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M.TECH (ENV. ENGG), SEM – II REMOTE SENSING AND GEOGRAPHICAL INFORMATION SYSTEM

UNIT - V (Part – B)

1. DESCRIBE APPLICATION OF GIS IN MONITORING OF ENVIRONMENT AND LAND USE AND ITS

ADVANTAGES AND LIMITATIONS.

Remote sensing (RS) data coupled with fieldwork information and geographic information systems (GIS)

have been recognized as effective tools in quantitatively measuring spatial patterns of LULC over

relatively large geographic scales. Transitions in architecture and building density, vegetation and

intensive socioeconomic activities at the block level in cities often transform the urban landscape

towards heterogeneity. Therefore, the urban environment represents one of the most challenging

GIS APPLICATIONS IN LAND USE:

Knowledge of land use and land cover is important for many planning and management activities and is

considered an essential element for modelling and understanding the earth as a system. Land cover

maps are presently being developed from local to national to global scales. The use of panchromatic,

medium-scale aerial photographs to map land use has been practiced since the 1940s (Lillesand, Kiefer,

& Chipman, 2008). Remote sensing has long been used to map urban growth and urban morphology,

and implies the mapping of the form, land uses, and density of urban areas, each having an associated

shape, configuration, structure, pattern, and organization of land use. Sometimes simply mapping an

urban or non-urban dichotomy is important; while sometimes detailed morphologic mapping is needed,

where the positions of buildings and roads or the extraction of the three-dimensional topographical

aspects of urban areas are needed. Satellite imagery has the unique ability to provide synoptic views of

large areas at a given time that is not possible using conventional survey methods. The term land cover

refers to the type of feature present on the surface of the earth. Forest, lakes, concrete highways, ice

sheet are all examples of land cover types. While the land use refers to the human activity associated

with a specific piece of land. For example, a tract of land on the fringe of an urban area may be used for

single-family housing. Depending on the level of mapping detail, its land use could be described as

urban use, residential use, or single-family residential use. The same tract of land would have a land

cover consisting of roofs, pavement, grass, and trees. Thus for a planner, a knowledge of both land use

and land cover (LULC) is necessary for planning and land management activities. Continues

advancement of remote sensing technologies and the increasing availability of high resolution earth

observation satellite data provide great potential for acquiring detailed spatial information to identify

LULC of urban regions.

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areas for remote sensing analysis due to the high spatial and spectral diversity of surface materials

(Thapa & Murayama, 2009a). In recent years, a series of earth observation satellites have provided

abundant data at high resolutions (0.6~2.5 m; QuickBird, IKONOS, OrbitView, SPOT and ALOS) to

moderate resolutions (15~30 m; ASTER, IRS and LANDSAT) for urban area mapping. Remote sensing

data from these satellites have specific potential for detailed and accurate mapping of urban areas at

different spatiotemporal scales. The high resolution imagery provides data for monitoring urban

infrastructures, whereas moderate resolution imagery can provide synoptic measures of urban growth,

surface temperature and more. A wide range of urban remote sensing applications from both sensors is

available to date. These include quantifying urban growth and land use dynamics, population

estimation, life quality improvement, urban infrastructure characterization, monitoring land surface

temperature, air quality and vegetation, and topographic mapping. Having the potential to monitor

human activities at the earth surface, however, the information acquired from remote sensing data

could be an additional resource in developed economies, while it might be the only alternative in the

developing countries.

GIS AND ENVIRONMENTAL MODELING

Approaches represent how the existence or source of any hazard is modeled as risk in relation to

vulnerable receptors. This implies that both the source and the receptors have to be identified and that

there is some model of how that source impacts the receptors. A source may be identified as a specific

object (a smoke-stack, effluent outfall), a zone (unstable slope from which specific landslides may

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occur, an area of seepage, a fault line) or diffuse over the whole area (strong wind event, heavy

rainstorm). Generally the first of these would be classified as point sources and the latter two as non-

point sources. Difficulties arise over such an inductive classification because a non-point source in one

area may originate from a point source in another. Thus general air pollution in one area may originate

from specific factories elsewhere. Depending on the scale of study, it may not be possible to model all

the individual point sources but treat the aggregate effect as a non-point source. Point and non-point

sources need to be treated differently in GIS (point, line, polygon or field) and are likely to influence the

form of analysis. Receptors can be people, the flora and fauna, properties and land, again with different

ways of representing these in a GIS with consequences for the modelling. It is, however, the modelling

of the means by which the source has the ability to impact the receptors that is distinctive within the

taxonomy:

• Spatial coexistence – This approach assumes that there is a reasonably simple or obvious spatial link

between sources and receptors. Thus, for example, by taking the floodplain and overlaying it on

settlements one might infer that anywhere where object ‘floodplain’ and object ‘settlement’ spatially

coincided, people were vulnerable to a flood hazard. This approach relies heavily on conceptual and

empirical models.

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