Fluvial Processes Research Articles

Geomorphologic Evolution and Morphometric Analysis of the Upper Basin (Güzelsu) of the Engil River (Van)

The study area is located in the Eastern Anatolian Plateau found in the Alpine-Himalayan fold mountain belt. The Engil River Upper Basin (Güzelsu) is within the Lake Van Closed Basin, the largest soda lake in this belt in terms of volume and area. This study aims to investigate the geomorphologic evolution of the Güzelsu Basin and support this development with morphometric analysis. With this aim, a Digital Elevation Model (DEM) was created with the aim of quantifying and evaluating field observations and findings, 22 subdrainage areas located in the basin was determined by the DEM. The indices of Hypsometric integral, Hypsometric curve, Basin shape, Elongation ratio, Drainage basin asymmetry, Mountain front sinuosity ratio, Valley width-height ratio were applied to these drainage areas which were formed depending on internal and external processes. When the geomorphological and sedimentological findings in the field studies were evaluated with the applied index results, it was revealed that the basin geomorphology was formed under the influence of tectonism, climate and fluvial processes.

Debris‐Flood Hazard Assessments in Steep Streams

AbstractDebris floods most commonly occur in steep mountain channels and on their alluvial fans but can also occur on small gravel bed rivers with watershed areas up to several hundred square kilometers. This became obvious during July 2021 and November 2021 debris floods in northwestern Germany and southwestern British Columbia, Canada. We subdivide debris floods into three categories: those triggered by a supra‐critical bed shear stress ratio, form by dilution from debris flows, and resulting from outbreak floods. This trichotomy challenges traditional hazard assessments; debris floods classify as a fluvial process, yet their destructive mechanics are difficult to characterize. Key hazards interact spatially and temporally in debris floods: inundation, scour, sediment transport and deposition and bank erosion. We describe approaches to quantify hazards by systematically accounting for these processes and introduce a novel approach for hazard quantification and mapping in which flow velocity, depth, and presumed fluid density are combined with the annual event frequency for all event scenarios. The derivative “composite hazard maps” are equally valid for debris floods and debris flows. Isolines of bank erosion based on a probabilistic analysis of a physically based model are added to capture the potential of debris floods to abruptly widen their channels. Substantial challenges remain, specifically in the reliable prediction of sediment transport and progressive bank erosion. Our intention is to homogenize debris‐flood hazard assessments and especially mapping methodologies. This could allow for systematic integration with landuse policies assuring consistency among approaches executed by practitioners acting in this field.

Geomorphology of the Aran Valley (Upper Garonne Basin, Central Pyrenees)

ABSTRACT Geomorphological mapping in mountain regions is key for a better understanding of past and present environmental dynamics. Here, we present a 1:25000 scale geomorphological map covering 553 km2 of the Aran Valley, Upper Garonne Basin (Central Pyrenees). The map identifies 44 different geomorphological units classified under glacial, periglacial, nival, karst, slope, alluvial, and fluvial categories. The area includes geomorphic evidence of past Quaternary glaciations reconstructed based on the distribution of moraines from the valley floor to the highest cirques. Following deglaciation of the valley, the landscape was mainly reshaped by periglacial, slope, alluvial and fluvial processes. In addition to paleoenvironmental reconstruction, the map can also be used to promote geoheritage and geoconservation, as well as for planning. As such, it is of relevance for areas exposed to natural hazards, since present-day slope failures and debris flows frequently impact the villages and infrastructures across the valley floor.

Fluvial processes and landforms

Abstract The period 1965–2000 saw a sustained increase in research and publications on fluvial processes and landforms. The trend towards generalization and/or mechanistic understanding, rather than site-specific history, continued. Research was multidisciplinary, with important contributions from hydraulic engineers, geologists and physical geographers and from experimental and theoretical approaches as well as geomorphological and sedimentological fieldwork. Rapidly increasing computer power underpinned new measurement methods, and greatly increased the scope of data analysis and numerical modelling. There were major advances in understanding the interaction of river process and form at reach scale, with growing recognition of differences between sand-bed and coarse-bed rivers. Field studies outside Europe and North America led to greater awareness of the diversity of river planforms and depositional landforms. Conceptual models of how rivers respond to natural or anthropogenic change in boundary conditions at different timescales were refined, taking advantage of studies of the response to land-use change, major floods and volcanic eruptions. The dating of sediments allowed greater appreciation of fluctuations in the incidence of extreme driving events over centuries and thousands of years. Towards the end of this period, research on bedrock rivers began to take off.

