ABSTRACT
The tension or disk infiltrometer is used primarily for field (in situ) measurement of nearsaturated hydraulic conductivity, K(c) [LT1], and sorptivity, S(c) [LT1=2]. It can also be used, however, to determine near-saturated sorptive number, a*(c) [L1], flow-weighted mean pore diameter, PD(c) [L], and number of flow-weighted mean pores per unit area, NP(c) [L2]. By ‘‘near-saturated’’ we mean measurements at pore water matric heads (c) within the range, 20 cm c þ2 cm, although some infiltrometers can operate at matric heads as low as 40 cm. An alternative field method for K(c) determination in the ‘‘wet-end’’ (i.e., 200 cm c 0) is given in Chapter 83. Laboratory methods for K(c) or K(u) determination are given in Chapter 80 and Chapter 81. Selected methods for estimating K(c) from surrogate porous medium properties are given in Chapter 84. A discussion of the principles and parameters associated with the determination of K(c) and the capillarity relationships [i.e., S(c), a*(c), PD(c), NP(c)] appears in Chapter 69. Given that flow from field-based tension infiltrometers is three dimensional, the measured K(c) and capillarity relationships are most relevant to three-dimensional flow.
