Determination of coefficient of storage by use of gravity measurements.
type: CreativeWork
description: The purpose of the study was to develop a method to determine the coefficient of storage of a water-table aquifer by correlating change in gravitational field intensity with change in groundwater storage. In theory, this purpose may be accomplished by modifying the Bouguer slab equation to coefficient of storage equals 78.3 times the ratio of change in gravity in milligals to change in water-table elevation in feet. Errors which result from the Bouguer slab assumptions may be corrected through analysis of tilted finite slabs. Field investigations were made to test the theory. The study area is located in the northern Tucson basin, Pima County, Arizona, and lies on unconfined basin-fill deposits and flood-plain alluvium aquifers. The basin-fill aquifer overlies less permeable Rillito beds and is overlain by the flood-plain alluvium. The two upper aquifers are flat-bedded heterogeneous deposits of sand and gravel. The water table through these aquifers slopes westward at a rate of approximately 0.5 degree. Estimates of the coefficient of storage for the basin-fill deposits and the flood-plain alluvium have been previously made by others from laboratory and field tests and by model analyses. The most reliable determinations of the coefficient of storage range from 0.15. to 0.30. The significance of the gravity method lies in determination of the coefficient of storage by measuring the quantities which define it: rise or decline in head and weight of water placed into or removed from storage. Change in gravity was determined by repeated gravity surveys using the same set of field stations through the period, October 1968 to June 1970. Water levels in wells were recorded for the same period. The relationship between change in gravitational field intensity and change in head was determined using a straight line solution method, and the coefficient of storage was computed from the slope of the straight line. At the conclusion of the field investigations, coefficients of st…
abstract: The purpose of the study was to develop a method to determine the coefficient of storage of a water-table aquifer by correlating change in gravitational field intensity with change in groundwater storage. In theory, this purpose may be accomplished by modifying the Bouguer slab equation to coefficient of storage equals 78.3 times the ratio of change in gravity in milligals to change in water-table elevation in feet. Errors which result from the Bouguer slab assumptions may be corrected through analysis of tilted finite slabs. Field investigations were made to test the theory. The study area is located in the northern Tucson basin, Pima County, Arizona, and lies on unconfined basin-fill deposits and flood-plain alluvium aquifers. The basin-fill aquifer overlies less permeable Rillito beds and is overlain by the flood-plain alluvium. The two upper aquifers are flat-bedded heterogeneous deposits of sand and gravel. The water table through these aquifers slopes westward at a rate of approximately 0.5 degree. Estimates of the coefficient of storage for the basin-fill deposits and the flood-plain alluvium have been previously made by others from laboratory and field tests and by model analyses. The most reliable determinations of the coefficient of storage range from 0.15. to 0.30. The significance of the gravity method lies in determination of the coefficient of storage by measuring the quantities which define it: rise or decline in head and weight of water placed into or removed from storage. Change in gravity was determined by repeated gravity surveys using the same set of field stations through the period, October 1968 to June 1970. Water levels in wells were recorded for the same period. The relationship between change in gravitational field intensity and change in head was determined using a straight line solution method, and the coefficient of storage was computed from the slope of the straight line. At the conclusion of the field investigations, coefficients of st…
author: Montgomery, Errol Lee,1939-
language: en
keywords: Hydrology., Groundwater -- Arizona.
date published: 1971
date modified: 2026-07-24T00:55:47Z
provider: University of Arizona
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: The University of Arizona.

PropertyValue
property ID: Handle
value: http://hdl.handle.net/10150/190978