S. Mohammad Barar

A Systematic Approach based on GIS Application for Urban Analysis and Planning

This approach is based on a study of the distribution of significant urban land use activities categorised upon their locating potency. Sets of land use categories with their respective ranges of functionality become the indicators of urban spatial organisation. With the shortage of appropriated urban information, common in most third world countries, this approach leads to an understanding of the logic of urban organisation and provides a base for urban development planning. An important urban project for eastern part of Tehran (2,000,000 inhabitants 1338 hectares) has successfully applied this approach.

The Problem:

The accelerated growth of Iranian contemporary urban society makes great demands on the evolving field of urban land use planning. Study of this development in Iran has emerged and evolved in the past three decades. But it is in the recent years that, the inadequacy of routine planning process is felt and thence a serious revision of what has been achieved became the main question in professional circles. It is also provoked by the introduction of computers and CAD, dBASE and especially GIS software in the planning and design of urban projects. This new available technology has also contributed to studies concerning the process of the urban land use planning.

It is necessary to sketch out the classical traditions of land use planning process to explain the basic arguments of new methods of processing. The main process model of urban land use planning was introduced by the Master Plan of Tehran. This master plan was developed during 1965-69 in a joint venture co-operation of The American Victor Gruen Associates and The Iranian A.A.Farmanfarmaian & Partners Consulting Engineers. The Master Plan of Tehran, which was the leading reference in Tehran's urban development projects till 1987, was established according to the planning process applied in American middle sized cities of the time. This model was based on a universal common approach of urban planning, that schematically is described in "Planning Design Criteria" handbook of Joseph DeChiara and Lee Koppelman (1969 version). Since then, the Master Plan of Tehran and the mentioned handbook have become the bible of Iranian urban planning consultants, and many other master plans for large or medium sized cities in Iran have been drawn up essentially by the same approach.

But none of these master plans were successful in adapting to the present state of the cities and to control and orient their future physical developments. Studies considering the lack of success have proved some methodological shortcomings were responsible. As mentioned, the main process model of urban land use planning has been applied successfully in the developed countries, therefore the problem must be laid in its application in our country. Further studies confirm this finding. That is because the mentioned model has matured in a developed country's environment which is very different in developing countries.

In very general terms, this urban land use planning involves the redistribution of urban land uses due to social, economical and environmental needs. The applied methodology for this model of land use planning process consists of two principal phases. The first phase essentially includes field surveying and data gathering. In this phase the major problem lies in the working procedure of data gathering. This working procedure is not able to recognise the determinant development factors and give a clear image of the city's present state, while it is useful to describe broad and general tendencies at work in the patterning of urban land uses. In the developed countries, specialised institutions produce the necessary information and its related data in a systematic way. These can be added directly to a land use planning procedure to understand the present state and its determinant factors in physical formation of the cities. Generally, this does not hold true, in developing countries. Consequently the identifying of affecting factors is usually estimated by some samplings, and so, as a result, the analysis of urban land use structure is imperfect and in many respects it is an oversimplification. So the result of this procedure, especially in physical aspects has no major relevance for the land use planning process. The second major problem manifests itself in the second phase, where the proposal must be materialised. For example, in the processing stage concerning space requirements, appropriate standards are needed to set down the plan. Appropriate standards can only be provided where locally prevailing culture/nature relationships are thoroughly studied and have been adopted by a rational decision making procedure. Once again, this is not so in developing countries. Alternatively, the utilisation of the standards of developed countries are preferred, which again are not invariably appropriate. Further uncertainties follow this procedure of land use conceptualisation. One of the most important is the uncertainties concerning the testing out of various locations for size and eventually arriving at proposals reflecting the best possible balance in land utilisation. This must be done in assent to analytical procedure throughout the whole sequence of study, but the procedure described does not provide an appropriate base for a rational conclusion. The importance of this inappropriate state is stressed considering the statutory character of these land use plans.

Emerging methodologies in GIS application in urban projects:

Two basic proceedings concurrently supported the elaboration of a new approach in urban planing procedure.

The first proceeding consists of the application of GIS in preparation of urban planning projects. In recent years CAD and more recently GIS software have been introduced to urban planning agencies in Iran. The initial utilisation of such software is concentrated in mapping procedures. In particular, the GIS software is used to prepare the thematic maps of urban projects. The land use map and some related maps such as types and states of structures or the land-use intensity site ratings etc. now generally use GIS software products.

