Paradise Threatened: Land Use and Erosion on St. John, US Virgin Islands

2 /yr, respectively. Geomorphic evidence indicates that plantation agriculture during the 18th and 19th centuries did not cause severe erosion. Since about 1950 there has been rapid growth in roads and development due to increasing tourism and second-home development. Our field investigations identified the approximately 50 km of unpaved roads as the primary source of anthropogenic sediment. Field measurements of the road network in two catchments led to the development of a vector-based GIS model to predict road surface erosion and sediment delivery. We estimate that road erosion has caused at least a fourfold increase in island-wide sediment yields and that current sedimentation rates are unprecedented. Paving the dirt roads and implementing standard sediment control practices can greatly reduce current sediment yields and possible adverse effects on the marine ecosystems surrounding St. John.     

OPTIMIZATION MODELING OF A NEW FACILITY FOR THE CALIFORNIA STATE WATER PROJECT1

ABSTRACT: A non-linear optimization model is applied to the California State Water Project (SWP) and portions of the Central Valley Project (CVP). The model accounts for the major hydrologic, regulatory, and operational features of both projects. The model maximizes long-term SWP yields over a 70-year period, using a quarterly time step. The potential for increased yield associated with a proposed facility improvement is evaluated with the model. The proposed facility is an extension of the Folsom-South Canal, which would allow water to be conveyed from the American River below Folsom Reservoir into New Melones Reservoir on the Stanislaus River or into the California Aqueduct. Model results indicate that extension of the Folsom-South Canal has the potential to increase SWP yields by 13 percent.     

Job level risk assessment using task level strain index scores: a pilot study.

This paper explores 2 methods of modifying the Strain Index (SI) to assess the ergonomic risk of multi-task jobs. Twenty-eight automotive jobs (15 cases and 13 controls) were studied. The first method is based on the maximum task SI score, and the second method is modeled on the NIOSH Composite Lifting Index (CLI) algorithm, named cumulative assessment of risk to the distal upper extremity (CARD). Significant odds ratios of 11 (CI 1.7-69) and 24 (CI 2.4-240) were obtained using the modified maximum task and CARD, respectively. This indicates that modification of the SI may be useful in determining the risk of distal upper extremity injury associated with a multi-task job.     

Coupled reservoir-geomechanical analysis of CO2 injection and ground deformations at In Salah,Algeria

In Salah Gas Project in Algeria has been injecting 0.5–1 million tonnes CO₂ per year over the past 5 years into a water-filled strata at a depth of about 1800–1900 m. Unlike most CO₂ storage sites, the permeability of the storage formation is relatively low and comparatively thin with a thickness of about 20 m. To ensure adequate CO₂ flow-rates across the low-permeability sand-face, the In Salah Gas Project decided to use long-reach (about 1–1.5 km) horizontal injection wells. In an ongoing research project we use field data and coupled reservoir-geomechanical numerical modeling to assess the effectiveness of this approach and to investigate monitoring techniques to evaluate the performance of a CO₂ injection operation in relatively low-permeability formations. Among the field data used are ground surface deformations evaluated from recently acquired satellite-based inferrometry (InSAR). The InSAR data shows a surface uplift on the order of 5 mm per year above active CO₂ injection wells and the uplift pattern extends several km from the injection wells. In this paper we use the observed surface uplift to constrain our coupled reservoir-geomechanical model and conduct sensitivity studies to investigate potential causes and mechanisms of the observed uplift. The results of our analysis indicate that most of the observed uplift magnitude can be explained by pressure-induced, poro-elastic expansion of the 20-m-thick injection zone, but there could also be a significant contribution from pressure-induced deformations within a 100-m-thick zone of shaly sands immediately above the injection zone.     

