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E-International Scientific Research Journal
ISSN: 2094-1749 Volume: 3 Issue: 2, 2011
(57 %), 24 stream orders have a value between 1 and 2 Km for first order streams and for others
Lu given in Table 2.
Drainage density (Dd): Drainage density (Dd) is the total length of the stream in a given
drainage basin divided by the area of drainage basin (Horton, 1932).
Dd= ∑L/A,
Where ∑L- total length of the stream,
A- Area of drainage basin.
Table 2 depicts the distribution of third order basins under different drainage density groups. The
Dd value of DRB is 1.82 Km/km 2 . The study of TOSBs revealed that average Dd is 2.67 km/km 2
and it varies in between 1.47 km/km 2 to 7.88 km/km 2 (Table-2). The highest Dd is for the TOSB
15, 16, 20, and 22. With a value of 7.37, 7.42, 6.76, 7.88 respectively is situated nearest to the
highest rainfall occurring region such as Ghughukhan ,Maniya and Binayak. The TOSB 10 with
lowest Dd value with 1.44, nearer to the lowest rainfall occurring region such as Fathehpur. The
Table 3 reveals the relationship between rainfall and Dd. At present Ghughukhan rain gauge
station records highest rainfall.
The Dd generally increases with rainfall (R)
Thus Dd ∞ R
Dd= KXR
Dd/R = K, where K is a constant and its value is always less than one
The Dd and R studies reveal that Dd controls runoff following a particular period of
precipitation and the increasing Dd shows increasing size of mean annual flood.
Table 3: Relation of rainfall and drainage density (Dd)
Code
of
TOS
B
Dd Nearest
Rain Gauge
Annual
mean
Rainfall
(mm)
22 7.88 Ghughukhan 2749.80
13 3.16 Maniya 2357.10
10 1.47 Aniya 854.06
Data
Recorded
5Year (2005-
2010)
5Year, (2005-
2010)
5Year, (2005-
2010)
Stream frequency (Df): It is the number of stream segments per unit area (Horton, 1932, 1945).
The stream frequency, Df = ∑N/A, where N is the number of stream segments and A denotes the
drainage area. The average Df for DRB is 2.45. The lowest Df value is for the TOSB 8 with a
value of 8.67 and the highest for the TOSB 20 with a value of 18.82. The frequency value wise
numbers of TOSBs are tabulated (Table 2)..
Relation between Drainage Density and Frequency: The relation of Dd and Df revealed that
the Df is directly proportional to Dd (Table 4) Thus drainage frequency is double the value of
drainage density and its variation occurs due to rainfall, relief, infiltration rate, and initial
resistivity of terrain to erosion, total drainage area of the basin and above all the Dd of the basin
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