RESEARCH INTERESTS

Water Content Determination in Soils

I have a broad interest in determining the water content in soils using a variety of methods. Most recently work has focused on the use of electromagnetic methods including time domain reflectometry (TDR), time domain transmission (TDT), impedance probes and capacitance probes such as the Enviroscan. All of these methods determine water content indirectly; for example TDR measures signal travel time, which is related to the dielectric properties of the soil from which water content is determined. Our interest is to improve both steps of instrument calibration, from instrument measurement to dielectric and from dielectric to water content.

Water Content Determination in porous media

EM methods of water content determination

Field Hydrology and Mapping Soils Using EM Methods

The development of electrical sensors for determining water content has revolutionized our ability to measure rapid below ground hydrological events. This has been applied to the study of irrigation of potato crops in work in the S.E. of England. Sensor measurements indicated that water applied to a traditional ridge furrow system wasn’t wetting the area around the growing tubers. The research indicated that this was caused by soil water repellency and could be over come by using beds instead of ridges.

Enhancing spatial mapping of soil properties is a key aim within our group. We are interests in mapping salinity using non-invasive electromagnetic survey and other soil properties such as texture. We are also interested in developing sensor platforms to map water content for both commercial and environmental applications. Preliminary work has focused on the development of mobile sensor platforms for determining water content. Work conducted at the Salinity Lab (USDA-ARS) in California led to the development of a platform that could determine water content, bulk soil EC and soil temperature.

Avalanching of Granular Materials

Granular materials behave in some unusual ways. Granular materials have properties intermediate to a fluid and solid. They can flow or adopt ridged behavior when confined. Avalanching can cause segregation of particle sizes creating the appearance of banding.

Structural and electrical properties

Structure at the grain scale influences transport properties from water flow to gas flow. Structure is difficult to quantify and we are constantly seeking new ways to quantify and define structural arrangement in porous media.