Circular No. 97/2025/TT-BNNMT stipulates technical procedures for investigation, establishment of current status maps, risk zone maps due to landslides and flash floods at scales of 1:10,000 and 1:2,000.

Chapter I.

GENERAL PROVISIONS

Article 1. Scope of Regulation

This Circular regulates technical procedures for investigations, establishment of current status maps, risk zone maps, and risk zones due to landslides and flash floods at a scale of 1:10,000 and technical procedures for investigations, establishment of current status maps, risk zone maps, and hazards due to landslides at a scale of 1:2,000.

Article 2. Applicability

This Circular applies to state management agencies; organizations and individuals conducting investigations, establishment of current status maps, risk zone maps, and risk zones due to landslides and flash floods.

Article 3. Explanation of Terms

In this Circular, the following terms are understood as follows:

1. Landslide (also called earth-rock slide) is a geological disaster phenomenon involving the movement of soil, rock, and debris from the slope down towards the bottom under the influence of gravity; landslides also include mudflows, slurry flows, debris flows, rock falls, and earth flows.

2. Flash flood is a sudden flood occurring on slopes and small mountain streams, characterized by strong currents often accompanied by mud and rocks, rapid rise and fall, causing significant damage.

3. Triggering factors for landslides and flash floods are elements affecting the slope and river basin, leading to slope instability and rock-soil failure, resulting in landslides or flash floods; triggering factors can be exogenous (rain, wind, waves, temperature, soil moisture, groundwater level, human activities) or endogenous (earthquakes, volcanic activity, uplift of the ground).

4. Vulnerability includes conditions determined by physical, social, economic, or environmental factors that increase the degree of damage to communities caused by landslides and flash floods.

5. Exposure level refers to the extent to which physical, social, economic, or environmental factors (risk-bearing elements) within areas at risk of landslides and flash floods are affected.

6. Landslide and flash flood risk refers to the possibility of landslides and flash floods occurring based on natural or human-induced factors that cause such phenomena in a specific area.

7. Landslide and flash flood hazard refers to the potential occurrence of landslides or flash floods in specific areas, potentially causing loss of life, property damage, disruption of infrastructure, economic and social activities, and environmental destruction.

8. Landslide and flash flood risk refers to the potential for losses or damages that may occur (loss of life, injury, property loss, impact on livelihoods or interruption of economic activities, or environmental destruction) due to landslides and flash floods.

9. Geospatial Artificial Intelligence (GeoAI): GeoAI (Geospatial Artificial Intelligence) is the integration of artificial intelligence (AI) and geographic information system (GIS) data to analyze, predict, and automate decisions related to location.

Article 4. Zoning of investigation areas

1. The degree of complexity of geological structure includes: the degree of complexity of primary rock types, characteristics of the distribution of weathered crusts; the degree of complexity of geological structure for investigation areas is divided into simple, moderate, complex, and very complex zones according to the provisions set out in Appendix I attached hereto.

2. The degree of difficulty of transportation is determined based on terrain features, topographic fragmentation, river networks, and transportation and population characteristics; zones are classified according to travel difficulty levels, divided into good, moderate, poor, and very poor levels according to the provisions set out in Appendix II attached hereto.

Article 5. Principles and sequence of conducting investigations to establish current status maps, hazard zoning maps, landslide risk zoning maps at scales of 1:10,000 and 1:2,000

1. Investigation work is carried out sequentially from preliminary to detailed stages, from surface to deeper layers.

2. Designing and implementing investigation methods comply with technical regulations, standards, and norms currently in effect at the time of application and follow a sequential order.

3. During the investigation process, phenomena such as landslides, flash floods, and other natural disasters and geological hazards appearing in the investigation area are collected.

4. The steps for establishing tasks to conduct investigations to create current status maps, hazard zoning maps, and landslide risk zoning maps are carried out in the following sequence:

a) Drafting the project proposal;

b) Implementing the construction of the project;

c) Preparing the final report;

d) Transferring results to local authorities;

đ) Archiving.

Article 6. Content of investigation work, establishment of current status maps, hazard zoning maps, and landslide risk zoning maps at scales of 1:10,000 and 1:2,000

1. Content of preliminary investigation work

a) Conducting preliminary surveys of the project proposal area;

b) Collecting basic information about landslides and flash floods through local authorities and current conditions, particularly in high-risk areas;

c) Taking samples, processing, and analyzing samples to supplement geological data;

d) Determining construction conditions for the project proposal to design appropriate methods and procedures.

2. Content of investigation work, establishment of current status maps, hazard zoning maps, and landslide risk zoning maps at a scale of 1:10,000

a) Collecting data on current landslide and flash flood conditions; geological-structural, tectonic-destructive belt; geomorphological-topographical; hydrogeological-engineering geological; weathered crust; geophysical data, excavation works; vegetation cover; meteorological-hydrological conditions and data; land use status, population, infrastructure, socio-economic conditions, and related materials;

b) Synthesizing, processing, and analyzing collected data and preliminary surveys (if any); creating diagrams, maps, geological cross-sections, and construction designs;

c) Updating and analyzing remote sensing images to supplement information and data;

d) Analyzing topographic factors from digital elevation models;

đ) Establishing current status landslide and flash flood maps at a scale of 1:10,000 from collected materials;

e) Investigating current landslide and flash flood conditions and geological characteristics; collecting information on causes, triggering factors, formation and development processes, and damages;

g) Surveying and delineating current landslide and flash flood conditions, potential landslide areas, and flash flood risk zones in the field;

h) Using unmanned aerial vehicles (UAVs) to conduct detailed surveys of topographic features, stream systems, erosion channels, cracks, and displacement zones to assess current conditions, risks, and risk zoning;

i) Preparing rapid reports during field investigations;

k) Excavating works (exposures, pits, trenches, wells);

l) Collecting, processing, and analyzing various types of samples;

m) Updating current status landslide and flash flood data and maps at a scale of 1:10,000;

n) Establishing slope stability models at a scale of 1:10,000 for high-risk objects or verifying landslide phenomena;

o) Creating various types of maps: current status maps; hazard zoning maps; disaster zoning maps, and landslide risk zoning maps;

p) Selecting safe areas to recommend preventive measures, resettlement, and solutions to reduce risks;

q) Promoting knowledge about landslides, flash floods, and other geological disasters; guiding signs of recognition, prevention skills, and response for local authorities and residents; simultaneously collecting information from the community.

