HR: 17:05h
AN: H22J-05    [PDF]
TI: Horizontal Fluid Infiltration: A New Measurement Device and Some Observations
AU: * Culligan, P J
EM: culligan@civil.columbia.edu
AF: Columbia University, Department of Civil Engineering and Engineering Mec hanics 610 S.W. Mudd Building, New York, NY 10027 United States
AU: Ivanov, V M
EM: vmivanov@yahoo.com
AF: Massachusetts Institute of Technology, Department of Civil and Environmental Engineering Room 1-353, Cambridge, MA 02139 United States
AU: Germiane, J T
EM: jgermain@mit.edu
AF: Massachusetts Institute of Technology, Department of Civil and Environmental Engineering Room 1-353, Cambridge, MA 02139 United States
AB: Fluid infiltration in the vadose zone has been the subject of study since the early 1900s. Understanding infiltration processes is important to numerous problems, including forecasting moisture distribution following soil irrigation, estimating the potential for leachate generation during landfill cover design, and predicting contaminant transport to groundwater following a surface spill. Many models have been developed to describe fluid infiltration, including the well-known models by Jean-Yves Parlange and his co-workers (e.g., Smith and Parlange, Water Resources Research, 14(3), 1978). These models predict the time-rate of infiltration and the cumulative volume of infiltration based on parameters, such as sorptivity, that are often obtained from laboratory experiments. The proper design of these experiments, and appreciation of the factors controlling parameters derived from them, is therefore key to the accuracy of such models. This paper describes a new experimental setup to observe fluid infiltration under one-dimensional capillary dominated flow. Dry soil is packed in a horizontal 700 mm long polycarbonate channel that is 25.5 mm x 25.5 mm in cross-section. The top of the channel is open to the atmosphere. The upstream end of the channel is connected, via a three-valve chamber, to an infiltrant container placed on an electronic balance. Initial flooding and final draining of the three-valve chamber can be controlled without disturbing conditions in the column. The height of the infiltrant container can be adjusted to control the fluid inlet head. The end of the column is capped with a seal that allows the free exit of air. During an experiment, fluid is introduced at the upstream end of the column at a fixed head. The position of the infiltration front and the cumulative mass of fluid flowing into the column are both observed with time. At the end of each experiment, the fluid saturation along the column is obtained by sampling from the top, open surface of the column. Infiltration experiments into initially dry, uniform sand (D10 = 0.09 mm) were performed using the new setup. Either water or Soltrol 220 was used as the infiltrant. The inlet head was varied between -30 cm and 50 cm. For all experiments, a linear increase in fluid infiltration with the square root of time was observed, confirming capillary dominated flow. Results from the experiments demonstrate that the sorptivity and transmission zone saturation both increase with the infiltrant head. The results also reveal that the sorptivity of water and soltrol in a soil cannot be simply related through the fluid properties, even when the infiltrant head is zero. Both of these findings have implications for the measurement and use of sorptivity (or other related parameters) for predicting fluid infiltration.
DE: 1829 Groundwater hydrology
DE: 1866 Soil moisture
DE: 1875 Unsaturated zone
SC: Hydrology [H]
MN: 2003 Fall Meeting