GNSS satellite-based augmentation systems for Australia

We provided an overview of various satellite-based augmentation systems (SBAS) options for augmented GNSS services in Australia, and potentially New Zealand, with the aim to tease out key similarities and differences in their augmentation capabilities. SBAS can technically be classified into two user categories, namely SBAS for aviation and “non-aviation” SBAS. Aviation SBAS is an International Civil Aviation Organization (ICAO) certified civil aviation safety-critical system providing wide-area GNSS augmentation by broadcasting augmentation information using geostationary satellites. The primary aim was to improve integrity, availability and accuracy of basic GNSS signals for aircraft navigation. On the other hand, “non-aviation” SBAS support numerous GNSS applications using positioning techniques such as wide-area differential-GNSS (DGNSS) and precise point positioning (PPP). These services mainly focus on delivering high-accuracy positioning solutions and guaranteed levels of availability, and integrity remains secondary considerations. Next-generation GNSS satellites capable of transmitting augmentation signals in the L1, L5 and L6 frequency bands will also be explored. These augmentation signals have the data capacity to deliver a range of augmentation services such as SBAS, wide-area DGNSS and PPP, to meet the demands of various industry sectors. In addition, there are well-developed plans to put in place next-generation dual-frequency multi-constellation SBAS for aviation. Multi-constellation GNSS increases robustness against potential degradation of core satellite constellations and extends the service coverage area. It is expected that next-generation SBAS and GNSS will improve accuracy, integrity, availability and continuity of GNSS performance.     

New developments in water efficiency

1Water LossInitiativesUnaccounted-for water(or unbilled water)has beenreceiving newscrutiny at both the state and nationallevels.For years,water conservationeffortsin Europehave emphasized reduction in water loss to a muchgreater extent thaninthe United S…     

Hyper‐planning Jakarta: The Great Garuda and planning the global spectacle

After a major flood in Jakarta in 2007, the government of Indonesia partnered with a consortium of Dutch engineers and designers to produce a solution. In 2013, this consortium proposed a plan for the Great Garuda, a megaproject that combined a deep seawall and private real estate, both in an archipelago of reclaimed islands that would be shaped like the mythical garuda eagle, Indonesia's national symbol. Despite a range of infeasibilities and opposition, the Great Garuda became the most prominent vision for the city's future. This article argues that the promotion of the Great Garuda was a process of ‘hyper‐planning’, which projected the city as a national triumph and a global spectacle. The plan served the political objective of creating the mere possibility of a ‘new Jakarta’ apart from the perceived chaos of the current capital. Further, the plan functioned as a performative object through its iconic imagery and its circulations. The process of hyper‐planning simultaneously projected a future of urban success, but also displaced the contingencies of the future to the private sector, beyond the purview of the state.     

Streamflow and suspended sediment yield following the 2000 Bobcat fire,Colorado

Postfire runoff and erosion are a concern, and more data are needed on the effects of wildfire at the watershed‐scale, especially in the Colorado Front Range. The goal of this study was to characterize and compare the streamflow and suspended sediment yield response of two watersheds (Bobcat Gulch and Jug Gulch) after the 2000 Bobcat fire. Bobcat Gulch had several erosion control treatments applied after the fire, including aerial seeding, contour log felling, mulching, and straw wattles. Jug Gulch was partially seeded. Study objectives were to: (1) measure precipitation, streamflow, and sediment yields; (2) assess the effect of rainfall intensity on peak discharges, storm runoff, and sediment yields; (3) evaluate short‐term hydrologic recovery. Two months after the fire, a storm with a maximum 30 min rainfall intensity I₃₀ of 42 mm h^?1 generated a peak discharge of 3900 l s^?1 km^?2 in Bobcat Gulch. The same storm produced less than 5 l s^?1 km^?2 in Jug Gulch, due to less rainfall and the low watershed response. In the second summer, storms with, I₃₀ of 23 mm h^?1 and 32 mm h^?1 generated peak discharges of 1100 l s^?1 km^?2 and 1700 l s^?1 km^?2 in the treated and untreated watersheds respectively. Maximum water yield efficiencies were 10% and 17% respectively, but 18 of the 23 storms returned ≤2% of the rainfall as runoff, effectively obscuring interpretation of the erosion control treatments. I₃₀ explained 86% of the variability in peak discharges, 74% of the variability in storm runoff, and >80% of the variability in sediment yields. Maximum single‐storm sediment yields in the second summer were 370 kg ha^?1 in the treated watershed and 950 kg ha^?1 in the untreated watershed. Copyright © 2005 John Wiley & Sons, Ltd.     