Sulfur Dioxide and Material Damage

Whereas most estimates of material damage are based on industrial surveys, the estimates produced in this study were derived from material damage experiments and ambient air quality data. Air quality data on SO₂ were obtained from 200 or more monitoring sites primarily located in heavily populated or polluted areas. Material threshold damage function data were then compared with SO₂ levels, and an estimate of losses, as reflected in increased maintenance and replacement costs, was determined. Estimates of the total stock of various materials in use were derived from census and industry data and allocated geographically according to population. A substantial decrease in the ambient SO₂ levels, particularly in larger urban areas, has occurred during the past five years. From 1968 to 1972, the estimated amount of material damage from SO₂ in the U. S. decreased from $900 million/yr to less than $100 million. During this period, the estimated percentage of man made materials exposed to SO₂ levels exceeding the proposed secondary annual average standard (60 μg/m³) and primary annual average standard (80 μg/m³) in the U. S. fell respectively, from 20% to less than 5% and from more than 10% to less than 1%. Most of the present loss is attributed to corrosion damage of metallic surfaces that are normally exposed to the ambient environment.     

Climate change,risk perception,and protection motivation among high-altitude residents of the Mt. Everest region in Nepal

Mountain ecosystems are considered vulnerable to early impacts of climate change. Whether and how local residents of these areas perceive these changes, however, remain under-studied questions. By conducting a household survey in the Khumbu region of Nepal, this study assessed local residents’ experience-based perception of changes in climate trends and patterns, perceived risk, and attitudes towards climate issues. Multivariate cluster analysis based on residents’ climate change beliefs revealed three segments: “Cautious,” “Disengaged,” and “Alarmed.” A comparison of these segments along key psychosocial constructs of Protection Motivation Theory (PMT) revealed significant inter-segment differences in residents’ perception of severity, vulnerability, response efficacy, self-efficacy, and response cost associated with engaging in mitigating behavior. Results shed light on how residents of high elevation areas that are considered to be exposed to early impacts of climate change perceive the risk and intend to respond. These findings could also assist stakeholders working in other similar mountain ecosystems in understanding vulnerability and in working towards climate readiness.Electronic supplementary materialThe online version of this article (10.1007/s13280-020-01369-x) contains supplementary material, which is available to authorized users.     

A metal-free composite photocatalyst of graphene quantum dots deposited on red phosphorus

A simple approach to enhance the photocatalytic activity of red phosphorus(P) was developed.A mechanical ball milling method was applied to reduce the size of red P and to deposit graphene quantum dots onto red P. The product was characterized by scanning electron microscopy, transmission electron microscopy, contact angle measurements, zeta-potential measurements, X-ray diffraction and UV–vis absorption spectroscopy. The product exhibited high visible-light-driven photocatalytic performance in the photodegradation of rhodamine B.     

The availability of primary nickel from the market economy countries

The US Bureau of Mines has determined the potential availability of nickel from 36 deposits or districts in 16 market economy countries (MECs). More than 95% of production in MECs was analysed. The study indicates the quantity of nickel available in resources and potential annual production at net production costs and on a total cost basis with a 0% and a 10% discounted cash flow rate of return (DCFROR). The properties included in this study contain approximately 33 million tonnes of recoverable nickel. About 26 million tonnes of nickel is potentially recoverable from nickel laterite deposits, of which 4.5 million tonnes can be produced at $2.50/lb or less with a 0% DCFROR. Approximately 7 million tonnes of nickel is potentially recoverable from nickel sulphide deposits of which about 6.3 million tonnes could be produced at $2.50/lb or less at a 0% DCFROR. Sensitivity studies indicate that the total cost of producing nickel from laterite deposits is most sensitive to increases in energy costs, and that the total costs of producing nickel from sulphide deposits is most sensitive to increases in labour costs and by changes in byproduct revenues.     

A COMPARISON OF STREAMFLOW GENERATION MODELS FOR RESERVOIR CAPACITY-YIELD ANALYSIS1

ABSTRACT: An analysis of four streamflow generation schemes for the use in the estimation of the required conservation storage for a single reservoir is presented. The comparison of the generating schemes should aid in the selection of an appropriate model type for the reservoir sizing problem. The streamflow generation models are compared using two criteria. The first comparison is between the statistics of the generated streamflow sequences and the corresponding statistics from the historical record. The second evaluation compares the median reservoir size determined by each model with the required storage based on the historical flow sequence. The results of a comparative analysis for monthly streamflow data for the Rzav River in Yugoslavia are presented and discussed. The results indicate that both evaluation criteria are required to discriminate between the various options.