In this presentation, the water vapor exchanges between the surface and the atmospheric boundary layer over a complex heterogeneous landscape are examined. The water vapor turbulent flux is observed at the Howard University Beltsville site (39.054° latitude; -76.877° longitude) in an open area covered by grass and surrounded by trees. The site is in close proximity to urban and industrial zones which make it suitable for flux computations over a rural-urban landscape. The Howard University Beltsville site includes a 30-meter flux tower, fully instrumented with meteorological sensors including three-dimensional sonic anemometers and trace gas analyzers. The purpose of this study is to establish continuous and high quality water vapor flux datasets at the site, and to investigate the processes governing water vapor transfer within the lower layers of the atmospheric boundary layer during the forest defoliation period. The water vapor fluxes are also employed to assess the fidelity of the water vapor exchanges treatment in the Weather Research and Forecasting mesoscale model.