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E-International Scientific Research Journal
ISSN: 2094-1749 Volume: 3 Issue: 2, 2011
Where H is the total relief and L b is the basin length. The R h value of DRB is 0.173. The low R h
values are resulted by resistant bedrock and low slope and R h values usually increases with
decreasing with decreasing drainage area (Table 2).
Elongation ratio (R e ): It is the ratio of diameter of a circle having the same area as of the basin
and maximum basin length (Schumm, 1956). The R e is given by
R e = d/Lb,
Where d is diameter of a circle having the same area as of the basin, and Lb maximum basin
length parallel to the principal drainage line. It is a measure of the shape of the river basin and
the value ranges between 0.6 and 1. Value ranges from 0.6 to 0.8 are regions of high relief and
the value close to 1.0 are regions of very low relief with circular in shape and are efficient in the
discharge of runoff than and elongated basin because concentration time is less in circular basins.
Thus R e values help in flood forecasting. The elongation ratio and shape of basin are given in
Table 5.
Table 5: Elongation ratio and shape of river
Elongation ratio
Shape of basin
0.9 Circular
Elongation ratio
Shape of basin