Assessment of Physical-Spatial Development of Ilam City Using Shannon Entropy Model and Holdren Sprawl Growth Method

Nowadays, with theincreasing importance of city development on the one hand, and the methods of city development on the other, the necessity to examine the pattern of physical-spatial development of Ilam City is clear. Rapid and irregular physical-spatial development of Ilam City in recent years has resulted in undesirable economic, social, and physical results. Therefore, considering these issues, the objective of this study is to evaluate the pattern of physical-spatial development of Ilam City. The study is looking to investigate the pattern of physical-spatial development of Ilam City using Shannon and Holdren entropy models. This study is an applied-developmental study and its methodology is descriptive-analytical. In this study, the statistical population is Ilam City.In terms of physical division, Ilam City is divided into 4 districts which are examined in this study. Using library study method, theoreticalfoundations of the research were obtained. Then, using field observation and after data collection from the comprehensive developmental plan of Ilam City, the annual statistical publication and categorizing these data, direct observation method was used for completing the missing data. Finally, by combining the data and using Shannon and Holdren entropy models, the exiting pattern of the city's physical growth was determined. The obtained data were analyzed using Shannon and Holdren entropy and a number of indices (i.e. population, gross per capita, area of each of the regions, and the total area of the city) were used for analyzing the models. Shannon entropy model was estimated for all four regions for years 1991-2012, and results of analysis for both decades were close to maximum entropy value, which indicates the horizontal sprawl growth of Ilam City in these decades. Holdren model was calculated for both decades (1991-2002) and the decade (2002-2012), and the result of analysis showed negative physical growth of Ilam City. The result of analysis of Holdren model for the 20-year period (1991-2012) is equal to 1.68%for population growth and -0.68% for physical growth. Therefore, it can be said that, compared to its population growth, Ilam City has been experiencing a negative physical growth in this period and the development of the city has been interrupted. Moreover, increasing population density, reducing gross per capita of urban land, and horizontal irregular growth (sprawl) of Ilam City are results of the Holdren model. Finally, in order to mitigate the sprawl and horizontal growth of Ilam City, infill development pattern (internal development) is recommended.