Abstract: Alpine areas pose challenges for many existing remote sensing methods for snow depth retrieval, thus leading to uncertainty in water forecasting and budgeting. Herein, we present the results of a field campaign conducted in Tasmania, Australia in 2013 from which estimates of snow depth were derived using a low-cost photogrammetric approach on-board a micro unmanned aircraft system (UAS). Using commercial off-the-shelf (COTS) sensors mounted on a multi-rotor UAS and photogrammetric image processing techniques, the results demonstrate that snow depth can be accurately retrieved by differencing two surface models corresponding to the snow-free and snow-covered scenes, respectively. In addition to accurate snow depth retrieval, we show that high-resolution (50 cm) spatially continuous snow depth maps can be created using this methodology. Two types of photogrammetric bundle adjustment (BA) routines are implemented in this study to determine the optimal estimates of sensor position and orientation, in addition to 3D scene information; conventional BA (which relies on measured ground control points) and direct BA (which does not require ground control points). Error sources that affect the accuracy of the BA and subsequent snow depth reconstruction are discussed. The results indicate the UAS is capable of providing high-resolution and high-accuracy (<10 cm) estimates of snow depth over a small alpine area (~0.7 ha) with significant snow accumulation (depths greater than one meter) at a fraction of the cost of full-size aerial survey approaches. The RMSE of estimated snow depths using the conventional BA approach is 9.6 cm, whereas the direct BA is characterized by larger error, with an RMSE of 18.4 cm. If a simple affine transformation is applied to the point cloud derived from the direct BA, the overall RMSE is reduced to 8.8 cm RMSE.
Abstract: Eocene lakebed sediments at Stonerose Interpretive Center in Republic, Washington, USA are one of the most important Cenozoic fossil sites in North America, having gained international attention because of the abundance and diversity of plant, insect, and fish fossils. This report describes the first detailed geologic investigation of this unusual lagerstätten. Strata are gradationally divided into three units: Siliceous shale that originated as diatomite, overlain by laminated mudstone, which is in turn overlain by massive beds of lithic sandstone. The sedimentary sequence records topographic and hydrologic changes that caused a deep lake to become progressively filled with volcaniclastic detritus from earlier volcanic episodes. The location of the ancient lake within an active graben suggests that displacements along the boundary faults were the most likely trigger for changes in depositional processes.
Abstract: A comprehensive classification of primitive achondrites is difficult due to the high compositional and textural variability and the low number of samples available. Besides oxygen isotopic analysis, other minerochemical and textural parameters may provide a useful tool to solve taxonomic and genetic problems related to these achondrites. The results of a detailed modal, textural and minerochemical analysis of a set of primitive achondrites are presented and compared with literature data. All the samples show an extremely variable modal composition among both silicate and opaque phases. A general trend of troilite depletion vs. silicate fraction enrichment has been observed, with differences among coarse-grained and fine-grained meteorites. In regard to the mineral chemistry, olivine shows marked differences between the acapulcoite-lodranite and winonaite groups, while a compositional equilibrium between matrix and chondrules for both groups, probably due to the scarce influence of metamorphic grade on this phase, was observed. The analysis of Cr and Mn in clinopyroxene revealed two separate clusters for the acapulcoite/lodranite and winonaite groups, while the analysis of the reduction state highlighted three separate clusters. An estimate of equilibrium temperatures for the acapulcoite-lodranite and winonaite groups is provided. Finally, proposals regarding the genetic processes of these groups are discussed.
Abstract: The violent storms of 22–30 November 2014, resulted in flash floods and wadi floods (rivers) in large parts of Southern Morocco, at the foot of the Atlas Mountains. The Guelmim area was the most affected part with at least 32 fatalities and damages due to inundations. The flooding hazard in the Guelmim region initiated this study in order to investigate the use of remote sensing and geographic information system (GIS) for the detection and identification of areas most likely to be flooded in the future again due to their morphologic properties during similar weather conditions. By combining morphometric analysis and visual interpretation based on Landsat 8 satellite data and derived images such as water index (NDWI) images, areas with relatively higher soil moisture and recently deposited sediments were identified. The resulting maps of weighted overlay procedures, aggregating causal, morphometric factors influencing the susceptibility to flooding (lowest height levels, flattest areas), allowed for the distinguishing of areas with higher, medium and lower susceptibility to flooding. Thus, GIS and remote sensing tools contribut to the recognition and mapping of areas and infrastructure prone to flooding in the Guelmim area.
Abstract: Global Positioning System (GPS) and geodetic control networks are used today for analyzing and monitoring time-dependent crustal deformations, providing a series of accurate positional measurements to deliver information on positional changes and deformations that have occurred. Still, such networks present a low-resolution dispersal of positional measures, and do not take into account various physical constraints that affect the terrain’s seismic behavior. An alternative form of spatio-temporal infrastructure that is feasible and practical to establish might involve the use of Digital Terrain Model (DTM) databases. These databases use higher positional resolutions, and are exhibiting an increasing level of positional and height accuracy. Still, when comparing temporal DTMs, the separation of actual physical phenomena from data-related ambiguities is essential in the framework of spatio-temporal analysis. This paper proposes the use of a hierarchical co-modeling of different DTM databases for the task of landform monitoring. Analyses showed promising results, pointing to the feasibility of the proposed methodology in monitoring and quantifying topographic-related spatio-temporal phenomena, such as landslides and change detection, thus facilitating a reliable and precise landform monitoring and warning framework for geomorphodynamic analyses.
Abstract: Mercury concentrations in the environment (river sediments and fish) and in the hair of artisanal gold miners and inhabitants of the Gorontalo Utara Regency were determined in order to understand the status of contamination, sources and their impacts on human health. Mercury concentrations in the sediments along the Wubudu and Anggrek rivers are already above the tolerable level declared safe by the World Health Organization (WHO). Meanwhile, commonly consumed fish, such as snapper, have mercury levels above the threshold limit (0.5 μg/g). The mean mercury concentrations in the hair of a group of inhabitants from Anggrek and Sumalata are higher than those in hair from control group (the inhabitants of Monano, Tolinggula and Kwandang). The mean mercury concentration in the hair of female inhabitants is higher than that in the hair of male inhabitants in each group. Neurological examinations were performed on 44 participants of artisanal and small-scale gold mining (ASGM) miners and inhabitants of Anggrek and Sumalata. From the 12 investigated symptoms, four common symptoms were already observed among the participants, namely, bluish gums, Babinski reflex, labial reflex and tremor.