Search

This study aims at estimating the rate of bed aggradation of the Jia Dhansiri River in Assam, India. It is carried out using two methods: (1) measurement of channel cross section in the field, and (2) measurement of variously dated maps for the period 1995–2006. Following these two methods, data on parameters pertaining to bed aggradation are generated and authenticated by comparison. Data on total bed aggradation during 1995–2006 are extrapolated from cross section graphs and again verified with a model proposed in this paper based on average water level of base year and current year and total bed aggradation. The rates of bed aggradations are 5.27 cm/y at Dhansiri Khuti village, 5.09 cm/y at Barigain village, 5.27 cm/y at Bagishakash village, and 2.64 cm/y at Thalthali village. No degradation zones are found in between during the study period except in minor magnitude and localized cases. If these rates of bed aggradation are continued and no significant changes in the channel morphology occur, then the river bed may merge with the low river bank after 11 years at Dhansiri Khuti village, 17 years at Barigaon village, 6 years at Bagishakash village, and 7 years at Thalthali village. The average channel aggradation during 11–years of period in the 16–km reach has estimated to be 3.65 cm/y. Again, if this rate is continued then the river bed will overtop low banks of the 16–km reach after 16 years. At this situation the river may attain a state of geomorphic threshold which may be channel shift following vulnerable slope(s).

A major programme of dam building is underway in many of the world's tropical countries. This raises the question of whether existing research is sufficient to fully understand the impacts of dams on tropical river systems. This paper provides a systematic review of what is known about the impacts of dams on river flows, sediment dynamics and geomorphic processes in tropical rivers. The review was conducted using the SCOPUS® and Web of Science® databases, with papers analysed to look for temporal and geographic patterns in published work, assess the approaches used to help understand dam impacts, and assess the nature and magnitude of impacts on the flow regimes and geomorphology (‘hydromorphology’) of tropical rivers. As part of the review, a meta-analysis was used to compare key impacts across different climate regions. Although research on tropical rivers remains scarce, existing work is sufficient to allow us to draw some very broad, general conclusions about the nature of hydromorphic change: tropical dams have resulted in reductions in flow variability, lower flood peaks, reductions in sediment supply and loads, and complex geomorphic adjustments that include both channel incision and aggradation at different times and downstream distances. At this general level, impacts are consistent with those observed in other climate regions. However, studies are too few and variable in their focus to determine whether some of the more specific aspects of change observed in tropical rivers (e.g. time to reach a new, adjusted state, and downstream recovery distance) differ consistently from those in other regions. The review helps stress the need for research that incorporates before-after comparisons of flow and geomorphic conditions, and for the wider application of tools available now for assessing hydromorphic change. Very few studies have considered hydromorphic processes when designing flow operational policies for tropical dams.

The Rio Grande fluvial system has evolved dramatically over the past 8 Ma, undergoing channel migrations, drainage capture and integration events, volcanic damming, and carving and refilling of paleocanyons. This paper is motivated by the need for a synthesis aimed at understanding processes driving regional drainage development, especially the roles of rifting, volcanism, and climate change. Major conclusions supported by our synthesis of published data are as follows: 1) 20–8 Ma southward drainage from the San Juan volcanic field into the deepening Rio Grande rift resulted in deposition of thick basin fill of the Santa Fe Group by rivers flowing on a south-sloping alluvial plain in the north and by alluvial fans within fault-segmented internally drained rift basins. 2) The ancestral Rio Chama river system developed by ~ 8 Ma to link northern New Mexico basins (Espanola and northern Albuquerque basins). 3) The ancestral Rio Grande joined the Rio Chama by 5 Ma and linked drainage from the San Juan Mountain headwaters to central New Mexico as an integrated axial river system. 4) The Rio Grande extended its reach progressively southward to central New Mexico (Palomas basin) by 4.5 Ma, to southern New Mexico (Mesilla basin) by 3.1 Ma, to Texas (Hueco basin) by 2.06 Ma, and joined the Pecos River to reach the Gulf of Mexico by ~ 800 ka. 5) The change from aggradation to bedrock incision to carve the Rio Grande valley took place after 1 Ma with differential incision rates of 10 to 150 m/Ma. Volcanism concurrent with the development of the river system provides a unique opportunity to apply multiple geochronometers to the study of its incision and drainage evolution. This paper reports seventeen new and 79 previously unpublished 40Ar/39Ar basalt ages in the context of a compilation of published geochronology. We also report detrital zircon ages for nineteen samples of ancestral Rio Grande-Rio Chama sediment, and compare them to eleven detrital K-feldspar samples to evaluate this potentially powerful new detrital grain analysis. The elongate geometry of 4.8 Ma basalt mesas in the Espanola basin suggests that the course of the Rio Grande connecting northern and central New Mexico drainage was established by ~ 5 Ma. Detrital zircon age spectra for ancestral Rio Grande alluvium underlying these basalt flows contain 10–12% of 37–27 Ma grains suggesting that the ~ 5 Ma Rio Grande was carrying detritus from, and likely had its headwaters in, the San Juan Mountains of southwestern Colorado. The 5 Ma to 3 Ma accumulation of an ~ 240-m-thick section of basalt flows on the Taos Plateau was accompanied by inset relationships downstream (Espanola basin), documenting the existence of a developing 5 to 2.5 Ma Rio Grande valley with an axial river. Coincident timing and inferred pre-volcanic knickpoints suggest that the construction of the Taos Plateau volcanic field in northern New Mexico helped drive downward integration to southern New Mexico by 4.5 Ma. Changes in ancestral Rio Grande sediment provenance from 2.6 Ma to 1.6 Ma document a northward shift of the Rio Grande-Rio Chama confluence and indicate that surface uplift of the Jemez Mountains diverted and reconfigured the river system, and likely drove further downstream integration. The Taos Plateau volcanic field reduced through-flowing surface drainage from the San Juan Mountains relative to the Sangre de Cristo Mountains until the ~ 440 ka spillover of Lake Alamosa in south-central Colorado, and we view this event as a re-integration, not initial integration, of upper Rio Grande drainage. Progressive downward integration of Rio Grande rift basins from 8 to 1 Ma was facilitated by a combination of processes: increased river gradients in the upper basin due to construction of volcanic fields and potential epeirogenic uplift; increased discharge due to climate change events; waning rift extension that allowed aggradation to exceed subsidence; dampening of topographic divides between basins by aggradation; probable groundwater connectivity; and lake spillover events. Downward integration events may crudely correlate to climate change “events” at 6 Ma (onset of the southwestern monsoon) and 2.6 Ma (global change toward glacial-interglacial climate). Magmatic influences included the building of the 6–2.5 Ma Taos Plateau volcanic field, construction of the 10 to 0 Ma Jemez Mountains, and 6 Ma to 0 Ma Jemez lineament volcanism that was likely associated with mantle-driven surface uplift in a northeast-trending zone across northern New Mexico. River damming events were driven by volcanism in the northern Rio Grande rift, while basin spillover/groundwater sapping events were punctuated by a combination of pluvial climates and continued headwater uplift in the southern Rocky Mountains. Integration of the Rio Grande system to the Gulf of Mexico by ~ 800 ka was facilitated by headwater uplift as well as the onset of ~ 100 ka high-amplitude glacial-interglacial cycles at ~ 900 ka that provided higher discharge and bedrock incision rates during the Pleistocene. We conclude that magmatic and tectonic forcing dominated over the last ~ 8 Ma, but were amplified by climate change events to determine the fluvial evolution of the Rio Grande system.

