Measurement of Hydraulic Conductivity Distributions: A Manual of Practice

摘要

The ability of hydrologists to perform field measurements of aquifer hydraulicproperties must be enhanced in order to significantly improve the capacity to solve ground water contamination problems at Superfund and other sites. The primary purpose of the manual is to provide new methodologies for measuring K(z), the distribution of horizontal hydraulic conductivity in the vertical direction in the vicinity of a test well. Measurements in nearby wells can then be used to estimate three-dimensional distributions. As dispersion-dominated models (particularly two-dimensional, vertically-averaged models) approach their limitations, it is becoming increasingly important to develop two-dimensional vertical profile or fully three-dimensional advection-dominated transport models in order to significantly increase the ability to understand and predict contaminant transport, reaction, and degradation in the field. Such models require the measurement of hydraulic conductivity distributions, K(z), rather than vertically averaged values in the form of transmissivities. Three devices for measuring K(z) distributions (the impeller flowmeter, the heat-pulse flowmeter, and a multi-level slug test apparatus) are described in detail, along with application and data reduction procedures. Results of the various methods are compared with each other and with the results of tracer studies. The flowmeter approach emerged as the best candidate for routine K(z) measurements. Impeller meters are now available commercially, and the more sensitive flowmeters (heat pulse and electromagnetic) are expected to be available in the near future.