to the monitoring data system, check the continuity of the data. If a malfunction is detected during monitoring due to equipment issues, handle the equipment malfunction according to Article 16 of this Circular.

b) Compilation, evaluation, adjustment, processing, and updating of monitoring data for early warning and water source forecasting.

4. The forms used during groundwater level monitoring are stipulated in Forms No. 09 and Form No. 10 attached to this Circular.

Article 14. Implementation of Flow Rate Monitoring at Surface Outlets

1. Monitoring using a weir board includes:

a) Preparation and inspection of monitoring tools and equipment;

b) Inspecting the current status of monitoring points, structures, and observing weather conditions; taking photos of monitoring points and structures when there are unusual signs;

c) Installing and calibrating the weir board;

d) Measuring the height of the water column flowing over the weir board with accuracy to millimeters, measuring at least three times and taking the average value to record in the monitoring logbook, if the difference between two measurements exceeds 5 mm, re-measure from the beginning;

đ) Calculating to determine the flow rate of surface outlets: for triangular weirs, calculate according to the formula Q = 0.014h²√h; for rectangular weirs, calculate according to the formula Q = 0.018bh√h; for trapezoidal weirs, calculate according to the formula Q = 0.0186bh√h (where: h is the water level height before the weir edge in cm, b is the width of the lower edge of the weir in cm, Q is the flow rate measured by the weir in liters/second);

e) Cleaning up monitoring tools, cleaning the monitoring point, concluding the field monitoring process;

g) Compilation, evaluation, adjustment, processing, and updating of monitoring data for early warning and water source forecasting.

2. Monitoring using a volumetric tank includes:

a) Preparation and inspection of monitoring tools and equipment;

b) Inspecting the current status of monitoring points, structures, and observing weather conditions; taking photos of monitoring points and structures when there are unusual signs;

c) Installing and calibrating the volumetric tank;

d) Determining the flow rate using a volumetric tank, the measured value must be the average of at least three measurements, the error of the three measurements must not exceed 5%, the volumetric tank must have a suitable capacity to ensure that the filling time does not exceed 30 seconds;

đ) Cleaning up monitoring tools, cleaning the monitoring point, concluding the field monitoring process;

e) Compilation, evaluation, adjustment, processing, and updating of monitoring data for early warning and water source forecasting.

3. The forms used during flow rate monitoring at surface outlets are stipulated in Forms No. 11 and Form No. 12 attached to this Circular.

Article 15. Implementation of groundwater quality monitoring

1. The groundwater quality monitoring as stipulated in point b, Clause 2, Article 7 of this Circular shall be carried out as follows:

a) Preparing equipment, materials, tools, and machinery, devices;

b) Measure the depth and water level of the drilled well;

In case the filter pipe is clogged by more than 70%, it must be cleaned by pumping according to the provisions of Article 17 of this Circular before sampling;

In case the filter pipe is clogged by less than 70%, clean pumping with a minimum volume of three times the column water volume in the drilled well shall be conducted. During the pumping process, measure the pH and EC indices until three consecutive stable readings are obtained, with intervals between each continuous stable reading not less than five minutes before sampling;

c) Collect, store, and transport water samples according to the provisions of point a, Section 1, Appendix 2.3 of Circular No. 10/2021/TT-BTNMT;

d) Conduct field measurements and analyze water quality according to the provisions of point b, Section 1, Appendix 2.3 of Circular No. 10/2021/TT-BTNMT, and laboratory analysis according to the provisions of Section 2, Appendix 2.3 of Circular No. 10/2021/TT-BTNMT;

đ) Dismantle and collect tools and equipment; maintain tools and equipment;

e) Compilation, evaluation, adjustment, processing, and updating of monitoring data for early warning and water source forecasting.

2. Forms for groundwater quality monitoring during the process are specified in Forms No. 05, No. 06, No. 07, No. 08, No. 13, No. 14, No. 15, No. 16, No. 17, and No. 18 attached to this Circular.

Article 16. Handling incidents in water resource monitoring

1. In case an incident caused by measuring equipment is detected for automatic or semi-automatic methods, handle the incident according to the provisions of Clause 2 of this Article. During the incident handling period, manual measurement shall be conducted at a frequency of five times/month on days 6, 12, 18, 24, and 30, except for February, which does not have day 30, then measure on day 1 of March. If required by management work, the competent authority may decide on a different monitoring frequency suitable for specific conditions.

