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Ijen Geopark, also known as "Sunrise of Java," is situated on the eastern tip of Java. Twelve geosites of the geopark are located in Banyuwangi Regency, while the left are situated in Bondowoso Regency. This paper aims to inventory and conduct a geosites quantitative assessment in Ijen Geopark in Banyuwangi Regency. A four-step model, comprising scientific value, potential educational value, potential tourism value, and degradation risk, is utilized for the quantitative assessment of the geosites. Geological characteristics of the twelve geosites have been inventoried. Ijen Acidic Crater Lake is the most valuable geosite in scientific terms. The publication of international papers can enhance the scientific score, particularly for geosites with a final scientific score below 300. All geosites in Ijen Geopark are potential for both education and tourism purposes, as they have final scores higher than 300. The Intrusive Rock Pulau Merah, despite facing moderate challenges related to population density and uniqueness, has been shown to have the greatest potential for both educational and tourism purposes. The geosites within Ijen Geopark are relatively protected from deterioration, with a total deterioration risk score less than 250. The study supports the efforts of local and national governments in promoting economic development. [ABSTRACT FROM AUTHOR]

This paper uses a 30 m record of valley alluviation in the Lockyer Creek, a major tributary of the mid-Brisbane River in Southeast Queensland, to document the timing and nature of Quaternary fluvial response. A combination of radiocarbon and optically stimulated luminescence dating reveals a sequence of major cut and fill episodes. The earliest aggradation phase is represented by a basal gravel unit, dating to ~220 ka (marine isotope sub-stage 7d), and although little evidence supports higher fluvial discharges during MIS 5, a MIS 3 fluvial episode characterised by incision and aggradation dates to ~60 ka. A penultimate phase of incision to a depth of 30 m prior to ~14 ka saw the lower Lockyer occupy its current position within the valley floor. The Lockyer Creek shows evidence of only minor fluvial activity during MIS 2, suggesting a drier LGM climate. The appearance of alternating fine- and coarse-grained units at about 2 ka is notable and may represent higher-energy flood conditions associated with a strengthening of El Niño Southern Oscillation activity as observed in the flood of 2011. The aggradation rate for this Holocene floodplain unit is ~11 times higher than the long-term rate. [ABSTRACT FROM AUTHOR]

Zones of alluviation at tributary – trunk confluences can act as sediment storage/transfer switches. Evaluating the temporal variation in tributary – trunk connectivity is key to understanding the origin, dynamics and residence time of tributary alluvial fill sequences, and determining relative and interacting effects of different drivers of landscape development. This paper evaluates processes and timescales of tributary (Prins River) – trunk (Touws River) connectivity at a site in the Little Karoo, as context for discussing sediment dispersal dynamics and implications for interpreting the landscape response to environmental change. An alluvial terrace in the tributary valley preserves a chronology (optically stimulated luminescence) of tributary valley alluviation that is regionally synchronous with valley alluviation in the upper Huis River and floodplain alluviation in the lower Touws and Groot rivers. A climatic shift within the Little Karoo at ~1000 years BP from relative aridity to relative humidity (and higher-energy rain-bearing circulation types) may have initiated widespread re-working of alluvial fills and the breaching of geomorphological buffers. Alternatively, there may be an intrinsic limit to sediment preservation potential associated with a regional floodplain cycling time of one to two thousand years. Longer archives are needed to contextualize fluvial responses to climatic variability in the region. [ABSTRACT FROM AUTHOR]

Streams are defined by the presence of a streambed, which is a linear depression where water flows between discernible banks. The upstream boundary of a stream is called a channel head. Headwater streams, which are small streams at the top of a watershed, account for the majority of the total length of streams, yet their exact locations are still not well known. For years, many algorithms were used to produce hydrographic networks that represent headwater streams with varying degrees of accuracy. Although digital elevation models derived from LiDAR have significantly improved headwater stream detection, the performance of the algorithms with different geomorphic characteristics remains unclear. Here, we address this issue by testing different combinations of algorithms using classification trees. Homogeneous hydrological processes were identified through hydrological classification. The results showed that in shallow soil that mainly consists of till deposits, the algorithms that recreate the surface runoff process provide the best explanation for the presence of a streambed. In contrast, streambeds in thick soil with high infiltration rates were primarily explained by a small-scale incision algorithm. Furthermore, the use of an iterative process that recreates water diffusion made it possible to more accurately detect streambeds than other methods tested, regardless of the hydrological classification. The method developed in this paper shows the importance of considering hydrological processes when aiming to identify headwater streams. [ABSTRACT FROM AUTHOR]

Bottom currents are key processes that contribute to the shaping of submarine slopes, with the redistribution of sediments in contourite systems. Despite numerous recent studies on contourite systems, the complexity and diversity of these sedimentary systems are still not fully understood and often underestimated. Their understanding requires comprehensive works integrating all scales from seismic architecture to microfacies. This paper focuses on a contouritic ridge located between 2000 m and 2500 m water depth on the Mozambique margin. Bathymetry, seismic data and piston cores collected during the PAMELA‐MOZ3 cruise allow a multi‐scale study from large depositional geometries to sedimentary facies. At the seismic scale, the contouritic ridge shows three stages of evolution with: (i) initiation and development of the drift/moat system; (ii) an intermediate stage with successive incisions and aggradations; and (iii) moat infill and drift erosion during the Plio‐Quaternary. Plio‐Quaternary deposits are composed of hemipelagic, turbiditic and contouritic facies filling the moat. Coarse‐grained contouritic facies, dominated by planktonic foraminifera, are identified on the western flank of the ridge between the moat infill and the erosional area at the top of the ridge. They consist of condensed deposits, with sedimentation rate about 0.3 cm/ka, indicating a strong and stable bottom current that winnows away the fine‐grained component. This facies could be present more generally in an intermediate position between erosion and depositional areas in contourite systems. At present, the contourite system is located at the transition depth between North Atlantic Deep Water and Antarctic Intermediate Water. Trajectories of bottom currents are complex and interact with sporadic turbidity currents and anti‐clockwise eddies that participate in reshaping the sea floor morphology. Although Plio‐Quaternary depositional geometries indicate the end of drift/moat development, the moat filling and drift erosion are also related to bottom currents and constitute atypical contouritic sedimentation. [ABSTRACT FROM AUTHOR]

The numerical simulation of non-uniform sediment transport under tidal flow in estuaries is a complicated, yet important, issue in Zhejiang estuaries. In this paper, a depth-averaged two-dimensional (2D) mathematical model for non-uniform sediment transport in estuaries is established and applied in Zhejiang tidal estuaries based on several newly derived formulas by Zhlin Sun et al. The model is validated using data from several experiments, including an aggradation test and an erosion test. Good performance in the tests indicates that the present model can simulate aggradation and erosion processes of non-uniform sediment. The model is also verified by observational data from the Jiaojiang estuary, and calculations agree well with measurements. The model is thus adaptable to simulating flow and non-uniform sediment transport in tidal estuaries. [ABSTRACT FROM AUTHOR]

The Jizera River in Czechia is a typical mid‐sized Central European watercourse. Its floodplain shows a morphological contrast between the laterally stable low‐sinuous current channel and preserved palaeomeanders. The aim of this paper was to date and explain the obvious metamorphosis of the channel pattern from meandering to low‐sinuous. We analysed the morphology of the lower river reach using a digital terrain model (DTM) and historical maps from the 1840s. Furthermore, the floodplain architecture was described based on the DTM, geophysical imaging (ground penetrating radar, GPR), sediment lithology and anthropogenic contamination using geochemical proxies, and optically stimulated luminescence (OSL) dating. The geochemical proxies were processed using log‐ratio methods from the compositional data analysis toolbox. According to our results the Jizera River showed signs of systematic lateral floodplain reworking during the Late Holocene with only minor aggradation, although parts of the catchment are covered by easily erodible loess. Interestingly, vertical aggradation did not show a significant increase during the last millennium. In the main study area, this limited vertical aggradation resulted in the preservation of palaeomeander fragments and palaeochannel belts with 100–200 m mean width in the 300–600 m wide floodplain, which are recognisable in the topography and in subsurface GPR imaging. This channel meandering took place between around 4 and 1.2 ka, and the transition towards the laterally stable modern channel with low sinuosity occurred around 1.2 ka. This timing indicates a climatic rather than anthropogenic impact, which was rather weak around that time. One likely cause for this transition was the influx of material from ravines incised into the sandstone valley edges during past climatic extremes. Subsequently, the re‐establishment of a meandering pattern was possibly prevented by a combination of low fluvial activity and the construction of weirs that reduced stream power. [ABSTRACT FROM AUTHOR]