Northeast Alberta is the location of one of the world’s largest petroleum deposits, the Athabasca Oil Sands, hosted in Lower Cretaceous McMurray Formation sandstones. The McMurray Formation was deposited on a deeply eroded Upper Devonian unconformity surface that was strongly influenced by underlying carbonate and evaporite units. Development of the oil sands has resulted in a significant increase in new data related to the underlying Devonian of northeast Alberta. In particular, the requirement for deep disposal of water has resulted in a number of wells being drilled into and through the porous dolomites of the Middle Devonian Keg River Formation that is a few hundred metres below the McMurray bitumen deposits. In addition, the acquisition of large areas of high-resolution 3D seismic data to assist the delineation and development of the oil sands reserves has provided powerful insights into the depositional patterns and later dissolutive geometries of the underlying carbonate and evaporite deposits. The Keg River and overlying Prairie Evaporite formations that are the focus of this paper were deposited in the intracratonic Elk Point Basin that covered most of the area now delineated by the Western Canada Sedimentary Basin. These units and their lateral equivalents have been extensively studied in Saskatchewan, northwest Alberta, southern Northwest Territories and northeast British Columbia. In contrast, the two formations have been lightly studied and rarely published upon in northeast Alberta. The current detailed study of several areas with abundant new data, combined with a review of the regional dataset in northeast Alberta has provided new insights into the geology of these units. A revised stratigraphy for the two formations is presented which includes the formal definition of the proposed Aurora Member, a significant anhydrite unit within the Prairie Evaporite Formation that was previously included as a sub-unit of the Whitkow Member. The Keg River Formation is divided into the Lower and Upper Keg River members. The Lower Keg River Member is a thin, regionally consistent unit composed of an upward deepening transgressive systems tract. In most places, the Lower Keg River is overlain by the Upper Keg River Member which has two distinct facies. At the base is a widespread shallowing upwards microbial oncolitic facies, here referred to as the Keg River Ramp, which provided the foundation for more aerially restricted overlying deposits of shallow water carbonate. On the edge of the basin, a Basin Margin Platform formed and prograded out over the Keg River Ramp. In the centre of the basin, biogenic build-ups developed. Integrated interpretation of the seismic with the wells shows that the build-ups often have well established but aerially restricted reef margins of frame-building organisms. However, the bulk of these build-ups consist of loosely consolidated peloidal grainstones and packstones. A drop in sea level in conjunction with the development of a continuous barrier reef trend, the Presqu’ile Barrier, across the mouth of the Elk Point Basin caused restriction of the basin resulting in widespread laminites forming at the transitional contact between the Keg River and overlying Prairie Evaporite formations. As sea-level continued to drop, evaporitic drawdown converted the Elk Point Basin into a vast inland saline sea with an exposed marginal platform and emergent carbonate build-ups. The Prairie Evaporite Formation deposits of dolomite, anhydrite, gypsum, halite and potash were deposited in and around this sea. During this evaporitic phase almost all of the underlying Keg River limestone was converted to dolomite. The dolomitization resulted in the development of excellent porosity in most of the Keg River strata. The Prairie Evaporite is divided into two major brining upward cycles of deposition. The lower Prairie Evaporite cycle began with anhydrite and gypsum deposits forming adjacent to the exposed Keg River build-ups. These anhydrite units have been recognized and described in other parts of the Elk Point Basin but have never been formally defined stratigraphically. The paper provides detailed description and stratigraphic definition for this unit as the proposed Aurora Member. In the deeper parts of the basins between the reefs, evaporitic laminites accumulated. Eventually, the brines became supersaline and the remaining topography between the reefs was filled up with the Whitkow Member which consists mainly of halite. The upper Prairie Evaporite brining upward cycle began when a renewed rise in sea-level breached the Presqu’ile Barrier and allowed mesohaline brine to flood back across the basin. Continuing sea-level rise allowed reef growth to re-establish on top of the barrier which again led to restricted marine water flow into the basin. The vertical aggradation of the Presqu’ile Barrier as sea-level rose provided the accommodation space for the upper Prairie Evaporite cycle. The anhydrite portion of the cycle is represented by the widespread Shell Lake Member which transitions upward into the Leofnard Member which is composed predominantly of halite. In northeast Alberta, the Prairie Evaporite is capped by a thin clastic unit and the cycle of deposition is terminated by a significant unconformity at the base of the Watt Mountain Formation.

