HR: 0800h
AN: H31D-0415    [Abstracts]
TI: Are Advecting Processes in the Vadose Zone of the Albuquerque Basin Altering the Conductive Heat Transfer Signal From Surface Temperature Change ?
AU: * Reiter, M A
EM: mreiter@nmt.edu
AF: New Mexico Bureau of Geology and Mineral Resources, New Mexico Institute of Mining and Technology, 801 LeRoy Place, Socorro, NM 87801 United States
AB: Temperature measurements ( T logs ) in the deep vadose zone ( about 60m to 120m depth ) of the Albuquerque Basin have been repeated over the past year at four piezometer nests. The measurements were made with a very fast time response thermistor, which allowed data to be taken every meter going down hole. This depth resolution of temperature data permits a rather detailed observation of the thermal regime in the vadose zone. At one site ( Lincoln Middle School ) the temperature profile below 20m clearly shows a conductive profile resulting from surface temperature change due to urbanization and nearby ( about 10m ) asphalt pavement. At the other three sites the cause of non-linearity in the T log is less certain. Temperature records suggest about 1 deg C increase in near surface air temperature over the past thirty years at the Albuquerque airport; although this data may also be affected by urbanization. The Tome and 98th Street sites are being approached by paved roads and urbanization. At the Tome site expressions representing horizontal advection are the statistically preferred fit to the T log from about 25m to 58m ( F statistic ). At the 98th Street site an expression representing a surface temperature step best fits the T log from 20m to about 75m; however, the temperature step (about 1 deg C to 2 deg C, 3 to 15 yr ago ) is variable between logs, and the profile of the T log with abrupt discontinuities may suggest other than just conductive heat transfer. The fourth piezometer nest at the Mesa del Sol site is the most remote of the sites considered, with as little nearby surface disturbance as might be expected for a drilling location. At depths between 30m and 70m the expressions representing surface temperature change, horizontal advection, and vertical advection, all fit the T log reasonably well. The temperature step expression suggests about 1 deg C to 1.8 deg C surface temperature increase about 13 yr to 28 yr ago. Deeper in the vadose zone, from about 60m to 120m, the expression representing horizontal advection is a generally preferred fit to the T log. Perhaps horizontal liquid flow through perched water zones, steps in the ground water table elevation caused by normal faulting, horizontal variations in barometric pressure effects at depth, and sub horizontal vapor flow moving around permeability barriers on its way to the surface, promote horizontal advection at the Tome and Mesa del Sol sites.
DE: 1832 Groundwater transport
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting