Grupo 1 Monitoring Urban Sprawl Using RS &Amp; GIS

download Grupo 1 Monitoring Urban Sprawl Using RS &Amp; GIS

of 18

Transcript of Grupo 1 Monitoring Urban Sprawl Using RS &Amp; GIS

  • 8/12/2019 Grupo 1 Monitoring Urban Sprawl Using RS &Amp; GIS

    1/18

    + Models

    JAG-168; No of Pages 18

    Monitoring and modelling of urban sprawl using remotesensing and GIS techniques

    Mahesh Kumar Jat a, P.K. Garg a, Deepak Khare b,*a Civil Engineering Department, I.I.T. Roorkee, India

    b WRDM, I.I.T. Roorkee, India

    Received 17 March 2006; accepted 3 April 2007

    Abstract

    The concentration of people in densely populated urban areas, especially in developing countries, calls for the use of monitoring

    systems like remote sensing. Such systems along with spatial analysis techniques like digital image processing and geographical

    information system (GIS) can be used for the monitoring and planning purposes as these enable the reporting of overall sprawl at a

    detailed level.

    In the present work, urban sprawl of the Ajmer city (situated in Rajasthan State of India) has been studied at a mid scale level,

    over a period of 25 years (19772002), to extract the information related to sprawl, area of impervious surfaces and their spatial and

    temporal variability. Statistical classification approaches have been used for the classification of the remotely sensed images

    obtained from various sensors viz. Landsat MSS, TM, ETM+ and IRS LISS-III. Urban sprawl and its spatial and temporal

    characteristics have been derived from the classified satellite images. The Shannons entropy and landscape metrics (patchiness and

    map density) have been computed in terms of spatial phenomenon, in order to quantify the urban form (impervious area). Further,

    multivariate statistical techniques have been used to establish the relationship between the urban sprawl and its causative factors.

    Results reveal that land development (160.8%) in Ajmer is more than three times the population growth (50.1%). Shannons entropyand landscape metrics has revealed the spatial distribution of the urban sprawl over a period of last 25 years.

    # 2007 Published by Elsevier B.V.

    Keywords: Remote sensing; GIS; Urbanisation; Land use; Modelling; Urban sprawl

    1. Introduction

    Accelerated urban growth is usually associated with

    and driven by the population concentration in an area.

    The extent of urbanisation or its growth drives the

    change in land use/cover pattern. Land use and

    landcover changes may have adverse impacts on

    ecology of the area, especially hydro-geomorphology

    and vegetation. The process of urbanization has a

    considerable hydrological impact in terms of influen-

    cing the nature of runoff and other hydrological

    characteristics, delivering pollutants to rivers and

    causing erosion (Gordon et al., 1992; Paul and Meyer,

    2001; Weng, 2001). Accurate information on the extent

    of urban growth is of great interest for the municipalities

    of growing urban and suburban areas for diverse

    purposes such as urban planning, water and land

    resource management, marketing analysis, service

    allocation, etc. Urban authorities and municipal

    corporations are required to devote more time, attention

    and effort to manage the use of land and other resources

    in order to accommodating the expanding population or

    other urban land uses. Urban sprawl monitoring and

    www.elsevier.com/locate/jag

    International Journal of Applied Earth Observation

    and Geoinformation xxx (2007) xxxxxx

    * Corresponding author. Tel.: +91 941 299 0808.

    E-mail addresses: [email protected](M.K. Jat),

    [email protected] (P.K. Garg), [email protected](D. Khare).

    0303-2434/$ see front matter # 2007 Published by Elsevier B.V.

    doi:10.1016/j.jag.2007.04.002

    Please cite this article in press as: Jat, M.K. et al., Monitoring and modelling of urban sprawl using remote sensing and GIS

    techniques, Int. J. Appl. Earth Observ. Geoinform. (2007), doi:10.1016/j.jag.2007.04.002

    mailto:[email protected]:[email protected]:[email protected]://dx.doi.org/10.1016/j.jag.2007.04.002http://dx.doi.org/10.1016/j.jag.2007.04.002http://dx.doi.org/10.1016/j.jag.2007.04.002http://dx.doi.org/10.1016/j.jag.2007.04.002mailto:[email protected]:[email protected]:[email protected]
  • 8/12/2019 Grupo 1 Monitoring Urban Sprawl Using RS &Amp; GIS

    2/18

    prediction are the basic information they need for long-

    term planning. For balanced development, municipal

    authorities need tools to monitor how the land is

    currently used, assess future demand, and take steps to

    assure adequacy of future supply. For a better planning

    of future urban development and infrastructure plan-

    ning, municipal authorities need to know urban sprawlphenomenon and in what way it is likely to move in the

    years to come.

    Unfortunately, the conventional surveying and

    mapping techniques are expensive and time consuming

    for the estimation of urban sprawl and such information

    is not available for most of the urban centres, especially

    in developing countries. As a result, increased research

    interest is being directed to the mapping and monitoring

    of urban sprawl/growth using GIS and remote sensing

    techniques (Epstein et al., 2002).

    Remote sensing is cost effective and technologicallysound, so is increasingly used for the analysis of urban

    sprawl (Sudhira et al., 2004; Yang and Liu, 2005; Haack

    and Rafter, 2006). For nearly three decades, extensive

    research efforts have been made for urban change

    detection using remotely sensed images (Gomarasca

    et al., 1993; Green et al., 1994; Yeh and Li, 2001; Yang

    and Lo, 2003; Haack and Rafter, 2006). These studies

    have been supported through either an image-to-image

    comparison or a post-classification comparison.

    The impervious (built-up) area is generally con-

    sidered as a parameter for quantifying the urban sprawl(Torrens and Alberti, 2000; Barnes et al., 2001; Epstein

    et al., 2002). Here, impervious area refers to the area

    consisting of residential, commercial, industrial com-

    plexes including paved ways, roads, markets, etc. Urban

    sprawl has been quantified by considering the imper-

    vious area as the key feature of urban sprawl, which can

    be obtained either from physical survey or through

    remotely acquired data.

    There are a variety of techniques used to measure/

    estimate the area of impervious surfaces. The most time

    consuming and costly, yet the most accurate is manual

    extraction of impervious surface features from remotesensing images through heads up digitizing. Point

    sampling can be used as an alternative to digitizing,

    despite this being time consuming and less accurate.

    Remote sensing pattern recognition approaches, such as

    supervised, unsupervised and knowledge-based expert

    system approaches (Greenberg and Bradley, 1997;

    Vogelmann et al., 1998; Stuckens et al., 2000; Stefanov

    et al., 2001; Sugumaran et al., 2003; Lu and Weng,

    2005; Mundia and Aniya, 2005) have been used in

    recent past to measure impervious area and urban

    sprawl. These require both moderate to high resolution

    remote sensing data as well as expertise to process and

    analyze. These data and analytical capabilities are often

    beyond the reach of many planners and decision makers

    at local level, especially in developing countries.

    Statistical techniques along with remote sensing and

    GIS have been used in many urban sprawl studies (Lo,

    2001; Lo and Yang, 2002; Weng, 2001; Cheng andMasser, 2003; Sudhira et al., 2004; Chabaeva et al.,

    2004; Jat et al., 2006). Urban growth studies have been

    attempted in several developed countries (Batty et al.,

    1999; Torrens and Alberti, 2000; Barnes et al., 2001;

    Hurd et al., 2001; Epstein et al., 2002; Li and Weng,

    2005; Jantz et al., 2005; Yang and Liu, 2005). These are

    some examples and similar applications also exist for

    other countries like China (Yeh and Li, 2001; Weng,

    2001; Cheng and Masser, 2003) and India (Lata et al.,

    2001; Sudhira et al., 2004; Jat et al., 2006). Statistical

    techniques like multivariate regression has been used todetermine the relationship between the percent imper-

    vious area and various urban development parameters

    such as road density, population density, land use type

    and size of development units (Lo, 2001; Lo and Yang,

    2002; Weng, 2001; Cheng and Masser, 2003; Chabaeva

    et al., 2004,Sudhira et al., 2004). The convergence of

    GIS and database management systems has helped in

    quantifying, monitoring, modelling, and subsequently

    predicting the urban sprawl phenomenon. Characteris-

    ing urban sprawl pattern involves detection and

    quantification with appropriate scales and statisticalsummarization. Appropriate scale of urban sprawl

    characterization is the suitable spatial unit used in such

    analysis. Statistical summarization of urban growth

    pattern refers to representation of this phenomenon in

    terms of statistical parameters and indices like Shannon

    entropy, Patchiness, etc. Now, there are some metrics

    available to describe landscape pattern, quantify urban

    growth and its spatial distribution. The landscape

    pattern metrics are used for studying the forest patches

    (Trani and Giles, 1999; Civco et al., 2002) and detecting

    the urban sprawl pattern in village clusters (Sudhira

    et al., 2004). Most of the indices are correlated amongthemselves, because there are only a few primary

    measurements that can be made from patches (patch

    type, area, edge and neighbor type). All metrics are then

    derived from these primary measures. At the landscape

    level, GIS aids in calculating the landscape metrics, like

    patchiness and density in order to characterise land-

    scape properties in terms of spatial distribution and

    change (Trani and Giles, 1999; Yeh and Li, 2001; Civco

    et al., 2002,Sudhira et al., 2004). Such metrics have not

    been determined so far for most of the urban centres of

    India (Sudhira et al., 2004).