Numerical models have not yet systematically been used to predict properties of fluvial terrace records in order to guide fieldwork and sampling. This paper explores the potential of the longitudinal profile model FLUVER2 to predict testable field properties of the relatively well-studied, Late Quaternary Allier system in France. For the Allier terraces an overlapping 14C and U-series chronology as well as a record of 10Be erosion rates exist. The FLUVER2 modelling exercise is focused on the last 50 ka of the upper Allier reach because for this location and period the constraints of the available dating techniques are tightest. A systematic calibration based on terrace occurrence and thicknesses was done using three internal parameters related to (1) the sediment erodibility; (2) the sediment transport distance; and (3) the sediment supply derived from the surrounding landscape. As external model inputs, the best available, reconstructed, tectonic, climatic and base-level data were used. Calibrated model outputs demonstrate a plausible match with the existing fluvial record. Validation of model output was done by comparing the modelled and measured timing of aggradation and incision phases for the three locations. The modelled range of landscape erosion rates showed a reasonably good match with existing erosion rate estimates derived from 10Be measurements of fluvial sands. The quasi-validated model simulation was subsequently used to make new testable predictions about the timing and location of aggradation and erosion phases for three locations along the Allier river. The validated simulations predict that along the Allier, reach-specific dynamics of incision and aggradation, related to the variations in sediment supply by major tributaries, cause relevant differences in the local fluvial terrace stratigraphy. Numerical models have not yet systematically been used to predict properties of fluvial terrace records in order to guide fieldwork and sampling. This paper explores the potential of the longitudinal profile model FLUVER2 to predict testable field properties of the relatively well-studied, Late Quaternary Allier system in France. For the Allier terraces an overlapping 14 C and U-series chronology as well as a record of 10 Be erosion rates exist. The FLUVER2 modelling exercise is focused on the last 50 ka of the upper Allier reach because for this location and period the constraints of the available dating techniques are tightest. A systematic calibration based on terrace occurrence and thicknesses was done using three internal parameters related to (1) the sediment erodibility; (2) the sediment transport distance; and (3) the sediment supply derived from the surrounding landscape. As external model inputs, the best available, reconstructed, tectonic, climatic and base-level data were used. Calibrated model outputs demonstrate a plausible match with the existing fluvial record. Validation of model output was done by comparing the modelled and measured timing of aggradation and incision phases for the three locations. The modelled range of landscape erosion rates showed a reasonably good match with existing erosion rate estimates derived from 10 Be measurements of fluvial sands. The quasi-validated model simulation was subsequently used to make new testable predictions about the timing and location of aggradation and erosion phases for three locations along the Allier river. The validated simulations predict that along the Allier, reach-specific dynamics of incision and aggradation, related to the variations in sediment supply by major tributaries, cause relevant differences in the local fluvial terrace stratigraphy. Copyright © 2016 John Wiley & Sons, Ltd.

The objective of this paper is to make a detailed and multiproxy geomorphological study of the middle section of Amaicha River in Northwest Argentina. The obtained evolutionary model and chronological context will be linked with previous models to include the study area in a regional context. Finally, our model will be used as a morphochronological base to contextualize the lithic materials found in an area which previously lacked stra- tified records and absolute datings. The geomorphological study shows the high dynamic of the sector recorded in the ravine deposits during the Holocene. This process is reflected by the aggradation/degradation stages. A basal unit chronologically assimilated to the Pleistocene (Pl unit) is overlapped by four Holocene morphosedi- mentary units (H1 to H4). These units are arranged as terraces following an alternating succession of aggradative and degradative phases. The interbedding of tephra layers of known age, as well as radiometrically dated peat levels and soils, enables a very complete chronology of the Holocene sequence to be made. Lithic artifacts were found in the s1 soil, dated to 5468?4875 cal BP, providing one of the few records of stratified archaeological sites in the region for those times. This paper constitutes an initial approach in the development of a regional evo- lutionary model covering the period from the Late Pleistocene until the present. Fil: Sampietro Vattuone, Maria Marta. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán; Argentina. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Laboratorio de Geoarqueología; Argentina Fil: Peña Monné, José Luis. Universidad de Zaragoza; España Fil: Báez, Walter Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Bio y Geociencias del NOA. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Museo de Ciencias Naturales. Instituto de Bio y Geociencias del NOA; Argentina Fil: Sola, Alfonso Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Bio y Geociencias del NOA. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Museo de Ciencias Naturales. Instituto de Bio y Geociencias del NOA; Argentina Fil: Somonte, Carolina. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Estudios Sociales. Universidad Nacional de Tucumán. Instituto Superior de Estudios Sociales; Argentina

This paper quantifies the changes and present status of mangrove forest in Indian part of Sundarban from 1975 to 2014 using Landsat MSS (1975), TM (1990), ETM (2002) and OLM (2014) satellite imageries. The study used two image processing techniques: Maximum Likelihood Classification for the Land use and land cover analysis and NDVI for the vegetation characteristics and their temporal changes. The research found that the area of mangrove gradually decreases from 203752 hector (44%) to 132723 hector (31 %) and the barren land increases from 15078 hector (2.86 %) to 37247 hector (7.12%) due to natural ( sea level rise, salinization etc.) and anthropogenic (livelihood collection and shrimp farming etc.) disturbances and continuous land reclamation. Other land use categories like agriculture, water body, and sand deposition have approximately remained constant. The NDVI values were changed significantly only in 1990 due to the landward migration and defragmentation of mangrove forest. However, the paper signifies that the forest cover is constantly evolving due to deforestation, aggradation, erosion and forest rehabilitation programs in the Indian Sundarban.

This paper explores the response of deltas to tidal reworking and discusses the conditions at which deltas may become strongly tide influenced or tide dominated. Three case studies are presented, from the Cretaceous Western Interior, the Devonian Baltic Basin and the Eocene Central Basin of Spitsbergen. All datasets contain extensive outcrop data, the Baltic Basin dataset also extensive core data. The paper aims to show that beyond the commonly recognized morphological features and the recognizable tidal facies, the main effects of tidal reworking of deltas are associated with delta clinoform morphology, delta lobe switching rates, delta progradation rates, and the nature of the delta plain. Strong tidal influence is here documented to promote subaqueous, rapid progradation of deltas, by efficiently removing sediment from river mouth and thus reducing mouth bar aggradation and fluvial delta plain construction rates. Such subaqueous progradation of the delta front is decoupled from shoreline progradation. The delta plain of such tide-dominated deltas consists of a few distributary channels and tidal flats. The delta front clinoforms become gentler and longer, as tidal currents efficiently transport sediment to the basin. Tide-dominated deltas tend to maintain a funnel shape and show low lobe switching rates, compared to fluvial-dominated and tide-influenced deltas. This paper emphasizes topographic restrictions or invaginations, caused by incision, delta-lobe deposition or tectonic uplift and subsidence, as significant controls on the occurrence of strongly tide-influenced deltas. The role of such topographic restrictions is twofold, by reducing wave energy and amplifying tidal energy. Significantly, such invaginations are not restricted to inner-shelf reaches as commonly assumed, but may also occur at the shelf edge, promoting tidal reworking of shelf-edge deltas. Moreover, in very shallow epicontinental seas, significant tidal reworking may occur throughout the basin evolution, independent on sea-level cycles or sediment supply.

