Environmental Engineering Reference
Fig. 4.6 Valle del Tronto, Italy. Urban sprawl in the valley
of consistent settlement diffusion in coastal areas that tend to join together
various coastal centers, thus occupying the free areas. The original multicen-
tric model tends to transform itself into a metropolitan model . To this phe-
nomenon is added settlement diffusion toward rural hill areas in the near
inlands, or hill centers rolling down into the valleys. In the case studies for the
Marche and Tuscany regions, this tendency is very evident (Fig. 4.7).
The impression is that there is a growing attractiveness of some rural areas
[13, 14] that become progressively occupied by new pseudorural settlements,
tending, on the one hand, to increase the hemorrhage from historical, estab-
lished, inhabited centers pouring out in a state of abandonment ; on the
other hand, they tend to contribute to the formation of new intercommunity
settlement systems, essentially implied cities.
In the literature, the imagination knows no bounds when introducing differ-
ent definitions to describe the progressive changing of the city: from the “city-
region” of Giancarlo De Carlo , to the “reticular structure” of Giuseppe
Dematteis , or the “branching city” ; from “diffuse city” [19, 20] to
“disperse city” , “infinite city” , or “dissolved city”  (Figs. 4.8-4.13).
Finally, Pierre Donadieu's concept of “urban countryside”  describes a
rural territory that can no longer be distinguished from the city. The common
denominator in these different meanings is the accentuation of settlement dis-
persion that is manifest across the planet, with the appearance of great urban-
ized areas where the population is growing at the rate of 50million per year.