Quantitative reconstruction of the vegetation of the Qinhuangdao area, western coast of Bohai Sea, North China, during the Little Ice Age

It is widely recognized that the climate of the Little Ice Age (LIA) was generally cold. However, there are differences in the climate response of the vegetation in different regions during the LIA, and high-resolution quantitative research is lacking. Here, we present a high-resolution pollen analysis and the Landscape Reconstruction Algorithm (LRA) based on relative pollen productivity, combined with AMS 14C dating, to quantitatively reconstruct the vegetation response to climate and sea level change on the western coast of Bohai Sea. The main findings are as follows: (1) The coverage of the main plant taxa reconstructed using estimates of relative pollen productivity was closer to the actual vegetation conditions than that based on pollen percentages. (2) Since ∼1250 A.D., the study area was occupied by temperate deciduous broadleaved forest, dominated by Quercus, with a smaller proportion of Pinus forest. The regional vegetation types did not change significantly, but the forest cover decreased gradually from ∼60% in the Middle Warm Period (MWP, 1250–1310 A.D.) to ∼40% in the LIA (1310–1610 A.D.), due to the combined influences of climate and human activities. (3) The composition of herbaceous plants changed substantially during the LIA. In the early LIA (1310–1450 A.D.), the climate became cold and dry and the sea level began to fall, resulting in a substantial increase in the proportion of Poaceae (∼10%). In the middle of the LIA (1450–1610 A.D.), the climate became colder and drier, the sea level fell further, and the lagoon shrank. In response, there was an increase in drought and salt-tolerant Chenopodiaceae (∼10%) and Artemisia (∼5%), a substantial increase in Selaginella sinensis supplied by fluvial processes.

Two-dimensional modeling of channel evolution under the influence of large-scale river regulation works

In the middle and lower reaches of alluvial rivers, various kinds of river regulation projects affecting natural channel evolution often are distributed due to the requirements of flood control, navigation, and channel stability. However, the influence of large-scale river regulation works on fluvial processes is not fully known. Therefore, a two-dimensional (2D) morphodynamic model has been improved to address this problem. The new detailed procedure is presented in this paper: (i) First, each node in the study domain was labeled using a specified point code to distinguish the zones with or without regulation works; and (ii) second, a 2D model was improved to consider the effect of river regulation works. In the refined model, the modules of sediment transport and bed deformation were treated separately in different zones. In the unprotected zones, both bed deposition and erosion were likely to occur. In the protected zones, bed erosion could not occur owing to the protection provided by the river regulation works, unless there was a deposition layer newly formed over the previous simulation periods. The observed data of the years 2004 and 2008 were used to calibrate and verify the improved 2D morphodynamic model which was applied in a 68-km-long reach of the Middle Yangtze River. Satisfactory results were obtained indicating that the improved model can better simulate the process of sediment transport and the morphology adjustment in three central bars in the study reach.

How Fluvial Deposits Distort Aquifer Recharge Estimated From Groundwater Age: Insights From a Landscape Evolution Model

