INTRODUCTION

Urban growth is  a  spatial  and  demographic  process,  involving concentration of  human population with higher level of economy [37]. While urbanisation is a dynamic complex phenomenon involving large scale changes in the land uses at local levels. Analyses of changes in land uses in urban environments provide a historical perspective of land use and an opportunity to assess the spatial patterns, correlation, trends, rate and impacts of the change, which would help in better regional planning and good governance of the region ([37][7]). Structural composition and rate of growth of most Indian metropolitan cities or tier 1 cities have an aggregated core region and cities are expanding into the rural fringe areas. Due to burgeoning population and concentrated developmental activities, most of Tier 1 cities have exceeded their carrying capacities, which is evident from poor assimilative capacity (higher levels of pollutants in land, water and air), supportive capacity (lack of appropriate infrastructure, traffic bottlenecks) and lack of basic amenities (treated water supply, electricity and sanitation facilities. This necessitates policy measures to decongest tier I cities. This entails providing an alternative region for development and hence the current focus is on Tier II cities. Advance visualization of urbanisation process will aid in better regional planning to provide basic amenities and infrastructure.  Urbanisation being the complex and dynamic process, planners and city developers need to monitor and visualize the growth pattern and land use dynamics in the urban and peri-urban areas of the Tier II cities. Otherwise, peri urban regions prone to the sprawl that would be devoid of basic amenities and inefficient and consumptive use of its associated resources.

Mapping and monitoring sprawl helps in identifying the environmental degradation process as well as to visualize the future sprawling growth patterns [3]. Several studies in this regard ([6] [36] [13] [5] [17] [15] [19] [11] [33] [25]), have quantified the sprawl through the diverse techniques. The most common approach is to consider the spatial and temporal dynamics of the regions with impervious surfaces [15].

Many studies have employed large number of indicators, including land-use conversion, population change and energy requirement [2]. Other researchers focused on measuring sprawl through the use of population data as an indicator ([35] [37]). These patterns of sprawl on landscapes can be detected, mapped and analyzed using remote sensing data along with certain image processing ([32] [14] [26] [12] [37]). Thomas [29] considered Shannon’s entropy model as a good measure of urban sprawl, i.e., the degree of spatial concentration and dispersion exhibited by a geographical variable. Various researchers have used shannon’s entropy, ([1] [17] [10] [37] [7]) which reflects the concentration of dispersion of spatial variable in a specified area/zone, to measure and differentiate types of sprawl. This is why for this study Shannon’s entropy has been used to assess the urban sprawl. Further, to understand the growth dynamics and the pattern Landscape, metrics as indicators have been used.

Landscape metrics or so called spatial metrics are numerical measurements that quantify spatial patterns in the form of compactness/edge/shape of land use patches of a geographic area [18]. There is a large number of studies that have used these spatial metrics in order to understand the pattern of urban landscape ([22] [23] [16] [8] [9] [37]). Landscape metrics currently used in satellite data analysis have a long history of usage in various fields such as ecological modeling ([20] [4]). Herold et al., [21] defined and described the function of spatial metrics as digital analysis measurements on the thematic-categorical maps that have a spatial heterogeneity at a particular resolution. Spatial metrics have found important applications in quantifying urban growth, sprawl, and fragmentation [34] [24]. Angel et al., [31] demonstrated five metrics for measurement of sprawl. Ramachandra et al., [37] have successfully applied the metrics and found very useful in understanding the urban growth process. Henceforth, spatial metrics have been used in the study to understand the process and pattern of growth.

In the present study, an attempt has been made to study the impact of growing urbanization on the land-use and land-cover pattern of Raichur city and its effects on the rural fringe considering a 5 km buffer region. To examine  the urban growth distribution and variation outward from  the city center and model the growth, gradient approach and landscape metrics are employed.