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Analysis of Current Meter Data from Wells by Flow‐Distribution Curves a
Author(s) -
Leve Gilbert W.
Publication year - 1964
Publication title -
groundwater
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.84
H-Index - 94
eISSN - 1745-6584
pISSN - 0017-467X
DOI - 10.1111/j.1745-6584.1964.tb01751.x
Subject(s) - aquifer , geology , current (fluid) , artesian aquifer , current meter , flow (mathematics) , metre , hydrology (agriculture) , water well , marl , groundwater , petrology , geomorphology , geotechnical engineering , mechanics , structural basin , oceanography , physics , astronomy
Flow‐distribution curves, constructed from velocity graphs of current‐meter traverses, can be used to locate water‐bearing and nonwater‐bearing zones in an aquifer or in separate aquifers in a well and to determine the quantity of water entering between various depths. Current‐meter traverses in artesian wells in northeastern Florida show the applicability of flow‐distribution curves. The velocities recorded in the uncased portion of a well by a deep‐well current meter reflect either changes in the cross‐sectional area of the bore at the different depths or movement of different quantities of water through the well at these depths. Reasonably accurate measurements of the flow at certain depths in the uncased portion of a well can be determined by constructing flow distribution curves. These curves are constructed by utilizing points of maximum velocity, which are assumed to be levels having the minimum diameter of the well. Artesian wells in northeast Florida are generally cased to the top of the Floridan aquifer through 500 to 600 feet of clay, marl, and dolomite of Miocene to Recent age. The wells are completed open hole in the Floridan aquifer to depths of from 650 to 1,400 feet. Current‐meter traverses were run in four wells in the vicinity of Jacksonville. Flow‐distribution curves constructed from the velocity graphs indicate three separate water‐bearing zones occur in the aquifer. The first water‐bearing zone lies from about 600 to 800 feet below the land surface; the second, from 900 to 1,200 feet; and the third lies below 1,280 feet. These water‐bearing zones are separated by relatively impermeable non‐water‐bearing zones. Bar graphs constructed from the flow‐distribution curves show that the first water‐bearing zone yields from less than 10 to as much as 35 percent of the water; the second water‐bearing zone yields more than 50 percent of the water; and the third water‐bearing zone yields about 20 percent of the water with a penetration of only 50 to 70 feet. The flow‐distribution curves from current‐meter traverses made while there was no surface flow indicate internal leakage of less than 70 gallons per minute in wells 2 and 4 while the wells were not discharging at the surface. Leakage probably does not occur between these zones while the wells are discharging.