Moira Poje voted one of the “Best of SAGEEP” for her presentation:
ELECTROFACIES MAPPING OF THE SANTA CRUZ AND SAN PEDRO ALLUVIAL FLOODPLAINS WITH MULTIPLE GEOELECTRICAL METHODS
At this year’s Symposium on the Application of Geophysics to Engineering and Environmental Problems (SAGEEP), HGI’s Moira Poje was voted one of the “Best of SAGEEP” for her presentation on Electrofacies Mapping Of The Santa Cruz And San Pedro Alluvial Floodplains With Multiple Geoelectrical Methods.
Moira’s presentation examines two sites in southeastern Arizona to understand the soil environment better and add context for hydrogeological investigations. It shows how spatially continuous geophysical information paired with well sampling and geomorphological site characterization provides insight into water flow interactions with sediment deposits in the area. Moira and her team collected nearly 7 miles of data for the Santa Cruz River study in hot Arizona weather and were chased constantly by tumbleweeds.
Moira’s accomplishment earned her the honor of delivering the presentation again at the 2021 International Near Surface Geoscience (NSG) conference in Bordeaux, France. Unfortunately, Moira does not get to go to France as the meeting is online due to the covid pandemic. Nonetheless, she will have the opportunity to present at the prestigious event with all the others voted “Best of SAGEEP.”
Or see it at the NSG conference August 30th 2021
Moira’s Abstract –
Electrical resistivity can be used as a proxy for soil specific parameters and structure that is important for irrigation optimization, contaminate mapping, groundwater withdrawal, and mineral resource exploration. Often, electrofacies can be directly tied to hydrofacies or soil horizons and allow researchers to have a broader means of subsurface investigation relative to the limitations of borehole data. In this work, we examine two sites in southeastern Arizona to better understand the soil environment in order to add context for hydrogeological investigations. At the first site, south of Tucson along the Santa Cruz River, farmland is comprised of valley fill and undifferentiated alluvial sediments that are littered with over 1700 sinkholes. The Upper Santa Cruz River is an ephemeral flow which passes pecan orchards and mining operations before reaching the Tohono O’odam Nation and the City of Tucson. There has been interest in characterizing the hydrogeology to access the water resources in the area and further define the channelization mechanisms along the upper Santa Cruz River. At the second site, we conducted an electrical resistivity and induced polarization study across the San Pedro River near St. David to define the near surface electrofacies. The electrically conductive, buried clay unit of the St. David Formation, which controls much of the shallow hydrogeological regime, has a variable topography depending on proximity to the river. At both sites we have sufficient borehole data to provide broad correlations to the important formations that act as aquifers and aquitards. Consequently, we show how the use of the high-resolution, spatially continuous geophysical information, paired with well sampling and prior geomorphological characterization of the site, can provide insight into how water flow interacts with sediment deposits in the area.