Detrital 10Be from continental river sands or submarine sediments has been extensively used to determine the average long-term denudation rates of terrestrial catchments, based on the assumption that the rate of cosmogenic nuclide production by the interaction of source rocks with cosmic radiation balances out the loss of these nuclides by surface denudation. However, the 10Be signal recorded in sediments may be affected at the source by the response time of mountainous catchments to high-frequency forcings. In addition, transient sediment storage in piedmonts, alluvial plains and lakes or near the coast may also induce a difference between the erosive signal and its record in the sedimentary sink. Consequently, a significant part of the signal recorded in shallow-water sediments can be lost, as deep marine sediments may simultaneously record a signal coming from newly eroded source rocks along with one coming from the destabilization of previously deposited sediments. In this paper, we use the landscape evolution model Badlands to simulate erosion, deposition and detrital 10Be transfer from a source-to-sink sedimentary system (the Var River catchment, southern French Alps) over the last 100 kyr. We first compare model-based denudation rates with the ones that would be extracted from the 10Be record of local continental sediments (equivalent to river sands) and from sediments deposited offshore over time in order to examine if this record provides an accurate estimate of continental denudation rates. Then, we examine which conditions (precipitation rate, flexure, ice cover) satisfy published measured river incision rates and 10Be concentration in submarine sediments. Our results, based on the Var catchment cosmic ray exposure dating and modelling indicate that, while river sands do accurately estimate the average denudation rate of continental catchments, this is much less the case for deep submarine sediments. We find that deep-sea sediments have a different and often much smoother 10Be signature than continental ones and record a significant time lag with respect to imposed precipitation rate changes, representing the geomorphological response of the margin. A model which allows us to fit both measured 10Be concentration in marine sediments and river incision rates on land involves an increase in precipitation rates from 0.3 to 0.7 m yr -1 after 20 ka, suggesting more intense precipitation starting at the end of the Last Glacial Maximum. [ABSTRACT FROM AUTHOR]

The aim of this paper is to present a detailed geomorphological map of the western piedmont of Cumbres Calchaquíes (Tucumán Province, NW Argentina) bounded by the Amaicha River to the south and the administrative border with Salta Province to the north. It contains information about geomorphological units, their relative ages, and morphogenetic processes. The main map shows the presence of seven aggradation stages separated by incision phases. The first three stages (St1, St2, and St3) were modeled on a thick accumulation located in the upper piedmont from the Late Pliocene and Early Pleistocene. Intermediate stages (St4 and St5) are alluvial fans and pediments with less thickness and gradient. They cover the Early Pleistocene (St4) and the Late Pleistocene-Middle Holocene (St5). Finally, stages St6 and St7 are from the Upper Holocene. [ABSTRACT FROM AUTHOR]

Investigation of new geoheritage sites, their conservation and promotion for tourism development have become a recent trend in the tourism sector. The Indian subcontinent exhibits a wide range of geological and geomorphological features, many with global significance. The Kachchh district of Gujarat is blessed with such geological and geomorphological elements, ranging in age from Mesozoic to Recent. This study describes some geologically rich sites and their potential to be ranked as geoheritage sites. To analyze the potential, we carried out four assessments: scientific value, educational value, touristic value, and the degradational risk. A total of 18 geodiversity sites have been considered for this assessment, all of them with unique significance. The authors appeal to the government of India for the conservation of these geodiversity sites through this paper, as we identify that all of them are at risk of degradation. We also provide some suggestions for the promotion of geotourism, some of which the government may adopt. [ABSTRACT FROM AUTHOR]

Ephemeral channels incise into the piedmonts (both alluvial fans and pediments) of the northeastern Sonoran Desert, USA. Located around metropolitan Phoenix, this tectonically quiescent region experienced only aggradation in endorheic structural basins throughout the Pliocene. A wave of aggradation then followed Salt and Gila river integration at the start of the Pleistocene. Aggradation of piedmont base levels continued throughout the rest of the Quaternary. This paper explores two hypotheses to explain piedmont incision despite rising base levels. The classic explanation is that incision is part of the evolution of desert mountain ranges as they decrease in size. A new alternative we propose here involves a lateral shift in base level from Pliocene endorheic basin playas to positions kilometers closer to range fronts in response to river integration. We present a thought exercise of modeling a pediment longitudinal profile as a 1D diffusive system, and we also analyze incision into alluvial fans of the Sierra Estrella range. While our 1D modeling results for pediments are consistent with both explanations for range-front incision, Sierra Estrella bajada incision is best explained by the sudden relocation of the base level to the toe of desert piedmonts. [ABSTRACT FROM AUTHOR]

Conglomerate reservoirs in alluvial fans commonly contain economic crude oil, but it is challenging to depict the distribution of conglomerate reservoirs or to summarise the sedimentary model in alluvial fans deposits owing to their complex lithofacies changes and variable hydrodynamic conditions. This paper focuses on the Poplar River alluvial fan in the northwest Junggar Basin, China, as a special case to analyse its sedimentary processes and to build a sedimentary model through detailed outcrop mapping and grainsize analysis. The Poplar River alluvial fan is a braided river-dominated fan with the characteristics of a large fan size (approximate 327.6 km2), gentle slope (∼<0.04–0.07°), coarse sediments (mainly cobbles or finer pebbles) and rare fine-mud sediments deposited from floods. In this alluvial fan, 15 lithofacies are identified that mainly formed in five hydrodynamic environments: (i) debris-flow deposits; (ii) high-flow traction current deposits; (iii) low-flow traction current deposits; (iv) still-water deposits; and (v) eolian deposits. Moreover, the sedimentary processes on the Poplar River alluvial fan can be divided into flood and interflood periods. During flood periods, sediment deposition plays a major role on the alluvial fan. From the proximal to distal parts, six lithofacies associations can be identified: feeder-channel and sheet-flow deposits in the proximal part, sheet flood and braided-stream deposits in the intermediate part, and channel deposits and wetland deposits in the distal fan areas. During the interflood periods, sediment reworking is the most important function, and three lithofacies associations are identified: main-channel deposits in the proximal fan, braided-trench deposits in the intermediate fan and wetland deposits in the distal area. The braided-stream deposits, braided-trench deposits and sheet-flood deposits have the best potential for high-quality aquifers or oil reservoirs based on their moderately well-sorted grains and high primary permeable intervals. Fifteen lithofacies and eight lithofacies associations are identified in the Poplar River braided river-dominated alluvial fan. The aggradation process of the studied alluvial fan can be divided into flood and interflood periods. The flood-period braided-fluvial deposits, interflood main-channel and braided-trench channel deposits are the facies with best reservoir potential. [ABSTRACT FROM AUTHOR]

Hydropower is one of the renewable energy sources. Hydropower plants generate electricity using the kinetic energy of flowing water. Although hydroelectric power plants are not as prominent as solar or wind farms, it should be noted that they generate the most significant amount of the power. They are also the most technically advanced projects. Power plants are built with different technical parameters of turbines, different sizes of dams or weirs and different ways of exploiting the energy of flowing water. A common feature, however, is the significant impact of hydroelectric power plants on the functioning of adjacent regions. The paper divides this impact into economic and local development, landscape, and ecological functions, emphasizing the interaction of these influences. The paper discusses the hydromorphological changes taking place in the immediate vicinity of the structure, as a consequence of channel development. The processes of aggradation and degradation of the channel are the answer to hydrodynamic equilibrium loss. These hydrodynamic processes are associated with the subsequent ecological response of the habitat. The most important of these include the dynamic equilibrium loss by the river and the subsequent morphological parameters striving to restore it according to Lane's relation, known as the most important principle in the fluvial morphology science. The impact of the hydropower plant on the fluvial environment results, first of all, from a significant environmental impact of the damming of the river itself. If the structure is correctly designed, maintained, and operated, it allows controlling the water conditions upstream and downstream with simultaneous energy production. Due to several geometric, hydraulic, and granulometric changes, and further, the resultant economic, landscape, and natural changes that significantly affect the operation of a region, these should be considered as early as the design stage and should be an integral part of any hydroelectric project. [ABSTRACT FROM AUTHOR]

Most studies on the geomorphological evolution of the Holocene from the Ebro depression (NE Spain) are focused on the period up to the Roman Epoch (218 BC–476 AD) while some references to medieval (476 AD–15th century) deposits are also occasionally dated. This paper focuses on the establishment of aggradation units on the valley bottoms and slopes of the Ebro depression after 1400 BP, their origin, comparison with other areas, and relationship with global paleoenvironmental changes. These units were produced after the incision phase that marked the end of the large Holocene accumulation (unit H1) around 1400 BP (at the end of the Late Roman Epoch). Morphosedimentary records enable us to establish three aggradation units during the last 1400 years: unit H2 (ca. 1400–650 cal BP); unit H3 – with two H3A subunits (ca. 650–500 cal BP) and H3B (ca. 500–320 cal BP); and the H4 unit (after 320 cal BP). These units are organized following five types of aggradation/incision arrangements with differing complexities. There are also connections among these units and two slope stages in the region. Finally, the genetic relationships between these units and global paleoenvironmental changes are shown (LALIA, MCA, and LIA) and related to anthropic activity. This contribution is the first detailed and systematic approach to the study of morphosedimentary units and sedimentary arrangements during the Recent Holocene in the Mediterranean area. [ABSTRACT FROM AUTHOR]

