Search

Soil loss management requires reliable data for assessing the conditions prevailing in a watershed. Suspended sediment concentration (SSC) is one of the indicators of soil loss, and its data and associated properties are essential for integrated watershed management. However, until now, practical methods for estimating the temporal variation of SSC at the watershed scale, i.e., a sediment graph (SG), using measured data have been given less attention. Therefore, the current study was planned to simulate the SG through conceptual modeling of the soil erosion process and sediment yield. The Galazchai Watershed in West Azerbaijan Province, Iran, was selected as a case study. In this regard, the isochrone histograms were initially prepared using two methods of the longitudinal channel profile and spatially distributed travel time. Soil erosion was calculated in each isochrone segment using the Revised Universal Soil Loss Equation (RUSLE), applying the lumped and cellular automata approach. The soil erosion between isochrones was subsequently routed using the Hadley, WaTEM/SEDEM, and newly modified U.S. Forest Service methods. The last method was developed based on seven standardized variables for the current research. Synthetic SGs were ultimately derived from 12 different combinations of the study methods. The modeling performance was assessed using 38 storm events collected over several years. The base time, time to peak, peak value, and total sediment load of the simulated and observed SGs were evaluated using relative error. Comparison based on the evaluation indicators indicated better performance of the combination of the spatially distributed travel time method, cellular automata, and modified U.S. Forest Service method with the coefficient of efficiency and the normalized coefficient of efficiency varying from −1.16 to 0.99 and from 0.32 to 0.99 for the calibration and validation stages, respectively. However, none of the models were simulating satisfactorily the entire sediment graphs. [ABSTRACT FROM AUTHOR]

The duration and extent of sediment routing systems are intrinsically linked to crustal‐ to mantle‐scale processes. Therefore, distinct changes in the geodynamic regime may be captured in the detrital record. This study attempts to reconstruct the sediment routing system of the Canning Basin (Western Australia) during the Early Cretaceous to decipher its depositional response to Mesozoic‐Cenozoic supercontinent dispersal. Specifically, we reconstruct source‐to‐sink relationships for the Broome Sandstone (Dampier Peninsula) and proximal modern sediments through multi‐proxy analysis of detrital zircon (U–Pb, Lu–Hf and trace elements) and detrital rutile (U–Pb and trace elements). Multi‐proxy comparison of detrital signatures and potential sources reveals that the majority of the detrital zircon and rutile grains are ultimately sourced from crystalline basement in central Australia (Musgrave Province and Arunta region) and that proximal sediment supply (i.e., Kimberley region) is negligible. However, a significant proportion of detritus might be derived from intermediate sedimentary sources in central Australia (e.g., Amadeus Basin) rather than directly from erosion of crystalline basement. Broome Sandstone data are consistent with a large‐scale drainage system with headwaters in central Australia. Contextualization with other broadly coeval drainage systems suggests that central Australia acted as a major drainage divide during the Early Cretaceous. Importantly, reorganization after supercontinent dispersal is characterized by the continuation of a sediment pathway remnant of an earlier transcontinental routing system originating in Antarctica that provided a template for Early Cretaceous drainage. Review of older Canning Basin strata implies a prolonged denudation history of central Australian lithologies. These observations are consistent with the long‐lived intracontinental tectonic activity of central Australia governing punctuated sediment generation and dispersion more broadly across Australia and emphasize the impact of deep Earth processes on sediment routing systems. [ABSTRACT FROM AUTHOR]

Seismic geomorphology and stratigraphic analysis can reveal how source-to-sink systems dynamically respond to climatic and tectonic forcing. This study uses seismic reflection data from the Norwegian Sea to investigate the stratigraphic response to a short-lived (0.2 Myr) period of climate change during the Paleocene-Eocene Thermal Maximum (PETM), superimposed on a long-lived (∼8 Myr) period of hinterland uplift. The data show that long-term uplift resulted in ∼300 m of relative sea-level fall, forced regression and formation of incised valleys during the latest Paleocene-earliest Eocene. The short-lived PETM climate perturbation at ∼56 Ma changed the transport dynamics of the system, allowing sediment to be bypassed to wide channel complexes on the basin floor, feeding a large mud-rich basin-floor fan more than 50 km into the basin. Our analysis also suggest that sediment supply was up to four times higher during the PETM compared to earlier and later periods. Maximum regression at ∼55.5 Ma resulted in the formation of a subaerial unconformity. The style of subaerial incision was dictated by shelf accommodation and proximity to the area of direct sediment input. Out-of-grade shelves and slopes sourced by littoral drift were prone to incision, but direct-fed and graded shelves and slopes were not. Despite maximum regression, sediments were not transported significantly beyond the toe-of-slope aprons, suggesting that rapid climate change was more efficient in bypassing sediment to the deep-water than low stands of sea level. As long-term accommodation increased after the PETM, deltas were still able to reach shelf edge, but periods of maximum regression were not associated with deep incisions along the outer shelf and only smaller canyons and gullies formed. The shelf-slope wedge was finally transgressed at ∼51 Ma. The age of deep valley incisions overlaps with the time of subaerial erosion in the East Shetland and Faroe-Shetland basins, suggesting a common mechanism for North Atlantic uplift around 55–56 Ma. Other seismic stratigraphic surfaces do not seem to be regionally time-equivalent, highlighting the importance of local controls on internal architecture of shelf-slope wedges. This study demonstrates the high-resolution stratigraphic response to long- and short-term external forcing together with intrinsic processes and can help identify similar relationships in other areas.

Interpreting the links between transient in‐channel fine sediment storage and the dynamics of suspended sediment transport during flood events helps the understanding of river geomorphology, and also the impacts of fine sediment on water quality and bed habitats of rivers and downstream receiving environments. We present a unique physically based model of suspended sediment transport which is intimately coupled with fine sediment deposition and re‐entrainment processes within the gravel bed. This multi‐size fraction theory provides unique information about the effect of fine sediment size classes due to their dynamics and associated river bed changes in net deposition. The data from a series of flood events from the Oreti River, located in Southland, New Zealand were used to test the ability of this theory to provide a description of the dynamics of the fine sediment size distribution, their concentration, load, and rate of river bed deposition and re‐entrainment. After calibration of the model using the data from one flood event, the model provides good agreement between observed and modeled fine sediment concentration and event load for seven subsequent test events. One of the main applications of this theory in future is for routing suspended sediment concentration and changes on fine sediment deposition down a river network. Plain Language Summary: This study introduce a new theory for determining suspended sediment transport and deposition and re‐entrainment of deposited fine sediments in gravel bed rivers. We tested the theory using data from the Oreti River and found good agreements between observed and predicted suspended sediment concentration during flood events and suspended sediment load. Key Points: A new physically based theory of suspended sediment transport with sediment deposition and re‐entrainment rates is presentedThe theory provides user‐defined size fraction classes integrating at each time step to determine total fine sediment transportThe optimization of parameters obtained using the calibration event provide accurate prediction of sediment dynamics for seven test events [ABSTRACT FROM AUTHOR]

The reliable estimate of the sediment load and streamflow is essential for water resources and flood management. In this study, the entropy-based technique and HEC-RAS are used for flow routing followed by sediment routing in HEC-RAS. The paper's novelty is its application to data-deficit river networks, where observed sediment load and flow on tributaries are absent. The proposed method accommodates the flow and sediment contribution from the tributaries to the downstream station on a reach, despite unavailable observed data on it. The adopted flow routing techniques are applied to predict downstream flow on three different reaches (on the Mahanadi and the Godavari River). The prediction accuracy is evaluated using three statistical indices ‒ Nash–Sutcliffe efficiency (NSE), relative error (RE), and Coefficient of determination (R2). Both flow routing techniques showed good performance for all three reaches (with or without tributaries), having NSE, R2 > 0.8, and RE < 13%. Despite the comparable performance, the entropy-based routing is suggested for natural rivers with or without tributary as it avoids the iterative calibration process to determine the roughness coefficient. Further, the sediment routing is performed on the data-deficit reach of the Mahanadi River to obtain the best-suited sediment transport function. The simulated sediment load using the Yang transport function matched satisfactorily with the observed data with NSE, R2 > 0.85, and RE < –27%. Subsequently, the Yang transport function and entropy-based flow routing are utilized for the sediment and flow estimation at an ungauged station on the Mahanadi river. [ABSTRACT FROM AUTHOR]

