Measuring channel planform change from image time series: A generalizable,spatially distributed,probabilistic method for quantifying uncertainty

Channels change in response to natural or anthropogenic fluctuations in streamflow and/or sediment supply and measurements of channel change are critical to many river management applications. Whereas repeated field surveys are costly and time-consuming, remote sensing can be used to detect channel change at multiple temporal and spatial scales. Repeat images have been widely used to measure long-term channel change, but these measurements are only significant if the magnitude of change exceeds the uncertainty. Existing methods for characterizing uncertainty have two important limitations. First, while the use of a spatially variable image co-registration error avoids the assumption that errors are spatially uniform, this type of error, as originally formulated, can only be applied to linear channel adjustments, which provide less information on channel change than polygons of erosion and deposition. Second, previous methods use a level-of-detection (LoD) threshold to remove non-significant measurements, which is problematic because real changes that occurred but were smaller than the LoD threshold would be removed. In this study, we present a new method of quantifying uncertainty associated with channel change based on probabilistic, spatially varying estimates of co-registration error and digitization uncertainty that obviates a LoD threshold. The spatially distributed probabilistic (SDP) method can be applied to both linear channel adjustments and polygons of erosion and deposition, making this the first uncertainty method generalizable to all metrics of channel change. Using a case study from the Yampa River, Colorado, we show that the SDP method reduced the magnitude of uncertainty and enabled us to detect smaller channel changes as significant. Additionally, the distributional information provided by the SDP method allowed us to report the magnitude of channel change with an appropriate level of confidence in cases where a simple LoD approach yielded an indeterminate result. © 2020 John Wiley & Sons, Ltd.     

Cryptosporidium and Giardia in Natural,Drinking, and Recreational Water of Northwestern Greece

An investigation about distribution of Giardia cysts and Cryptosporidium oocysts in natural, drinking, and recreational water in Northwestern Greece was performed. Five rivers (Aoos, Arachthos, Kalamas, Louros, and Voidomatis) and one lake (Pamvotis Ioannina Lake) in Northwestern Greece were investigated during a 10‐month period. Drinking and recreational water (swimming pools) from the area were also examined. Samples were collected from prefixed sampling stations and processed following a modification of standard methods for the microbiological examination of water, as suggested by the APHA/AWWA/WEF. Both Giardia cysts and Cryptosporidium oocysts were isolated from Pamvotis Ioannina Lake (15 positive/27 examined samples). Significantly lower numbers of Cryptosporidium oocysts were detected in Arachthos River (1/5), Voidomatis River (1/5), drinking water (1/7), and pool water samples (1/9). No Giardia cysts were detected, neither in river water, nor in drinking, and pool water samples. The results clearly show that, with the exception of Pamvotis Ioannina Lake, where contamination of high level was observed, natural water sources of the investigated area have low pollution, resulting in low contamination with parasites.     

Petrogenesis of main group pallasite meteorites based on relationships among texture,mineralogy, and geochemistry

Main group pallasite meteorites are samples of a single early magmatic planetesimal, dominated by metal and olivine but containing accessory chromite, sulfide, phosphide, phosphates, and rare phosphoran olivine. They represent mixtures of core and mantle materials, but the environment of formation is poorly understood, with a quiescent core–mantle boundary, violent core–mantle mixture, or surface mixture all recently suggested. Here, we review main group pallasite data sets and petrologic characteristics, and present new observations on the low‐MnO pallasite Brahin that contains abundant fragmental olivine, but also rounded and angular olivine and potential evidence of sulfide–phosphide liquid immiscibility. A reassessment of the literature shows that low‐MnO and high‐FeO subgroups preferentially host rounded olivine and low‐temperature P₂O₅‐rich phases such as the Mg‐phosphate farringtonite and phosphoran olivine. These phases form after metal and silicate reservoirs back‐react during decreasing temperature after initial separation, resulting in oxidation of phosphorus and chromium. Farringtonite and phosphoran olivine have not been found in the common subgroup PMG, which are mechanical mixtures of olivine, chromite with moderate Al₂O₃ contents, primitive solid metal, and evolved liquid metal. Lower concentrations of Mn in olivine of the low‐MnO PMG subgroup, and high concentrations of Mn in low‐Al₂O₃ chromites, trace the development and escape of sulfide‐rich melt in pallasites and the partially chalcophile behavior for Mn in this environment. Pallasites with rounded olivine indicate that the core–mantle boundary of their planetesimal may not be a simple interface but rather a volume in which interactions between metal, silicate, and other components occur.     

