CN104462721A - Sub-compartment forest fire spreading simulation method base on multiple plane directions - Google Patents

Abstract

The invention discloses a method for simulating the spread of forest fires in a small group of forests based on multiple directions on a plane. The invention is to calculate the spreading speed of the forest fire spread direction from the fire point to multiple directions around the fire point, and realize the fire area simulation of the forest fire fire area based on the raster image data, and accurately simulate the spread of the forest fire.

Description

A Simulation Method of Forest Fire Spread in Small Class Based on Plane and Multiple Directions

1. Technical field

The invention relates to a method for simulating the spread of forest fires at the scale of forest subcompartments for guiding forest fire fighting, in particular to a method for simulating the spread of forest fires at the scale of forest subcompartments based on multiple directions on a plane.

2. Technical background

The most widely used forest fire spread models in my country include Rothermel model and Wang Zhengfei forest fire spread model. Wang Zhengfei’s forest fire spread model is only applicable to terrains with a slope below 60°, and the uphill and the wind is going uphill. Later, Mao Xianmin and others considered the combination of wind direction and terrain and derived uphill, downhill, left flat slope, The equations of the five directions of the right flat slope and the wind direction can be calculated to obtain the forest fire spread speed in these five directions.

Therefore, in the practical application of the forest fire spread model extended by Wang Zhengfei and Mao Xianmin et al., because only the parameters of the wind speed in the above five directions are considered, the practical application is limited. The invention calculates the forest fire spreading speed in multiple directions from the scale of the forest sub-compartment, and is used for simulating the forest fire spreading, and can obtain higher-precision simulation results.

3. Contents of the invention

In order to improve the accuracy of forest fire spread simulation in small forest sub-compartments, the object of the present invention is to provide a method for simulating forest fire spread in small sub-compartments based on plane multiple directions.

The object of the present invention is achieved like this: the included angle φ ' of arbitrary direction wind on the slope surface satisfies tanφ '=tanφ*cosΔ, wherein, φ is slope angle, and Δ is slope direction and wind direction deflection angle, Δ=θ- A, θ is the wind direction angle, and A is the slope angle. Forest fire spread speed R in any direction of the forest small class, Among them, R is the spreading speed, R ₀ is the initial speed of spreading, K _s is the coefficient of combustibles, φ is the terrain slope angle, V is the wind speed, is the included angle of wind in any direction on the slope, is the angle between the clockwise direction and the upward direction. The angles of the special directions are as follows: uphill φ′=φ, downhill φ′=180°-φ, left flat slope φ′=0, right flat slope φ′=0.

Compared with the prior art, the present invention has the following advantages:

Simulating forest fires from multiple directions avoids the imperfection of forest fires simulated by only velocities in five directions in the past. It has strong dynamics, less dependent parameters, and easy acquisition, which improves the accuracy and efficiency of simulation. Accurately locate the position in each direction after the fire spread, and the model is simple and easy to implement; according to the proposed multi-directional digital model on the plane, the process of small-scale forest fire spread can be directly simulated.

4. Description of drawings

Figure 1 is a schematic diagram of multiple directions of forest fire spread from the ignition source.

Figure 2 is a schematic diagram of multiple directions on the plane of forest fire spread in small forest squads.

5. Specific implementation methods:

The method for simulating forest fire spread in a small class based on multiple directions on the plane is different from the existing technology, and has been greatly improved, specifically:

First of all, as shown in Figure 1, the fire spread direction of the forest sub-compartment takes the fire point as the center and multiple directions around the forest sub-compartment as the direction of forest fire spread.

Secondly, the fire spread direction of the forest sub-compartment is centered on the fire point to multiple directions as the forest fire spread direction of the forest sub-compartment. Angle φ′ of the wind in any direction on the slope, φ′=arctan(tanφ*cosΔ), where φ is the slope angle, Δ is the angle of slope and wind direction, Δ=θ-A, θ is the wind direction angle, A is the slope angle.

Finally, the forest fire spread speed R in any direction of the forest small class, Among them, R is the spreading speed, R ₀ is the initial speed of spreading, K _s is the coefficient of combustibles, φ is the terrain slope angle, V is the wind speed, is the included angle of wind in any direction on the slope, is the angle between the clockwise direction and the upward direction. The angles of the special directions are as follows: uphill φ′=φ, downhill φ′=180°-φ, left flat slope φ′=0, right flat slope φ′=0.

Claims (3)

1. A method for simulating the spread of forest fires in small forest fires based on multiple directions on the plane, characterized in that: in the small forest fires, the basis for considering the initial velocity of forest fires spreading, the coefficient of combustibles, terrain slope, wind speed, and the direction angle of forest fires spreading A method for simulating forest fire spread in arbitrary winds. 2. the method for forest fire spread simulation in any direction of forest sub-class according to claim 1 is characterized in that the angle φ ' of arbitrary direction wind on the slope surface, satisfies tan φ '=tan φ * cos Δ wherein, φ is the slope angle, Δ is the angle of slope and wind direction, Δ=θ-A, θ is the angle of wind direction, and A is the angle of slope. 3. forest fire spreading speed R in any direction of the forest sub-class according to claim 1, Among them, R is the spreading speed, R ₀ is the initial speed of spreading, K _s is the coefficient of combustibles, φ is the terrain slope angle, V is the wind speed, is the included angle of wind in any direction on the slope, is the angle between the clockwise direction and the upward direction. The angles of the special directions are as follows: uphill φ′=φ, downhill φ′=180°-φ, left flat slope φ′=0, right flat slope φ′=0.