2. Incident handling includes:

a) Preparation and inspection of monitoring tools and equipment;

b) Inspect the current status of the monitoring points and stations, check the equipment, power supply, and signal transmission, and observe weather conditions; take photos of the monitoring points and stations and record the incident in a report;

c) Backup monitoring data from the recording device to the storage device (if available); replace parts, repair, and restore the equipment; reinstall the equipment to ensure connection and normal operation;

d) Calibrate the equipment by reading the measured data from the device and comparing the recorded results with manual measurement results to ensure consistency between the device's measurement results and manual measurement;

đ) Clean the monitoring points and stations, conclude the incident handling process.

3. When an incident caused by monitoring equipment is detected, the monitor shall promptly prepare an incident report and report to the leadership of the monitoring unit. The unit assigned the monitoring task must implement measures to comply with the incident handling regulations stipulated in Clauses 1 and 2 of this Article.

Article 17. Pumping and cleaning of monitoring facilities

1. Pumping and cleaning of monitoring facilities shall be carried out as follows:

a) Regularly every five years;

b) When the filter pipe is clogged by more than 70%;

2. The pumping and cleaning of monitoring facilities shall be conducted according to the provisions of Article 6 of Circular No. 08/2015/TT-BTNMT dated February 26, 2015, issued by the Minister of Natural Resources and Environment, concerning technical specifications for pumping water tests in groundwater investigation and assessment.

Article 18. Compilation, evaluation, adjustment, correction, processing, and updating of monitoring data for water resource warning and forecasting

1. Compilation and processing of monitoring data.

2. Adjustment and correction of monitoring data:

a) Checking, standardizing data; identifying and reporting abnormal data, marking suspicious cases;

b) Comparing monitoring results with maximum, minimum, and long-term average extreme values to identify and determine the causes of abnormal values; drawing multi-year monitoring data series charts to detect abnormal values; drawing correlation charts between monitoring data and series data from other stations with hydraulic relationships (if applicable);

c) Evaluating monitoring results, determining error causes; analyzing correlations between data and influencing factors; assessing the completeness of data;

d) Calibrating, adjusting, and correcting to standardize data.

3. Correction of water quality monitoring data:

a) Checking, processing, standardizing data; identifying and reporting abnormal data, marking suspicious cases;

b) Evaluating statistical characteristics of water quality indicators as required;

c) Comparing and evaluating primary sample and check sample results;

d) Evaluating monitoring results, finding error causes; analyzing correlations between data and influencing factors; assessing the completeness of data.

4. Updating monitoring data for water resource warning and forecasting.

5. Preparing reports on the compilation, evaluation, adjustment, correction, processing, and updating of monitoring data for water resource warning and forecasting according to Model No. 19 issued together with this Circular.

Article 19. Preparation of monitoring result reports and statistical index reports

1. Preparing comprehensive monitoring result reports according to Model No. 20 issued together with this Circular.

2. Preparing statistical index reports for water resources monitoring indices according to Model No. 21 issued together with this Circular and regulations on statistical indices of natural resources and environment sector.

Article 20. Management, storage, provision, sharing of monitoring results and updating monitoring results into the National Water Resources Information System and Database

1. Management, storage, and updating of monitoring results:

a) Agencies and units responsible for monitoring tasks must store complete monitoring results in digital files and printed copies (if available), regularly back up; extract in table and chart formats; manage and display data;

b) The retention period for monitoring results shall be carried out in accordance with legal provisions;

c) Monitoring data must be updated regularly, promptly, and accurately into the National Water Resources Information System and Database as prescribed.

2. Provision and sharing of monitoring results:

a) Water resources monitoring data is provided and shared in written and electronic file formats;

b) Accessing and using water resources information and data must comply with legal provisions on access to information and related laws.

Chapter III

TECHNICAL PROVISIONS FOR WATER RESOURCE WARNING AND FORECASTING

Article 21. Procedures and contents for implementing water resource warning and forecasting

1. Basic steps for implementing water resource forecasting:

a) Determining the purpose of water resource forecasting;

b) Determining the parameters and forecast periods for water resources;

c) Implementing water resource forecasting according to one or more methods specified in Articles 24, 25, and 26 of this Circular depending on specific conditions;

d) Building water resource forecasting results.

