What are the technical requirements for belts of sand-fixing and windbreak coastal forests under Vietnam Standard TCVN 12510-1:2018?
What are the technical requirements for belts of sand-fixing and windbreak coastal forests under Vietnam Standard TCVN 12510-1:2018?
Technical requirements of the belts of sand-fixing and windbreak coastal forests are specified in Section 3 of Vietnam Standard TCVN 12510-1:2018 as follows:
Criterion | Requirements |
The direction of belts of sand-fixing and windbreak coastal forests | |
- Main forest belt | The direction of the main forest belt is arranged to be planted perpendicular or nearly perpendicular to the main direction of the wind. |
- Sub-forest belt | The direction of the sub-forest belt is arranged perpendicular to the main forest belts, forming closed cells, in the form of checkerboard tiles. (Applies to areas with multiple wind directions) |
The width of belts of sand-fixing and windbreak coastal forests | |
- Main forest belt (m) | Minimum width 50 |
- Sub-forest belt (m) | Minimum width 5 |
The distance between the forest belts. | |
- Main forest belt (m) | 100 - 120 |
- Sub-forest belt | Depending on the terrain conditions to design |
Structural storey of the forest belt | - Windshield coefficient is from 0.3 - 0.5; - The holes are evenly distributed on the vertical cross-section of the forest belt. |
Cross-section of the forest belt | The forest belt has many rows of plants, the rows of plants in the belt are of equal or nearly equal height. |
Forest belt density (D) (m3) | A minimum of 150 |
What are the methods for determining the criteria of sand-fixing and windbreak coastal forests specified in Vietnam Standard TCVN 12510-1:2018?
Section 4 of Vietnam Standard TCVN 12510-1:2018, the methods for determining the criteria of sand-fixing and windbreak coastal forests are specified as follows:
Criterion | Methods | Test samples |
Forest belt direction | Determine the direction of the main wind according to local meteorological data; use a compass to determine the direction of the forest belt in the field. | At 03 locations on the length of the forest belt. Specifically: 01 point is in the middle of the forest belt, and the remaining 02 points are located 3m from outside the two ends of the forest belt. |
Forest belt width (m) | Directly measure; use a tape measure engraved with accuracy to cm/GPS locator, and measure the distance between the two outermost rows of plants of the forest belt. | At 03 locations on the length of the forest belt. Specifically: the 01 point is in the middle of the forest belt, and the remaining 02 points are located 3m from outside the two ends of the forest belt. The width of the forest belt is calculated as the average value of the 3 locations on the forest belt mentioned above. |
Distance between forest belts (m) | Directly measure; use a tape measure engraved with an accuracy line to cm, measure from the outermost plant row of one forest belt to the outermost plant row of the next forest belt. | At 03 locations on the length of the forest belt. Specifically: 01 point is located in the middle of the forest belt, and the remaining 02 points are located 3m from outside the two ends of the forest belt. The width of the forest belt is calculated as the average value of the 3 locations on the forest belt mentioned above. |
Structural storey of the forest belt | Conduct field depictions and draw forest belt diagrams | Calculate the wind jar coefficient specified in Appendix A of Vietnam Standard TCVN 12510-1:2018 on a forest strip with dimensions of 20m x 10m. |
Cross-section of the forest belt | Conduct field depictions and draw forest belt diagrams | On the forest strip measuring 20m x 10m. |
Forest belt density (E, m3) | Determine the necessary norms through standardized typical-pattern grid cells with an area of 200m2 (20m x 10m), the length of the cell parallel to the forest belt. (Details in Appendix A of Vietnam Standard TCVN 12510-1:2018). | The standardized typical-pattern grid cell quantity shall correspond to the length of the belts of sand-fixing and windbreak coastal forests as follows: - Length of forest belt ≤ 500 m: 02 OTC. - Length of forest belt from > 500 to ≤ 1,000m: 03 OTC. - Forest belt length > 1,000 m: 04 OTC. Methods for measuring and calculating forest belt density are specified in Appendix A of Vietnam Standard TCVN 12510-1:2018 |
What are the regulations on the determination of the density of the belts of sand-fixing and windbreak coastal forests under Vietnam Standard TCVN 12510-1:2018?
Under Appendix A of Vietnam Standard TCVN 12510-1:2018 on Plantation forest - Coastal protection forest, Part 1: Sand-fixing and windbreak coastal forests, the determination of the density of the belts of sand-fixing and windbreak coastal forests is prescribed as follows:
(1) Contents of the investigation
The contents of the investigation to determine the density (E, m3) of the belts of sand-fixing and windbreak coastal forests include forest belt height, forest belt width or depth, longitudinal tightness, and horizontal tightness of the forest belt.
(2) Method of making standardized typical-pattern grid cells
- The method of making standardized typical-pattern grid cells is a systematic stochastic method.
- Belt length ≤ 500 m: make 02 standardized typical-pattern grid cells; Belt length from > 500 to ≤ 1,000 m: make 03 standardized typical-pattern grid cells; Belt length > 1,000 m: make 04 standardized typical-pattern grid cells.
- Standardized typical-pattern grid cell shape and size: the standardized typical-pattern grid cell has a rectangular shape with an area of 200m2 with dimensions of 20m x 10m), the length of the cell is parallel to the forest belt.
(3) Measurement and counting in standardized typical-pattern grid cells
- Investigation of tall plant floors (Refer to Appendix B of Vietnam Standard TCVN 12510-1:2018):
Measure the chest diameter (D1.3) with a tape measure or glass caliper, a line engraving ruler with an accuracy of up to cm.
Measure the canopy diameter (Dt) with a tape measure in 2 directions East-West and South-North, the type of line engraving ruler with an accuracy of up to cm. Canopy diameter is the average value of 2 measurement directions.
Measure the height of the apex (Hvn) with a tall ruler, a type of line engraving with an accuracy of up to dm.
Measure height under branches (Hdc) with a height ruler, a type of ruler that engraves lines with an accuracy of up to dm.
- Drawing of forest belt diagrams (Refer to Appendix C Vietnam Standard TCVN 12510-1:2018)
By drawing spatial geometry, transfer the plants in the drawing strip measuring 20m x 10m from the field to the drawing on olive paper in the correct scale of 1/100 or 1/200.
(4) Internal calculation
- Determination of windshield coefficient
Determination of the windshield coefficient by the formula:
K = V'/V
Where:
V': average wind speed at different altitudes behind the forest belt
V: average wind speed at the corresponding elevations in front of the forest belt
- Determination of forest belt density
Determination of forest belt density by the formula:
E = Hđ x Rđ x Kd x Kn x Sđ
Where:
A: Forest belt density (m3);
Hđ: Forest belt height (m);
Rd: The width or depth of the forest belt (m);
Kd: Longitudinal tightness (The ratio of the total area of the canopy in the vertical section/ area of the forest belt in the longitudinal section);
Kn: Horizontal tightness (The ratio of the total area of the canopy section in cross-section/ area of the forest belt in cross-section);
Sđ: Is 1m in length of forest belt (m)
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