A procedure combining simulation and mathematical programming to derive an optimal irrigation system design given scarce resources is described. A hydraulics simulation model for surface irrigation was used to develop relationships between water requirement efficiency and the system design variables. A crop production function was used to relate crop yield to the water requirement efficiency, while gross returns from the crop and the costs of water, labor, ditch construction, and crop production were considered in determining the combination of water requirement efficiency and design variables yielding optimum net benefit. Several system constraints (e.g., length and slope of field, infiltration) were incorporated into the design process. Generalized geometric programming was applied to the optimal design of border and basin irrigation systems, using the length of run, inflow rate into the border, time of inflow, number of lengths of run, width of the border, and the number of border widths in the field as the design variables. Thirteen references (1960-80) and a 7-page bibliography of related technical reports and manuals are provided. (Author abstract, modified).