INFILTRATION & RUNOFF DEFINITIONS

 INFILTRATION & RUNOFF

Two important aspects of Hydrological Cycle are

1. Infiltration

2. Runoff

INFILTRATION

All precipitation will not become surface runoff.

Some quantity of precipitation infiltrates into the ground.

The infiltration plays a significant role on the relationship between rainfall and runoff.

If the soil is wet, less water infiltrates and more surface runoff is generated.

Similarly, if the soil is dry, more water (usually) is able to soak into the ground.

RUNOFF

The water left after infiltration flows overground as runoff

Volume of runoff depends on:

 Rainfall intensity and duration

 Type of surface (pervious or impervious)

 Area of catchment

Usually

(a) Low intensity rainfall - Mostly Infiltrates

(b) High intensity rainfall - Infiltrates and become surface runoff

Runoff depends on the catchment characteristics and can be related as

(a)Thick vegetation = low volume, slow runoff

(b) Paved area = high volume, fast runoff