Abstract
Flats or high-rise residential buildings are essential for the residential purpose of a modern city. But there should be some regulations on the constructional activity of flats and zones of potential areas shall be delineated. GIS provides a very efficient tool for doing this delineation. Present study is on identification of suitable sites/areas for constructing high-rise residential buildings in Thiruvananthapuram City. It is done by applying various conditions on different data sets of the city in the GIS environment of ARC/INFO. The suitable areas are again prioritised based on the residential density. A total of 20sq. km area is identified as suitable out of 81 sq. km, the total area of the city. Based on the results zoning regulations have to be enforced by the respective departments or agencies. In short the study demonstrates the use of GIS for the efficient and effective utilities development planning of a city.
Introduction
The developmental process of a city with far-reaching physical, social and economic consequences has impact on the community. This definitely calls for a dynamic planning support system that ensures efficiency in data handling, processing and presentation. In fact GIS has provided a strong tool for preparation of a variety of thematic maps to support the development plan proposals as well as present such proposals in a visual form which is more comprehensibel for people, planners and developers. The use of GIS and Remote Sensing techniques is now gradually picking up in all the sectors of human life.
The high rise residential buildings or flats are essential for residential purpose in most of the modern cities since the flats save the space of ground, cost of construction, cost of infrastructures and cost of utility services. The site selection of flats in a city is very crucial when economic activities can be related to the spatial location of residential flats in terms of money and vice versa.
Scope of the study
The strategic locations of flats facilitate easy traffic of people from home to work places, avoiding wastage of time, money and energy and have minimum impact on the economic base (resource base) of the city. So there shall be some regulation on the constructional activity of high-rise residential buildings (flats). Zones of potential areas shall be delineated and GIS (Geoinformatics) provides a very efficient and fantastic tool for doing this delineation. The analysis capability of GIS can be streamlined for this purpose. "Narrowing Down the Area of Interest' by applying various conditions is a very relevant method in GIS for selection of suitable (potential) sites. GIS also provides a platform where various types of data and themes can be integrated together and get analysed to derive the fruitful output.
In this study, the suitablility analysis based on multi-data is done. Ward is taken as the basic spatial unit and existing high-rise residential buildings located in the city map prepared by the Department of Town and Country Planning serve as a database. This study will help to integrate statistical as well as graphic data from various sources (Water Authority, Census Departments) and to organise systematic GIS-based information system for the Master Plan of Thiruvananthapuram City.
About the study area
Thiruvananthapuram, the capital of Kerala State, is a coastal city located at 8025I North Latitude and 76055I East Longitude. Thiruvananthapuram is a city of hills and dales. The city gained corporation status in 1940, which presently consists of 50 wards with a total population of 5,23,733 as per the 1991 Census. The area is primarily a service area with more than 30% of the total workers are office workers. Land use refers to the spatial distribution of city function. The predominant land use is residential. The existing water supply system was designed in 1928 and put into commission in 1938. There are 4 zones for the present water supply system, namely, New central zone, Low level zone, New Thirumala zone and New Peroorkada zone. The city underground drainage scheme is designed to serve the population with 5 blocks, namely, A, B, C, D and E. From these blocks the sewage is being drained into a pumping stations and then to the treatment area at Paravankunnu near Valiyathura.
Objectives
The goal of the study is to identify the spatial distribution of existing high rise residential buildings (flats) and to identify suitable/potential sites for constructing high rise residential buildings in the Thiruvananthapuram city, optimising the resources, infrastructure, networks thereby eliminating the imbalance in the future population distribution.
Methodology
The methodological procedures of the study involve data collection or acquisition, data preparation, data input, data editing and verification, storage and management, analysis and output presentation.
Data Acquisition and Preparation
The Survey of India topo-sheets contained geographic elements such as map co-ordinates. This along with city map prepared by the Department of Town and Country Planning is used as a reliable large-scale source map. Data sets have also been generated from the maps of Water Authority. Land use information is transferred from the draft plan (Development plan for Thiruvananthapuram02011) prepared by the Department of Town and Country Planning. The maps thus collected are retraced to obtain different thematic maps with the same boundary and registration poinsts (Latitude and Longitude).
