Multi-stage ventilation corridor construction method considering path density and space connectivity

Abstract

The invention discloses a multi-stage ventilation corridor construction method considering path density and space connectivity. The method comprises the following steps: obtaining a potential ventilation corridor; calculating an included angle between the potential corridor and the prevailing wind direction; extracting a corridor center line with relatively high linear density; gradually screening according to the linear density from high value to low value to form a primary gallery; deducting potential galleries in the buffer area of the first-stage galleries to obtain potential second-stage galleries; calculating the included angle between the remaining potential secondary galleries and the prevailing wind direction, and removing the potential secondary galleries with the included angle larger than 45 degrees; removing a potential secondary corridor with a relatively short length; calculating the length of the potential secondary corridor passing through the green space and the water area; calculating the length of the potential secondary gallery passing through the surface temperature high-value area; and the potential galleries with relatively long lengths are selected as secondary galleries. By the adoption of the technical scheme, the actual construction cost of the ventilation corridor is reduced, corridor deficiency in a local area is supplemented, and peripheral air inflow and internal air exchange and circulation are effectively promoted.

Description

Technical Field

[0001] The present invention belongs to the technical field of ventilation corridors, and in particular to a method for constructing a multi-level ventilation corridor taking into account path density and spatial connectivity. Background Art

[0002] In recent years, with the rapid development of social economy, a large number of people have poured into cities. More and more people are living in cities, which has brought about a rapid increase in the demand for living and production land, and the scale of urban construction land has continued to expand. However, under the pressure of food security, ecological environmental protection, and resource and environmental carrying capacity, the constraints on the scale of construction land have become increasingly tight. Most cities have chosen high-rise, high-density, compact and intensive building layouts during construction. As the main living and production site, the compact environment of the city can improve the efficiency of land use and the accessibility of service facilities, and inject vitality into the development of economy, society and culture. However, the rapid expansion of construction land will lead to an increase in the roughness of the underlying surface and a change in the land cover type, which will bring problems to the urban climate environment. Surrounded by high-rise buildings, the city's ventilation capacity has declined, the overall wind speed has gradually decreased, and the number of calm days has increased, making urban problems such as high temperature heat waves, heat island effects, haze, and air pollution more severe, reducing the comfort and livability of residents' living environment. Scientific ventilation corridor construction can improve urban ventilation capacity, promote the flow of fresh air from the outside into the interior, effectively alleviate problems such as urban heat islands and pollution, and promote sustainable urban development. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a multi-level ventilation corridor construction method that takes into account path density and spatial connectivity, reduce the actual construction cost of the ventilation corridor, supplement the lack of corridors in local areas, and effectively promote the inflow of external air and the exchange and circulation of internal air, so as to better play the functional effect of the ventilation corridor.

[0004] To achieve the above object, the present invention adopts the following technical solution:

[0005] A method for constructing a multi-level ventilation corridor taking into account path density and spatial connectivity comprises the following steps:

[0006] Step 1), obtain potential ventilation corridors;

[0007] Step 2), quantify the direction of each potential corridor and calculate its angle with the prevailing wind direction;

[0008] Step 3), calculate the line density of potential corridors and extract the center lines of corridors with higher line density;

[0009] Step 4), gradually screen according to line density from high value to low value, remove the center line with an angle greater than 45° with the prevailing wind direction, and form a first-level corridor;

[0010] Step 5), deduct the potential corridors in the buffer zone of the primary corridor to obtain the potential secondary corridors;

[0011] Step 6), calculate the linear direction average of the remaining potential secondary corridors, calculate the angle between the linear direction average and the prevailing wind direction, and eliminate the potential secondary corridors with an angle greater than 45°;

[0012] Step 7), remove potential secondary corridors with shorter lengths;

[0013] Step 8), calculate the length of potential secondary corridors crossing green spaces and water areas;

[0014] Step 9), calculate the length of the potential secondary corridor passing through the area with high surface temperature;

[0015] Step 10), select the potential corridor with longer length in steps 8) and 9) as the secondary corridor.

[0016] Preferably, in step 1), the prevailing wind direction is determined according to the characteristics of the urban background wind environment, the source point and the sink point are set, and the potential ventilation corridor is extracted using the minimum cost path analysis.

[0017] Preferably, in step 2), the linear directional average is used to quantify the direction of each potential corridor and calculate its angle with the prevailing wind direction.

[0018] Preferably, in step 2), LDM is used to represent the linear directional average value of the potential corridor. Among them, θ i Refers to the direction of a set of polyline features; A NE A represents the angle of the northeast wind into the corridor, NE =|LDM-45°|; A E represents the angle of the easterly potential corridor, A E =|LDM-90°|.

[0019] Preferably, in step 4), the high-density value path is used as the main line, connected through the low-density value path, and the central path of the next level of line density data is superimposed in sequence to gradually complete the connectivity of the first-level corridor, and the central line with an angle greater than 45° with the prevailing wind direction is eliminated.

