Author

Tom Al Austin

Date of Award:

1970

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Civil and Environmental Engineering

Advisor/Chair:

Frank W. Haws

Abstract

The purposes of this study were to evaluate the present irrigation efficiencies of the Bear River delta area of northern Utah and to propose a set of management proposals to improve the irrigation efficiency. In order to evaluate the present use, all pertinent data on the water resources of the Bear River delta had to be assembled and analyzed.

A hydrologic budget is a method used to account for all inflows, outflows, and changes in storage within a given area. In this study, all inflows and changes in storage were evaluated and the outflow was predicted. In this manner the management proposals could be tested to determine their effect on the outflow. The time base used in the budget analysis was chosen as monthly over the period 1931 - 1960. The mean annual outflow from the delta area to the Great Salt Lake was estimated to be 891,000 acre feet as surface outflow and 27,500 acre feet as groundwater outflow.

Irrigation requirement can be defined as the volume of water, measured at the point of diversion, required to meet crop potential consumptive uses. Irrigation requirement is a function of the system efficiency and includes the water "lost" from the conveyance and storage facilities. When compared to the present mean cropland diversions, a deficit or surplus water supply exists. These parameters were evaluated for both the present and the future estimated irrigation system efficiencies.

The present irrigation efficiency was estimated from potential consumptive use data and seepage loss data from surrounding areas. The present system efficiency was estimated to be 44 percent but with the implementation of the outlined general set of management proposals, the system efficiency was estimated to be increased to 62 percent. These management proposals result in an adequate water supply for all crop needs under the present cropland diversions, assuming adequate additional storage could be provided to redistribute the water to coincide with the demands. Under the present irrigation efficiency, the crop requirements are only being partially met.

It was estimated from the estimated future system efficiency, irrigation requirements, and the mean cropland diversions that water is available for export. The mean annual quantity of water available for export was estimated to be 630,000 acre feet. Most of this water is available for export during the non-growth months which requires large storage facilities at the points of useage. Further investigation is needed to determine the effect of this exportation on the ecology of the Great Salt Lake and the surrounding marsh lands.

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