Sedimentation patterns in the Selenga River delta under changing hydroclimatic conditions

The Selenga River delta (Russia) is a large (>600 km²) fluvially dominated fresh water system that transfers water and sediment from an undammed drainage basin into Lake Baikal, a United Nations Educational, Scientific, and Cultural Organization World Heritage Site. Through sedimentation processes, the delta and its wetlands provide important environmental services, such as storage of sediment‐bound pollutants (e.g., metals), thereby reducing their input to Lake Baikal. However, in the Selenga River delta and many other deltas of the world, there is a lack of knowledge regarding impacts of potential shifts in the flow regime (e.g., due to climate change and other anthropogenic impacts) on sedimentation processes, including sediment exchanges between deltaic channels and adjacent wetlands. This study uses field measurements of water velocities and sediment characteristics in the Selenga River delta, investigating conditions of moderate discharge, which have become more frequent over the past decades (at the expense of peak flows, Q > 1,350 m³ s^?1). The aims are to determine if the river system under moderate flow conditions is capable of supporting sediment export from the main distributary channels of the delta to the adjacent wetlands. The results show that most of the deposited sediment outside of the deltaic channels is characterized by a large proportion of silt and clay material (i.e., <63 μm). For example, floodplain lakes function as sinks of very fine sediment (e.g., 97% of sediment by weight < 63 μm). Additionally, bed material sediment is found to be transported outside of the channel margins during conditions of moderate and high water discharge conditions (Q ≥ 1,000 m³ s^?1). Submerged banks and marshlands located in the backwater zone of the delta accumulate sediment during such discharges, supporting wetland development. Thus, these regions likely sequester various metals bound to Selenga River sediment.     

Assessment of climate change and associated impact on selected sectors in Poland

The present paper offers a brief assessment of climate change and associated impact in Poland, based on selected results of the Polish–Norwegian CHASE-PL project. Impacts are examined in selected sectors, such as water resources, natural hazard risk reduction, environment, agriculture and health. Results of change detection in long time series of observed climate and climate impact variables in Poland are presented. Also, projections of climate variability and change are provided for time horizons of 2021–2050 and 2071–2100 for two emission scenarios, RCP4.5 and RCP8.5 in comparison with control period, 1971–2000. Based on climate projections, examination of future impacts on sectors is also carried out. Selected uncertainty issues relevant to observations, understanding and projections are tackled as well.     

Identifying the flow pattern and natural recharge at a strategic groundwater resource in the Dornogobi Province,Mongolia

The strategic project of economic development in the Dornogobi Province in Mongolia is dependent on water supply. Thus a comprehensive hydrogeological characterization was focused on the Upper Cretaceous multi-aquifer system north of Sainshand city. A conceptual model was developed to discover the groundwater flow pattern essential to correct the setting of the numerical model of groundwater flow created using MODFLOW to assess the natural recharge of the aquifer. The conceptualization was based on geological and hydrogeological characterization. However, the evaluation of hydrochemistry proved to be the key factor revealing the principal feature of the groundwater flow pattern, which is the presence of preferential flow zones. These zones allow for intensive transfer of relatively fresh Na(Mg,Ca)?HCO₃-dominated groundwater into discharge areas, where it leaks into the Quaternary aquifer. The numerical model suggested an enormous natural recharge of 22 100 m³/d, originating in 64% of the preferential flow zones.     

Distributed Temperature Sensing to Measure Infiltration Rates Across a Groundwater Recharge Basin

Managed aquifer recharge is used to augment groundwater resources and provide resiliency to water supplies threatened by prolonged droughts. It is important that recharge facilities operate at their maximum efficiency to increase the volume of water stored for future use. In this study, we evaluate the use of distributed temperature sensing (DTS) technology as a tool to measure high-resolution infiltration rates at a large-scale recharge facility. Fiber optic cable was laid out inside a spreading basin in a spiral pattern, at two different depths. The cables measured the propagation of diurnal surface water temperature oscillations into the basin depth. The rate of heat propagation is proportional to the velocity of the water, making it possible to estimate the infiltration rate from the temperature measurements. Our results showed that the infiltration rate calculated from DTS, averaged over the entire basin, was within 5% of the infiltration rate calculated using a conventional metering method. The high-resolution data obtained from DTS, both spatially and temporally, revealed heterogeneous infiltration rates throughout the basin; furthermore, tracking the evolution of infiltration rates over time revealed regions with consistently high infiltration rates, regions with consistently low infiltration rates, and regions that evolved from high to low rates, which suggested clogging within that region. Water utilities can take advantage of the high-resolution information obtained from DTS to better manage recharge basins and make decisions about cleaning schedule, frequency, and extent, leading to improved basin management strategies, reduced O&M costs, and increased groundwater recharge.     

Experimental and computational synergy for modelling an advanced gas-cooled reactor core under seismic excitation

The advanced gas-cooled reactors (AGRs) are the backbone of the United Kingdom's nuclear generation fleet, producing approximately 17% of the country's electricity. Their safety cases are supported by thorough inspection and monitoring of their graphite cores and extensive theoretical, analytical, and experimental studies. This paper presents a unique, highly innovative and technically challenging earthquake engineering project that has provided vital evidence to underpin the seismic safety assessments of the AGRs. Two modelling approaches, one experimental (a multilayer array physical model), and one numerical (a SOLFEC nonsmooth contact dynamics computational model) have been developed to investigate the seismic behaviour of an aged graphite core. The synergetic relationship between the two approaches is a product of insightful collaborative learning between the University of Bristol and Atkins, with the experiments providing material parameters and validation data and the computer simulations feeding array design and test schedule recommendations to the physical model. The predictive capabilities of the physical and the numerical models are tested by direct comparison and the good agreement between the results has increased the confidence in both. The model's versatility allows a variety of core scenarios to be tested that can explore in detail the AGR core behaviour in seismic conditions.     