[0020] Preferably, in step 5), a first-level corridor buffer is established, potential corridors within the buffer range are removed, and duplicate potential corridors are deleted, and the remaining potential corridors are used as alternative potential second-level corridors.

[0021] The present invention addresses the problem of insufficient exploration of constructing multi-level corridors by quantitatively evaluating and screening the results of minimum cost path extraction. The study considers the construction goals of corridors of different levels, ensures that the direction of the corridor conforms to the prevailing wind direction, and that the first-level corridor runs through the study area and optimizes the high-density area. The second-level corridor connects and extends the ventilation network and connects the high-temperature and low-potential action space and the water green space compensation space. Based on the identified potential corridors, after quantitative evaluation and screening, the construction of multi-level ventilation corridors at the urban scale is realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0023] Figure 1 It is a flow chart of the multi-level ventilation corridor construction method considering the path density and spatial connectivity;

[0024] Figure 2 It is a flow chart of potential ventilation corridor identification;

[0025] Figure 3 This is a schematic diagram of the construction results of the northeast wind ventilation corridor;

[0026] Figure 4 This is a schematic diagram of the construction results of the easterly ventilation corridor. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. Embodiment 1:

[0030] The embodiment of the present invention provides a method for constructing a multi-level ventilation corridor taking into account path density and spatial connectivity. Figure 1 As shown, perform the following steps:

[0031] Step 1) Determine the prevailing wind direction according to the characteristics of the urban background wind environment, set the source and sink points, and extract potential ventilation corridors using minimum cost path analysis;

[0032] The embodiment of the present invention uses Changzhou's administrative division, land survey, construction, and traffic network data; raster data: Landsat8 remote sensing images, digital elevation models, and high-resolution models; other data: China's basic ground meteorological observation data, China's ground climate data daily value data set, Changzhou Statistical Yearbook, etc., all of which have been pre-processed.

[0033] In ArcGIS, Model Builder was used to establish a batch processing model for potential ventilation corridor extraction. The source points arranged at the northeastern and eastern boundaries of the study area (i.e., the main urban area of ​​Changzhou City) and the corresponding sink points arranged at the southwest and west were input into the model to calculate the minimum cost path from multiple points to multiple points. Finally, all raster results were converted into polylines and merged to obtain the potential ventilation corridors in the study area. The processing flow is as follows: Figure 2 As shown, 621 potential corridors are formed by northeasterly winds downward, and 551 potential corridors are formed by easterly winds downward.

[0034] Step 2), use the linear directional average to quantify the direction of each potential corridor and calculate its angle with the prevailing wind direction;

[0035] The angle between the calculated potential corridor and the northeast wind direction and the east wind direction is calculated as follows:

[0036]

[0037] A NE =|LDM-45°|

[0038] A E =|LDM-90°|

[0039] Where LDM represents the linear directional mean of the potential corridor, θ i Refers to the direction of a set of polyline features, A NE A represents the angle of the northeast wind into the corridor, E It indicates the angle of the corridor where the easterly wind is potential.

[0040] Step 3), calculate the line density of potential corridors and extract the center lines of corridors with higher line density;

[0041] When constructing the first-level corridor, the line density of the minimum cost path is mainly considered, and the search radius is set to 200 meters and calculated. The results show that the line density values ​​under northeast wind and east wind range from 2.68 to 684.04 km / km respectively. 2 3.3-841km / km 2, the spatial distribution is obviously different. The high density values ​​of the potential corridors under the northeast wind are staggered and concentrated in the middle and southern parts of the study area, such as the banks of the Xinzaogang River and the South Canal, the Beitang River, the Hengtang River and the surrounding areas of the Ecological Park, and the Shanghai-Wuhan Expressway. The high values ​​of the potential corridors under the east wind are more concentrated and larger, and are distributed approximately in parallel in the middle of the study area. The density values ​​between the two and the east and west sides of the study area are relatively low, and the high values ​​are distributed in Guanhe, along the Beijing-Hangzhou Canal, the Beijing-Shanghai Line, Wunan Road and Wunan River. Extract the center line of the corridor with higher line density.

[0042] Step 4), gradually screen according to line density from high value to low value, remove the center line with an angle greater than 45° with the prevailing wind direction, and form a first-level corridor;

[0043] First, the central paths of the 1st and 2nd level ranges with high density values ​​are retained. Since the paths formed by high values ​​are not completely connected, and as the density value screening range expands, the number of paths also increases significantly, the embodiment of the present invention takes the high-density value path as the core, and the low-density value path is mainly used for connection. The central paths of the next level of line density data are superimposed in sequence to gradually complete the connectivity of the first-level corridors. The center lines with angle values ​​greater than 45° are not considered, and finally 13 first-level ventilation corridors that run through the study area under northeast wind and east wind are screened layer by layer.