Upper Triassic to lowest Upper Jurassic strata in north‐eastern Mexico record surface processes during the early rifting that led to the opening of the Gulf of Mexico. Exposed near Ciudad Victoria, Tamaulipas and northwest to Galeana, Nuevo Leon, these continental deposits are called the Huizachal Group. Several key questions about these strata hamper their integration into a regional understanding of Late Triassic and Jurassic sediment routing and deposition. First, the depositional age of the stratigraphically lowest unit, the El Alamar Formation, is less well established than the depositional ages of the stratigraphically higher parts of the succession, leading to questions about the timinig of the onset of tectonic context, and regional correlation of these strata. Second, better knowledge of provenance and sediment routing, including fluvial transport distance, can help determine whether and when the depositional basin was split into subbasins versus connected by a throughgoing river system. This study uses sandstone detrital zircon U‐Pb isotopic ages and clast compositions to constrain depositional ages and reconstruct tectonic setting and provenance. Detrital zircon U‐Pb ages yielded a maximum depositional age of 210 Ma for the part of the El Alamar Formation exposed near Galeana, younger than previously determined. Although long‐distance (>100 km) sediment transport cannot be ruled out, the sources for Huizachal Group sandstone framework grains and detrital zircon could have been entirely local, within about 100 km. Alluvial deposits and pyroclastic and lava flows likewise indicate transport of no more than 100 km. We therefore infer deposition in partitioned rift basins receiving sediment from local sources. These data and interpretations contribute to understanding surface processes during the initial rifting that eventually led to opening of the Gulf of Mexico. [ABSTRACT FROM AUTHOR]

An important gap in the management of land erosion in mining‐affected areas is the understanding of the entire sediment routing system and the links between sources and storage at the catchment scale. In this study, we examine sediment delivery and its seasonality in the nickel mining‐affected Santa Cruz and Pamalabawan catchments in the Philippines. We monitored discharge, suspended sediment concentrations and suspended sediment loads across 13 sub‐catchments with contrasting degrees of mining influence from June 2018 to July 2019. First, we show the importance of the size of the area that has been physically disturbed within our sub‐catchments, with as little as 10–22% of relative disturbance area being enough to generate four‐fold to eight‐fold increase in the sediment yield relative to less disturbed and pristine areas. We found that sub‐catchments with > 10% disturbance exhibit the highest sediment yields (15.5 ± 44.7 t km−2 d−1) compared with sub‐catchments with < 10% disturbance (3.6 ± 17.7 t km−2 d−1) and undisturbed catchments (2.0 ± 5.7 t km−2 d−1). We also show that sediment flushing predominantly occurs in the most disturbed sub‐catchments at the onset of the wet season. A small number of flood events transports the bulk of the sediment, with hysteresis effects being most pronounced in disturbed areas. Lastly, we show that floodplain sediment recycling exerts a key control on sediment delivery at both reach and catchment scales, with the relative contribution of floodplain sources to the sediment budget becoming dominant in the latter stages of the wet season‐ up to 89% of the total sediment export per storm event. This study highlights the importance of both degree of disturbance and sediment pathways in controlling sediment transport in mining‐disturbed areas, and that considering the entire sediment routing system including intermediate stores is crucial to optimizing existing and future measures against siltation and potential contamination of trace metals and metalloids downstream of mining areas. [ABSTRACT FROM AUTHOR]

Sea level is thought to be the primary driver of alternating deposition of carbonate and siliciclastic sediment in shelf settings, with carbonates dominating during transgressive/highstands and siliciclastics during lowstands. Although sediment supply is critically important for shelf‐margin growth in siliciclastic systems, few studies demonstrate its impact on mixed carbonate‐siliciclastic systems. The Permian Basin in Texas, United States, provides an opportunity to investigate the basin evolution regarding the source, sediment routing and particularly shelf/slope growth from syn‐ to postorogenic phases during alternating carbonate and siliciclastic sedimentation. Published detrital zircon data show that the proportion of orogen‐related sources decreased significantly from an earliest Permian synorogenic phase (ca. 298 Ma) to a Leonardian (ca. 280–271 Ma) postorogenic phase, in concert with a grain‐size change from fine‐ to medium‐grained sand to silt. Although along‐strike lateral variabilities exist on the shelf margin, the shelf‐margin evolution characteristics show a significant difference among the Northern Shelf, Eastern Shelf and Central Basin Platform. The synorogenic Eastern Shelf exhibits a significant higher progradation rate than does the postorogenic Northern Shelf. The progradation and aggradation ratio of siliciclastic‐rich intervals in the Eastern Shelf is significantly higher than those of carbonate‐rich intervals in the Eastern Shelf and carbonate‐ or siliciclastic‐rich intervals in the Northern Shelf. In contrast, the Central Basin Platform, with no siliciclastic sediment supply, records almost no progradation regardless of orogenic phases. There is an increase in slope gradient with decreasing sediment supply during this second‐order sequence from the Permian Cisuralian Series to the end of the Guadalupian Series. This study demonstrates that tectonically driven siliciclastic sediment supply was the main mechanism controlling the shelf and slope evolution in alternating siliciclastic and carbonate deposition. [ABSTRACT FROM AUTHOR]

Whilst time‐series of sediment transport in gullies in both laboratory experimental and field settings can be determined through instrumentation, quantifying the spatial distribution of transport rates remains challenging. The morphological method, which was proposed for estimating bed‐material transport in both one‐ and two‐dimensions in rivers, provides an alternative. Here, we developed this method for gully systems. A laboratory catchment was used to simulate gully erosion. High‐resolution topographical data were acquired by close‐range digital photogrammetry. Morphological changes were determined using high‐resolution topographic data and an associated level of detection. Based on measured morphological changes, one‐dimensional (1D) and two‐dimensional (2D) sediment transport rates were calculated via cross‐section by cross‐section routing (1D) and cell by cell routing (2D). The 1D application provided a general trend of longitudinal variation of sediment transport for the whole gully system, increased gradually from zones of headward extension to a zone downstream where erosion and deposition were in balance, and sediment transport rates less variable in space. For the 2D application, hydrological and blended hydrological‐hydraulic routing solutions were compared. We found that the level of negative transport was insensitive to whether or not a blended hydrological‐hydraulic routing was used and that results from applying the hydrological routing throughout were not significantly degraded. We also found that consideration should be given to spatial and temporal resolution of the topographic data. The 2D application provided spatial patterns of sediment transport that vary with gully evolution. The main gully remained a high transport corridor but branch transport became more important through time. The framework we report provides an additional tool for both experimental and field quantification of the spatial patterns of sediment transport in gullies; and quantification of how these patterns change under different forcing factors. [ABSTRACT FROM AUTHOR]

Purpose: A novel concept of suspended sediment (SS) routing through a small reservoir is proposed that relies on the particle properties in the reservoir inflow. Methods: The SS routing through the reservoir is described following the single continuous stirred tank reactor concept with only one model parameter, the SS decay coefficient. This parameter is linked to the sediment settling velocity and water flow velocity. Hence, the model does not require a direct calibration with recorded data. This model was tested on a small reservoir in Warsaw, Poland, with seven storm events. Suspended sediment samples at the reservoir inflow and outflow were taken manually during the passage of flood flows at irregular intervals. The performance of the proposed method was verified with the approach when the model parameter is estimated directly from recorded events. Results: The parameter calculated based on particle properties was about 10 times higher than the corresponding parameter optimized from recorded SS events. Hence, there was a need to introduce a correction factor to accurately predict the effluent SS. This led to a high model performance for all events (Nash-Sutcliffe = 0.672 on average). Conclusions: (i) The proposed SS routing model based on particle properties has been proven to accurately simulate SS in the reservoir outlet. (ii) Thus, the parameter can be estimated from the sediment settling velocity and water flow velocity, but the correction factor must be applied. (iii) Our findings acknowledge difficulties in describing SS routing through small reservoirs and indicate a lack of knowledge on the functioning of these reservoirs. [ABSTRACT FROM AUTHOR]

