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THEORY OF TIME RESPONSE OF TENSIOMETERS
Author(s) -
TOWNER G. D.
Publication year - 1980
Publication title -
journal of soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.244
H-Index - 111
eISSN - 1365-2389
pISSN - 0022-4588
DOI - 10.1111/j.1365-2389.1980.tb02108.x
Subject(s) - tensiometer (surface tension) , hydraulic conductivity , geotechnical engineering , water potential , soil water , soil science , environmental science , engineering , thermodynamics , physics , surface tension
Summary The time taken for a tensiometer to reach equilibrium with the soil‐water pressure is a function not only of the tensiometer characteristics but also of the soil‐water transport properties. When. in an appropriate system of units. the numerical value of the conductance of the tensiometer cup is small compared with that of the hydraulic conductivity of the soil, and the sensitivity of the pressure ‘gauge’ is large compared with the differential water capacity of the soil. then the precision of the measurements is such that the observed response may be indistinguishable from that of a tensiometer in bulk water. referred to as ‘tensiometer limited’. The theory developed in this paper for a hemispherical tensiometer cup shows that tensiometer‐limited conditions can be achieved in practice. Moreover. such conditions would often correspond to a rapid response system. It is suggested that it might be advantageous in the design of a field recording system to choose a tensiometer‐limited system even if it is not the fastest realisable one in order that its response is completely predictable from the known tensiometer characteristics. independent of the unknown soil properties. which may be changing.