The determination of the drainage factor as a criterion for the soils of the Indos Plains.

Abstract

Drainage factors (DF) were used as design criteria for comparing relative costs of horizontal and tubewell drainage of mainly medium-textured silty loams, especially in saline groundwater areas. DF calculated from recharge estimates were higher than those calculated from leaching requirements. For tubewell drainage (normally maintaining a water-table lower than is possible with horizontal drainage) DF from recharge estimates should serve as criteria for establishing the capacity of the installation. For calculating the required spacing for horizontal drainage, DF slightly higher than those derived from leaching requirements are desirable to take into account drainage or seepage from line sources. If wide spacings are calculated with relatively small DF, the reaction of the water-table halfway between the drains to intermittent recharge may be too slow, and a smaller spacing may be required. Because of limited accuracy of the DF, additional data on hydraulic conductivity of the soil are desirable. (Abstract retrieved from CAB Abstracts by CABI’s permission)