Deep‐water syn‐rift systems develop in partially‐ or transiently‐linked depocentres to form complicated depositional architectures, which are characterised by short transport distances, coarse grain sizes and a wide range of sedimentary processes. Exhumed systems that can help to constrain the tectono‐stratigraphic evolution of such systems are rare or complicated by inversion tectonics. Here, we document a mid‐Pleistocene deep‐water syn‐rift system fed by Gilbert‐type fan deltas in the hangingwall of a rift margin fault bounding the West Xylokastro Horst block, on the southern margin of the Gulf of Corinth, Greece. Structural and stratigraphic mapping combined with digital outcrop models permit observations along this syn‐rift depositional system from hinterland source to deep‐water sink. The West Xylokastro Fault hangingwall is filled by two distinct sediment systems; an axial system fed by coarse‐grained sediment gravity flows derived from fault‐tip Gilbert‐type fan deltas and a lateral system dominated by mass transport deposits fed from an evolving fault‐scarp apron. Abrupt changes in stratigraphic architecture across the axial system are interpreted to record changes in relative base level, sediment supply and tectonics. Locally, depositional topography and intra‐basinal structures controlled sediment dispersal patterns, from bed‐scale infilling of local rugose topography above mass transport complexes, to basin‐scale confinement from the fault scarp apron. These acted to generate a temporally and spatially variable, heterogeneous stratigraphic architecture throughout the basin‐fill. The transition of the locus of sedimentation from a rift margin to a fault terrace through the syn‐sedimentary growth of a basinward fault produced regressive surfaces updip, which manifest themselves as channels in the deep‐water realm and acted to prograde the system. We present a new conceptual model that recognises coeval axial and transverse systems based on the stratigraphic architecture around the West Xylokastro fault block that emphasizes the lateral and vertical heterogeneity of rift basin‐fills with multiple entry points. [ABSTRACT FROM AUTHOR]

Subsurface deformation is a driver for river path selection when deformation rates become comparable to the autogenic mobility rate of rivers. Here we combine geomorphology, soil and sediment facies analyses, and geophysical data of the Late Quaternary sediments of the central Garo‐Rajmahal Gap in Northwest Bengal to link subsurface deformation with surface processes. We show variable sedimentation characteristics, from slow rates (<0.8 mm/year) in the Tista megafan at the foot of the Himalaya to nondeposition at the exposed surface of the Barind Tract to the south, enabling the development of mature soils. Combined subsidence in the Tista fan and uplift of the Barind Tract are consistent with a N‐S flexural response of the Indian plate to loading of the Himalaya Mountains given a low value of elastic thickness (15–25 km). Provenance analysis based on bulk strontium concentration suggests a dispersal of sediment consistent with this flexural deformation—in particular the abandonment of the Barind Tract by a Pleistocene Brahmaputra River and the current extents of the Tista megafan lobes. Overall, these results highlight the control by deeply rooted deformation patterns on the routing of sediment by large rivers in foreland settings. [ABSTRACT FROM AUTHOR]

Understanding the development of sedimentary systems during continental rifting is important for tracking environmental change and lithospheric processes. Conceptual models have been developed for the sourcing, routing and facies architecture of sediments in rift‐settings, driven in part by quantitative sediment tracking. Here, we present laser ablation split‐stream detrital zircon U/Pb geochronology and Hf‐isotopes for post‐rift (Cretaceous‐Paleogene) clastic sediments from Ocean Drilling Program (ODP) wells and Plio‐Pleistocene palaeoshoreline material, from the southern margin of Australia. Provenance results are contextualized through comparison with well‐characterized source regions and regional pre‐ and syn‐rift sediment reservoirs to track changes associated with Australia‐Antarctica separation during East Gondwana break‐up. The provenance character of the post‐rift sediments studied are distinct from pre‐existing sediment reservoirs and demonstrate termination of previously stable sediment routing systems and a dominance of local basement of the Proterozoic Madura and Coompana provinces (~1.2 Ga and CHUR‐like Hf‐signatures; Moodini Supersuite) in offshore ODP wells. A composite post‐rift Cretaceous?‐Eocene sample in the easternmost well expresses characteristic Phanerozoic zircon age signatures associated with source regions in eastern Australia that are interpreted to reflect inversion in the Ceduna Sub‐basin to the east. Detrital zircon signatures in Plio‐Pleistocene palaeoshoreline sediment are also relatively distinct, indicating derivation from coastal erosion in the Leeuwin Complex (~0.5 and 0.7 Ga subchondritic grains) and Albany–Fraser Orogen (~1.2 Ga subchondritic grains) several hundred, to over a thousand kilometers to the west. Collectively, results highlight the fundamental geological processes associated with rifting that dramatically change the character of sediment provenance via (a) isolation of pre‐existing primary and secondary sources of detritus, (b) development of new source regions in basin compartmentalized highs and localized fault scarps, and (c) establishment of marine and coastal currents that redefine clastic sediment transport. [ABSTRACT FROM AUTHOR]

Quantifying the time scales of sediment transport and storage through river systems is fundamental for understanding weathering processes, biogeochemical cycling, and improving watershed management, but measuring sediment transit time is challenging. Here we provide the first systematic test of measuring cosmogenic meteoric Beryllium‐10 (10Bem) in the sediment load of a large alluvial river to quantify sediment transit times. We take advantage of a natural experiment in the Rio Bermejo, a lowland alluvial river traversing the east Andean foreland basin in northern Argentina. This river has no tributaries along its trunk channel for nearly 1,300 km downstream from the mountain front. We sampled suspended sediment depth profiles along the channel and measured the concentrations of 10Bem in the chemically extracted grain coatings. We calculated depth‐integrated 10Bem concentrations using sediment flux data and found that 10Bem concentrations increase 230% from upstream to downstream, indicating a mean total sediment transit time of 8.4 ± 2.2 kyr. Bulk sediment budget‐based estimates of channel belt and fan storage times suggest that the 10Bem tracer records mixing of old and young sediment reservoirs. On a reach scale, 10Bem transit times are shorter where the channel is braided and superelevated above the floodplain, and longer where the channel is incised and meandering, suggesting that transit time is controlled by channel morphodynamics. This is the first systematic application of 10Bem as a sediment transit time tracer and highlights the method's potential for inferring sediment routing and storage dynamics in large river systems. Plain Language Summary: Understanding how long sediment takes to travel downstream in rivers, also known as sediment "transit time," is crucial for responsible watershed management and constraining global biogeochemical cycles. We aim to measure transit times for large rivers and determine the processes regulating this time scale. We present a new transit time proxy based on beryllium‐10 (10Be), a rare isotope produced in the atmosphere and delivered to Earth by rain. If river sediment collected downstream has more 10Be than sediment upstream, this indicates that sediment was trapped in the floodplain for many years before continuing to travel downstream. We collected river sediment at multiple locations from upstream to downstream along a large, undammed river, the Rio Bermejo in Argentina. We found that 10Be increased 230% from upstream to downstream, translating to a transit time of ~8,500 years. This long time scale implies that sediment and carbon delivered to rivers have enough time to be weathered or oxidized to CO2 before they are buried in the ocean. We also show that transit time is controlled by the river's shape and lateral mobility, suggesting that human alteration of channel shape or sediment supply will reduce a river's ability to use its floodplain for natural flood and erosion control. Key Points: Meteoric 10Be measured in depth‐integrated river suspended sediment geochemically records mean fluvial sediment transit timeIn the Rio Bermejo (Argentina), 10Be concentrations increase 230% over ~1,300 km transit distance, yielding a mean total transit time of 8.4 ± 2.2 × 103 yrReach‐scale analysis of 10Be‐derived transit times shows that tectonics, channel migration rates, and incision depth are primary drivers [ABSTRACT FROM AUTHOR]

Alluvial fans at tributary junctions modulate sediment flux through river networks, by buffering the mainstem channel from disturbance in the tributaries. Buffering occurs through the storage (and release) of sediment in fans. Here, we use an extensive historic dataset to characterise the ways in which fan buffering can change as sediment supply varies. In New Zealand's East Coast region, sediment supply and fluvial transport are prolific by global standards. We reconstruct how tributary‐junction fans in this region have responded to sediment generated by deforestation and extreme storms. The dynamics of five fans along the Tapuaeroa River are examined for the period 1939–2015. In response to major sediment loading, fans aggraded by up to 12 m and prograded by up to 170 m. Net sediment accumulation ranged from near zero to 1.5×106 m3. Fan size, gradient, sediment storage and buffering were influenced by both upstream and downstream controls. Key upstream (tributary) influences were sediment supply and stream power; downstream (mainstem) influences included distal confinement and, importantly, the nature of fan interaction with the mainstem, which aggraded by up to 6 m. The fans' ability to buffer the Tapuaeroa River from change in the tributaries was largely governed by this downstream interaction: as the mainstem aggraded, it increasingly curtailed fan progradation, thus limiting buffering. Previous studies of tributary‐junction fans have related fan morphometry to basin characteristics. However, we find that fan slope and area can vary considerably at decadal, annual or even monthly timescales. Consequently, we suggest that such studies could benefit by examining regional histories of disturbance. © 2019 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Sediment routing systems may be exposed to different external controls that can modulate long and short-term sediment delivery to nearby basins. Here we investigate a Paleocene depositional system offshore western Norway that was subjected to long-term (∼10 Myr) tectonic perturbation and significant hinterland erosion. Superimposed on this long-term uplift, the system was also subjected to a short-lived climatic perturbation, which lasted ∼200 kyr. Regional 3D seismic reflection data is integrated with high resolution borehole and biostratigraphic data to map the stratigraphic responses to these different scales of perturbations on the Paleocene system. The initiation of the tectonic perturbation is marked by an angular unconformity in seismic data at the base of the Paleocene. An increase in sediment supply followed, causing progradation of a confined shelf-slope wedge during the Middle and Late Paleocene. The end of the tectonic perturbation is marked by onlap in the lowermost Eocene and a shift from a confined to a more lateral extensive depositional system. Calculations indicate that the tectonic uplift caused an order of magnitude increase in sediment supply to the basin. This period coincided with the Paleocene-Eocene Thermal Maximum (PETM), which is documented by biostratigraphic data as a discrete event within the overall regressive system. Although the PETM has been associated with increased continental runoff in the North Atlantic, no peak in sediment supply can be resolved in the available dataset. This study shows that the system response to tectonic perturbations may vary along strike, depending on the size of the routing systems and the antecedent topography prior to hinterland uplift. A low supply system may produce a tectonically linked shelf-slope wedge that is of similar thickness as a climatically linked wedge in a high supply system. This study documents how the same routing system responded to perturbations operating at different spatial and temporal scales and may help recognize similar process-response relationships in other areas.

