The rising environmental issues on contemporary cities urgently calls for sustainable planning policies. Implementation of nature-based solutions, ecosystem services, and green infrastructures associated to green spaces management is at present of paramount importance. In contrast to policies mainly focused on public greenery, the inclusion of private green in planning strategies might be a promising pathway. The general aim is mapping and classifying urban green spaces in Padua, a city of 93.3 km² (Northeast Italy). Specific aims are (i) testing an NDVI-derived extraction from very high-resolution orthophotos; (ii) classifying property status; (iii) highlighting multilevel relationships and strategies for urban green spaces implementation and management; (iv) assessing greenery in relation to per capita population. By performing remote sensing and GIS analyses, a first detailed global map of urban green spaces in Padua was created; then, binary classification and thematic maps for rural/non-rural, public/private, municipal/non-municipal greenery were produced for all urban units. Results show that, among total green spaces (52.23 km²), more than half are rural. Moreover, private green spaces represent 80%, while within public areas (20%) less than 10% are municipal (5 km²). We therefore highlight scenarios for planning policies in Padua by providing tools to policymakers for an integrated management of green spaces, where private greenery might also contribute to ecosystem services implementation for common urban well-being.

The mitigation of urban heat islands (UHIs) is crucial for promoting the sustainable development of urban areas. Geographic information systems (GISs) together with satellite-derived data are powerful tools for investigating the spatiotemporal distribution of UHIs. Depending on the availability of data and the geographic scale of the analysis, different methodologies can be adopted. Here, we show a complete open source GIS-based methodology based on satellite-driven data for investigating and mapping the impact of the UHI on the heat-related elderly risk (HERI) in the Functional Urban Area of Padua. Thermal anomalies in the territory were mapped by modelling satellite data from Sentinel-3. After a socio-demographic analysis, the HERI was mapped according to five levels of risk. The highest vulnerability levels were localised within the urban area and in three municipalities near Padua, which represent about 20% of the entire territory investigated. In these municipalities, a percentage of elderly people over 20%, a thermal anomaly over 2.4 °C, and a HERI over 0.65 were found. Based on these outputs, it is possible to define nature-based solutions for reducing the UHI phenomenon and promote a sustainable development of cities. Stakeholders can use the results of these investigations to define climate and environmental policies.

Soil degradation is one of the main environmental issues within the international agendas on sustainability and climate adaptation. Among degradation processes, soil sealing represents the major threat, as ecosystem services dramatically decrease or are even nullified. The increasing use of big open data from satellites combined with AI algorithms are making geodata mining and mapping techniques essential to quantify soil sealing. Different keywords are adopted to define the phenomenon. However, at present, review articles presenting the state-of-the-art on mapping soil sealing by including the most common definitions are currently not available. Hence, we analyzed: (a) impervious surface, (b) soil sealing, (c) land take, (d) soil consumption, (e) land consumption. We provide a systematic review of remote sensing platforms and methodologies to map and to classify soil sealing, by highlighting: (a) definitions; (b) relationships among study areas, scales, platforms, resolutions, and classification methodologies; (c) emerging trends and policy implications. We performed a systematic search on Scopus (from 2000 to 2020), identifying 1277 papers; 392 focused on mapping soil sealing. ‘Impervious surface’ is the dominant definition. The phenomenon is more studied by the USA, China and Italy and, ‘soil sealing’ is recently more adopted in EU. Most studies focuses on mapping soil sealing at urban scale. We found Landsat are the most adopted platforms; they are frequently used for multi-temporal analyses. Eleven methodologies were identified: automatic classifications are the most adopted, dominated by pixel/sub-pixel-based approaches; other methods include Band Ratios, Supervised, OBIA, ANN. The majority of mapping analyses are performed on 30 m resolution in areas of 1000–10 000 km². Landsat images are less used for smaller areas. In conclusion, as study area size increases, a decrease in image resolution with the use of more completely automatic classification methodologies is recorded. However, most studies focuses on comparing classification techniques rather than supporting policy making for sustainable urban planning. Thus, we encourage to fill the gap by developing approaches that applicable to international policies.

