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RESEARCH PRODUCT

Saturated Soil Hydraulic Conductivity

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description

This chapter deals primarily with field measurement of saturated soil hydraulic conductivity, K fs . Well or borehole permeameter techniques, specifically developed for subsurface soil measurements above the water table, are initially illustrated. Particular attention is paid to establishment of steady flow under constant head in an uncased borehole, widely developed both theoretically and experimentally in the last 30 years. Situations involving cased boreholes, transient flow, or falling head processes are then described. These variants have received a renewed interest in the last few years. New data analysis procedures have been proposed and this circumstance allows us to obtain subsurface K fs data in a variety of conditions. Ring infiltrometers, mostly usable for surface soil sampling, are illustrated, starting from the largely applied single-ring pressure infiltrometer. Other single-ring methods are then described. They include methods that rely on the Beerkan experimental protocol and consider the transient phase of an infiltration process under a constant and practically null pressure head on the soil surface and methods involving falling head infiltration runs. The classical double-ring infiltrometer is subsequently described. Then, the simplified falling head technique, using small volumes of water to establish a one-dimensional infiltration process, is illustrated. Finally, the dripper or point-source method, usable to measure K fs at the soil surface without inserting a ring into the porous medium, is described. Seven examples show how to analyse the field data collected in particular experimental situations.