TY - JOUR
T1 - On the Structure and Flow Processes in the Capillary Fringe of Phreatic Aquifers
AU - Ronen, Daniel
AU - Scher, Harvey
AU - Blunt, Martin
N1 - Funding Information:
The authors thank the generosity of the Feldman Foundation and the Faivovich Foundation for Grants that have contributed to their on-going research activities in the interface region of granular sediments. H.S. is grateful for support from the Sussman Family Center for the Study of Environmental Sciences.
PY - 1997/1/1
Y1 - 1997/1/1
N2 - The water distribution in the capillary fringe (CF) reflects the interaction of a strongly wetting fluid in a heterogeneous porous medium. Field profiles of gravimetric water content of the CF for a 30 m deep, sandy, phreatic aquifer in Israel are critically analyzed in the context of the possible wetting and drainage processes in these sediments. A highly plausible explanation of the profiles is based on the spatial configuration of the CF surface determined from a model of the movement of water within the porous medium. The structural types of CF that can arise from a number of competing pore-scale displacement mechanisms, in the presence of gravity, are characterized by the model. We differentiate between two generic types of CF structures: a tenuous invasion-percolation type and a compact type. Flow, in response to a horizontal pressure gradient, associated with each structure is analyzed. Our interpretation of the field data supports the compact structure with a spatial variation in the height of the CF surface, above the water table, on the order of 1 m. In this compact structure horizontal flow is characterized by stagnant regions in the CF above a critical height hc and flow only for regions below hc. The field water content (at hc) may be used to predict the onset of lateral water flow in the CF.
AB - The water distribution in the capillary fringe (CF) reflects the interaction of a strongly wetting fluid in a heterogeneous porous medium. Field profiles of gravimetric water content of the CF for a 30 m deep, sandy, phreatic aquifer in Israel are critically analyzed in the context of the possible wetting and drainage processes in these sediments. A highly plausible explanation of the profiles is based on the spatial configuration of the CF surface determined from a model of the movement of water within the porous medium. The structural types of CF that can arise from a number of competing pore-scale displacement mechanisms, in the presence of gravity, are characterized by the model. We differentiate between two generic types of CF structures: a tenuous invasion-percolation type and a compact type. Flow, in response to a horizontal pressure gradient, associated with each structure is analyzed. Our interpretation of the field data supports the compact structure with a spatial variation in the height of the CF surface, above the water table, on the order of 1 m. In this compact structure horizontal flow is characterized by stagnant regions in the CF above a critical height hc and flow only for regions below hc. The field water content (at hc) may be used to predict the onset of lateral water flow in the CF.
KW - Capillary fringe
KW - Multiphase flow
KW - Network modeling
KW - Saturated-unsaturated interface
UR - http://www.scopus.com/inward/record.url?scp=0031200956&partnerID=8YFLogxK
U2 - 10.1023/A:1006583410617
DO - 10.1023/A:1006583410617
M3 - Article
AN - SCOPUS:0031200956
SN - 0169-3913
VL - 28
SP - 159
EP - 180
JO - Transport in Porous Media
JF - Transport in Porous Media
IS - 2
ER -