ABSTRACT
Methods have been used over the centuries to guide the design and installation of drainage systems. These methods range from simple guidelines that relate drainage requirements to soil types, to computer programs that simulate long-term day-to-day performance of drainage systems in response to weather conditions and management practices. Our discussion here will be limited to groundwater equations that are applied to drainage and to the computer models that use these equations to simulate drainage systems. More detailed reviews of drainage models and their applications are available to the reader.[1-3]
The primary objective of drainage is to provide a favorable environment for crop production; therefore, development of drainage models has depended on formulations of equations to describe movement of shallow groundwater. Models have progressed with advances in math, science, and computer technology toward more accurate solutions of increasingly complex equations and boundary conditions. Technological advances have also made possible more rigorous treatment of other important processes such as crop growth, evapotranspiration, and rainfall that vary with time. The resulting models can simulate the performance of various drainage system designs over long periods of time and evaluate system performance in terms of specified objective functions, such as crop yield and profit.
