Agricultural hydrology is the study of water balance components intervening in agricultural water management, especially in irrigation and drainage. where Rm is the maximum retention of the area for which the method is usedThe total irrigation and the infiltration are:The quantity of water to be drained in a normal winter is: Agricultural hydrology is the study of water balance components intervening in agricultural water management, especially in irrigation and drainage. The water balance components can be grouped into components corresponding to zones in a vertical cross-section in the soil forming reservoirs with inflow, outflow and storage of water: