Determination of Unconfined Aquifer Characteristics

by George J. Kriz,

Serial Information: Journal of the Irrigation and Drainage Division, 1967, Vol. 93, Issue 2, Pg. 37-48

Document Type: Journal Paper


The various methods that have been proposed to solve the nonlinear differential equation for unsteady radial flow toward a well in an unconfined aquifer are divided into three categories. Each category is characterized by a particular assumption made on the h multiplier of the equation. A comparison is made as to the origin, characteristic assumption, and applicability in solving for the hydraulic conductivity and specific yield of an unconfined aquifer. The methods of Category I linearize the nonlinear differential equation and thus should be utilized for drawdown ratios of approximately 5%, or less. Adjustment of the field data or the confined aquifer type curve is characteristic of methods described in Category II. These methods should be restricted to drawdown ratios of 25%, or less. The reduction in flow thickness in the aquifer is directly taken into account by the method in Category III. Therefore, this method applies to all drawdown ratios of less than approximately 75%.

Subject Headings: Aquifers | Drawdown (hydrology) | Nonlinear analysis | Differential equations | Radial flow | Radiation | Unsteady flow | Comparative studies

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