Description, analysis, and interpretation of an infiltration experiment in a semiarid deep vadose zone

Over the past 15 years, the University of Arizona has carried out four controlled infiltration experiments in a 3, 600 m², 15 m deep vadose zone during which the evolution of moisture content and matric potential was monitored and the subsurface stratigraphy, texture, and bulk density were characterized. This chapter will first provide a brief overview of the site characteristics and the available data. Subsequently a geospatial analysis using old and recently acquired data will be carried out to demonstrate that a vertical domain trend due to alluvial layering must be accounted for. The resulting model for subsurface texture is used to reanalyze a neutron probe calibration set, such that unbiased texture-dependent estimates of soil moisture become possible. The resulting models are applied to the third infiltration experiment conducted at the site (January 2001 to February 2002) and interpreted with moment analysis based on depth-mean moisture contents. The work presented here is a first step towards a full reanalysis of the site's data, which in future publications will also include flow and transport modeling and an assessment how much data and of what kind are needed to build an acceptable vadose zone model.