Factors Influencing Helophyte Distribution in Lakes (Eastern Poland)

Water Resources - The aim of the study was to show which morphometric traits of lakes influence the development of the rush zone of lakes and how buffer zone management influences analyzed features...     

Using geographically weighted regression to explore the spatially heterogeneous spread of bovine tuberculosis in England and Wales

An understanding of the factors that affect the spread of endemic bovine tuberculosis (bTB) is critical for the development of measures to stop and reverse this spread. Analyses of spatial data need to account for the inherent spatial heterogeneity within the data, or else spatial autocorrelation can lead to an overestimate of the significance of variables. This study used three methods of analysis—least-squares linear regression with a spatial autocorrelation term, geographically weighted regression (GWR) and boosted regression tree (BRT) analysis—to identify the factors that influence the spread of endemic bTB at a local level in England and Wales. The linear regression and GWR methods demonstrated the importance of accounting for spatial differences in risk factors for bTB, and showed some consistency in the identification of certain factors related to flooding, disease history and the presence of multiple genotypes of bTB. This is the first attempt to explore the factors associated with the spread of endemic bTB in England and Wales using GWR. This technique improves on least-squares linear regression approaches by identifying regional differences in the factors associated with bTB spread. However, interpretation of these complex regional differences is difficult and the approach does not lend itself to predictive models which are likely to be of more value to policy makers. Methods such as BRT may be more suited to such a task. Here we have demonstrated that GWR and BRT can produce comparable outputs.     

Complex kame belt morphology,stratigraphy and architecture

The development of glacier karst at the margins of melting ice sheets produces complex glaciofluvial sediment-landform assemblages that provide information on ice sheet downwasting processes. We present the first combined geomorphological, sedimentological and geophysical investigation of the Brampton Kame Belt, an important glaciofluvial depositional zone at the centre of the last British-Irish Ice Sheet. Ground-penetrating radar (GPR) data allow the broad scale internal architecture of ridges (eskers) and flat-topped hills (ice-walled lake plains) to be determined at four sites. In combination with sediment exposures, these provide information on lateral and vertical variations in accretion styles, depositional boundaries, and grain size changes. Building on existing work on the subject, we propose a refined model for the formation of ice-walled lake plains resulting from the evolution and collapse of major drainage axes into lakes as stable glacier karst develops during deglaciation. The internal structure of esker ridges demonstrates variations in sedimentation that can be linked to differences in ridge morphologies across the kame belt. This includes low energy flow conditions and multiple accretion phases identified within large S-N oriented esker ridges; and fluctuating water pressures, hyperconcentrated flows, and significant deformation within a fragmented SW–NE oriented esker ridge. In combination with updated geomorphological mapping, this work allows us to identify two main styles of drainage within the kame belt: (1) major drainage axes aligned broadly S-N that extend through the entire kame belt and collapsed into a chain of ice-walled lakes; and (2) a series of smaller, fragmented SW–NE aligned esker ridges that represent ice-marginal drainage as the ice sheet receded south-eastwards up the Vale of Eden. Our study demonstrates the importance of integrated geomorphological, sedimentological and geophysical investigations in order to understand complex and polyphase glaciofluvial sediment-landform assemblages. © 2019 John Wiley & Sons, Ltd. © 2019 John Wiley & Sons, Ltd.     

Improved Method for Estimating Reaction Rates During Push-Pull Tests

The breakthrough curve obtained from a single-well push-pull test can be adjusted to account for dilution of the injection fluid in the aquifer fluid. The dilution-adjusted breakthrough curve can be analyzed to estimate the reaction rate of a solute. The conventional dilution-adjusted method assumes that the ratios of the concentrations of the nonreactive and reactive solutes in the injection fluid vs. the aquifer fluid are equal. If this assumption is invalid, the conventional method will generate inaccurate breakthrough curves and may lead to erroneous conclusions regarding the reactivity of a solute. In this study, a new method that generates a dilution-adjusted breakthrough curve was theoretically developed to account for any possible combination of nonreactive and reactive solute concentrations in the injection and aquifer fluids. The newly developed method was applied to a field-based data set and was shown to generate more accurate dilution-adjusted breakthrough curves. The improved dilution-adjusted method presented here is simple, makes no assumptions regarding the concentrations of the nonreactive and reactive solutes in the injection and aquifer fluids, and easily allows for estimating reaction rates during push-pull tests.     

New‐Build Development and the Gentrification of Oklahoma City's Deep Deuce Neighborhood

New‐build development has become associated with the phase of gentrification that has taken shape since the mid‐1990s. This article examines the gentrification of Deep Deuce, a historically black neighborhood in Oklahoma City. An analysis of property sales identifies the major external agents involved and leads to a discussion of the area's racial turnover. Considering the relational aspects of place, specifically how the identity of Deep Deuce has been constructed in relation to the nearby area of Bricktown, provides new insights on the nature of changes affecting this neighborhood. Supplementing this with an examination of resistance to the gentrification of Deep Deuce shows how city neighborhoods can come to be defined by limited understandings of place, and how historic preservation efforts can generate symbolic capital and facilitate cultural appropriation. This article also contributes to the study of gentrification in smaller metropolitan areas.