The Andean Plateau of NW Argentina is a prominent example of a high‐elevation orogenic plateau characterized by internal drainage, arid to hyper‐arid climatic conditions and a compressional basin‐and‐range morphology comprising thick sedimentary basins. However, the development of the plateau as a geomorphic entity is not well understood. Enhanced orographic rainout along the eastern, windward plateau flank causes reduced fluvial run‐off and thus subdued surface‐process rates in the arid hinterland. Despite this, many Puna basins document a complex history of fluvial processes that have transformed the landscape from aggrading basins with coalescing alluvial fans to the formation of multiple fluvial terraces that are now abandoned. Here, we present data from the San Antonio de los Cobres (SAC) area, a sub‐catchment of the Salinas Grandes Basin located on the eastern Puna Plateau bordering the externally drained Eastern Cordillera. Our data include: (a) new radiometric U‐Pb zircon data from intercalated volcanic ash layers and detrital zircons from sedimentary key horizons; (b) sedimentary and geochemical provenance indicators; (c) river profile analysis; and (d) palaeo‐landscape reconstruction to assess aggradation, incision and basin connectivity. Our results suggest that the eastern Puna margin evolved from a structurally controlled intermontane basin during the Middle Miocene, similar to intermontane basins in the Mio‐Pliocene Eastern Cordillera and the broken Andean foreland. Our refined basin stratigraphy implies that sedimentation continued during the Late Mio‐Pliocene and the Quaternary, after which the SAC area was subjected to basin incision and excavation of the sedimentary fill. Because this incision is unrelated to baselevel changes and tectonic processes, and is similar in timing to the onset of basin fill and excavation cycles of intermontane basins in the adjacent Eastern Cordillera, we suspect a regional climatic driver, triggered by the Mid‐Pleistocene Climate Transition, caused the present‐day morphology. Our observations suggest that lateral orogenic growth, aridification of orogenic interiors, and protracted plateau sedimentation are all part of a complex process chain necessary to establish and maintain geomorphic characteristics of orogenic plateaus in tectonically active mountain belts. [ABSTRACT FROM AUTHOR]

Abstract In the Gulf of Lions (Western Mediterranean), the emplacement of a large (160 km3) mass transport deposit, the Rhone Western Mass Transport Deposit (RWMTD), at the base of slope, aside the Rhone deep-sea fan between 1800 and 2700 m water depth, resulted in a major modification of the sediment routing by clogging a drainage network and blocking at the base of slope sediments that were previously routed into the Valencia channel and the Balearic abyssal plain. The RWMTD was sourced from sediments of the western flank of the Rhone upper fan and the adjacent base of slope. The mass transport deposit is characterized by a transparent seismic facies and sediment cores show that it is composed of a stiff laminated muddy lithofacies characteristic of the Rhone fan turbidites with marked contorted beds indicative of remoulding. AMS radiocarbon dating shows that the RWMTD was emplaced between 19.9 and 21.5 ka cal BP. It is coeval, within dating uncertainties, with the emplacement of a megaturbidite in the Balearic Abyssal Plain and immediately predates a major avulsion of the Rhone turbidite channel that led to the emplacement of an avulsion lobe (the neofan) on top of the RWMTD. It is not possible to affirm a genetic link between these three major gravity events but one can argue that they share a common forcing in relation with massive turbiditic accumulation during the last sea-level lowstand at the end of the Last Glacial Maximum. This study outlines the importance of mass transport deposits in the building of turbidite systems and, more generally, the major control of mass wasting on the routing and dispersal of sediments across continental margins. Highlights • Several mass wasting events occurred maybe simultaneously in the Gulf of Lions at the end of the last glacial maximum lowstand, between 19.5 and 21.7 ka cal BP. • Submarine Mass Transport Deposits can radically modify sediment routing pathways on the continental slope and rise. • Large Mass Transport Deposits (160 km3) can be obscured on the seabed where sedimentation rate is high. [ABSTRACT FROM AUTHOR]

Regional climate is an important control on the rate of coarse sediment mobilization and transport in alpine river systems. Changes in climate are then expected to cause a cascade of geomorphic responses, including adjustments in downstream channel morphology. However, the mechanics and sensitivity of channel response to short‐term climate variability remain poorly documented. In the Nooksack River, which drains a glaciated stratovolcano in Washington State, bed elevation changes were inferred from shifting stage‐discharge relations at seven U.S Geological Survey stream gages. Decadal‐scale elevation trends can be explained as a downstream‐propagating channel response to regional climate variability, where periods of persistent warm, dry (cool and wet) conditions corresponded to periods of aggradation (incision). The channel elevation response propagated downstream at a rate of 1 to 4 km per year; propagation rate scaled closely with channel slope. Historical trends in glacier extent and flood intensity both show some potential to explain climate‐sediment linkages, though assessing causation is complicated by the shared climate signal in both records. Results show the influence of the Pacific Decadal Oscillation, with relatively high coarse sediment yields prior to 1950 and since 1980, and notably lower sediment yields from 1950 to 1980. Measured sediment yields from nearby glaciated basins corroborate this history, suggesting a regional consistency to these climate‐sediment linkages. These results document consistent relations between climate, sediment supply, and downstream channel response at the basin scale, with channel responses propagating downstream over periods of decades with little apparent attenuation. Plain Language Summary: The shape and form of a gravel‐bedded river is a function of the amount of water and sediment supplied from upstream. Climate‐driven changes in the amount of sediment supplied from higher‐elevation source areas may then cause changes in downstream channel form, resulting in changes in habitat suitability or flood conveyance. However, the linkages between climate, sediment production, and downstream channel response are complicated and often difficult to monitor, leaving it unclear if or how rivers might respond to climate variability over societally important timescales of years to decades. In the glaciated Nooksack River in Washington State, we observe that changes in climate over the past century have resulted in distinct and consistent changes in channel bed elevation. Those changes appear first in the headwaters and then propagate downstream over a period of decades. Channel change in the upper river is then a response to climate about 20 years prior, while channel change in the lower river is a response to climate about 70 years ago. These results provide evidence that, at least in certain settings, short‐term climate signals influence downstream river systems and help define the timing and magnitude of those adjustments. Key Points: Geomorphic analysis of stream gage data in a glaciated river basin indicates a downstream‐propagating vertical channel response to climate variabilityThe climate‐driven bed elevation response propagated downstream at 1 to 4 km per year; propagation rate scaled closely with channel slopeComparisons with previously collected records suggest a regionally coherent relation between climate variability and coarse sediment yield in sediment‐rich, glaciated basins [ABSTRACT FROM AUTHOR]

Abstract: The control of slide blocks on slope depositional systems is investigated in a high‐quality 3D seismic volume from the Espírito Santo Basin, SE Brazil. Seismic interpretation and statistical methods were used to understand the effect of differential compaction on strata proximal to the headwall of a blocky mass‐transport deposit (MTD), where blocks are large and undisturbed (remnant), and in the distal part of this same deposit. The distal part contains smaller rafted blocks that moved and deformed with the MTD. Upon their emplacement, the positive topographic relief of blocks created a rugged seafloor, confining sediment pathways and creating accommodation space for slope sediment. In parallel, competent blocks resisted compaction more than the surrounding debrite matrix during early burial. This resulted in differential compaction between competent blocks and soft flanking strata, in a process that was able to maintain a rugged seafloor for >5 Ma after burial. Around the largest blocks, a cluster of striations associated with a submarine channel bypassed these obstructions on the slope and, as a result, reflects important deflection by blocks and compaction‐related folds that were obstructing turbidite flows. Log‐log graphs were made to compare the width and height of different stratigraphic elements; blocks, depocentres and channels. There is a strong correlation between the sizes of each element, but with each subsequent stage (block–depocentre–channel) displaying marked reductions in height. Blocky MTDs found on passive margins across the globe are likely to experience similar effects during early burial to those documented in this work. [ABSTRACT FROM AUTHOR]

