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USGS2024

Identifying transportation data and system needs for a Federal lands transportation data platform

Executive Summary Modern transportation and land-use planning efforts include information from many sources to address topics such as safety, efficiency, commercial, and social needs. This wide breadth of topics provides opportunities for collaboration and development of common tools for diverse users. In many cases, different information systems provide the spatial data and geographic content necessary for transportation and land-use planners to consider multiple lines of evidence. The Federal Highway Administration Office of Federal Lands Highway (FLH) and Federal Land Management Agency partners use detailed spatial and quantitative data to inform transportation decisions. However, logistic challenges to data sharing exist because data are often managed by separate agencies; data-exchange frameworks and interagency data agreements are insufficient; and consistency from aggregated data requires maintenance, coordination, and supporting infrastructure. The FLH and U.S. Geological Survey collaboratively examined (1) use and availability of spatial data for transportation planning and (2) a possible mechanism to use more shared and consistent data in a common planning environment. The goals of this collaborative effort were to describe data needs from the perspective of planners and to identify opportunities for shared data resources. Results presented here focus on two workshops and a subsequent investigation of data and tools available from partner agencies. The objectives of this report are to (1) describe information used in transportation planning with geographic data; (2) identify spatially explicit data that inform transportation plans and could be shared among all partners; and (3) describe current platforms, planning and administrative opportunities, and potential barriers to developing an integrated planning tool. Key information and data needs were identified in three major classes: system, user, and influential factors. System data are parts of the transportation network and information about the condition of individual segments and the network. User data provide details about the function of the system and insights into potential needs; for example, user trips between source and destinations inform road and network demands that can lead to congestion and safety issues (in the future, user data might also include scenarios and projections based on land-use plans). Influential data represent social and environmental factors that influence transit demands and network conditions. These factors could be popular locations or seasonal events that influence demand and congestion; wildlife habitat or migration intersections that affect safety and management priorities; or geologic features that influence hazards, maintenance, and safety. Responses described here provide specific information for web-tool design and give a framework for interagency communication and cooperation to address specific information needs for integrated planning. Existing web-mapping and web-services, and the data that inform them, are also described. Commonly, these data are created and published by one agency, and the core users are outside of that agency; for example, threatened species distributions are published by the U.S. Fish and Wildlife Service for consideration by planners in advance of National Environmental Policy Act (42 U.S.C. 4321 et seq.) evaluation. This report is provided to inform FLH leaders and Federal Land Management Agency partners by articulating user needs and requirements for integrated planning tool(s). Programmers creating a secure web-based data-sharing platform (with data-viewing, -analysis and -download functions) can use the information presented here to organize data and user interfaces. This integrated perspective can help FLH and Federal Land Management Agency partners develop transportation networks that better serve the needs of people in local communities and across States and the Nation.

Open-File Report↗
USGS2025

Python Hyperspectral Analysis Tool (PyHAT) user guide

This report is a user guide for the 0.1.2 release of the Python Hyperspectral Analysis Tool (PyHAT) and its graphical user interface (GUI). The GUI is intended to provide an intuitive front end to allow users to apply sophisticated preprocessing and analysis methods to spectroscopic data. Though the PyHAT package has been developed with a particular focus on laser-induced breakdown spectroscopy (LIBS), the package uses a simple comma separated values (CSV)-based data format and is readily applicable in other spectroscopy applications. This guide provides background information about the package and its capabilities. It also provides practical guidance on usage and example workflows for a wide variety of datasets.

