This data set reports monthly measured soil volumetric water content (VWC) from a rainfall exclusion experiment that was conducted from 1999-2001 at the km 67 Seca Floresta site, Tapajos National Forest, Brazil. The purpose was to observe the potential effects of severe water stress on a humid Amazonian forest (Nepstad 2002). There are two ASCII comma delimited files with measured VWC, one for the ... control plot and one for the rainfall exclusion plot. These measured values were used by the authors to develop a model of daily changes in the distribution of water through the soil layers. The simulated daily VWC values are also provided in the file with the measured VWC. For comparison, results of VWC simulation for the control and treatment plots using a STELLA model which incorporates rainfall and plant water uptake are provided. There are two ASCII comma delimited files of simulated results. See Belk et. al., 2007 for details.