.Infiltration

Infiltration Rate=Ic If [Ic < i ]

= i If [Ic > i ]
Surface runoff=Rainfall - (Infilitration + Surface retention)


Infiltration: The movement of water through the soil surface in to the soil.

Infiltration capacity(IC,mm/hr.): The ma
Surface retention (Interception + depression Storage)
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Infiltration Capacity Measurments:

1.Infiltrometer:

Ic=Rate of disappearance of water.

Ic=fa+(fo-fa)*e-kt (Horton equ.)
Where:
fo=initial Ic at t=0
fa=final Ic (constant value)


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2.Infiltration indices:
a. The w-Index:

W=(P-R)/t

b.The ?-Index:the rainfall intensity above which the rainfall volume
equals the runoff volume
Example1: Find the Index of a certain catchment has the change of the rainfall intensity which given below. If the runoff=33mm, P=75mm