    M.K. Jat et al. / International Journal of Applied Earth Observation and Geoinformation xxx (2007) xxxxxx2

    + Models

    JAG-168; No of Pages 18

    Please cite this article in press as: Jat, M.K. et al., Monitoring and modelling of urban sprawl using remote sensing and GIS

    techniques, Int. J. Appl. Earth Observ. Geoinform. (2007), doi:10.1016/j.jag.2007.04.002

    http://dx.doi.org/10.1016/j.jag.2007.04.002http://dx.doi.org/10.1016/j.jag.2007.04.002
  • 8/12/2019 Grupo 1 Monitoring Urban Sprawl Using RS &Amp; GIS

    3/18

    Shannons entropy has been used in some of the

    studies to quantify the urban forms, such as impervious

    area in terms of spatial phenomenon (Yeh and Li, 2001;

    Sudhira et al., 2004; Joshi et al., 2006). Shannons

    entropy is based on the concept of information theory. It

    is a measure of uncertainty about the realisation of a

    random variable, like urban sprawl taking place in theform of impervious patches in newly developed areas. A

    quantitative measure is required to monitor and identify

    this fragmented urban sprawl. Developing this analogy,

    the mathematical representation of urban sprawl as a

    fragmented phenomenon and the concept of entropy are

    close (entropy is often used as a measure of dispersion

    of a random variable) (Joshi et al., 2006). Shannons

    entropy (Hn) is used to measure the degree of spatial

    concentration or dispersion of geophysical variable (Xi)

    among n spatial units/zones (wards). Entropy can be

    used to indicate the degree of urban sprawl/sprawl byexamining whether land development in a city is

    dispersed or compact (Lata et al., 2001; Sudhira et al.,

    2004; Joshi et al., 2006). Large value of Shannons

    entropy indicates dispersion of considered random

    variable (urban sprawl) which indicates occurrence of

    urban sprawl.

    Despite these efforts, further research is needed in

    order to reinforce absolute and comparative relationship

    between the magnitude of change in landscape

    imperviousness, type and intensity of urban land use/

    cover change and their causative factors.In India, currently 25.73% of the population (Census

    of India, 2001) is living in urban centers, while in the

    next 15 years it is projected to be around 33%. This

    indicates an alarming rate of urbanisation and possible

    urban growth that could take place. Measurement and

    modelling of urban sprawl using satellite images have

    not been well studied till date, especially in India

    (Sudhira et al., 2004).

    In this research, an attempt has been made to

    investigate the usefulness of the spatial techniques, like

    remote sensing and GIS for urban sprawl detection and

    handling of spatial and temporal variability of the same.Urban sprawl of Ajmer city (situated in Rajasthan State

    of India) in the last 25 years has been estimated using

    remote sensing images of eight different years ranging

    from 1977 to 2002. Remote sensing and GIS techniques

    have been used to extract the information related to

    urban sprawl. Spatial and temporal variation of urban

    sprawl is studied to establish a relationship between

    urban sprawl and some its causative factors, like

    population, population density, density of built-up.

    However, other relevant factors (e.g. socio-economic)

    are not considered in the present study due to non-

    availability of data. Statistical image classification

    approach, like maximum likelihood classifier (MLC)

    has been used for the analysis of satellite images

    obtained from various sensor systems. Classified

    images have been used to understand the dynamics

    of urban sprawl and to extract the area of impervious

    surfaces. In order to quantify the urban forms, such asimpervious area in terms of spatial phenomenon, the

    Shannons entropy (Yeh and Li, 2001) and the

    landscape metrics (patchiness, map density, etc.) are

    computed. The landscape metrics, normally used in

    ecological investigations, are being extended to

    enhance understanding of the urban forms. Computa-

    tion of these indices helped in understanding the process

    of urbanisation at a landscape level. Further, urban

    sprawl has been correlated with its causative factors,

    like population, population density, etc. using multi-

    variate regression analysis to arrive at a functionalrelationship. In addition to that, these relationships are

    used to predict the future urban sprawl.

    2. Study area

    The study area is located between 268200N to

    268350N latitudes and 748330E to 748450E longitudes

    (Fig. 1). Ajmer is situated 132 km from Jaipur, the

    capital of Rajasthan, India and flanked by Aravalli hills

    on two sides. Ajmer enjoys the status of being one of the

    major centres of higher learning and specializededucation in Rajasthan, apart from having historic

    importance. Administrative area of Ajmer spreads over

    an area of 250 km2. Population of Ajmer was

    0.49 million in the year 2001, and it is expected to

    be 0.84 million in 2034, as per the present growth rate.

    For a better planning of future urban development and

    infrastructure planning, municipal authorities need to

    know urban sprawl phenomenon of Ajmer, its

    distribution and in what way it is likely to move in

    the years to come.

    3. Data used

    The data has been collected from primary and

    secondary data sources (Table 1). The data collected

    from the primary sources include Survey of India (SOI)

    topo-sheets (scale, 1:25,000) (No. 45J/10/5, 6 and 45J/

    11/1, 2, 3, 4) and multi-spectral Landsat MSS, TM,

    ETM+ and Indian Remote Sensing (IRS) LISS-III

    images for the years 1977, 1989, 2000 and 2002. The

    data collected from secondary sources include the

    demographic data (primary census abstracts for the

    years 1961, 1971, 1981, 1991 and 2001) from the

    M.K. Jat et al. / International Journal of Applied Earth Observation and Geoinformation xxx (2007) xxxxxx 3

    + Models

    JAG-168; No of Pages 18

    Please cite this article in press as: Jat, M.K. et al., Monitoring and modelling of urban sprawl using remote sensing and GIS

    techniques, Int. J. Appl. Earth Observ. Geoinform. (2007), doi:10.1016/j.jag.2007.04.002

    http://dx.doi.org/10.1016/j.jag.2007.04.002http://dx.doi.org/10.1016/j.jag.2007.04.002
  • 8/12/2019 Grupo 1 Monitoring Urban Sprawl Using RS &Amp; GIS

    4/18

    Directorate of Census Operations, Census of India

    (Census of India, 1991; Census of India, 2001). Ward-

    wise population (year 2001) and urban settlement map

    of the Ajmer city (scale, 1:2500; year 2000) have been

    obtained from the Rajasthan Urban Infrastructure

    Development Projects (RUIDP) Ajmer. Other maps

    of Ajmer city, like ward map, municipal boundary map,drainage and master plan have been obtained from the

    Town Planning Department, Ajmer.

    4. Methodology

    Understanding the dynamic phenomenon, such as

    urban sprawl/growth, requires land use change ana-

    lyses, urban sprawl pattern identification and computa-

    tion of landscape metrics. ERDAS (Leica) and ArcGIS

    software (ESRI) have been used to generate various

    thematic layers, like ward map, Ajmer municipal

    boundary map, roads, railway network and adminis-

    trative boundary map using the topo-sheets and other

    available maps. Complete methodology has been

    presented inFig. 2.

    The standard image processing techniques, such as

    image extraction, rectification, restoration, and classi-

    fication have been used for the analysis of four satelliteimages (1977, 1989, 2000 and 2002). ERDAS imagine

    software has been used for image analysis. First of all,

    atmospheric correction has been applied using

    improved dark object subtraction method to bring all

    the images at common reference spectral character-

    istics. Water bodies available in the areas have been

    used as the dark object. Further, these subtracted images

    have been stretched to 8 bit digital number range.

    Images are further geo-referenced and geometrically

    corrected corresponding to the Polyconic projection

    system using the SOI topo-sheets.

    M.K. Jat et al. / International Journal of Applied Earth Observation and Geoinformation xxx (2007) xxxxxx4

    + Models

    JAG-168; No of Pages 18

    Please cite this article in press as: Jat, M.K. et al., Monitoring and modelling of urban sprawl using remote sensing and GIS

    techniques, Int. J. Appl. Earth Observ. Geoinform. (2007), doi:10.1016/j.jag.2007.04.002

    Fig. 1. Location of study area.

    Table 1

    Different type of data used

    S. no. Type of data used Scale/resolution Years

    1 Survey of India topo-sheets 1:25,000 1976 and 1977

    2 Landsat MSS image 57 m 1977

    3 Landsat TM image 28.5 m 1989

    4 Landsat ETM+ image 28.5 and 14.25 m 2000

    5 IRS 1D LISS-III image 23 m 2002

    6 Urban settlement map 1:2,500 20007 Municipal boundary map 1:25,000 2000

    8 Drainage map 1:2,500 2000

    9 Ward map and master plan 1:2,500 1988, 1991, 2000

    10 Census data Decadal 1961, 1971, 1981, 1991 and 2001

    http://dx.doi.org/10.1016/j.jag.2007.04.002http://dx.doi.org/10.1016/j.jag.2007.04.002
  • 8/12/2019 Grupo 1 Monitoring Urban Sprawl Using RS &Amp; GIS

    5/18

    Satellite images have been studied thoroughly to

    ascertain the probable land use classes and theirrespective range of reflectance values (DN values).