2. Steps for building warning and forecasting bulletins:

a) Conducting forecasts as stipulated in point c, Clause 1 of this Article and forecast periods as stipulated in point d, Clause 2 of Article 23 of this Circular;

b) Compiling forecast results and monitoring data on water resources within the warning and forecasting scope to serve the prediction of water resource trends and determination of warning areas;

c) Identifying regions, areas, and locations at risk of drought, water shortage, depletion, and decline in water levels, pollution, degradation in water quality, and saline intrusion based on the results of implementation as stipulated in point a of this clause or monitoring flow rates, water levels, and water quality through monitoring and surveillance activities;

d) Editing warning and forecasting bulletins.

Article 22. Determining the purpose of water resource forecasting

Water resource forecasting in accordance with laws on water resources shall serve one of the following purposes:

1. Providing information on the trend of quantity and quality changes in water resources to develop water resource scenarios for river basins, plans for water exploitation and utilization, and schemes for water resource regulation and distribution.

2. Developing strategies and overall plans for basic surveys of water resources, and plans for water resources.

3. Serving decisions on the operation of interconnected reservoirs in river basins.

4. Warning about droughts, water shortages, depletion, and decline in water levels, pollution, degradation in water quality, and saline intrusion as prescribed by laws on water resources.

5. Other purposes serving basic surveys of water resources, the construction of warning and specialized forecasting bulletins on water resources for water resource management activities as required by competent state agencies.

Article 23. Determining parameters and forecast periods for water resource forecasting

1. Parameters for water resource forecasting include:

a) Water level;

b) Water volume;

c) Water quality.

2. Forecast periods for water resources according to laws on water resources are as follows:

a) For developing water resource strategies: maximum forecast period of 50 years, maximum forecast time step of one month;

b) For developing overall plans for basic surveys of water resources and plans for water resources: maximum forecast period of 30 years, maximum forecast time step of one month;

c) For developing plans for water exploitation and utilization, water resource scenarios, and schemes for water resource regulation and distribution: maximum forecast period of one year, monthly updates of forecasts (if applicable), maximum forecast time step of one month;

d) For serving decisions on the operation of interconnected reservoirs in river basins: maximum forecast period of one year, maximum forecast time step of one hour during flood season and one day during dry season;

đ) For developing warning and forecasting bulletins on water resources as stipulated in Clause 4 and Clause 5 of Article 22 of this Circular, including monthly, seasonal, annual, and specialized bulletins: maximum forecast period of one year, maximum forecast time step of one month.

Article 24. Water resource forecasting using modeling methods

1. Collecting and processing information and data for forecasting work:

a) Group of meteorological and hydrological information: rainfall, evaporation, temperature, water level, flow rate at meteorological, hydrological, and marine stations; unusual meteorological and hydrological phenomena or natural disasters directly affecting the quantity and quality of water in the river system to be assessed and forecasted;

b) Group of water resource characteristics: water level, flow rate, total surface water volume; number of rivers and water storage reservoirs; data on water quality, stored water volume in existing reservoirs; geological and hydrogeological well column data; groundwater level and quality monitoring data; data on water depletion, pollution, degradation, and saline intrusion caused by groundwater extraction within the warning and forecasting area;

c) Group of information and data on current water resource exploitation and wastewater discharge: name of facility, administrative location, type of water extraction/wastewater discharge facility; source of water extracted/receiving wastewater source; purpose of water use/discharge; estimated water extraction volume; irrigated area, aquaculture area, power generation capacity, number of households supplied with water; operational mode, regime, procedure, and operational data for water extraction/wastewater discharge;

d) Group of cross-section river data, topographic maps, geological maps, hydrogeological maps, water resource maps;

đ) Group of other related information;

e) Requirements for collected information and data: ensuring consistency with project objectives; surface water monitoring data must be at least 20 years; topographic, meteorological, hydrological, and river cross-section data must meet the warning and forecasting purposes under laws on water resources.

2. Analyzing and evaluating the current status of changes: total rainfall, water level, flow rate, total surface water volume, surface water quality at monitoring stations over the forecast period, compared to the same period in previous years; changes in groundwater levels and quality over the forecast period.