The Waiapu River catchment (drainage area of 1734-km 2 ) is one of the most prolific conveyors of sediment in the world, annually delivering roughly 35 Mt of fine material to the ocean from eroding gullies, hillslopes, and reworked sediment on valley floors. Tectonic and geologic influences, in combination with a dynamic climate influenced by tropical cyclones and clearance of vegetation from steep hillslopes, predisposes this region to high rates of erosion. The bedload sediment regime of the river is strongly influenced by several exceptionally large gullies and gully complexes that produce a coarse-grained, poorly sorted sediment mixture. Rapid abrasion and breakdown leads to high rates of suspended sediment yield. A wave of bedload material, manifesting as elevated bed levels and significant widening of active alluvial fills, has been triggered by large inputs of hillslope material from a few key tributary catchments following Cyclone Bola in 1988. We review the evidence for the relaxation process of the sedimentary system in the subsequent 29 years, appraising some of the legacy effects that may endure, as associated with reworking of the considerable alluvial stores within the Waiapu system. We use Structure-from-Motion (SfM) techniques and archival aerial photos to quantify changes in sediment storage at the base of two major gully systems in recent decades. A record of over 850 cross section surveys at 62 sites on 10 rivers throughout the catchment (1958–2017) indicates recent transition from a trend of continuous accumulation to downcutting and remobilisation of valley-bottom deposits. The channel cross sections provide a minimum estimate of sediment flux from source areas to the lower reaches of the river, giving a rudimentary but spatially extensive picture of the wave of material cascading through the drainage network. The largest impacts occur in the upper steepland rivers, closest to the landslide-derived sediment supply. Transport rates here, as inferred from cross section change, are at a maximum during an aggradational phase following Cyclone Bola then taper off, despite the large sediment accumulations remaining in the system. As of 2017, the river is in the process of incising the upper extents of this deposit on a trajectory of recovery toward pre-Bola conditions. The compilation of cross section data provides us with new insights into the sensitivity of particular sites in the landscape, as well as the changing relationship between reach sediment storage and transport rates during the response and relaxation phase of a major disturbance in a large catchment. [ABSTRACT FROM AUTHOR]

The purpose of the paper is to test forecasting of the sediment transport process, taking into account two main uncertainties involved in sediment transport modeling. These are: the lack of knowledge regarding future flows, and the uncertainty with respect to which sediment transport formula should be chosen for simulations. The river reach chosen for study is the outlet part of the Ner River, located in the central part of Poland. The main characteristic of the river is the presence of an intensive morphodynamic process, increasing flooding frequency. The approach proposed here is based on simulations with a sediment-routing model and assessment of the hydraulic condition changes on the basis of hydrodynamic calculations for the chosen characteristic flows. The data used include Digital Terrain Models (DTMs), cross-section measurements, and hydrological observations from the Dabie gauge station. The sediment and hydrodynamic calculations are performed using program HEC-RAS 5.0. Twenty inflow scenarios are of a 10-year duration and are composed on the basis of historical data. Meyer-Peter and Müller and Engelund-Hansen formulae are applied for the calculation of sediment transport intensity. The methodology presented here seems to be a good tool for the prediction of long-term impacts on water surface profiles caused by sediment deposition and erosion. [ABSTRACT FROM AUTHOR]

If sediments in a basin share a similar genetic history (derived from a common place, from a common suite of raw materials, under a common set of environmental conditions, and subsequently experienced a common burial and thermal history), then physical characteristics of those sediments should be internally consistent and inferences about one physical property in one part of the basin can be drawn reliably from other physical properties in other parts of the basin. Balanced mass between a prospective source and an observed sink can indicate shared genetic history. If the sediments in the sink don't balance with the source, then additional history must be accounted: perhaps other sources, or perhaps leaks. Balance can only be evaluated with deliberate analysis that precisely defines and accurately measures the relevant physical boundaries and conditions of the sink and the potential sources. The analysis must start with the sink and work backward to potential sources. An example from sediments of the last 190 Ma on the Angoche margin of Mozambique demonstrates that the immediately adjacent hinterland of a basin may not supply all the sediment, so that exotic sources must be considered. An example from sediments of the last 190 ka in the Corsican Trough illustrates the requirements for strict sedimentary accounting, including precise definition of the sediment body in 3 spatial and 1 temporal dimension; segmentation and characterization of the body according to physical characteristics and data quality; identification of sediment entry points; association of sediment sources with sediment entry points; segmentation and characterization of sources according to geology, environment, and volume and character of expected sediment. Constraining the range of possible explanations, and quantifying uncertainty around relevant parameters of both sink and source(s) provides valuable insight into the genetic history of sedimentary systems, even if the mass does not balance precisely. • Sediment-property predictions, including porosity, are more likely to succeed if the origin of the sediment is known. • ·The Angoche Margin contains more sediment than is produced by the adjacent hinterland and delivered by local rivers. • The Golo River and the Golo Canyons are less than half of the Corsica Trough source to sink sediment system. • A rigorous accounting for sediment source to sink mass balance must incorporate a comprehensive set of genetic factors.. • Uncertainties in mass-balance input factors are handled through Monte Carlo analysis. [ABSTRACT FROM AUTHOR]

[Display omitted] • Zircon Hf-isotopes and grain shape measured from Eucla Basin heavy mineral placers. • Detrital zircon Mesoproterozoic age and juvenile Hf-isotope signal is non-unique. • Distinct grain shape characteristics statistically defined for crystalline basement. • Triple characterization (U-Pb, Hf-isotope and grain shape) resolves provenance. • Underlying basement (via intermediate basins) identified as primary sediment source. Sediment provenance studies commonly utilize isotopic signatures to resolve detrital mineral sources and routing. However, non-unique ages and geochemical characteristics across geographically distinct crystalline source regions can lead to significant ambiguities in mineral provenance interpretations. Such ambiguity is apparent in southern Australia's Cenozoic Eucla Basin, which hosts world-class heavy mineral sand resources. Here, new Hf isotope data are provided from four heavy mineral prospects (N = 8, n = 844 [ N = samples, n = grains]). Zircon grain shape data are also presented for a suite of detrital Eucla Basin samples (N = 22, n = 35,604) and the basin's underlying basement, the Coompana Province (N = 13, n = 824). The data are integrated with published detrital and non-detrital primary zircon data to investigate the efficacy of grain shape analysis to better resolve the basin's mineral provenance. Zircon Hf isotope compositions indicate a primary Mesoproterozoic juvenile source for zircon melts (∼1250–1000 Ma, −2.5 < ɛ Hf > ∼+5) with additional contributions from a range of juvenile to evolved late Archean to Phanerozoic-aged zircon bearing magmas (−28.0 < ɛ Hf > +11). U–Pb geochronology and Hf isotopes are incapable of differentiating Mesoproterozoic-aged source rocks bounding the region for the majority of heavy mineral deposits analyzed as potential sources express overlapping crystallization ages and similarities in Hf-isotope characteristics. However, distinct zircon grain shapes (i.e., perimeter, major axis and circularity) facilitate improved differentiation across these Mesoproterozoic sources. Filtering of U–Pb age, Hf isotope and shape data implicate the underlying Madura and Coompana provinces as dominant sediment sources for Eucla Basin detritus aged ∼1400–1000 Ma. The lack of direct sediment pathways between the underlying basement provinces and placer sediments analyzed demonstrates the significance of zircon reworking from intermediate sedimentary basins in the formation of the economically significant Eucla Basin beach placers. Zircon grain shape represents a cheaply acquired and readily incorporated grain characteristic that can enhance provenance investigations. [ABSTRACT FROM AUTHOR]