    Spectral profiles have been drawn to ascertain the

    seperability and relative difference in pixel values of

    different land use classes in different spectral bands.

    Ten separable land use classes have been identified,

    such as urban settlement, barren land, water, sandy soil,

    rocky terrain, exposed rocks, shrubs, mix vegetation,

    fallow land, etc. Initially, supervised classification using

    MLC algorithm has been performed for the classifica-

    tion of various images (Table 2). To enhance the

    classification accuracy, knowledge-based expert system

    was used for post-classification refinement of initially

    classified outputs.Initially, the algorithm was trained by supervised

    training process, after collection of parametric and non-

    parametric signatures (training samples). Each training

    sample consisted of at least 90 image pixels to satisfy

    the 10n criterion, wheren is the number of bands used

    for classification (Congalton, 1991). Signatures are

    further evaluated using three criterion to test whether

    they truly represent pixels to be classified for each class:

    (i) histogram plots to examine various statistical

    parameters, like standard deviation and uni-modality

    of the histogram, (ii) signatures separability using

    M.K. Jat et al. / International Journal of Applied Earth Observation and Geoinformation xxx (2007) xxxxxx 5

    + Models

    JAG-168; No of Pages 18

    Please cite this article in press as: Jat, M.K. et al., Monitoring and modelling of urban sprawl using remote sensing and GIS

    techniques, Int. J. Appl. Earth Observ. Geoinform. (2007), doi:10.1016/j.jag.2007.04.002

    Fig. 2. Flowchart of methodology.

    http://dx.doi.org/10.1016/j.jag.2007.04.002http://dx.doi.org/10.1016/j.jag.2007.04.002
  • 8/12/2019 Grupo 1 Monitoring Urban Sprawl Using RS &Amp; GIS

    6/18

    transformed divergence (TD), and (iii) contingency

    matrix, which contains the number and percentage of

    pixels which are classified as expected. Signatures are

    refined, deleted, renamed and merged after evaluation to

    ensure the uni-modality of their histograms, statistical

    parameters, contingency matrix and TD values. After

    evaluating the seperability, spectral band combination

    with good seperability (with highest TD value) havebeen selected for the final classification.

    Initially, hill shadow is classified as a separate class,

    however after field verification it has been merged with

    the shrub. Various manipulation techniques, like ratio,

    subtraction, etc., were tried initially to remove the hill

    shadow, but no significant improvement was observed.

    Classification results obtained from supervised classi-

    fication are not found satisfactory as misclassification

    has been observed for urban settlement (81.789.9%),

    exposed rocks (88.292%), and rocky terrain (75

    96.8%), which is substantiated from their lower overallaccuracy (81.784.7%).

    In second stage, knowledge-based expert system has

    been used for the post-classification refinement, i.e.

    rule-based system is applied on output from MLC in an

    attempt to modify and improve the classification.

    Ancillary information from various sources (DEM,

    municipal boundary map, location map of water bodies,

    soil map) has been integrated with outputs from MLC

    for the preparation of knowledge base (rule base). Rule

    base has further been refined from the ground truth data

    collection. Finally, classification has been done using

    the Knowledge Classifier Module of ERDAS. Classifiedresults of various images have been found satisfactory

    with higher overall accuracy of more than 94%, and

    presented inFig. 3. Further, classified images have been

    validated using the ground truth data and available maps

    from various agencies (RUIDP and Ajmer Town

    Planning Department).

    Classification accuracy of all the outputs has been

    assessed using a reference dataset of more than 300

    randomly selected pixels. Land use for these pixels have

    been determined using an urban settlement map

    (prepared from the aerial survey carried out in the year

    1999), and data collected from other maps (municipal

    boundary map, soil map, location map of water bodies,

    SOI topo-sheets and forest cover maps). The original

    satellite data has also been used for accuracy assessment

    to avoid errors in the reference dataset for temporally

    sensitive classes (such as vegetation). Urban settlement

    map of the city and geographical locations of some of

    important features, like type of vegetation at a particularlocation, important buildings, play grounds, water bodies

    and drains, collected during the field visits have also been

    used as ground truth data. Classification results of the

    older images (1977, 1989) have been done using the

    geographical locations of some of important features,

    like built-up area, type of vegetation at a particular

    location, important buildings, play grounds, water bodies

    and location of reserved forest patches etc available on

    SOI topo-sheets (printed in 1977) and town planning

    maps available. Further, accuracy report and Kappa

    Coefficient have been generated using the ERDASImagines accuracy assessment utility

    Urban sprawl/growth over a period of 25 years (1977

    2002) is obtained from the classified images and results

    are compared with settlement maps prepared by Ajmer

    Town Planning Department. To understand the urban

    sprawl pattern, different landscape metrics (Shannons

    entropy, Patchiness, and Map density) are calculated

    using the demographical and built-up area statistics.

    Population growth of the Ajmer city has been

    evaluated using the demographic data of four decades,

    i.e. 19612001 (Census of India). Decadal population

    growth trends are obtained by plotting the data andfitting the different type of distributions, like linear,

    logarithmic, exponential, power and polynomials.

    These distributions have been explored for the best

    form of relationship. Such a relationship could be used

    for population prediction. The distribution with highest

    correlation coefficient has been chosen for further use.

    Urban sprawl dynamics has been analysed considering

    some of the basic causative factors, like population (P),

    population density (PD), population density for the

    built-up (a density, aD) and population growth rate

    (PAGR). The rationale behind this is to identify such

    M.K. Jat et al. / International Journal of Applied Earth Observation and Geoinformation xxx (2007) xxxxxx6

    + Models

    JAG-168; No of Pages 18

    Please cite this article in press as: Jat, M.K. et al., Monitoring and modelling of urban sprawl using remote sensing and GIS

    techniques, Int. J. Appl. Earth Observ. Geoinform. (2007), doi:10.1016/j.jag.2007.04.002

    Table 2

    Transformed divergence (TD) for supervised classification of various images

    Year Sensor Spatial

    resolution (m)

    No. of spectral

    bands

    Spectral bands

    considered

    Transformed divergence (TD)

    Minimum Average

    1977 Landsat MSS 57 4 2, 3, 4 1802 1941

    1989 Landsat TM 28.5 7 1, 3, 4, 5 1748 19802000 Landsat ETM+ 28.5 and 14.5 6 1, 2, 4, 6 1997 2000

    2002 IRS 1D LISS-III 23 4 1, 3, 4 1993 2000

    http://dx.doi.org/10.1016/j.jag.2007.04.002http://dx.doi.org/10.1016/j.jag.2007.04.002
  • 8/12/2019 Grupo 1 Monitoring Urban Sprawl Using RS &Amp; GIS

    7/18

    factors that play a significant role in the process of

    urbanization. Multivariate regression analysis has been

    performed considering the urban sprawl in terms ofpercentage of impervious area (PB) as a dependent

    variable. Regression analysis has been performed for

    two cases considering the urban area (i) as a whole and

    (ii) at the ward level (for year 2000 only). Here ward

    refers to the spatial size of a developmental unit or zone,

    i.e. geographical area of a planning unit considered by

    the local development authorities for the landscape

    planning and administrative purposes. Percentage

    impervious area of a ward is the ratio of impervious

    to total area of ward (individual zone). The a population

    density for a ward is the ratio of the population in each

    ward to the impervious area of that ward. Thepopulation density for a ward is the ratio of population

    to the total area of ward. The population has been

    accepted as a key factor of urban sprawl. In the present

    study, PB, aD and PD are computed and analysed for

    the whole urban area (Case I) as well as ward-wise

    (categorised as a sub-zone) (Case II). The annual

    population growth rate (PAGR) parameter has been used

    only for Case I. Ward-wise analysis has been carried out

    for the year 2000 only, as ward-wise population data are

    not available for other years. Ward-wise impervious

    area has been obtained from the classified satellite

    image. ThePAGRfor the whole urban area is computed

    from the available population data (19612001).

    Population of in-between years has been obtained bypiecewise linear interpolation and fitted regression

    equation.

    In order to identify the probable relationship of PB

    (dependent variable) and individual causative factors,

    different distributions (linear, quadratic, exponential

    and logarithmic) have been explored for Case 1. The

    regression analyses reveal the individual contribution of

    causative factors on urban sprawl.

    To assess the cumulative effect of causative factors,

    stepwise multivariate regression analysis has been

    performed. In the multivariate regression, it is assumed

    that the relationship between variables is linear, which issupported by higher correlation coefficient for all

    individual causative factors. The multivariate regression

    gives the cumulative relationship between the variables.