AbstractSustainable management of groundwater relies on robust estimates of aquifer fluxes. As such, recharge can be estimated from groundwater age using analytical models assuming a homogeneous aquifer. We propose to assess how this assumption affects recharge estimates in fluvial deposits. First, we use CHILD, a landscape evolution model, to generate plausible deposits after tens of thousands of years of river evolution. Then, we use the fractional packing model to compute porosity and permeability of unconsolidated sediments assuming a mixture of a coarse and a fine fraction. Finally, we use PFLOTRAN to simulate groundwater flow and mean age over two thousand years of spatially uniform recharge. This reproduces the boundary conditions underlying Vogel's analytical model to estimate recharge rates. Our results are based on 20,000 realizations from varying inputs: grain sizes, aggradation rate of the river, porosity, recharge, etc. For most models, the mean estimate of the recharge rate remains below an absolute error of 25%. But fluvial heterogeneities can lead to local errors ranging from close to zero to several thousand percent, which means that estimates may vary drastically depending on sampling locations. A sensitivity analysis using the δ‐importance measure and CUSUNORO curves exposes how fluvial processes influence the range and distribution of the error. For instance, a high bank erodibility and small coarse grain size under low aggradation rates favor the reworking of deposits, which increases heterogeneity and leads to high errors. This work paves the way for a more reliable estimation of recharge by considering the sedimentary context.

Dataset of "Using a dense seismic array to study fluvial processes in a braided river reach under flood conditions"

Dataset of "Using a dense seismic array to study fluvial processes in a braided river reach under flood conditions"

The geomorphic origin of large wetlands in Africa’s elevated drylands: a Geographic Information System and Earth Observation approach

ABSTRACT The topographic, climatic and tectonic conditions of the sub-continent present opportunities to better understand the role that geomorphological processes play in determining the origin of large wetlands. Yet, there is limited information on the geomorphic origin of large wetlands in southern and eastern Africa due to wetland inaccessibility and limited wetland geomorphological studies that have been conducted in these regions. The current study aims to provide an understanding of the geomorphic origin of large wetlands in Africa’s elevated drylands. Satellite images were used to identify geomorphic features, while digital elevation models were used for topographic analysis, and geological maps provided tectonic and lithological information. Abductive reasoning was used to infer geomorphic features to processes that could have led to their formation while drawing inference from existing knowledge or relevant literature. The study demonstrated different processes that contribute to wetland formation, structure, and evolution. In some instances, tectonic processes may be primarily responsible for the formation of basins that hosts wetlands such as Wembere and Bahi wetlands in Tanzania. In other cases, wetlands such as the Lufira and Barotse wetlands in the Democratic Republic of Congo and Zambia, respectively, may be structured primarily by fluvial processes.

Geomorphological modeling of tidal inlets for sustainable deltaic lagoon management: A case study from the Po River delta, Italy

River deltas and enclosed lagoons represent a zone where fluvial and littoral processes interact through the redistribution, erosion, and deposition of sediment, which have a large impact on coastal management and engineering. The focus of the study is to understand the correct balance between strategies that maintain the navigational efficiency of tidal inlets and those that respect the ecological and economical functions of coastal lagoons. We applied an integrated modeling system that links multiple hydrodynamic and morphodynamic models to understand how coastal processes and associated sediment transport influences the functioning of the southern inlet of the Barbamarco Lagoon in the Po River Delta, Italy. Moreover, our study provides engineering solutions to improve the inlet functioning efficiency and a proposal for a monitoring plan. Our results highlight the importance of the seasonal effects of wave climate on the littoral sediment transport. Model outcomes show that the dredging volume is approximately 15,000 cubic meter/year for the southern inlet, which may vary with wave climate. However, creating a wider seaward tidal channel will reduce dredging activities over a longer interval than would sediment removal. A deeper and wider channel will deflect the along shore current seaward and cause sediment to bypass the inlet. Therefore, the sediment will reach the erosional side of the inlet and enhance the redistribution of the sediment, which may reduce over wash during storms and high-water levels. Our results illustrate the ephemeral equilibrium of tidal inlets and coastal lagoons in deltaic systems impacted by large riverine sediment delivery. Shore management scenarios and decisions rely on hydro-morphodynamic numerical models that predict best practices for coastal sustainability.