[0044] Step 5) Establish a first-level corridor buffer zone, remove potential corridors within the buffer zone, delete duplicate potential corridors, and use the remaining potential corridors as candidate potential second-level corridors;

[0045] Step 6), calculate the linear direction average of the remaining potential secondary corridors, calculate the angle between the linear direction average and the prevailing wind direction, and eliminate the potential secondary corridors with an angle greater than 45°;

[0046] Step 7), remove potential secondary corridors with shorter lengths;

[0047] Finally, 85 and 69 paths were retained under the northeast wind and east wind, respectively. These potential corridors are the basis for the construction of secondary corridors in the study area, and can better extend and supplement the functions of the primary corridors.

[0048] Step 8), calculate the length of potential secondary corridors crossing green spaces and water areas;

[0049] Step 9), calculate the length of the potential secondary corridor passing through the area with high surface temperature;

[0050] Step 10), select the potential corridor with longer length in steps 8) and 9) as the secondary corridor.

[0051] In order to enable the secondary corridor to better improve the wind environment of the high temperature or low potential action space in the city, the action space and compensation space distribution of the study area are combined for quantification and screening. The action space selects the high and higher values ​​of the surface temperature inversion results as the high temperature area, the low value of the ventilation potential evaluation result as the low potential area, and the compensation space selects the water area and green space distribution. The length of the potential corridor passing through the action space is used to represent its influence range. The longer the length, the wider the influence range of the potential corridor on the urban built-up area; the length of the green space and water area crossed by the potential corridor is calculated to represent the influence of the low temperature compensation space on it. The larger the value, the more green space and water area are distributed within the path range, and the fresh air can be better promoted in the built-up area by relying on these compensation spaces. The intersection obtains the crossing length of the potential corridor and the length of the green space and water area passed through. The scope of action of different potential corridors on the high temperature area and low potential area is very different, and some do not pass through the high temperature area of ​​the city. In order to better improve the urban wind and heat environment, the length of crossing the two action spaces is classified into five categories, and the results of high value and high value are selected respectively. Finally, 7 secondary corridors under northeast wind and 10 secondary corridors under east wind are obtained. Together with the first-level corridor, a multi-level ventilation corridor under two prevailing wind directions in the study area was constructed, such as Figure 3 and Figure 4 .

[0052] The embodiments described above are only descriptions of the preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for constructing a multi-level ventilation corridor taking into account path density and spatial connectivity, characterized in that: The following steps are involved: Step 1), obtain potential ventilation corridors; Step 2), quantify the direction of each potential corridor and calculate its angle with the prevailing wind direction; Step 3), calculate the line density of potential corridors and extract the center lines of corridors with higher line density; Step 4), gradually screen according to line density from high value to low value, remove the center line with an angle greater than 45° with the prevailing wind direction, and form a first-level corridor; Step 5), deduct the potential corridors in the buffer zone of the primary corridor to obtain the potential secondary corridors; Step 6), calculate the linear direction average of the remaining potential secondary corridors, calculate the angle between the linear direction average and the prevailing wind direction, and eliminate the potential secondary corridors with an angle greater than 45°; Step 7), remove potential secondary corridors with shorter lengths; Step 8), calculate the length of potential secondary corridors crossing green spaces and water areas; Step 9), calculate the length of the potential secondary corridor passing through the area with high surface temperature; Step 10), select the potential corridor with longer length in steps 8) and 9) as the secondary corridor.

2. The method for constructing a multi-level ventilation corridor taking into account path density and spatial connectivity as claimed in claim 1, characterized in that: In step 1), the prevailing wind direction is determined according to the characteristics of the urban background wind environment, the source and sink points are set, and the potential ventilation corridors are extracted using the minimum cost path analysis.

3. The method for constructing a multi-level ventilation corridor taking into account path density and spatial connectivity as claimed in claim 2, characterized in that: In step 2), the linear directional average is used to quantify the direction of each potential corridor and calculate its angle with the prevailing wind direction.

4. The method for constructing a multi-level ventilation corridor taking into account path density and spatial connectivity as claimed in claim 3, wherein in step 2), LDM is used to represent the linear directional average value of the potential corridor, in, θ i Refers to the direction of a set of polyline features; A NE A represents the angle of the northeast wind into the corridor, NE =|LDM-45°|; A E represents the angle of the easterly potential corridor, A E =|LDM-90°|.

5. The method for constructing a multi-level ventilation corridor taking into account path density and spatial connectivity as claimed in claim 4, characterized in that: In step 4), the high-density value path is taken as the main line, connected through the low-density value path, and the central path of the next level of line density data is superimposed in sequence to gradually complete the connectivity of the first-level corridor, and the central line with an angle greater than 45° to the prevailing wind direction is eliminated.

6. The method for constructing a multi-level ventilation corridor taking into account path density and spatial connectivity as claimed in claim 5, characterized in that: In step 5), a first-level corridor buffer is established, potential corridors within the buffer range are removed, and duplicate potential corridors are deleted, and the remaining potential corridors are used as alternative potential second-level corridors.

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