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Flat land soils in Southern Ontario are used for the production of cash crops such as corn, soybeans and wheat. In their natural state, many of these soils are poorly drained. It is essential that these soils be artificially drained to grow these crops profitably. Selection of an appropriate drainage coefficient is required for the design of subsurface drainage systems. The drainage coefficient is the drainage rate which will provide adequate drainage of the soil for crop production under given soil, water table and crop conditions. Currently, the selection of a drainage coefficient is based on experience and judgment. Van Schilfgaarde (1965) presented design criteria in terms of a probability distribution of water table heights induced by rainfall. Kraft and Molz (1972) developed a design procedure based on a stochastic analysis of the rainfall-tile flow process. In the analyses, hydraulic conductivity, rainfall rate and drainage coefficient were treated as random variables. In this paper a model is developed to predict drainage rates (cm/day) for non-freezing periods, based on an analysis of the rainfall-runoff process, for a flat tile-drained agricultural basin near Merlin, Ontario. The paper outlines a procedure for the selection of an appropriate drainage coefficient using a probability analysis of drainage rates.
a model to determine a subsurface drainage coefficient for flat land soils
Sharma, T.C. and R.W. Irwin 1976. A MODEL TO DETERMINE A SUBSURFACE DRAINAGE COEFFICIENT FOR FLAT LAND SOILS. Canadian Agricultural Engineering 18(1):46-48.
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