An erosion and sediment transport component incorporated in the HYdrology Simulation using Time-ARea method ( HYSTAR) upland watershed model provides grid-based prediction of erosion, transport and deposition of sediment in a dynamic, continuous, and fully distributed framework. The model represents the spatiotemporally varied flow in sediment transport simulation by coupling the time-area routing method and sediment transport capacity approach within a grid-based spatial data model. This avoids the common, and simplistic, approach of using the Universal Soil Loss Equation ( USLE) to estimate erosion rates with a delivery ratio to relate gross soil erosion to sediment yield of a watershed, while enabling us to simulate two-dimensional sediment transport processes without the complexity of numerical solution of the partial differential governing equations. In using the time-area method for routing sediment, the model offers a novel alternative to watershed-scale sediment transport simulation that provides detailed spatial representation. In predicting four-year sediment hydrographs of a watershed in Virginia, the model provided good performance with R2 of 0.82 and 0.78 and relative error of −35% and 11% using the Yalin and Yang's sediment transport capacity equations, respectively. Prediction of spatiotemporal variation in sediment transport processes was evaluated using maps of sediment transport rates, concentrations, and erosion and deposition mass, which compare well with expected behavior of flow hydraulics and sediment transport processes. [ABSTRACT FROM AUTHOR]

A detailed petrological study has been performed for the end-Cretaceous clastic deposits of the southern Pyrenees. Provenance results indicate that the Maastrichtian systems from both the Àger and the Vallcebre synclines show compositional features that mainly consist of a high proportion of single and polycrystalline quartz grains, feldspar and plutonic fragments. By contrast, the sandstone systems of the Tremp syncline exhibit minor contributions from igneous source areas and higher amounts of carbonatic components. These results reveal that the Tremp basin had a source area interpreted as situated to the North in the uplifting Pyrenees. The fact that this basin does not show a high plutonic source signal indicates that the Àger and the Vallcebre basins had been fed from a distinct source area located to the South, here interpreted as the Ebro Massif. Thus, the differences mentioned above might imply that the Montsec High acted as a barrier, avoiding a southern influence in the Tremp basin. [ABSTRACT FROM AUTHOR]

In this study, the Morgan and Duzant version of the modified Morgan-Morgan-Finney (MMF) model coupled with geographical information system (GIS) is used for sediment yield estimation from the Gamber watershed, Satluj basin, Himachal Pradesh, India. The model incorporates particle size selectivity in the process of erosion, transport, and deposition, i.e., it simulates these processes for clay, silt, and sand separately. This modified MMF model also allows for surface runoff and sediment routing, which improves sediment yield estimation ac- curacy. It also determines the watershed contributions to the total sediment yield at the basin outlet. The present research fetches the MMF model in a geospatial environment and develops a system that can be used to estimate the actual sediment yield. Generally, it has been observed that the detachment of soil is greatly affected by raindrop impact. Therefore, the estimation of kinetic energy of erosive rainfall is a very important factor.Moreover, it has been noticed that the major contribution to kinetic energy of rainfall comes from direct throughfall, as compared to leaf drainage. Therefore, the relationship to estimate kinetic energy of direct throughfall developed for Indian conditions has been used rather than the traditional relationship developed for the United Kingdom. The model parameters were calibrated for the years 1998 and 2002. The results were validated for the years 1995 and 1999. The efficiency coefficient the model could achieve was 0.91. It was concluded that the model can estimate sediment yield from a catchment with reasonable accuracy. [ABSTRACT FROM AUTHOR]

Bedload transport and bedform mobility in large gravel-bed rivers are not easily monitored, especially during floods. Large reaches present difficulties in bed access during flows for flow measurements. Because of these logistical issues, the current knowledge about bedload transport processes and bedform mobility lacks field-based information, while this missing information would precisely match river management needs. The lack of information linking channel evolution and particle displacements is even more striking in wandering reaches. The Durance River is a large, wandering, gravel-bed river (catchment area: 14,280 km 2 ; mean width: 240 m), located in the southern French Alps and highly impacted by flow diversion and gravel mining. In order to improve current understanding of the link between sediment transport processes and river bed morphodynamics, we set up a sediment particle survey in the channel using Radio Frequency Identification (RFID) tracking and topographic surveys (GPS RTK and scour chains) for a 4-year recurrence interval flood. By combining topographic changes before and after a flood, intraflood erosion/deposition patterns from scour chains, differential routing of tracer particles, and spatial distribution of bed shear stress through a complex reach, this paper aims to define the critical shear stress for significant sediment mobility in this setting. Gravel tracking highlights displacement patterns in agreement with bar downstream migration and transport of particles across the riffle within this single flood event. Because no velocity measurements were possible during flood, a Telemac three-dimensional model helped interpret particle displacements by estimating spatial distribution of shear stresses and flow directions at peak flow. Although RFID tracking in a large, wandering, gravel-bed river does have some technical limitations (burial, recovery process time-consuming), it provides useful information on sediment routing through a riffle–pool sequence. [ABSTRACT FROM AUTHOR]

The relationship between tectonic uplift, climate change and continental silicate weathering has long been debated because deconstructing the tectonic and climatic impacts on continental silicate weathering is challenging. To address this issue, we present long-term climatic and silicate weathering records since 7.3 Ma on tectonically active NE Tibet retrieved from the SG-1 and SG-1b lake sediment drill cores in the western Qaidam Basin. We find distinct correlations between silicate weathering and regional climate on long-term (>106 years) and short-term (105–106 years) time scales. On long-term scales, silicate weathering intensity exhibits a consistent evolution with regional climate, both of which are dominantly controlled by global climate change. This evolution resulted in a stable weathering intensity during 7.3–~3.6 Ma and a weakening of weathering intensity since ~3.6 Ma, followed by a continuous decreasing trend after 2.6 Ma. However, on short-term scales, silicate weathering intensity displays out-of-phase changes with the regional climate at 6.9–3.7 Ma and 0.2–0.1 Ma and in-phase changes at 7.3–6.9 Ma and 3.7–0.2 Ma. We attribute this long-term consistency between the weathering intensity and climate to aridification in inland Asia, but the short-term inconsistencies at 6.9–3.7 Ma and 0.2–0.1 Ma to the change in the sediment routing system impacted by the regional climate within a tectonically active setting. Such a change in the sediment routing system along with sediment recycling may bias weathering indication on orbital time scales, and our study therefore suggests a more complex response of silicate weathering to tectonic and climatic forcings. [Display omitted] [ABSTRACT FROM AUTHOR]

Coring during Integrated Ocean Drilling Program Expeditions 315, 316, and 333 recovered turbiditic sands from the forearc Kumano Basin (Site C0002), a Quaternary slope basin (Site C0018), and uplifted trench wedge (Site C0006) along the Kumano Transect of the Nankai Trough accretionary wedge offshore of southwest Japan. The compositions of the submarine turbiditic sands here are investigated in terms of bulk and heavy mineral modal compositions to identify their provenance and dispersal mechanisms, as they may reflect changes in regional tectonics during the past ca. 1.5 Myrs. The results show a marked change in the detrital signature and heavy mineral composition in the forearc and slope basin facies around 1 Ma. This sudden change is interpreted to reflect a major change in the sand provenance, rather than heavy mineral dissolution and/or diagenetic effects, in response to changing tectonics and sedimentation patterns. In the trench-slope basin, the sands older than 1 Ma were probably eroded from the exposed Cretaceous-Tertiary accretionary complex of the Shimanto Belt and transported via the former course of the Tenryu submarine canyon system, which today enters the Nankai Trough northeast of the study area. In contrast, the high abundance of volcanic lithics and volcanic heavy mineral suites of the sands younger than 1 Ma points to a strong volcanic component of sediment derived from the Izu-Honshu collision zones and probably funnelled to this site through the Suruga Canyon. However, sands in the forearc basin show persistent presence of blue sodic amphiboles across the 1 Ma boundary, indicating continuous flux of sediments from the Kumano/Kinokawa River. This implies that the sands in the older turbidites were transported by transverse flow down the slope. The slope basin facies then switched to reflect longitudinal flow around 1 Ma, when the turbiditic sand tapped a volcanic provenance in the Izu-Honshu collision zone, while the sediments transported transversely became confined in the Kumano Basin. Therefore, the change in the depositional systems around 1 Ma is a manifestation of the decoupling of the sediment routing pattern from transverse to long-distance axial flow in response to forearc high uplift along the megasplay fault. [ABSTRACT FROM AUTHOR]

Watershed Best Management Practices (BMPs) are often designed to reduce loading from particle-borne contaminants, but the temporal lag between BMP implementation and improvement in receiving water quality is difficult to assess because particles are only moved downstream episodically, resting for long periods in storage between transport events. A theory is developed that describes the downstream movement of suspended sediment particles accounting for the time particles spend in storage given sediment budget data (by grain size fraction) and information on particle transit times through storage reservoirs. The theory is used to define a suspended sediment transport length scale that describes how far particles are carried during transport events, and to estimate a downstream particle velocity that includes time spent in storage. At 5 upland watersheds of the mid-Atlantic region, transport length scales for silt-clay range from 4 to 60 km, while those for sand range from 0.4 to 113 km. Mean sediment velocities for silt-clay range from 0.0072 km/yr to 0.12 km/yr, while those for sand range from 0.0008 km/yr to 0.20 km/yr, 4-6 orders of magnitude slower than the velocity of water in the channel. These results suggest lag times of 100-1000 years between BMP implementation and effectiveness in receiving waters such as the Chesapeake Bay (where BMPs are located upstream of the characteristic transport length scale). Many particles likely travel much faster than these average values, so further research is needed to determine the complete distribution of suspended sediment velocities in real watersheds. [ABSTRACT FROM AUTHOR]

