Volumetric water content

Figure 13 Volumetric water contents for Haw series soil calculated using the Penman equation...

Figure 14 Comparison of actual volumetric water contents (measured by time domain reflectom-etry) and calculated soil-water flux values (Penman equation) at four soil depths...

More sophisticated methods that actually measure volumetric water content can also be used, such as time domain reflectometry (TDR). In Figure 14, an example of TDR results is presented. Both the calculated and measured (i.e., TDR) volumetric water contents provide a similar picture of the profile water status by depth with time. Proper soil characterization data, such as those shown in Table 6, are necessary for these calculations and improve understanding of the test system. The determination of water-holding capacity (WHC) at 0.03 MPa field capacity (FC) and 1.5 MPa... 

Table 7 Measured and estimated volumetric water contents as a function of depth and matrix potential for a Haw series soil (Payette Country, Idaho)...

FIGURE 3.25 Graphs of hydraulic conductivity vs. volumetric water content showing characteristic curves for different sediments from the VOC-arid site integrated demonstration at the Hanford site. 

In this chapter, we examine the various mechanisms that influence chemical redistribution in the subsurface and the means to quantify these mechanisms. The same basic principles can be applied to both saturated and partially saturated porous media in the latter case, the volumetric water content (and, if relevant, volatilization of NAPL constiments into the air phase) must be taken into account. Also, such treatments must assume that the partially saturated zone is subject to an equilibrium (steady-state) flow pattern otherwise, for example, under periods of heavy infiltration, the volumetric water content is both highly space and time dependent. When dealing with contaminant transport associated with unstable water infiltration processes, other quantification methods (e.g., using network... 

In partially saturated media, the diffusion coefficient also is a function of the volumetric water content, 9. Calvet (1984) showed that the variation in soil water content influences the apparent diffusion coefficient for organic contaminants in two ways by changing the ratio of gas diffusion of volatilizable pollutants to liquid diffusion, because the air-filled porosity is affected, and by modifying pollutant... 

Volumetric water content is the fraction of the soil pores that are filled with water. 

Electromagnetic parameters are sensitive to the properties of soils, including volumetric water content/porosity, specific surface, ionic concentration, anisotropy, and temperature. The general trends are summarized in Table 1. Table 2 presents selected models relating the electromagnetic parameters to mixture properties. 

K1 volumetric water content 0V process monitoring (cement hydration) k I as 0V4 (f T GHz)... 

Notation o=e1ectrical conductivity, ic-real relative permittivity, subscripts mix, f and p denote soil-flu id mixture, fluid, and particle, respectively, /-ionic valence, c-ionic concentration, u=ionic mobility is, F =96485.3 C/mol is Faraday s constant, TDS= total dissolved salts in [mg. L], n=porosity, p=density, =surface conduction, S,=specific surface, a=degree of saturation, m=cementation factor, Gv=volumetric water content... 

V) % water-filled pore space = volumetric water content = 39%... 

In topsoils, the development of redox zones is directly related to the soil volumetric water content (cm of water per cm ), as this determines the composition and activity of soil biota (Eenchel et al., 1998). Water potential is affected by both solute and matrix characteristics, which subsequently affect the ecophysio-logy of microorganisms. The soil biota which... 

WS = volumetric water content in vadose zone soils (cm3/cm3)... 

Subtract the value of volumetric water content finm the value of total porosity to get the value of air-filled porosity... 

Determine the water content of that layer of soil gravimetrically and convert to volumetric water content by multipl3dng it with bulk density of the soil. 

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