Increased land use change near fragile ecosystems can affect the ecosystem energy
balance leading to increased global warming. One component of surface energy balance
is soil storage heat flux. In past work, a complex thermal behavior was noticed in the
shrink-swell sediment of the upper Nueces Delta (upper Rincon) during summer months
as it dried. Soil storage heat flux was found to first increase, then decrease, as the soil
dried. It was suggested that the complex behavior was due to the relationship between
thermal diffusivity and soil moisture, where thermal diffusivity increases to a local
maximum before decreasing with respect to decreasing soil moisture. This study
explores the observed phenomenon in a controlled laboratory environment by relating
the sediment shrinkage curve to changing heat transfer properties.
Due to the complicated nature of the drying-shrinking sediment, it was necessary to
measure the sediment shrinkage curve and heat transfer properties in separate
experiments. The shrinkage curve was found by correlating measured sample volume
with gravimetric moisture content. Heat transfer properties were found using a single
needle heat pulse probe. A normalized gravimetric moisture content was used as a
common variable to relate the shrinkage curve and heat transfer data. Data suggests that the shrink-swell Rincon sediment portrays different behavior in
drying than that which occurs for a non-shrink-swell soil. For the shrink-swell Rincon
sediment, thermal conductivity is seen to increase with decreasing moisture, the
suggested mechanism being increased surface area contact between particles as the
shrinking sediment dries.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/4830 |
| Date | 25 April 2007 |
| Creators | Cramer, Nicholas C. |
| Contributors | Heilman, Jim L. |
| Publisher | Texas A&M University |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Thesis, text |
| Format | 897049 bytes, electronic, application/pdf, born digital |
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