Over the last few years, soil sealing has been recognized as one of the major threats in terms of soil degradation and loss of ecosystem services. Although many efforts have been promoted to increase the awareness of safeguarding soil for stakeholders, its value as a non-renewable resource as well as soil-related services in urban ecosystems is not implemented enough in urban planning and policies. Due to the spatially explicit component and the geographical scale of soil sealing, mapping and quantifying the number of sealed surfaces is crucial. The aim of this paper was to estimate and geovisualize the soil sealed in the city of Padua (Italy) at a very detailed scale, testing the use of the Biotope Area Factor (BAF) index. Moreover, the paper aimed to simulate an alternative mitigation scenario in a specific study area of the city. Spatial analysis was performed testing the BAF index in a Geographic Information Sistem (GIS) environment and using aerial ortho-photos at very high resolution. The results show different values of the BAF index for all four neighborhoods from 0.35 to 0.69. In the mitigation scenario, the value of the BAF index was improved using a measure of green roofs. In conclusion, the paper provides an insightful case study for enriching the debate about soil sealing and gives scientific support for sustainable urban planning.

Soil sealing is a worldwide phenomenon of covering of natural or seminatural soil with impervious surfaces, such as built-up or paved surfaces. It is widely recognized as a major environmental issue which drives landscape fragmentation and ecosystem services degradation and loss. Italy is one of European countries with the highest extent of soil sealing. The most affected area is northern Italy, especially the Po Valley with more than 12% of sealed surfaces. According to official data, Veneto Region and the city of Padua are seriously affected by this phenomenon. The Biotope Area Factor is a consolidated ecological urban index for mapping soil sealing, adopted in different European cities to support urban planning; it expresses the ratio of the ecologically effective surface area in relation to the total land area according to land cover classes. The general aim of this study is to map and to assess soil sealing in the whole municipal territory of Padua using the Biotope Area Factor (BAF) index. We tested and adopted a digital land cover map together with aerial images to perform a BAF analysis on the whole municipal territory of Padua. By using sample areas previously analyzed, we validated our source data by a double spatial validation process; therefore, soil sealing analysis was scaled-up to the municipality territory. Results show that in the city of Padua, the average BAF index value is 0.6; totally permeable surfaces (BAF = 1) cover 59.5%, whereas totally “sealed” surfaces (BAF = 0) are 40.3% of the municipal territory (93 km²). Most of the sealed soil is located in the east sector and in the historical core of the city, with BAF values ranging from 0 to 0.2. A particularly critical area is identified within the new industrial area of the city, which is strongly affected by soil sealing. BAF maps are useful tools to identify critical areas by geovisualizing surface permeability at a very detailed scale and by enabling further analyses for hydrogeological risk assessment and urban climate regulation. Moreover, the use of BAF maps at urban scale today represent an important tool for urban management, especially for policy makers who are planning mitigation and compensation measures to control soil sealing.

Nature-based solutions (NBSs) are considered essential measures to face climate change in cities. Riparian ecosystems are often undervalued as NBSs even if they represent an “already plugged-in” ecosystem service provider. However, applied research on urban riparian ecosystems is scarce. To fill the gap, this study frames the role of these ecosystems as a frontline mitigation and adaptation strategy by (i) investigating how urban riparian ecosystems experienced a process of urbanization from World War II until today in Padua (Italy), (ii) estimating how effective was carbon sequestration, and (iii) assessing how an afforestation process might contribute to mitigation scenarios. Land use/land cover changes are first mapped with high-resolution aerial images and, by using InVEST models, carbon sequestration is estimated. Results highlight that impervious surfaces notably increased along these ecosystems; hence, carbon sequestration was negative (−928 Mg/C). The future scenario (2022–2050) indicates an increase of carbon stocks (+4,329.95 Mg/C), giving a contribution toward city carbon neutrality. Results suggest that, in the recent past, the urban management and policies did not provide clear and well-defined planning of these areas. On the contrary, at present, urban riparian ecosystems might represent already existing multi-functional NBSs to be restored and enhanced within cities for climate-resilient planning and for increasing the life quality of city dwellers. Finally, our methodology provides a replicable spatial database for supporting urban planning policies.