Abstract
An optimization model consisting of minimization of total cost of a pipe drainage system subject to constraints on
design variables was formulated. Data from Mardan SCARP was used as input to the optimization model. The
output was obtained in the form of various combinations of design variables with total cost. The optimal values for
lateral depth, spacing, diameter and length were found to be 1.60 m, 66.7 m, 9.20 cm and 250 m, respectively
which resulted in a total of 60 laterals and 2 collectors for an area of 100 ha. Collector diameter and length
respectively were 25.0 cm and 1000 m with a minimum cost of RS.28152/ha. As expected the laterals were of the
smallest size i.e., 9.20 cm to keep the total cost minimum. The optimization procedure was also used to identify
the nearly-optimal designs. The cost of nearly-optimal designs being close to the minimum cost showed these
designs equally good which shows the flexibility of the procedure to find out number of equally feasible designs.
