Giant landslide deposits and the modalities of their removal by fluvial sediment export in the central Himalayas.

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Surface Lagrangian Remeshing: A new tool for studying long term evolution of continental lithosphere from 2D numerical modelling

International audienceIn this paper we present a new local remeshing algorithm that is dedicated to the problem of erosion in finite element models whose grid follows the movement of the free surface. The method, which we name Surface Lagrangian Remeshing (SLR), is adapted to 2D Lagrangian models which couple surface erosion with deformation of Earth materials. The remeshing procedure preserves nodes defining the surface submitted to erosion and removes nodes belonging to surface elements whose internal angles or area is critically low. This algorithm is ideally suited to track long term surface evolution. To validate the method we perform a set of numerical tests, using triangular finite elements, which compare the results obtained with the SLR algorithm with global remeshing and with analytical results. The results show good agreements with analytical solutions. Interpolation errors associated with remeshing are generated locally and numerical diffusion is restricted to the remeshed domain itself. In addition this method is computationally costless compared to classical global remeshing algorithm. We propose to couple the SLR method with the Dynamical Lagrangian Remeshing (DLR) algorithm to enable local remeshing only of Lagrangian models coupling large deformation of Earth materials with large erosion

Late Cenozoic 10Be paleo-erosion rates of the Central Himalayan Range, measured along a new Siwaliks section in Northern India.

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Competitive Energy Options for Pennsylvania

Pennsylvania’s commercial and industrial customers are concerned that electricity prices in the Commonwealth put them at a disadvantage with respect to competitors in nearby states. Retail rates (averaged over all rate classes) in three neighboring states increased by 13 to 118% when rate caps expired in those states. At the end of 2010, rate caps will have expired throughout Pennsylvania. Data compiled by the Industrial Energy Consumers of Pennsylvania indicate that load serving entities in the Commonwealth expect rate increases from 30 to 75 percent when the caps are lifted. The Pennsylvania Office of the Small Business Advocate reports that commercial customers have similar expectations. This study examines the electricity prices offered to commercial and industrial customers and evaluates options for competitive electricity prices for commercial and industrial customers.</p

The U.S. Electric Power Sector and Climate Change Mitigation

Measured by environmental impact and economic importance, the electricity industry is one of the most important sectors of the American economy. The generation of electricity is responsible for 38 percent of all U.S. carbon dioxide (CO2) emissions and one third of all U.S. greenhouse gas (GHG) emissions. This sector is the largest single source of these emissions. It is also the largest source of sulfur dioxide (SO2), oxides of nitrogen (NOX), small particles, and other air pollutants. At the same time, electricity is critical to the U.S. economy. Recent annual national expenditures on electricity totaled $250 billion—making the electricity sector’s share of overall GDP larger than that of the automobile manufacturing industry and roughly equal in magnitude to that of the telecommunications industry. Expenditures alone, however, understate the importance of electricity to the U.S. economy. Nearly every aspect of productive activity and daily life in a modern economy depends on electricity for which there is, in many cases, no close substitute. As the most desirable form of energy for many uses, electricity use has grown faster than GDP. The Internet and computers would not operate without very reliable, high-quality electricity. Electricity also plays a major role in delivering modern comforts and easing household tasks, from running heating and cooling systems to washing clothes and dishes. It plays an even more important role in the commercial, manufacturing, and agricultural sectors, where it provides lighting and powers a variety of machines. In short, it is hard to imagine a modern economy functioning without large amounts of reliable, high-quality electricity.</p

Climate change and erosion: view from the Himalaya

International audienceLate Cenozoic climate cooling and glaciations left evidence worldwide in mountains and may have inducedan increase of erosion rates (accelerated erosion). While this postulate may be supported for the high andmid-latitude regions by low-temperature thermochronometry, the links between climate and erosion remainhighly controversial for the sub-tropical regions, particularly for the Himalaya. On the one hand, bedrock low-temperature thermochronometry was interpreted as pointing to accelerated erosion in some parts of theHimalaya. On the other hand, detrital thermochronometry may point to relatively stable erosion rates sincethe middle Miocene, suggesting that climate change played a minor role in the control of erosion. Thesedifferences may originate from inherent methodological biases, but also from the lack of data in someregions. Therefore, it appears difficult to resolve the links between climate change and erosion in theHimalaya without a complementary approach.Here we discuss about new terrestrial 10Be paleo-concentrations obtained from the quartz fractions of bothsediments cored within the Bengal fan, and sediments sampled along a new Siwalik (frontal Himalaya)section. 10Be is produced within rocks at the earth's surface by exposure to cosmic rays. 10Be extracted fromsediments integrates erosion from the contributing watershed over millennial timescales (for the Himalaya).Commonly applied to modern sediments, 10Be also allows to measure past erosion when applied to detritalseries and complements detrital thermochronometry, which integrates erosion over longer timescales.The Bengal fan consists of sandy-rich turbidites integrating sediments from the Brahmaputra and Gangawatersheds, i.e. a region covering ~2/3 of the Himalaya. IODP Expeditions 353 and 354 recently drilled onesite at 14°N and a transect of sites at 8°N in the fan. The cores were dated by magnetostratigraphy andbiostratigraphy. Additionally, a new continental section was investigated in the central Himalaya. The Siwalikmolasses consist of erosion products accumulated in the Ganga plain during the late Cenozoic, and presentlyexposed at the front of the range by thin skin tectonics. Located in front of the Narayani-Gandak fan apex,South of the Chiwan Dun (Bihar, northern India), the new section presents almost continuous sandy to finefractions of sedimentary rocks. This section was chosen since the Narayani watershed is one of the majorwatersheds in Central Himalaya, and is extensively documented in terms of structural geology,geomorphology, geochemistry or erosion rates. The new section was dated by magnetostratigraphy.Viewed from the Bengal fan, the 10Be-derived erosion rates, inversely correlated to 10Be concentrations, showa relatively constant average value since 6 Ma onwards, and roughly similar to modern erosion rates. Inparticular, there is no dramatic increase of erosion rates at the Quaternary transition. The 10Be concentrationsfrom the new Siwalik section similarly show a relatively stable average since 5 Ma onwards. However, bothdatasets present short-term variations of high amplitude since the late Miocene. The interpretation of thesevariations can be discussed in view of independent data on tectonic or climatic changes in the Himalaya

