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Soil sealing at present is one of the most important environmental issue, especially in urban and suburban areas. Asphalt, new building and infrastructures frequently degrades the correct ecological and hydraulic function of soil system. Direct and indirect impacts of soil sealing affects important ecosystem services: carbon sequestration, micro-climate regulation, hydrogeology risk mitigation and purification of air and water. This research focuses on the evolution of soil sealing in Padua by spatial modelling of an ecological urban index, the Biotope Area Factor Index (BAF), to estimate the permeability at urban scale. Calculation of soil sealing is based on Volunteered Geography Information (VGI) approach with 26 non-professional operators, and land use mapping and classification from high resolution orto-photos (20 cm/pixel) at 4 multispectral bands (VIS and NIR). The workflow is a sequence of geo-processing in QGIS for the calculation of the BAF values by tessellation grid analysis on 1000 m2 areal units and by the averaged value of the study area. The study area is 300 ha (Forcellini), located in the E sector of the city of Padova (Italy). By the VGI analysis 8,498 features were therefore extracted, classified, and ranked. Hence, due to geometric inconsistencies related to the different operators, an accurated topological analysis was performed. Globally, 1,000 topological errors were identified and then reduced to 7,913. Therefore, it has been made a merge from 26 shapefile, to generate a unique file of the area. The land use categories were clustered and correlated with corresponding BAF index values and intersected with exagon tessellation. By the plug-in GroupStat of QGIS, it has been created a table normalizing the BAF values to 1000m2 area of the hexagon polygon. The attribute table was therefore joined to the exagon shapefile, and then normalised to the average value of all features inside the polygon. The modelling of BAF index show that asphalt areas (BAF = 0) cover the 44 % of the all neighborhood, green areas ( BAF = 1) cover 55%, while the other classes the 1% . The combination of a Volunteered Geography methodology with the use of an opensource GIS showed the potentiality of remote sensing to assess soil sealing and to model ecological urban index at urban scale.
Topic Area: [1.5] Public participation and active dissemination of information – citizen science and VGI Abstract Type: Oral Presentation
Academic: Yes Data Provider: No Data User: No INSPIRE Implementer (IT): No INSPIRE newbies: No Policy Officers: No Public Administration (MS/Regional/Local): No Thematic specialists: No
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