    5. Results and discussion

    5.1. Image analysis

    Signature seperability results are presented (Table 2)

    in the form of TD values. Values of TD for different land

    use pairs lies within the satisfactory limits. Average

    M.K. Jat et al. / International Journal of Applied Earth Observation and Geoinformation xxx (2007) xxxxxx 7

    + Models

    JAG-168; No of Pages 18

    Please cite this article in press as: Jat, M.K. et al., Monitoring and modelling of urban sprawl using remote sensing and GIS

    techniques, Int. J. Appl. Earth Observ. Geoinform. (2007), doi:10.1016/j.jag.2007.04.002

    Fig. 3. Classified images of Ajmer fringe.

    http://dx.doi.org/10.1016/j.jag.2007.04.002http://dx.doi.org/10.1016/j.jag.2007.04.002
  • 8/12/2019 Grupo 1 Monitoring Urban Sprawl Using RS &Amp; GIS

    8/18

    value of TD for different images varies between 1941

    and 2000, which indicates good separation

    (TD> 1900). Minimum values of TD for different

    images lie between 1748 and 1993 (Table 1). Lower

    values of TD for some land use classes (1748) indicate

    that separation is fairly good. Best band combinations,corresponding to the highest values of TD have been

    selected for the supervised classification. From the two

    seperability evaluation criteria, it can be concluded that

    signatures are good enough for seperability. However,

    these signatures may represent a narrow range of

    reflectance values for each land use class, as these have

    been refined to satisfy various evaluation criterion.

    Seperability is slightly poor for the urban settlement as

    it is mixed with rocky terrain, exposed rocks and wet

    alluvium soil land use classes. This mixing of urban

    settlement and rocky land use classes is due toheterogeneous character (different type of construction

    material and different type of impervious surfaces) of

    urban area and surrounding hilly topography (exposed

    rocks and hills, where reflectance is similar to the built-

    up areas).

    For all images, results of accuracy assessment have

    been presented in Table 3. Results of the rule-based

    post-classification refinement have been found to be

    satisfactory with good overall accuracy. Both user and

    producer accuracies are almost same (Table 3) which

    further indicate consistent classification accuracy.

    Overall classification accuracy has been found to bemore than 90% for all the images (Table 3). Highest

    accuracy of 94.9% has been obtained for LISS-III image

    of the year 2002, while 94.0% accuracy has been

    obtained for the Landsat TM image of the year 1989.

    5.2. Population growth and built-up area

    Quadratic model has been found to be best fitted for

    the population growth of Ajmer city as compared to

    linear, exponential, logarithmic and power distribu-

    tions. Following quadratic relationship of population

    growth has been adopted for projection of population, as

    it has highest correlation coefficient (0.97) (Fig. 4).

    P 1:7556X2 55:087X168:220 (1)

    whereP is the population in thousand and Xis years in

    decade (1961 onwards). Lowest correlation has been

    found for the logarithmic distribution. Eq.(1)has been

    used for future population prediction. Values of the

    correlation coefficient for linear (0.96) and exponential

    (0.96) relationship are also not significantly different,

    which may be due to small number of data sets used to

    form the relationship.

    Urban sprawl for the years 1977, 1989, 2000 and

    2002 has been estimated in the form of impervious

    areas, which is obtained from the classified satelliteimages. Built-up area obtained from the classification

    may have some error due to mixed land use class pixels.

    Whether a particular pixel belongs to built-up or not,

    would depend upon the reflectance value from that

    pixel. MLC classification algorithm designates a

    particular pixel to a particular land use class, depending

    upon its reflectance characteristics (standard deviation

    and co-variance). In the present study, supervised

    classification has been used, which does not deal with

    sub pixel classification. However, results are further

    refined using knowledge-based approach by reducing

    the problem of mixed pixels. Urban area statistics forAjmer city is presented in Table 4 and Fig. 5.

    M.K. Jat et al. / International Journal of Applied Earth Observation and Geoinformation xxx (2007) xxxxxx8

    + Models

    JAG-168; No of Pages 18

    Please cite this article in press as: Jat, M.K. et al., Monitoring and modelling of urban sprawl using remote sensing and GIS

    techniques, Int. J. Appl. Earth Observ. Geoinform. (2007), doi:10.1016/j.jag.2007.04.002

    Table 3

    Overall accuracy of the image classification

    Year Classification accuracy

    Overall classification accuracy Overall kappa

    statisticsProducers

    accuracy (%)

    Users

    accuracy (%)1977 96.3 94.8 0.94

    1989 93.7 94.0 0.93

    2000 93.9 94.1 0.94

    2002 94.8 94.9 0.94

    Fig. 4. Population growth of Ajmer and best fit distributions.

    Table 4

    Urban growth statistics for the Ajmer city

    Year Built-up

    area (ha)

    Percentage

    increase in

    built-up area (%)

    Projected

    population

    Percentage

    growth in

    population (%)

    1977 488 331,073

    1989 838 71.7 397,279 19.9

    2000 1139 35.8 481,395 21.1

    2002 1259 10.5 497,160 3.27

    http://dx.doi.org/10.1016/j.jag.2007.04.002http://dx.doi.org/10.1016/j.jag.2007.04.002
  • 8/12/2019 Grupo 1 Monitoring Urban Sprawl Using RS &Amp; GIS

    9/18

    Impervious area (built-up) has increased from 488 ha in

    year 1977 to 1259 ha in year 2002. Results inTable 4

    reveal that the rate of land development in Ajmer hasoutstripped the rate of population growth. From the year

    1977 to 2002, population in the region grew by about

    50.2% while the amount of developed land grew by

    about 160.8%, i.e. more than three times the rate of

    population growth (Fig. 5 and Table 4). This implies

    that the land is being used for urbanization at a faster

    rate, which indicates that per capita consumption of

    land has increased exceptionally over last three decades.

    The per capita land consumption refers to utilisation of

    all lands for development initiatives, like commercial,

    industrial, educational, recreational and residentialestablishments per person.

    Spatial distribution of ward-wise urban sprawl in last

    25 years has been shown in Fig. 6. Urban sprawl is faster

    in outer area (ward number 16 and ward number 31

    55) along the major roads as compared to central

    portion of the city, which is also substantiated byFig. 6

    and landscape metrics. Here again, the hypothesis is

    correct that increase in economic conditions and

    development relates to urban sprawl (Census of India,

    2001).

    5.3. Metrics of urban sprawl

    5.3.1. Shannons entropy (Hn)

    In the present investigation, Shannons entropy (Hn)

    is used to measure the degree of spatial concentration or

    dispersion (homogeneity) of a geophysical variable

    (impervious area) among n spatial units/zones (wards).

    Shannons entropy (Yeh and Li, 2001) has been

    computed considering the urban sprawl in different

    wards to detect the form of urban sprawl phenomenon.

    Ward boundary map, obtained from the Municipal

    Corporation of Ajmer is taken as the base for theevaluation of the urban sprawl pattern from year 1977 to

    2002. Shannons entropy (Hn) is given by

    Hn X

    PilogePi (2)

    wherePiis the proportion of the variable in theith zone

    (ward), n is the total number of zones. Pi refers to the

    impervious areas inith wards,nrepresents total number

    of wards (55) and logn refers to the upper limit of

    entropy (1.7403). Shannons entropy has been calcu-

    lated across all the wards considering each ward as anindividual spatial unit.

    In the present study, impervious area (ward wise) has

    been considered as the geophysical variable, which

    enables determination of urban sprawl. Entropy may

    range from 0 to logn, indicating a compact distribution

    M.K. Jat et al. / International Journal of Applied Earth Observation and Geoinformation xxx (2007) xxxxxx 9

    + Models

    JAG-168; No of Pages 18

    Please cite this article in press as: Jat, M.K. et al., Monitoring and modelling of urban sprawl using remote sensing and GIS

    techniques, Int. J. Appl. Earth Observ. Geoinform. (2007), doi:10.1016/j.jag.2007.04.002

    Fig. 5. Growth of population and built-up area of Ajmer in last 25

    years.

    Fig. 6. Ward-wise urban growth of Ajmer from 1977 to 2002.

    http://dx.doi.org/10.1016/j.jag.2007.04.002http://dx.doi.org/10.1016/j.jag.2007.04.002
  • 8/12/2019 Grupo 1 Monitoring Urban Sprawl Using RS &Amp; GIS

    10/18

    of considered phenomenon (urbanisation) for values

    closer to zero and dispersed distribution for values

    closer to logn. Value of entropy near to log nreveal the

    dispersion of the geophysical variable (impervious

    area), which indicates occurrence of urban sprawl.

    Shannons entropy results for 4 years (1977, 1989, 2000

    and 2002) have been presented in Table 5. Entropy

    values have been calculated across all wards, and are

    summed-up to represent the entropy for the whole urban

    area. Larger value of entropy, more than 1.6 (Table 5)reveals the occurrence and spatial distribution of the

    variable (urban sprawl). Ward-wise results have not

    been presented due to their large number (55 wards).

    Relatively lower value of Shannons entropy (1.54) in

    the year 1977 indicates the compact and homogeneous

    distribution of the impervious area (built-up). Fig. 3

    reveals that urban area was more compact in year 1977.

