Although cities as we know them occupy the same location for centuries, the physical infrastructure which comprise the built environment are not static but altered continuously by dynamic forces of change initiated by various public and private interests. This modification of the urban environment occurs at a variety of scales ranging from the residential relocation decisions taken on different levels including public road-building programmes and private house projects .
In addition, to differing degrees in different countries, the operation of these forces is influenced by national , regional and local planning. The net effect of these processes is seen most clearly in the land-use structure of the city. Urban Geographers examine the principal models and theories of urban land use.
For analytical convenience these are arranged into four broad types based on the principles of:
1. morphogenesis;
2. human ecology;
3. political economy;
4. postmodernism.
Link(s) and Sources(s):
Migration and its Impact on City
Rashid's Blog: An Educational Portal 