Drainage equation

The drainage equation, often used in hydrology and soil physics, describes the movement of water through soil or other porous media. It is essential for understanding how water drains from the soil, which affects agricultural practices, irrigation, and groundwater management. One common form of the drainage equation is derived from Darcy's law, which relates the flow of water through a porous medium to the hydraulic gradient. The drainage equation can be expressed in various forms, depending on the context and assumptions made.