This paper describes changes in bed morpho‐dynamics and topography in the River Ehen, a regulated river in NW England (i.e., temperate climate) following a rehabilitation project that reconnected a formerly diverted headwater sub‐catchment back to its main‐stem. Sediment grain‐size distributions in the Ehen changed subtly and in rather complex ways following the reconnection. Changes were most evident in the riffle morphological unit, where gravel‐sized material accumulated in the first 2 years after the reconnection. All morphological units initially experienced an addition of fine sediment (size <8 mm) but by the end of the study the proportion of fine material in the bed matrix had returned to pre‐reconnection levels. Topographic changes were evident in some units, with net aggradation in the riffle and scour in the plane bed; there was no detectable change in the pool. Albeit limited, there was evidence of an increase in bed mobility, with field observations indicating that the new sediment is moving over the top of the largely static existing pavement, rather than interacting with it. Despite numerous uncertainties related mainly to the ephemeral nature of the tributary and, consequently, how much sediment it would deliver, evidence suggests that the main project objective is being met: there is a renewed supply of sediment now being delivered to the main‐stem Ehen at times and in quantities that are controlled by natural processes. Nevertheless, the river is still best considered to be in an adjustment phase, so assessment of its long term response to the reconnection requires continued monitoring. [ABSTRACT FROM AUTHOR]

This paper focuses on the analysis of geomorphic landform development, particularly between the Trans Himadri Fault and the Main Central Thrust including Berinag Thrust and other major NNE–SSW and NW–SE striking faults/thrusts in the Higher Central Kumaun Himalaya. Digital analysis of remote sensing data, field investigations including drainage analysis, and development of landforms have been carried out to understand the morphotectonic evolution and, thereby, the neotectonics in this region. A number of morphometric indices [(stream length‐gradient index (SL), steepness index (ks), Chi (χ)] were computed together with knick point analysis. Offsetting of the major river and tributaries was observed along a NNW–SSE direction. Other tectonic landforms, including truncated saddles and disturbed terrace patterns, show that the area is presently undergoing active deformation. The valley floor morphology in the vicinity of the major thrusts provides evidence for aggradation of recent fluvial activity. Developments of various neotectonic features, such as starth terraces, off‐streams, truncated saddles, disrupted terraces, and palaeolake deposits, are evidences for recent tectonic activities associated with the major thrusts/faults. Cut‐and‐fill terraces with thick alluvial cover, debris‐flow terraces, and alluvial fan terraces are significant aggradational landforms observed within the valley that provide signatures of past climatic records. Our study reveals that the fluvially modified debris‐flow terraces were formed between 5 and 20 ka. We infer that the major phase of valley‐fill happened between 5 and 12 ka, whereas the youngest phase of aggradation may have responded to the Holocene tectonic activity that took place around 5–6 ka. The study is significant to understand the recent geomorphic development and tectonic deformation in the study area and may be helpful for future infrastructural development in the region. [ABSTRACT FROM AUTHOR]

Sediment connectivity in fluvial networks results from the transfer of sediment between multiple sources and sinks. Connectivity scales differently between all sources and sinks as a function of distance, source grain size and sediment supply, network topology and topography, and hydrologic forcing. In this paper, we address the challenge of quantifying sediment connectivity and its controls at the network scale. We expand the concept of a single, catchment-scale sediment cascade toward representing sediment transport from each source as a suite of individual cascading processes. We implement this approach in the herein presented CAtchment Sediment Connectivity And DElivery (CASCADE) modeling framework. In CASCADE, each sediment cascade establishes connectivity between a specific source and its multiple sinks. From a source perspective, the fate of sediment is controlled by its detachment and downstream transport capacity, resulting in a specific trajectory of transfer and deposition. From a sink perspective, the assemblage of incoming cascades defines provenance, sorting, and magnitude of sediment deliveries. At the network scale, this information reveals emerging patterns of connectivity and the location of bottlenecks, where disconnectivity occurs. In this paper, we apply CASCADE to quantitatively analyze the sediment connectivity of a major river system in SE Asia. The approach provides a screening model that can support analyses of large, poorly monitored river systems. We test the sensitivity of CASCADE to various parameters and identify the distribution of energy between the multiple, simultaneously active sediment cascades as key control behind network sediment connectivity. To conclude, CASCADE enables a quantitative, spatially explicit analysis of network sediment connectivity with potential applications in both river science and management. [ABSTRACT FROM AUTHOR]

In fact, our pyrogenic carbon dates of the silt-sized charcoal fraction (though not many available) show mid-Holocene dates within the top 40 cm of the ADE, and there was no increase in pyrogenic carbon moving upward within the ADE soil profile, as would be expected if there were large charcoal inputs in the late Holocene from human activity. Lombardo et al. offer no explanation to our finding of C isotope ratios that indicate a savanna component prior to human occupation in the ADEs but not in the adjacent soils. B replying to b Lombardo et al. I Nature Communications i https://doi.org/10.1038/s41467-022-31064-2 (2022) Amazonian Dark Earths (ADEs) are widely regarded as a model for sustainable agriculture. Their unusual fertility and elevated concentration of charcoal, combined with the frequent occurrence of pre-Columbian artifacts at ADE sites, has prompted widespread biomass burning for soil amendment in tropical regions. [Extracted from the article]

The paper presents the petrological and geochronological studies of migmatite from an important section of Higher Himalayan Crystalline Sequence of Eastern Himalaya. Migmatites collected from the area characteristically contain biotite‐garnet‐sillimanite‐plagioclase‐K‐feldspar‐quartz as an important mineral assemblage, which has experienced extensive partial melting through dehydration melting reaction involving biotite. In this study, P–T evolution of these migmatites has been constrained through the use of multiequilibrium thermobarometry program winTWQ, conventional thermobarmetry, and pseudosection modelling in the MnNCKFMASHTO model system using Perple_X software. The unification of these three calculations demonstrates that the migmatite experienced peak pressure and temperature at 7.2 ± 0.5 kbar and 775 ± 20 °C, respectively. SHRIMP U–Pb chronological results yield the timing of crustal melting (21 Ma) in the migmatite. [ABSTRACT FROM AUTHOR]

Confluences are dynamic morphological nodes that are found in all river networks. In mountain regions, they are influenced by hydraulic and sedimentary processes that occur in steep channels during extreme events in small watersheds. Sediment transport in the tributary channel and aggradation in the confluence can be massive, potentially causing overbank flooding and sedimentation into adjacent settlement areas. Previous works dealing with confluences have mainly focused on lowland regions, and those that have focused on mountain areas have used sediment concentrations and channel gradients that are largely under-representative of mountain river conditions. The presented work contributes to filling this research gap with 45 experiments that use a large-scale physical model. Geometric model parameters, the applied grain size distribution, and the considered discharges represent the conditions at 135 confluences in South Tyrol (Italy) and Tyrol (Austria). The experimental program allowed for a comprehensive analysis of the effects of (i) the confluence angle, (ii) the tributary gradient, (iii) the channel discharges, and (iv) the tributary sediment concentration. In contrast to most research dealing with confluences, results indicate that, in the presence of an intense tributary sediment supply and a small tributary-to-main-channel discharge ratio (0.1), the confluence angle does not have a decisive effect on confluence morphology. Adjustments to the tributary channel gradient yielded the same results. A reoccurring range of depositional geomorphic units was observed in which a deposition cone transitioned to a bank-attached bar. The confluence morphology and tributary channel gradient rapidly adjusted, tending towards an equilibrium state to accommodate both water discharges and the sediment load from the tributary. Statistical analyses demonstrated that the confluence morphology was controlled by the combined channel discharge and the depositional or erosional extent was controlled by the sediment concentration. Applying conclusions drawn from lowland confluence dynamics could misrepresent depositional and erosional patterns and the related flood hazard at mountain river confluences. [ABSTRACT FROM AUTHOR]

The present paper deals with the historical evolution of the northern Bay of Cádiz (SW Spain) between the last eustatic maximum (6.5 ka BP) and the present day, by means of a series of independent proxies. The zone is constituted by the tidal estuary of the Guadalete River, filled with saltmarsh sediments during the late Holocene, due to the sheltering of the zone by a confining outer sandy barrier. The northern border of the Bay records an urban settlement of Phoenician Age (first millennium BC), Doña Blanca. A detailed survey was made in the contact between the Phoenician city and the saltmarshes in order to detect other possible urban structures related to the morphological and sedimentary evolution of this environment during historical times. Two campaigns with GPR Stream-X array were carried out as well as aerial imaging and topographic survey with UAV. In parallel, a total of 8 boreholes were made in different parts of the saltmarshes, including radiocarbon dating of selected samples for estimating sedimentation rates in the saltmarshes. Results obtained by georadar prospection and UAV survey revealed the presence of a second urban settlement on the marginal sedimentary plain, very probably installed upon a sandy fluvial island of the Guadelete River. The urban remains, of Punic Age, are partly covered by clay sediments due to the subsequent evolution of these saltmarshes, where sedimentation rates of up to nearly 2.4 mm/yr have been estimated for environments close to fluvial and/or tidal channels and hence more affected by sediment aggradation during flooding episodes. In recent times, river regulation by dams and the artificial desiccation and cropping of the saltmarshes have interrupted the natural trend of the area towards sedimentary silting up. [ABSTRACT FROM AUTHOR]

