[Enviro-lunch] Reminder of the lunch and talk today

[Toshiyuki Bandai]

Hello all,



Today, Dr. John Nimmo from USGS will present about unsaturated zone preferential flow. We have a light lunch with him from 11 am at open space next to SE2 building and talk from 12 pm in SE2 224.  Zoom link is also available from 12 pm.


Zoom link: https://ucmerced.zoom.us/j/175736103



Title: Unsaturated zone preferential flow-Unexpected effects for ecosystems and hazardous-waste containment

Abstract: Preferential flow along common subsurface paths such as wormholes and fractures moves water through the unsaturated zone faster and more directly than diffuse or capillary flow through the bulk of soil matrix material. In ecosystems preferential flow is vital for the efficient distribution of water through the root zone for the optimal use of plants. Field experiments in a restored tropical dryland forest in Hawaii demonstrate that the plants themselves, through their ordinary growth and decay processes, can modify the soil over several years to enhance the preferential flow that is beneficial to them. At near-surface hazardous waste sites, minimization of preferential flow is important for contaminant containment. Field experiments at a simulated waste trench in Idaho show that common landfill construction practices can effectively destroy macropore preferential flowpaths, though additional effects such as destruction of flow-inhibiting natural layer boundaries may offset the beneficial effects of macropore destruction. Ongoing research on the processes of preferential flow has produced significant insights in recent decades. A major current need is for predictive methods to incorporate the improved understanding that has been achieved.

[John Nimmo.png]


Bio: John Nimmo is active in Unsaturated Flow Research in Menlo Park, California, USA. He also is Research Physicist Emeritus with the U.S. Geological Survey, having been actively employed at the USGS from 1981 to 2020. During most of his USGS career, he was Chief of the Unsaturated Flow Processes Project. His research primarily pursues process understanding and estimation methods for fundamental unsaturated-zone flow processes, with particular emphasis on preferential flow. This work is directed toward applications in water-resource assessment, subsurface contaminant fluxes and vulnerabilities, and soil-water dynamics of natural and altered ecosystems. He pursues these largely through mathematical modeling and development of theory, and additionally in collaborations involving field and lab experiments. He writes review articles and basic reference materials that draw on his knowledge and experience gained during more than four decades of research on unsaturated flow (jrnimmo at usgs.gov<mailto:jrnimmo at usgs.gov>)



Sincerely,

co-host: KJ Min, Manisha Dolui, Toshiyuki Bandai, Jennifer Alvarez

faculty coordinator: Asmeret Asefaw Berhe
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