The present work explores relations between stream power, braiding intensities and bank erosion in certain stretches of the Brahmaputra River. In this paper, an objective approach is presented to enable quantitative assessment of spatio-temporal behaviour of channel braiding process of the Brahmaputra River by using the Plan Form Index and corresponding estimation of stream power to establish a behavioural pattern of variability of potential energy expenditure. The braiding index is compared for discrete years to understand the morphological behaviour. Subsequently, a real time estimation of stream power for certain stretches of Brahmaputra River is done in order to analyse its variability in braiding intensity and bank erosion. The paper presents the dynamic behaviour of the channel pattern of the Brahmaputra River System in Assam valley of India over a time span of 18 years. The procedure addresses the selection of input parameters from digital satellite images, comprising scenes for the years 1990, 1997 and 2007 with specific dates, from Dhubri near Indo-Bangladesh Border to Upper Assam. Deployment of GIS technique has been made to extract the required parameters to derive Plan Form Indices for the entire study reach. Stream power estimation is done for corresponding latest floods and for corresponding dates of image scenes. The study indicated that due to consistent aggradation of riverbed inducing temporal declination of stream power, there is an occurrence of wide spread braiding. This in turn incurs substantial yearly land loss due to bank erosion, caused by flow concentrations due to temporal evolution of multiple channels in the Brahmaputra River.

Many drainage basins adjacent to the upper Tsangpo Valley on the southeastern Tibetan Plateau are pervasively gullied. These gullies expose a stratigraphic record alternating between slow aggradation and stability (i.e., soil development) for much of the Quaternary, suggesting that gullying is recent and unprecedented within at least the past 10–100 k.y. In this paper, we date the initiation of gullying at five sites in the region using optically stimulated luminescence (OSL). We also test alternative hypotheses for gully initiation using numerical landform evolution modeling. OSL ages constrain the initiation of gullying to be mid-to-late Holocene in age. This period coincides with the onset of pastoralism in the upper Tsangpo Valley. Numerical modeling suggests that a reduction in vegetation density during the colder, drier conditions of Pleistocene glacial intervals did not trigger gullying because the reduction in vegetation density and hence rates of colluvial deposition in valleys coincided with an unusually dry period less capable of significant fluvial erosion from valleys. As such, low-order valleys most likely did not incise prior to the mid-to-late Holocene because an approximate balance was maintained between colluvial deposition and fluvial erosion. Vegetation changes associated with the onset of pastoralism, however, may have triggered gullying because such changes lowered the rate of colluvial deposition in valleys and/or increased the rate of fluvial erosion in valleys. The results of this paper provide insight into the ways in which drainage basins respond to climatic and anthropogenic perturbations in semiarid climates of moderate relief and underscore the dramatic landscape responses that can occur when geomorphic thresholds are crossed.

Rivers with poorly-sorted bed sediment create their own stratigraphy as they deposit sediment. Prediction of the subsequent river degradation into its own deposit requires knowledge of the spatial structure of the grain size variation of the deposit. The ultimate goal of the present work is the development, testing and verification against experimental data of a numerical model of morphodynamics that can store stratigraphy into memory as it is created by aggradation, and can subsequently consume this stratigraphy if and when the river later degrades into the deposit. Such a morphodynamic model is tested using a surface-based bedload transport relation known to be applicable to the experiments considered here. Part 1 of a two-part paper addressing this issue describes the laboratory experiments and uses the experimental results performed at mobile-bed equilibrium to evaluate a bedload transport relation. In the companion paper, this bedload transport relation is installed into a morphodynamic model that sp...

The objective of this paper is to investigate and analyze the silting and subsequent aggradation of the irrigation canals in Žitný Ostrov (Rye Island). The irrigation canal network, located in Southern Slovakia, was built to provide for irrigation water and drainage in the region. The water level in the irrigation canals and groundwater level in Žitný Ostrov area affect each other. Because of this mutual interaction, it has been necessary to evaluate the impact of silting in the canal network due to the presence of the alluvials. Water surface elevations in Danube River affect groundwater infiltration from the Žitný Ostrov aquifer, in and out of the canals, and causes fluctuation of the flow in the canals. The amount of groundwater infiltration is a function of the silt hydraulic conductivity. Tests were done in 1993 and 2004 to measure the silt thickness and granularity at 166 measurement points along approximately 77 km of the canal network. This paper discusses the change in silt thicknesses and silt v...

This paper presents a first-order HLLC (Harten-Lax-Van Leer with contact discontinuities) scheme to solve the Saint-Venant shallow-water equations, including morphological evolution of the bed by erosion and deposition of sediments. The Exner equation is used to model the morphological evolution of the bed, while a closure equation is needed to evaluate the rate of sediment transport. The system of Saint- Venant–Exner equations is solved in a fully coupled way using a finite-volume technique and a HLLC solver for the fluxes, with a novel wave-speed estimator adapted to the Exner equation. Wave speeds are usually derived by computing the eigenvalues of the full system, which is highly time-consuming when no analytical expression is available. In this paper, an eigenvalue analysis of the full system is conducted, leading to simple but still accurate wave-speed estimators. The new numerical scheme is then tested in three different situations: (1) a circular dam-break flow over movable bed, (2) an one-dimensional bed aggradation problem simulated on a 2D unstructured mesh and (3) the case of a dam-break flow in an erodible channel with a sudden enlargement, for which experimental measurements are available.

Purpose – The multidisciplinary Fluvalps‐3000 research project focuses on the variability of the Late Holocene and historical fluvial dynamics in alpine catchments. The purpose of this paper is to examine the potential of a 3,600 year‐long record composed from fluvial deposits for flood hazard assessment.Design/methodology/approach – The research is based on a multi‐proxy approach integrating methods of various disciplines as sedimentology, geochronology, pedology, geomorphology, palynology, history, and archaeology. This paper considers particularly the sedimentological and geocronological methods applied to the fluvial records of several key sections of the Lutschine and Lombach fan deltas.Findings – The sedimentary data of the high‐resolution fan delta record show up to seven major aggradation pulses from 3,600 cal yr BP to present. Furthermore, 19 minor burial episodes occur between 3,600 and 1,050 cal yr BP at average intervals between 113 years (Lutschine) and 105 years (Lombach) suggesting that agg...