    Dispersed distribution of the impervious area has been

    observed in recent years (Fig. 3), which is also revealed

    by the results of Shannons entropy. Entropy value has

    increased from 1.54 in year 1977 to 1.60 in year 1989.Further, value of Shannons entropy has increased from

    1.60 in year 1989 to 1.62 in year 2000. This increase in

    value of entropy indicates increase in dispersion of

    impervious area, which reveals urban sprawl. The

    entropy values obtained are 1.54 in 1977, 1.60 in 1989,

    1.62 in 2000 and 1.62 in 2002. These are closer to the

    upper limit of log n, i.e. 1.74, showing the degree of

    dispersion of built-up in the region. Higher value of

    overall entropy for the whole urban area represents

    higher dispersion of impervious area, which is a sign of

    urban sprawl. Increase in dispersion is due to new areas

    being added to the municipal boundaries and some ofthe new housing schemes implemented by the Govern-

    ment. The degree of dispersion has reduced marginally

    from year 2000 to 2002, which indicates an increase in

    homogeneity of impervious area. Ward-wise imper-

    vious area in different years (Fig. 6) further substantiate

    the entropy results. Value of entropy has increased

    gradually from 0.15 (1977) to 0.57 (2002) for the wards

    located along the major roads, like ward number 14,

    10, 11, 35, 36, 39, 40 and 5355. The higher values of

    entropy in outer areas indicate more urban sprawl as

    compared to central Ajmer, indicating more dispersion

    of impervious areas in outer wards. Distribution is

    predominantly dispersed in outer areas, whereas it is

    compact in areas surrounding central Ajmer. Hence, it

    can be concluded that Shannons entropy is useful and

    effective in identifying the urban sprawl phenomenon in

    terms of dispersion of the impervious area.

    5.3.2. Patchiness

    Patchiness or landscape diversity is the number of

    different land use classes within then nwindow. It isa measure of diversity of all land use class patches. In

    other words, it is a measure of number of heterogeneous

    land use/cover polygons over a particular area. Greater

    the patchiness, more is the heterogeneous landscape. In

    this study, number of patches of different land use

    categories has been computed by moving a 55 sizekernel on the classified image using model maker utility

    of the ERDAS Imagine software. Size of kernel hasbeen chosen as per the number of land use categories

    available in a particular image. There are 10 land use

    categories available in most of the classified images,

    which is more than the number of pixels in a 33 sizekernel. Therefore, kernel of 55 size has been used inthe present study. Land use diversity in terms of

    patchiness has been determined using the respective

    classified images for year 1977, 1989, 2000 and 2002.

    Ward-wise landscape diversity and its percentage

    distribution for the different years have been presented

    in Fig. 7 and Table 6. Results reveal that diversity rangesfrom 1 to 7 land use class categories. One land use class

    category represents that only one land use class is

    available within the kernel, two land use class category

    represent that any two land use classes are available

    within the kernel, corresponding to central pixel of the

    kernel. For all the years, one and two heterogeneous

    land use classes categories are highest, whereas five to

    seven heterogeneous class categories have been found

    to be minimum (Table 6). However, one land use class

    category has gradually increased from 36.6% in year

    1977 to 62.4% in year 2002 and two land use class

    category has reduced from 50.8% in year 1977 to 32.3%in year 2002. Category fourth has increased from 0.76%

    in year 1977 to 8.3% in year 2000, which indicates

    continuous process of urbanisation in new areas.

    Landscape diversity is more in the year 2000 as

    compared to 2002. This reveals that the percentage of

    homogeneous area has increased gradually since 1977,

    while the remaining area which is heterogeneous with

    patch class ranging from two to six has reduced. Change

    in the values of patchiness with time represents the

    change in land use heterogeneity, like diversity of one

    land use category has increased from, 36.6% to 62.4%.

    M.K. Jat et al. / International Journal of Applied Earth Observation and Geoinformation xxx (2007) xxxxxx10

    + Models

    JAG-168; No of Pages 18

    Please cite this article in press as: Jat, M.K. et al., Monitoring and modelling of urban sprawl using remote sensing and GIS

    techniques, Int. J. Appl. Earth Observ. Geoinform. (2007), doi:10.1016/j.jag.2007.04.002

    Table 5

    Shannons entropy for the study area

    Year Shannons entropy

    1977 1.54

    1989 1.60

    2000 1.62

    2002 1.61

    http://dx.doi.org/10.1016/j.jag.2007.04.002http://dx.doi.org/10.1016/j.jag.2007.04.002
  • 8/12/2019 Grupo 1 Monitoring Urban Sprawl Using RS &Amp; GIS

    11/18

    This indicates that diversity of one type of land use

    category has increased, which means other land use

    categories have been changed into this category. Results

    of the diversity analysis are well in agreement with the

    Shannons entropy results.

    5.3.3. Map density

    Map density is another index which can be used to

    examine the homogeneity/dispersion of any spatial

    phenomenon, like urbanisation. Distribution of imper-

    vious areas, which indicates urban sprawl, has been

    studied using density metrics. Map density values are

    computed by determining the number of impervious

    area pixels out of the total number of pixels in a 55kernel. Here again size of kernel has been chosen as per

    the maximum number of land use categories available

    in a particular image. There are 10 land use categories

    available in most of the classified images, which is more

    M.K. Jat et al. / International Journal of Applied Earth Observation and Geoinformation xxx (2007) xxxxxx 11

    + Models

    JAG-168; No of Pages 18

    Please cite this article in press as: Jat, M.K. et al., Monitoring and modelling of urban sprawl using remote sensing and GIS

    techniques, Int. J. Appl. Earth Observ. Geoinform. (2007), doi:10.1016/j.jag.2007.04.002

    Fig. 7. Diversity of land use classes (patchiness).

    http://dx.doi.org/10.1016/j.jag.2007.04.002http://dx.doi.org/10.1016/j.jag.2007.04.002
  • 8/12/2019 Grupo 1 Monitoring Urban Sprawl Using RS &Amp; GIS

    12/18

    than the number of pixels in a 33 size kernel.Therefore, kernel of 55 size has been used in thepresent study. When this is applied to a classified

    satellite image, it converts land use classes into 25density classes. For example, density value of 5 for a

    pixel represents 5 impervious area pixels in a 55kernel. Depending on the density levels, it is further

    classified into five categories using the equal interval

    method as very low, low, medium, high and very high-

    density classes, corresponding to the density value

    (number of built-up pixels out of 25 pixels) of 5, 10, 15,

    20 and more than 20. Density landscape metrics have

    been computed for all the 4 years (1977, 1989, 2000 and

    2002). Further relative percentage of each density

    category (percentage of total impervious area in aparticular category) has been computed for each year,

    which enabled identification of different urban sprawl

    centers. Subsequently results have been correlated with

    the Shannons entropy.

    Results of the built-up/impervious area density

    metrics have been presented in Fig. 8. Re-classified

    categories of the densities (in terms of percentage of the

    total impervious area) have been presented inTable 7.

    Very high and high density of built-up area would refer to

    cluster or more compact nature of the built-up theme.

    While medium density would refer to relatively lesser

    compact built-up and low and very low density refer toloosely or sparsely spread built-up areas. The percentage

    of high-density (built-up area) has gradually increased

    from 19.5% in 1977 to 23.1% in 2002. The percentage of

    very high-densitybuilt-up area is more than 43.7% till the

    year 1989, however it has reduced afterward (Table 7).

    This revealed that percentage of compact or highly dense

    built-up area has reduced on account of development of

    new areas, which indicates dispersion. This reduction

    does not mean that impervious areas have decreased

    since 1989. Relative share of very high compact built-up

    area has been reduced, though total area under this

    category has not reduced. In the year 1989, area under

    very high density was 366 ha, which has increased to

    372 ha in year 2002. However, its percentage with respect

    to the total area under all categories has been reduced.Increase in the value of very low, low, medium and high-

    density categories reveal urban sprawl and new devel-

    opmental activities. Fig. 8 reveals that more land

    development have taken place in outer areas (ward

    number 1, 2, 3, 4, 5, 35, 39, 40, 53, 54 and 55), along the

    major roads and railway line. An important inference

    could be drawn here that high and medium density is

    found all along the main roads (National Highway),

    railway station and the city center (near railway station

    and Anasagar lake area). Most of the high density is

    found within the central portion of the city. Mediumdensity is found along the city periphery and on the

    highways. Increase in impervious surfaces (from 1977 to

    2002) in outer areas (ward number 15, 35, 39, 40, 53, 54

    and 55) substantiate the results of density metrics.

    Further, density results substantiate the results of

    Shannons entropy, which reveal an urban sprawl in

    outer areas. Hence, these metrics are effective in

    determination of urban sprawl and its spatial distribution.

    5.4. Dynamics of urban sprawl

    Defining the dynamic urban sprawl phenomenon andits future prediction is a greater challenge than its

    quantification. Although different sprawl types are

    identified and defined, there has been an inadequacy

    with respect to developing mathematical relationships

    to define them. This necessitates the characterization

    and modelling of urban sprawl, which may aid in

    regional planning, planning and development of water

    resources and designing of urban drainage infrastruc-

    ture. In the present investigation, population and related

    densities are used as independent variables for

    modelling the urban sprawl.

