what is mean by INFILTRATION and it's Measurements

in this video i have explained what is mean by INFILTRATION and it's Measurements like HORDEN infiltration capacity curve, Infiltrometer (single ring and double ring),Rainfall SIMULATORS and infiltration indices (pi-index,w-index) And also i have explained what is infiltration capacity of soil, rate of infiltration,what is the relation between intensity of rainfall and rate of infiltration. how to find the runoff depth by using pi-index curve. The infiltration rate is the velocity or speed at which water enters into the soil. It is usually measured by the depth (in mm) of the water layer that can enter the soil in one hour. An infiltration rate of 15 mm/hour means that a water layer of 15 mm on the soil surface, will take one hour to infiltrate. In dry soil, water infiltrates rapidly. This is called the initial infiltration rate. As more water replaces the air in the pores, the water from the soil surface infiltrates more slowly and eventually reaches a steady rate. This is called the basic infiltration rate (Table 7). The infiltration rate depends on soil texture (the size of the soil particles) and soil structure (the arrangement of the soil particles: see Volume 1) and is a useful way of categorizing soils from an irrigation point of view (see Table 8). The most common method to measure the infiltration rate is by a field test using a cylinder or ring infiltrometer.