GIS applications for Urban Planning - A case study of Tinidivanam Town, Tamil Nadu

Dr. S.P.Sekar
Assistant Professor, Institute of Remote
Sensing Anna University,
Chennai 600 025.
E-mail: spsekar@md3.vsnl.net.in/spsekar@hotmail.com

Abstract
The primary function of information in urban planning and management is to provide factual status and secondly to support analysis and decision making on environment. An assessment of the user need of urban planning reveals that planner's success or strength lies in interpreting and assessing the interrelation between various functional elements on a temporal and spatial format of urban form. Planning and implementation of Tindivanam Town draws various sources of geographic and attribute data. Geographic data for this town are in different scale, such as Master Plan from village maps (scale 1: 7920), Detailed Development Plan from Field Measurement Book (FMB) (scale 1:1584), line map from aerial photo (scale 1: 2500) and various facility location in the village map. Temporally these maps are varying dates and non-geo-referenced. A task was set to built GIS data base for Tindivanam with data integration for query out-put as its focus. It was found from the case that GIS has the capacity to efficiently integrating spatial data base for urban planning. However, it was also noted that the spatial errors from the original paper maps do severely cause limitations of information integration for urban planning. The efficiency of GIS in urban planning could be achieved only if reliable(perhaps with GPS), latest spatial data with moderate scale is constituted on rational basis.

Introduction:
Increase in population size and industrialization of urban areas in India draw the focus of urban planning problems as national agenda. Added to this is the increasing number of villages grown-up at faster rate as urban centers. Planning and management of urban centers, therefore, needs quicker reactions to the ground truth as well decisions made dynamically matching to the ground truth and not on static information base. One of the prime requirement of such a planning process is the information supply to meet the challenging task to identify planning problems, preparation of plans and implementation. All these three stages are of either long term strategic nature or short term action plan. Traditional information back-up of planning department are paper based, wide gap between the ground and paper, time and cost consuming efforts to update the information (Sekar, 1997). Geographic Information Systems (GIS) is a vehicle through which planners can be backed with geographical and attribute data for analysis and decision making process with fast update and analysis. Building-up of GIS database fir Tindivanam Town of Tamil Nadu is a pioneering such case taken-up by the Commissionerate of Town and Country Planning, Government of Tamil Nadu.

Tindivanam Town:

User Department's Need Assessment:
The main objective of the project was to integrate different scaled information to common base as to allow calling and comparing spatial and attribute information across themes. The details of the themes and its attributes ate shown in the table 3.1.


Table 3.1. Themes and attribute data base for Tindivanam Town - 2000

Sl.No.	Name of the Theme	Scale of the Map	Major attribute	Source data
1	Master Plan (Existing and Proposed Land use)	1: 7920	Land-use, survey number	Village maps complied to form LPA
2	Detailed Development Plan (DDP)	1: 1584	Land-use at micro level	FMB records complied to form DDP area
3	Cadastral maps	1: 3960	Survey number	Village and FMB maps
4	Line map from aerial photo (1996)	1.:2500	Entity ids	From aerial photos
5	Social facilities	1:7920	User ids	Village maps and attribute data
6	Water supply	1:7920	User ids	On village map with ids

While the project was in development stage, discussions were held to assess the user's requirement. There are three basic user requirements were listed. One, to have digital data base of all the themes in a common scale; secondly, to analyses urban development process using cross theme data base. Eg. Building location and area called from line map overlaid on cadastral map of Detailed Development Plan and compute Floor Space Index (FSI) of that property; compare buildings from line map and land-use from DDP to validate the trend of development etc. Thirdly, to use the GIS data base for update and add further attribute data on each the theme from various agencies. The third task is an important activity of the Town Planning Department as they have the responsibility to prepare the development plan of the town. As of now, this department is handicapped with non-availability of geographical data such as power line, trees, buildings, slope etc. While preparing the development plan (Master Plan, DDP, Town Planning Schemes etc.) the Town Planning department invest time, cost and material for the survey of the town area keeping the revenue map at the background all the features need to be surveyed from the field.