    M.K. Jat et al. / International Journal of Applied Earth Observation and Geoinformation xxx (2007) xxxxxx12

    + Models

    JAG-168; No of Pages 18

    Please cite this article in press as: Jat, M.K. et al., Monitoring and modelling of urban sprawl using remote sensing and GIS

    techniques, Int. J. Appl. Earth Observ. Geoinform. (2007), doi:10.1016/j.jag.2007.04.002

    Table 6

    Percentage distribution of patchiness for the Ajmer municipal area

    No. of diversity

    class

    Percentage

    distribution (1977)

    Percentage

    distribution (1989)

    Percentage

    distribution (2000)

    Percentage

    distribution (2002)

    1 36.6 31.2 53.1 62.4

    2 50.8 46.7 23.3 32.3

    3 11.7 18.6 14.9 4.94 0.76 3.06 8.3 0.2

    5 0.009 0.21 0.11 0.003

    6 0.00 0.005 0.10 0.001

    7 0.0 0.0 0.005 0.0

    While deriving diversity of different land use classes within municipal boundary of the Ajmer, diversity function of the ERDAS Focal (Scan) model

    has been used considering 55 size of kernel window.

    http://dx.doi.org/10.1016/j.jag.2007.04.002http://dx.doi.org/10.1016/j.jag.2007.04.002
  • 8/12/2019 Grupo 1 Monitoring Urban Sprawl Using RS &Amp; GIS

    13/18

    5.5. Modelling of urban sprawl

    Initially, analysis has been performed considering

    the individual causative factor (independent variables)

    to ascertain their significance (form of equation) on the

    urban sprawl. The regression analyses reveal the

    individual contribution of causative factors on urban

    sprawl. Various relationships and their statistical

    parameters have been presented inTable 8.

    Relationships between PB andP have been found to

    be quadratic with lowest standard error of estimate

    (S.E. = 0.06) and higher correlation coefficient (0.988).

    Relationships between PB and PD have been found to

    be linear. Linear regression results shows highest

    correlation coefficient (0.995) and lowest standard

    error of estimate (S.E. = 0.507) for PD. Relationships

    between PB and have been also found to be quadratic

    with highest correlation coefficient (0.99) and lowest

    M.K. Jat et al. / International Journal of Applied Earth Observation and Geoinformation xxx (2007) xxxxxx 13

    + Models

    JAG-168; No of Pages 18

    Please cite this article in press as: Jat, M.K. et al., Monitoring and modelling of urban sprawl using remote sensing and GIS

    techniques, Int. J. Appl. Earth Observ. Geoinform. (2007), doi:10.1016/j.jag.2007.04.002

    Fig. 8. Urban sprawl densities.

    http://dx.doi.org/10.1016/j.jag.2007.04.002http://dx.doi.org/10.1016/j.jag.2007.04.002
  • 8/12/2019 Grupo 1 Monitoring Urban Sprawl Using RS &Amp; GIS

    14/18

    standard error of estimate (S.E. = 0.48). Relationships

    between PB and PAGRhave been found to be quadraticwith highest correlation coefficient (0.85) and lowest

    standard error of estimate (S.E. = 2.12). The linear and

    quadratic regression analyses reveal that the population

    and population density have significant influence on PB.

    Quadratic relationship is prominent for the P, aD andPAGR, however linear relationship can be adopted for

    multivariate analysis as the coefficient of quadratic

    terms are very small. The quadratic regression analyses

    M.K. Jat et al. / International Journal of Applied Earth Observation and Geoinformation xxx (2007) xxxxxx14

    + Models

    JAG-168; No of Pages 18

    Please cite this article in press as: Jat, M.K. et al., Monitoring and modelling of urban sprawl using remote sensing and GIS

    techniques, Int. J. Appl. Earth Observ. Geoinform. (2007), doi:10.1016/j.jag.2007.04.002

    Table 7

    Different densities of built-up and their percentage area

    Category Diversity in year 1977 Diversity in year 1989 Diversity in year 2000 Diversity in year 2002

    Percentage of

    total impervious

    area (%)

    Area

    (ha)

    Percentage of

    total impervious

    area (%)

    Area

    (ha)

    Percentage of

    total impervious

    area (%)

    Area

    (ha)

    Percentage of

    total impervious

    area (%)

    Area

    (ha)

    Very low density 0.4 2 1.03 8.6 7.78 88 7.95 104

    Low density 5 26 15.08 126 17.16 195 17.18 221

    Medium density 17 84 20.3 170 19.81 225 22.72 292

    High density 19 95 19.89 166 22.89 260 23.11 297

    Very high density 57 280 43.7 366 32.36 368 29.55 372

    Very low density (15 pixels of built-up), low density (610 pixels of built-up), medium density (1115 pixels of built-up), high density (1620

    pixels of built-up), very high density (2125 pixels of built-up) (out of 25 pixels). Built-up densities have been obtained using a 5 5 size of kernel.25 density classes have been obtained. Further density output classified into five classes as mentioned above.

    Table 8

    Coefficients of casual factors and percentage built-up using regression analysis

    Dependent variable (y) Independent

    variable (x)

    Equation

    (y= mx + c)

    S.E. of

    y estimate

    Correlation

    coefficient,R

    Linear regression

    PB P PB = 5.412P11.84 0.507 0.99

    PB PD PB = 0.4607PD11.84 0.507 0.99PB aD PB =0.0327aD + 26.846 1.393 0.96PB PAGR PB = 5.412PAGR11.84 3.679 0.68

    Dependent variable (y) Independent

    variable (x)

    Equation

    (y= mlnx + c)

    S.E. of

    y estimate

    Correlation

    coefficient,R

    Logarithmic

    PB P PB = 22.8 ln(P)284.95 0.59 0.98PB PD PB = 22.86 ln(PD)78.027 0.59 0.98PB aD PB =17.436 ln(aD) + 118.359 1.13 0.95PB PAGR PB =1.61 ln(PAGR) + 24.33 3.43 0.38

    Dependent variable (y) Independent

    variable (x)

    Equation

    (y= ax2 +bx +c)

    S.E. of

    y estimate

    Correlation

    coefficient,R

    Polynomial 2nd order

    PB P PB =6.3E12P2 + 5.96E05P12.98 0.06 0.98PB PD PB =4.5E4PD2 + 0.506P12.98 0.6 0.98PB aD PB = 1.48E04aD2 1905aD + 66.585 0.48 0.99PB PAGR PB =6.3E07P2AGR + 3.35E03PAGR+ 9.705 2.1 0.85

    Dependent variable (y) Independent

    variable (x)

    Equation

    (y= mxz)

    S.E. of

    y estimate

    Correlation

    coefficient,R

    Power

    PB P PB = 5.12E12P2.192 0.029 0.98PB PD PB = 2.05E3PD2.192 0.029 0.98PB aD PB = 4.78E+05aD1.744 0.02 0.988

    PB PAGR PB = 46.64P0:182

    AGR

    0.13 0.45

    http://dx.doi.org/10.1016/j.jag.2007.04.002http://dx.doi.org/10.1016/j.jag.2007.04.002
  • 8/12/2019 Grupo 1 Monitoring Urban Sprawl Using RS &Amp; GIS

    15/18

    revealed that aD and PAGRhave a considerable role in

    the urban sprawl phenomenon. The power law

    regression analyses reveal that the population density

    has influenced the urban sprawl phenomenon, which is

    evident from the value of exponent. Annual population

    growth shows positive correlation with percentage

    built-up, which is again a population-derived parameter.

    In multivariate regression, it is assumed that therelationship between variables is linear as the coeffi-

    cient of quadratic terms is very small and same is

    supported by the higher correlation coefficient for linear

    and quadratic relations (Table 9). The multivariate

    regression gives the cumulative relationship among the

    independent and dependent variables. Details of the

    multivariate regression analysis have been presented in

    Table 9. Following relationship have been found to be

    most suitable for both the Cases (I and II).

    Case I: whole area

    PB 0:3564 PD0:00688aD3:504

    R 0:998;F 2:62E5; S:E: 0:49 (3)

    PB 3:1E05P 0:6854PD

    8:4E05PGR9:610 R 0:99 (4)

    Case II: at ward level

    PB 0:00395P 0:09524PD

    0:01144aD 59:058

    R

    0:87;F

    2:25E15; S:E: 16:6 (5)

    Considering all the causative factors in the stepwise

    regression, Eq.(3) for Case I and Eq. (5)for Case II

    have been found to be best fit with highest correlation

    coefficient, lowest standard error of estimate and lowest

    significance F. In Case I, it is to be noted that correlation

    coefficient is same for relationships (Eq.(4)) with other

    parameters, however relationship of PB with PD andaD

    is found most suitable as its significanceF is smallest.Significance Fis a statistical criterion which indicates

    degree of relationship. Smaller value of significance F

    indicates good relationship. Eqs. (3)(5) confirm that

    the causative factors collectively have a significant role

    in the urban sprawl phenomenon, which can be

    understood from the satisfactory positive correlation

    coefficients.

