• Restricted areas: built-up areas, lakes, rivers, mountains and other zones considered in regional planning
instruments (like zones of rivers overflow).
• Protected areas: national and regional parks areas.
• Land use capacity: it is assessed using the standard international land use capacity classification into 9 classes
(land use capacity system elaborated since 1961 by the Soil Conservation Service of the Department of
Agriculture of the United States and adopted by the FAO in 1974). The better productive potential of the soil,
referring to first, second and third classes was excluded. This function can be therefore written as