Worldwide, a large set of initiatives have been carried out aiming to understand the benefits offered by Nature-Based Solutions (NBS) in urban areas. The European Commission (EC) has founded different projects that have performed scientific literature reviews regarding this topic. To objectively compare their results and consolidate the consensus about the impacts and benefits of NBS, we performed a text mining analysis. This methodology coupled with a visual representation of the data allowed to convert the EC funding projects reports (corpus) into a meaningful structured analysis. This method demonstrated that despite the different literature review methodologies of each report, there are common trends exhibited by the results, e.g., the NBS installation as a strategy of urban resilience, the recognition of ecosystem services (ESS) delivered by nature in urban spaces, or the importance of the EC’s supporting role in the promotion of NBS. In addition, some network specific trends have also emerged and complemented the analysis: the assessment of the NBS performance with indicators, the participatory planning approach to NBS (involving citizen and local communities) and the economic value of their services.

Worldwide, research community has studied the benefits of green and blue spaces implementation in urban areas, generating a great amount of literature regarding this topic. Since these solutions are of interest to face climate change impacts in cities, the European Commission (EC) has funded several projects to make an extensive review of the available literature. Three of these projects were especially studied here, namely EKLIPSE, Mapping Assessment of Ecosystem and their Services- Urban Ecosystem (MAES: Urban Ecosystems), and NATure-based URban innoVATION (NATURVATION). They all aim to identify the physical and social impacts, benefits and trade-offs of Nature-Based Solutions (NbS).To objectively compare findings presented in the deliverable reports, a text-mining approach was carried out. This methodology coupled with a data visual representation allowed to convert the EC projects reports (corpus) into a meaningful structured analysis. As a result, a graphical representation was created, making possible to recognize concepts, patterns and attributes addressed by each text, as well as stakeholders and their position with respect to the topic. The text mining analysis was implemented through Gargantex Blue Jasmine Version (an open source software developed by ISC-PIF). Gargantex results permitted to recover a list of key-terms from each corpus based in their co-occurrence in the whole text. These terms were used to elaborate a visual representation or network, placing the words strongly related close to each other and characterizing the obtained clusters by a similar color.This approach underlined the specific focus of each project: the conciliation between urbanisation and urban ecosystems (MAES), or the economic valuation and monetisation of NbS (NATURVATION) for instance. Moreover, it demonstrated that despite the different literature review methodologies of each report/project, there are some common trends exhibited by the obtained graphical networks and their statistical attributes. For instance, the need to assess the NbS performance with some adapted indicators; and the important EC supporting role in the implementation of NbS. Similarly, some regulating (e.g. water quality or temperature reduction) and cultural (e.g. recreation or health benefits) services are more addressed.  This analysis can be applied to all kind of corpus, which makes it easy to understand different and similar concepts and approaches of a set of text data. A text-mining analysis can be conducted over the direct references of NbS benefits, on a collection of publications of a research database like Scopus or Science Direct. 

The need to adapt and increase the resilience of urban areas regarding the issues induced by urbanization and climate change effects (e.g. floods, Urban Heat Island, pandemics, etc.), has led to propose several strategies as the Natural-Based Solutions (NBS), which are focus on restoring natural processes such as infiltration and evapotranspiration (ET) in urban areas. In consequence, the increasing interest on NBS installation (highly supported by the H2020 program of the European Commission) by urban planners, decision-makers, researchers and the residing population has conducted to question the most efficient ways of NBS deployment. In this context, the urban dynamics (e.g. population density, land use patterns, transport network, etc.) and the distribution of green areas at different spatial scales play a key role that characterise the urban development in the territory.Based on the study of an urban agglomeration named Est-Ensemble, located at the east of Paris (France), this research aims to: i) determinate the fractal dimension of the built-up and green areas by using 2 different box-counting methods; ii) set the potential areas to install NBS, through the development of an iterative downscaling scheme over the built-up structure with the software Fractalopolis, and following a polycentric approach inspired on the urban form of Ile de France Region, and iii) assess the population access to the nearest green spaces and deficit of green spaces.Further, from local scale measurements of ET made close to Est-Ensemble agglomeration, the authors carried out a multifractal analysis of the ET data to better evaluate the observed scaling behaviour. This will be coupled with spatial approach developed above to evaluate the impact of temperature reduction of different land use scenarios. This research is partly supported by the French ANR EVNATURB project.

The growth of the world’s population living in urban areas has led to change from natural to highly dense and impermeable landscapes. Moreover, the intensity and frequency increase of extreme events resulting from climate change (e.g. inundations, heat waves) produce a degradation of urban systems resilience capacity. The integration of nature-based solutions NbS in urban spaces has been widely accepted, like a sustainable strategy that allows to tackle these urban challenges while building resilience and improving well-being and health. NbS are inspired by the nature, favouring natural processes in the cities like water infiltration or evapotranspiration (ET). Thanks to the latest, the vegetation shadow and wind dynamics favours air temperature reduction during heatwave events or mitigation of Urban Heat Island (UHI) phenomenon. Consequently, the distribution of urban green spaces might impact heat fluxes dynamics, by reducing temperature and its perception. They may also reduce virus spreads and also the sensitivity factors to them. Following a spatial approach, this study aims to analyse the green space distribution across different scales in the agglomeration located in the east of Paris (France) and various scenarios of its development. To achieve this goal, the spatial simulation model “Fractalopolis” is used. This allows to generate fractal urban forms using an iterative downscaling scheme (IFS: Iterative Function System) applied to existing large scale patterns of green areas. This work enables to analyse i) the access of population to the nearest green area and the fractal dimension of public urban green spaces; and ii) the impact of temperature reduction of different land-use scenarios by coupling a multifractal analysis of ET scaling behaviour measured at the local scale.

Green roofs are widely recognized as a Nature-Based Solution that regulates the air temperature within urban environments. Thanks to the shading effect and the evapotranspiration process (ET), the temperature decreases in the green roof surrounding area. Hence, the implementation of green roofs in urban environment for this purpose requires the quantification of ET-related processes at different scales. Nevertheless, because of complexity of the ET process, different methods of measurement have been used at different scales. However, no agreement about the way to assess ET rates over green roofs has been reached between the scientific community, as well as its behaviour at different urban scales is still unclear. Therefore, more investigations on ET measurements are required for better understand and analyse its spatial and temporal variability at different scales.For this purpose, a Larger Aperture Scintillometer (LAS) MKI from Kipp&Zonen was installed over a wavy-green roof of 1 ha, the Blue Green Wave (BGW), located in the Ecole des Points ParisTech (France). The main objective of this set-up was to assess the refractive index-structure parameter (Cn2) fluctuations from which ET can be deduced by means of the Monin-Obukhov similarity theory and the surface energy balance. As LAS is mainly influenced by fluctuations of air temperature, a radiometer equipped with a temperature sensor was installed in addition over the BGW. Then, the scaling statistics of Cn2 and temperature were studied through their power spectral density and their structure function.The results obtained from the power spectral density demonstrated the scaling invariance of Cn2 and temperature over certain ranges of scales. The spectral exponents are close to 5/3 for Cn2 and to 2 for the temperature. Regarding the scaling exponents of the structure functions, the multifractal feature of the structure parameter Cn2 and the temperature was confirmed. The scale-invariant properties of the empirical data were characterised using the Universal Multifractal framework.