[DREAL OCCITANIA] Urban Spot 2015 (DREAL Oc Methodology)

The creation of an urban spot gives an image of the urban hold at some point. Land files allow the reconstruction of an urban spot from the built parcels according to the date of construction of the premises. In this way, the progress of urbanisation within a territory can be traced over time. In particular, it is possible to measure: — the surface of urban spots per commune on different dates. — the rate of change in these areas per municipality. a — Surfaces considered: Urban sprawl mapping is done from the unbuilt property table of the 2016 land files, which contains the artificialised areas of the plot. (the 2016 land files provide construction information until 2015). B — Scope of observation: The method retains all built plots. C — Observation period: The reference date for urbanisation is calculated from the year of construction of the oldest premises. Plots with a space that do not specify the date of construction are retained and therefore form part of the built parcels with the urban reference spot. For the entire Occitania region, the calculation of the urbanised area was carried out in 2005 and 2015, D — Method of urban task development: From the locators of the built plots, disks corresponding to the artificialised surface were constructed using a GIS tool (Qgis, MapInfo). A maximum radius of 70 meters is applied so as not to retain very large plots that can increase the result. For clearly underestimated parcels, a minimum radius R = 20 metres is applied. The minimum artificialisation of a plot is 1 256 m². A 30-metre expansion is carried out. After union, an erosion of 30 meters is carried out. This expansion/erosion makes it possible to define areas of urban influence, taking into account in particular the roads within the stains. e — Results of the method: The urban spots obtained are divided according to the municipal boundaries to obtain a summary table at the communal grid allowing aggregations at all planning scales.