3. Conducting forecasts:

a) Inputting model data, establishing model structure;

b) Running the model, calibrating parameters by comparing calculated results with historical data. The model is suitable for forecasting when the maximum permissible error is ±20%;

c) Validating the model. The validation result is suitable for forecasting when the maximum permissible error is ±20%;

d) Calculating forecasts;

đ) Compiling forecast results.

4. Discussing, analyzing, and selecting forecast results.

5. Building forecast results.

Article 25. Water resource forecasting using statistical methods

1. Collecting and processing information and data of parameters to be forecasted according to the groups of data specified in points a, b, and c Clause 1 Article 24 of this Circular and meeting the requirements for collected information and data as stipulated in point e Clause 1 Article 24 of this Circular.

2. Analyzing and evaluating the current status of changes: total rainfall, water level, flow rate, total surface water volume, surface water quality at monitoring stations over the forecast period, compared to the same period in previous years; changes in groundwater levels and quality over the forecast period.

3. Conducting forecasts:

a) Statistical data analysis: calculating average value, maximum, minimum, standard deviation, coefficient of variation, checking probability distribution, analyzing temporal trend changes;

b) Calibration and verification. Calibration results are suitable for forecasting when the maximum allowable error is ±20%;

c) Conducting forecasts;

d) Editing forecast results.

4. Discussing, analyzing, and selecting forecast results.

5. Building forecast results.

Article 26. Water resource forecasting using analytical methods

1. Collecting and processing information and data of parameters to be forecasted according to the groups of data specified in points a, b, and c Clause 1 Article 24 of this Circular and meeting the requirements for collected information and data as stipulated in point e Clause 1 Article 24 of this Circular.

2. Analyzing and evaluating the current status of changes: total rainfall, water level, flow rate, total surface water volume, surface water quality at monitoring stations over the forecast period, compared to the same period in previous years; changes in groundwater levels and quality over the forecast period.

3. Forecasting includes:

a) Analyzing direct and indirect variables (input variables) affecting the parameters to be forecasted;

b) Establishing analytical relationship expressions, building mathematical function formulas (linear, nonlinear, power, integral...) representing the relationship between the parameters to be forecasted and input variables;

c) Evaluating results and calibration. Calibration results are suitable for forecasting when the maximum allowable error is ±20%;

d) Calculating and presenting forecast results;

đ) Compiling forecast results.

4. Discussing, analyzing, and selecting forecast results.

5. Building forecast results according to the selected option.

Article 27. Compiling water resource warning and forecasting bulletins

1. Based on the contents implemented as prescribed in points a, b, and c Clause 2 Article 21 of this Circular, compile water resource warning and forecasting bulletins according to Model No. 22 issued together with this Circular.

2. Water resource warning and forecasting bulletins shall be released before the 5th day of each month in one or more forms such as text and digital formats.

In case there are unusual developments regarding water resources, additional construction of water resource warning and forecasting bulletins shall be carried out as required by competent state agencies.

Chapter IV

IMPLEMENTING PROVISIONS

Article 28. Transitional Provisions

1. For monitoring stations and facilities for water resources monitoring that are currently implementing monitoring according to approved plans and tasks prior to the effective date of this Circular, continue to implement according to the regulations at the time of approval until completion.

2. Technical regulations on water resources monitoring, warning, and forecasting under water resources laws in other documents issued by the Ministry of Natural Resources and Environment or People's Committees of provinces and centrally-administered cities prior to the effective date of this Circular which differ from the provisions of this Circular shall be applied according to this Circular.

Article 29. Effective Date

1. This Circular takes effect from 10 the 10 2025.

2. Decision No. 19/2013/TT-BTNMT dated July 18, 2013 of the Minister of Natural Resources and Environment on technical regulations for groundwater monitoring becomes invalid from the date this Circular takes effect.

3. In cases where the legal normative documents cited for application in this Circular are amended, supplemented, or replaced, they will be applied according to the amended, supplemented, or replacement documents.

Article 30. Implementation

1. Ministries, ministerial-level agencies, government agencies, People's Committees at all levels, units under the Ministry of Agriculture and Environment, Departments of Agriculture and Environment of provinces and centrally-administered cities, and related organizations and individuals are responsible for implementing this Circular.

2. During the implementation process, if there are difficulties, timely reflect them to the Ministry of Agriculture and Environment for guidance or research for amendment and supplementation./.