Problematic definitions of fixed and fluid urban boundaries

In many urban researches the boundaries of the city or the neighborhood that is to be studied is the first problematic theme. The researchers usually take the administrative boundaries to start the study. In page 27 of "Handbook of urban studies" edited by Ronan Paddison, there is a useful explanation: 

Housed in rural area out of Busan, Korea, photo by yewenyi

" For the most part, researchers lend to accept administrative boundaries due to the difficulty in obtaining adequate data for defining urban areas. It is therefore necessary to consider whether definitions of urban areas are fixed of fluid. Where they are fixed, changes in urban population must occur by demographic process only: births, deaths and migration. Where they are fluid, reclassification becomes an important element in urban population change. Fluid definitions make comparisons over time difficult, but tend to better characterize the changes that identify urban settlements patterns. Where boundaries are more fixed, urban growth may not be fully reflected in statistics. Where they are fluid, population may be shown to increase despite declines to the core. Here it is necessary to recognize whether the boundaries of an urban area are underbounded or overbounded. In the former case, there are additional contiguous areas built up around an administratively defined core that could be considered part of the urban centre given alternate definitions. In the latter case, the urban centre includes low-density areas that more resemble rural areas in character. Adjustments to the urban boundary are made more frequently where fluid definitions are used. Adjustment problems occur when definitional parameters change. In fact, the flexibility in defining the city will determine, to some extent, the degree of over- of underboundedness of a centre and the speed of change. Underbounded cities tend to arise in places to these boundaries tend to occur rather quickly."

There is another description about the administrative urban boundaries in a book chapter titled " Forecasting Urban Features: A Systems Analytical Perspective on the Development of Sustainable Urban Regions" written by Gordon Mitchell in "Exploring Sustainable Development: Geographical Perspectives", edited by Martin Purvis and Alan Grainger. We read in page 106: " ... the urban metabolism concept focuses renewed attention on the inadequacies of traditional markers used to trace urban limits. Established administrative boundaries vary widely in origin and may bear little relations to the current size, functions or influence of the city. Equally, attempts to define the city in terms of its built-up area ignore the much wider sphere of urban influence that is a vital component of any exploration of urban metabolisms. Such definitions of urban boundaries are of themselves problematic in that they often rest on essentially arbitrary and geographically inconsistent distinctions between different densities of population and development. Attributing urban functions to particular settlements can also be controversial. In the contemporary world, there are extensive built-up areas- including, for example, the self-proclaimed 'cities' that crowd the Los Angeles Bay area- that are almost exclusively residential, lacking most of the productive and market functions that have traditionally been regarded as urban hallmarks." 

More posts about urban planning books:

Book Review: Testimonies of the City. Identity, Community and Change in a Contemporary Urban World

Urban Planning Book: Sprawl: A Compact History

Denver has increased 10 to 15 percent in public transit use in the downtown