A Cautionary Tale: US Electricity Sector Reform

<p>In the 1970s, the US electric utility industry was faced with rising costs and sluggish demand. Efforts at lowering costs and revitalising the industry through competition have largely been disappointing. Consumers have not seen prices fall, except where regulators have intervened. The merchant sector has suffered a financial crisis, hurting competition in both wholesale and retail markets. Advocates for deregulation assert that minor changes to market rules and regulations will yield the benefits promised. We argue that things are not so simple. Successful deregulation requires markets to be competitive and complete, neither of which is true in the US. Creating competitive markets is not impossible, but doing so imposes costs on the system which may outweigh the benefits of deregulation.</p

Steady erosion rates in the Himalayas through late Cenozoic climatic changes

International audienceSediment accumulation rates and thermal trackers suggest a substantial and global increase in erosion rates over the last few million years. That increase is commonly associated with the impact of the Northern Hemisphere glaciation, but methodological biases have led researchers to debate this hypothesis. Here, we test whether Himalayan erosion rates increased by measuring beryllium 10 (10Be) in the sediment of the Bengal Bay seabed. Sediment originated from rocks that produced 10Be under the impact of cosmic rays during erosion near surface. Thus, the 10Be concentrations tell erosion rates. The 10Be concentration of the Bengal Bay sediment depends on the contributions of the Ganga and Brahmaputra Rivers. Their sediments have distinct 10Be concentrations because of distinct elevations and erosion in their drainage basins. Variable contributions could thus complicate erosion rate calculation. We traced these contributions by a provenance study using the Sr and Nd isotopic sediment compositions. Within uncertainties of ±30%, our reconstructed past erosion rates show no long-term increase for the last six million years. This stability suggests that climatic changes during the late Cenozoic have an undetectable impact on the erosion patterns in the Himalayas, at least on the ten-thousand to million-year timescales accounted for by our dataset

Limited impact of Quaternary glaciations on denudation rates in Central Asia

International audienceBecause of its essential role in coupling climate and tectonics, denudation is a key parameter when constraining the history of Earth’s surface. This is particularly true at the Pliocene-Pleistocene transition, and the potential impact of the onset of Quaternary glaciations remains strongly debated. In the present study, we measured in situ cosmogenic 10Be within continuous late Cenozoic sedimentary sections that had already been dated using magnetostratigraphy. The new data were obtained from four sedimentary basins in the northern and southern Tianshan range (Central Asia). We first thoroughly discuss how in situ cosmogenic 10Be concentrations can be corrected for radioactive decay and for the contribution of postdepositional cosmogenic accumulation to derive the paleo–denudation rates. Our analysis shows that, in the four sedimentary records, the potential bias remains low enough to consider the derived denudation rates reliable. The four records, although likely influenced by local particularities due to lithological heterogeneity and local tectonics, display similar trends of continuously increasing denudation between ca. 9 Ma and the present. These rates have remained relatively high but steady since 4 Ma, ∼1.5 m.y. before the onset of the Quaternary glacial cycles. Though the rejuvenation of the Tianshan range since 11 Ma may explain most of the progressive increase (×5) in denudation, our data suggest that the Quaternary glaciations had only a limited impact on denudation in the Tianshan. Our data, however, indicate an increase in the spatial and high-frequency variability (<1 m.y.) of the denudation rates between 3 and 1 Ma. This may correspond to a transient readjustment of the landscape in response to the onset of Quaternary glacial cycles

An Engineering-Economic Analysis of Syngas Storage

We examined whether an IGCC facility that operates its gasifier continuously but stores the syngas and produces electricity only when daily prices are high may be more profitable than an IGCC facility with no syngas storage. We consider reference plants under a range of economic assumptions, both with and without carbon dioxide capture and sequestration. The goal of this study was to do an initial examination of whether storing syngas can increase the profitability of IGCC plants, rather than to perform a plant design.</p