This paper presents new sedimentological, geomorphological, and optically stimulated luminescence (OSL) geochronological evidence for fluvial evolution of the mid- to lower River Tyne through the Lateglacial to late Holocene. These data reveal a series of fluvial terraces produced by cycles of aggradation and incision, conditioned by glacial inheritance and driven by changing sediment availability and hydrological regime. The distribution and stratigraphy (where available) of nine river terrace and their associated sediments have been recorded. At two key sites the sediments have been dated using OSL measurements to constrain the fluvial geomorphology. Significant entrenchment of the fluvial system, followed by aggradation formed the earliest fluvial terrace (T1), which encompasses environments spanning the transition from deglaciation into Greenland Interstadial 1 (GI-1). Incision below T1 began towards the end of GI-1, with three terraces (T2 – T4) between the abandonment of T1 and the early Holocene (15.0–9.2 ka). Climatic shifts, limited vegetation cover/soil development, and peri −/paraglacial landscape instability conditioned the development of the early postglacial fluvial landsystem. Three further terraces (T5 – T7) developed during the mid- to Late Holocene (6.6–3.1 ka), and comprise most of the valley floor. Climatic instability, glacial inheritance, and widespread anthropogenic disturbances are reflected in greater hillslope-channel coupling during this period. The extent of later Holocene terraces (T8 – T9) is limited as the river became isolated from flanking hillslopes entrenched between existing river terraces. Fluvial landscape evolution in formerly glaciated catchments is strongly conditioned by the cold stage legacy that introduced excess sediment and landscape instability into the catchment. Subsequent catchment-wide responses are variable and non-linear, with valley floors operating in a series of reach-wide responses. There is a need for greater chronological control to constrain the Lateglacial and Holocene evolution in the Tyne catchment, but also to further our understanding of region-wide responses to external drivers and local dynamics. • Lateglacial to late Holocene fluvial response recorded from river terrace sequence. • Fluvial landscape strongly conditioned by glacial legacy. • Catchment-wide responses are non-linear and valley floors operated as reach-wide responses. • River responded to climate and/or landscape perturbations at ∼16, 11.9, 8.7, 4 ka. [ABSTRACT FROM AUTHOR]

Incised marine valleys (IMVs) are fruitful targets of stratigraphic-based exploration within low-stand system tracts (LSTs). The narrowband volumes constrain the quantification of density, velocity, thickness, lithology, and possible fluids for successful hydrocarbon exploration. This study quantified IMVs using quantitative digital tuning frequency-based seismic volume (DFSV) and tuned frequency-based instantaneous lateral porosity-decomposed inverted density reservoir simulations (LPDS). The seismic amplitudes and reflection strength attributes have imaged medium- to coarse-grained sandstone lenses along the southwestern and westernmost flanks of this gas field. The 24-Hz DFSV imaged a 35 km2 stratigraphic prospect in the aggradation parasequences of fluvial source point bars. The LPDS resolved 7-m-thick gas-bearing reservoirs through blocky gamma-ray signatures. The cross-plot of pseudo and simulated physical parameters showed an R2 of > 0.90 for developing stratigraphically-trapped IMVs in the LSTs, confirming a very high potential of clastic systems for generating hydrocarbons because the reservoir has 1.6–1.8 g/cm3 density of fractured and 23–32% highly porous reservoirs. With strong R2 of > 0.95, an extensive improvement in accommodation space was observed in the porosity range of 23–32% and thickness range of 7–10 m. As a broader implication, there were regionally developed and reduced accommodating spaces of gas-bearing reservoirs within 23–32% porosity range and ~ 10–17% porosity zones. The zones of reductions in accommodation space were under the strong influence of sea-level rise due to compacted sedimentary facies with porosity range of 10–17%, which is equally an analogy aimed at global extensional geology. [ABSTRACT FROM AUTHOR]

Understanding the future evolution of permafrost requires a better understanding of its climatological past. This requires permafrost models to efficiently simulate the thermal dynamics of permafrost over the past centuries to millennia, taking into account highly uncertain soil and snow properties. In this study, we present a computationally efficient numerical permafrost model which satisfactorily reproduces the current ground temperatures and active layer thicknesses of permafrost in the Arctic and their trends over recent centuries. The performed simulations provide insights into the evolution of permafrost since the 18th century and show that permafrost on the North American continent is subject to early degradation, while permafrost on the Eurasian continent is relatively stable over the investigated 300-year period. Permafrost warming since industrialization has occurred primarily in three "hotspot" regions in northeastern Canada, northern Alaska, and, to a lesser extent, western Siberia. We find that the extent of areas with a high probability (p3m>0.9) of near-surface permafrost (i.e., 3 m of permafrost within the upper 10 m of the subsurface) has declined substantially since the early 19th century, with loss accelerating during the last 50 years. Our simulations further indicate that short-term climate cooling due to large volcanic eruptions in the Northern Hemisphere in some cases favors permafrost aggradation within the uppermost 10 m of the ground, but the effect only lasts for a relatively short period of a few decades. Despite some limitations, e.g., with respect to the representation of vegetation, the presented model shows great potential for further investigation of the climatological past of permafrost, especially in conjunction with paleoclimate modeling. [ABSTRACT FROM AUTHOR]

This paper develops a numerical model for the analysis of sediment transport in irrigated channels. The overland flow equation considers infiltration into the subsurface. The model solves Saint Venant and sediment continuity equations to analyze overland flow and sediment transport, while Richard's equation is used to analyze subsurface flow. Saint Venant and sediment continuity equations are solved using MacCormack-scheme-based finite-difference method and Richard's equation is solved using a mass conservative fully implicit finite-difference method. The model is validated by comparing model-predicted aggradation with experimental observations. The model is used to study the effect of infiltration on aggradation of a channel bed during sediment-laden flows. It was observed that infiltration significantly affects and alters the aggradation phenomenon and aggradation considering infiltration is found to be higher than that without considering infiltration. Among the different unsaturated soil parameters, the saturated hydraulic conductivity and initial dryness of the soil were found to be the main factors affecting the sediment transport in irrigated channels. [ABSTRACT FROM AUTHOR]

Typically, the analysis and design of fluvial flood defence schemes is based on a single N year extreme flow event using a single survey of the river channel and flood plains. Adopting this approach assumes that the channel capacity is identical for all subsequent N year events. If one assumes that the typical design life for a flood defence scheme is of the order of 50 years, then such an approach is flawed because river channel morphology, and hence flood conveyance, may change considerably over this time scale. Therefore, to provide a more robust estimate of future flood inundation, a sensitivity analysis of these changes should be undertaken. This paper proposes a modeling methodology that combines a stochastic model, for estimating streamflow throughout the design period, and a 1D sediment transport model (HEC-RAS), to enable this sensitivity to be included in flood inundation modeling and defence scheme design. The methodology is demonstrated through conceptual implementation to evaluate the change in water surface elevation (WSE) along an alluvial river (River Caldew, England) reach after 50 years of sediment transport. Changes in WSE are assessed when the reach is natural (no flood defences) and modified (with idealized flood defences). Results show that the construction of the flood defence scheme does not alter the overall morphological pattern of the reach but can significantly increase (260%) local aggradation. Additionally, 50 years of morphological change have the potential to increase WSE such that high flows, previously confined within the channel, can overtop the banks and become flood events; and that, the standard freeboard levels of the flood defence scheme may be insufficient to prevent overtopping when morphological change is considered. The method can be considered as a semiquantitative modeling methodology to account for the sediment-related sensitivity of flood risk management; and provides valuable insights into the potential magnitude that this has on future flood inundation. [ABSTRACT FROM AUTHOR]

In this paper a sensor data fusion approach for characteristics field monitoring, based on time variance control model, is proposed. Distributed sensing and remote processing are the basic features of the employed architecture. In fact, in order to obtain meaningful information about the temporal and spatial variations, which characterize the field levels of some characteristics (electromagnetic, air pollution, seismic, etc), a distributed network of wireless and mobile smart-sensors has been designed.Starting from the partitioned configuration of a monitored geographic areas, this model allows to take into account the different levels of degradation over time in the sensors' performances associated with the different geographic partitions, progressively increasing the severity of the control. To this end, through the introduction of a reliability curve, a revised traditional control chart for variables is proposed.The proposed approach, further constituting an element of the scientific debate, aims to be a useful operational tool for professionals and managers employed in the environment control. [ABSTRACT FROM AUTHOR]

