International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XXXIX-B4, 2012
XXII ISPRS Congress, 25 August — 01 September 2012, Melbourne, Australia
2.1.Water Resources Regions in India !5
Region Water resources Region Name
No
1 Indus River Region
2 Ganges River Region
3 Brahmaputra River
Region
4 Region covering all east flowing rivers draining in
Bengal except Ganges and Brahmaputra.
S Region covering all rivers draining in Arabian sea
in... west.
6 Region covering the rivers having ephemeral
. drainage in Rajasthan desert
Figure.1. Water resources Regions in India!?,
Based on these codifications water resources region 5 in
Tamil Nadu and near by Kerala states is delineated in to
5A basin which drain in Arabian sea and water resources
region 4 in Tamil Nadu, Karnataka and Andhra Pradesh
states in to 4A,4B and 4C basins which drain in Bay of
Bengal.( Table 1).
Table 1.River Basins in Tamil Nadu!!
No. Basin Rivers covered Area States covered
Code by the Basin Sq. Rm.
No.
i 4A 38.740 Tami! Nadu and
Kerala
2 tB Cauve 72 000
3 4
126
56.200 Tamil Nadu,
in Arabian Sea Kerala,
Pondichery, and
Karnataka
2.2.Relation ship of Micro Watershed with Stream order,
Area & Watershed Code No
The basins were further delineated in to Catchment,
Sub Catchment and Watersheds. Tamil Nadu state has
about 230 water sheds. The watershed is indicated using
capital alphabets and numerals. The watersheds are
further delineated in to next level as sub watersheds, mini
watersheds, micro watersheds Gradel to Grade VII based on
the geo morphological characteristic of streams in the soil
watershed Atlas of Tamil Nadu which is now available in
the web site http://www.aedatlas.tn.nic.in The codification of
micro watersheds is done in the same pattern of A.N.Khosla
with alternate small alphabets instead of capital letters and
numerals. ( Table 2).
This Atlas removes the concept of delineation of
water shed based on area etc. Earlier there was a practice of
defining micro watersheds based on area. A watershed with
500ha is termed as micro watershed without considering
geomorphology. A micro water shed may be large covering
1000 ha in plains and small covering 100 ha to 10 ha in
hills based on drainage pattern with the ridge of the micro
watershed as the permanent natural boundary.
3.MICRO WATERSHED
3.1.Micro watershed definition
MICRO WATER SHED is defined as that one
generally formed by second order streams because 1° order
streams are virgin drainage courses for water by fluvial
erosion process of sheet, rill and gully erosion and the I*
order stream is young and may not stabilized. This
assumption also avoids the codification of very tiny
watersheds in hills with dendritic or sub dendritic drainage
pattern. Stream adopts generally parallel and sub parallel
pattern in irrigated command areas and plains. The drainage
or feeder channels from the lakes or rivers are considered as
first or second order streams to evaluate and study stream
morphology.
3.2. Terminology!’ —Codification of watershed 4C2C4
The terminology of 4C2C4 Kusasthalai watersheds and
Poondi Reservoir -Ramancheri mini watershed 4C2C4bl is detailed
below
Region : 4 Rivers draining in Bay of Bengal ,
Basin: C Between Cauvery and Krishna
Catchment: 2 Between Pennaiyar and Pennar
Sub Catchment: C Miscellaneous around Chennai
Watershed: 4 Kosasthalai Aru
Sub Watershed: b Ramanjeri
Mini watershed: 1 Poondi Reservoir- Ramanjeri
The correlation between code number of micro
watersheds, their area and stream order is explained in Table
No 2. The micro watershed in plains may have 9'^ or lesser
stream order. Where as at hilly region it may be above 14%
order as we can identify more streams while using high
resolution satellite data and delineating micro water sheds.
This precision in delineation is not feasible while using
1:50000 topo graphic sheets with about 22 m resolution data
of Land sat , IRS LISS 3 or other satellites..
We
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