To find out net amount of rain it is required to analyses the amount of losses. Infiltration is a loss to us when net rainfall is concerned. As a water resource engineer it is important for us to know the amount of losses so that to know the amount of rain which is ultimately joining the stream or river and accordingly we can design the hydraulic structures.
To understand the concept with clarity it’s important to understand two things:-
Types of Infiltration Index
Infiltration is the movement of water through soil. It is the process by which water enters into surface strata of soil to meet initial soil moisture deficiency
Infiltration Index is a method used for Measurement of Infiltration. It represents average rate of infiltration. There are two types of infiltration index:-
ᵠ- Index – It represents average infiltration rate during the period of rainfall excess. In the calculation of ᵠ- Index initial losses is also considered as infiltration quantity.
W-Index- This is the average infiltration rate during the entire/whole period of storm. In the calculation of W-Index initial loss is separated from the total infiltration.