The complexity of the built environment plays an essential role on the local urban microclimate. Therefore, this work aims to assess the impact of buildings arrangement on the overall turbulent flow dynamics. This study is conducted for the neighborhood of an open auditorium located in an urban area. A set of experiments were accomplished using a wind tunnel, together with a set of Computational Fluid Dynamics (CFD) simulations. Both the experiments and the CFD simulations were carried out for a set of meteorological conditions identified as prevailing in the auditorium area. The physical and numerical approaches were used to assess the wind patterns for the reference scenario. Furthermore, a series of mitigation measures was simulated to evaluate their effectiveness in reducing the wind speed at pedestrian level in the neighborhood. The overall results emphasize the role of the mitigation measures to reduce wind speed and potentially improve pedestrian wind comfort levels in the auditorium. The originality of this paper relies on the design and test of the set of proposed mitigation measures, through the combination of complementary tools, as well as the expertise of distinct practitioners, and their insights regarding their effectiveness.

The potential effects of future climate in green freshwater resources are an issue that needs to be addressed. The main goal of this study is to evaluate how future climate will affect green water scarcity resources, by calculating green water scarcity characterisation factors (CFs) under a reference (period 1986 to 2005) and amedium-term future (period 2046 to 2065) climate, based on the principles established by Quinteiro et al. (2018). This study considers a higher spatial resolution (9 x 9 km) than Quinteiro et al. (2018), improving the knowledge of green water scarcity conditions in mainland Portugal. The CFs were calculated considering two different interfaces: (1) interface green freshwater - topsoil (ws), and; (2) interface green freshwater - atmosphere (wa). At the interface ws, the relation between the changes on green freshwater flows and the surface blue freshwater recharge is considered, while at the interface wa the relation between the evapotranspiration (ET) recycled to the atmosphere and the precipitation levels at the same water-shed level are considered. The green freshwater scarcity CFs were developed based on ET values, which in turn were calculated based on meteorological variables obtained with the Weather Research and Forecasting (WRF) model. Some regions of Portugal are currently suffering of pressure on green freshwater resources (mainly in Central littoral and Western coastal areas). In general, green freshwater scarcity CFs is projected to increase in Portugal under future climate in comparison to the CFs obtained for reference conditions. Green freshwater scarcity CFs at the interface ws increase from 101 to 150%, while CFs at the interface wa increase from 301 to 800%. These results show that strategies and policies to support the management of green freshwater resources and land use planning, ensuring the highest level of freshwater productivity of crops and forests, should be developed. (C) 2019 Elsevier B.V. All rights reserved.

Green infrastructures play an essential role in urban planning, namely with their potential to reduce the impact from air pollution episodes together with extreme weather events.This chapter focuses on the assessment of green infrastructures' benefits on current and future microclimate and air quality patterns in Porto's urban area (Portugal).The effects of green infrastructures on flow dynamics are evaluated for the baseline scenarios by means of numerical and physical simulations, using the computational fluid dynamics (CFD) model VADIS and the wind tunnel of the University of Aveiro.The baseline morphological (BM) scenario focuses on the current morphological characteristics of Porto's urban area, while a baseline green (BG) scenario comprises the replacement of built-up areas by green areas and parks.In addition, the benefits of green infrastructures on air quality are assessed for the baseline and under future climate scenarios.The air quality simulations focus on particulate matter, one of the most critical air pollutants with severe impacts on human health.For the BM scenario, the simulated concentrations are compared with hourly averaged PM10 concentrations measured during a weekday at the air quality station located within the study domain.

Air pollution is an environmental and social issue at different spatial scales, especially in a climate change context, with an expected decrease of air quality. Despite the technological evolution of the last decades in the transport sector, road traffic emissions are still one major source of air pollution at the city level. The main goal of this study was to evaluate the influence of a set of resilience measures, based on nature-based solutions, in the wind flow and in the dispersion of air pollutants, in a built-up area in Portugal. For that, two pollutants were analysed (NOX and PM10) and four scenarios were developed: i) a baseline scenario, ii) an urban green scenario, iii) a green roof scenario, and iv) a “grey” scenario (without trees). Two models were used, namely the Weather Research and Forecasting model (WRF) and the CFD model VADIS (pollutant dispersion in the atmosphere under variable wind conditions). The WRF model was used to initialize the CFD model, while the last was one used to perform the set of numerical simulations, on hourly basis. The implementation of a green urban area promoted a reduction of air pollutants concentrations, of about 16% [PM10] and 19% [NOx] in the overall domain; while the application of green roofs showed an increase of concentrations (reaching 60% during specific time periods). Overall the results showed that a strategic placement of vegetation in cities has the potential to make an important contribution to the improvement of air quality and sustainability of urban environments.

Urban mobility accounts for 38 and 19% of nitrogen oxide (NOx) and particulate matter (PM) emissions at European urban areas, respectively. Despite of all the technological development around automobile industry, urban areas are still facing problems related to exposure to high levels of air pollutants. Increasing the accuracy of both emissions and air quality modelling from road traffic is a key-issue for the management of air pollution in road transport sector. This study assessed the influence of using different road traffic emission models on the accuracy of air quality modelling with street-level resolution, having as a case study an urban area located on the centre region of Portugal. Two emission models, with different complexity levels regarding the ability to characterise the traffic dynamics were analysed, namely, transport emission model for line sources (TREM) and vehicle-specific power (VSP), based on data obtained in an experimental campaign. To perform the air quality simulations, the pollutant dispersion in the atmosphere under variable wind conditions (VADIS) model was used and two pollutants were analysed: NOx and PM10. The results showed that the magnitude of PM10 and NOx concentrations were result of a conjoint influence of traffic dynamics and meteorological conditions. Comparison between measured and modelled data showed that the VADIS model could track the evolution of NOx levels, for both emission models considered, displaying a high correlation (> 0.8) between traffic-related NOx emissions and NOx concentrations. For PM10, VADIS model is more sensitive to the differences in the emissions calculation; however, it was observed that the traffic-related PM10 emissions accounts 1.3–8.4% to the PM10 concentration levels at the study area.