Hydraulic Conductivity - Amoozemeter

Parameter to be measured:

Hydraulic conductivity

Method:

Constant head permeameter: Measures infiltration rate within an auger hole up to a depth of 2 m and with extension set up to a depth of 4 m. A constant hydraulic head is kept in the auger hole which must be H/r >= 5 and the infiltration rate will be monitored until steady state flow is attained. Hydraulic conductivity will be calculated with the equation of Glover (Amoozegar, 1989b, 1993)

Advantages:

• in-situ measurement, no analysis of disturbed soil samples in lab
• measurement in different depths of soil profile
• easily transportable for monitoring at any location
• less water consume

Disadvantages:

• many pipes and valves - requires practice and understanding to recognise errors, set-up time
• price
• exact geometry of auger hole as specified in the equation is not often realised
• in depth up to 70 cm the measurment is complicated because of controling water level
• soils with high content of gravels and boulders would be problematic because of realsing the correct geometry of the auger hole

What to watch out for:

potential problems with

• hydrophobic soils
• heterogenous water content of soil before measurement
• strong effects from preferential flowpaths
• strong swelling/shrinking of soil
• effects of impermeable layers before stationarity is achieved
• inclined, uneven surfaces
• in loamy and clay soils the augering will smear up the soil pores which will lead to an underestimation of hydraulic conductivity

Links

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Other related web sites:

References

Amoozegar, A, 1989a. A compact, constant-head permeameter for measuring saturated hydraulic conductivity of the vadose zone, Soil Sci. Soc. Am. J., 53, 1356–1361.

Amoozegar, A, 1989b. Comparison of the Glover solution with the simultaneous equations approach for measuring hydraulic onductivity, Soil Sci. Soc. Am. J., 53, 1362–1367.

Amoozegar, A, 1993. Comments on ‘‘Methods for analyzing constanthead well permeameter data’’, Soil Sci. Soc. Am. J., 57, 559– 560. Elrick, DE, Reynolds WD, 1992. Methods for analyzing constanthead well permeameter data, Soil Sci. Soc. Am. J., 56, 320– 323.

Elrick, DE, Reynolds, WD, 1992. Methods for analyzing constanthead well permeameter data, Soil Sci. Soc. Am. J., 56, 320– 323.

Elsenbeer, H, Newton, BE, Dunne T, de MoraesJM, 1999. Soil hydraulic conductivities of latosols under pasture, forest and teak in Rondonia, Brazil. Hydrol. Process. 13, 1417-1422.

Sobieraj, JA, Elsenbeer, H, Coelho, RM, Newton, B, 2002, Spatial variability of soil hydraulic conductivity along a ropical rainforest catena, Geoderma, 108, 79–90.