Open-File Report↗
USGS1961

Geology of uranium in the Chadron area, Nebraska and South Dakota

The Chadron area covers 375 square miles about 25 miles southeast of the Black Hills. Recurrent mild tectonic activity and erosion on the Chadron arch, a compound anticlinal uplift of regional extent, exposed 1900 feet of Upper Cretaceous rocks, mostly marine shale containing pyrite and organic matter, and 600 feet of Oligocene and Miocene rocks, mostly terrestrial fine-grained sediment containing volcanic ash. Each Cretaceous formation truncated by the sub-Oligocene unconformity is stained yellow and red, leached, kaolinized, and otherwise altered to depths as great as 55 feet. The composition and profile of the altered material indicate lateritic soil; indirect evidence indicates Eocene(?) age. In a belt through the central part of the area, the Brule formation of Oligocene age is a sequence of bedded gypsum, clay, dolomite, and limestone more than 300 feet thick. Uranium in Cretaceous shale in 58 samples averages 0.002 percent, ten times the average for the earths crust. Association with pyrite and organic matter indicates low valency. The uranium probably is syngenetic or nearly so. Uranium in Eocene(?) soil in 43 samples averages 0.054 percent, ranging up to 1.12 percent. The upper part of the soil is depleted in uranium; enriched masses in the basal part of the soil consist of remnants of bedrock shale and are restricted to the highest reaches of the ancient oxidation-reduction interface. The uranium is probably in the from of a low-valent mineral, perhaps uraninite. Modern weathering of Cretaceous shale is capable of releasing as much as 0.780 ppm uranium to water. Eocene(?) weathering probably caused enrichment of the ancient soil through 1) leaching of Cretaceous shale, 2) downward migration of uranyl complex ions, and 3) reduction of hydrogen sulfide at the water table. Uranium minerals occur in the basal 25 feet of the gypsum facies of the Brule formation at the two localities where the gypsum is carbonaceous; 16 samples average 0.066 percent uranium and range up to 0.43 percent. Elsewhere uranium in dolomite and limestone in the basal 25 feet of the gypsum facies in 10 samples averages 0.007 percent, ranging up to 0.12 percent. Localization of the uranium at the base of the gypsum facies suggests downward moving waters; indirect evidence that the water from which the gypsum was deposited was highly alkaline suggests that the uranium was leached from volcanic ash in Oligocene time.

Open-File Report↗
USGS1968

Ground-water exploration using the resistivity method on the Hawaiian Islands of Oahu and Hawaii

Thirty-six resistivity soundings were made on the islands of Oahu and Hawaii to determine the applicability of galvanic resistivity methods for locating fresh-water aquifers in the State of Hawaii. Soundings were made on the northwestern part of the island of Oahu near the town of Waialua and on the island of Hawaii on the "saddle" area near Pohekuloa and the Humuula sheep station. On Oahu, the geoelectrical study indicates that correlation among four stratigraphic units underlain by a vesicular basalt basement is possible. The electrical soundings indicate that it is feasible to determine the approximate depth to the fresh-saline water interface within the basalt. Two Schlumberger soundings with electrode spacings, AB/2, reaching 6,000 feel give sounding curves of the maximum and minimum type whose terminal branches indicate that the true resistivity of basalts saturated with sea water, in the survey area on Oahu, is about 30-40 ohm-m. On the island of Hawaii, an exploratory well drilled in basalt to a depth of 1,001 feet proved to be dry. In the area of this well, two deep soundings were made using the Schlumberger and the equatorial arrays. Although additional soundings at various orientations and larger spacings are needed, there appears to be a conductive layer below 1,600 feet which may represent basalt saturated with fresh water.

Hawaii↗
USGS1976

Ground-water hydrology of the Cocoa well-field area, Orange County, Florida

The city of Cocoa, Brevard County, Florida, supplies water for much of central Brevard County including Cape Kennedy and Patrick Air Force Base. The water supply is obtained from a well field in east Orange County. Many of the easternmost wells in that well field yield salty water (chloride concentration greater than 250 milligrams per liter). The interface between the fresh and salty water in the west part of the well field occurs at a depth of about 1,400 feet. An upward hydraulic gradient exists between the the lower (salty) zones and the upper, or pumped zones of the Floridan aquifer in the west part of the well field. Secondary artesian aquifers in the well-field area are relatively high-yielding but are of limited areal extent. However, they are suitable as a source of water for supplemental supply or for artificially recharging the Floridan aquifer. Fresh water was transferred by siphon from a secondary artesian aquifer to the Floridan aquifer at 90 gallons per minute. Artificial recharge and recovery experiments show that it is feasible to retrieve fresh water stored in salty zones of the Floridan aquifer. (Woodard-USGS)