Continental rifting as a function of lithosphere mantle strength

The role of the uppermost mantle strength in the pattern of lithosphere rifting is investigated using a thermo-mechanical finite-element code. In the lithosphere, the mantle/crust strength ratio (S_M/S_C) that decreases with increasing Moho temperature T_M allows two strength regimes to be defined: mantle dominated (S_M > S_C) and crust dominated (S_M < S_C). The transition between the two regimes corresponds to the disappearance of a high strength uppermost mantle for T_M > 700 °C. 2D numerical simulations for different values of S_M/S_C show how the uppermost mantle strength controls the style of continental rifting. A high strength mantle leads to strain localisation at lithosphere scale, with two main patterns of narrow rifting: “coupled crust–mantle” at the lowest T_M values and “deep crustal décollement” for increasing T_M values, typical of some continental rifts and non-volcanic passive margins. The absence of a high strength mantle leads to distributed deformations and wide rifting in the upper crust. These numerical results are compared and discussed in relation with series of classical rift examples.     

Helgoland Roads,North Sea: 45 Years of Change

The Helgoland Roads time series is one of the richest temporal marine data sets available. Running since 1962, it documents changes for phytoplankton, salinity, Secchi disc depths and macronutrients. Uniquely, the data have been carefully quality controlled and linked to relevant meta-data, and the pelagic time series is further augmented by zooplankton, intertidal macroalgae, macro-zoobenthos and bacterioplankton data. Data analyses have shown changes in hydrography and biota around Helgoland. In the late 1970s, water inflows from the south-west to the German Bight increased with a corresponding increase in flushing rates. Salinity and annual mean temperature have also increased since 1962 and the latter by an average of 1.67°C. This has influenced seasonal phytoplankton growth causing significant shifts in diatom densities and the numbers of large diatoms (e. g. Coscinodiscus wailesii). Changes in zooplankton diversity have included the appearance of the ctenophore Mnemiopsis leidyi. The macroalgal community also showed an increase in green algal and a decrease in brown algal species after 1959. Over 30 benthic macrofaunal species have been newly recorded at Helgoland over the last 20 years, with a distinct shift towards southern species. These detailed data provide the basis for long-term analyses of changes on many trophic levels at Helgoland Roads.     

Deep groundwater mediates streamflow response to climate warming in the Oregon Cascades

Recent studies predict that projected climate change will lead to significant reductions in summer streamflow in the mountainous regions of the Western US. Hydrologic modeling directed at quantifying these potential changes has focused on the magnitude and timing of spring snowmelt as the key control on the spatial–temporal pattern of summer streamflow. We illustrate how spatial differences in groundwater dynamics can also play a significant role in determining streamflow responses to warming. We examine two contrasting watersheds, one located in the Western Cascades and the other in the High Cascades mountains of Oregon. We use both empirical analysis of streamflow data and physically based, spatially distributed modeling to disentangle the relative importance of multiple and interacting controls. In particular, we explore the extent to which differences in snow accumulation and melt and drainage characteristics (deep ground water vs. shallow subsurface) mediate the effect of climate change. Results show that within the Cascade Range, local variations in bedrock geology and concomitant differences in volume and seasonal fluxes of subsurface water will likely result in significant spatial variability in responses to climate forcing. Specifically, watersheds dominated by High Cascade geology will show greater absolute reductions in summer streamflow with predicted temperature increases.     

