A systems approach to drainage reduction in the San Joaquin Valley

Abstract

The subsurface drainage problems of the San Joaquin Valley of California, U.S.A. require that substantial drainage reduction be achieved through irrigation and drainage water management. Drainage reduction in the valley must be a systems approach in which all components of water management must be considered. These components include irrigation system design and operation, irrigation scheduling, drain water use for crop production, and leaching/drainage. Keys to drainage reduction through irrigation water management are improving the uniformity of the applied water and reducing the average depth applied. Uniformity can be improved by upgrading existing surface irrigation systems or converting to sprinkler or drip/trickle systems. The average depth applied can be reduced by improved irrigation water management, such as reduced set times and better irrigation scheduling. Drain water use for crop production can also reduce subsurface drainage. Strategies for drain water use include irrigation with saline water and water table management. However, the leaching/drainage requirements must be considered when implementing these strategies.