Prof David Simon

Cities are dynamic human artifacts undergoing changes which influence their relationships with the surroundings. Initially the rural-urban interface was conceived as characterised by distinctly different land-use patterns and human behaviours. However, growing urban population and increasing rural-urban interdependencies have not only changed this perception, but have also brought attention to ensuing environmental problems.

Cities constantly undergo changes influencing their relationships with their outskirts. These outskirts, neither urban nor rural, are variously known as rural-urban (rurban), peri-urban or transitional areas and the process peri-urbanisation.
Earlier, this interface was primarily conceived in terms of neatly identifiable dichotomous rural-urban divide. Implicit in this construct was the idea that urban and rural areas were characterised by very different land-use patterns and human behaviours and that the boundaries between these spaces and places were easily discernible and clear cut. Given the differential rates of growth of urban populations across the globe and growing rural-urban interdependencies, this perception has changed and the attention has now shifted to treating the peri-urban areas as dynamic mixes of functions and land uses - residential and recreational; population densities; sources of urban food, construction materials, as urban waste disposal or treatment sites etc.

This change has occurred following the major deindustrialisation of the 1970s and early 1980s which has witnessed two spatially opposite effects. While the middle class and higher income groups lived in fashionable inner districts or older suburbs, the integrated transport and information and communications technology (ICT) revolutions enabled electronics industries to locate in the outskirts. Since the ICT professionals could rely on computerised communications to work from home, they lived in rural or semi-urban localities which were also well equipped with high amenities.

As their role within the world economy changed during the 1990s, Southeast and East Asia underwent a new form of metropolitan urbanism, reflecting some of the same transport and technological changes, rapid industrialisation and dramatic increases in standards of living. Dubbed extended metropolitan regions (EMRs), these areas were characterised by rapid urban growth and polycentricity as well as the spread of urban activities and land uses into rural areas. Earlier seen as incompatible, rural and urban activities juxtaposed to create complex mosaics. This gave rise to concepts such as 'kotadesatie' (city-villagisation), quickly superseded by what is termed as 'desakota' (city-village).

Elsewhere in Southeast Asia, in South Asia, sub-Saharan Africa, Latin America, and the Caribbean, rapid and spatially polarised urbanisation under neoliberal conditions has created often wide and persistent, if dynamic, transition zones that combine various rural and urban conditions. Moreover, their importance for the cities that they surround in absorbing urban migrants, as sources of food and other resources and as key areas for the disposal of urban wastes was increasingly appreciated. They are also typically zones of mixed land use and livelihoods. On account of these characteristics, and the interactions between such areas and the cities, these transition zones came to be known as peri-urban zones or interfaces (PUIs). In other European or Europeanised languages, the PUI concept is expressed somewhat differently.

Even as the peri-urbanisation assumes different forms in different localities, the process is not new. It is just that it is gaining significance from the viewpoint of environmental implications and management which have generally been severe and are increasingly recognised as unsustainable. The problems relate to river, soil, and groundwater contamination from toxic waste posing health hazards, severe agricultural contamination, chronic air pollution not just in large cities, but also in peri-urban and rural areas usually marked by outdated technologies and lack of controls. Ironically, increase in ground water availability through reduced evapotranspiration and increased runoff in urban areas can be harvested only in relatively unpolluted or pure water conditions.

In case of China, industrialisation at any cost during the last few years has resulted in loss of prime agricultural land to urban activities in the major river deltas, a loss that cannot readily and sustainably be compensated for by bringing lower-potential land elsewhere into production or by intensifying existing production. The realisation has led to pollution abatement measures and greenhouse gas emission reductions as well as China's change of attitude to the climate change debate and acceptance of the implications of the Intergovernmental Panel of Climate Change's Fourth Assessment Report in 2007. Consequently, there has been recognition that a few dam projects have been environmentally disastrous. These attitudinal changes, if carried through and implemented broadly, also have international and political implications in terms of negotiations on climate change and a successor to the Kyoto Protocol.

Environment related changes, however, remain a low priority in other rapidly urbanising and industrialising poorer countries. The processes of peri-urbanisation and the nature of PUIs here are diverse. The following section elucidates the various categories of development-environment issues that have received attention. Issues of poverty and the struggle to survive and find adequate livelihood activities amid rapid change loom large. PUIs reflect, as defined earlier, highly dynamic interfaces between urban and rural relations involving forces and pressures that are national and even international in terms of human mobility, commodity and financial flows and their valuation and claims on environmental resources. These interlinkages have necessitated an ecosystem dynamics approach to solving issues related to peri-urban environmental change.

Land conversion One of the most intractable environmental issues everywhere is the inevitable conversion of agricultural and forested land to urban uses, particularly catering to affluent sections of the society. This reflects the vulnerability of larger tracts of relatively undeveloped and cheaper land for potential abuse-combined with the ability to site disturbance causing or polluting facilities away from wealthier and/or dense urban populations. In other words, negative environmental externalities may be imposed on the PUIs.

Peri-urban agriculture and environment
Usually agricultural activities, whether in urban or peri-urban areas, are assessed together because of their common role in feeding cities. Conceptually also, it is difficult to distinguish between the two. And yet peri-urban cultivation becomes more difficult and precarious as loss of cultivable land to a combination of sale and land degradation reduces local food self-reliance and the ability to sell any surpluses to urban dwellers. On the other hand, however, greater proximity and accessibility to the enlarged urban market can create new opportunities to intensify peri-urban agriculture and to specialise in higher value horticultural crops that require greater husbandry - and hence financial outlay and perhaps risk.

Waste disposal and contamination
The widespread location of polluting infrastructure in the PUI imposes negative externalities on local residents. These comprise disturbance from large numbers of dump trucks, sewage tankers, and livestock transporters; smell and potentially disease carrying vectors; and, contamination of soil and groundwater by leachate. The associated inequity and distributional issues are underscored by the general absence or gross inadequacy of sanitary facilities and other services for peri-urban residents, mostly reliant on pit latrines -the inappropriate silting of which also often contributes to groundwater contamination.

End note
This review explores environmental issues and problems at the PUIs or urban fringe in diverse contexts in order to illustrate some of the differences and similarities between groups of countries defined in terms of historical political economies. However, these groupings are not internally coherent or homogeneous. On the contrary, their diversity is profound and the connections across groups are increasing. Despite this, the evidence shows that many processes, concerns, and problems are similar, notwithstanding withholding varying severity and likely impacts due to the differing resource bases, median living standards and institutional capacities. With the coming up of new technologies in the future, such categorisations may change.

Crucially, fringe or PUI areas should be treated as integral elements of urban systems in both functional and planning terms because they and their environments are integral to the growth and operation of growing cities; their integration into urban planning systems would facilitate holistic and systems oriented planning. This is likely to be achieved, however, only when the challenges of urban management and planning constraints on resources, capacity, and political priority, as well as a multiplicity of administrative boundaries are overcome.