Open-File Report↗
USGS1975

Techniques for water demand analysis and forecasting: Puerto Rico, a case study

The rapid economic growth of the Commonwealth-of Puerto Rico since 1947 has brought public pressure on Government agencies for rapid development of public water supply and waste treatment facilities. Since 1945 the Puerto Rico Aqueduct and Sewer Authority has had the responsibility for planning, developing and operating water supply and waste treatment facilities on a municipal basis. The purpose of this study was to develop operational techniques whereby a planning agency, such as the Puerto Rico Aqueduct and Sewer Authority, could project the temporal and spatial distribution of .future water demands. This report is part of a 2-year cooperative study between the U.S. Geological Survey and the Environmental Quality Board of the Commonwealth of Puerto Rico, for the development of systems analysis techniques for use in water resources planning. While the Commonwealth was assisted in the development of techniques to facilitate ongoing planning, the U.S. Geological Survey attempted to gain insights in order to better interface its data collection efforts with the planning process. The report reviews the institutional structure associated with water resources planning for the Commonwealth. A brief description of alternative water demand forecasting procedures is presented and specific techniques and analyses of Puerto Rico demand data are discussed. Water demand models for a specific area of Puerto Rico are then developed. These models provide a framework for making several sets of water demand forecasts based on alternative economic and demographic assumptions. In the second part of this report, the historical impact of water resources investment on regional economic development is analyzed and related to water demand .forecasting. Conclusions and future data needs are in the last section.

Open-File Report↗
USGS1976

Potential for development of ground water at a test site near Truro, Massachusetts

An aquifer test was carried out at a possible ground-water development site in Truro, Massachusetts. Average lateral hydraulic conductivity for material in the screened interval of the test well is 216 feet per day. Specific yield of the material at water-table depth is about 0.10. Anisotropy, or ratio of lateral hydraulic conductivity to vertical hydraulic conductivity, is between 1 and 5 for the uppermost 60 feet of saturated material, but is probably much higher at greater depths. Calculation of drawdown after pumping 200 days at 1 million gallons per day indicates lateral intrusion of saline water from the sea would not reach the well and that the area of ground-water contribution would be sufficient to intercept an amount of average annual recharge equal to pumpage. Using the previously determined aquifer constants and the maximum drawdown after 200 days of pumping at 1 million gallons per day, it was determined that a stable upconing adjustment of the fresh water/saline-water interface would occur below the pumping well, and saline water would not reach the well through vertical intrusion. (Woodard-USGS)

Open-File Report↗
USGS1977

Reconnaissance geologic study of the Vazante zinc district, Minas Gerais, Brazil

The Vazante district, Minas Gerais, 130 km south of Paracatu, produces nearly all of Brazil's zinc metal. The district is situated on the western side of the Late Precambrian Bambul basin and along the eastern and leading edge of the north-trending Brazilian orogenic belt (ca. 600-500 m.y. old) that borders the western margin of the basin. Reconnaissance study indicates that bedding and low-angle thrust faulting, folding, and low-grade metamorphism dominated the structural development of the district. The structural trend within the district is northeasterly, and dips 20?-45 ? NW. Three sets of folds developed during the main period of eastward thrusting of older Precambrian rocks over the western margin of the Bambui basin. A fourth fold set is transverse to the regional trend. The rocks in the district are tentatively assigned to the Paraopeba Formation of the Bambui Group and are designated A through C in ascending order. Unit A is phyllite to phyllitic siltstone. Unit B consists of interbedded dolomitic limestone and marl-limestone. Irregularly distributed limestone ledges 20 to 100 m thick have the appearance of boudins. Their origin is attributed to a combination of rapid lateral facies changes and differential movement at different structural levels along bedding and low-angle thrust faults, with the formation of tear faults vertically limited by the thrust faults. Unit C consists of interbedded siltstone, dolomitic limestone, and sandstone. Phyllitic rocks along member interfaces in units B and C and at the base of unit C indicate differential penetrative deformation and bedding faulting. The contacts between units A, B, and C are interpreted to be low-angle or bedding faults, and their original stratigraphic positions with respect to each other is unknown. Zinc silicate minerals (hemimorphite and willemite) occur in a folded breccia zone in the lower part of unit B. The breccia zone is interpreted to be tectonic in origin, having formed along the step of a step-bedding-plane fault during the Brazilian orogeny. The zinc is probably syngenetic, and ore deposition in the breccia may have occurred during Brazilian time. Broad uplift and deep weathering of the region took place during late Mesozoic and Cenozoic time. Reserves may be as high as 3 million tons of zinc metal.

