Hydropedological Function at a Long Term Waste Treatment Site.

A methodology for continuous water balance accounting at the pedon scale derived from point soil moisture measurements, including vertical water fluxes, preferential flow and evapotranspiration, would be of great use to both the agricultural and scientific communities.  Vertical water velocity is a critical control of contaminant transport, water balance calculations, and applications of irrigation and fertilizer.  The controls on preferential flow, which is thought to be the rule rather than the exception in many soils, remains poorly understood, and is a key mechanism for groundwater and stream contamination from agricultural sites.  Evapotranspiration is a key indicator and control on the health and growth of both cropped and natural systems.  A synthetic understanding of these factors would lead to an understanding of water stores and fluxes in the soil, aiding agricultural applications and scientific understanding.  Soil moisture, temperature and matric potential were monitored at the Living Filter Waste Treatment facility near the campus of Penn State University in State College, Pennsylvania.  At the Living Filter, treated waste water is applied as irrigation to both forested and cropped sites, in regular, 12 hour irrigation events, weekly to monthly, depending on water supply and the irrigation needs of the cropped sites.  These irrigation events served as controlled experiments, which we analyzed to determine the seasonal controls on preferential flow initiation, vertical water and pressure velocities, and patterns of drainage and ET water removal from the soil profile.  These analyses serve to develop a synthesized understanding of water fluxes and stores at the site.