Tributary-junction alluvial fans situated at the intersection of confined valleys with <100 km2 tributary catchments are of special interest to evaluate the heterogeneous consequences of extreme rainfall events in arid zones. These fans record the episodic sedimentological behaviour of the hillslope response to rainstorm events within tributary catchments, together with the influence on the main fluvial systems. In this paper, we benefit from the March 2015 event (23–26 March 2015), which produced 75–46 mm of precipitation over four days in the southern portion of the Atacama Desert. This storm event triggered several debris flows in El Huasco River watershed tributaries and, therefore, tributary-junction alluvial fans received a total of ∼106 m3 of sediments across 49 activated catchments. We find that the characteristic storm signature across the catchments can be synthetised in a conceptual fan formation model based on field mapping of facies (F1 to F6) present in the fans. The characteristic signature is a record of initially high sediment-to-water flows restricted to the fan environments (mainly debris flows) followed by later, more dilute (mainly hyper-concentrated to fluvial) flows that incise the tributary-junction alluvial fan deposits and link tributary catchments with the main river. These later-stage flood event deposits, locally, are capable of ponding and compartmentalising the main river where the longitudinal connectivity of the tributary-junction catchment is effective. This situation improves tributary-junction fan slope and main-trunk-channel linkages. This approach provides a reference framework for understanding the distribution and routing of effective runoff from similar rainfall events that control the aggradation and incision of the fluvial system, which is of great value when studying past stratigraphic arrangements in these arid alleys. [ABSTRACT FROM AUTHOR]

Regulated rivers usually subjected to continuous morphological changes due to human interventions and the variation of the flow rates released through them. These changes sometimes affect island banks causing bank failure and deformation. On the other hand, the morphological changes cause the riverbed to aggrade/degrade. This, in turn, may affect the carrying capacity and conveyance of the river channel. To keep the channel conveyance as efficient as possible, bed aggradation should be minimized. This paper basically aims at increasing the efficiency of the River Nile western branch at Warrak Island. Eight scenarios are proposed to achieve this goal, which includes removing the unmanaged human intervention at the island southern nose, dredging the western branch to the safe navigation elevation (12.66 m) and propose a development plan for canalization of this branch. A 2-D numerical model (Delft 3D) was used to simulate this segment of the river to detect and predict the trend of the morphological changes. The ratio of flow passes through this branch is calculated for all cases, it was found to be 31.4% for the current case, while the maximum value of 45.52% occurred when removing of the southern part of the island nose and dredging the branch is applied. The morphological changes were predicted, and it is found that the entrance of the west branch is always subjected to sedimentation due to the general alignment of the river in this region. Results also indicates, for development scenarios, that deposition also occurred in the entrance of the west branch, like before, but the dredging was limited to few locations, which can be handled with dredging. So, it is recommended, in case of using the west branch for navigation in an emergency case, to follow the development of the west branch as a solution. [ABSTRACT FROM AUTHOR]

• Rapid geomorphological evolution occurred in the erodible lithology and semiarid climate of southern Italy. • A deposition phase during the Little Ice Age (LIA) was the last global cold climatic phase. • Badland incision occurred during Mediaeval Warm Period and continued in stably alternating phases until 1700 CE. • Valley aggradation ended early in 1850 as a phase of historic arroyo cutting began. • Geomorphological evolution around Basilicata during the LIA was very rapid and controlled by extreme surface process sensitivity to climate change. There is a general consensus that the increased frequency of extreme climatic events will quickly change the morphology of the landscapes in the Mediterranean area. Knowing and understanding the expected changes becomes crucial for defining future adaptive strategies. This paper deals with the very rapid geomorphological evolution in an emblematic Mediterranean area, the Basilicata region of southern Italy, during the last 300 years. The results show that the landscape evolution was mainly controlled by the extreme sensitivity of surface processes to climate change. Landslides, a new cycle of the formation of badland landforms such as calanchi and biancane, and an aggradation/incision phase in the main river valleys have completely reshaped the landscape of the Bradanic Trough, whereas fresh eroded material was moved to the coast. New data on valley-fill alluvium in the Basento River and one of its main left tributaries, the Vella stream, show ages ranging from 1700 to 1850. This deposition phase coincides with the Little Ice Age, an epoch of global climate variability. Previous literature showed that the alluvium of this age consists of a mappable stratigraphic unit outcropping in all the large alluvial valleys of the Basilicata and Mediterranean regions. Palaeoclimate and high-resolution palaeoflood data indicate that valley-fill alluviation occurred during a long humid period. Valley aggradation ended in approximately 1850 with the beginning of a new phase of historic arroyo cutting, mainly due to high magnitude-low frequency rainy events within prolonged drought periods. The stream incision drew the terminal dissection of the clayey slopes into biancana rounded morphologies. These data seem to be confirmed by the comparable heights of about 3 m, both of the biancane and of the fluvial terraces. [ABSTRACT FROM AUTHOR]

The size and geometry of river channels play a central role in sediment transport and the character of deposition within alluvial basins across spatiotemporal scales spanning the initiation of grain movement to the filling of accommodation generated by subsidence. This study compares several different approaches to estimating palaeoflow depths from fluvial deposits in the early Palaeogene Willwood Formation of north‐west Wyoming, USA. Fluvial story heights (n = 60) and mud plug thicknesses (n = 13) are statistically indistinguishable from one another and yield palaeoflow depth estimates of 4 to 6 m. The vertical relief on bar clinoforms (n = 112) yields smaller flow depths, by a factor of ca 0.3, with the exception that the largest bar clinoforms match story heights and mud plug estimates. This observation is consistent with modern river data sets that indicate unit bar clinoforms do not capture the reach‐mean bank‐full flow depths except in rare circumstances. Future studies should use story heights (i.e. compound bar deposits) and mud plugs to estimate bank‐full flow depths in alluvial strata. Additionally, the thickness of multi‐storied fluvial sandbodies (n = 102) and overbank cycles composed of paired crevasse splay and palaeosol deposits (n = 45) were compared. The two depositional units display statistically indistinguishable mean and median values. Building upon previous depositional models, these observations suggest basin rivers aggraded approximately one flow depth prior to major avulsion. This avulsion process generated widespread crevasse splay deposition across the floodplain. Once the main river channel stem was reestablished, overbank flooding and palaeosol development dominated floodplain settings. The depositional model implies river aggradation autogenically generated topography in the basin that was effectively filled during the subsequent avulsion. This constitutes a meso‐timescale (103–104 years) compensational pattern driven by morphodynamics that may account for the high completeness of fossil and palaeoclimate records recovered from the basin. [ABSTRACT FROM AUTHOR]

The formation of the Jinsha River drainage is a significant subject of concern in the geological and geomorphological fields. Among them, one key question is whether there was a regional paleo lake into which Lower Jinsha River drainage drained during the late Pliocene to early Pleistocene, due to massive fluvio-lacustrine sediments widely distributed in the Lower Jinsha River. Nevertheless, there has yet to be a consensus on the genesis of those fluvio-lacustrine sediments due to poor sedimentological and chronological data. In this study, to unravel the origin of those fluvio-lacustrine sediments and the formation model of the Lower Jinsha River, sedimentary characteristics, including spatial distribution, lithological composition, and stratigraphic contact relationship of those fluvio-lacustrine sediments were analyzed, and chronological determination of the fluvio-lacustrine sediments using Electron Spin Resonance and Optically stimulated luminescence method was conducted. The results show that in the Lower Jinsha River, the lacustrine sediments are mainly composed of silt and clay, with apparent horizontal bedding, stacked with fluvial cobble-gravel and sand, and are in unconformable contact with the underlying bedrock strata or paleo soil. The lacustrine sediments are spatially discontinuous and mainly distributed in the Shigu, Taoyuan, Panzhihua, and Longjie reaches. Downstream of these reaches are deeply incised gorges with an average slope >30°, and many landslide landforms and deposits can be identified here. In each reach, the lacustrine sediments were closely distributed along the trunk and tributary channels in the plane and were distributed at different altitudes, forming a sequence of lacustrine terraces. Chronological analysis shows that in different reaches, the deposition ages of lacustrine sediments are significantly different. In each reach, the deposition age of the lacustrine terraces of high altitude is older than that of low altitude. The above characteristics collectively indicate that the lacustrine sediments in the Lower Jinsha River were locally deposited by individual dammed lakes, probably induced by landslide rather than a regional paleo lake by tectonic activities. During the incision process of the river valley, landslides continuously block the river channel, forming dammed lakes, and then deposited lacustrine sediments at different elevations, forming lacustrine terraces. The lacustrine sediment of the topmost lacustrine terrace in Panzhihua reach was dated to be 1.78 Ma, combined with previous studies on the fluvial terraces, indicating the Lower Jinsha River existed and started to incise its valley before the early Pleistocene. The widespread dammed lake sediment indicates that the formation of the Jinsha River valley follows the pattern of "incision-landslide-damming-aggradation-incision". [ABSTRACT FROM AUTHOR]