Open-File Report↗
USGS1977

Atlantic Margin Coring Project 1976: Preliminary Report on Shipboard and Some Laboratory Geotechnical data

This report presents reduced shipboard geotechnical data collected during the 1976 Atlantic Margin Coring Project; results of laboratory tests of specific gravity, water content, bulk density, and Atterberg limits; and sedimentation-compression e log p curves showing consolidation. A description of the procedures used at sea and in the laboratory and a short preliminary summary of the shipboard results also is included. The involvement of Marine Geotechnical Laboratory (MGL), Lehigh University, personnel in the 1976 Atlantic Margin Coring Project can be divided into two phases. In Phase One, the Lehigh nuclear-transmission densitometer was rebuilt to process cores at sea more rapidly than previously had been done in the laboratory, the equipment was assembled and tested aboard the Glomar Conception, and at-sea geotechnical measurements were made during the duration of the cruise. Data sheets were prepared for both unopened core sections (Appendix III) and split-core samples (Appendix IV). Completed data forms are on file at the MGL and at the Geological Survey in Woods Hole. Phase Two included reduction of the shipboard data, testing of all geotechnical samples taken from cores split aboard the ship, and certain other analytical work ashore utilizing the geotechnical measurements. Water content and weight/volume bulk density tests were performed at the MGL. Specific gravity and Atterberg limit tests and certain calculations were performed by Geological Survey personnel at the Corpus Christi, Texas, laboratory. During Phase One, 37 unopened, 1.5-m-long core sections were selected by Lehigh personnel for subsequent static and dynamic triaxial and consol­idation testing ashore. The disposition of these cores is controlled by Geological Survey Project personnel; they are not further discussed in this report. A depth convention has been adopted in this report for the convenience of labeling core sections and analyzing the data. Each 9.2-m-long (30 ft) core liner had a maximum penetration depth referenced to the water-sediment interface; these data are given in Hathaway, et al. (1976). Each 9.2-m-long core liner was cut into six or fewer sections, each 1.5 m (5 ft) in length, aboard the ship. To the maximum penetration depth, 0.2 m was subtracted to obtain the depth at the bottom of the first 1.5 m section above the core catcher. To obtain values at the bottom of the remaining 1.5 m sections, an additional 1.5 m was added for each section. The depth of the bottom of each core section was used for all values obtained using the nuclear densitometer. Tests within core sections and samples collected from core sections were assigned depths based on the location of the test or sample within the core section. It should be clearly recognized that all depths within a 9.2-m-long core are estimates of the true depth, which cannot be uniquely calculated because of the uncertainty of the relationship of sediment contained within the core liner to true in situ depths. This report is considered to be preliminary because the author has not had access to the final lithologic logs or paleontological results, upon which a more accurate description of geotechnical results could be based. It would be inappropriate to comment on geological hazards until this information is made available.

Atlantic Ocean↗
USGS1978

Sonobuoy refraction data near Kodiak, Alaska

A total of 88 unreversed sonobuoy refraction lines were shot over the continental shelf and slope near Kodiak, Alaska, in 1976 and 1977. Useful results were obtained from 59 of these attempts. The field measurements were carried out aboard the USGS research vessel SAMUEL P. LEE. The refraction lines were concentrated in three major areas: (1) the outer continental shelf from Portlock Bank to Chirikof Island; (2) Shelikof Strait; and (3) the continental slope between Kodiak Seamount and Portlock Bank. Sound sources used during the refraction survey included 1326 and 2501 cubic inch air gun arrays, and a 160 kilojoule arcer. Most of the sonobuoys employed were U. S. Navy SSQ-41A and SSQ-41B models; a few commercial buoys (Refraction Technology and Fairfield Industries) were also used. Line lengths ranged from 5 to 30 km, and maximum subbottom penegration was 5.1 km. The field data were recorded on magnetic tape as well as a conventional facsimile recorder. Data reduction was accomplished using the slope-intercept method with the assumption of plane layers. A computer program was used to calculate interval velocities, thicknesses, reflection times, and critical distances for each of the refracting layers; the program also generated a travel time plot showing refracted arrivals as well as wide angle reflections associated with each of the interfaces.

