Soil water content and soil matric potential were monitored during 2 years at two neighboring ridge-top sites in an oak-hickory stand on a Typic Paleudult forest soil with cherty silt loam texture. Hydraulic gradients and soil water contents showed distinct seasonal variation. Soil water dynamics and water budgets were simulated with a soil-plant-atmosphere water flow model using meteorologic, soil, and plant characteristics estimated for the two sites. A seasonal pattern of soil water drainage and upward fluxes was predicted by the model that corresponded with the field-determined hydraulic gradients. Recharge of water up into the root zone (0- to 90-cm depth) from lower depths was predicted to contribute an average of 9 and 29% of the soil evaporation plus transpiration water loss at the two sites. Total evapotranspiration, including interception evaporation, was similar at the two sites; however, the greater upward water flux at one site compensated for the lower soil water capacity in the root zone at that site. There were significant differences between calculated and simulated daily drainage rates. Simulated soil water contents for the two study sites differed somewhat from measured values obtained on specific days. At longer time scales, the annual water budgets simulated for the sites were similar and were in reasonable agreement with measurements from a local watershed study. Annual evapotranspiration was predicted to be 74.5 cm for the ridge-top forest stand, somewhat higher than the average of 70.5 cm estimated for the whole watershed.
