Evaluating the Quality of Urban Green Spaces at Residential Urban Morphologies in The Federal District, Brazil

Quality of life is highly related to natural environments, including general health, mental health, physical health, social health, and longevity (WARD THOMPSON, 2011).

The studied area is situated in the Federal District, Brazil’s capital located in middle-west region, with nearly 3 million inhabitants (Figure 1).

In this region, the climate is tropical with two very defined seasons, being arid from May to September with low precipitation rates and high evaporation rates, and a rainy between October and April, with storms with high rainfall intensity. The average annual precipitation varies at the range of 1,200 to 1,700 mm in a territory of about 6,000 sqkm. The urban morphologies studied are the RH1 – Single family houses with high occupancy rate (allotments with 250 sqm of area) and RH5 – Single family houses with low occupancy rate (allotments with 2000 sqm of area). The RH1 is characteristic of low-income suburbs and the RH5 is normally founded in medium to high income suburbs. The selected Urban morphologies studied are illustrated in (Figure 2). The quantity and quality of the urban green spaces was evaluated in two steps, as can be seen in (Figure 3). First, it was analyzed the number of trees per inhabitant in the two USTs, using the urban vegetation data provided by SEDUH [1] and socioeconomic data provided by Castro [2].

The second step was to assess the volume of vegetation per square meter in these USTs, using the UVST methodology purposed by [3] The method of UVST consists in use LAS (LiDAR) data, that is processed in ArcGIS, being able to visualize the vegetation height, volume, and difference between surfaces, that are divided in ground, high, medium, and low vegetation. With the volume value, it was used the correction factor in 0,33, through the shape of the tree crown. The last step to create the UVST was to divide the volume per vegetation cover area [4-6].

The main results showed that RH5 have a higher volume of vegetation in its green spaces are three times greater than RH1. The volume of vegetation per square meter obtained for RH1 was 0.20 m³/m², while for RH5 was 0.65 m³/m² (Figure 4), showing that RH5 has more vegetation volume than RH1. The number of trees per inhabitant also show the difference between the two USTs. The RH1 has only 0.05 trees per inhabitant, and RH5 has 3.42trees per inhabitant. That shows that RH1, with a high population density, has a lower amount of vegetation, in quantity and quality, than RH5. The RH1, as described above, is a UST characteristic of low-income neighborhoods [7,8].

The two test examples were used to compare two similar areas, both being residential areas. Even in these examples, it was possible to see differences in volume’s vegetation. In (Figure 2) is noticeable that RH1 has less tress and more constructions than RH5, showing that RH5 has a potential of a higher quality life, even if it has the lowest population density [9,10]. The methodology might be applied in different areas of Federal District, to indicate if there is inequality between different USTs related to green spaces. Improving the quantity and quality of urban green spaces is a social justice question. There is a lack in planning and policies in cities to improve these spaces. Their socioeconomic benefits can also be enhanced when the implementation of green spaces is associated with other collective use equipment, such as community centers, health centers, and schools.

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