• Late Miocene folding in deepwater NW Borneo influenced submarine channel development. • The Champion sediment-supply system comprised in its onshore part multiple rivers. • The paleo-Padas River was one of the primary rivers supplying lithic-rich sediment. • Variation in catchment-area geology influenced deepwater sediment composition. The northwest (NW) Borneo margin is one of the geologically most complex regions of Southeast Asia characterized by a steep slope gradient and an extensive deepwater fold and thrust belt. This area is economically important because of large-volume hydrocarbon accumulations in the deep-marine sandstones in fold and thrust anticlines. Although much attention has been paid to the distribution of deepwater reservoir rocks, the provenance of these rocks and compositional variations are yet not fully understood. In this study we present geomorphological and petrological analyses of Late Miocene deepwater channel deposits that form important reservoirs in the region. Our results reveal the presence of a northwest-trending deepwater channel system displaying morphological variations induced by syn -sedimentary structural development. Petrological analyses of core samples show a predominant lithic-rich rock composition in the reservoir sandstones, suggesting sediment supply from a lithic-rich Crocker Formation hinterland, probably through a paleo-Padas River. This rock composition differs from the quartz-rich rock composition of an adjacent contemporaneous deepwater reservoir mainly comprising reworked quartz-rich Meligan sandstones. The observed petrological differences are interpreted to reflect a Late Miocene multi-source sediment supply system that drained offshore different NW Borneo hinterland areas. Offshore, sediment transport to and across the slope was dominantly margin-perpendicular, linear or of low sinuosity, in the deepwater locally affected by faulting and folding. This study provides new insights into the complexity of sediment routing systems along continental margins, highlighting the influences of the configuration of the sediment supply system and tectonics on deepwater sedimentation. [ABSTRACT FROM AUTHOR]

Abstract: In the Late Neogene (Late Sarmatian s. l. — Dacian; 11 to 4Ma) the Carpathian Mountains to Dacian Basin was an enclosed source-to-sink system. The volume of sediment eroded from the Carpathians (estimated from previous semi-quantitative studies) closely matches the volume of sediment deposited in the Dacian Basin (about 100,000km3). The close values of the eroded and deposited sediment volume indicate the Carpathians as the main sediment source for Dacian Basin, with only limited input from adjacent areas. Based on depocenter thickness, grain size trend and paleocurrent data, two distinct areas in the Carpathian Mountains have been identified as the major sediment sources during this time interval. Each source area most likely delivered sediments to different depocenters within the Dacian Basin creating distinct sediment routing and sinks. Because of the similar sediment volumes sourced in Carpathians and deposited in Dacian Basin connectivity with adjacent basins did not significantly influence the sediment flux and routing of the Dacian Basin unless the sediment was bypassing the Dacian Basin. A probable sea-level drop of 50 to 100m during Pontian (time of the Messinian Salinity Crisis in the Mediterranean Basin) did not inflict important morphological changes to the Carpathians - Dacian Basin source-to-sink system. The system of the semi-enclosed Dacian Basin appears to have been autonomous, efficiently trapping incoming clastic material and apparently preventing significant spillage to the larger and deeper Black Sea Basin until Romanian time when it was filled and depositional environments changed from marine/lacustrine to fluvial. [Copyright &y& Elsevier]

Highlights: [•] Complex and simple concepts for sediment transport give very different results. [•] Complex not necessarily more reliable in data scarce areas. [•] Sediment transport calculations in data poor areas should be treated with care. [Copyright &y& Elsevier]

The northwest Argentine Andes constitute a premier natural laboratory to assess the complex interactions between isolated uplifts, orographic precipitation gradients, and related erosion and sedimentation patterns. Here we present new stratigraphic observations and age information from intermontane basin sediments to elucidate the Neogene to Quaternary shortening history and associated sediment dynamics of the broken Salta foreland. This part of the Andean orogen, which comprises an array of basement-cored range uplifts, is located at ∼25°S and lies to the east of the arid intraorogenic Altiplano/Puna plateau. In the Salta foreland, spatially and temporally disparate range uplift along steeply dipping inherited faults has resulted in foreland compartmentalization with steep basin-to-basin precipitation gradients. Sediment architecture and facies associations record a three-phase (∼10, ∼5, and <2 Ma), east directed, yet unsystematic evolution of shortening, foreland fragmentation, and ensuing changes in precipitation and sediment transport. The provenance signatures of these deposits reflect the trapping of sediments in the intermontane basins of the Andean hinterland, as well as the evolution of a severed fluvial network. Present-day moisture supply to the hinterland is determined by range relief and basin elevation. The conspiring effects of range uplift and low rainfall help the entrapment and long-term storage of sediments, ultimately raising basin elevation in the hinterland, which may amplify aridification in the orogen interior. [ABSTRACT FROM AUTHOR]

This paper presents a new numerical model for river morphological predictions. This tool predicts vertical and lateral cross-section variations for alluvial rivers, which is an important task in predicting the associated hazard zone after a flood event. The Model for the HYdraulics of SEdiments in Rivers, version 1.0 (MHYSER 1.0) is a semi-two-dimensional model using the stream tubes concept to achieve lateral variations of velocity, flow stresses, and sediment transport rates. Each stream tube has the same conveyance as the other ones. In MHYSER 1.0, the uncoupled approach is used to solve the set of conservation equations. After the backwater calculation, the river is divided into a finite number of stream tubes of equal conveyances. The sediment routing and bed adjustments calculations are accomplished separately along each stream tube taking into account lateral mass exchanges. The determination of depth and width adjustments is based on the minimum stream power theory. Moreover, MHYSER 1.0 offers two options to treat riverbank stability. The first one is based on the angle of repose. The bank slope should not be allowed to increase beyond a certain critical value supplied to MHYSER 1.0. The second one is based on the modified Bishop’s method to determine a safety factor evaluating the potential risk of a landslide along the river bank. [ABSTRACT FROM AUTHOR]

Constraining the controls on the distribution of sediment at a continental scale is a critical step in understanding long-term landscape and climate evolution. In particular, understanding of the role of rivers in wider sediment routing and impacts on aeolian loess formation on a continental scale remains limited. Extensive Quaternary loess deposits are present on the East European Plain and in the Black Sea - Caspian Sea region and are associated with major rivers draining numerous surrounding cratonic and orogenic hinterland areas. Coupled with this, complex changes in local and global sea level have affected the extent and drainage of the Caspian Sea and the Black Sea, and Quaternary glaciations have impinged on the northern margin of the East European Plain. This suggests that sediment routing and loess formation may show complex patterns and controls. Here, we apply U Pb dating of detrital zircons from fluvial, marine and aeolian (dominantly loess) sedimentary records on the East European Plain and in the Black Sea - Caspian Sea region. This shows a strong control of large rivers on the distribution of sediments at a continental scale in the region, through long-distance transport of several 1000 km, sourced from continental and mountain glacier areas prior to marine or atmospheric reworking and transportation. Strong spatial variability in zircon U Pb data from loess deposits on the East European Plain reveals multiple diverse sources to the different individual loess sections, whereas no significant temporal variability in loess source is detected during the Late Pleistocene of the Lower Volga loess in South Russia. While the sediment supply from glacial areas via rivers plays an important role for the provenance of East European Plain loess deposits, our data indicate that the stark spatial diversity in loess provenance on the East European Plain is often driven by the input of multiple local sources. Similar to the loess, marine sediments from different basins of the Black Sea and the Caspian Sea also show significant spatial variability. This variability is controlled by the bathymetry of the seas, leading to sedimentary intermixing by sea currents within, but not between different separated sea basins. A direct comparison of marine and aeolian sediments at the same depositional site suggests that although loess and marine sediments are both dominantly sourced from river sediments containing far travelled sedimentary material, local sources play a more important role in many loess deposits. • Rivers control sediment dynamics in the East European Plain. • Great spatial loess provenance variability in the Black Sea - Caspian Sea region. • Multiple diverse loess sources and multi-step pathways. [ABSTRACT FROM AUTHOR]

