City Sanitation Plan, Uttarakhand Detailed Plan report, Muni Ki Reti 1

City Sanitation Plan, Uttarakhand
Detailed Plan report, Muni Ki Reti
C = the runoff coefficient of the ratio between the
maximum rate of runoff and the average rate of rainfall during the time of concentration.
I = the average rain fall intensity in mm per hour for
the period of maximum rain fall off a given frequency of occurrence having a duration equal to the
time of concentration.
The drainage area A in hectare can be measured from Topographical plan or maps however
proper values of C and I must be estimated from the recorded data and experience.
(A) Run off Coefficient:-
The value of c will depend upon general soil condition of the area, typical rain fall
characteristics condition of surface and degree of land development both present and future the
various values of runoff coefficient to be adopted conditions is given as below :-
Runoff Co efficient Of different Surfaces
Table 4.2 showing various runoff co-efficient for types of surfaces
Type of surfaces Runoff co-
efficient
Water tight roof surfaces 0.7 to 0.95
Asphalt pavement in good order 0.85 to 0.90
Stone of brick pavements in cement mortar:-
(Good quality) 0.75 to 0.85
(Good jointed) 0.50 to 0.70
(Good quality) 0.40 to 0.50
Macadam Roadways 0.25 to 0.60
Gravel Roadways and Walks 0.15 to 0.30
On paved surfaces railroad and vacant lots 0.10 to 0.30
Parks, Gardens, lawns meadows (depending
upon the surface slops and soil
characteristics
Wooden areas of forest land depending as
before
0.25
0.01 to 0.20
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