Infiltrometer is used for field measurement of infiltration. There are two types of infiltrometer ? Single ring infiltrometer and Double ring infiltrometer. Single ring infiltrometer always overestimate because of lateral movement of water and to overcome this double-ring infiltrometer is used.

Rainfall simulators are used for laboratory measurement of infiltration and Infiltrometer is used for field measurement of infiltration. Lysimeter is used to measure evapotranspiration and tensiometer is used to measure capillary potential.

The rate of infiltration is directly proportional to temperature. As temperature increases, viscosity decreases and resistance to flow decreases and infiltration increases.

Soils having small pore size such as clay have low infiltration capacity than soils having large pore size such as sandy soil. One exception is when clay is present in dry conditions; soil can develop large cracks which lead to higher infiltration capacity.

The rate of infiltration measured by infiltrometer is more than infiltration rate determined by rainfall simulator. The rate of infiltration is directly proportional to depth of surface retention. As depth of retention is more in infiltrometer hence rate of infiltration is more in infiltrometer.

Infiltration is process by which water seeps into surface strata of earth to meet soil moisture deficiencies. Percolation is deep vertical movement of water in ground.

Grass cover or vegetation cover increases field capacity by trapping water and reducing effect of raindrop compaction. Vegetation and grass cover also reduces surface compaction of soil which again allows for increased infiltration.

Horton?s equation assumes an infinite water supply at surface i.e. it assumes saturation conditions at soil surface. The infiltration rate at any time?t? is given by ?
f_t = f_C + (f_O ? f_C) e^-K.t
Where f_C = final constant rate of infiltration at saturation, f_O = initial rate of infiltration capacity, k is decay constant depending upon soil and vegetation and t = time from beginning of storm.

Culturable Command Area is basis for design of watercourse and basis for design of an irrigation project. The irrigation schemes in India are classified into three parts viz. Minor, Medium and Major Irrigation schemes depending upon areas involved. Major irrigation scheme is one where CCA involved in project is greater than 10,000 hectares.

The irrigation schemes in India are classified into three parts depending upon areas involving culturable command area.