Alaska↗
USGS1978

A computer program for simulating salinity loads in streams

A FORTRAN IV program that simulates salinity loads in streams is described. Daily values of stream-discharge in cubic feet per second, or stream-discharge and specific conductance in micromhos, are used to estimate daily loads in tons by one of five available methods. The loads are then summarized by computing either total and mean monthly loads or various statistics for each calendar day. Results are output in tabular and, if requested, punch card format. Under selection of appropriate methods for estimating and summarizing daily loads is provided through the coding of program control cards. The program is designed to interface directly with data retrieved from the U.S. Geological Survey WATSTORE Daily Values File. (Woodard-USGS)

Open-File Report↗
USGS1979

Summary of hydrologic data for Tampa Bypass Canal System, July 1974 to September 1976

The Tampa Bypass Canal is part of a flood-control project east of the city of Tampa under construction by the U.S. Army Corps of Engineers. It will divert floodwater from the Hillsborough River at points upstream from Tampa through a canal system to McKay Bay. The U.S. Geological Survey began a hydrologic data program in 1974 to provide data needed to identify existing hydrologic conditions and to evaluate the effects of canal construction. A network of surface-water and ground-water sites was designed to monitor changes in nutrients, trace metals, major inorganic constituents, pesticides, and benthic invertebrates along the canal system; to monitor changes in trace elements, common constituents, nitrates, specific conductance, and chlorides in the Floridan aquifer; and to monitor changes in the potentiometric surface of the Floridan aquifer. In 1974-75, the monitoring program consisted of drilling 12 monitor wells and initiation of the surface-water sampling program. In 1976, the program consisted of drilling five additional wells, continuation of the surface-water sampling, initiation of ground-water sampling program, and monitoring of discharge from springs. Water-quality data for nine surface-water sites in the basin were collected at each of the control structure sites, in the tidal portion of the canal, and at each of the major tributaries to the canal system. Fifteen ground-water sites were sampled annually to provide information on ground-water quality. Ten wells were sampled semiannually for dissolved chloride concentrations to provide information on the freshwater-saltwater interface. Ground-water levels were collected at 34 wells in the areas adjacent to the canal to monitor changes in the potentiometric surface in the Floridan aquifer. Discharge measurements from springs along the canal system were made in 1969-73 and 1976 to provide data on the quantity of ground water entering the canal. A daily discharge station was operated at structure S-160 to determine quantity of water flowing from the canal system into the bay.

Florida↗
USGS1979

A study of uranium favorability of Cenozoic sedimentary rocks, Basin and Range Province, Arizona: Part I. General geology and chronology of pre-late Miocene Cenozoic sedimentary rocks

This study focuses attention on Cenozoic sedimentary rocks in the Basin and Range Province of Arizona. The known occurrences of uranium and anomalous radioactivity in these rocks are associated with sediments that accumulated in a low energy environment characterized by fine-grained clastics, including important tuffaceous materials, and carbonate rocks. Most uranium occurrences, in these rocks appear to be stratabound. Emphasis was placed on those sedimentary materials that pre-date the late Cenozoic Basin and Range disturbance. They are deformed and crop out on pedimented range blocks and along the province interface with the Transition Zone. Three tentative age groups are recognized: Group I - Oligocene, pre-22 m.y., Group II - early Miocene - 22 m.y. - 16 m.y., and Group III - middle Miocene - 16 m.y. to 13--10 m.y. Regionally, these three groups contain both coarse to fine-grained red clastics and low energy lighter colored 'lacustrine' phases. Each of the three groups has been the object of uranium exploration. Group II, the early Miocene strata, embraces the Anderson Mine - Artillery region host rocks and also the New River - Cave Creek early Miocene beds-along the boundary with the Transition Zone. These three groups of rocks have been tectonically deformed to the extent that original basins of deposition cannot yet be reconstructed. However, they were considerably more extensive in size than the late Cenozoic basins the origin of which deformed the former. Group II rocks are judged to be of prime interest because of: (1) the development and preservation of organic matter in varying lithologies, (2) apparent contemporaneity with silicic volcanic centers, (3) influence of Precambrian crystalline rocks, and (4) relative outcrop continuity near the stable Transition Zone. The Transition Zone, especially along its boundary with the Basin and Range Province, needs additional geologic investigation, especially as regards the depositional continuity of Group II sediment s.