In a farther attempt for the first time in Iran, under the auspices of an important urban project a successful link between detailed statistical information and urban planning base maps were established. The project was "The physical development Plan of Eastern Part of Tehran"1. The results of the recent consecutive census (in digital format) are available from The Statistical Centre of Iran. The most detailed scale of this statistical information is the census block2. Each of these blocks is consecutively coded within a census tract. So by transferring the blocks and related codes to the prepared digital maps we could merge the statistical information. This information consists of nine basic fields considering the population indicators in two consecutive censuses (number of population: by sex, by age groups, by the literacy rate, ..... number and size of households,.......,employed, unemployed,....). The possibilities of studying the evaluation of population indicators in a detailed urban map give an extensive foundation for different demographic analysis in an urban area. This moreover opened the way for other similar attempts. The housing information gathered in the mentioned census are also merged. Subsequently the stand is completed with the land use information included in establishments' statistics. These compositions provide the base for more detailed study of urban evolution reflecting on location and arrangement of land use. It also serves as an appropriate data bank to produce the requisite indicators for urban planning purpose and its related data in a systematic way.

Where previously there was a lack of appropriate information, now the planning staff had another problem; "How to deal with so much information?". Accumulation of data within the GIS databases, which, had been done for mapping purposes, also opened up the vast scope of GIS for analytical processing for land use planning. Also in this field the GIS computational capabilities have provided opportunities for modelling the prototypes of urban land use planning procedures, and even possibilities of observing the results through virtual simulations. These opportunities have advanced the exploration of new ideas and the elaboration of new applicable theories.

The second and the most major proceeding involves the land use planning field. Some theoretical studies concerning the process of more appropriate methods for land use planning are in course of materialisation. A notable field in these studies involves land use determinants. About 2000 urban land uses have been identified during recent statistical survey of establishments in Iranian cities. In a parallel study using the field notes of land use surveys of seventeen Iranian cities the distribution of these 2000 land uses in the cities are studied and considered with city size and rank, city' s regional function, population densities, and so on. Also these land uses have been sorted in different ways, applying the criteria relevant to land use planning. These findings showed four major types of land use patterns for cities. In this study each land use is considered in terms of its urban activity.

The indicator function of urban land uses:

Analysis of the land use pattern, with regard to the major functional areas of land use in a city, and how they change over the years, is the basis of urban ecology. Urban ecology is a term, that the sociologist has adapted from the biological sciences to describe the physical change processes in the city. It concerns the physical, spatial, and material aspects of urban life. It is also connected with the interrelation of living things and their environment. These ecological factors of land use thus can be explained in terms of "ecological processes" with their physical context and "organisational process" with their social structure context.

In other words, this approach considers the existing land use pattern as an outcome of the interacting determinants. The main idea is that in analysing the pattern by considering related contexts, the determinants and their way of action can be identified. It is then possible to view the changes through the time and the evolution of context. In a farther development some land uses or combination of a set of land uses could be recognised as indicators for analysing the land use pattern.

For example, in Iranian urban agglomerations a grocery store indicates the existence of a neighbourhood unit and its function area indicates the boundaries of that neighbourhood unit. The periodical investigations had proved that when there were two grocery stores in one neighbourhood unit, the second was obliged to close due to lack of trade. On the other hand, in a neighbourhood unit where even due to specific regulations the establishment of stores is forbidden, investigations show that an unofficial grocery store could exist. Subsequent studies confirm this dynamic relation to the functional area. At the same time the space requirements and localisation factors could be entrenched in relation mainly to the population density of the area, and some other relevant criteria. So a map of grocery store distribution could show the formation of neighbourhood units in an urban area.

Further investigations show that generalising the grocery store experience in larger domain could be defined only in specific land use clusters in relation to urban respective hierarchical divisions (neighbourhood unit, community, sub district, district). Also it must be noted that, some slightly varying cluster combinations due to city rank must be adhered to. Again a map of the distribution of the aforementioned clusters could draw the hierarchical pattern of urban divisions.

This indicator function has considerable appeal in land use analysis and planning procedure to cope with the scale and rationale of the ever-expanding horizons of urban planning. It also produces vast and important factual references which are necessary to these professionals interested in physical aspects of current urbanisation.

In the project mentioned earlier, the "Physical Development Plan of Eastern Part of Tehran", these sets of indicators could outline the formation of hierarchical land use pattern reflected by social and physical context. Also associated with the social processes, land use indicators could breakthrough the identification of distinct cultural areas, islands of ethnic groups, areas of high religious practice, and so on. The extent and rapidity of the sorting could cover all aspects of land use pattern as a function of all attitudes, decisions, and actions at stake. They frequently involve such matters as deed restrictions, zoning, tightness of the housing market, cultural ties, location of place of work, school environment, and so on.

Even more some sets of land use could replace the insufficiency of economical or social indicators relevant to land use analysis. For example where the detailed statistical data about the distribution of income groups in urban areas are not available, the gradient concentration of pastry and flower shops could indicate the average income of surrounding residents.

One of the major achievements in the preparation of such an effort could be the producing of the most appropriate standards in an emerging field of study, among the vast wealth of material available. In order to maintain a manageable form it is therefore, necessary to experiment and select the facts that would represent a real criterion rather than to attempt the inclusion of imagined information.

