Rapid urbanization causes disorganized and unplanned growth of towns and cities. The pressure of an ever growing population becomes a burden on the limited civic amenities which are virtually collapsing. Asymmetrical growth of urban centres consumes agricultural land adjacent to these, resulting in lower agricultural productivity. Besides taxing the groundwater resources available for an urban centre, an increase in the paved area severely reduces the groundwater recharge potential, leading to situations which may truly be potential catastrophes. An understanding of the growth dynamics of urban agglomerations is essential for ecologically feasible developmental planning. With almost a third of India’s population already having become urban, it is necessary to acquire information on growth patterns of cities and how they impact the living environment. The current trend of spatial urban growth in almost all Indian cities has a haphazard pattern, particularly along the urban-rural fringe. There is an obvious need for continuously monitoring the phenomena of growth, and mapping and analyzing its patterns, since this is of great concern to urban administrators and planners whose concern it is to provide basic amenities and infrastructure for the complex urban environment.
Mapping urban growth by conventional methods is too tedious and a slow process, and by the time information becomes available to planners, it is already outdated and redundant since the damage has already been done. Satellite remote sensing data and application of GIS technologies provide an alter-native means of rapidly assessing the dynamics and development of sprawl so that timely action may be taken. Besides being flexible and extensible, the datasets are easily rectified, updated and may be used for other applications.
The present study was carried out using Landsat, IRS and QuickBird data to delineate the extent, pace and pattern of growth of the city area of Aligarh. The study reveals that the urban area has increased almost three times since 1971. The rate of land consumption for urban purposes was substantially moderate till 1980s, but in the 1990s witnessed a sharp increase in land consumption as compared to population growth. The city still does not have a sewage treatment plant, and of the estimated 40 mld (million litres per day) of sewage produced by a population of 7,89,529, only 27 mld is pumped out or diverted for irrigation purposes, while the rest pollutes the urban environment or contaminates the ground water resources. Land consumption for urban purposes in the last fifteen years is estimated to be 1.428 km2 per year. Besides, substantial land acquired by city dwellers for intended urban purposes along the urban-rural fringe has been rendered saline.