Controlled Source Audio-Magnetotellurics (CSAMT) surveys were conducted in 2012 in the Tucson Mountains as a continuation of the 2010 and 2011 Laboratory for Advanced Subsurface Imaging (LASI) field studies in this area. This geologic setting was chosen for its high-resistivity impermeable volcanic layer overlaying porous sedimentary layers. This type of structure has potential for water resources and as a reservoir for compressed air energy storage (CAES). The data from 2,500 meters of CSAMT survey lines generated 900 meter-deep resistivity versus elevation cross-sections and six plan maps of the depth and elevation to the buried conductive layer. Our results are generally in agreement with the geologic cross sections developed by Lipman (1993) and previous TEM data that confirmed the presence of a deep conductive layer beneath a resistive volcanic sequence.

To assist the United States Geological Survey with an on-going groundwater study around Old Yuma Mine in Tucson, Arizona, the University of Arizona GEN/GEOS 416/516 Field Studies in Geophysics class conducted geophysical surveys along two transects near the mine. Transect 1 was situated across the mine site; Transect 2 was located to the northeast in a nearby residential area. The methods used were gravity, magnetics, transient electromagnetics (TEM) and inductive electromagnetics (Geonics EM-31, and Geonics EM-34). The goal was to use these data to investigate the subsurface density, magnetic susceptibility, and electrical conductivity contrasts. A large gravity anomaly was observed on Transect 1 where it crosses both a mapped fault and the Old Yuma Mine; the anomaly is thought to represent a density contrast related to the Mine and fault. A smaller gravity anomaly was observed on Transect 2, corresponding in location along the profile to a large anomaly in the Transect 2 magnetics data. These anomalies are possibly related to the local lithology. A second magnetics anomaly was observed on Transect 1; this anomaly was also visible in the EM-31 and EM-34 data and could be due to the presence of a nearby wash. Other variations in the magnetics and EM-31/34 data consisted of narrow peaks associated with cultural interference, and the EM-31/34 data showed no large conductivity change in the shallow sediments. Interpretation of TEM data for Transect 1 was limited by the wide station spacing; much of the cross-section’s resistivity contrasts were interpolated over a large distance. The TEM cross-section for Transect 2 displayed higher resistivity on the northwest side and lower resistivity on the southeast side of the transect. Since the mapped fault, if projected northwards, would pass through the middle of Transect 2, it is thought that this resistivity contrast represents the location of the fault. It is hoped that the results of these surveys will be beneficial to the USGS in further work at Old Yuma Mine.

The Tucson International Airport Area (TIAA) Superfund site is an approximately ten square mile area in southeast Tucson, Pima County, Arizona in which several known contaminated water plumes have been identified, which are the result of improper disposal of industrial waste from multiple sources during the past sixty years. The most prominent of these contaminants are 1, 4-dioxane, hexavalent Chromium, and trichloroethylene (TCE), which exist in varying concentrations throughout the site. Groundwater contamination in Tucson was first identified in the 1950’s; however TIAA was not recognized as a Federal Superfund site until 1982. Since then, much work has been carried out in an attempt to fully understand and remediate the contamination in the area. This study focusses on four areas within the TIAA: Samsonite North, Aero Park Blvd South (EW line), Aero Park Blvd South (NS line), and EPA-03. Several geophysical techniques have been used to understand the subsurface structure in the area and to better understand the contamination plume and its movement. Using the Transient Electromagnetic (TEM) technique at three sites: Samsonite North, Aero Park Blvd South (NS line and EW line), and EPA-03, it was found that there was a low-resistivity region going through the EPA-03 site, two low-resistivity regions through Aero Park Blvd South (NS line), and three low-resistivity zones through Aero Park Blvd South (EW line). These channels were consistent with the overall orientation of water flow in the region which is toward the Northwest. These zones may indicate higher moisture content, and this may be caused by porous, water-filled channels passing through the sites. These zones could also indicate non-porous clay-rich regions, which would also be low resistivity. The effect of a pipeline on the measurements in the Samsonite North area made it difficult to reach any useful conclusions at this site.

A study was made of the response of six kinds of melons to different nitrogen fertilizer rates when grown with drip irrigation. Results indicated a general response of petiole nitrate and yields to increasing N rates, depending on the kind of melon. The study will be continued in 1990 and include water and N rates with three kinds of melons.

Studies were carried out at the Safford Agricultural Center using some soil amendments as anti-crusting agents. The results are promising in terms of improved stands on soils subject to crusting. Additional research is needed in order to determine proper rates which will reduce crusting without being toxic to the emerging seedlings.

An understanding of the expected variability in irrigated crops under field size, surface irrigation conditions is needed to improve irrigation designs and water management scheduling procedures. The objective of this work is to describe water application uniformity under an efficient level -basin irrigation system and the variability of water use (soil water depletion) for three levels of irrigation and two basin lengths for a wheat crop. High water distribution uniformities with a level -basin irrigation system did not necessarily result in maximum irrigation application efficiencies where variations in soil -water factors were greater on a drier irrigation treatment than medium or wet treatment. Variations in soil water depletion were found for all irrigation treatments with the largest variation (13 %) occurring for the drier treatment. Spatial dependence was exhibited for soil water depletion but not necessarily for seasonal irrigation water applications.

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.