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| Author(s): |
Paula Shinzato
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Faculdade de Arquitetura e Urbanismo (FAU/SBI) |
| Defense date: | 2014-05-29 |
| Examining board members: |
Denise Helena Silva Duarte;
Lucila Chebel Labaki;
Leonardo Marques Monteiro;
Humberto Ribeiro da Rocha;
Demóstenes Ferreira da Silva Filho
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| Advisor: | Denise Helena Silva Duarte |
| Abstract | |
The objective of this work is to quantify the impact of vegetation on urban microclimates, under the canopy, due to soil-vegetation-atmosphere interactions. It considers the following effects: 1) the canopy itself, expressed by the variable leaf area index - LAI and the geometric openness distribution in the canopy (gap fraction); 2) the soil coverage, expressed by soil composition, soil temperature and soil humidity, and 3) the local microclimatic variables (air temperature, humidity, solar radiation, mean radiant temperature, surface temperature, wind direction and wind speed). Considering the impact of vegetation on urban microclimates as a function of soil-vegetation-atmosphere, and based on the outcomes of preview studies, this work starts from the hypothesis that for São Paulo climate and as a result of evapotranspiration and shadowing process, the reduction of air temperature under the canopy will be between 1°C to 2°C and for surface temperature, it will be around 20°C, both in relation to an area without tree shadowing. These effects are restricted to the borders of the park, especially under the conditions of low wind speed, approximately 1m/s. The methods are: 1) inductive, based on field measurements in summer and winter at Tenente Siqueira Campos Park (Trianon Park), in the city of São Paulo, registering microclimatic data and collecting information for canopy and soil; and 2) deductive, with the calibration of measured and simulated data by ENVI-met 3.1 Beta 5 and the simulation for different scenarios varying the canopy characteristics. To estimate the average leaf density for trees canopy two no-destructive indirect methods were applied: measurement of LAI using the equipment LAI-2000 (LI-COR) and the analysis of hemispheric photographs, using a software application Can-Eye. According to the simulation results, for different characteristics for canopy, it could be verified a maximum reduction of 1ºC in air temperature and 19°C for surface temperature, when comparing the obtained value under a dense canopy (elliptical form and LAI of 5m2/m2) to the conditions on the street. The maximum extension of these effects were up to 5m from the limits of the park, considering 1m/s for wind speed and 40% for soil humidity in the upper layer (0-20cm). The thermal index TEP calculated and it could be seen that the reduction of 1°C for air temperature can represent from 3°C to 5°C in terms of thermal comfort of people. By these results, the initial hypothesis has proven to be correct and showed not only the importance of the type of vegetation selected (canopy form, LAI values and geometric distribution of canopy openness) but also the characteristics of the surrounding environment (microclimatic and soil conditions). Furthermore, it will contribute to formulate public politics aiming to mitigate urban warming effect, mainly during daytime, in tropical cities. (AU) | |