The northern Wanganui Basin, New Zealand, is one of the key global sites for understanding marine cyclic sedimentation during the Quaternary. This paper presents the first evidence of marine cyclic sedimentation from its central-southern parts. Sedimentological, micropalaeontological and palynological analyses on a 280-m-deep borehole encountered units dating back to MIS 10. The sequence includes four marine cycles spanning MIS 9–5, which are overlain by terrestrial fluvial aggradation surfaces dating from MIS 4–2. Each marine unit represents a progressively shallowing depositional environment from the mid-shelf to coastal plain. This is overlain by a terrestrial sequence of lowstand fluvial terraces. Localized fault movements appear to have influenced the sedimentary character of the sequence during MIS 7a and 5e producing basement highs which provided protection to the shoreline. The cyclothems described in this paper now extend the already extensive, previously described record from MIS 17–10 to produce a combined eustatic record of Quaternary sea level change within the basin to MIS 5. They also provide an excellent example of the sedimentary response of a coastal basin to a progressive loss of sedimentation accommodation space.

A jokulhlaup burst from the head of Grasshopper Glacier in Wyoming's Wind River Mountains during early September 2003. Five reaches with distinct sedimentation patterns were delineated along the Dinwoody Creek drainage. This paper focuses on a portion of the jokulhlaup route where erosion of the forested banks created 16 large logjams spaced at longitudinal intervals of tens to hundreds of meters. Aggradation within the main channel upstream from each logjam created local sediment wedges, and the jams facilitated overbank deposition during the jokulhlaup. Field surveys during 2004 and 2006 documented logjam characteristics and associated erosional and depositional features, as well as initial modification of the logjams and flood deposits within the normal seasonal high-flow channel. Overbank deposits have not been altered by flows occurring since 2003. Field measurements supported three hypotheses that (i) logjams present along the forested portions of the jokulhlaup route are larger and more closely spaced than those along adjacent, otherwise comparable stream channels that have not recently experienced a jokulhlaup; (ii) logjams are not randomly located along the jokulhlaup route, but instead reflect specific conditions of channel and valley geometry and flood hydraulics; and (iii) the presence of logjams facilitated significant erosional and depositional effects. This paper documents a sequence of events in which outburst floodwaters enhance bank erosion and recruitment of wood into the channel, and thus the formation of large logjams. These logjams sufficiently deflect flow to create substantial overbank deposition in areas of the valley bottom not commonly accessed by normal snowmelt peak discharges, and through this process promote valley-bottom aggradation and sediment storage. Changes in the occurrence of glacier outburst floods thus have the potential to alter the rate and magnitude of valley-bottom dynamics in these environments, which is particularly relevant given predictions of worldwide global warming and glacial retreat. Processes observed at this field site likely occur in other forested catchments with headwater glaciers.

This paper assesses river channel management activities in the context of the interaction between coarse sediment delivery, climate change, river channel response and flood risk. It uses two main sources of evidence: (1) an intensive instrumentation of an upland river catchment using both traditional hydrometric and novel sediment sensing methods; and (2) a sediment delivery model that combines a treatment of sediment generation from mass failure with a treatment of the connectivity of this failed material to the drainage network. The field instrumentation suggests that the precipitation events that deliver sediment from hillslopes to the drainage network are different to those that transfer sediment within the network itself. Extreme events, that could occur at any time in the year (i.e. they are not dependent on wet antecedent conditions), were crucial for sediment delivery. However, sustained high river flows were responsible for the majority of transfer within the river itself. Application of three downscaling methods to climate model predictions for the 2050s and 2080s suggested a significant increase in the number and potential volume of delivery events by the 2050s, regardless of the climate downscaling scenario used. First approximations suggested that this would translate into annual bed level aggradation rates of between 0.10 and 0.20 m per year in the downstream main channel reaches. Second, the importance of this delivery for flood risk studies was confirmed by simulating the effects of 16 months of measured in-channel simulation with river flows scaled for climate change to the 2050s and 2080s. Short-term sedimentation could result in similar magnitude increases in inundated area for 1 in 0.5 and 1 in 2 year floods to those predicted for the 2050s in relation to increases in flow magnitude. Finally, we were able to develop an alternative approach to river management in relation to coarse sediment delivery, based upon reducing the rates of coarse sediment delivery through highly localised woodland planting, under the assumption that reducing delivery rates should reduce the rate of channel migration and hence the magnitude of the bank erosion problem. Thus, the paper demonstrates the need to conceptualise local river management problems in upland river environments as point scale manifestations of a diffuse sediment delivery process, with a much more explicit focus on the catchment scale, if our river systems are to become more insulated from the impacts of future climate changes.

We present a brief synthesis of the Quaternary fluvial record in the Lower Tagus Basin (central Portugal), concentrating on factors controlling infill and incision. The Holocene part of the record forms the focus of this paper and guides the questioning of the basic assumptions of the established Quaternary fluvial evolution model, in particular the link between sea-level change and fluvial incision-deposition. We suggest that several incision-aggradation phases may have occurred during glacial periods. Major aggradation events may overlap with cold episodes, while incision appears to concentrate on the warming limb of climate transitions. The complex stratigraphy of the Quaternary record in the Lower Tagus valley is influenced by repeated base-level and climate changes. This paper submits the first chronostratigraphic framework for valley fill deposits in the Lower Tagus area. Sea-level rise forced aggradation and controlled deposition of the fine-grained sedimentary wedge underlying the low-gradient Lower Tagus floodplain. Investigations have focused on the lower Muge tributary, where rapidly aggrading estuarine and fluvial environments were abruptly established (∼8150 cal BP) as sea level rose. Base level at the valley mouth controlled the upstream extent of the fine-grained backfill. Tidal environments disappeared abruptly (∼5800 cal BP) when the open estuary at the Muge confluence was infilled by the Tagus River. The decrease and final still stand of sea-level rise led to floodplain stabilisation with peat (∼6400–5200 cal BP) and soil formation (∼5200–2200 cal BP). Localised renewed sedimentation (∼2200–200 cal BP) is linked to human activity.

