Question

The infiltration capacity of soil in a small watershed was found to be 7 cm/h before a rainfall event. It was found to be 1.4 cm/h at the end of 8 hours of storm. If the total infiltration during 8 hours period of storm was 20 cm , then the value of the decay coefficient $k_h$ in Horton's infiltration capacity equation is

• A. 0.82/hour
• B. 0.43/hour
• C. 0.64/hour
• D. 1.2/hour

Answer 1

The correct option is C 0.64/hour

For large t values
$F_P=f_c.t+\frac{f_0-f_c}{k_h}$
Given ,
$F_P=20cm,f_0=7cm/h,f_c=1.4cm/h,t=8hours$

$\therefore 20=(1.4\times 8)+(7-1.4)/k_h$

$k_h=0.636/hour$
$\simeq 0.64/hour$