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3I/15NE, NW,
le and IRS-1C,
1:50,000 scale
IAPRS & SIS, Vol.34, Part 7, *Resource and Environmental Monitoring", Hyderabad, India, 2002
covering sheet No. 831/10,11,14,15 & 16 of dated 24.02.1997 have
been procured from National Remote Sensing Agency, Hyderabad.
Visual interpretation of IRS-1C, PAN data on 1:25,000 scale have
been carried out for delineation of different landuse/land cover
categories based on its tone, texture, contrast, shape, size,
pattern/association etc. — IRS-1C, LISS-III FCC data were
consulted and used for increasing accuracy of thematic maps. A
base map prepared on polyester-based tracing paper was
superimposed on to the PAN data.” Permanent features such as
road, railway, canal, embankment etc marked on to the base maps
were matched with the satellite data and landuse/land cover maps
were prepared on 1:25,000 scale. The tonal contrast of land water
boundary is sharp in PAN data, water appears in grey to black
tone, sand bar shows bright whitish tone, sand bar with grasses
shows light grey tone, moist sand show moderate grey tone, tea
garden, cropland, forest land etc have been identified based on its
characteristic variation in grey tone, shape, size, pattern &
associations etc. Interpreted landuse/land cover maps prepared on
1:25,000 scale were field checked in the month of December,
1997. Field data related to different types of vegetation, crop etc
were collected and incorporated in the final maps. Collateral data
pertaining to climate and relevant literature etc. were collected from
different Organization.
4. RESULTS AND DISCUSSION
IRS-1C, PAN data on 1:25,000 scale of 24.02.1997 have been
used for delineating different categories of landuse/land cover in
parts of Dibrugarh, Dhemaji and Sibsagar districts of Assam. In
level-I interpretation, six major categories such as built-up land,
agricultural land, forests, wetlands, wastelands, and other
categories were identified. In level-II interpretation, these six
major categories have been further classified into different sub
categories. — Plate-1 shows landuse/land cover map of sheet
No.83I/1 INE & Plate-2 shows landuse/land cover map of sheet
no.83I/15NW.
4.1 Built-up Land: All man made constructions such as
residential, industrial, recreational areas or for transportation,
communication etc. are included in this category. These
categories have been further classified as urban, rural, industrial,
open/vacant land.
4.2 Agricultural Land: Agricultural land comprises area used for
raising agricultural crops, fiber, vegetable, fruits, cultivable fodder
and other plant material of medicinal and commercial value.
Agricultural land is widely distributed throughout the study area
and agriculture is the main economic base of the Assam. The
agriculture land is further classified as cropland in alluvial area,
cropland in flood plain area, cropland in old meander area,
cropland in paleo channel, tea garden and other plantation. Most
part of the study area are flat, gently sloping alluvial terrains
mainly used for agricultural purposes. Single crop practice is most
common in the area. Some of the areas are cultivated during Rabi
season mainly for paddy. Assam is also known all over the world
for its beautiful tea gardens. Satellite data can be used in acreage
and condition assessment of tea plantations in the region. About
53 tea gardens having areal extent of 12994.76 ha have been
mapped from PAN data in parts of Dibrugarh and Sibsagar
districts of Assam. A vast alluvial tract is used for tea gardens. A
large part of cropland & forestland has been converted into tea
gardens over the last 30 years. The other plantation includes
arecanut, coconut, banana plantations and bamboo groves. These
plantations generally confined near the settlements in villages
where most of the houses are surrounded by the trees. However,
bamboo groves are also spread out in cropland area.
585
4.3 Forest Land: Forest is defined as all lands bearing vegetative
association dominated by trees of any size, exploited or not,
capable of producing wood or other forest products and exerting
an influence on climatic or water regimes or for providing shelter
for wild life or livestock. Three main sub categories of forest land
were delineated from PAN data includes Evergreen/Semi
evergreen forests, Deciduous forests and Degraded scrub land.
Most of the forests in the study area are mixed forests, which bear
. an association of both evergreen/semi evergreen and deciduous
trees. Dihingmukh, Diroi, Jokai, Namdang etc reserved forests are
good example of mixed evergreen and semi evergreen forests in
parts of Dibrugarh and Sibsagar disricts of Assam. It includes
evergreen trees like Dipterocarpus macrocarpus, Shorea robusta,
Mesua ferra, Amnores wallichi, Cinnamomm ceciclodapana,
Dubanga sonnecrationdes, Cedrelatona etc. Deciduous forest
include trees like Terminalia myriocarpa, Bishafia javanica,
Dillonia indica, Terminalia belerica etc. Degraded/scrub lands
are most commonly associated within notified forest areas.
4.4 Wetland: All submerged or water saturated lands, natural or
man made, inland or coastal, permanent or temporary, static or
dynamic, vegetated or non vegetated which necessarily have a
land water interface are identified as wetlands. River/stream, dry
river/ stream, oxbow lake/cut off meander, pond/lake,
marshy/swampy, surface waterlogged land etc wetlands were
delineated from PAN data and shown in respective maps.
4.5 Wasteland: Wastelands are defined as degraded lands, which
can be brought under vegetative cover with reasonable effort and
are currently under utilized lands. Marshy/swampy and surface
waterlogged wastelands were delineated under wetlands category.
Wastelands in the study area delineated are further identified as
gullied/ravinous land, land with or without scrub, braid bars and
bank bars. Bars are further classified & delineated as braid bar
with moist sand, braid bar with dry sand, braid bar with grasses,
submerged bars, bank bars with moist sand, bank bar with dry
sand and bank bar with grasses.
4.6 Grassland/Grazingland: Grass land/grazing lands are area of
natural vegetation dominated by grasses or grass like plants and
non grass like herbs generally known to occur on both banks of the
Brahmaputra river and shown in sheet No. 831/11 NE and 831/15
NW.
4.7 Transportation Network: IRS-1C, PAN data were used for
delineating existing transportation network in the study area which
include. major road, all rural road, railway line, railway
station/yard, embankment/bund, canal, drainage etc. The southern
bank of the Brahmaputra river near Bogibilgaon in Dibrugarh
district and northern bank of the Brahmaputra river near Rajapur
in Dhemaji district is proposed to be connected by constructing
multi purpose rail cum road bridge across Brahmaputra river and it
is to be connected with existing railway line & roads in Dhemaji,
Dibrugarh and Sibsagar districts of Assam.
The proposed multipurpose road and rail bridge site alignment
joining existing railway & road network is superimposed on final
landuse/land cover maps which have provided information on
landuse/land cover in the vicinity of proposed road and rail
alignment sites. It is observed that the northern bank of the river
near proposed km 19 of road alignment and km 31 of rail
alignment, the Brahmaputra river has witnessed a sudden shift in
its flow which has breached embankment near village Rajapur,
therefore, a proper measures are required to arrest further
northward shift of the Brahmaputra river in this region. Two
alternate bridge site along Dignalagaon-Pamuagaon & Tinsukia-
