CAREER: A Mechanism for Rapid Soil-water Transport

University Of South Carolina At Columbia, Columbia SC

Investigators

Abstract

9985345 Torres Soil with highly non-linear water retention or conductivity functions may exhibit both rapid and slow soil-water advection processes. I hypothesize that a near-zero threshold pressure head separates a non-linear unsaturated hydraulic conductivity function into regions where constant and where hydraulic conductivity and soil-water content pressure head). I propose that high intensity bursts of rainfall upon a soil at or near the threshold pressure head will produce a subtle but rapidly advancing pressure wave through the soil profile. The pressure wave will cause a large increase in K, the release of stored soil-water, and the rapid development of high pore pressures. Such a "pressure wave-release mechanism" may lead to water potential conditions favoring flow into non-capillary sized pores (macropores). Hence, the "pressure wave-release hypothesis" may describe conditions that dictate when soil macropores "switch on". The combined effects of water transported by pressure wave-release and the initiation of macropore flow may lead to the rapid development of high pore pressures and slope instability. I will conduct theoretical, laboratory and field experiments to investigate the pressure wave-release hypothesis and its effect on rates of water advection and pore pressure development. The educational initiatives herein directly link experimentation with observation, and they create a unique opportunity for students to acquire "hand on" hydrology experience in a field laboratory. Easy to use instrumentation and analyses will facilitate undergraduate research on 1) rainfall-runoff processes and 2) subsurface path length effects on buffering capacity of an urbanized riparian corridor. Approximately 20 faculty expressed their support for the proposed research-education facility; consequently, the field hydrology laboratory can become an integral part of thousands of students' education each year.