The K-band Hubble diagram of submillimetre galaxies and hyperluminous galaxies

We present the K -band Hubble diagrams ( K – z relations) of submillimetre-selected galaxies and hyperluminous galaxies (HLIRGs). We report the discovery of a remarkably tight K – z relation of HLIRGs, indistinguishable from that of the most luminous radio galaxies. Like radio galaxies, the HLIRG K – z relation at   z ≲ 3  is consistent with a passively evolving ∼3 L _* instantaneous starburst starting from a redshift of   z ∼ 10  . In contrast, many submillimetre-selected galaxies are ≳2 mag fainter, and the population has a much larger dispersion. We argue that dust obscuration and/or a larger mass range may be responsible for this scatter. The galaxies so far proved to be hyperluminous may have been biased towards higher AGN bolometric contributions than submillimetre-selected galaxies due to the 60-μm selection of some, so the location on the K – z relation may be related to the presence of the most massive active galactic nucleus. Alternatively, a particular host galaxy mass range may be responsible for both extreme star formation and the most massive active nuclei.     

Modelling palaeosol preservation in aeolian dunes

In some of the world's desert and desert‐marginal areas (e.g. Simpson/Strzelecki, Australia) dunefields preserve well‐developed palaeosols, whereas in other regions with broadly similar climatic regimes and topography (e.g. southwest Kalahari), the dunes are characterized by very poorly developed internal stratigraphy. It has been postulated that dunes such as those in the Kalahari may never have had conditions conducive to soil formation, or that soils once formed but any evidence of palaeosols has been lost due to reworking. This study develops and applies a one‐dimensional numerical model to simulate dune development, soil formation and soil preservation. Variables in the model allowed experimentation on the influence of sediment supply, the time taken for soil to form, and the additional resistance to erosion offered by the soil. Reduced sediment supply plays a vital role in landscape development during periods of initial pedogenesis. Although re‐exhumed palaeosols influence sediment supply, the effect is minimal. Although under almost all parameterized conditions more than half (and up to 80‐90%) of those soils initially formed are lost due to reworking, evidence of their past formation remains in the large majority of profiles, and the dominant factor in controlling the preservation of palaeosols is the frequency of their formation. The implication is that where dunes are found without palaeosols, the most likely (albeit not certain) inference is that they have never formed. Counter‐intuitively, the limited sediment supply means their additional resistance to erosion becomes almost inconsequential to their preservation, at least until the unit approaches complete invulnerability. Short chronostratigraphic hiatuses around palaeosols are normal, and although long gaps can occur, they are extremely infrequent. Where such gaps are observed in field studies, external forcing factors (e.g. climatic or environmental changes) are implied, as they are highly unlikely to result from stochastic net preservation. Copyright © 2014 John Wiley & Sons, Ltd.     

Contaminant concentrations in sport fish from San Francisco Bay, 1997

In 1997, seven sport fish species were sampled from seven popular fishing areas in San Francisco Bay. Mercury exceeded a human health screening value in 44 of 84 (52%) samples. All collected samples of leopard shark and striped bass exceeded the mercury screening value of 0.23 microg/g wet weight. PCBs exceeded the screening value in 51 of 72 (71%) samples. DDT, chlordane, and dieldrin, had lower numbers of samples above screening values: 16 of 72 (22%) for DDT, 11 of 72 (15%) for chlordanes, and 27 of 72 (37%) for dieldrin. Concentrations of PCBs and other trace organics were highest in white croaker and shiner surfperch, the two species with the highest fat content in their muscle tissue. Fish from one location, Oakland Harbor, had significantly elevated wet weight concentrations of mercury, PCBs, DDTs, and chlordanes compared to other locations. Removal of skin from white croaker fillets reduced lipid concentrations by 27-49% and concentrations of trace organics by 33-40%.