Urban areas are characterised by substitution of natural covers with artificial covers, which are most of the time impervious.
Impervious artificial covers affect a large number of environment processes, such as the water cycle, the carbon cycle, energy balance, biodiversity, etc. For example, bitumen surfaces block water infiltration and thus prohibit natural groundwater recharge. As a consequence, artificial covers strongly impact the environment quality.
Artificial surface can be mapped through satellite sensors and ground survey.