Operational Urban Sprawl Monitoring using Satellite
Remote Sensing: Excerpts from the Studies of Ahmedabad, Vadodara and Surat, India*
P. Jothimani
GPS/GIS System Division,
Hitachi Zosen Information Systems Co., Ltd.
7-37-10, Nishi-Kamata, Ota-Ku, Tokyo 144, Japan
Tel: 81-03-5711 5325 Fax: +81-3-5711 5371
E-mail :jo@gps.hzs.co.jp
Abstract
Urban sprawl mapping and monitoring is one of the operational applications of satellite remote sensing data, irrespective of its spatial and spectral resolutionof the satellite-borne sensors. From the earliest data (Landsat-MSS) with comparatively coarse resolution to the present high spatial resolution data (IRS-1C panchromatic), detecting the changes in land cover and its use, especially the delineation of built up environment has been proved efficient. The visual interpretation techniques which has an edge over the digital analysis and interpretation of the built-environment has been advocated in conjunction with the topographical maps to operationalize the techniques. This paper presents an attempt in this direction to map the sprawling trends and changes in the urban core using topographical maps and IRS-LISS II data with the case studies of ahmedabad, Vadodara and Surat (of Gujrat state) cities of India. The SPOT data has been used as Ground-truth control data in most of the situations. It is also evidenced that even with very coarse spatial resolution of the satellite borne sensors the data also being discussed and viewed as a bottleneck for research and other purposes of study of urban areas.
Introduction
Urban form and the structure of Indian cities are mostly evolved through the ancient urban core as well as the current sprawling urban corridors into the rural fringe agricultural areas. In the emerging scenario in the world it is estimated that around 50% of the total global population shall be urban by 2000 A.D. and 2/3 of these will live in cities and towns of less than 1 million (World Resources Institute, 1995). In India alone 1/3 of country' total population will become urban.. So it is essential to have updated information on urban growth patterns and its impact on the living environment. It is also observed by various studies that current trends of spatial urban growth pattern is haphazard along the rural-urban fringe areas. So there is an obvious need for periodic studies on current phenomena of growth patterns. The haphazard growth patterns along the transitional rural-urban (rurban) areas as well as the densely populated dynamic urban core is of great concern to the urban administrators and planners. In order to provide basic amenities and infrastructure for complex urban environment, the up-to-data information pertaining to the dynamic processes within and around the city regions shall be of immense value and use to the planners and
Administrators. Satellite Remote Sensing, with repetitive and synoptic viewing capabilities as well as multi-spectral capabilities is a powerful tool to map and monitor the emerging changes in the urban core as well as in the peripheral areas of any urban entity. Satellite date obtained through the sensor, even with the coarse spatial resolution (minimum unit of detestability) in conjunction with the topographical maps of older origin. Hence the studies recent stage of urban regions. These are comparatively easier task in urban land use oriented mapping than monitoring land use change detection or monitoring in the urban core.
Satellite Data Based Urban Land Use Inventory
Multi-temporal and repetitive satellite data offer unique opportunities for mapping and monitoring some of the elements of urban core, its dynamics and the resultant urban structure. The complexities and elements of urban dynamics as well as the required satellite data characteristics are controlling factors in urban inventory and analysis. With careful analysis and assessment of satellite data capability, and also with the experience gained through earlier studies with IRS satellite date, this study is limited only to the delineation of major classes in urban core as well as urban sprawling trends. SPOT satellite data (MLA) have been used and analysis. Satellite data based mapping and monitoring has its own limitations in terms of monitoring the elements of urban dynamics. At very coarse or preliminary level of mapping using the satellite data would be delimitation of built-up space, vacant/open spaces, recreational zones, industrial sites and other emerging suburban zones. The nature and interpretability of satellite land data decides the accuracy levels as well as the possible constraints in identification of urban features. Very fine resolution in the order of 5 meters will enable us to map urban land uses in level III or more (Welch, 1985). This attempt of delimiting the sprawling suburbs, is to identify the zones of growth as well as the emerging suburban land uses such as developing in industrial/residential cluster and dynamism in rural urban frige agricultural areas. These thus help in identification of typical and use zones and its territorial association to its urban core of the region shall enable to derive the emerging spatial urban structure. These process of evolution with reference to time and space forms essential component of the current dynamic phenomena of urban structure. (Figure 1.)
Figure 1. Functional requirements for Operational Urban monitoring and bottlenecks
Operational urban sprawl monitoring requires a functional system (Figure 2.) that enables consistent mapping and monitoring. It has been widely observed that data dissemination policies become a hurdle in a research and academic environement.
Figure 2. A typical sketch of a settlement environment and its morphology
