Document Type

Thesis - Open Access

Award Date

1960

Degree Name

Master of Science (MS)

Department

Agricultural Engineering

Abstract

The physical property of soil which enables it to pass or conduct water through its macro-pores is known as its permeability. Permeability should not be confused with infiltration, which is the term for expressing the absorption of water into the soil. The infiltration rate is the rate at which water will enter the soil surface. The rate at which water moves through soil is called the hydraulic conductivity; whereas a measurement of this same rate is used to calculate the permeability. Hydraulic conductivity is most commonly expressed in the units of velocity, whereas permeability is expressed as the square of some unit of length, or 〖(L)〗^2. The specific need for hydraulic conductivity and permeability measurements is to determine the rate at which water will move through soil. The design of most subsurface drainage is based on hydraulic conductivity and permeability measurements. This study will deal primarily with the measurement of soil permeability and conductivity as a function of the drainability of agricultural lands. As the food requirements of a growing population increases, drainage will be one of the principle tools to help increase food production. The most fertile, and potentially productive agricultural land is located on bottom lands along rivers and streams. The hindrances preventing it from being out to maximum productive use are the presence of a high fluctuating water table and periodic surface flooding. Both of these can be controlled or minimized by the installation of properly designed drainage and water control measures. Subsoil drainage of agricultural land is accomplished by two principle methods - interceptor drains and collector systems. The interceptor drain is an underground tile line placed perpendicular to the direction of the horizontal movement of water through the soil. It collects or intercepts the water, thereby lowering the water table on the down-slope side of the tile line. Its effectiveness is limited to the more arid regions where there is a minimum of water table recharge from the surface directly above the affected area. Collector drains are commonly designed in a geometric pattern. The lines are generally parallel and drain to a common outlet. They are most commonly used in areas where the ground water build-up or recharge is primarily from surface infiltration. There is also a particular need for drainage in areas where irrigation is being practiced and no natural drainage exists. It is also needed for certain area s that are being contemplated for irrigation development. Past experiences indicate the adequate drainage is necessary for successful irrigation. Any development and expansion of irrigation in some of the new areas proposed for irrigation is going to depend considerably on the economics of providing the drainage system along with the water distribution system. It has been recognized that the development of the James Basin or Lake Plain area for successful irrigation will require constructed drains to control the rise of the water table. Considerable investigative work has already been conducted by the U.S. Bureau of Reclamation on this proposed project. Three methods of measuring the permeability or hydraulic conductivity were employed by the Bureau. Field laboratory permeability measurements were made on disturbed samples and undisturbed core samples. Relatively small samples were used for both of these methods. The third method obtained hydraulic conductivity measurements in the files using the ring infiltrometer. A brief description of each procedure is included in Appendix D. The objective of this study is to devise a method or procedure which may be used to obtain these measurements.

Library of Congress Subject Headings

Drainage
Permeability

Description

Includes bibliographical references

Format

application/pdf

Number of Pages

77

Publisher

South Dakota State University

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