3. Content of investigation work, establishment of current status maps, hazard zoning maps, and disaster zoning maps for landslides at a scale of 1:2,000

a) Not applying flash flood type at a scale of 1:2,000 (due to the wide scope of the watershed and survey area);

b) Carrying out tasks as stipulated in points a, b, c, d, đ, e, g, h, i, k, l, and n of Clause 2 of this Article (adjusted appropriately for a scale of 1:2,000);

c) Geophysical measurements (prioritizing electrical measurement methods, combining other methods when necessary);

d) Drilling;

đ) Field testing of hydrogeological and engineering geological characteristics;

e) Creating various types of maps: current status maps; hazard zoning maps; disaster zoning maps for landslides at a scale of 1:2,000.

Article 7. Investigation Network

1. Requirements

a) Investigate current conditions, establish maps and diagrams of components serving for risk zoning and landslide and flash flood hazard zoning to ensure comprehensiveness in the investigation area;

b) Ensure that no landslide or flash flood points that have occurred or are at risk of occurring are overlooked;

c) Collect sufficient and comprehensive specialized information;

d) Prioritize surveys in all residential clusters, key projects, main and important transportation networks;

đ) Survey areas with potential risks to residential areas;

e) In river basins at risk of flash floods, review and assess landslide risks for the entire basin;

2. Principle

a) Conduct investigations at a scale of 1:10,000 for areas (villages, hamlets, communes) at risk of landslides and flash floods;

b) During the investigation process, if large to very large landslide masses affecting social welfare, economy, and society are discovered, implement a denser network similar to the investigation at a scale of 1:2,000; provide a quick report and propose subsequent tasks;

c) Establish current status maps and risk zoning maps for landslides at a scale of 1:2,000 for each point and slope strip (consistent with influencing factors);

d) Conduct detailed investigations at a scale of 1:2,000 only for landslide points;

3. Investigation density according to complexity level and map scale

Article 8. Digital Conversion of Original Documentation

1. Original documentation of the work of establishing current status maps, risk zoning maps for landslides and flash floods at scales of 1:10,000 and 1:2,000 shall be established in digital form, fully reflecting information as prescribed in Circular No. 43/2016/TT-BTNMT dated December 26, 2016 of the Minister of Natural Resources and Environment on technical regulations for collecting and establishing original documentation in basic geological surveys and mineral exploration;

2. Tools, software, applications used must ensure full information collection, data reliability, and compatibility with the structure of the Ministry of Agriculture and Environment's database;

3. Organizations and individuals assigned to perform the task are responsible for retaining and updating digital information and data on devices as prescribed and ensuring synchronization with the National Database on Disaster Prevention and Control;

4. In cases where printing from updated digital files in the system database is necessary, permission is granted;

Article 9. Application of Technology

1. Aerial drone surveying work

a) Applied to difficult-to-access areas or large-scale landslide points and above;

b) From the results of aerial photography, provide a general description of current geological disaster conditions, topography, flow characteristics, vegetation cover, and the impact range of past landslide and flash flood events;

c) Take high-resolution images as reference materials;

d) The product is natural color orthophoto data, not overly bright or dark, without glare or cloud cover, investigation forms, and reports on aerial drone photography work; clear, without cloud cover, unmanned aerial vehicle photo survey investigation forms and reports;

đ) Aerial drone surveying techniques are implemented in accordance with Articles 14 and 15 of Circular No. 07/2021/TT-BTNMT dated June 30, 2021 of the Minister of Natural Resources and Environment on technical regulations for acquiring and processing digital aerial imagery data from drones for the construction and updating of the National Geographic Database at scales of 1:2,000, 1:5,000, and the creation of topographic maps at scales of 1:500, 1:1,000;

2. GeoAI

a) Applied in project establishment, image analysis; creating thematic maps, risk zoning for landslides and flash floods;

b) Input data includes project data sets comprising current geological disaster data, geological structure data, geological information, geological cross-sections, geochemical data, geophysical data, drilling projects, hydrogeological and engineering geological data, weathering crust, geomorphology, environment, meteorology and hydrology, infrastructure, and other related data (if necessary);

c) The application results of GeoAI technology are evaluated for reliability and verified in practice;

3. Other technologies

a) Other advanced technologies are detailed in specific project descriptions;

b) Evaluate the reliability and verify the results of technology application.

Article 10. Establishment, Review, and Approval of Proposals

1. The work of establishing, reviewing, and approving proposals shall be carried out in accordance with the provisions of Chapter II of Circular No. 33/2025/TT-BNNMT dated July 2, 2025, issued by the Minister of Agriculture and Rural Development on the establishment, review, and approval of proposals, projects, tasks, reports on the results of basic geological surveys, geological surveys on minerals, and the publication of the results of basic geological surveys.

2. Collection, compilation, and processing of materials for proposal establishment

a) Collecting and compiling materials related to landslides and other geological disasters in the research area, remote sensing data, current landslide conditions and other geological disasters, geological structure, tectonic zones, geomorphology, hydrogeological and engineering geological information, weathered crust, vegetation cover, meteorology, hydrology, current land use status, geophysical data, mining and excavation works, socio-economic and cultural characteristics of the survey area, and other relevant materials; updating periodic disaster reports from disaster prevention and control agencies at all levels; evaluating the current status, effectiveness, and limitations of implemented methods.

b) Conducting preliminary surveys in the proposal establishment area; collecting basic information about geological disasters through local authorities and current conditions, taking samples, and analyzing them to supplement geological materials, determine construction conditions for the proposal, and reasonably design methods and implementation sequences.

3. Processing remote sensing materials to delineate areas showing signs of landslides, flash floods, and other layers of information serving the proposal establishment process.

4. Establishing initial data for the proposal establishment process based on integration with the National Database on Disaster Prevention and Control.

5. Creating the following types of maps and diagrams:

a) Diagrams of the current state of geological disaster investigations, showing surveyed structures, related geological disasters, and surveyed areas.

b) Geological diagrams, showing geological formations and types of rocks capable of causing landslides and flash floods.

c) Current condition and landslide risk zoning maps, flash flood risk zoning maps that have been investigated in previous phases.

d) Construction design maps, showing planned investigation areas, construction conditions for each area, and planned construction sequences and times.

e) Other related maps and diagrams.

The coordinate system used in the proposal is the national coordinate system VN-2000 with the central meridian and three-degree projection.

Article 11. Establishment, Review, and Approval of Reports

1. The work of establishing, reviewing, and approving reports shall be carried out in accordance with the provisions of Chapter II of Circular No. 33/2025/TT-BNNMT dated July 2, 2025, issued by the Minister of Agriculture and Rural Development on the establishment, review, and approval of proposals, projects, tasks, reports on the results of basic geological surveys, geological surveys on minerals, and the publication of the results of basic geological surveys.

