ABSTRACT
Knowledge of water flow under saturated conditions is important to engineers, soil scientists, and agronomists. The data on volume and rate of flow of water in soil are needed for managing soils and plant growth. The water movement through a soil system influences aeration, nutrient availability to the plants, and soil temperature. Important applications of saturated flow in farmlands involve design of a surface and subsurface or tile, drainage system in a watershed. Most drainage designs are based on steady flow under saturated conditions. The tile spacing can be calculated from the known values of saturated hydraulic conductivity (Sec. 12.2), soil texture, and drainage design parameters. Other applications of saturated hydraulic conductivities are in the scaling of soil hydrological parameters and relationships. However, hydraulic conductivity varies strongly in space and time across the field. The magnitude of variability must be considered in all hydrological designs. The information of saturated flow is also useful for engineers constructing earthen dams, canals, water-ways, etc. Failure of a dam, often caused by excessive flow through it, can have drastic consequences downstream. In agricultural fields, saturated flow occurs under rice paddy conditions. Excessive seepage losses decrease water efficiency and necessitate repeated and frequent irrigation, which lead to a rise in the water table with attendant risks of secondary salinization.