Heavy-ion irradiation on crystallographically oriented cordierite and the conversion of molecular CO2 to CO: a Raman spectroscopic study

Crystallographically oriented sections of natural gemstone quality cordierite single-crystals have been irradiated with swift heavy ions of GeV energy and various fluences. Irradiation effects on the crystal lattice were investigated by means of Raman spectroscopy. Raman line scans along the trajectory of the ions reveal a close correlation of beam parameters (such as fluence and energy loss dE/dx along the ion path) to strain due to associated changes in lattice dimensions and defect concentration. The luminescence background also scales with the ion fluence and suggests the formation of point defects, which could also account for the macroscopically observable colouration of the irradiated samples. In addition, changes in the amount and nature of volatile species inside the structural channels are observed. They also scale with dE/dx and confirm the previously postulated irradiation-induced conversion of CO₂ to CO. Irradiations along the crystallographic a-, b- and c-axis reveal no significant anisotropy effect with respect to lattice alterations. The polarisation characteristics of the Raman-active modes confirm the preferred molecular alignment of CO and CO₂ along the a-axis direction.     

Using the Hazus-MH flood model to evaluate community relocation as a flood mitigation response to terminal lake flooding: The case of Minnewaukan, North Dakota, USA

Devils Lake, a terminal lake in eastern North Dakota, has risen nearly 9.0 m since 1993, resulting in over $1 Billion in direct federal payments for disaster mitigation. More than 500 homes and 700 total structures have either been relocated or destroyed by the rising lake. The City of Minnewaukan, once nearly 13.0 km from the lake shoreline, is now facing the possibility of partial or complete relocation.We use the Hazus-MH MR4 Flood Model to examine potential flood damages in Minnewaukan associated with potential future lake levels ranging from 442.57 to 445.01 m at fixed water surface elevation (WSE) increments. We use three data sets to conduct a level 2 analysis in which user-supplied data allows for a site-specific analysis of flood damages. These include: 1) structure elevation surveyed by the U.S. Army Corps of Engineers, b) the 2010 Real Property Assessment Book for the City of Minnewaukan, and c) more than 200 individual property cards. Flood depth grids were provided by the Federal Emergency Management Agency in the form of bare-earth digital elevation models derived from LiDAR point clouds. Results include a series of graduated circle flood maps showing the location and assessed value of inundated buildings, and flood damage profiles showing the cumulative number of buildings inundated and their assessed value over a range of WSE increments.We show that the functionality of Hazus-MH can be extended to examine lakeshore flood hazards, and that it provides an important geovisualization tool in evaluating relocation as a flood mitigation alternative.     

Dust devil speeds, directions of motion and general characteristics observed by the Mars Express High Resolution Stereo Camera

A total of 205 dust devils were detected in 23 High Resolution Stereo Camera (HRSC) images taken between January 2004 and July 2006 with the ESA Mars Express orbiter, in which average dust devil heights were ∼660 m and average diameters were ∼230 m. For the first time, dust devil velocities were directly measured from orbit, and range from 1 to 59 m/s. The observed dust devil directions of motion are consistent with data derived from a General Circulation Model (GCM). In some respects HRSC dust devil properties agree favorably with data from the NASA Mars Exploration Rover Spirit dust devil analyses. The spatial distribution of the active dust devils detected by HRSC supports the conjecture that the ascending branch of the Hadley circulation is responsible for the increase in dust devil activity, especially observed during southern summer between 50° and 60° S latitude. Combining the dust-lifting rate of 19 kg/km²/sol derived from the Spirit observations with the fewer in number but larger in size dust devils from various other locations observed by HRSC, we suggest that dust devils make a significant contribution to the dust entrainment into the atmosphere and to the martian dust cycle.     

Proposed methods for potential evapotranspiration calculation of the Red River basin (North Vietnam)

Potential evapotranspiration (ETP) is an important part of a climatic water balance and a crucial variable in many kinds of models in computing actual evapotranspiration. The objective of this study was to find a reasonable approach of ETP calculation for a height‐differentiated landscape in subtropical climate. From the pool of diverse approaches, six common methods [Hamon, Priestley–Taylor, Thornthwaite, Blaney–Criddle, Turc and Food and Agricultural Organization Irrigation and Drainage Paper No. 56 (FAO‐56)] were selected. With the meteorological data for long‐term period (1964–2008), the calculation of ETP values was performed for 12 different meteorological stations in the Red River basin. Among the applied ETP calculation methods, the Turc and the FAO‐56 methods agreed well at most stations and represent best the expectations for the ETP values of the Thao and Da subbasins. The findings of our investigations indicate that in highly structured (land use and elevation) regions, not all methods provide satisfying results. Copyright © 2011 John Wiley & Sons, Ltd.