Soil Sealing from Remote Sensing and GIS in the Urban Development Program (PAU) of Southeast of Madrid (Spain)
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Abstract
The aim of this paper is to integrate different sources of spatial information (cadastres, orthophotographies and satellite images), which also require different treatments, in order to be able to measure and evaluate the sealing of soils in a recent urban development project in the southeast of the city of Madrid, in order to establish a methodology of space-time monitoring of this parameter. Another objective is to show if the current urbanization process respects the European environmental guidelines in which waterproofed or sealed soil, inherent in economic development, coexists with natural spaces that allow to maintain some ecological functions such as softening the urban microclimate, setting growth levels of CO2 in stable figures in line with European environmental quality and standards, damping floods and preserving biodiversity.
The sealing values of soils measured from different sources and using complementary techniques generate similar results when the waterproofing is higher than 60%. However, the calculations obtained from satellite images vary according to their spatial resolution and the type of treatment applied. With the Spot satellite the sealing values are close to 24%, while with the Sentinel-2 the percentage rises to 30%. Orthophotographies offer greater spatial precision, so sealing levels (<20%, 20-40%, 40-60% and > 60%) have been established, but their low temporal resolution prevents continuous monitoring, at least annually. Therefore, it is necessary to use different cartographic sources when carry out a study of urban areas, since the different temporal, spatial and spectral resolutions allow to visualize different characteristics in each of them. Consequently, their complementarity helps to correct the possible inadequacies of each of them.