Statewide USGS 3DEP Lidar Topographic Differencing Applied to Indiana, USA

Differencing multi-temporal topographic data (radar, lidar, or photogrammetrically derived point clouds or digital elevation models—DEMs) measures landscape change, with broad applications for scientific research, hazard management, industry, and urban planning. The United States Geological Survey’s 3D Elevation Program (3DEP) is an ambitious effort to collect light detection and ranging (lidar) topography over the United States’ lower 48 and Interferometric Synthetic Aperture Radar (IfSAR) in Alaska by 2023. The datasets collected through this program present an important opportunity to characterize topography and topographic change at regional and national scales. We present Indiana statewide topographic differencing results produced from the 2011–2013 and 2016–2020 lidar collections. We discuss the insights, challenges, and lessons learned from conducting large-scale differencing. Challenges include: (1) designing and implementing an automated differencing workflow over 94,000 km2 of high-resolution topography data, (2) ensuring sufficient computing resources, and (3) managing the analysis and visualization of the multiple terabytes of data. We highlight observations including infrastructure development, vegetation growth, and landscape change driven by agricultural practices, fluvial processes, and natural resource extraction. With 3DEP and the U.S. Interagency Elevation Inventory data, at least 37% of the Contiguous 48 U.S. states are already covered by repeat, openly available, high-resolution topography datasets, making topographic differencing possible.

Assessment and prediction of shoreline change using multi-temporal satellite data and geostatistics: A case study on the eastern coast of India

Abstract Climate change and rising sea level is transforming global coastlines as corroborated by significant changes in the position of shoreline witnessed through coastal erosion or accretion. Andhra Pradesh has the second longest (972 km) coastline in India. The present study analyzed shoreline change and its future prediction by employing satellite-derived data and geographic information system. End point rate (EPR) and linear regression rate (LRR) statistical tools in the Digital Shoreline Analysis System (DSAS) were used to estimate historical shoreline change rate between 1973 and 2015. Erosion and accretion of the coastline were delineated from Landsat satellite images for 1973, 1980, 1990, 2000, 2010, and 2015; subsequently, shoreline is predicted for short-term (2025) and long-term (2050) periods. The study showcased that the river mouths of Krishna and Godavari experienced higher rate of change in shoreline position influenced by the deltaic environment and fluvial processes. LRR model prediction depicts the average rate of shoreline change during 2015–2025 will be −4.64 m, while between 2015 and 2050 it will increase to −16.25 m. The study observed that the error between predicted and actual shoreline is higher in the river mouth and deltaic plains. Predicted shoreline position will provide baseline information for adaptation strategies and policy framework for coastal management.

Research into Cryolithozone Spatial Pattern Changes Based on the Mathematical Morphology of Landscapes

Lacustrine thermokarst is receiving great interest as a landscape-forming process. Despite this, research dealing with the quantitative analysis of the changes in the morphological patterns of thermokarst plains under ongoing climate change is lacking. This study aims to analyze changes in the morphological patterns of cryolithozone landscapes based on models provided by the mathematical morphology of landscapes. Our research involves eight key sites within lacustrine thermokarst plains and nine key sites within thermokarst plains with fluvial erosion. These sites differ in geomorphological, geocryological, and physiographical terms, and are situated in different regions such as Yamal, Taimyr, Kolyma lowland, river Lena delta, Baffin’s Land, and Alaska. Archival Corona images (date 1) and high-resolution satellite imagery from June to August 2008–2014 (date 2) were used to obtain the model’s morphometric data. According to quantitative analysis of the models, the morphological pattern of the lacustrine thermokarst plains did not undergo significant changes during the observation period, while 20% of the key sites within the thermokarst plains with fluvial erosion underwent essential changes in lake area distributions. This difference may come from the higher reactivity of the fluvial erosion process on climate change than that of the thermokarst.

Controls on composition and diagenesis of wave- and river-dominated deltas: impacts on reservoir properties. An example from the La Anita Formation (Argentina)