Central European Upper Jurassic sponge-microbial “reefs” are commonly regarded as compact, massive and homogenous facies bodies. A continuous study of borehole cores from SW Germany clearly shows a very systematic architecture of these “reefs” built by sedimentary cycles of various hierarchical levels. Altogether five orders of cycles can be distinguished: decimeter-scale microcycles building meter-scale mesocycles, which in turn are stacked to form several-meter thick macrocycles. These high-frequency cycles in turn are parts of basin-wide medium-scale and large-scale cycles reported in a previous paper. This paper documents the high-frequency micro-, meso- and macrocycles. Microcycles (0.1–0.8 m thick) usually have a sharp erosional base covered by reworked sponges, shells and intraclasts, interpreted as storm events. These bioclastic layers are colonised by a succession of thrombolitic and stromatolitic microbialites. Successive microcycles form distinct stacks that record gradually increasing and decreasing depositional energy, thus defining mesocycles (0.5–4 m thick). Several mesocycles construct macrocycles (3–25 m). The cycle stacking patterns were analysed by means of facies-proportion-diagrams. The dominant microscale cyclicity records changes in water agitation, possibly caused by fluctuating storm wave base. The sponge-microbial mounds could probably build up just to average storm wave base. Within the cycles of larger hierarchical levels the successive smaller-scale cycles show systematic trends in their symmetry and in thickness. This may be caused by variations in the ratio of accomodation space (and associated energy level) to carbonate production. External reef geometries (progradation, aggradation, retrogradation, condensation) can be related to internal cycle stacking patterns. To approximate the duration of the high-frequency cycles two different approaches were used. Firstly, the duration of cycles was determined with the help of published chronostratigraphic time scales. Secondly, cycle duration was estimated using published microbial reef growth rates. Both approximations result in ca. 0.4 Ma for the medium-scale cycles and 0.1 Ma for the macrocycles. Both are regionally correlatable, thus appear to be allocyclic in nature and probably are Milankovitch-driven. In contrast, the microcycles are only locally correlatable and thus indicate an autocyclic (storm-induced) nature. This study poses the question if not more of the apparently homogenous “reef bodies” of other settings and geological ages may possibly also show internal high-frequency cycles.

The quantitative modelling of fluvial reservoirs, especially in the stages of enhanced oil recovery, requires detailed three-dimensional data at both the scale of the channel belt and within-channel. Although studies from core, analogue outcrop and modern environments may partially meet these needs, they often cannot provide detail on the smaller-scale (i.e. channel-scale) heterogeneity, frequently suffer from limited three-dimensional exposure and cannot be used to examine the influence of different variables on the process–deposit relationship. Physical modelling offers a complementary technique that can address many of these quantitative requirements and holds great future potential for integration with reservoir modelling. Physical modelling provides the potential to upscale results and derive reservoir information on three-dimensional facies geometry, connectivity and permeability. This paper describes the development and use of physical modelling, which employs generic Froude-scaling principles, in an experimental basin that permits aggradation in order to model the morphology and subsurface depositional stratigraphy of coarse-grained braided rivers. An example is presented of a 1:50 scale model based on the braided Ashburton River, Canterbury Plains, New Zealand and the adjacent late Quaternary braided alluvium exposed in the coastal cliffs. Critically, a full, bimodal grain size distribution (20% sand and 80% gravel) was used to replicate the prototype, which allows the realistic reproduction of the surface morphology and importantly permits grain size sorting during deposition. Uncertainties associated with the compression of time, sediment mass balance and the hydrodynamics of the finest particle sizes do not appear to affect the reproducibility of stratigraphy between experimental and natural environments. Sectioning of the preserved sedimentary sequence in the physical model allows quantification of the geometry, shape, spatial distribution and internal sedimentary structure of the coarse- and fine-grained facies. A six-fold facies scheme is proposed for the model braided alluvium and a direct link is established between the grain size distribution and facies type: this allows permeability to be estimated for each facies, which can be mapped onto two-dimensional vertical cross-sections of the preserved stratigraphy. Results demonstrate the dominance of four facies based on permeability that range over three orders of magnitude in hydraulic conductivity. Quantification of such variability, and linkage to both vertical proportion curves for facies distribution and connectivity presents significant advantages over other methodologies and offers great potential for the modelling of heterogeneous braided river sediments at the within channel-belt scale. This paper outlines how physical models may be used to develop high-resolution, geologically-accurate, object-based reservoir simulation models

The present paper deals with the historical evolution of the northern Bay of Cadiz (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), Dona 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.

The Glen Canyon Dam, located in the northeastern corner of Arizona, is operated to satisfy peak power demands of neighboring states. The discharge regime of the dam is such that the river stage in the Colorado River downstream of the dam varies diurnally as much as 4 m in some sections. It is alleged that these fluctuations of the river stage are responsible for the destruction of sandbars and, as a result, the loss of the extant biomass and the reduction of recreational facilities. In this paper, an analysis is developed to determine the equilibrium slope below which slope failures (mass wasting, bank failures) due to seepage of bank‐stored water would be unlikely. The sediments enclosed by the equilibrium seepage slope (range 11°–14° for the sediments downstream of the Glen Canyon Dam) and the maximum slope angle (range from 26° to 32°) is subjected to ongoing aggradation and erosion. Field data from ground surveys support the analysis described in this paper.

Branney and Kokelaar (1992) emphasized that many features of pyroclastic flow deposits largely record the last processes involved in their formation, so Wolff and Turbeville's glib reminder of this philosophy at the end of their comment is quite unnecessary. Many structures in high-grade ignimbrites record non-particulate flow that occurred some considerable time after particulate aggradation ceased. This is not in question, and we pointed this out in our paper. It is the earlier deposition and deformation history of rheomorphic ignimbrites that is at issue. This is the aspect that bears more widely on the nature of pyroclastic flows and related eruptive phenomena. In another paper (Branney and Kokelaar 1994) we have documented evidence for hotstate remobilization and deformation of some stationary rheomorphic ignimbrites by post-emplacement disturbance (caldera collapse). However, in Branney and Kokelaar (1992) we provided evidence that shows that for most rheomorphic ignimbrites it is inappropriate to assume a twofold flow history (of hot remobilization after an initial flow came to rest). Progressive aggradation and agglutination provide the most straightforward explanation for many of the markedly irregular vertical variations in welding intensity characteristic of high-grade ignimbrites, just as progressive aggradation best accounts for vertical variations in sedimentary lithofacies and/or in chemical composition in other ignimbrites.

