562
information system is a chain of operations starting
from planning the observation and collection of
data, storage and analysis of the data, to the use
of the derived information in some decisionmaking process. A GIS is an information system
which is designed to work with data referenced to
spatial or geographical coordinates.
26.5 Methodology
Standard methodologies are adopted. Salient features of methodology adopted are as follows:
(a) Database creation and organisation through
generation of spatial framework in GIS
environment
(b) Geo-referencing of satellite data
(c) Identifi cation of wetland classes as per the
classifi cation system given in a standard (e.g.
NWIA) manual and mapping of the classes
using a knowledge-based digital classifi cation
and on-screen interpretation
(d) Generation of base layers (rail, road network, settlements, drainage, administrative
boundaries) from satellite image and ancillary data
(e) Mosaicing/edge matching to create database
at different levels
(f) Coding of the wetlands following the standard classifi cation system and codifi cation as
per the (NWIA) manual
(g) Preparation of map
26.6 Creation of Spatial
Framework
This is one of the most important tasks. To create
NWIA database, NNRMS/NRDB standards are
followed. Spatial framework details are given in
NWIA manual.
26.7 Geo-Referencing
of Satellite Data
In this step, the raw satellite images are converted
to specifi c map projection using geometric correction. This is done using archive geometrically
corrected LISS III data (ISRO-NRC land use/
land cover project). Standard image processing
softwares are used for geo-referencing.
26.8 Mapping of Wetlands
The wetlands are delineated through image
analysis. These formed the foundation for
deriving all wetland classes and results.
Consequently, a great deal of emphasis had
been laid on the quality of the image interpretation. The mapping of the wetlands is done following digital classifi cation and on-screen
visual interpretations. Wetlands are identifi ed
and noted based on vegetation, visible hydrology and geography. There are various methods
for extraction of water-related information
from RS imageries, which are generally classifi ed into two categories based on the number of
bands used, namely , (a) single-band and (b) multiband methods. The former method usually
involves choosing a band from multispectral
image to distinguish water from land by subjective
threshold values. It may lead to over- or underestimation of open-water area. The latter
method takes advantage of refl ective differences of each band. In this project, fi ve indices,
which enhance various wetland characteristics,
were used.
26.8.1 Inventory Application
The first step in developing a GIS application
is making an inventory of the features for a
given geographical area. These features are
represented in GIS as layers or themes of data.
The emphasis at this stage of application
development consists of updating and simple
data retrieval.
26.8.2 Analysis Application
Upon completion of the inventory stage,
complex queries on multiple layers can be performed using spatial and aspatial analysis
techniques.
26 Habitat Mapping of the Wetlands on GIS Platform
information system is a chain of operations starting
from planning the observation and collection of
data, storage and analysis of the data, to the use
of the derived information in some decisionmaking process. A GIS is an information system
which is designed to work with data referenced to
spatial or geographical coordinates.
26.5 Methodology
Standard methodologies are adopted. Salient features of methodology adopted are as follows:
(a) Database creation and organisation through
generation of spatial framework in GIS
environment
(b) Geo-referencing of satellite data
(c) Identifi cation of wetland classes as per the
classifi cation system given in a standard (e.g.
NWIA) manual and mapping of the classes
using a knowledge-based digital classifi cation
and on-screen interpretation
(d) Generation of base layers (rail, road network, settlements, drainage, administrative
boundaries) from satellite image and ancillary data
(e) Mosaicing/edge matching to create database
at different levels
(f) Coding of the wetlands following the standard classifi cation system and codifi cation as
per the (NWIA) manual
(g) Preparation of map
26.6 Creation of Spatial
Framework
This is one of the most important tasks. To create
NWIA database, NNRMS/NRDB standards are
followed. Spatial framework details are given in
NWIA manual.
26.7 Geo-Referencing
of Satellite Data
In this step, the raw satellite images are converted
to specifi c map projection using geometric correction. This is done using archive geometrically
corrected LISS III data (ISRO-NRC land use/
land cover project). Standard image processing
softwares are used for geo-referencing.
26.8 Mapping of Wetlands
The wetlands are delineated through image
analysis. These formed the foundation for
deriving all wetland classes and results.
Consequently, a great deal of emphasis had
been laid on the quality of the image interpretation. The mapping of the wetlands is done following digital classifi cation and on-screen
visual interpretations. Wetlands are identifi ed
and noted based on vegetation, visible hydrology and geography. There are various methods
for extraction of water-related information
from RS imageries, which are generally classifi ed into two categories based on the number of
bands used, namely , (a) single-band and (b) multiband methods. The former method usually
involves choosing a band from multispectral
image to distinguish water from land by subjective
threshold values. It may lead to over- or underestimation of open-water area. The latter
method takes advantage of refl ective differences of each band. In this project, fi ve indices,
which enhance various wetland characteristics,
were used.
26.8.1 Inventory Application
The first step in developing a GIS application
is making an inventory of the features for a
given geographical area. These features are
represented in GIS as layers or themes of data.
The emphasis at this stage of application
development consists of updating and simple
data retrieval.
26.8.2 Analysis Application
Upon completion of the inventory stage,
complex queries on multiple layers can be performed using spatial and aspatial analysis
techniques.
26 Habitat Mapping of the Wetlands on GIS Platform