    M.K. Jat et al. / International Journal of Applied Earth Observation and Geoinformation xxx (2007) xxxxxx 15

    + Models

    JAG-168; No of Pages 18

    Please cite this article in press as: Jat, M.K. et al., Monitoring and modelling of urban sprawl using remote sensing and GIS

    techniques, Int. J. Appl. Earth Observ. Geoinform. (2007), doi:10.1016/j.jag.2007.04.002

    Table 9

    Coefficient of casual factors and percentage built-up by multivariate linear regression analyses

    Dependent variable Independent

    variable

    Equation Standard error

    of estimate

    Correlation

    coefficient

    Case I: whole urban area

    Percentage built-up (PB) P and PD PB =3.1105P+ 0.708PD11.5 0.71 0.99

    Percentage built-up (PB) PD and aD PB = 0.3564PD0.00688aD3.504 0.48 0.99Percentage built-up (PB) P and aD PB = 4.19105P0.00688aD3.504 0.48 0.98Percentage built-up (PB) P, PD and aD PB =3.1105P+ 0.616PD0.00688aD3.504 0.6 0.98Percentage built-up (PB) PD, aD and PGR PB = 0.00285PD0.0447aD + 0.000567PGR + 27.797 0.0 0.98Percentage built-up (PB) P, PD and PGR PB =3.1E05P+ 0.6854PD8.4E05PGR9.610 0 0.99

    Case II: ward wise for the year 2000

    Percentage built-up (PB) P PB = 0.0057P+ 82.42 27.7 0.53Percentage built-up (PB) PD PB = 0.092PD + 17.186 24.9 0.65

    Percentage built-up (PB) aD PB =0.00752aD + 41.953 31.3 0.28Percentage built-up (PB) P and PD PB =0.00437P+ 0.0.07933 PD55.785 21.4 0.76Percentage built-up (PB) PD and aD PB = 0.10782PD0.01234aD + 24.798 20.2 0.79Percentage built-up (PB) aD and P PB = 0.00704aD0.0056P+ 87.73 26.6 0.59Percentage built-up (PB) P, PD and aD PB =0.00395P+ 0.09524PD0.01144aD + 59.058 16.6 0.87

    Here,B is built-up area in ha, PB is percentage built-up area; P is population; PD is population density (person/ha), and aD is the alpha density

    (proportion of population to built-up area in each ward).

    Fig. 9. Prediction of urban growth for Ajmer.

    http://dx.doi.org/10.1016/j.jag.2007.04.002http://dx.doi.org/10.1016/j.jag.2007.04.002
  • 8/12/2019 Grupo 1 Monitoring Urban Sprawl Using RS &Amp; GIS

    16/18

    5.6. Predicting scenarios of urban sprawl

    Urban sprawl of Ajmer has been predicted using

    Case I relationship, as ward-wise population is available

    only for year 2000. Likely increase in the impervious

    area (built-up) is predicted using Eq.(4)as population,

    population density and annual population growth rateare available from the historical data. To project the

    impervious area (built-up) from year 2011 to 2041

    (decadal growth) within the notified municipal area,

    corresponding population has been computed using

    Eq.(1). It is estimated that the percentage built-up for

    2011 and 2051 would be 17.9% and 33.9%, respectively

    (Fig. 9). This implies that by year 2051, the built-up area

    in the municipal limits would rise to 2889 ha, which

    may be nearly 129.3% more than the built-up (1259 ha)

    in year 2002. Thus, the pressure on land would further

    grow and the vegetal areas, open grounds and regionaround the highways are likely to become prime targets

    for urban sprawl.

    Remote sensing technology is indispensable for

    dealing with dynamic phenomenon, like urban sprawl.

    Without remote sensing data, one may not be able to

    monitor and estimate the urban sprawl effectively over a

    time period, especially for elapsed time period. This

    technology is cost effective in dealing with phenom-

    enon like urban sprawl, as other conventional data

    collection and surveying techniques are found to be

    time consuming and expensive. Spatial and temporalvariability of land use/cover change can be monitored

    using remote sensing data. In the present study, ward

    wise built-up areas have been determined over a period

    of 25 years, which would not have been possible

    without the use of remote sensing data. Landscape

    metrics have been computed using satellite images to

    understand the form and spatial distribution of urban

    sprawl. Such metrics cannot be obtained from the maps

    prepared using other techniques.

    In the present investigation, population and related

    densities are used as independent variables for

    modelling the urban sprawl as data were available onlyfor these parameters. Many other parameters, like

    socio-economic conditions, governmental investments

    for public sector works, scope of industrialization,

    tourist activities and distance from important places like

    railway station can also be considered in urban sprawl

    modelling. Many other physical barriers are not

    considered in the present investigation which may

    influence the urban sprawl phenomenon, like hilly range

    available in west and north side of the study area.

    However, availability of such detailed data is a difficult

    task in developing countries like India.

    Other physical and topographical features, like hilly

    barriers, rocky areas, etc. along with other causative

    factors (as mentioned above) can be considered in the

    future urban sprawl modelling studies.

    Ward level scale is more suitable for urban sprawl

    studies as it represents the actual spatial diversity of

    built-up phenomena within the city. In the present studyurban sprawl phenomenon has been studied at ward

    level to show the dynamic pattern of urban sprawl and

    its spatial distribution or the changes in urbanization.

    Use of landscape metrics has been extended to study the

    urban sprawl, as a spatial phenomenon within the

    different spatial units or administrative zones of an

    urban centre. Ward level analysis has been performed

    for 1 year as data were not available for other years.

    However, developed relationships can be refined using

    the data of more number of years in future research

    work.

    6. Conclusion

    The urban sprawl is seen as one of the potential

    challenge to sustainable development where urban

    planning with effective resource utilization, allocation

    of natural resources and infrastructure initiatives are key

    concerns. The study has attempted to understand the

    urban sprawl of Ajmer city, quantified by defining

    important metrics (Shannon entropy, Patchiness and

    Density) and modelling the same for future prediction.Remote sensing and GIS techniques have been used to

    demonstrate their application for the monitoring and

    modelling of dynamic phenomena, like urbanisation.

    The spatial and attribute data of the region have been

    aided in statistical analysis and defining few of the

    landscape metrics.

    Shannons entropy, Patchiness and built-up density

    landscape metrics have been computed which helped in

    understanding the form of urban sprawl and its spatial

    pattern. Larger value of entropy (near to upper limit)

    reveals the occurrence and spatial distribution of the

    urban sprawl. Results of the diversity analysis are wellin agreement with the Shannons entropy. Urban sprawl

    is taking place continuously at a faster rate in outer

    areas, bringing more area under built-up category as

    revealed by metrics (dispersed growth). Built-up

    density results substantiate the results of Shannons

    entropy, which reveal an urban sprawl in outer areas.

    Landscape metrics have been found to be effective in

    determination of urban sprawl and its spatial distribu-

    tion. Multivariate regression analysis has been per-

    formed to develop a relationship between urban sprawl

    and some of its causative factors. It has been found that

    M.K. Jat et al. / International Journal of Applied Earth Observation and Geoinformation xxx (2007) xxxxxx16

    + Models

    JAG-168; No of Pages 18

    Please cite this article in press as: Jat, M.K. et al., Monitoring and modelling of urban sprawl using remote sensing and GIS

    techniques, Int. J. Appl. Earth Observ. Geoinform. (2007), doi:10.1016/j.jag.2007.04.002

    http://dx.doi.org/10.1016/j.jag.2007.04.002http://dx.doi.org/10.1016/j.jag.2007.04.002
  • 8/12/2019 Grupo 1 Monitoring Urban Sprawl Using RS &Amp; GIS

    17/18

    the change in built-up over the period of nearly 25 years

    is 160.8% and by year 2051, the built-up area in the

    region would rise to 2889 ha, which would be nearly

    129.3% more than the sprawl of 1259 ha in year 2002.

    Rate of urban sprawl would be about two times the

    population growth, if projected using the present trend.

    Further, other causative factors, like socio-economicconditions, governmental investments for public sector

    works, scope of industrialization, tourist activities,

    physical barriers and distances from important locations

    can also be considered for urban growth modelling in

    future research work.

    These metrics and relationship between urban sprawl

    and some its causative factors are useful for the local

    development authorities and municipalities to deter-

    mine spatial distribution of sprawl. Also such relation-

    ships can be used to predict and quantify urban sprawl,

    which can be used for optimal planning of land andnatural resources, zonal and regional planning and

    designing of urban drainage infrastructure. Remote

    sensing technology is indispensable for dealing

    dynamic phenomenon, like urban sprawl. Without

    remote sensing data, one may not be able to monitor and

    estimate the urban sprawl effectively over a time period,

    especially for elapsed time period.

