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Detailed strati graphic and structural studies, performed in connection with the Nevada Nuclear Waste Storage Investigations program, have been in progress since 1978. The purpose of these studies is to characterize volcanic rocks underlying Yucca Mountain a volcanic highland situated along the western boundary of the Nevada Test Site in southern Nye county, Nevada. Core hole USW G-4 was cored from 41 ft (13 m) to a depth of 3,001 ft (915 m) at a location approximately 300 ft (91 m) southwest of the proposed site of an exploratory shaft that will be used for in situ studies of the geotechnical, geologic, and hydrologic characteristics of rock in the unsaturated zone to aid in evaluating the suitability of Yucca Mountain for storage of high-level nuclear wa'ste. The primary objectives of this study were to (1) verify that geologic conditions are similiar to those identified in nearby boreholes and (2) determine geologic and geophysical characteristics for use in the design and construction phases of the exploratory shaft. Strati graphic section in core hole USW G-4 is composed entirely of thick sequences of ash-flow tuff that are separated by fine-to coarse-grained ashfall tuff and tuffaceous sediments. All rocks are of Tertiary age and vary in composition from rhyolitic to quartz latitic. Major stratigraphic units include the Paintbrush Tuff, tuffaceous beds of Calico Hills, and Crater Flat Tuff. All four members of the Paintbrush Tuff were identified in USW G-4. In descending order, the members are the: Tiva Canyon, Yucca Mountain, Pah Canyon, and Topopah Spring. The Tiva Canyon and Topopah Spring Members are dominantly densely welded and devitrified, except for the basal part of the Tiva Canyon and upper and lower parts of the Topopah Spring where the rock is non-to partially welded and vitric. In contrast, the Yucca Mountain and Pah Canyon Members are entirely non-to partially welded and vitric. They represent the distal edges of ash-flow tuffs that thicken to the north and northwest. Plots of poles of fractures indicate that conspicuous fracture sets have orientations of (1) N. 22° E., 65° N.W. in the Tiva Canyon Member, (2) N. 12° W., 89-90° N.E. and S.W. in the Topopah Spring Member, and (3) N. 23° E., 45° N.W. and N. 50° E., 55° S.E. in the Crater Flat Tuff. Oriented fracture data obtained from television camera observations show no preferential strike of fractures in the Tiva Canyon Member and a wide range in the strike of fractures in the Topopah Spring Member, most of which strike between N. 30° W. and N. 60° E. Rock quality characteristics, as defined by the core index, indicate that greater amounts of broken core are associated with densely welded zones in the Tiva Canyon and Topopah Spring Members, and in zones that contain concentrations of shear fractures. Greater amounts of lost core and excessive hole enlargement are associated with vitric, non-to partially welded tuff. Geophysical logs from USW G-4 correlate well with logs from other drill holes at Yucca Mountain. Anomalous differences between t...

The Kabul Basin, which includes the city of Kabul, Afghanistan, with a population of approximately 4 million, has several Afghan, United States, and international military installations that depend on groundwater resources for a potable water supply. This study examined groundwater levels in the Kabul Basin from 2004 to 2012. Groundwater levels have increased slightly in rural areas of the Kabul Basin as a result of normal precipitation after the drought of the early 2000s. However, groundwater levels have decreased in the city of Kabul due to increasing water use in an area with limited recharge. The rate of groundwater-level decrease in the city is greater for the 2008-2012 period (1.5 meters per year (m/yr) on average) than for the 2004-2008 period (0-0.7 m/yr on average). The analysis, which is corroborated by groundwater-flow modeling and a non-governmental organization decisionsupport model, identified groundwater-level decreases and associated implications for groundwater sustainability in the city of Kabul. Military installations in the city of Kabul (the Central Kabul subbasin) are likely to face water management challenges resulting from long-term groundwater sustainability concerns, such as the potential drying of shallow water-supply wells. Installations in the northern part of the Kabul Basin may have fewer issues with longterm water sustainability. Groundwater-level monitoring and groundwater-flow simulation can be valuable tools for assessing groundwater management options to improve the sustainability of water resources in the Kabul Basin.

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