2. The final report of the proposal shall establish current condition maps, risk zoning maps, and risk assessment maps due to landslides and flash floods at scales of 1:10,000 and 1:2,000, fully reflecting the contents stipulated in Article 6 of this Circular.

3. Products of the proposal investigation, including current condition maps, risk zoning maps, and risk assessment maps due to landslides and flash floods at scales of 1:10,000 and 1:2,000, shall be implemented in accordance with the provisions of Article 8 of this Circular.

Article 12. Propaganda and dissemination work to promote knowledge about landslides and flash floods, and guidance on using materials transferred to localities

1. Content

a) Propaganda work to raise community awareness about geological disasters in general and landslides and flash floods in particular at the locality level;

b) Transfer of materials produced from the project;

c) Guidance on using reports, maps, and software;

d) Incorporating feedback from localities regarding transferred products to improve the report.

2. The target group includes local-level officials and specialized staff responsible for disaster prevention and control.

3. Products handed over to localities

a) Investigation results report; establishment of landslide and flash flood status maps at a scale of 1:10,000 and landslide status maps at a scale of 1:2,000 (if available);

b) Status maps of landslides and flash floods at a scale of 1:10,000 and accompanying explanatory notes;

c) Maps of risk zones for landslides and flash floods, and hazard maps for landslides and flash floods at a scale of 1:10,000;

d) Hazard maps for landslides at a scale of 1:2,000;

đ) Comprehensive digital data compiling investigation results, status maps, risk zone maps, and hazard maps for landslides and flash floods at scales of 1:10,000 and 1:2,000;

e) USB storage containing submitted digital documents (Word, Excel, PDF, Shapefile, open-source software).

Chapter II.

INVESTIGATION AND ESTABLISHMENT OF STATUS MAPS, ZONE RISK MAPS FOR LANDSLIDES AND FLASH FLOODS AT A SCALE OF 1:10,000DANGER ZONE, SLIDE AND DEBRIS FLOW HAZARD ZONING AT SCALE 1:10,000

Article 13. Office work before fieldwork at a scale of 1:10,000

1. Collection and synthesis of materials

a) Collection and synthesis of materials related to landslides, flash floods, and other geological disasters in the research area, remote sensing data, current status of landslides and flash floods, and other geological disasters; updating periodic disaster-related reports from disaster prevention and control agencies at all levels;

b) Collection and synthesis of geological structure, tectonic destruction belt, geomorphology, hydrogeological engineering geology, weathering crust, vegetation cover, meteorological and hydrological data, land use status, geophysical data, mining and excavation works; the latest topographic map at a scale of 1:10,000;

c) Collection and synthesis of socio-economic characteristics, cultural features, infrastructure in the survey area, and other relevant materials;

d) Establishment of various preliminary diagrams and drawings at a scale of 1:10,000 from collected and synthesized sources, including at least:

- Geological structure diagram;

- Tectonic destruction belt diagram;

- Geomorphology diagram;

- Hydrogeological engineering geology diagram;

- Weathering crust diagram;

- Current geological disaster status diagram;

- Land use status diagram;

- Population and infrastructure distribution diagram;

- Earthquake epicenter distribution diagram;

- River network diagram;

- River basin and sub-basin distribution diagram.

2. Updating and analyzing remote sensing images

Assessing the impact, determining parameters, standardizing, and classifying component maps to serve the establishment of risk zone maps for landslides and flash floods, including:

a) Vegetation cover classification map layer;

b) Vegetation cover changes over time;

c) Surface terrain changes;

d) Landslide and flash flood slide block boundaries and changes over time;

đ) Landslide and flash flood location diagram based on image analysis and accompanying database;

e) Updating population and infrastructure locations;

g) Detailed river network, flow obstruction points, and potential flash flood impact areas;

h) System of reservoirs and dams along rivers and streams.

3. Analysis of topographical factors from digital elevation maps

Assessing the impact of landslides and flash floods, determining parameters, standardizing information layers, and establishing component diagrams to serve the establishment of landslide and flash flood risk zone maps.

a) Slope gradient information layer;

b) Cross-sectional cutting depth information layer;

c) Vertical cutting depth information layer;

d) Terrain curvature information layer;

đ) Slope aspect information layer;

e) Topographic hierarchy information layer;

g) Lineament density information layer;

h) Sub-watershed division information layer.

4. Updating the project's database

a) Information layers from Clauses 1, 2, and 3 of this Article are converted and stored in digital form;

b) Maintained within the existing database serving the implementation of the project;

c) Database structure compatible with the National Disaster Prevention and Control Database.

Article 14. Collection of information on geological disasters at the local level

1. Contact work and collect information on land slides, flash floods, and other geological disasters in the investigation area from province to commune, village, and hamlet in sequence.

2. Organize training sessions with participation from local government levels and experienced individuals in the investigation area to disseminate signs of land slides, flash floods, and other geological disasters, and record occurrences of these phenomena within the local administrative region.

3. Seek opinions from local government levels regarding the possibility of occurrence of geological disaster phenomena generally and specifically land slides and flash floods; the feasibility of preventive measures.

4. Provide information on preventive measures already implemented in the region and local customs and traditions.

Article 15. Investigation of current land slide and flash flood conditions at a scale of 1:10,000

1. The investigation network is carried out according to the provisions stipulated in Article 7 of this Circular.

2. Conduct survey routes in the investigation area.

3. Along the described route, continuously document and fully collect contents on location; topographic and geomorphological characteristics; vegetation; hydrogeology and engineering geology; rock composition, stratigraphic division name; layering characteristics, fractures, crushing, lying position, degree of weathering, thickness of overburden, weathered layers; river and stream characteristics, slope, width, narrowing channel locations, reservoir and dam locations, riverbank structures; socio-economic factors; population distribution along streams and watersheds; detailed content collection is specified in investigation forms.

4. Investigate information on the current status of each land slide mass, old and newly formed flash floods, potential recurrence, areas at risk of land slides, locations of past flash floods, affected range, weather conditions, and corresponding rainfall patterns; detailed content collection is specified in investigation forms.

5. Investigate socio-economic information, statistics, and assess losses in terms of human life and property caused by land slides, flash floods, and related geological disasters; understand measures already and currently being implemented in localities aimed at preventing, avoiding, and mitigating the impacts of land slides, flash floods, and related geological disasters.

6. Identify and select safe areas, recommend sites for prevention and resettlement activities for residents.

7. Summarize the journey in compliance with existing regulations applicable at the time of geological investigation, clarify topographic and geomorphic features, geology, hydrogeology and engineering geology, weathering crust, current land slide and flash flood status, causes of occurrence; factors affecting land slides and flash floods, and propose remediation solutions.

