Geomorphometric analysis of a hilly watershed in north east India
with stream order as one of the attribute data for
length, relief, length of streams, stream order was
the drainage layer. From the digitized boundary
then used to compute the morphometric parameters
and drainage lines, a drainage map (Figure 1) of
ofthewatershedusingthestandardformulae(Horton
the watershed was generated at 1:40,000 scale. The
1932, 1945, Miller 1953, Schumm 1956, Strahler 1964,
information on watershed area, perimeter, basin
Chopra et al. , 2005, Singh 2006) as given in Table 1.
Table 1. Formulae adopted for computation of morphometric parameters
Morphometric Parameters
Formula
Stream Order
Hierarchical rank
Stream Length (L u )
Length of the stream
Lsm = L u /N u
Where, Ls m = Mean stream length
Mean Stream Length (Ls m )
L u = Total stream length of order ‘u’
N u = Total number of stream segments of order ‘u’
R l = L u / L u-1
Stream Length Ratio (R l )
Where, L u = Total stream length of order ‘u’
L u-1
= Total stream length of its next lower order
Rb = N u / N u+1
Bifurcation Ratio (Rb)
Where, N u = Total no. of stream segments of order ‘u’
L u-1
= no. of stream segments of the next higher order
Mean Bifurcation Ratio (Rb m )
Rb m = Average of bifurcation ratios of all orders
Rh = H/L b
Where, R h = Relief ratio
Relief Ratio (R h )
H = Total relief of the basin in km
L b = Basin length
D = L u /A
Where, D = Drainage density
Drainage Density (D)
L u = Total stream length of all orders
A = Area of the basin (km 2 )
F s = N u /A
Where, F s = Stream frequency
Stream Frequency (F s )
N u = Total no. of streams of all orders
A = Area of the basin
R t = N u /P
Where, R t = Drainage texture
Drainage texture (R t )
N u = Total no. of streams of all orders
P = Perimeter of the basin (km)
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