GROUNDWATER FLOW MEASUREMENT IN UNCONSOLIDATED GLACIAL DEPOSITS USING FLUOROMETER ANALYSIS OF DISPERSED AND ADSORBED FLUORESCEIN DYE
This paper describes the development of a testing technique to determine groundwater flow direction and velocity in a single well. A series of experiments were performed using a device designed specifically to fit into a 152.4 mm (6 inch) diameter well casing. A test apparatus was assembled of polyvinyl chloride (PVC) pipes using porous stones to simulate groundwater flow conditions in an aquifer. The measurement device released fluorescein dye into the center of the simulated well using a dye release mechanism consisting of a glass vial with a salt plug suspended in modeling clay at its base. A small hole in exposed the top and bottom of the salt plug allowed the exchange of dye with the groundwater flowing past the dye outlet hole. The dye released into the well was subsequently adsorbed onto the surface of carbon rods located at eight equally spaced points around the perimeter of the well. The relative amount of the fluorescein dye remaining in the dye release vial, as well as the amount adsorbed on the carbon rods, was measured by the intensity of fluorescence detected by a fluorometer. The amount of the dye adsorbed onto the rods was shown to indicate the direction of groundwater flow with low directional dispersion. Groundwater flow velocity measurements were attempted using two methods. The first method correlated the fluorometer reading for the fluorescein dye/groundwater mixture remaining in the vial after a measured period of time with the flow velocity. The second method correlated the root-mean-square of the fluorometer readings for the fluorescein dye adsorbed onto and extracted from the carbon rods for an individual experiment with the groundwater flow velocity. The results of the first method's groundwater flow velocity experiments were a set of linear equations based on a multiple linear regression analysis relating discharge, measurement time, and fluorometer readings. The second method resulted in a linear relationship between the groundwater flow velocity and the root-mean-square of the carbon rod adsorption data. However, the groundwater flow velocity analysis using both methods showed poor correlation coefficients for the derived linear relationships. The suspect groundwater velocity measurements were attributed to the inconsistent nature of the dye release process and the inherent problems of introducing a dye tracer into a low Reynolds number laminar flow environment.
School:University of Cincinnati
School Location:USA - Ohio
Source Type:Master's Thesis
Keywords:groundwater flow direction and velocity measurement
Date of Publication:01/01/2002