According to Horton (1945) drainage density
is the total stream length per unit area of a basin.
the drainage density
of each SHB was calculated whose value is attributed from the relation between the total length of the channels and total area of the basin.
is the variable that completes the set of variables proposed for the composition of TESI.
Important areal, linear and relief parameters were computed such as perimeter, basin area, basin length, drainage density
(Dd), stream frequency (Fs), elongation ratios (Re), bifurcation ratio (Rb), circulatory ratio (Rc) etc.
As stated by Costa (1987), the number of flood events greatly reduces as a function of drainage area A and drainage density
[D.sub.d] and flood peak tends to increase as a function of elongation ratio [R.sub.e].
These parameters comprise the compression factor, form factor, elongation factor, streams frequency, drainage density
, Bifurcation Ratio, drainage texture, concentration time and basin shape, all of which corresponding to the drainage network of the basin.
The mean pressure in the drainage cavity and drainage density
were 34.5 [+ or -] 2.9 cmH[sub]2O and 1.1 [+ or -] 0.1 g/m [sup]3, respectively.
To improve model fitting, various geoenvironmental factors like lithology, slope, aspect, lineament density, drainage density
, weathering, soil depth, terrain units, road buffer, and land cover were considered as covariates .
These units can be expressed regarding the slope of the area, runoff characteristics, drainage density
, stream frequency and relief ratio of the area (Babar, 2005).
Topographic maps provided information on the drainage network and watershed limits which were used to compute maps of drainage density
(DD) distribution and a watershed distance.
(D): The ratio of total channel length of all orders to the area of the basin is defined as Drainage Density
(Strahler 1958 Vijay 2003 Bassey and Joel 2010).
In order to evaluate the hazard probability of the different basins, some of the morphometric parameters were used these morphometric parameters include drainage density
, drainage frequency and bifurcation ratio.