Wave-, tidal-, and fluvial-dominated deltas are important hydrocarbon reservoirs worldwide, and it is well known that depositional facies types, detrital composition and diagenetic products are key aspects when evaluating potential reservoir properties. Moreover, detrital composition and diagenetic products are controlled by external forces such as tectonism, climate, and depositional conditions.The Upper Cretaceous La Anita Formation (Austral-Magallanes Basin, Argentina) is a deltaic succession that shows a clear vertical variation in the relative role of wave, tidal and fluvial processes. The formation was accumulated during the foreland stage of the basin under relatively warm climate conditions. A detailed compositional and diagenetic analysis for these deposits is provided to evaluate the role of the controlling factors on the detrital and authigenic composition, and the impact on reservoir properties.Samples were analyzed by conventional petrography, X-ray diffraction and scanning electron microscopy to obtain a full spectrum of its detrital, authigenic and diagenetic composition. The analyzed sandstones were classified as lithic arenites which come from the fold-thrust belt region and from the magmatic arc located toward the westward. The clay mineral composition is characterized by variable proportions of illite, smectite, kaolinite and mixed-layer illite-smectite with the sporadic presence of chlorite. Stratigraphic variations in the abundance of authigenic kaolinite and smectite indicate a change in the climatic conditions during the depositions of the unit evolving from tropical to more temperate conditions. Diagenetic processes affecting the porosity are considered as controlled mainly by the lithological nature of the deposits and depositional facies type. Sandstone porosity is mainly primary in origin, moderate to good in abundance and show micropore to mesopore as the main pore-sizes.This work enhances that the diagenetic products are heavily controlled by the dominant depositional process. The presence of diagenetic products as quartz overgrowth and calcite and hematite cement reduces pore spaces and affects the reservoir properties. The development of these types of cement is conditioned by the relative dominance of wave and river processes. Under wave-dominated conditions, quartz tends to develop thick overgrowths. Conversely, under river-dominated conditions quartz overgrowths are thinner and calcite and hematite cementation patches are developed.

The Need for Protecting, Promoting, and Managing a Quaternary Geoheritage Site: Bahluieț Valley at Costești Village (Moldavian Plateau, North-Eastern Romania)

The Bahluieț Valley at Costești village geosite has recently been studied and proposed as a geoheritage site. Previous investigations of the study area were focused on the Costești-Cier archaeological site, which is currently integrated into the National Archaeological Repertoire. In this archaeological site, different levels of populations have been studied (Eneolithic Cucuteni A, Cucuteni AB, and Horodiștea-Erbiceni Culture populations) as well as an earth wall from La Tene (8th‒10th/eleventh century BC) and a 15th‒seventeenth century AD necropolis. In the area of the present-day Costești village, Bahluieț River leaves the Suceava Plateau area (with altitudes of 350‒550 m a.s.l.) and enters the Jijia Hills (with altitudes of 50 to 200 m a.s.l.), flowing between Ulmiș Hill (306 m a.s.l., at north) and Ruginii Hill (326 m a.s.l., at the south). This valley, which is incised more than 100 m below the plateau level, suddenly becomes broader because of massive Late Pleistocene landslides that covered the former Bahluieț river floodplain and are now fossilized by fluvial deposits. During the Holocene, river incision detached paleochannels and fluvial terraces, while the landslides reactivated through retrogressive mechanisms, creating a complex landslide. A cut-off meander island hosts the Costești-Cier archaeological site, which is currently being actively eroded by the river. In the riverbank of this island, a multi-layered stratigraphy can be seen, consisting of landslide and fluvial deposits, palaeosols, and archaeological remains. The layered deposits, the complex landslide, and the fluvial processes have the potential to become one of the most representative Quaternary sites of the Moldavian Plateau and Romania. By using geomorphosite assessment, geomorphological mapping, optically stimulated luminescence dating, and concepts of geoconservation, I show (i) the importance of the geosite due to the presence of the oldest dated fossil landslide in Romania and to the landslide-fluvial-archaeological relations and (ii) the need for protection at local, regional, and national levels considering the active processes that affect the site. I propose a geoconservation strategy for management and promotion of the geoheritage site.