8. Technical investigation forms on current land slide and flash flood status are conducted by technical staff specialized in geology and geological disasters; the content of technical investigation forms outside the field is defined in Appendix III and Appendix IV attached to this Circular; in some cases, additional information fields may be added to suit actual circumstances and approved along with project outline descriptions.

9. Community investigation forms on current land slide status are conducted by local residents and officials, supported by technical staff; the content of community investigation forms is defined in Appendix V attached to this Circular; in some cases, additional information fields may be added to suit actual circumstances.

10. Sociological investigation of socio-economic characteristics follows regulations issued by the General Statistics Office.

11. Field investigation work is conducted through electronic logs, collected information is designed similarly to investigation form templates; information is collected and stored on the main computer of the supervising agency and printed into a set of task products (if necessary).

Article 16. Excavation work for construction projects

1. Excavation work is carried out during the investigation phase, including clearing traces, trenches, pits, wells to clarify geological boundaries, tectonic destruction zones, weathered crusts, slip surfaces, landslides, monitoring, and sampling.

2. The excavation work for construction projects shall be implemented in accordance with the provisions of Circular No. 16/2020/TT-BTNMT dated December 18, 2020, issued by the Minister of Natural Resources and Environment on technical regulations for excavation work and geological and mineral sampling at excavation sites.

Article 17. Sampling, processing, and analysis of samples

1. Bulk samples

a) Taken for observation at survey points on the surface or exposed bedrock points;

b) Technical procedures for sampling shall be carried out in accordance with the provisions of Circular No. 16/2020/TT-BTNMT.

2. Weathered crust trench samples

a) Location: trench samples are taken from landslide slopes, cleared traces, trenches, pits, and wells within the affected soil and rock areas;

b) In cases where the conditions specified in point a of this clause are not met, they shall be taken at locations with similar geological objects, slope angles, and degrees of weathering closest to the designated sampling landslide point;

c) The number of samples must ensure representativeness for various geological objects (petrographic components), degrees of weathering (complete, strong, moderate), and slope gradient classes (0-8º, 8-15º, 15-25º, 25-35º, >45º);

d) Technical procedures for sampling shall be carried out in accordance with the provisions of Circular No. 16/2020/TT-BTNMT.

3. Soil mechanical property samples

a) Location: undisturbed soil mechanical property samples are taken from trenches, pits, and wells within the affected soil and rock areas but in intact sections;

b) In cases where the conditions specified in point a of this clause are not met, they shall be taken at locations with similar geological objects, slope angles, and degrees of weathering closest to the designated sampling landslide point;

c) Number of samples taken: one sample per layer (representative of weathering zones);

d) Sample size: samples are taken in dimensions of 20x20x20cm;

đ) Undisturbed soil mechanical property samples: soil samples for determining mechanical properties are taken according to National Standard TCVN 2683:2012 Construction Soil - Sampling, Packaging, Transport, and Preservation of Samples.

4. Rock mechanical property samples

a) Location: rock mechanical property samples are taken from collapsed rock faces, rolling rocks;

b) Number of samples: 1-2 representative samples for petrographic characteristics and degree of fracturing;

c) Sample size: 20x20x20cm.

5. Sample analysis

a) Analysis of trench samples: seven indicators are analyzed to classify weathered crusts: SiO₂, Fe (Fe₂O₃, FeO), Al₂O₃; K₂O; Na₂O, MKN;

b) Analysis of soil mechanical property samples: analysis of soil mechanical properties (minimum: bulk density (∆; g/cm³); internal friction angle (φ, degrees); cohesion force (C, kg/cm²) in different states;

c) Analysis of rock mechanical property samples: analysis of characteristic rock mechanical properties (minimum: bulk volume density (γ, g/cm³); internal friction angle (φ, degrees); cohesion force (C, kg/cm²);

d) Processing and analysis of samples shall be carried out in accordance with current regulations.

6. Other types of samples

a) Depending on the actual causes of landslides and flash floods, additional types of samples designed in the project description may be taken and analyzed;

b) Processing and analysis of samples shall be carried out in accordance with current regulations.

Article 18. Rapid reports during field investigations

1. Rapid reports during field investigations provide detailed descriptions of the current situation, mechanisms of landslide and flash flood occurrence, immediate risk levels, and recommendations for handling solutions.

2. The leading unit of the task signs, stamps, and sends the report to local authorities and management units as a basis for approval and adjustment of the task.

Article 19. Landslide and flash flood status map at a scale of 1:10,000 and base data set

1. Compilation and processing of field survey materials on current landslide and flash flood conditions, other geological hazards, geology, structure, tectonics, geomorphology, weathering crust, vegetation cover, hydrogeological and engineering geological conditions, civil infrastructure, sample collection and analysis results.

2. Preparation of thematic diagrams

a) Diagram of lithology components at a scale of 1:10,000;

b) Diagram of geomorphology and neotectonics at a scale of 1:10,000;

c) Diagram of structural tectonics and damage zones at a scale of 1:10,000;

d) Diagram of weathering crust at a scale of 1:10,000;

đ) Diagram of hydrogeological and engineering geological conditions at a scale of 1:10,000;

e) Diagram of human impact influence zone at a scale of 1:10,000;

g) Diagram of vegetation cover at a scale of 1:10,000;

h) Diagram of watershed slope and river network at a scale of 1:10,000;

i) Diagram of river watershed and sub-watersheds at a scale of 1:10,000;

k) Diagram of current land use at a scale of 1:10,000;

l) Diagram of current landslides, flash floods, and other geological hazards at a scale of 1:10,000;

m) Diagram of civil infrastructure at risk from landslides and flash floods at a scale of 1:10,000;

n) Diagram of safe areas for resettlement purposes;

o) Information on vulnerability to landslides and flash floods;

p) Diagrams showing other factors affecting the process of landslides and flash floods.

3. Content of the landslide and flash flood status map at a scale of 1:10,000

a) Topographic base map corresponding to the investigation scale;

b) Information on characteristic factors corresponding to Clause 2 of this Article and triggering factors constituting landslides, flash floods, and other geological hazards appearing in the investigation area (if applicable);

c) Locations and watersheds where landslides, flash floods, and other geological hazards have occurred or are likely to occur.