    Acknowledgements

    The first author greatly acknowledges the RajasthanUrban Infrastructure Project Authorities, PHED Ajmer,

    and Town Planning Department of the Government of

    Rajasthan for providing data used in this work, and

    AICTE and QIP Centre of IIT Roorkee for providing

    financial support for this work. The first author

    acknowledges Mr. Rohit Bhakar for helping in

    improving the English of this manuscript. Authors

    sincerely thank all Referees for their suggestions to

    improve the manuscript.

    References

    Barnes, K.B., Morgan III, J.M., Roberge, M.C., Lowe, S., 2001.

    Sprawl development: its patterns, consequences, and measure-

    ment. Towson University, Towson. http://www.chesapeake.towso-

    n.edu/landscape/urbansprawl/download/Sprawl.white paper.pdf.

    Batty, M., Xie, Y., Sun, Z., 1999. The dynamics of urban sprawl.

    Working Paper Series, Paper 15, Centre for Advanced Spatial

    Analysis, University College, London.

    Census of India, 1991. http://www.censusindia.net.

    Census of India, 2001. http://www.censusindia.net.

    Chabaeva, A.A., Civco, D.L., Prisloe, S., 2004. Development of a

    population density regression model to calculate imperviousness.

    In: ASPRS Annual Conference Proceedings, Denver, CO, USA.

    Cheng, J., Masser, I., 2003. Urban growth pattern modelling: a case

    study of Wuhan City, PR China. Landsc. Urban Plan 62, 199

    217.

    Civco, D.L., Hurd, J.D., Wilson, E.H., Arnold, C.L., Prisloe, M.,

    2002. Quantifying and describing urbanizing landscapes in the

    Northeast United States. Photogr. Eng. Remote Sens. 68 (10),

    10831090.

    Congalton, R.G., 1991. A review of assessing the accuracy of classi-fication of remote sensing data. Remote Sens. Environ. 37, 3546.

    Epstein, J., Payne, K., Kramer, E., 2002. Techniques for mapping

    suburban sprawl. Photogr. Eng. Remote Sens. 63 (9), 913918.

    Gomarasca, M.A., Brivio, P.A., Pagnoni, F., Galli, A., 1993. One

    century of land use changes in the metropolitan area of Milan

    (Italy). Int. J. Remote Sens. 14 (2), 211223.

    Gordon, N.D., McMahon, T.A., Finlayson, B.L., 1992. Stream

    Hydrology: An Introduction for Ecologists. John Wiley & Sons

    Ltd., Baffins Lane, Chichester, West Sussex, England.

    Green, K., Kempka, D., Lackey, L., 1994. Using remote sensing to

    detect and monitor land-cover and land-use change. Photogr. Eng.

    Remote Sens. 60, 331337.

    Greenberg, J.D., Bradley, G.A., 1997. Analyzing the urbanwildland

    interface with GIS. J. Forestry 95, 1822.

    Haack,B.N.,Rafter, A.,2006.Urban growthanalysisand modellingin

    the Kathmandu valley, Nepal. Habitat International 30 (4), 1056

    1065.

    Hurd, J.D., Wilson, E.H., Lammey, S.G., Civco, D.L., 2001. Char-

    acterisation of forest fragmentation and urban sprawl using time

    sequential Landsat Imagery. In: Proceedings of the ASPRS

    Annual Convention, St. Louis, MO, April 2327, p. 2001.

    Jantz, C.A., Goetz, Scott, J., 2005. Analysis of scale dependencies in

    an urban land-use-change model. Int. J. Geogr. Inform. Sci. 19 (2),

    217241.

    Jat, M.K., Garg, P.K., Khare, D., 2006. Assessment of urban growth

    pattern using spatial analysis techniques. In: Proceedings of Indo-

    Australian Conference on Information Technology in Civil Engi-neering (IAC-ITCE), February 2021, p. 70.

    Joshi, P.K., Lele, N., Agarwal, S.P., 2006. Entropy as an indicator of

    fragmented landscape. Curr. Sci. 91 (3), 276278.

    Lata, K.M., Sankar Rao, C.H., Krishna Prasad, V., Badrinath, K.V.S.,

    Raghavaswamy, 2001. Measuring urban sprawl: a case study of

    Hyderabad. GIS Dev. 5 (12).

    Li, G., Weng, Q., 2005. Using Landsat ETM+ imagery to measure

    population density in Indianapolis, Indiana, USA. Photogr. Eng.

    Remote Sens. 71 (8), 947958.

    Lo, C.P., Yang, X., 2002. Drivers of land-use/land-cover changes and

    dynamic modelling for the Atlanta, Georgia Metropolitan Area.

    Photogr. Eng. Remote Sens. 68 (10), 10621073.

    Lo, C.P., 2001. Modeling the population of China using DMSP

    operational Linescan system nighttime data. Photogr. Eng.Remote Sens. 67, 10371047.

    Lu, D., Weng, Q., 2005. Urban classification using full spectral

    information of Landsat ETM+ imagery in Marion County, Indiana.

    Photogr. Eng. Remote Sens. 71 (11), 12751284.

    Mundia, C.N., Aniya, M., 2005. Analysis of land use/cover changes

    andurban expansion of Nairobi city using remotesensing andGIS.

    Int. J. Remote Sens. 26 (13), 28312849.

    Paul, M.J., Meyer, J.L., 2001. Streams in the urban landscape. Ann.

    Rev. Ecol. Syst. 32, 333365.

    Stefanov, W.L., Ramsey, M.S., Christensen, 2001. Monitoring urban

    land cover change: an expert system approach to land cover

    classification of semiarid to arid urban centers. Remote Sens.

    Environ. 77, 173185.

    M.K. Jat et al. / International Journal of Applied Earth Observation and Geoinformation xxx (2007) xxxxxx 17

    + Models

    JAG-168; No of Pages 18

    Please cite this article in press as: Jat, M.K. et al., Monitoring and modelling of urban sprawl using remote sensing and GIS

    techniques, Int. J. Appl. Earth Observ. Geoinform. (2007), doi:10.1016/j.jag.2007.04.002

    http://www.chesapeake.towson.edu/landscape/urbansprawl/download/Sprawl.white%20paper.pdfhttp://www.chesapeake.towson.edu/landscape/urbansprawl/download/Sprawl.white%20paper.pdfhttp://www.censusindia.net/http://www.censusindia.net/http://dx.doi.org/10.1016/j.jag.2007.04.002http://dx.doi.org/10.1016/j.jag.2007.04.002http://www.censusindia.net/http://www.censusindia.net/http://www.chesapeake.towson.edu/landscape/urbansprawl/download/Sprawl.white%20paper.pdfhttp://www.chesapeake.towson.edu/landscape/urbansprawl/download/Sprawl.white%20paper.pdf
  • 8/12/2019 Grupo 1 Monitoring Urban Sprawl Using RS &Amp; GIS

    18/18

    Stuckens, J., Coppin, P.R., Bauer, M.E., 2000. Integrating contextual

    information with per-pixel classification for improved land cover

    classification. Remote Sens. Environ. 71, 282296.

    Sudhira, H.S., Ramachandra, T.V., Jagadish, K.S., 2004. Urban

    sprawl: metrics, dynamics and modelling using GIS. Int. J. Appl.

    Earth Observ. Geoinform. 5, 2939.

    Sugumaran, R., Pavuluri, M.K., Zerr, D., 2003. The use of high

    resolution imagery for identification of urban climax forest speciesusing traditional and rule based classification approach. IEEE

    Trans. Geosci. Remote Sens. 41 (9), 19331939.

    Torrens, P.M., Alberti, M., 2000. Measuring sprawl. Working paper

    no. 27, Centre for Advanced Spatial Analysis, University College,

    London.http://www.casa.ac.uk/working papers/.

    Trani, M.K.,Giles,R.H., 1999.An analysis of deforestation: metrics used

    to describe pattern change. Forest Ecol. Manage. 114 (2), 459470.

    Vogelmann, J.E., Sohl, T., Howard, S.M., 1998. Regional character-

    izations of land cover using multiple sources of data. Photogr. Eng.

    Remote Sens. 64, 4557.

    Weng, Q., 2001. Modeling urban growth effects on surface runoff with

    the integration of remote sensing and GIS. Environ. Manage. 28

    (6), 737748.

    Yang, X., Liu, Z., 2005. Use of satellite derived landscape imper-

    viousness index to characterize urban spatial growth. Comput.Environ. Urban Syst. 29, 524540.

    Yang, X., Lo, C.P., 2003. Modelling urban growth and landscape

    changes in the Atlanta metropolitan area. Int. J. Geogr. Inform.

    Sci. 17 (5), 463488.

    Yeh, A.G.O., Li, X., 2001. Measurement and monitoring of urban

    sprawl in a rapidly growing region using entropy. Photogr. Eng.

    Remote Sens. 67 (1), 83.

    M.K. Jat et al. / International Journal of Applied Earth Observation and Geoinformation xxx (2007) xxxxxx18

    + Models

    JAG-168; No of Pages 18

    Please cite this article in press as: Jat, M.K. et al., Monitoring and modelling of urban sprawl using remote sensing and GIS

    http://www.casa.ac.uk/working%20papers/http://www.casa.ac.uk/working%20papers/