Many lowland rivers in the United Kingdom, including the Nene, Soar and Severn, have layered floodplains with a basal gravel of Pleistocene or Late glacial age and a structureless silty clay superficial unit burying the entire former floodplain. This burial is illustrated by the existence of variable, mixed and pedologically disturbed sediments and palaeo landsurfaces between the basal gravels and superficial silty clay. This paper presents a comparison of the pre- and post-late Holocene palaeo landsurfaces and palaeochannels using data from the Nene, Soar and Severn valleys. From this comparison it is argued that during the mid to late Holocene (ca 4500 yr BP to 2500 yr BP) floodplains and river channels underwent a metamorphosis. This is indicated by accelerated vertical accretion, a reduction in floodplain relative relief, changed floodplain soil conditions, a reduction in channel W/D ratios and a resultant increase in the silty clay proportion of channel perimeter sediments. There are indications that hydrological change preceded this metamorphosis but the primary cause was an increase in fine sediment supply during the later Holocene and a disequilibrium between channel bed and floodplain aggradation rates resulting in relative incision. This metamorphosis, which is explained in this paper by the proposed stable-bed aggrading-banks model (SBAB), is the key factor in the Holocene evolution of low-energy floodplain systems in the United Kingdom, upon which more subtle short-term fluctuations are superimposed.

The El Tigre archaeological site (39°46′49″ S; 62°22′32″ W) is located in the south of Provincia de Buenos Aires, Argentina, on an ancient delta of the Rio Colorado. Its sedimentary sequence shows periods of landscape stability and soil formation processes during the period ca. 1,000–400 years bp. The aim of this paper is to investigate the evolutionary history of the vegetation in order to understand palaeoenvironmental changes during the late Holocene. The study of microremains, mainly phytoliths, from the sedimentary sequence indicates that cold and dry conditions predominated at 2,700–2,200 cal bp, from deposition of non-pedogenetic, aggradational sediments in arid or semi-arid environments and/or sparse vegetation cover. Then the climate became much warmer at ca. 2,200–1,200 cal bp, with greater availability of moisture and the presence of xerophytic shrubs and halophytic grasslands, and also extra-regional trees and shrubs. The records indicate that for ca. 1,500–300 cal bp the climate conditions changed to temperate with periods of greater water availability and the presence of a saline steppe and a greater abundance of Monte-Caldenal scrub vegetation elements. This climatic trend is also in agreement with the soil formation processes defined in the archaeological site sequence. The upper layers of the El Tigre site show lower temperatures in the last 300 years, accompanied by variations in the availability of moisture, with alluvial processes characterized by the presence of saline grasslands with xerophytic shrubs and an increase in Asteraceae and Poaceae, continued by the recent top samples with ruderal communities and sandy grasslands.

The aim of this paper is to determine the extent to which “raised” channel systems may be used as indicators of long-term paleohydrologic change, and hence of broader paleoenvironmental changes, in arid areas during the Cenozoic. The paper reviews the paleohydrologic significance of former drainage systems in arid areas, and demonstrates the application of paleohydrologic methods to the analysis of the long-term evolution of a complex series of exhumed, multistorey, raised channel systems in interior Oman. The paper discusses the range of possible autocyclic and allocyclic controls on changes in channel behaviour through time, as a means of establishing the paleoenvironmental significance of observed changes in paleochannel pattern, morphology, sedimentology and stability. The paper identifies some of the major allocyclic controls, including climatic changes, and particularly the seasonality, magnitude, frequency and distribution of rainfall events during the Cenozoic, together with the degree of continentality and hence the strength and persistence of arid wind systems. Base-level changes, due to eustatic fluctuations and/or tectonic activity, may also act to control long-term patterns of aggradation followed by large-scale landscaping lowering. However, long-term fan ageing associated with progressive aggradation and steepening of paleochannel systems, may also eventually lead to fanhead trenching, independent of any external controls. In addition, progressive expansion of the drainage network and resulting river capture, can lead to marked increases in water and sediment supplies to the fluvial system. The paper also emphasizes the difficulties involved both in differentiating the wide range of possible controls on paleohydrologic response, and also in developing an accurate and precise chronology for desert paleodrainage systems, and in their correlation with non-fluvial sedimentological sequences. The raised channel systems of interior Oman consist of heavily desert varnished chert-and/or ophiolite-rich gravels, dating from some time during the Plio-Pleistocene period. The paleochannels from sinuous gravel ridges rising The observed changes have resulted from a complex combination of both internally and externally generated environmental changes during the Cenozoic. Progressive extension of the drainage network on to the ophiolite massif of the mountain source area resulted in river capture and a concomitant increase both in paleodischarges and in supplies of ophiolitic sediments to the paleodrainage system. The early sinuous channels may have developed under a humid to sub-humid climate, in which perennial or seasonal flows allowed the distinct meander paleochannels to form. Ephemeral flows, characterized by flash flood regimes, were probably associated with the later distributary systems, which may reflect semi-arid to arid climatic conditions. The large-scale deflation of the interfluve sediments, which resulted in the eventual exhumation of the cemented, gravel-capped, multistorey paleochannel sequence, is also likely to have occurred during periods of marked continentality, probably during periods of low sea-level associated with the Quaternary glaciations.

Explosive eruptions can severely alter the boundary conditions of fluvial systems around volcanoes by depositing large volumes of erodible fragmental material, increasing erosion rate and drainage mass flux (water and sediment) in the affected basin. In this paper, the environmental response to the 13 ka Croscat Violent Strombolian eruption in the Garrotxa Volcanic Field (NE Spain) has been investigated using a stratigraphic approach. Volcaniclastic material was mainly delivered at headwater tributaries (Les Tries plain in the Ser river basin) of the Fluvia River, one of the main drainage systems of NE Spain. Deposits in the Les Tries valley was initially reworked by hyperconcentrated-flows to braided stream-flows and by debris-flows involving mixed terrains (volcaniclastic materials and sands–gravels of the Eocene sedimentary basement) as registered in the stratigraphic record. The erosive pattern observed at the Les Tries valley reflects the erosion model of well-sorted and coarse-grained deposits (as the tephra deposited during the Violent Strombolian phase of the Croscat eruption), in which deep gullying and downstream aggradation are typically retarded where coarse tephra deposits remained highly permeable. Moreover, the Croscat eruption occurred soon after the Last Glacial Maximum, implying the shift from dry to wet conditions during the remobilization of the Croscat tephra. In this framework, the semiarid conditions retarded soil stabilization, driving the development of hyperconcentrated-flow-dominated alluvial fans, whereas the more humid environmental conditions favoured the partial stabilization of loose pyroclastic material, until it is periodically remobilization by mass-wasting processes as debris-flow-dominated lahars.

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.