4. Completing the base data

a) Updating and supplementing the data established under Clause 4 of Article 13 of this Circular;

b) Standardizing geological hazard data from investigations, surveys, projects, current status maps, zoning, utilizing existing agricultural and environmental sector database structures designed from related tasks and projects to complete a database for the Project;

c) Adhering to the procedure for building natural resources and environment databases as stipulated in Circular No. 26/2014/TT-BTNMT dated May 28, 2014, issued by the Minister of Natural Resources and Environment on Procedures and Economic and Technical Standards for Building Natural Resources and Environment Databases, and Circular No. 14/2020/TT-BTNMT dated November 27, 2020, issued by the Minister of Natural Resources and Environment on Procedures and Economic and Technical Standards for Building, Maintaining, and Operating Information Systems in the Natural Resources and Environment Sector;

d) Database products are inspected and accepted according to the provisions of Circular No. 17/2016/TT-BTNMT dated July 19, 2016, issued by the Minister of Natural Resources and Environment on the issuance of Economic and Technical Standards for Inspecting and Accepting Information Technology Application Products in the Natural Resources and Environment Sector.

Article 20. Construction of Slope Stability Models at a Scale of 1:10,000

1. Representative models for typical objects with high landslide risks; representative of key controlling factors such as weathering crust types, slope angles, activating factors, or high-risk landslide points.

2. Scenario selection

Scenarios constructed in accordance with the characteristics of endogenous and exogenous factors affecting slopes, potential landslide points, or reconstructing landslide scenarios to determine influencing factors.

a) State of existence of material layers;

b) Groundwater level fluctuations;

c) Impact of load changes;

d) Impact of various forms of vibration;

đ) Other influencing factors (if any);

e) Input factors including extreme cases.

3. Product: report on implementation results and model; specifying selected cross-sections, input data, calculated scenarios, and achieved results clearly indicating safety levels and landslide risks.

Article 21. Establishment of landslide risk zoning maps and flash flood risk zoning maps at a scale of 1:10,000

1. Establishment of landslide risk zoning maps at a scale of 1:10,000

a) Requirements for zoning work: complete, accurate, and synchronized input data to ensure the reliability of the analysis model; zoning results must be verified for accuracy and clearly classified into up to five levels of risk (very low, low, medium, high, very high); the zoning map product should be visually clear and easy to recognize, supporting decision-making;

b) Establishment of landslide risk zoning data; input data according to Clause 2, Article 18 of this Circular; the amount of input data may vary depending on the characteristics of each area;

c) Implementation content: review, standardize, unify the structure and attributes of component map layers used as input data; assess the sensitivity of component factors to current landslides based on applying statistical methods, or equivalent; apply appropriate methods (frequency ratio, spatial multi-criteria evaluation, machine learning, artificial intelligence, etc.) suitable for collected data to build landslide risk zoning diagrams; a minimum of two methods must be applied; evaluate and verify the accuracy of the zoning method application results; determine the appropriate method based on the result of the most accurate zoning method; establish a zoning map that reflects different levels of landslide risk.

2. Establishment of flash flood risk zoning maps at a scale of 1:10,000

a) Method for constructing risk maps

Zoning based on flash flood potential index (FFPI)

FFPI = a₁₁×S + a₂₂×TWI + a₃₃×CI + a₄₄×G + a₅₅×T + a₆₆×LU + a₇₇×SPI

In which a₁₁, a₂₂,..., a₇₇are the weights of the components mentioned in Point b of this Clause and satisfy the condition: a₁₁+ a₂₂+ a₂₃+ a₂₄+ a₂₅+ a₂₆+ a₂₇=1.

b) Factors causing flash floods selected

c) Establishing a slope map: based on topographic maps at the same scale or larger than the survey scale, establish a slope map; classify slopes into 5 categories according to their distribution level (details of the levels specified in Table 1, Appendix VI);

d) Establishing a terrain wetness index map: based on topographic maps at the same scale or larger than the survey scale; study and establish a terrain wetness index map; classify the terrain wetness index into 5 categories according to their distribution level (details of the levels specified in Table 2, Appendix VI);

đ) Establishing a curvature map: based on topographic maps at the same scale or larger than the survey scale; study and establish a curvature map; classify curvatures into 5 categories according to their distribution level (details of the levels specified in Table 3, Appendix VI);

e) Establishing an erosion risk map: based on soil maps at the same scale or the closest scale to the survey scale; study and group soil types developed on various geological substrates and weathered crusts; establish an erosion risk zoning map; classify erosion risks into 5 categories (details of the levels specified in Table 4, Appendix VI);

g) Establishing a protective capacity zoning map for vegetation cover: based on vegetation cover maps at the same scale or the closest scale to the survey scale, implement grouping of forest protection according to levels from low to high, evaluate the role of water protection of different types of forests to divide the protective capacity of various vegetation covers in provinces; establish a protective capacity zoning map; classify the protective capacity of the cover layer into 5 categories (details of the levels specified in Table 5, Appendix VI);

h) Establishing a soil water holding capacity zoning map: content grouped according to the water holding capacity of vegetation cover from land use maps at the same scale or the closest scale to the survey scale, into 5 groups; establish a soil water holding capacity zoning map; classify land use according to its usage characteristics into 5 categories (details of the levels specified in Table 6, Appendix VI);

i) Establishing a stream power index zoning map: based on topographic maps at the same scale or larger than the survey scale; study and establish a stream power index map; classify the stream power index into 5 categories according to their distribution level (details of the levels specified in Table 7, Appendix VI);

k) Building a flash flood risk zoning map

Establish a flash flood potential index map according to the formula in Point a of Clause 2 of this Article; classify the flash flood potential index into 5 categories according to their distribution level (details of the levels specified in Table 8, Appendix VI); build a flash flood risk zoning map, delineating areas with risk levels (very low, low, medium, high, very high):

- Level 1: very low risk (unlikely to occur);

- Level 2: low risk;

- Level 3: medium risk;

- Level 4: high risk;

- Level 5: very high risk.

3. In addition to the methods mentioned in Clauses 1 and 2 of this Article, depending on the development level of science and technology, organizations and individuals assigned to perform the tasks may apply other advanced methods ensuring scientific validity, reliability, and verifiability, including but not limited to:

a) Applying artificial intelligence, machine learning, deep learning in spatial data analysis, remote sensing data, meteorological and hydrological data;

b) Applying GeoAI technology to integrate geological, geomorphological, meteorological and hydrological data and community data for risk prediction;

c) Applying numerical hydrological-hydraulic models to simulate flow and flash floods;

d) Applying IoT sensors, time-series data to calibrate and update risk maps;

đ) Other new technologies recognized by competent authorities, in accordance with national and international technical standards and regulations;

e) Methods described in detail in the explanatory notes approved by the competent authority.

