Assessing spatial and temporal variations in an aquifer system using repeat temperature-depth measurements: an example from the Española Basin, New Mexico
Abstract
Over the last six years, students attending the Summer of Applied Geophysical Experience (SAGE) field program have had the opportunity to collect thermal profile data from eighteen monitoring wells in the southern Española basin near Santa Fe, NM. The monitoring wells penetrate a semi-confined aquifer system within the Miocene Santa Fe Group, which consists of Rio-Grande-rift-fill sands, gravels, silts, and clays. Eight of the wells have been measured 2-5 times between 2013 and 2018. Three wells show little change in temperature over this time interval, while temperatures in five wells have changed significantly. For example, two monitoring wells in the La Tierra subdivision north of Santa Fe have changed an average of only 0.02 °C over this timeframe. In contrast, the distribution of temperature in the Skillet well located to the east of the Buckman municipal well field has shifted, with the lower portion of the well cooling and the upper portion of the well warming. The shape of the thermal profile of this well indicates pronounced upflow. Peclet analysis of the curve indicates that the vertical velocity of water flow in the wellbore is decreasing through time, from -0.082 meters per year in 2013 to -0.068 meters per year in 2016. Temperatures in three monitoring wells in the Buckman well field also changed, with an increase of 0.3-0.4 °C between 2014 and 2016. Temperatures in the upper part of the 762-m-deep Cañada well in the center of Santa Fe increased 0.2 °C between 2017 and 2018. The well is returning to thermal equilibrium after drilling disturbances in 2016. Additionally, two permeable aquifers penetrated by the Cañada well induce strong intra-borehole upflow of groundwater within the well. The changes in temperature near the Buckman well field appear to be related to changes in water management practices by the City of Santa Fe. Increased use of water from the Rio Grande and reduced pumping in the well field have allowed water levels to recover. Rising water levels and complex groundwater flow in the discontinuous aquifers in the Santa Fe Group have caused variations in temperature patterns near the recovering well field. This long-term experiment demonstrates the usefulness of repeat thermal-profile measurements in assessing dynamic groundwater flow in recovering aquifer systems.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMNS31C0769K
- Keywords:
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- 0933 Remote sensing;
- EXPLORATION GEOPHYSICSDE: 1829 Groundwater hydrology;
- HYDROLOGYDE: 1835 Hydrogeophysics;
- HYDROLOGYDE: 1880 Water management;
- HYDROLOGY