Mapping and Assessing Soil Sealing in Padua Municipality through Biotope Area Factor Index

Abstract

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.

Mapping Pervious Surfaces and Canopy Cover Using High-Resolution Airborne Imagery and Digital Elevation Models to Support Urban Planning

“…In urban landscapes, high spatial resolution is crucial to provide accurate urban cover classifications [29,32]. Urban cover assessment using high resolution imagery, in addition to offering a highly detailed map, allows the use of maps to drive urban transformations and to compare future scenarios [33]. Recently, the increasing accessibility of technologies led to a growing number of high spatial resolution (<3 m) experiments in urban contexts [7,29,32].…”

The Use of Cool Pavements for the Regeneration of Industrial Districts

“…This is also confirmed by the mapping of the Biotope Area Factor Index, which expresses the share of ecologically effective area to total land area [57]. Nearly the entire industrial district is characterized by values equal to zero (i.e., totally impervious area) [53]. The study focused on a representative sector (Figure 1b), with the aim to evaluate the microclimatic impacts and potential benefits of the redevelopment of ground surfaces.…”

“…In cities, the major amplifier of climate risk factors is the expected intensification of extreme climate phenomena, especially heat waves and intense rainfalls. In this context, the Veneto region is among the areas in Italy most affected by soil sealing, with a share of more than 12% sealed surface [53] This results in several environmental issues, including the presence of urban heat island, and problems in stormwater management. A number of studies have confirmed the presence of UHI in Padua, especially during the summer seasons [51,[54][55][56].…”

How to map soil sealing, land take and impervious surfaces? A systematic review

“…Hereafter, we refer to vegetation indexes as Band Ratio class, by including NDVI, NDBI, MNDISI, SAVI, and others indexes (García and Pérez 2016, Sun et al 2017, Gong et al 2019, Zhong et al 2019). The reclassification process is referred to papers that used ancillary data, for example Land Cover data, to derive soil sealing coverage (Jennings et al 2004, Pristeri et al 2020. The image interpretation category includes scientific articles that adopted human visual analysis to identify and to map impervious areas (Hartcher andChowdhury 2017, Lozano et al 2019).…”