Urban Sprawl Assesment: Entropy Approach

Urban Sprawl Assesment: Entropy Approach

SHARE

Sulochana Shekhar
Sulochana Shekhar
Lecturer in geography
National Defence Academy, india
[email protected]

The Remote Sensing data, GIS combined with Shannon’s entropy has proved to be efficient in monitoring and measuring the urban sprawl of Pune, a developing city in the Indian state of Maharashtra

The monitoring of urban development is mainly to find out the type, the amount and location of land conversion for future planning. Although various studies have been dedicated to measure and monitor the growth and sprawl of urban form they have limitations in capturing the characteristics of urban sprawl. Here is an alternative technique – the Shannon’s entropy – specially to measure the sprawl is developed within the integration of remote sensing and GIS. The advantages of the entropy method are its simplicity and easy integration with GIS.

Hence an attempt has been made to make use of entropy method to analyse urban sprawl of Pune city, in the state of Maharashtra, which is a part of fast growing urban agglomeration in India and to prove that the technique is useful in mapping and monitoring the urban sprawl patterns.

Study Area
The study area (Figure 1), the Pune city lies between latitudes 18°25’N and 18°37’N and longitudes between73°44’E and 73° 57’E and cover an area of 243.96 sq km. Pune is located in a saucer shaped basin at an average altitude of 560m from mean sea level and surrounded almost on all sides by hills at different altitudes. The ground slope rises gradually from the river, with RL 530 metre (1,750ft) towards the hills with the highest RL 697 metre (2,300 ft) at the Vetal Hill. The slopes become steeper close to the hills.

The city is very fortunate in having in addition to the beautiful hills a number of rivers flowing through it. The Mutha River enters the city from southwest, the Mula River from northwest and the Pawna River from the north. After their confluence to the west of Dapodi, the Mula and the Pawna join the Mutha River near the Sangam Bridge and these rivers then take an almost eastward course and leave the study area on the east of the Mundhawa village. The climate of Pune is typical monsoon. The temperature ranges from 15°C to 35°C. The average rainfall is 70cm with more rain during southwest monsoon period. Pune is one of the fast developing urban agglomerations in Asia and ranks eigth at national level (census 2001). It has grown quite haphazardly. The present growth is due to various factors such as industrialisation, location of various Central and state Government establishments.

Database
Digital data of IRS 1D LISS III of 5th December 2001, pertaining to path-095 and row 059, Survey of India toposheets (Index No. 47F/14, 47F/15) on 1:50,000 scale were used for the purpose. Maps and other collateral data were procured from Pune Municipal Corporation (PMC), Town Planning Office, and Mashal NGO group (who were involved in the preparation of city development plan). The demographic details were taken from census abstracts.

Methodology
The digital remote sensing data was processed and geo-referenced in Erdas 8.3.1 software. Initially the toposheets were scanned and geo-referenced and used as base for image registration. The geo-referenced FCC image (Figure 2) was further enhanced by using necessary enhancement techniques. After that visual interpretation of image was done to identify the major land use classes. The enhanced image was classified on the basis of samples collected from different classes. Maximum likelihood classifier of supervised classification (Figure 3) in Erdas was used to classify the image into four major classes and again they remerged into two main classes as built-up and Non- built-up area.