DESIGN OF AGRICULTURAL DRAINAGE WITH ADAPTIVE IRRIGATION MANAGEMENT

This paper describes a new approach to designing field-scale irrigatio n and drainage systems in arid irrigated areas. This approach allows f or a drainage design that can adjust to irrigation schedules to allevi ate waterlogging and salinity problems. This approach has been impleme nted in a computer model. The computer model contains a feedback loop between the irrigation scheduling and the drainage design components. The modular components of the system are a weather generator, irrigati on scheduling, upward flow, salinity of the irrigation water, transien t-state drainage design, and crop production. The model modifies the i rrigation schedule taking into consideration the effects on the draina ge design. The performance of the system is evaluated using the net be nefits, as well as explicitly addressing the stochastic nature of irri gation and drainage. The model is constructed so the irrigation and dr ainage components may be varied individually to study the impact on th e whole system. This capability will allow the user to quantify the co st of minimizing drainage water production by modifying the irrigation schedule.