Peat Hydraulic Conductivity Research Articles

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

AbstractSubsurface 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.

Hydraulic conductivity of peat at Ellergower Moss, Scotland

AbstractFalling head (and a few rising head) measurements were made of hydraulic conductivity k in a profile of a 7 m deep, small raised bog in southwest Scotland. The seven piezometer pipes were 39 mm diameter, and most of the measurements were made with attached tubes of 2·5 mm diameter, so that only 2–3 mm of water crossed the peat interface during a run. There were no consistent effects of pre‐flushing, direction of flow (falling, rising), or measuring‐tube size. Variability of 10–20% in k did not obscure an exponential decrease with depth from 5 × 10−6 cm s−1 at 100 cm to 0·7 × 10−6 cm s−1 at 500 cm. This decrease was uncorrelated with dry bulk density or peat stiffness, and only loosely so with a measure of humification. Calculated mean bulk velocity of pore water may be as low as 1 mm year−1. Pressure in the silty sand below the peat was 180 mbar less than expected, suggesting a thin highly impermeable layer (‘pan’?) at the peat base. The substratum may have hydrological connection with an adjacent lake. The hydraulic properties of this raised bog contrast strongly with those of a raised bog in Minnesota, and do not fit the assumptions made for Ingram's simple groundwater mound model of raised bog shape. Copyright © 2004 John Wiley & Sons, Ltd.

Studies on the hydraulic conductivity of peat : Korpijaakko, M J Ph D thesis, New Brunswick Univ, 1975

Studies on the hydraulic conductivity of peat : Korpijaakko, M J Ph D thesis, New Brunswick Univ, 1975