Revealing Soil Hydraulic Properties

North Carolina State University, Raleigh NC

Investigators

Abstract

Understanding of water storage and movement in soil is critically important to solve a wide range of agricultural, engineering, and environmental problems. The soil hydraulic properties that control water storage and movement are highly variable in time and space, and difficult to measure with existing technologies. This research seeks to develop models that use more easily-measured soil thermal and electrical property values to estimate soil hydraulic property values. These models can be used with existing measurement technologies by scientists and engineers working to address a wide range of national and global challenges related to food, energy, and environmental security. The project will also provide training opportunities for a post-doctoral scholar, and both graduate and undergraduate student researchers. Soil hydraulic properties control transitions in soil water content, thereby driving myriad processes in the terrestrial hydrologic cycle. Capability to measure and predict soil hydraulic properties is thus critically important, yet remains a major limitation for the hydrologic sciences. Owing to relatable influences of soil structure on hydraulic, electrical, and thermal properties, it is hypothesized that more-easily measured soil electrical and thermal properties can be used together as surrogates to determine hydraulic properties. The proposed investigation seeks both to better understand fundamental relationships among soil hydraulic, electrical, and thermal properties for intact soils, and to develop approaches for in situ estimation of soil hydraulic properties from surrogate electrical and thermal property data. Thermo-time domain reflectometer sensors will be used to measure soil electrical, thermal, and hydraulic properties of intact and repacked samples from field sites in North Carolina and Iowa, as well as for in situ measurements in the field. The collected dataset will support modeling efforts for the research team as well as the broader research community. If successful, the proposed work will immediately enable in situ hydraulic property determinations that are not currently possible with any existing approaches. And because the fundamental measurements are thermal and electrical properties, the basic approach can also potentially be extended to a range of sensing platforms. The project will include both graduate and undergraduate research experience (REU) training opportunities, and a short-course for non-affiliated researchers on the measurement of soil thermal and electrical properties. The proposed effort aims to advance discovery and understanding for fundamental hydrological processes while promoting teaching, training, and learning for diverse students and other researchers. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.