4. Products

a) Report on data standardization work and assessment of the sensitivity of component factors;

b) Report on the results of landslide and flash flood risk zoning and warning.

c) A landslide risk zone warning map at a scale of 1:10,000 and accompanying descriptions;

d) The product identifies potential landslide slide masses and debris flow catchments in the area, providing detailed information on the location, size, and characteristics of areas at risk of landslides and debris flows to serve as input data for establishing a landslide risk zoning map.

Article 22. Establishing a Landslide Hazard Zoning Map at a Scale of 1:10,000

1. Requirements for Zoning Work

a) Input data from the zoning results carried out according to point a and point b of Clause 1, Article 21 of this Circular;

b) The product is a landslide hazard zoning map that shows risk factors such as landslide frequency and extent, helping to clearly identify high-risk areas prone to and affected by landslides.

2. Establishing Landslide Hazard Zoning Data, Input Data

a) A landslide risk zoning map;

b) Rainfall and seismic data;

c) Information on the time and extent of past landslide impacts;

d) Digital Elevation Model (DEM) data;

đ) Soil sample analysis results;

e) Results of applying slope stability models (expected slip surface diagrams);

g) Current status and statistical data on past landslide events' characteristics (in construction areas and nearby areas);

h) The amount of input data adjusted according to the characteristics of the area.

3. Implementation Content

a) Determine rainfall thresholds triggering landslides, prioritizing experimental methods with the following main steps:

- Collecting historical rainfall and landslide data (at least over a 30-year period);

- Identifying rainfall events causing landslides and analyzing pre-event and during-event rainfall amounts;

- Establishing minimum rainfall thresholds to trigger landslides based on the analysis of experimental events;

- Validating established rainfall thresholds by comparing them with actual landslide events and adjusting thresholds if necessary to increase accuracy.

b) Statistically analyze and assess the frequency and trends of extreme rainfall events (for recurrence periods up to 100 years):

- Collecting and processing rainfall data: gathering historical data (over a minimum 30-year period) from rain gauges within or near the investigation area; removing outliers, processing missing data, and checking data consistency;

- Determining predicted values and recurrence intervals: calculating recurrence intervals for extreme rainfall levels; predicting future extreme rainfall amounts for recurrence intervals of 2 years, 5 years, 10 years, 20 years, 30 years, 50 years, and 100 years;

- Determining future trends and frequencies of large rainfall events.

c) Determine the frequency and trends of seismic activity (for recurrence periods up to 100 years):

- Collecting historical earthquake data (at least 30 years), including time, location, intensity, and depth;

- Analyzing earthquake history: conducting statistical analysis to determine frequency, earthquake-prone areas, and recurrence cycles of major earthquakes;

- Applying earthquake risk prediction models to analyze and predict high-risk areas and assess earthquake trends over time (at least 100 years into the future).

d) Establish scenarios and corresponding data suitable for the selected model's input data and parameters:

- For statistical and experimental models: scenarios regarding the extent of sliding; expected hydrological condition scenarios;

- For physical models: expected slip surface scenarios; expected hydrological condition scenarios; scenarios for geotechnical parameters.

đ) In addition to the above methods, depending on the level of scientific and technological development, organizations and individuals assigned to carry out the task may apply other advanced methods ensuring scientific validity, reliability, and verifiability; new technologies recognized by competent authorities, consistent with national and international technical standards; methods described in detail in the approved explanatory notes.

g) Construct a landslide hazard zoning map at a scale of 1:10,000, delineating areas at five risk levels (very low, low, medium, high, very high) susceptible to landslide material impact.

4. Products:

a) Report on the preparation work for landslide hazard zoning data;

b) Report on the results of landslide hazard zoning;

c) A landslide hazard zoning map at a scale of 1:10,000 and accompanying descriptions.

Article 23. Establishment of flood hazard zoning maps at a scale of 1:10,000

1. Requirements for flood hazard zoning work

a) Input data from the zoning results carried out according to point a and point b of Clause 1, Article 21 of this Circular;

b) The flood hazard zoning map must clearly display elements that help identify high-risk areas for flash floods.

2. Establishing flood hazard zoning data, input data includes:

a) Previously established flood risk zoning maps;

b) Rainfall data;

c) Information on time and extent of impact from past flash floods;

d) Digital Elevation Model (DEM) data;

đ) Soil sample analysis results;

e) Results of applying slope stability models (expected slip surface diagrams);

g) Current status and statistical data on characteristics of past flash flood events (in the survey area and adjacent areas);

h) The amount of input data may vary according to the characteristics of the area.

3. Implementation Content

a) Determining rainfall thresholds triggering flash floods

- Collecting historical rainfall and flash flood data (at least over a 30-year period);

- Identifying rainfall events causing flash floods and analyzing rainfall before and during these events;

- Establishing minimum rainfall thresholds to trigger flash floods based on analysis of experimental events;

- Validating established rainfall thresholds by comparing them with actual landslide events and adjusting thresholds if necessary to increase accuracy.

b) Statistical analysis and assessment of frequency and trends of extreme rainfall events (for recurrence periods up to 100 years)

- Collecting and processing rainfall data: gathering historical data (over a minimum 30-year period) from rain gauges within or near the investigation area; removing outliers, processing missing data, and checking data consistency;

- Determining predictive values and recurrence intervals: calculating recurrence intervals for extreme rainfall values; predicting future extreme rainfall amounts for recurrence periods of 2 years, 5 years, 10 years, 20 years, 30 years, 50 years, and 100 years;

- Determining future trends and frequencies of large rainfall events.

4. In addition to the provisions stipulated in Clause 1 and Clause 2 of this Article, depending on the level of development of science and technology, organizations and individuals assigned to carry out the task may apply advanced methods ensuring scientific accuracy, reliability, and verifiability; new technologies recognized by competent authorities, consistent with national and international technical standards; detailed descriptions of such methods must be approved by the competent authority.

5. Products:

a) Report on data preparation work for flood hazard zoning;

b) Report on results of flood hazard zoning;

c) Flood hazard zoning map and accompanying explanatory notes.

Article 24. Establishment of landslide and flood risk zoning maps at a scale of 1:10,000

1. Requirements for landslide and flood risk zoning work at a scale of 1:10,000

a) Input data from the zoning results carried out according to point a and point b of Clause 1, Article 21 of this Circular;

b) Landslide and flood risk zoning maps at a scale of 1:10,000 must clearly depict risk levels from very low to very high, visually intuitive, easy to use, supporting preventive and response decision-making.

2. Establishing landslide and flood risk zoning data

a) Hazard zoning maps for landslides and floods;

b) Results of socio-economic and cultural surveys of the area: population distribution, average income per capita, infrastructure characteristics, disaster response capacity;

c) Other tangible and intangible assets.

