The purpose of this report is to research the scientific literature and provide the state of knowledge on subjects that impact crop productivity with saline irrigation water and analyze the existing information from the South Delta and quantify how the various factors influencing the use of saline water applies to conditions in the South Delta.
There are five objectives for this study:
One of the objectives of this study is the review of existing literature relating to the effect of salinity on a variety of irrigated crops under South Delta conditions, preparation of a comprehensive list of references, and a synopsis of findings from key references.
A second objective is the review of the relative strengths and limitations of steady-state and transient models that have been used to determine the suitability of saline water for crop production. As part of this second objective, the strengths, limitations, and assumptions of each model when applied to field conditions are to be presented.
The third objective involves the use of soil information to determine and describe the approximate area and nature of saline and drainage-impaired soils; an estimate of the effectiveness of local rainfall in reducing the irrigation requirement; and compiling and evaluating historical crop types, acreages, and evapotranspiration information.
The fourth objective is to provide conclusions and recommendations to the State Water Resources Control Board based upon the literature, modeling, and data evaluation. Among the conclusions and recommendations to be reported the following are considered paramount. (1) Identify significant gaps or uncertainties in the literature and recommend future studies to fill the gaps. (2) Using a steady-state model and appropriate data for the South Delta, estimate the leaching fraction required for salinity control for crops regularly grown on the drainage- and salinity-impaired soils of the South Delta. (3) Using the approach as in (2), recommend a salinity guideline that could provide full protection of the most salt sensitive crop currently grown or suitable to be grown on the drainage- and salinity- impaired soils.
The final objective is to present the findings and recommendations in Sacramento to interested stakeholders and representatives of California state agencies.