Hydrologic modeling of the Heihe watershed by DLBRM in Northwest China

Water shortage is a chronic problem in arid Northwest China.The rapid population growth and expanding urbanization as well as potential climate change impacts are likely to worsen the situation,threatening domestic,irrigation,and industrial supplies and even the survival of the ecosystems in Northwest China.This paper describes the preliminary work of adapting the Distributed Large Basin Runoff Model(DLBRM) to the Heihe watershed(the second largest inland river in arid Northwestern China,with a drainage area of 128,000 km2) for understanding distribution of glacial-snow melt,groundwater,surface runoff,and evapotranspi-ration,and for assessing hydrological impacts of climate change and glacial recession on water supply in the middle and lower reaches of the watershed.Preliminary simulation results show that the Qilian Mountain in the upper reach area produces most runoff in the Heihe watershed.The simulated daily river flows during the period of 1990-2000 indicate that the Heihe River dis-charges about 1×109 m3 of water from the middle reach(at Zhengyixia Station) to lower reach,with surface runoff and interflow contributing 51 and 49 percent respectively.The sandy lower soil zone in the middle reach has the highest evapotranspiration rate and also contributes nearly half of the river flow.Work underway focuses on the DLBRM model improvement and incorporation of the climate change and management scenarios to the hydrological simulations in the watershed.     

The geochemical nature of the Archean Ancient Gneiss Complex and Granodiorite Suite,Swaziland: a preliminary study

The Ancient Gneiss Complex (AGC) of Swaziland, an Archean gray gneiss complex, lies southeast and south of the Barberton greenstone belt and includes the most structurally complex and highly metamorphosed portions of the eastern Kaapvaal craton. The AGC is not precisely dated but apparently is older than 3.4 Ga.The AGC consists of three major units: (a) a bimodal suite of closely interlayered siliceous, low-K gneisses and metabasalt; (b) homogeneous tonalite gneiss; and (c) interlayered siliceous microcline gneiss, metabasalt, and minor metasedimentary rocks — termed the metamorphite suite. A geologically younger gabbro-diorite-tonalite-trondhjemite suite, the Granodiorite Suite, is spatially associated with the AGC and intrusive into it.The bimodal suite consists largely of two types of low-K siliceous gneiss: one has SiO₂ < 75%, Al₂O₃ > 14%, low Rb/Sr ratios, and depleted heavy rare earth elements (REE's); the other has SiO₂ > 75%, Al₂O₃ < 13%, high Rb/Sr ratios, and relatively abundant REE's except for negative Eu anomalies. The interlayered metabasalt ranges from komatiitic to tholeiitic compositions. Lenses of quartz monzonitic gneiss of K₂O/Na₂O close to 1 form a minor part of the bimodal suite. Tonalitic to trondhjemitic migmatite locally is abundant and has major-element abundances similar to those of non-migmatitic varieties.The siliceous gneisses of the metamorphic suite show low Al₂O, K₂O/Na₂O ratios of about 1, high Rb/Sr ratios, moderate REE abundances and negative Eu anomalies.K/Rb ratios of siliceous gneisses of the bimodal suite are very low (～130); of the tonalitic gneiss, low (～225); of the siliceous gneiss of the metamorphite suite, moderate (～300); and of the Granodiorite Suite, high (～400).Rocks of the AGC differ geochemically in several ways from the siliceous volcanic and hypabyssal rocks of the Upper Onverwacht Group and from the diapirs of tonalite and trondhjemite that intrude the Swaziland Group.     

Artificial muscle technology: physical principles and naval prospects

The increasing understanding of the advantages offered by fish and insect-like locomotion is creating a demand for muscle-like materials capable of mimicking nature's mechanisms. Actuator materials that employ voltage, field, light, or temperature driven dimensional changes to produce forces and displacements are suggesting new approaches to propulsion and maneuverability. Fundamental properties of these new materials are presented, and examples of potential undersea applications are examined in order to assist those involved in device design and in actuator research to evaluate the current status and the developing potential of these artificial muscle technologies. Technologies described are based on newly explored materials developed over the past decade, and also on older materials whose properties are not widely known. The materials are dielectric elastomers, ferroelectric polymers, liquid crystal elastomers, thermal and ferroelectric shape memory alloys, ionic polymer/metal composites, conducting polymers, and carbon nanotubes. Relative merits and challenges associated with the artificial muscle technologies are elucidated in two case studies. A summary table provides a quick guide to all technologies that are discussed.     

A Web-based system enabling the integration,analysis, and 3D sub-surface visualization of groundwater monitoring data and geological models

The 3D Water Chemistry Atlas is an intuitive, open source, Web-based system that enables the three-dimensional (3D) sub-surface visualization of ground water monitoring data, overlaid on the local geological model (formation and aquifer strata). This paper firstly describes the results of evaluating existing virtual globe technologies, which led to the decision to use the Cesium open source WebGL Virtual Globe and Map Engine as the underlying platform. Next it describes the backend database and search, filtering, browse and analysis tools that were developed to enable users to interactively explore the groundwater monitoring data and interpret it spatially and temporally relative to the local geological formations and aquifers via the Cesium interface. The result is an integrated 3D visualization system that enables environmental managers and regulators to assess groundwater conditions, identify inconsistencies in the data, manage impacts and risks and make more informed decisions about coal seam gas extraction, waste water extraction, and water reuse.     

