One-dimensional soil water infiltration under water supply of negative hydraulic heads
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DOI:10.7606/j.issn.1000-7601.2007.05.24
Key Words: soil water  negative hydraulic head  infiltration  capillary rise  wetting front
Author NameAffiliation
XIE Ying-ge National Engineering Research Center for Information Technology in Agriculture, Beijing 100089,ChinaCollege of Science North wester A&F University,Yangling, Shaanxi 712100,China 
XUE Xu-zhang National Engineering Research Center for Information Technology in Agriculture, Beijing 100089,China 
WANG Guo-dong ;College of Science North wester A&F University,Yangling, Shaanxi 712100,China 
LI Xia ;College of Science North wester A&F University,Yangling, Shaanxi 712100,China 
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Abstract:
      Hydraulic head of supply water is maintained at negative values and vertical infiltration,capillary rise,and horizontal infiltration processes were observed.With increasing water supply tensions,relative differences of vertical infiltration,capillary rise,and horizontal infiltration processes in infiltration rates and wetting front movement speed decreased.The wetting depth at which infiltration rate is equal to potential evapo-transpiration rate is defined as critical wetting depth,and critical wetting depths at different negative hydraulic heads were obtained for the studied loamy soil by setting potential evapotransporation rate at 5 mm/d.Linear relationships between wetting depth and cumulative infiltration amount for vertical infiltration,capillary rise,and horizontal infiltration were validated.The slope of wetting depth-cumulative infiltration,i.e.,percentage of wetted soil volume occupied by infiltrated moisture,was defined as wetting coefficient,and the relationships between wetting coefficient and supply hydraulic head were provided for the studied loamy soil.A model describing soil moisture profile for vertical infiltration,capillary rise,and horizontal infiltration under negative supply hydraulic head was provided.The reliance of wetting front water content on supply hydraulic head was also demonstrated.