Well,

he medium range is characterized in particular by containing membranous water, and it acts as a conductor between the waters of the area near the surface of the earth and the waters of the region near the water level in which the water movement is perpendicular to the bottom and the membranous water passes through it. Excess water that moves downward under the influence of gravity is called gravitational water.

        The sediments of the unsaturated range differ in terms of the degree of sorting and the size of the granules and therefore lead to a difference in the permeability and the filtering rate while the water moves downward due to gravity more freely in the homogeneous medium and is not hindered only by the pulling forces generated by the capillary property.

Regards

When water is added to a dry soil , it is distributed around the soil particles where it is held by adhesive and cohesive forces; it displaces air in the pore spaces, when all pores are filled the soil is said to be at its maximum retentive capacity. Water that moves freely in response to gravity and drain out of soil know gravitational water. Under cohesion force make possible a marked thickness of the film of water established by hydration until they attain microscopic size, As the film gets thicker and thicker the force of gravity act and water flows downward through the large pores. This water continuously move downward or lateral in the interment zone and finally meet unconfined aquafir.

I agree to the answer of Dr Ashok K Singh. I just want to add few more things-

A very general and simplified soil profile can be described as follows:

a. The plough layer (20 to 30 cm thick): is rich in organic matter and contains many live roots. This layer is subject to land preparation (e.g. ploughing, harrowing etc.) and often has a dark colour (brown to black).

b. The deep plough layer: contains much less organic matter and live roots. This layer is hardly affected by normal land preparation activities. The colour is lighter, often grey, and sometimes mottled with yellowish or reddish spots. c. The subsoil layer: hardly any organic matter or live roots are to be found. This layer is not very important for plant growth as only a few roots will reach it. d. The parent rock layer: consists of rock, from the degradation of which the soil was formed. This rock is sometimes called parent material.

The depth of the different layers varies widely: some layers may be missing altogether.

When rain or irrigation water is supplied to a field, it seeps into the soil. This process is called infiltration.

Infiltration can be visualized by pouring water into a glass filled with dry powdered soil, slightly tamped. The water seeps into the soil; the colour of the soil becomes darker as it is wetted.

The infiltration rate of a soil depends on factors that are constant, such as the soil texture. It also depends on factors that vary, such as the soil moisture content.

i. Soil Texture

ii. The soil moisture content

iii The soil structure

Generally speaking, water infiltrates quickly (high infiltration rate) into granular soils but very slowly (low infiltration rate) into massive and compact soils. During a rain shower or irrigation application, the soil pores will fill with water. If all soil pores are filled with water the soil is said to be saturated. There is no air left in the soil . The period of saturation of the topsoil usually does not last long. After the rain or the irrigation has stopped, part of the water present in the larger pores will move downward. This process is called drainage or percolation.

Part of the water applied to the soil surface drains below the rootzone (capillary zone) and feeds deeper soil layers which are permanently saturated; the top of the saturated layer is called groundwater table or sometimes just water table .