International Water Management Institute, Colombo
DOI:
https://doi.org/10.52151/jae2009462.1376Abstract
The flow dynamics of auger hole method, used for hydraulic conductivity measurements, was examined with the help of streamlines. Values of stream function around an auger hole penetrating to an impervious layer were calculated for different depths of pumped water level in the hole. Streamlines were drawn around an auger hole for four cases of pumped water level- auger hole empty, one-fourth full, half full and threefourth full. Examination of streamlines highlighted the consequence of change in pumped water level on flow toward the auger hole. Contrary to the earlier belief that auger hole measurements give average horizontal saturated hydraulic conductivity of the soil zone from static water table level to the bottom of the auger hole, it is shown that this is true only in case of uniform isotropic soils. It is suggested that the auger hole tests for subsurface drainage design must be conducted with very small amount of pumping (say 25 %) so that the soil region and flow direction used for measurement of saturated hydraulic conductivity adequately represent the soil and flow direction in the actual system. It was also observed that the measured value of saturated hydraulic conductivity, particularly for a soil with variable conductivity with depth, would be more representative of the average if measurements are taken with small depth of water pumped from the hole.
Downloads
References
Boast C W; Kirkham D. 1971. Auger hole seepage theory. Soil Sci. Soc. Amer. Proc., 35, 365-373.
Bouwer H; Rice R C. 1983. The pit bailing method for hydraulic conductivity measurements of isotropic or anisotropic soil. Trans. ASAE, 26, 1435-1439.
Childs E C; Cole A H; Edwards, D H. 1953. The measurement of the hydraulic permeability of saturated soils in situ. II. Roy. Soc. (London), Proc., A 216, 72-89.
Ernst L F. 1950. A new formula for the calculation of the permeability factor with the auger hole method. T.N.O. Groningen 1950. Translated from the Dutch by H. Bouwer, Cornell Univ. Ithaca, New York, 1955.
Fogg E F; Senger R K. 1985. Automatic generation of flow nets with conventional ground-water modelling algorithms. Ground Water, 23(3), 336-344.
Hooghoudt S B. 1940. Bepaling van den doorlaatfacyor van den ground met behulp van pompproeven, (z.g. boorgaten methode). Verslag Landbouwk. Onderzoek, 42, 449-541.
Johnson H P; Frevert R K; Evans D D. 1952. Simplified procedure for the measurement and computation of soil permeability below the water table. Agril. Engg., 33, 283-286.
Kessler J; Oosterbaan R J. 1974. Determining hydraulic conductivity of soils. In Drainage Principles and Applications. ILRI, Wageningen, The Netherlands, 3(16), 253-296.
Kirkham D. 1946. Proposed method for field measurement of permeability of soil below the water table. Soil Sci. Soc. Amer. Proc., 10, 58-68.
Kirkham D; van Bavel C H M. 1948. Theory of seepage into auger holes. Soil Sci. Soc. Amer. Proc., 13, 75-83.
Luthin J N; Kirkham D. 1949. A piezometer method for measuring permeability of soil in situ below a water table. Soil Sci., 68, 349-358.
Olver F W J. 1965. Bessel functions of integer order. In: Milton Abramowitz and Irene A.Stegun (Editors), Handbook of Mathematical Functions, Dover Publications, Inc., New York, 355-433.
Rogers J S. 1986. Finite element model of flow to an auger hole in layered soils. Trans ASAE, 29(4), 1005-1011.
Rogers J S; Carter C E. 1987. Auger hole hydraulic conductivity determination in layered soils. Trans ASAE, 30(2), 374-378.
Snell A W; van Schilfgaarde J. 1964. Four well method of measuring hydraulic conductivity in saturated soils. Trans ASAE, 7, 83-87, 91.
USDI. 1978. Drainage Manual. Oxford and IBH Publishing Company, New Delhi, pp. 286.
Zaslavsky D; Kirkham D. 1964. The streamline function for axially symmetric groundwater movement. Soil Sci. Soc. Amer. Proc., 28, 156-160.
