Estimating flow and transport parameters of unsaturated porous media

Scope and method of study. Three objectives were undertaken related to the description of unsaturated flow and transport. First was the development of an improved method to measure unsaturated hydraulic parameters. This was completed using a Bruce/Klute test in conjunction with a quasi-analytic solution to optimize hydraulic parameters. Second was the extension of the Chloride Mass Balance Method to KCl fertilized, non-arid agricultural areas. Third was to provide a historical interpretation of recharge, evapotranspiration, and runoff at a KCl fertilized field using deep continuous soil chloride profiles in conjunction with long-term meteorological data.; Findings and conclusions. Hydraulic parameters were defined using a testing procedure that can be conducted in approximately one hour or less. The sensitivity of van Genuchten hydraulic parameters was adequate for the sandy loam soil tested. The Chloride Mass Balance Method was applied on a dryland winter wheat plot at the Stillwater Agricultural Research Center. The method was successful and recharge rates were found to be within a range of 12 to 39 mm-yr−1. Modeling of the plots describes the relative magnitude of the different sources and sinks of water for dryland winter wheat production near Stillwater, Oklahoma and such a model has potential to describe the impact that long-term changes of climate might have on regional grain production.