The rates of incision and aggradation in the channels in the Terek River basin (North Caucasus) for the last 50–85 years were estimated at 18 gauging stations. The stage–discharge method (annual low water stages at the same discharges) was applied. The stability of the Terek River channel was recorded on the tectonically subsiding Tersko–Kuma Lowland. On the subsiding Kabardian Plain, channel aggradation up to 14 mm a−1 was registered. The rapid (~32 mm a−1) incision of the Terek River occurs within the antecedent valley of the rising Sunzha Ridge, causing regressive erosion and incision (~25 mm a−1) of rivers on the Ossetian Plain, despite its tectonic subsiding. The rivers in the uplifting mountains of the North Caucasus transport the sediments delivered from slopes as climatically controlled debris flows. Aggradation and incision here alternate without a visible overall trend. The rates of modern channel bed deformations are 10 to 100 times higher than the mean rates of tectonic movements. The main effect of tectonics is the changes in river channel slopes, which cause changes in the bed load transport budget and channel bed deformation. Human-made constructions induce rapid deformations in the channels but have a local effect. [ABSTRACT FROM AUTHOR]

A numerical modelling investigation of bed aggradation in open rectangular drainage channels is presented in this paper. A semi-coupled modelling approach for uniform sediments based on 1D-shallow water De Saint Venant - Exner equations was adopted to describe the temporal evolution of the bed in the deposition and transport phenomena associated with aggradation process. Six well-established sediment transport formulas were used to evaluate the sediment discharge over the aggrading bed. Simulations enabled the comparison of results obtained with the selected formulas against a comprehensive set of experimental measurements reported in the literature. Results have shown the adopted model to describe successfully the evolution of sediment bed and water level profiles during the aggradation experiments, with minor differences depending on the used sediment transport relationship. [ABSTRACT FROM PUBLISHER]

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Floodplain sedimentation is one of the most dynamic geomorphic processes within plain and lowland landscapes. There is generally a good understanding of longer term floodplain evolution, but quantitative information on overbank deposition rates for recent shorter timescales is lacking. This paper describes the application of Chernobyl-derived 137Cs to quantify floodplain aggradation rates for the River Plava (a small river draining a severely contaminated part of the upland region of Central European Russia), based on detailed sampling of four representative floodplain study sites. Two approaches have been employed for estimating post-Chernobyl (1986-2009) floodplain accumulation rates. The first was based simply on locating the Chernobyl fallout-associated 137Cs peak in overbank sediment sections. The second involved quantification of the increase in the total 137Cs inventory at individual sampling points associated with the post-Chernobyl deposition of contaminated suspended sediment. It has been shown that considerable local-scale variability of overbank deposition rates exists, with aggradation rates on the low level floodplain (6 ± 1.2-14 ± 2.8 mm year−1) exceeding by 1.5-3 times the values for the middle level floodplain (2 ± 0.4-9 ± 1.8 mm year−1) and by 3-6 times the values for the upper level floodplain (1 ± 0.2-5 ± 1.0 mm year−1) floodplain levels. Combining these estimates with information on the areas occupied by different floodplain levels within the 54 km long valley section, derived from detailed geomorphic surveys of the selected reaches, it has been estimated that about 9700 ± 1950 t of sediment have been stored on floodplain during the 1986-2009 period. The role of floodplain storage in the overall basin sediment budget and conveyance losses within the main channel system have been evaluated. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The Belt of Schuppen (BoS) of Nagaland is a NE-SW trending linear zone lying adjacent to the Brahmaputra Valley of Assam in Northeast India. Geomorphic, stratigraphic and chronologic data from the Dzüdza and Chathe river valleys that cut across the BoS have been studied to understand the influence of climate on landform evolution in parts of the BoS. Fluvial landforms in the Dzüdza and Chathe river valleys evolved in four major phases bracketed between 22–17 ka (Phase IV), 13–9.0 ka (Phase III), 7–5 ka (Phase II) and 3.5–1.5 ka (Phase I), indicating multi-centennial to millennial changes in monsoon intensity. Climatically, Phase-III was dominated by valley aggradation initiated by onset of the Indian Summer Monsoon (ISM) and persisted intermittently till the early Holocene-strengthened ISM. The other phases of aggradation are attributed to transient or weak ISM. The present study suggests that fluvial aggradation was associated with enhanced precipitation and sediment supply in the BoS valley, whereas the transient and weak ISM is manifested in episodic pulses of alluvial ingression from the tributaries to the trunk valleys; along with post depositional tectonic modifications of the landforms. [ABSTRACT FROM AUTHOR]

River corridors along non‐perennial stream networks provide diverse physical and ecological functions that are thought to be related to the spatial and temporal variability of geomorphic units, also known as geomorphic heterogeneity. While studies on the characteristics and drivers of geomorphic heterogeneity have been developed in perennial streams, similar studies in ephemeral streams are lacking. Given the ubiquity of non‐perennial streams globally, we aim to answer questions regarding the magnitude and drivers of geomorphic heterogeneity in ephemeral river corridors as well as how geomorphic unit assemblages reflect processes related to flood disturbance. Geomorphic units were mapped in 30 unconfined river corridors within six non‐perennial watersheds in Utah and Arizona, USA. Landscape heterogeneity metrics—Shannon's Diversity Index, Shannon's Evenness Index, and patch density—were used to quantify geomorphic heterogeneity within each reach. Additionally, variables that potentially constrain or drive heterogeneity were quantified, including floodplain shape, grain size, large wood abundance, and proxies for flood disturbance. While heterogeneity positively correlated with metrics for morphology and disturbance, statistical models suggest that morphologic context, particularly river corridor width, was a more important predictor for estimating geomorphic heterogeneity. Still, geomorphic units reflected aggradation processes indicative of a range of flood energies, suggesting a strong tie between heterogeneity and disturbance. Results suggest that geomorphic heterogeneity may be resilient to changes in flood disturbance frequency or magnitude, but future studies investigating long‐term temporal heterogeneity are needed. Plain Language Summary: Rivers and floodplains that flow only temporarily are common in dry environments and support important habitat and other ecosystem functions in deserts. These functions are thought to be tied to the variability of physical forms, such as elevation and sediment grain size, within the river and floodplain. However, physical variability or diversity is understudied in dry, temporary rivers. Here, we measured the range and potential factors that influence physical variability in 30 temporary rivers and floodplains in Utah and Arizona, USA. Potential controlling or influencing factors, including the size of the floodplain as well as evidence of flooding, were also measured in each study area. Results show that river corridor width—not estimates of flooding—has the most important control on physical variability, where wider river corridors have a greater diversity of patches. Results suggest that physical diversity and associated functions may be resilient to future changes in flooding due to climate change. Key Points: Geomorphic heterogeneity, morphology, and flood disturbance proxies were characterized in 30 floodplains along ephemeral streamsRiver corridor width had a stronger influence on diversity metrics than proxies for flood disturbanceGeomorphic heterogeneity in non‐perennial river corridors is similar to values previously measured in perennial watersheds [ABSTRACT FROM AUTHOR]

From 300 BC to AD 300, the city of Pergamon underwent a profound transformation that impacted the rural settlement patterns and the concomitant geomorphodynamics. We present a geoarchaeological study in a long-term settled catchment in the Pergamon micro-region to disentangle the Holocene geomorphodynamics and triggering factors, for example, climate change and human activity. The analyses of eight radiocarbon-dated sediment profiles from the Tekkedere alluvial fan and its catchment indicate four principal sedimentation phases. Phase 1 (ca. 6.2 to 5–4 ka) is dominated by the floodplain aggradation of the receiving Bakırçay River, which is followed by the formation of floodplain soils (phase 2). Substantial geomorphodynamic changes occurred around 4 ka (phase 3), when the edge of the floodplain was buried by fan sediments of the tributary Tekkedere creek. This is attributed to supraregional aridization and rapid climate change events, superimposed by the onset of local human activities. Repeated cycles of coarse- and fine-textured fan sediments with age inversions after ca. 3.8 ka and valley infills younger than 1300 yr BP indicate the strong erosion and redeposition of sediments in phase 4. These increased geomorphodynamics may coincide with the changing settlement pattern and thus reflect human–environment interactions. [ABSTRACT FROM AUTHOR]

