Estimating Macroporosity in a Forest Watershed by use of a Tension Infiltrometer1
- K. W. Watson and
- R. J. Luxmoore2
The ability to obtain sufficient field hydrologic data at reasonable cost can be an important limiting factor in applying transport models. A procedure is described for using ponded-flow- and tension-infiltration measurements to calculate transport parameters in a forest watershed. Thirty infiltration measurements were taken under ponded-flow conditions and at 3, 6, and 15 cm (H2O) tension. It was assumed from capillarity theory that pores >0.1-, 0.05-, and 0.02-cm diam, respectively, were excluded from the transport process during the tension infiltration measurements. Under ponded flow, 73% of the flux was conducted through macropores (i.e., pores >0.1-cm diam.). An estimated 96% of the water flux was transmitted through only 0.32% of the soil volume. In general the larger the total water flux the larger the macropore contribution to total water flux. The Shapiro-Wilk normality test indicated that water flux through both matrix pore space and macropores was log-normally distributed in space.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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