Arizona↗
USGS1979

Formation and resulfidization of a South Texas roll-type uranium deposit

Core samples from a roll type uranium deposit in Live Oak County, south Texas have been studied and results are reported for Se, Mo, FeS2 and organic-carbon distribution, sulfide mineral petrology, and sulfur isotopic composition of iron-disulfide phases. In addition, sulfur isotopic compositions of dissolved sulfate and sulfide from the modern ground water within the ore bearing sand have been studied. The suite of elements in the ore sand and their geometric relationships throughout the deposit are those expected for typical roll-type deposits with well-developed oxidation-reduction interfaces. However, iron-disulfide minerals are abundant in the altered tongue, demonstrating that this interval has been sulfidized after mineralization (resulfidized or rereduced). Iron disulfide minerals in the rereduced interval differ mineralogically and isotopically from those throughout the remainder of the deposit. The resulfidized sand contains dominantly pyrite that is enriched in 34S, whereas the sand beyond the altered tongue contains abundant marcasite that is enriched in the light isotope, 32S. Textural relationships between pyrite and marcasite help to establish relative timing of iron disulfide formation. In reduced rock outside the altered tongue, three distinct generations of iron disulfide are present. The oldest of these generations consists largely of pyrite with lesser amounts of marcasite. A major episode of marcasite formation contemporaneous with ore genesis postdates the oldest pyrite generation but predates a younger pyrite generation. Resulfidization probably led to the final pyrite stage recognized beyond the altered tongue. Stable isotope data establish that the source of sulfur for the resulfidization was fault-leaked H2S probably derived from the Edwards Limestone of Cretaceous age which underlies the deposit. The deposit formed in at least two stages: (1) a pre-ore process of host rock sulfidization which produced disseminated pyrite as the dominant iron disulfide phase; and (2) an ore-stage process which led to the development of the uranium roll with emplacement of the characteristic suite of minor and accessory elements and which produced abundant isotopically light marcasite. The host rock was modified by a post-ore stage of resulfidization which precipitated isotopically heavy pyrite. Sulfur isotopic compositions of sulfide and sulfate present in modern ground water within the host sand differ greatly from sulfur isotopic composition of iron disulfides formed during the resulfidization episode. Iron disulfide minerals formed from the sulfur species of modern ground water have not been unequivocally identified.

Open-File Report↗
USGS1979

Fast-ice thickness and snow depth in relation to oil entrapment potential, Prudhoe Bay, Alaska

In winter, the undersurface of the sea ice on shallow arctic shelves acts upon the sea bed directly by contact and indirectly by influencing currents and turbulence. The under-ice surface would serve as a trap for pollutants such as oil and gas released from the sea bed. A knowledge of the morphology of the undersurface of the ice is a first step in understanding the sea-bed interactions and in evaluating the quantities, configuration, and dispersal patterns of sub-ice pollutants. Investigations show thicker sea-ice correlates with a thin snow cover and thin sea-ice underlies elongate snow ridges. In early May, 1978, the relationships between under-ice morphology, sea bed morphology, tidal currents, and variations in snow thickness were studied. At three sites representing three different environments--protected bay, deep, open lagoon, and narrow tidal channel--trenches were cut through the ice. The trenches were parallel and perpendicular to the sastrugi-sculptured northeast-southwest trending snow ridge pattern. Snow depth, ice thickness, and ice drafts were measured and an upward-directed side-scanning sonar was towed to examine the morphology of the under-ice surface in an area 100 m square. Snow depth and ice thickness vary about 30-40 cm and exhibit a negative correlation--thin ice coinciding with a thicker insulating snow cover. The areal snow and ice morphology patterns reinforced the correlation. Elongate ridge and trough patterns on the under-ice surface parallel the surface snow ridge patterns on wavelengths typically 10 m wide, yielding sub-ice voids of 25 to 47 x 10 3 m 3 /km 2 (600-1200 barrels per acre). Diving observations indicate a smaller set of depressions 5 cm or less in depth, oriented parallel to the ice crystal fabric, and an escape of sub-ice released air to the snow-ice interface. The results imply that there is a seasonal stability to the snow ridge pattern and that oil concentrations under the ice would be indicated by surficial snow morphology in the fast ice zone. Spreading directions would be enhanced in the elongate dimensions of the under-ice ridges and troughs, that is, upwind and downwind. In spring, gases will leak to the surface.