This article is focused on the specific vegetation, which has formed from the floodplain forests on the aggradation mound (elevated sediment deposition) along the original Danube river in Slovakia in the part affected by Gabčíkovo waterworks that was put in operation in 1992. As a result of water regime changes, when a major part of the Danube water flow was redirected to the Gabčíkovo hydroelectric power plant, original floodplain forests on the aggradation mound began to suffer from a water deficit, which is also supported by shallow soils formed mostly on the gravel sediments with limited capillary rise of groundwater. It has triggered successional processes leading to the degradation of forest with changes in all layers. To identify these changes and development trends, we analyzed vegetation data from 2002, 2012, and 2022. The results indicate that the process of secondary succession of the original floodplain forest continues. This includes mainly an increase in the number of species, especially those typical for grasslands and synanthropic habitats. From an environmental point of view, the spread of some invasive species is striking. Ordination method (canonical-correlation analysis [CCA]) confirmed light, moisture, number of species, and Shannon–Wiener index as the main factors determining relevés' variability. [ABSTRACT FROM AUTHOR]

The fluvial geomorphology and stratigraphy on the middle Snake River at Bancroft Springs, Idaho, provide evidence for numerous episodes of Snake River aggradation and incision since the Bonneville Flood at ca. 18 ka. A suite of seven terraces ranging from 20–1 m above modern bankfull elevation records multiple cut-and-fill cycles during the latest Pleistocene and Holocene in response to local base-level controls, variations in sediment supply, and hydroclimate change. Radiocarbon and luminescence dating show that the ages of fluvial aggradation generally coincide with increased sediment supply and likely wetter hydroclimate during onset of the Younger Dryas stadial (ca. 13.2 ka), deglaciation and termination of the Younger Dryas stadial (ca. 11.3 ka), Early Holocene cooling (ca. 8.8 ka), and Neoglacial (ca. 4.5, 2.9, 1.1 ka). Six intervening periods of incision and channel stability may also reflect either reduced sediment supply, drier hydroclimate, or both. The terrace chronology can be correlated to a variety of local and regional paleoclimate proxy records and corresponds well with periods of continental- and global-scale rapid climate change during the Holocene. The fluvial record demonstrates the geomorphic response and sensitivity of large river systems to changes in hydroclimate variability, which has important implications for inferring paleoenvironmental conditions in the region. [ABSTRACT FROM AUTHOR]

Archaeologists frequently invoke climate change as a driving cause for ancient expansions of human populations, but geomorphic changes can also play an important role in opening or closing routes of migration. In China, archaeological evidence demonstrates that valleys in the Jialing River's watershed were important routes for the movement of Neolithic populations from the catchments of the Yellow River to the Yangtze River. Here, we examine how fluvial geomorphological regime shifts may have also influenced the migration pathways and adaptive strategies of Neolithic people into the Sichuan Basin by using a combination of sedimentological and palynological analysis at Luojiaba, an archaeological site located on one of the eastern tributaries of the Jialing River. The results show that people settled on seasonally stable landforms, including the Zhonghe River floodplain at Luojiaba (5300–4800 cal. B.P.). They carried out fishing and hunting activities on the front edge of the floodplain close to the river channel and built dwelling features on the higher ground at the back edge of the floodplain, which was not affected by seasonal floods. We hypothesize that during the Holocene Climatic Optimum before 5500 cal. B.P., high water levels as well as severe surface erosion caused by a strong East Asian Summer Monsoon (EASM) blocked pathways into the upper reaches of the Jialing River watershed. Only after a series of cold, dry climate events driven by a decrease in EASM intensity ca. 5500–5000 cal. B.P. did water levels recede significantly. This allowed alluvial aggradation to occur, which created floodplains and terraces along the valley that may have opened a new route for the migration into the Sichuan Basin. Our results reveal the human–environment dynamics surrounding Luojiaba in the uplands of southwestern China and highlight the impact of coupled climatic‐geomorphic regime shifts on human settlement and subsistence strategies, across both space and time. [ABSTRACT FROM AUTHOR]

Packages of fluvial systems in the Lower Ganga plains (LGP) archive the changes in stratigraphic architecture induced by perturbations in the climatic system. In some parts of this landscape, where the fluvial sequences predominate, the role of climate in landsculpting is strongly indicated by the presence of sediment architecture. The present study is focused on the formation of alluvial plains of the Ajay River in the Rarh region that represent a region's environmental templates for understanding the landscape of LGP. The sedimentological, geomorphological, and optically stimulated luminescence (OSL) chronological investigations were attempted to document sedimentation patterns and the timing of deposition. The stratigraphic data from two exposed cliff sections and three boreholes are compared with proxy records to understand the Indian Summer Monsoon (ISM) controls on alluvial sedimentation for the last ~2.4 ka. The fluvial packages in the study area correspond to two significant channel phases: Period‐I (2.4–1.3 ka) and Period‐II (800–200 years ago). Period‐I is characterized by the episodes of floodplain development and lateral migration of the trunk river during Marine Isotope Stage (MIS) I, especially around 2 ka corresponding to the Roman Warm (RW) period in the Indian subcontinent. The sediment filling was high during ~2.4 ka due to ISM intensification, but in the later stage, the sedimentation was at a fairly steady rate. Conversely, Period‐II is characterized by flooding phenomena and aggradation of channel bodies across much of the present valley area during the last 800 years. The distinct flood events occurred during the times of significant shifts in ISM, from fluvial dormancy to sudden outbursts of monsoons (end of Little Ice Age [LIA] ~ 19th century), indicating that climatic patterns can be associated with the occurrences of abrupt flood events. The alluvial records fit well with the historical, instrumental, and published proxy data on the ISM validating the chronology and the potential of sedimentary archives for further studies related to the palaeoenvironment and palaeogeography. [ABSTRACT FROM AUTHOR]

The “tablelands” in Taiwan are sedimentary terraces occurring in the foreland basin west of the Neogene mountain ranges. The Miaoli Tableland consists of elevated Late Quaternary sedimentary successions, representing a change from tidal to coastal and fluvial to eolian depositional environments. The present-day morphology is a result of combined processes, including differential tectonic uplift, ongoing fluvial aggradation, and incision. Selected deposits in 10 outcrops were sampled and studied by optical dating. The deposition of fluvial sediments started after the last interglacial (<100 ka) in the southeast of the tablelands. Uplift and sea-level lowering caused a base-level fall, resulting in a stepwise redeposition of the fluvial sediments. Additionally, enhanced remobilization of fluvial sediments occurred during the cold/dry climate during Marine Oxygen Isotope Stages (MIS) 4 and 2. The depositional ages of the coastal sediments enabled the estimation of long-term uplift rates of ca. 0.5 to 3.5 mm/yr. The eolian cover sediments yielded MIS 3 (east) to Holocene ages (west). Our results provide new insight into the interplay of climate, sea-level changes, remobilization of sediments, and tectonism leading to tableland formation during the Late Quaternary. [ABSTRACT FROM AUTHOR]

In fluvial networks, some confluences are associated with tributary-driven aggradation where coarse sediment is stored, downstream sediment connectivity is interrupted and substantial hydraulic and morphological heterogeneity is generated. To the extent that biological diversity is supported by physical diversity, it has been proposed that the distribution and frequency of tributary-driven aggradation is important for the magnitude and spatial structure of river biodiversity. Relevant ideas are formulated within the Link Discontinuity Concept and the Network Dynamics Hypothesis, but many of the issues raised by these conceptual models have not been systematically evaluated. This paper first tests an automated method for predicting the likelihood of tributary-driven aggradation in three large drainage networks in the Rocky Mountain foothills, Canada. The method correctly identified approximately 75% of significant tributary confluences and 97% of insignificant confluences. The method is then used to evaluate two hypotheses of the Network Dynamics Hypothesis: that linear-shaped basins are more likely to show a longitudinal, downstream decline in tributary-driven aggradation; and that larger and more compact basins contain more confluences with a high probability of impact. The use of a predictive model that included a measure of tributary basin sediment delivery, rather than symmetry ratio alone, mediated the outcomes somewhat, but as anticipated, the number of significant confluences increased with basin size and basin shape was a strong control of the number and distribution of significant confluences. Doubling basin area led to a 1.9-fold increase in the number of significant confluences and compact basins contained approximately twice as many significant confluences per unit channel length as linear basins. In compact basins, significant confluences were more widely distributed, whereas in linear basins they were concentrated in proximal reaches. Interesting outstanding issues include the possibility of using spatially-distributed sediment routing models to predict tributary-driven confluence aggradation and the need to gather ecological data sufficient to properly test for increases in local and network-scale biodiversity associated with significant confluences and their network-scale controls. [ABSTRACT FROM AUTHOR]