3. Analysis and establishment of vulnerability zoning diagrams for landslide and flood risk zoning at a scale of 1:10,000

a) Social data analysis: information about the population (population density, age, education level), economy, health, standard of living, and factors related to community resilience to hazards;

b) Infrastructure data analysis: condition of public works, housing, transportation, electricity, water, and essential services;

c) Determining vulnerability indices and quantifying representative indices reflecting the degree of vulnerability such as:

- Economic factors: income, economic development of the region;

- Social factors: population distribution, poverty rate, health status, education.

d) These indices may differ depending on the type of hazard (landslide or flood);

đ) Spatial analysis: applying GIS tools to overlay layers of data (topography, population density, infrastructure) to determine areas with high vulnerability;

e) Categorizing and establishing vulnerability level diagrams: based on composite indices, dividing the area into five vulnerability levels: very low, low, medium, high, very high.

4. Analysis and establishment of exposure level zoning diagrams for landslide and flood risk zoning at a scale of 1:10,000

a) Collecting initial data on assets and infrastructure: statistics and listing of buildings, residences, production facilities, roads, schools, hospitals, and other public services;

b) Population data: number, distribution, population density, along with social factors such as income and health status:

- Spatial analysis: applying GIS tools to analyze spatial data, overlaying relevant asset and population information;

- Categorizing and establishing diagrams: based on completed analyses, dividing the area into five exposure levels: very low, low, medium, high, very high for people and the economy.

5. Construction of landslide and flood risk maps:

a) Applying GIS to synthesize results of landslide and flood hazard zoning maps, exposure level diagrams, vulnerability level diagrams, thereby creating an integrated map showing landslide and flood risk levels;

b) Classifying risk levels into five categories: very low, low, medium, high, very high;

c) Preparing reports on results and explanatory notes for landslide and flood risk maps.

6. Products:

a) Report on landslide and flood risk zoning results;

b) Landslide and flood risk zoning map at a scale of 1:10,000 and accompanying explanatory notes.

Chapter III.

ART. 25. FIELDWORK AT THE SCALE OF 1:2,000 IMPLEMENT IN ACCORDANCE WITH THE PROVISIONS OF ART. 13 OF THIS CIRCULAR, ADJUSTED TO THE SCALE OF 1:2,000;

ART. 26. GEODETIC WORK

1. USE TOPOGRAPHIC MAPS IN THE NATIONAL COORDINATE SYSTEM AT THE SAME SCALE AS THE DETAIL SURVEY OR A LARGER SCALE.

2. IF THERE IS NO TOPOGRAPHIC MAP AS PROVIDED FOR IN CLAUSE 1 OF THIS ARTICLE, A NEW TOPOGRAPHIC MAP SHALL BE ESTABLISHED IN ACCORDANCE WITH THE CURRENT EFFECTIVE REGULATIONS OF THE MINISTRY OF AGRICULTURE AND ENVIRONMENT ON THE ESTABLISHMENT OF TOPOGRAPHIC MAPS.

3. THE COORDINATE SYSTEM USED TO ESTABLISH TOPOGRAPHIC MAPS, CURRENT STATUS MAPS, DANGER ZONES CAUSED BY LANDSLIDES, AND OTHER TYPES OF MAPS APPLIED IN THIS CIRCULAR IS THE NATIONAL COORDINATE SYSTEM VN-2000 WITH THE LOCAL MERIDIAN, ZONE 3, AT THE SAME SCALE.

4. ENGINEERING STRUCTURES SUCH AS DRILLING MACHINES, DITCHES, INTERSECTIONS BETWEEN THE MAIN LINE AND CROSS-LINES, START AND END POINTS OF THE LINES SHALL BE MEASURED USING GEODETIC EQUIPMENT, STARTING FROM CONTROL POINTS WITH ACCURACY FROM THE MERIDIAN PARALLEL LINE UPWARDS, WITH AN MEAN POSITION ERROR OF 2.0M/1.0M FOR THE PLANE LOCATION/ELEVATION OF THE ENGINEERING STRUCTURE.

5. ESTABLISH A GEODETIC CONTROL NETWORK TO SERVE THE MEASUREMENT OF GEOLOGICAL ENGINEERING STRUCTURES, WITH BASE POINTS ARRANGED IN THE NETWORK FOLLOWING THE PRINCIPLE OF GRADUAL DECREASE FROM HIGHER TO LOWER LEVELS; SELECT THE MEASUREMENT METHOD USING GNSS STATIC TECHNOLOGY OR CHAIN ANGLE MEASUREMENT NETWORK BASED ON THE TOPOGRAPHIC CONDITIONS AND OBJECTS IN THE AREA; TECHNICAL REQUIREMENTS OF EACH LEVEL OF THE NETWORK SHALL COMPLY WITH THE CURRENT EFFECTIVE REGULATIONS ON THE ESTABLISHMENT OF GEODETIC CONTROL NETWORKS.

ART. 27. CURRENT STATUS SURVEY OF LANDSLIDES AT THE SCALE OF 1:2,000

IMPLEMENT IN ACCORDANCE WITH THE PROVISIONS OF ART. 15 OF THIS CIRCULAR, ADJUSTED TO THE SCALE OF 1:2,000.

ART. 28. DEEP ELECTRICAL RESISTIVITY TOMOGRAPHY ALONG THE LINE

1. OBJECTIVES AND TASKS:

a) DETERMINE THE THICKNESS OF WEATHERED LAYERS AND THEIR PHYSICAL PROPERTIES;

b) DETERMINE THE WEAKNESS ZONES OF ROCKS AND SOILS;

c) IDENTIFY AND DETERMINE FAULT ZONES, FRACTURED AND CRACKED ZONES.

2. LINE DESIGN

a) THE DESIGNED LINE MUST ENSURE THE COLLECTION OF ENOUGH LONGITUDINAL SECTION INFORMATION FROM THE TOP TO THE BOTTOM OF THE LANDSLIDE;

b) THE NUMBER OF LINES DEPENDS ON THE CHARACTERISTICS AND SCALE OF THE LANDSLIDE, WITH A MINIMUM OF TWO LONGITUDINAL LINES AND ONE TRANSVERSE LINE TO CONTROL THE WIDTH OF THE SLIDE BLOCK;

c) MEASUREMENT NETWORK AT 10M/POINT/LINE;

d) THE DEPTH OF THE SURVEY MUST CONTROL THE ENTIRE WEATHERED LAYER.

