Peat hydraulic conductivity in cold regions and its relation to pore size and geometry

Subsurface flow through peat plays a critical role in the hydrology of organic-covered, permafrost terrains, which occupy a large part the continental arctic, sub-arctic, and boreal regions. Hillslope drainage in these terrains occurs predominantly through the active flow zone between the relatively impermeable frost table and the water table above it. The hydraulic conductivity profile within this zone controls the subsurface drainage of snowmelt and storm water. Peat hydraulic conductivity profiles were examined at three sites in north-western Canada, each representing a widely occurring organic-covered, permafrost terrain type. Three independent measures of saturated hydraulic conductivity were used—tracer tests, constant-head well-permeameter tests, and laboratory measurements of undisturbed samples. At all three sites, the conductivity profiles contained very high values (10–1000 m d−1) within the top ca 0·1 m where the peat is only lightly decomposed, a large reduction with increasing depth below the ground surface in the transition zone, and relatively low values in a narrow range (0·5–5 m d−1) below ca 0·2 m depth, where the peat is in an advanced state of decomposition. Digital image analysis of resin-impregnated peat samples showed that hydraulic conductivity is essentially controlled by pore hydraulic radius. The strong dependence of hydraulic conductivity on hydraulic radius implies that peat soils subjected to similar degrees of decomposition and compaction have a similar hydraulic conductivity regardless of the location. This explains the similarity of the depth-conductivity profiles among all three terrain types. Copyright © 2008 John Wiley & Sons, Ltd.

[1]  W. J. Langford.  Statistical Methods , 1959, Nature.

[2]  W. Quinton,et al.  THE FLOW AND STORAGE OF WATER IN THE WETLAND-DOMINATED CENTRAL MACKENZIE RIVER BASIN : RECENT ADVANCES AND FUTURE DIRECTIONS , 2005 .

[3]  John R. Clark,et al.  Wetland Functions and Values: The State of Our Understanding , 1981 .

[4]  W. Quinton,et al.  A constant-head well permeameter method for measuring field-saturated hydraulic conductivity above an impermeable layer , 2004 .

[5]  James G. Berryman,et al.  Using two‐point correlation functions to characterize microgeometry and estimate permeabilities of sandstones and porous glass , 1996 .

[6]  N. Matveyeva,et al.  4 – Circumpolar Arctic Vegetation , 1992 .

[7]  W. J. DeCoursey,et al.  Introduction: Probability and Statistics , 2003 .

[8]  J. Price,et al.  The effects of matrix diffusion on solute transport and retardation in undisturbed peat in laboratory columns , 1997 .

[9]  J. Price,et al.  A field-scale, natural gradient solute transport experiment in peat at a Newfoundland blanket bog , 1995 .

[10]  William L. Quinton,et al.  Snowmelt Runoff from Northern Alpine Tundra Hillslopes: Major Processes and Methods of Simulation , 2004 .

[11]  J. Apruzese,et al.  Functional dependencies of the Cu XXVIII line power output coincident with a nuclear transition in 169Tm , 1988 .

[12]  W. Quinton,et al.  Subsurface Drainage from Organic Soils in Permafrost Terrain : The Major Factors to be Represented in a Runoff Model , 2002 .

[13]  A. Heathwaite,et al.  Anisotropy and depth‐related heterogeneity of hydraulic conductivity in a bog peat. I: laboratory measurements , 2003 .

[14]  J. Bear.  Dynamics of Fluids in Porous Media , 1975 .

[15]  E. M. Schlueter,et al.  The fractal dimension of pores in sedimentary rocks and its influence on permeability , 1997 .

[16]  T. Mukerji,et al.  The Rock Physics Handbook , 1998 .

[17]  W. D. Carrier.  Goodbye, Hazen; Hello, Kozeny-Carman , 2003 .

[18]  P. Marsh,et al.  Image analysis and water tracing methods for examining runoff pathways, soil properties and residence times in the continuous permafrost zone , 1999 .

[19]  M. Schaap,et al.  Using microscope observations of thin sections to estimate soil permeability with the Kozeny–Carman equation , 2001 .

[20]  C. Kessel,et al.  Construction and evaluation of a reference electrode assembly for use in monitoring in situ soil redox potentials , 1991 .

[21]  D. Gray,et al.  Subsurface drainage from hummock-covered hillslopes in the Arctic tundra , 2000 .

[22]  Robert W. Zimmerman,et al.  Predicting the permeability of sandstone from image analysis of pore structure , 2002 .

[23]  Victor S. Kennedy,et al.  Wetland functions and values: The state of our understanding , 1981 .

[24]  James G. Berryman,et al.  Kozeny–Carman relations and image processing methods for estimating Darcy’s constant , 1987 .