Lake St Lucia, the largest estuarine system in Africa, is enclosed by a 120 m-high compound Quaternary barrier-dune system in northern KwaZulu-Natal, South Africa. It comprises several discrete sedimentary basins within a single shallow back-barrier water body. This paper reports the first very-high-resolution seismic study of the system. Seven seismic units (A–G) are identified and interpreted based on their geometry, acoustic properties and a sediment coring programme. The units are bounded by regionally developed sequence boundaries and lower order unconformity surfaces corresponding to bay and tidal ravinement and hiatus surfaces. The lowermost subaerial unconformity formed during regression related to late-Pliocene hinterland uplift. Initial infilling of this surface in the proximal areas reflects estuarine sedimentation in a mixed wave- and tide-dominated system during the subsequent lowstand and early transgressive systems tracts, overlain by prograding highstand deltaic deposits that developed as sea-levels began to stabilise. Distally, this cycle of sedimentation is initially reflected by the infilling of a similar estuarine system that gradually transitioned to a back-barrier lagoon. Superimposed stillstands drove imbalances in the rate of sediment supply and accommodation space, and this, coupled with the development of an early barrier complex, caused lagoon aggradation and shallowing. A second similar trend is repeated for the recent postglacial sea-level cycle. There appears to be no preservation of the intervening Pleistocene cycles of erosion and deposition. The system is capped by estuarine-lacustrine deposits. The onset of lower energy estuarine-lake conditions began ~ 6235 cal BP in North Lake and started earlier in the proximal False Bay owing to sheltering by the antecedent barrier of a rocky peninsula. This study reveals a markedly different evolutionary history in adjacent basins of the same back-barrier system during two full sea-level cycles. These are attributed to a long established, non-migrating barrier, and to the influence of antecedent conditions on the system response to transgression. Unlike the US Atlantic margin, where migrating barriers truncate the infilling sequences, the main stratigraphic unconformities within each fill sequence correspond to tidal and bay ravinement surfaces. [ABSTRACT FROM AUTHOR]

Hydraulic characteristics of rill incipience on steep slopes with sandy soils are different from those of gentle slopes in the mountainous watersheds. In other to better understand the processes of the incision and expansion of rill, rainfall simulations were conducted in a laboratory soil box with an inflow device installed at the top of the steep slope. The location and shape of the rill incision were tested with respect to different slopes (20, 24, and 28°), rainfall intensity (80 and 100 mm/h), and segment distances with various inflow rates (0.0, 8.8, 17.5, and 26.3 ml/s). The result showed that rills with heatcut were mostly incised on the 2.4 m segments and progressively moved upslope on the 3.2 m segments. The steps of rill evolution with increase of inflow are identified as four stages; (1) sheet flow with impact of raindrops, (2) overland flow with flowpaths, (3) microrill with headcut incision, and (4) rill enhanced by headcut expansion. It appears that incision and headcut of rill is prevalent when the Froude number (Fr) changes from subcritical flow to supercritical flow and the maximum velocity of rill reaches over 0.065 m/s. Unit stream power using the maximum velocity of rill was the best parameter for estimating rill erosion as rill evolution greatly depends on maximum velocity of the local flow enhanced by rill incision and expansion As a result, it was found that critical conditions for rill incipient of sandy soils on steep slope are observed greater than those of loamy soils or gentle slopes. [ABSTRACT FROM AUTHOR]

The planform rearrangement of river basins is recognized as an important process for landscape evolution. The boundaries of river basins can shift either through gradual drainage divide migration or discrete river captures, but the methods for identifying these processes often rely on topographic evidence that remains otherwise untested. Moreover, efforts to understand the relative importance of either process are hampered by a lack of age constraints on river captures. We use 10Be‐derived erosion rates to test whether, and how, divide motion is occurring at three locations along the Blue Ridge Escarpment in the Appalachian Mountains. In the Pee Dee River basin, we find that the escarpment is migrating inland up to 45 m/Myr, consistent with topographic evidence for gradual divide migration. In the Dan River basin, erosion rates support the topographic evidence for river capture, and we use a forward model of river incision to estimate that the capture likely occurred in the past 12.5 Myr. In the South Fork Roanoke River basin, where the presence of a knickzone has been interpreted as evidence that a river capture initiated a pulse of faster erosion, we instead measure nearly uniform tributary erosion rates above and within the mainstem knickzone. Simulations show that river incision into a more erodible layer of rock, with or without a river capture, could produce the observed topography and erosion rates in the South Fork Roanoke River. Our results show how multiple lines of evidence can illuminate the rates and mechanisms of river basin reorganization. Plain Language Summary: River basins are dynamic features; they can grow and shrink over time through the gradual movement of drainage divides across a landscape, a process called divide migration. Alternatively, a river channel can abruptly change its flow direction, and connect with a channel in another river basin, in an event called a river capture. Divide migration and river capture are often identified using clues extracted from topography. Such topographic evidence indicates that the Blue Ridge Escarpment in the Appalachian Mountains is migrating toward the continental interior. In this study, we measure erosion rates on either side of the escarpment to test whether Atlantic‐draining rivers are eroding faster than those perched at higher elevations on the Mississippi side. In two out of three study sites the erosion rates are consistent with the topographic evidence. In the third site, the erosion rates are inconsistent with the physical evidence for river capture. We pair our measurements with computational simulations to show that a river eroding into different rock types can produce topography that alters the signature of river capture. Our results show that the Blue Ridge Escarpment is in motion, but that topographic interpretations can be complicated by the presence of multiple rock types. Key Points: Paired erosion rates across the Blue Ridge Escarpment show that the escarpment is migrating up to 45 m/Myr toward the continental interiorIn the Dan River, nonuniform erosion rates and simulations suggest a river capture occurred in the last 12.5 MyrUniform erosion rates in the Roanoke River show how incision into different rocks could obscure the topographic evidence of river capture [ABSTRACT FROM AUTHOR]

In the active tectonic setting of Aotearoa/New Zealand, large earthquakes are a relatively frequent occurrence and pose particular threats to infrastructure and society in Westland, on the west coast of South Island. In order to better define the medium- and long-term (annual to decadal) implications of these threats, existing dendrochronological data were supplemented by several hundred tree-ring analyses from 14 hitherto unstudied living tree stands in five catchments; these were combined to compile a regional picture of the location, extent, and timing of major prehistoric reforestation episodes on the floodplains of the area. These episodes correspond well with known dates of large earthquakes in the area (ca. 1400, ca. 1620, 1717 and 1826 AD), and their extents are thus interpreted to reflect the sediment deliveries resulting from coseismic landsliding into mountain valleys, and their reworking by rivers to generate widespread avulsion, aggradation, floodplain inundation and forest death. This regional aggradation picture can underpin anticipation of, and planning for, the medium- to long-term societal impacts of future major West Coast earthquakes. The source location of the next major earthquake in the region is unknown, so any of the Westland floodplains could be affected by extensive, up to metre-scale river aggradation, together with avulsion and flooding, in its aftermath, and these could continue for decades. Re-establishment and maintenance of a functioning economy under these conditions will be challenging because roads, settlements and agriculture are mostly located on the floodplains. The differences in floodplain vegetation between prehistoric and future episodes will affect the rapidity and distribution of aggradation; response and recovery planning will need to consider this, together with the impacts of climate changes on river flows. [ABSTRACT FROM AUTHOR]

Dynamism of river bed morphology is continuous and an integrated process of mountain's natural outflow in Himalayan Foothill Rivers. In-stream seasonal sediment flux, bridge establishments, bridge scouring and railway-road construction have detrimental influence over the natural flow regime of the river thereby causing channel degradation in the piedmont zone of eastern Himalaya of India, specifically near the urban areas where river management strategies are very weak. Such extreme anthropogenic events have a distinctive influence in changing river bed morphology in the middle-lower part of river Chel in Darjeeling Himalayan piedmont zone of India. Huge sediment aggradation and transportation networks historically have affected River Chel and have caused channel avulsion which poses a serious threat to the physical and ecological environment of Chel. Aggradation and lifting of sediments from the river bed are fatal for the geomorphologic character of the river, though no studies have been undertaken yet, to analyse the situation quantitatively in this regard. This paper presents evidence that suggests the changing river bed morphology, the dynamic nature of the river, the poor health of the river which is principally the impact of the seasonal sediment flux and bridge construction and thus some methods of river restoration in the middle-lower part of the river have been explained. Agglomeration of sediment, flow bifurcation, the volume of seasonal water mass, bed elevation changes and scouring are a major dynamic disposition for change of river bed morphology. Point bar, sidebar, braided active channel, ripples, and rise in the bed elevation are rapid changes in upper to lower part of bridges that are examined in the present study. In the dry season (December to February), a huge amount of sediment lifting makes incommodious man-made holes and a number of emergent channels which principally control the formation of a new active channel in the next monsoon season. The avulsion of major intra-active channels and morphological changes of the river bed for the last 85 years have also been observed in this study. Unlabelled Image • This paper presents evidence that suggests that the changing river bed morphology, the dynamic nature of the river, the poor health of the river is principally the impact of the huge sediment aggradation and bridge construction and thus some methods of river restoration in the middle-lower part of river Chel. • Suspended sediment, aggradation and degradation, Scouring calculation for boulder agglomeration, Compare of satellite images and Topographical map for braided channel shifting are major methods for understanding of outcome results. • Agglomeration of sediment, flow bifurcation, volume of seasonal water mass, bed elevation change and scouring are major dynamic disposition for change of river bed morphology by bridge construction scouring. [ABSTRACT FROM AUTHOR]