3. TECHNIQUES SHALL COMPLY WITH THE PROVISIONS OF CIRCULAR NO. 33/2014/TT-BTNMT OF JUNE 10, 2014 ISSUED BY THE MINISTER OF NATURAL RESOURCES AND ENVIRONMENT ON NATIONAL TECHNICAL REGULATIONS ON ELECTRICAL EXPLORATION METHODS.

ART. 29. DRILLING AND EXCAVATION WORK

1. EXCAVATION WORK SHALL BE CONDUCTED IN ACCORDANCE WITH THE PROVISIONS OF ART. 16 OF THIS CIRCULAR.

2. DRILLING WORK

a) OBJECTIVE: TO ACCURATELY DETERMINE THE THICKNESS OF WEATHERED LAYERS, WEAKNESS ZONES OF ROCKS AND SOILS, FAULT ZONES, FRACTURED AND CRACKED ZONES; TO SERVE THE FIELD GEOLOGICAL SAMPLING AND TESTING WORK; TO PROVIDE INFORMATION FOR ENGINEERING TECHNICAL SOLUTIONS;

b) LOCATION SELECTION: ON THE LANDSLIDE SITE, ON THE GEOPHYSICAL LINE, TO ENSURE MAXIMUM CONTROL OVER WEATHERED LAYERS;

c) DEPTH: SATISFY ONE OF THE FOLLOWING CONDITIONS (IN ORDER OF PRIORITY):

- CUT THROUGH THE GREATEST EXPECTED SLIDE ARC BY 10M;

- DRILL INTO THE BEDROCK LAYER BY AT LEAST 10M;

- PASS THROUGH THE LOCAL EROSION LEVEL BY 10M;

d) NUMBER: AT LEAST 3 HOLES PER LANDSLIDE SITE;

đ) IMPLEMENT IN ACCORDANCE WITH NATIONAL STANDARD TCVN 9437: 2012 - DRILLING FOR GEOLOGICAL EXPLORATION.

d) Number of boreholes: a minimum of 3 boreholes/1 slide point;

đ) Carry out in accordance with National Standard TCVN 9437:2012 - Geological Exploration Drilling.

Article 30. Field Testing Work

1. Standard Penetration Test (SPT)

a) Location: conducted at exploration boreholes;

b) Quantity: 1 test every 2 meters of depth from the top of the borehole, with a minimum of 3 tests for each weathering layer;

c) Standard Penetration Test (SPT): carried out according to National Standard TCVN 9351:2012: Construction Soil - On-site Testing Method - Standard Penetration Test (SPT).

2. In-situ Plate Load Test

a) Location: conducted at excavation pits and wells;

b) Quantity: 3-5 tests for each stratigraphic division to ensure representativeness and wide coverage;

c) Only carried out when undisturbed samples cannot be obtained;

d) Conducted according to National Standard TCVN 9354:2012: Construction Soil - On-site Determination of Modulus of Deformation Using Flat Plate Loading Test.

Article 31. Sampling, Processing, and Analysis

1. Collection, processing, and analysis of bulk samples shall be carried out according to Clause 1, Article 17 of this Circular.

2. Collection of Geotechnical Soil Samples

a) Location: undisturbed geotechnical soil samples are collected from trenches, excavation pits, wells, and boreholes within the area of landslides but in intact sections;

b) If the conditions specified in point a are not met, samples are taken from locations with similar geological objects, slopes, and degrees of weathering closest to the landslide sample collection points;

c) Number of samples: collect one sample per soil layer (weathering zone) in excavation pits; collect one sample every 2 meters from the top of the borehole, staggered relative to the Standard Penetration Test (SPT);

d) Collection of undisturbed geotechnical soil samples: collect soil samples to determine geotechnical properties according to National Standard TCVN 2683:2012 - Construction Soil - Sampling, Packaging, Transportation, and Preservation of Samples.

3. Collection of Geotechnical Rock Samples

a) Location: geotechnical rock samples are collected from rock faces that have collapsed or fallen rocks;

b) Number of samples: 1-2 representative samples for petrographic characteristics, degree of fracturing, and fracture zones;

c) Size: 20x20x20 cm;

d) Sample collection is carried out according to current regulations.

4. Sample Analysis

a) Soil sample analysis: analyze geotechnical properties of soil and rock (minimum: unit weight (∆; g/cm³));³); internal friction angle (φ, degrees); cohesion force (C, kg/cm²) in different states;

b) Rock sample analysis: analyze geotechnical properties of rock; analyze characteristic geotechnical properties of rock (minimum: unit volume weight (γ, g/cm³));³); internal friction angle (φ, degrees); cohesion force (C, kg/cm²);

c) Sample analysis is carried out according to current regulations.

5. Other Types of Samples

a) Depending on the actual causes of landslides, additional types of samples may be collected and analyzed as designed in the project description.

b) Processing and analysis of samples shall be carried out in accordance with current regulations.

Article 32. Establishment of Landslide Status Maps at Scale 1:2,000

1. Synthesize and process field survey data on current landslide status, flash floods, and other geological disasters; geological structure, tectonics, geomorphology, weathering crust; hydrogeological and engineering geological conditions; vegetation cover, civil infrastructure; results of sampling and analysis.

2. Prepare component diagrams

a) Petrographic component diagram at scale 1:2,000;

b) Weathering zone destruction diagram at scale 1:2,000;

c) Hydrogeological component diagram at scale 1:2,000;

d) Engineering geological cross-sections along profiles;

đ) Landslide status map at scale 1:2,000;

e) Infrastructure vulnerability diagram due to geological hazards at scale 1:2,000;

g) Diagrams showing other influencing factors affecting the landslide process.

3. Completing Data

Carried out according to Clause 4, Article 19 of this Circular.

Article 33. Establishing a stable slope model for land and rock at a scale of 1:2,000.

Implement in accordance with the provisions of Article 20 of this Circular.

Article 34. Creating a landslide hazard zoning map at a scale of 1:2,000.

Implement in accordance with the provisions of Article 22 of this Circular.

Chapter IV.

IMPLEMENTING PROVISIONS

Article 35. Effective Date

1. This Circular takes effect from February 15, 2026.

2. In cases where the referenced documents in this Circular are amended, supplemented, or replaced, they shall be implemented according to the new regulations.

Article 36. Implementation Organization

1. The Director of the Vietnam Geological and Mineral Resources Department shall be responsible for disseminating and supervising the implementation of this Circular.

2. Ministries, ministerial-level agencies, government-affiliated agencies, provincial People's Committees under central cities, and related organizations, institutions, and individuals shall be responsible for implementing this Circular.

3. During the implementation process, if there are difficulties or obstacles, relevant organizations, institutions, and individuals are requested to promptly report them to the Ministry of Agriculture and Rural Development for consideration and resolution./.