Late Quaternary landform evolution and sedimentary successions in the Miaoli Tableland, northwestern Taiwan

Abstract. Elevated Quaternary sedimentary complexes in the western foreland of the central mountain ranges of Taiwan are called tablelands. Their mostly flat surfaces are deeply incised by fluvial processes. The landforms and the fluvial systems in the Miaoli Tableland are investigated by high-resolution terrain analyses based on different datasets. Sediments are described in 51 outcrops and characterized by grain size composition. The outcrops revealed complete or incomplete sequences of the general scheme from bottom to top: sandy tidal–coastal units overlain by gravel- and cobble-rich fluvial deposits always with a fine-grained silt-rich top cover layer influenced by aeolian deposits. All layers are unconsolidated sediments. Three subtypes of this sequence were identified, with respect to the occurrence of the fluvial deposits. The relation of tectonic and erosional processes including the rework of gravels is discussed. The results reveal a tableland surface much more disaggregated than previously mapped, suggesting that individual tableland segments represent remnants of an inferred palaeotopography. The tableland surfaces have been separated into Sedimentary Highlands (SH-I and SH-II) and Sedimentary Terraces (ST) by geometrical properties. The Alluvial and Coastal Plains (AL) represent broad valley bottoms (“box-shaped valleys”) in the dendritic drainage systems below 150 m and the coastal plains. The landforms and predominantly the sediment sequences are discussed in the context of the existing stratigraphical schemes of the Toukoshan Formation and the so far rarely used Lungkang Formation. The latter is recommended as the stratigraphical term for the refined subdivision of the uppermost part of late Quaternary sediments in the Miaoli Tableland.

Variations in geomorphological dynamics in the northern Khangai Mountains, Mongolia, since the Late Glacial period

In semi-arid central Mongolia, geomorphological dynamics and forest distribution are commonly regarded as a result of the climatic development over the Holocene. The aim of this study was to detect variations in geomorphological activity and related eolian, periglacial, colluvial and fluvial processes since the Late Glacial, triggered by climate changes and other factors such as regional lake-level changes, fire events, and human impact. For this purpose, we investigated sediment archives in various relief positions (slope, pediment, valley bottom, dune and lake shore) in a forest-steppe region at the northern edge of the Khangai Mountains. We used a combination of geomorphological mapping and sampling of sediments, soils, paleosols, and organic layers. The samples were subjected to sedimentological analysis, luminescence and radiocarbon dating.The ages obtained for the eolian sediments showed that intense eolian activity and periglacial processes occurred during the Last Glacial Period and mitigated after 11 ka. After the Younger Dryas, geomorphological processes decreased and intensified soil formation indicated a stabilization of the soil surface simultaneously when spreading of forests around 9.5 ka was previously shown in the Khangai Mountains. The early and mid-Holocene were characterized by minor geomorphological activity and low fire frequency, as documented by sparseness of charcoal fragments and paleosols in the sediments. Only between 8 ka and 7 ka, reactivation of eolian sand transport was recorded during a drier period.Widespread distribution of late Holocene colluvial, alluvial and eolian sediments containing abundant charcoal, and periglacial features point to a distinct turning point in the Holocene landscape development around 4.5 ka, when substantially enhanced geomorphological activity started. This enhanced geomorphic activity corresponds with a period previously shown to be more humid but also more unstable, and during which forests became more susceptible to severe fire events. After a forest fire, lack of vegetation cover favored intensive erosion. Enhanced geomorphological activity points to a trend towards desertification, which was increasingly aggravated by human impact, since pastoralism emerged latest in the early Bronze Age. Increased production of steppe biomass during humid periods led to growth of population and livestock. This growth in turn resulted in overgrazing in drier years. This mechanism probably amplified the aridity signals that were detected in proxies of various paleoenvironmental archives.

Wildfires and Monsoons: Cryptic Drivers for Highly Variable Provenance Signals within a Carboniferous Fluvial System

