This lecture explores the processes of infiltration and percolation in soil. Infiltration measures the rate at which water enters the soil, typically expressed in inches or millimeters per hour, and is measured using an infiltrometer. Factors affecting infiltration include soil texture, vegetation, and slope, with coarse, porous soils exhibiting higher infiltration rates. Percolation refers to the movement of water through soil layers to reach groundwater, a process crucial for replenishing aquifers. Additionally, seepage involves the lateral and downward movement of water from sources like reservoirs and canals, influenced by soil characteristics, hydraulic factors, and physical conditions of the water source.