The acquired spatial data sets are organised or designed in such a way that the thematic layers Boundary, WArds, CBD, Land Use, Sewerage Zones and Water Supply Zones are prepared to store it as polygon entities. The theme Flats is prepared to store it as point. The layers viz, Water Course, Roads, Railway Lines and ShoreLine are prepared to store them as lines or arc data. Then, each thematic spatial layer is designed to contain different classes or types at second level and are represented using different codes. A set of secondary elements has been designed to be derived from primary elements for and from the different analysis procedures in GIS.
Data Input
Each of the prepared or designed thematic maps are scanned and their images are stored in the tiff format. Then the vector datasets are created through on-screen digitisation of the tiff images by bringing them to an Auto CAD R14 platform. All themes are vectorised and then exported to DXF format. The vector data is then import in to the GIS software package ARC/INFO as coverages.
Data Editing and Management
The error checking and editing was carried out in the input and editing module of ARC/INFO called ARCEDIT after creation of the spatial relationship or initial topology Cleaned coverages are then checked fro nodeerrors and labelerrors and corrected and saved as final edited coverage. The final topology is created using command BUILD. This feature attribute databse tables thus created will act as the basic framework to add user defined non-spatial attributes to the spatial objects in the coverages. For each geographic feature, there is one entry is one entry or record in the file. For each record, there are a number of kinds of attributes or items. After entering 'Info' the database management end of ARC/INFO, appropriate items are added to attribute tables of the different coverages. For example, 'ward number' is added to the PAT table of the coverage WARD. Different symbols are assigned to each feature in different coverages using Lookup Tables (LUT).
Analysis using ARC/INFO
The analytical procedures in the GIS environment are used to arrive at the objectives of the study. Various conditions are applied on the GIS database by executing various analytical tools in the software. The conditions set are.
- Preferred land use in residential.
- Sites having low net density.
- Sites beyond 100 meters from rivers, 50 metres from canals and 25 metres from thodus.
- Site within the areas partially covered by the existing sewerage system and within areas to be covered by the new sewerage system.
- Sites within the areas covered by the New Thirumala Water Supply Zone and New Perorkada Water Supply Zone.
- Sites beyond 250 metres from double-track railway line and 150 metres from single-track railway line.
- Sites beyond 500 metres from NH-Bypass, 250 metres from NH and 150 metres from SH.
- Sites outside CBD
- Sites beyond 500 metres from the seashore i.e., sites outside coastal regulation zone (CRZ)
To apply these conditions on the data, the analytical tools available in ARC/INFO are used. The tools used are UNION, INTERSECT, ERASE, BUFFER and RESELECT. The analysis takes the criteria that the next density is a factor that determines the potential sites, since the next density of above 30,000 persons/sq.km creates over crowding.
Then an item called suit_class is added to the attribute table of the resultant coverage to prioritise suitable areas. Areas. Areas having net density>1000 and <7501, net density>7500 and <15001 and net density>15000 and <30001 are selected with adding suit_class values 1, 2 and 3 respectively (to represent 1st priority, 2nd priority, 3rd priority) using RESELECT to get the final map. Finally a reclassification of flats based on the number of floors is done.
The tabular Analysis commands such as 'RESELECT' 'ASELECT', 'STATISTICS' are used in TABLES to select features based on attribute values and command 'CALCULATE' is used to calculate new attribute values. The final layouts for printing are created in the ARCPLOT Module. A presentation is also prepared in ArcViewGIS as a project with different views, tables, charts, and layouts. The project also incorporates the real images of some of the existing flats using the tool 'HotLink.'
Results and Discussion
As a result of the analysis the final suitable sites for the construction of flats are identified priority-wise based on the next density criteria. The resultant graphic data provides vast scope for applications in zonal regulations, planning, monitoring, area calculation and length calculations. As any information system, GIS gives provision for constant updation of the data. The analytical output could be updated either by ground surveys or by aerial photographs in terms of graphic elements. The computerisation of graphic data made the area calculation relatively accurate commpared to the calculation being done manually. To arrive specific information such as cadastral information, property assessment, consolidation of land and redensification etc this analysis is much useful.