• α -dose of detrital zircon used to identify sedimentary lifecycle of grains. • Selective removal of more labile (metamict) zircon revealed by α -dose. • Source-normalized α -dose compares α -dose of detrital and source rock zircon grains. • Source-normalized α -dose discriminates first- versus multi-cycle grains. • Source-normalized α -dose is applicable to published U–Pb zircon data. Detrital zircon U–Pb ages are widely employed as an archive of geological processes through time. Changes in detrital zircon age patterns within sediments reflect changes in source areas that are often related to tectonic and/or climatic processes. However, discrimination of first-cycle and multi-cycle detrital zircon with primary crystalline and secondary sedimentary sources, respectively, can be challenging using only crystallisation age constraints. Here, we present U–Pb geochronology of detrital zircon from modern fluvial and littoral environments on the Scott Coastal Plain in Western Australia to investigate the use of α -dose to identify sedimentary recycling. The majority of 1032 concordant U–Pb ages are interpreted to be ultimately sourced from the local basement. However, U–Pb ages do not reflect the areal extent of source rocks and indicate significant reworking of coastal plain sediments. A novel metric – source-normalized α -dose – demonstrates predominant detrital zircon routing via recycling through intermediate storage. This metric is defined as the ratio of the average α -dose (a measure of metamictization) of detrital zircon belonging to a characteristic age group and the average α -dose of zircon grains within the corresponding source crystalline basement. Average values of source-normalized α -dose of detrital zircon populations <1 are interpreted to reflect selective removal of more labile (metamict) grains via attrition and diagenesis, indicating greater grain transport and recycling, whereas values of c. 1 signify shorter transport and a first-cycle origin. Application of this approach to ancient clastic systems is supported by consistency of results with independent indicators of progressive sedimentary recycling and/or transport. Source-normalized α -dose is an internal measure using zircon grain chemistry (U and Th), and avoids bias associated with multi-mineral measures of sediment recycling that may be related to source fertility. Additionally, source-normalized α -dose uses measures typically captured during routine U–Pb geochronology. Source-normalized α -dose of detrital zircon provides an additional method to address sedimentary source-to-sink transport and recycling, and ultimately allows more robust interpretation of U–Pb zircon data. [ABSTRACT FROM AUTHOR]

Effective management for wide-ranging species must be conducted over vast spatial extents, such as whole watersheds and regions. Managers and decision makers must often consider results of multiple quantitative and qualitative models in developing these large-scale multispecies management strategies. We present a scenario-based decision support system to evaluate watershed-scale management plans for multiple species of Pacific salmon in the Lewis River watershed in southwestern Washington, USA. We identified six aquatic restoration management strategies either described in the literature or in common use for watershed recovery planning. For each of the six strategies, actions were identified and their effect on the landscape was estimated. In this way, we created six potential future landscapes, each estimating how the watershed might look under one of the management strategies. We controlled for cost across the six modeled strategies by creating simple economic estimates of the cost of each restoration or protection action and fixing the total allowable cost under each strategy. We then applied a suite of evaluation models to estimate watershed function and habitat condition and to predict biological response to those habitat conditions. The concurrent use of many types of models and our spatially explicit approach enables analysis of the trade-offs among various types of habitat improvements and also among improvements in different areas within the watershed. We report predictions of the quantity, quality, and distribution of aquatic habitat as well as predictions for multiple species of species-specific habitat capacity and survival rates that might result from each of the six management strategies. We use our results to develop four on-the-ground watershed management strategies given alternative social constraints and manager profiles. Our approach provides technical guidance in the study watershed by predicting future impacts of potential strategies, guidance on strategy selection in other watersheds where such detailed analyses have not been completed, and a framework for organizing information and modeled predictions to best manage wide-ranging species. [ABSTRACT FROM AUTHOR]

Advance of part of the margin of the Greenland ice sheet across a proglacial moraine ridge between 1968 and 2002 caused progressive changes in moraine morphology, basal ice formation, debris release, ice-marginal sediment storage, and sediment transfer to the distal proglacial zone. When the ice margin is behind the moraine, most of the sediment released from the glacier is stored close to the ice margin. As the margin advances across the moraine the potential for ice-proximal sediment storage decreases and distal sediment flux is augmented by reactivation of moraine sediment. For six stages of advance associated with distinctive glacial and sedimentary processes we describe the ice margin, the debris-rich basal ice, debris release from the glacier, sediment routing into the proglacial zone, and geomorphic processes on the moraine. The overtopping of a moraine ridge is a significant glaciological, geomorphological and sedimentological threshold in glacier advance, likely to cause a distinctive pulse in distal sediment accumulation rates that should be taken into account when glacial sediments are interpreted to reconstruct glacier fluctuations. [ABSTRACT FROM AUTHOR]

Sediment storage in alluvial valleys can strongly modulate the downstream migration of sediment and associated contaminants through landscapes. Traditional methods for routing contaminated sediment through valleys focus on in-channel sediment transport but ignore the influence of sediment exchanges with temporary sediment storage reservoirs outside the channel, such as floodplains. In theory, probabilistic analysis of particle trajectories through valleys offers a useful strategy for quantifying the influence of sediment storage on the downstream movement of contaminated sediment. This paper describes a field application and test of this theory, using 137Cs as a sediment tracer over 45 years (1952-1997), downstream of a historical effluent outfall at the Los Alamos National Laboratory (LANL), New Mexico. The theory is parameterized using a sediment budget based on field data and an estimate of the 137Cs release history at the upstream boundary. The uncalibrated model reasonably replicates the approximate magnitude and spatial distribution of channel- and floodplain-stored 137Cs measured in an independent field study. Model runs quantify the role of sediment storage in the long-term migration of a pulse of contaminated sediment, quantify the downstream impact of upstream mitigation, and mathematically decompose the future 137Cs flux near the LANL property boundary to evaluate the relative contributions of various upstream contaminant sources. The fate of many sediment-bound contaminants is determined by the relative timescales of contaminant degradation and particle residence time in different types of sedimentary environments. The theory provides a viable approach for quantifying the long-term movement of contaminated sediment through valleys. [ABSTRACT FROM AUTHOR]

Excessive mangrove spreading causes a significant impact upon the ecosystem and flood control operations in the Guandu mangrove wetland (Guandu Natural Reserve), Taiwan. Aerial photos, taken between 1978 and 1994, reveal that marsh habitats, dominated by Cyperus malaccensis Lam. and Phragmites communis (L.) Trin., have changed into a swamp habitat, dominated by Kandelia candel (L.) Druce. The coverage area of K. candel has increased from 0.04ha in 1978 to 20.75ha in 1994. The Kandelia habitat was more salty and located at a higher ground surface elevation than was the P. communis habitat. Variations of the water surface elevation and reduction of the channel conveyance due to increase of the coverage area of K. candel (L.) Druce were also obtained in this study.A horizontal two-dimensional model, TABS-2, was applied in this study to simulate the hydraulic and sediment transport characteristics of this estuary wetland. Four cases with different removal ratios show that water surface elevation decreases as the removal ratio increases. When the removal ratio of Kandelia reaches 20%, variations of the water surface elevation in the wetland became insignificant. Significant sediment deposition occurs due to the extensive root network of Kandelia. The average deposition is about 33mm during a 200-year return period flood event. Removal of Kandelia reduces the sediment deposition rate. When the removal ratio reaches 20%, the reduction in sediment deposition is about 5mm. Considering the factors of flood protection and sediment deposition, the optimal removal ratio is between 10 and 20%. It also found that mangrove removal improves the ecological restoration of Uca (Thalassuca) Formosensis Rathbun, an endemic species of the fiddler crab in Taiwan. [Copyright &y& Elsevier]

Most calculations of bedload transport in rivers, including those in numerical models of aggradation and degradation, are 1-D: all hydraulic and transport-rate calculations are averaged over the channel width. Because bedload transport laws are nonlinear, width-averaged calculations will underestimate the true bedload flux if there is any local spatial variation in either the bed or the flow. This paper analyses the effects on bedload transport capacity of spatial variation in applied (τ) and critical (τc) shear stress, separately and in combination. A simple but versatile statistical model is used to represent variability in τ, with allowance for differences between sand- and gravel-bed rivers and for below-bankfull flow. Bedload flux is shown to increase greatly with the variance of τ, especially in gravel-bed rivers. Variability in τc through bed patchiness may increase, reduce, or make little difference to bedload flux depending on the correlation between τ and τc. Simple width averaging leads to severe underestimation of bedload transport in most conditions; some alternatives are considered. The findings have implications for sediment routing models (SRMs), but further research is needed to explore the issue fully. [Copyright &y& Elsevier]