Alaska↗
USGS1981

Digital models of ground-water flow in the Cape Cod aquifer system, Massachusetts

The Cape Cod aquifer system was simulated with three-dimensional finite-difference ground-water-flow models. Five areas were modeled to provide tools that can be used to evaluate the hydrologic impacts of regional water development and waste disposal. The model boundaries were selected to represent the natural hydrologic boundaries of the aquifer. The boundary between fresh and saline ground water is treated as an interface along which there is no dispersion. The saline-water zone is treated as static (nonflowing). Comparisons of calculated and observed values of head, position of the boundary between fresh and saline water, and ground-water discharge at locations where data are available indicate that the simulated ground-water reservoirs generally agree with field conditions. Model analyses indicate that the total steady-state freshwater-flow rate through the five modeled areas is approximately 412 cubic feet per second.

Massachusetts↗
USGS1980

Hole-to-surface resistivity measurements at Salt Valley, Utah

Evaporites are an important potential medium for the storage of radioactive wastes. In order to ascertain the viability of a proposed waste isolation site, it is necessary to study its geology without extensive drilling that might destroy its structural integrity. Hole-to-surface and hole-to-hole geophysical measurements can be useful in supplementing geologic data obtained from a few drill holes and can be used to aid the interpretation of surface geophysical measurements. The study presented in this paper was conducted at Salt Valley, Utah to test the feasibility of using hole-to-surface direct-current resistivity measurements to detect geologic inhomogeneities in evaporites. These measurements show the following: (1) It is feasible to make hole-to-surface resistivity measurements over evaporites. However, near-surface steel casing can make it difficult to quantitatively analyze the field data with present interpretation techniques. Future investigations should include theoretical studies to solve interpretation problems when steel casing is in the hole and the mud is a high-conductivity brine. (2) A comparison of measurements made from the three different source drill holes shows that the halite acts as an electrical insulator and most of the current emitted from the source is contained in the caprock. (3) A comparison of measurements made parallel and perpendicular to the valley walls shows that there are more variations in the halitecaprock interface perpendicular than parallel to the axis of the Salt Valley anticline. (4) Structurally complex interbeds within the salt may cause differences in the current distribution measured at the surface from current sources buried at different depths. (5) Total field mapping would be more useful than the single-component data that were collected in this study.

Utah↗
USGS1981

Decentralized shared computers in the National Earthquake Hazards Reduction Program

The needs for computer analysis in the National Earthquake Program are varied, complex, and rapidly growing. Major sources of frustration have been the difficulty of keeping up with the required analysis, and the difficulties of sharing a wide variety of data and computer programs among several hundred researchers at dozens of institutions located throughout the U.S. A major effort is underway to create a similar computer environment running on many PDP 11/70 minicomputers located across the country that encourages widespread sharing of data and "software tools" without impeding the free flow of creative ideas in this research program. Large libraries of high-level tools are provided in a well documented manner. The tools can be readily combined into programs using a new interactive language, any compiled language, or, in many cases, the Shell command language of the UNIX** Timesharing System. New tools are easily written by any user. Major system tools provided include advanced general plotting programs and a relational indexed database. Extensions to the operating system include text overlays and an 830,000 baud graphics interface.

Open-File Report↗