Bio-treatment and water reuse as feasible treatment approaches for improving wastewater management during flotation of copper ores

Established and emerging technologies for treatment of flotation wastewaters are compared and discussed in the context of their applicability during the management of wastewaters from Cu–Co ores processing through flotation in the Katanga province of the Democratic Republic of Congo. The effects from water recycling on water quality and flotation performance are briefly presented in parallel. The ore processing schemes and the wastewater management practices at two operational concentrators are illustrated as study cases and their peculiarities outlined. A reference to a copper concentrator in a nearby Zambia is addressed for comparative purpose. Based on analysis of the findings, the clarification, bio-treatment inside the tailing ponds or the use of constructed wetlands as polishing stage prior to water reuse are suggested as feasible treatment approaches in view improving the management practice of flotation wastewaters during the dressing of copper ores in the Katanga province.     

Holocene valley-floor deposition and incision in a small drainage basin in western Colorado, USA

The valley floor of a 33.9 km² watershed in western Colorado experienced gradual sedimentation from before ∼ 6765 to ∼ 500 cal yr BP followed by deep incision, renewed aggradation, and secondary incision. In contrast, at least four terraces and widespread cut-and-fill architecture in the valley floor downstream indicate multiple episodes of incision and deposition occurred during the same time interval. The upper valley fill history is atypical compared to other drainages in the Colorado Plateau.One possible reason for these differences is that a bedrock canyon between the upper and lower valley prevented headward erosion from reaching the upper valley fill. Another possibility is that widespread, sand-rich, clay-poor lithologies in the upper drainage limited surface runoff and generally favored alluviation, whereas more clay-rich lithologies in the lower drainage resulted in increased surface runoff and more frequent incision. Twenty-two dates from valley fill charcoal indicate an approximate forest fire recurrence interval of several hundred years, similar to that from other studies in juniper-piñon woodlands. Results show that closely spaced vertical sampling of alluvium in headwater valleys where linkages between hillslope processes and fluvial activity are relatively direct can provide insight about the role of fires in alluvial chronologies of semi-arid watersheds.     

Examination of core samples from the Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope: Effects of retrieval and preservation

Collecting and preserving undamaged core samples containing gas hydrates from depth is difficult because of the pressure and temperature changes encountered upon retrieval. Hydrate-bearing core samples were collected at the BPXA-DOE-USGS Mount Elbert Gas Hydrate Stratigraphic Test Well in February 2007. Coring was performed while using a custom oil-based drilling mud, and the cores were retrieved by a wireline. The samples were characterized and subsampled at the surface under ambient winter arctic conditions. Samples thought to be hydrate bearing were preserved either by immersion in liquid nitrogen (LN), or by storage under methane pressure at ambient arctic conditions, and later depressurized and immersed in LN. Eleven core samples from hydrate-bearing zones were scanned using x-ray computed tomography to examine core structure and homogeneity. Features observed include radial fractures, spalling-type fractures, and reduced density near the periphery. These features were induced during sample collection, handling, and preservation. Isotopic analysis of the methane from hydrate in an initially LN-preserved core and a pressure-preserved core indicate that secondary hydrate formation occurred throughout the pressurized core, whereas none occurred in the LN-preserved core, however no hydrate was found near the periphery of the LN-preserved core. To replicate some aspects of the preservation methods, natural and laboratory-made saturated porous media samples were frozen in a variety of ways, with radial fractures observed in some LN-frozen sands, and needle-like ice crystals forming in slowly frozen clay-rich sediments. Suggestions for hydrate-bearing core preservation are presented.     

Zero graffiti for a beautiful city: the cultural politics of urban space in San Francisco

San Francisco, like many cities in the United States and across the world, has an official zero-tolerance policy on graffiti. In this article, we examine the academic literature concerned with graffiti and then present a case study of zero-tolerance abatement policies in San Francisco. Our analysis yields three main findings. First, zero-tolerance policy stimulates an anti-graffiti industry with vested interest in perpetuating an endless war for control of public space. Second, zero tolerance may generate an unintended result—the proliferation of tags and other forms of graffiti that people tend to dislike the most. Third, we find little evidence that the general public shares the same desire for zero tolerance as the San Francisco Government. Ultimately, we believe that more nuanced readings of graffiti allow greater numbers of people to make sensible, local, place-specific policies regarding graffiti.     

Estimating sea-level extremes under conditions of uncertain sea-level rise

Estimation of expected extremes, using combinations of observations and model simulations, is common practice. Many techniques assume that the background statistics are stationary and that the resulting estimates may be used satisfactorily for any time in the future. We are now however in a period of climate change, during which both average values and statistical distributions may change in time. The situation is further complicated by the considerable uncertainty which accompanies the projections of such future change. Any useful technique for the assessment of future risk should combine our knowledge of the present, our best estimate of how the world will change, and the uncertainty in both. A method of combining observations of present sea-level extremes with the (uncertain) projections of sea-level rise during the 21st century is described, using Australian data as an example. The technique makes the assumption that the change of flooding extremes during the 21st century will be dominated by the rise in mean sea level and that the effect of changes in the variability about the mean will be relatively small. The results give engineers, planners and policymakers a way of estimating the probability that a given sea level will be exceeded during any prescribed period during the present century.