An urban environment is the region surrounding a city. Most inhabitants of urban areas have nonagricultural jobs. Urban areas are very developed, meaning there is a density of human structures such as houses, commercial buildings, roads, bridges, and railways.
Natural urban environment
The natural urban environment incorporates not only parks and gardens but also air, soil and water, and a diversity of habitats, including neglected areas like brownfield sites and land along transport corridors. The natural environment in urban areas often experiences faster and more extreme rates of change than in rural areas. For instance, river flows may be faster and more prone to extreme variations.
The diverse habitats in urban areas create a variety of ecosystems providing important ecological services for biodiversity, climate, water and flood management. They are also important for individual health and wellbeing and for local communities, providing opportunities for exercise, leisure, education and employment, as well as creating a sense of place.
Urban areas face an evolving set of environmental pressures including climate change. At the same time, the existing infrastructure of pipes, drains, sewers and flood defences is ageing and needs replacing. This provides an opportunity to increase the use of flexible green infrastructure in new developments and regeneration projects in order to enhance flood control measures and reduce the potential for pollution.
A more strategic approach is needed to increase the amount of green infrastructure, making the most of existing natural features and creating new ones, and tightening up legislation and planning policy to protect particular parts of the urban ecosystem such as the green belt, gardens and trees.
The built urban environment
The built environment describes the artificial, man-made structures in which we live, work and play. All artificial surfaces, including buildings, roads, pavements etc. come under the heading of the built environment.
The built environment has evolved over time since the earliest man-made structures. Today we live in a very crowded, urbanised world in which the volume of artificial surfaces is increasing rapidly.
Urban heat island
As urban areas develop, changes occur in their landscape. Buildings, roads, and other infrastructure replace open land and vegetation. Surfaces that were once permeable and moist become impermeable and dry. These changes cause urban regions to become warmer than their rural surroundings, forming an “island” of higher temperatures in the landscape.
Heat islands occur on the surface and in the atmosphere. On a hot, sunny summer day, the sun can heat dry, exposed urban surfaces, such as roofs and pavement, to temperatures 50–90°F (27–50°C) hotter than the air1, while shaded or moist surfaces—often in more rural surroundings—remain close to air temperatures. Surface urban heat islands are typically present day and night, but tend to be strongest during the day when the sun is shining.
Surface and atmospheric temperatures vary over different land use areas. Surface temperatures vary more than air temperatures during the day, but they both are fairly similar at night. The dip and spike in surface temperatures over the pond show how water maintains a fairly constant temperature day and night, due to its high heat capacity.
Urban environmental management (UFM)
Historically, interaction between the various actors involved in UEM processes has been very weak and ineffective. While laws to effect such involvement existed, it was not exercised both on the part of local governments (adequate information was not provided), as well as other actors and citizens themselves (there was no commitment to participate). Information that was shared by the government was, in many cases, partial or selective. This put the entire decision-making process in the hands of the government as the main actor.
There has, however, been a growing awareness of environmental problems and its causes and effects. With a gradual increase in the transperancy and openness in the functional organization and operation of governments, legislation on information disclosure has been receiving considerable importance. Parallel to this has been a movement among the citizens to not only be aware of the processes of UEM within their community, but to also be involved in the design of decision making process itself. This calls for a major change in the basic understanding of citizens’ participation and the consequent needs of information for decision making processes from the points of view of all actors involved. With their direct involvement, the citizens of a community can be seen as major actors and partners in the process of planning. Such a give-and-take of information and decision support not only links the planning sector and the community, but also all sectors of the local government that affects the development of a region. Community involvement becomes all the more critical when the shortcomings and weaknesses of the local government to effectively deal with the range of problems are taken into account.
At the lowest level, community involvement can be seen as passive acceptance, where the community reorganizes and adjusts to the implemented public plans. Public sector plans then become a base on which private decisions are made. At higher levels of participation, however, the community is directly involved in the decision-making process at all levels. Thus matching and synchronizing public plans to private/individual plans become important, where public services are developed so that the private/individual plans can function and be implemented efficiently. It also calls for open and free participation at all stage of the process and with no restrictions or barriers.
Thus, interaction between the different actors at different levels of the planning processes and cycles becomes critical to respond to the increasingly complex policy and investment choices that urban communities face.