Suitable Sites - Analysis
Priority-wise classification of suitable sites identified is done as below. First priority areas extend to 10 wards and constitute an area of 12.851 sq. km, second priority area extends to 8 wards and constitutes an area of 5.739 sq. Km and the third priority area extends to 3 wards and constitutes an area of 2.093 sq. Km. A detailed area statement is shown below.
Table 1: Classificationof Suitable Sites
| Priority classes |
No. of wards |
Area (Sq. Km) |
| 1 |
10 |
12.851 |
| 2 |
8 |
5.739 |
| 3 |
3 |
2.093 |
| Total |
21 |
20.683 |
| Priority Class - 1 |
| Name of Wards |
Area in Sq. Km |
| Ambalathara |
1.0.085 |
| Medical College |
1.469 |
| Pattom |
1.640 |
| Kesavadasapuram |
0.938 |
| Sasthamangalam |
0.375 |
| Kanjirampara |
2.057 |
| Pangode |
0.761 |
| Thirumala |
2.292 |
| Thrikkannapuram |
3.048 |
| Kalady |
0.186 |
| Total |
12.851 |
| Priority Class - 2 |
| Kumarapuram |
0.454 |
| Nanthencodu |
0.914 |
| Kuravankonam |
1.607 |
| Kowdiar |
1.376 |
| Vattiyoorkavu |
1.304 |
| CED Geoinformatics |
| |
|
| Nedumcadu |
0.022 |
| Thaliyal |
0.026 |
| Karamana |
0.036 |
| Total |
5.739 |
| Priority Class - 3 |
| Mudavanmugal |
1.902 |
| Poojappura |
0.082 |
| Kunnukuzhy |
0.109 |
| Total |
2.093 |
In the priority class-1, an area of 3.048 sq. Km is identified in the Thrikkkannapuram ward. Thirumala ward holds an area of 2.292 sq. Km next to the Thrikkannapuram ward. Eight Flats have sprung up in the first priority area.
While considering the second priority area Kuravankonam ward (1.607 sq. Km), Kowdiar (1.376 sq. Km) and Vattiyorkavu (1.304 sq. Km) are predominant. Six flats have sprung up in these areas. Priority class-3 areas are located in only three wards, namely, Mudavanmugal, (1.902 sq. Km), Poojappura (0.082 sq. Km.) and Kunnukuzhy (0.109 sq. Km). No flats have sprung up in the third priority areas.
Conclusion and Recommendations
The study confirms the utility of GIS technology in physical planing and spatial analysis in particular. Now it is possible to identify programmes, policies, proposal, and projects in efficient and rational way for every ward in the Thiruvananthapuram City, based on the results. The selection of variables that go as attributes of the map hae been assessed properly to arrive at the specific objectives of the analysis. In view of the speed, quality of data handling and the choice of scenarios alternative decision-making is thus made possible.
Inferences
- The analysis shows that there exists a strong relationship between the location and facility/infrastructure, at the same time people prefer high-rise residential buildings at some distance away from the CBD.
- Only 14 flats hae sprung up in the suitable sites, where more investment is needed for land development in terms of provision of urban infrastructure.
- Actually, the proximity to the CBD is an attraction although cost of land is generally very high towards CBD.
- Low-lying areas and paddy fields of the city are not yet utilised for building flats.
- Execpt the flats constructed by the Government, the other flats are being aimed to high-income groups promoted by real estate companis.
Suggestions for policy formulation
Disproportional development may cause rapid conversion of agricultural land/paddy fields/open spaces. To end this process this spatial analysis is to be used as a tool to estalish a relationship between population, occupation and the location of activities with demand for spae. The following policies shall be adopted.
- Priority areas identified in accordance with their net density ranges shall be the centres of redensification.
- Within the priority areas, availability of land, costs of land etc have to be considered further to promote the construction of flats.
- High-rise residential buildings zone thus evolved shall have direct impact on urban sprawl.
- Control measures have to be enforced to control the growth of flats in high-density areas.
References
- Burrough P. A. and McDonell Rachel A., 1999, Principles of Geographical Information Systems, Oxford University Press.
- ESRI, 1991, Understanding GIS-The ARC/INFO Method.
- Town Planning Department, 1998, Residential Flats - 1996 in City Corporations and Municipalities in Kerala.
