CAREER: A Mechanism for Rapid Soil-water Transport

9985345土壤具有高度非线性的保水或导水功能，可表现出快速和缓慢的土壤-水平流过程。我假设，一个接近于零的门槛压力水头将一个非线性的非饱和渗透系数函数分成恒定和恒定的区域(渗透系数和土壤水分压力水头)。我认为，当降雨强度达到或接近临界压力水头时，土壤上会产生一种细微但快速推进的压力波，穿过土壤剖面。压力波会导致K的大量增加，储存的土壤水的释放，以及高孔压的迅速发展。这种“压力波释放机制”可能导致水势条件有利于流入非毛管大小的孔隙(大孔隙)。因此，“压力波释放假说”可以描述决定土壤大孔隙何时“开启”的条件。压力波释放输水和大孔隙流的共同作用可能导致高孔压的快速发展和边坡的失稳。我将进行理论、实验室和野外实验，研究压力波释放假说及其对水平流率和孔隙压力发展的影响。这里的教育举措直接将实验与观测联系起来，为学生创造了在野外实验室获得“亲身”水文学经验的独特机会。易于使用的仪器和分析将有助于本科生研究1)降雨径流过程和2)地下路径长度对城市化河岸走廊缓冲能力的影响。大约20名教职员工表示支持拟议的研究-教育设施；因此，野外水文学实验室可以成为每年数千名学生教育的一个组成部分。

9985345TorresSoil 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.