Sediment delivery and supply are explicitly controlled by variations in broad-scale processes such as climate, tectonics and eustasy. These in turn influence fluvial processes and hinterland evolution. A bespoke multi-proxy approach (integrating apatite and zircon U-Pb geochronology, trace elements in apatite, and Pb-in-K-feldspar provenance tools) coupled with outcrop investigation is used to constrain the temporal trends in sediment delivery to channel sandstones of the fluvio-estuarine mid-Viséan Mullaghmore Sandstone Formation, Ireland. Provenance data indicate unique detrital signatures for all sampled horizons, indicating the fluctuating nature of sediment supply to this medium-sized basin. Tectonism and/or abrupt relative sea-level fall likely caused fluvial rejuvenation, resulting in local basement sourcing of the initial fill. Older and more distal sources, such as the Nagssugtoqidian Belt of East Greenland, become more prominent in stratigraphically younger channel sandstones suggesting catchment expansion. Paleoproterozoic to Mesoproterozoic sources are most dominant, yet the detrital grain cargo varies in each channel sandstone. Proximal sources such as the Donegal Batholith and Dalradian Supergroup are variable and appear to switch on and off. These signal shifts are likely the result of channel migration and paleoclimatic fluctuation. A monsoonal climate and large-scale wildfire events (evidenced by fusain) likely contributed to modify plant cover, intensify erosion, and increase run-off and sediment delivery rates from specific areas of the hinterland.

Chemistry and mineralogy of Zr- and Ti-rich minerals sourced from Cox’s Bazar beach placer deposits, Bangladesh: Implication of resources processing and evaluation

Zircon is always found in association with Ti-rich minerals; therefore, it is produced mainly as a co-product in the production of ilmenite and rutile from placer mining operations. In Cox’s Bazar beach sands, they contain at 2.8, 12.1 and 2.7 wt% (average) respectively in the heavies. In order to scrutinize mineralogical and geochemical variability among Zr- and Ti- rich minerals, XRF, XRD, SEM and EPMA were implemented. Petrogenesis manifests the nature of impurities in mineral concentrates where they included through cationic substitution during alteration and metamictization, whereas their coating and pore filling occurred by hydraulic action in fluvial process. The impurities of oxides, silicates and phosphates gangue mineral phases degrade the quality of zircon concentrate (ZrO2 + HfO2 = 63.73 wt%) in achieving premium grade. Although the process of hot acid leaching (HAL) upgrades the quality enhancing ZrO2 + HfO2 (69.10 wt%) content, yet to be eliminated Fe and U to reach premium grade. Thermal annealing and calcining treatment is suggested to fully recover the zircon prior to industrial use. Similar to zircon, ilmenite and rutile they both contain trace levels of gangue mineral phases. The content of TiO2 and Ti/(Ti + Fe) (48.1 wt% and 0.5 respectively) indicates unaltered ilmenite. Therefore, upgrading the unaltered low grade ilmenite concentrate to chlorination feedstock, ilmenite smelting and the synthetic rutile routes are suggested. In addition, the TiO2 (83.84 wt%) content in the bulk rutile concentrate shows as much as the high grade ilmenite display due to contaminants. Mentioning, two of the major impurities such as tin and zirconium occurred as mineral grain cassiterite and zircon and as substitutions for titanium (Ti ⇌ Sn, Zr) in crystal lattice. The way of acid leaching can be instrumental not only for upgrading rutile but also for extracting Sn and Zr as byproduct of Ti metal/ TiO2 pigment.

Good vibrations: Big data impact bedload research

AbstractThe fact that bedload transport is an inherently time‐variant and location‐sensitive fluvial process was revealed by systematic sampling, nine decades ago. Subsequent stream‐wide measurements, that frequently incorporated lengthy collection periods, as well as the adoption of standardized sampling procedures, averaged out some temporal and spatial variability. However, continuous, highly resolved, long‐period records of transport activity generated by active and passive bedload monitoring on diverse rivers have recently brought this variability into sharp focus. A defining characteristic of these ‘big data’ is that there are many possible bedload transport rates for each discharge and a wide range of discharges associated with each transport rate. Crucially, this incoherent scatter, which is generated by the various factors that affect bedload transport, can no longer be viewed as ‘noise’ that can be averaged out. We demonstrate that, even for small datasets, different methods of reporting and analysing bedload transport records provide different perspectives on the bedload transport rate–flow relation. The inclusion/exclusion of zero values, present in all data that capture the intermittent nature of bedload transport, also affects the relation. To unlock the potential of big data and facilitate the development of bedload transport–flow relations from field measurements, it is essential to employ modes of analysis that are robust to outliers and do not assume that associations between the independent and dependent variables are the same at all levels.