Strategies for reducing subsurface drainage in irrigated agriculture through improved irrigation

The traditional approach of installing subsurface drainage systems to solve shallow ground water problems is not feasible along the west side of the San Joaquin Valley of California because of the lack of drain water disposal methods that are economical, technically feasible, andenvironmentally friendly. Thus, options such as drainage reduction through improve dirrigation and drain water reuse are being examined as methods for coping with the subsurface drainage problem. This paper discusses options for reducing subsurface drainage through improved irrigation practices. Options are discussed for improving irrigation system design such as upgrading existing irrigation methods and converting to systems with higher potential irrigation efficiencies. Methods for improving water management are also presented. Case studies on upgrading existing systems or converting to other irrigation methods are presented along with study results of the effect of various policies on reducing subsurface drainage.