An analysis system of land use patterning

The grocery store experience and its further development lead also to other types of sorting. In another experience dealing with the land use planning for a new development plan, land uses are sorted due to their potency of localisation in urban geographical context. The criteria in this sorting were drawn out from land uses respective localisation in an existing pattern due to their functionality area. The results of this sorting are classified in dynamic, semi-dynamic and passive due to the variance calculating methods.

Each dynamic urban land use locates itself in an urban context according to a direct relation to its area of function and potency of its functionality. The spatial localisation of these land use are usually the central areas of their functionality boundaries. The periodical investigation of dynamic land use locations has proved that any change in their zone of function or their potency of functionality has contiguously affected their localisation in urban context. In a gradient manner due to the extent of functionality area, mainly the commercial, private office buildings and some governmental or public land uses could be categorised as dynamic. Governmental and public land uses usually benefit in special Iranian land acquisition regulations, that is why some of them are categorised as dynamic. This active relation introduces an accurate functional pattern of dynamic urban land uses.

The semi-dynamic land use locates itself in an urban context with an acceptable relation to its zone of utility. The potencies of functionality of semi-dynamic land uses are regularly determined due to governmental or some public interventions. The spatial localisations are usually in a range of their zone of utility but are far from the central areas of dynamic land uses area of functionalities. Public schools, general hospitals and other public or private similar services are usually categorised as semi-dynamic.

Passive land uses have a poor potency of localisation due to their area of function. In the ongoing urban life in Iranian cities in recent years, these are usually the quasi-public utilities which are not supported by any specific regulations or due to restrictions, the private sector is not interested. Cultural, entertainment or recreational centres are among the main passive land uses.

In urban land use planning procedure this sorting gives the planner the criteria to intervene to support the appropriate land use redistribution. Its usefulness rests on its approach in giving the planner, the basic pattern of information required to aid in solving the many varied and complex problems of our cities. Also, the material which is comprehensive in scope, will be highly valuable to other disciplines related to urban planning.

Dynamic, semi-dynamic, and passive land uses are viewed as a group. These three modes of process offer a means of understanding the ongoing aspects of the patterning of the city. A land use table is produced by interactively contemplating these modes in relation with land use functional categories and moreover, jurisdictional considerations. This table which mainly deals with space requirement, also indicates where and in which parts of categorised land uses special consideration or planning type interventions are needed. These processes can also be used to describe the politic of change in the patterning.

The land use table referred to previously is also extended for hierarchical urban divisions (neighbourhood unit, community, sub district, district). For each division a specific land use table is assembled containing the land uses with a similar area of function. These tables indicate how to deal with every category of land use by divisions (classified functional areas). Describing the present situation of land use distribution in each stage of urban hierarchical division is also possible by using these tables.

The analysis of land use patterning due to a city's regional function is also possible by considering the regional function area of related land uses. Even the standing of the city in a regional or national urban system could be determined by analysing the combination of related land uses with regional function areas.

Elaboration of a new approach for land use planning

The results mentioned and some from other experiences have established a useful and pictorial way of describing broad and general tendencies at work in the patterning of urban land uses. More recent work seeks more complex explanations of land use patterns which also take into account irregularities that tend to develop in land use patterns. The most important effect is that through similar experiences proper indicators to each urban society can be defined and special standards can also be determined. These experiences which at first are propounded only as a diagram to explain observable tendencies in the internal structure of the city could become bases for elaboration of a new methodology for urban land use planning.

An attempt to settle an applicable procedure following phases of land use planning based on land uses combination analysis is realised. This procedure begins from the specific preparations' phases to regional consideration stage and from strategic development plans to details of site planning. The included diagram shows the concise graphic explanation of the procedure.

This procedure is still far from becoming a complete methodology of resolving problems of our contemporary cities. It needs elaboration, and probably modification, on the basis of empirical investigation before it can become a basic operationally useful methodology of urban land use planning procedure. It requires experiences to define clearer indicators drawn up from differentiation between factors explaining the structure and dynamics of positioning in land use pattern. For example, some indicators probably may include aspects of "natural" market forces; others in terms of overcoming the "friction of space", the development of technological advances; and still others in terms of community values and legalistic controls such as zoning.

But the application of the proposed procedure in the above mentioned project, and in some other urban projects, have successfully proved its practical usefulness. The implications of these processes have been explored to explain, in descriptive terms "what is" or "what has been", the context and determinants of urban land use patterns. Even at its modest stage it has oriented studies towards the operating needs of the city planner in recognising and providing for land use planning and land development practices.

S.Mohammad BARAR
URBAN STUDIES CONSULTANT (Individual Consultant)
No. 5, Twenty First Street, Park Ave
Tehran 15139

Telephone & Fax : ++ (98 21) 8718288

1 The city of Tehran due to the latest Master Plan is divided into five parts, and the Eastern Part is one of the most concentrated urban areas with about two million inhabitants and an area of 1338 hectares. The "Physical Development Plan" is a more detailed version of the "Master Plan".

2 A census block is usually a well-defined rectangular piece of land bounded by streets or roads. However, it may be irregular in shape or bounded by other features.