Field Strategy for Agricultural Drainage and Water-Quality Management

Abstract

An integrated irrigation-drainage design and management system is developed and applied to a hypothetical farm representative of the field conditions of the San Joaquin Valley (SJV), Calif. through computer simulations. The system is a departure from the traditional ways in which irrigation-drainage systems are designed and managed to satisfy not only the traditional agricultural objective (i.e., crop productivity), but also water-quality protection. The strategy is composed of a series of no-drainage and drainage cycles in which the former is an extended period in which drains are not operated; the latter is a limited period in which drains are allowed to release drainage water. The results of the computer simulations show that the integrated system can sustain crop productivity while reducing drainage water by 50–58% over a simulated eight-year period. It also leads to the overall improvement of the efficiency of the drains to intercept salt, thereby preserving current salt balance of traditional systems. A cost-benefit analysis has shown that the integrated system is economically more attractive than the traditional system.