It was anticipated that the integrated GIS data base would serve the purpose of all the three stages explained above. By which, the GIS data base would aid the Town Planning department in:

1. Preparing new or revise Master Plan
2. Preparing new or revise DDP
3. Analyzing the land-use pattern
4. Adding geographic and attribute data from other department Using it for planning permission
5. In analyzing land value and Tax assessment

GIS Data Base Design for Tindivanam Town
The primary task of GIS data base for Tindivanam Town is to identify the geographic base to which all the geographical data base be attached. The smallest scale of all the theme was Master Plan on 1: 7920 scale. The largest scale was the line map from aerial photo of 1:2500 scale. The user department requirement is that all the base need to be referred to Master Plan for analysis and decision making. As conversion of large to small scale have better accuracy and so the user department's requirement of comparing all the themes to Mater Plan base. It is also noted that no theme is geo-referenced and in different scale. As a first task, it was decided, to geo-reference at least one theme and convert it to 1: 7920 scale which would allow to overlay Master Plan on it. The routine practice of geo-referencing tics, it was realized, would not help to orient the base exactly, the topo-sheet of 1: 25000 was scanned and enlarged to 1: 2500. Keeping this at the background, the digital line drawing was oriented to the topo base using AutoCAD. As AutoCAD allows objects to rotate, move, scaled, the line drawing could be adjusted comparing all the features such as road, railways, build-up areas and tanks. From this, the geo-referenced tics were prepared using the latitude and longitude of the topo sheet.

All other themes like Master Plan, DDP, water supply network, location of social features were transformed using AutoCAD to the common geo-referenced tics. Later, all the themes were exported to PC ARC/INFO for building topology and adding attribute data to all polygons of each theme. To handle better out put quality, each of the theme was plotted to master Plan scale.

User department feedback
Theme wise GIS data base were submitted to the user department in one hard copy and in CD. When the feed back was collected, the user department felt that the data base do allow analysis and query across the theme but with limited positional accuracy between themes. Positional accuracy of line map was better with DDP that with the Master Plan. It is surprised to note that the positional accuracy between Master Plan and DDP was relatively poor. It had happened due to the following reasons:

1. The source map for each theme was drawn from various scaled maps with different accuracy
2. Age of the geographic features in each theme various
3. Type and method of projection adopted by each source theme were different
4. Method of original composition of each theme's geographic feature were different

Enhancement of GIS data base It is critical to review the utility of the GIS data base generated of TIndivanam Town. Comparing to the original user department's need the out put was not fully met by the GIS data base. It is also clear that the errors introduced by the base of each theme were the cause for inaccuracies. it goes back to the vicious cycle of first developing accurate base map and then develop GIS on it. Each departmental spatial resolution and dating of spatial and attribute data swings between each property (eg. water supply) and to wards (eg. ward committee) and to town level (land use analysis). It is time to constitute a statutory body to look into these needs of each department and lay down norms and standards for spatial data base. This has to be viewed in the availability of high resolution satellite imagery accessible to user organizations at moderate cost and closer time interval (spaceimaging.com). It may lead to catastrophe of worst than paper map each development handle at present which are at least visible, being hard copy, for comparison even at different scale.

Acknowledgement The author wish to thank the Commissioner of Town and Country Planning, Government of Tamil Nadu for sponsoring the project of GIS data base for Tindivanam Town, which form the basis for this article. However, the expressions made by author is of his own and not represent the development's view.

References
DTCP (199 ) Master Plan for Tindivanam Local Planning Area, Directorate of Town and Country Planning Department, Government of Tamil Nadu. Sekar S.P. (1997) " Development Control as a source of Planning Information : a GIS model for Chennai Metropolitan Development Authority" Unpublished Ph.D. Thesis, School of Architecture and Planning, Anna University, Chennai.