[The Po River Lowstand Wedge (PRLW) of the central Adriatic Sea is made up of stacked alternated clinothems (Type A, B and C clinothems) that show different amount of aggradation of their topsets (e.g. Pellegrini et al., 2018). In this paper, we present novel sedimentological and paleontological analyses and discuss the processes responsible for the observed successions. We detail the character of the clinoforms deposited at the shelf‐edge, discussing the importance of hyperpycnal and storm‐enhanced sediment‐gravity flows in controlling the lithologic assemblage of the different tracts of the compound clinoforms. More in general, we show that, when the fine details of prograding clinoform units are investigated, the processes that lead to margin outbuilding are more complex than usually envisaged. , Abstract Clinoforms with a range of scales are essential elements of prograding continental margins. Different types of clinoforms develop during margin growth, depending on combined changes in relative sea level, sediment supply and oceanographic processes. In studies of continental margin stratigraphy, trajectories of clinoform ‘rollover’ points are often used as proxies for relative sea‐level variation and as predictors of the character of deposits beyond the shelf‐break. The analysis of clinoform dynamics and rollover trajectory often suffers from the low resolution of geophysical data, the small scale of outcrops with respect to the dimensions of clinoform packages and low chronostratigraphic resolution. Here, through high‐resolution seismic reflection data and sediment cores, we show how compound clinoforms were the most common architectural style of margin progradation of the late Pleistocene lowstand in the Adriatic Sea. During compound clinoform development, the shoreline was located landward of the shelf‐break. It comprised a wave‐dominated delta to the west and a barrier and back‐barrier depositional system in the central and eastern area. Storm‐enhanced hyperpycnal flows were responsible for the deposition of a sandy lobe in the river mouth, whereas a heterolithic succession formed elsewhere on the shelf. The storm‐enhanced hyperpycnal flows built an apron of sand on the slope that interrupted an otherwise homogeneous progradational mudbelt. Locally, the late lowstand compound clinoforms have a flat to falling shelf‐break trajectory. However, the main phase of shelf‐break bypass and basin deposition coincides with a younger steeply rising shelf‐break trajectory. We interpret divergence from standard models, linking shelf‐break trajectory to deep‐sea sand deposition, as resulting from a great efficiency of oceanographic processes in reworking sediment in the shelf, and from a high sediment supply. The slope foresets had a large progradational attitude during the late lowstand sea‐level rise, showing that oceanographic processes can inhibit coastal systems to reach the shelf‐edge. In general, our study suggests that where the shoreline does not coincide with the shelf‐break, trajectory analysis can lead to inaccurate reconstruction of the depositional history of a margin.]

River channels have been affected by climate changes and human interventions such as channelization, dam, gravel and sand mining and land use changes. Dam changes water and sediment transport in river systems. These changes are as one of the most important factors affecting upstream and downstream river morphology. The aim of this paper is to explain the effect of Taleghan dam (it was constructed from 2001-2006) on upstream of Taleghan River over the period 2000–2017. Taleghan River is very important river in the Central Alborz of Iran. For this reason, Taleghan River was divided 2 reaches as control reach and backwater reach. Channel morphology have been investigated using historical aerial photographs, remote sensing images and field observations. Also channel width, sinuosity index, and particle size distribution were calculated for two reaches pre and post-dam construction. Results showed that the channel width was increased in the post-dam period. Widening was dominated in the backwater and the control reaches but increasing in the channel width in the backwater reach is more than the control reach. the channel width has been increased due to the impact of the dam and flood events. Also the results of grain size distributions showed that dam affects the grain size distribution and leads to an increase in the fine particle size. Finally, the channel adjustment (aggradation and widening) in upstream of Taleghan River may cause floodplain inundation and damage to agriculture and residential area in floodplain.

The Ganos Fault, a part of the Northern strand of the North Anatolian Fault system, is an active- strike slip fault and divides the narrow NW shelf of the Sea of Marmara into two parts near the town of Gaziköy. This paper presents recently collected shallow high-resolution seismic data to discriminate the sedimentary successions, each characterized by distinctive stratigraphic patterns on both sides of the Ganos Fault. Two main units, namely U1 and U2, and three para-sequences (U1a, U1b and U1c) were identified, depending on their internal reflection patterns, accommodation depths as well as the presence of conformity and the unconformity surfaces. The thickness of Unit U1 reaches its maximum at the northern side of the Ganos Fault; it is much thinner to the south. The para-sequences of U1b and U1c have “progradation” and “aggradation to progradation” depositional characters, respectively. This probably implies fluvial deposition controlled by sea- level fluctuations. Unit U1b can only be observed at the northern side of the Ganos Fault, while Unit U1c at the southern side. Units U1a and U1b were deposited during the transgressive system tract, while Unit U1c was deposited during a sea-level fall and/or a lowstand phase marked by an erosional surface. The marine terraces in the study area are shallower than those along the northern shelf of the Sea of Marmara, possibly due to successive tectonic displacements along the Ganos Fault, which also controls the distribution and thickness of the parasequences identified in this study.

A reduced-complexity aeolian dune stratification model is developed and applied to explore the role of dune morphodynamics in the creation of synthetic sections of aeolian stratigraphy originating from three sets of environmental forcing: 1) steady wind transport capacity, 2) steady bed aggradation and variable wind transport capacity, and 3) steady wind transport capacity and bed aggradation. In each scenario, the forward motion of initial, highly disorganized dunes generates a significant record exclusively containing autogenic signals that arise from early dune growth, deformation, and merging. However, continued dune growth scours deeply, and shreds all records of early dunes. Afterward, dunes self-organize into quasi-stable groups. Forward motion of dune groups creates, truncates, and amalgamates sets and co-sets of cross-strata, quickly forming a second, significantly more robust stratigraphic record, which preserves a comingling of signals sourced from ongoing autogenic processes and each scenario's specific set of environmental forcings, the allogenic boundary conditions of the sand sea. Although the importance of self-organization on modeled aeolian stratification is clear in the few presented scenarios, self-organization may be throttled via variability in environmental forcings, as thoroughly documented in a companion paper (Cardenas et al., this issue). Therefore, additional work is warranted because this numerical experiment only begins to sample possible sets of environmental forcing, boundary conditions, and initial conditions, geomorphic responses, and consequential preservation possible in the presented surface-stratigraphic bedform modeling framework.

The stratigraphic architecture of aeolian sandstones is thought to record signals originating from both autogenic dune behavior and allogenic environmental boundary conditions within which the dune field evolves. Mapping of outcrop-scale surfaces and sets of cross-strata between these surfaces for the Jurassic Page Sandstone near Page, Arizona, USA, demonstrates that the stratigraphic signature of autogenic behavior is captured by variable scour depths and subsequent fillings, whereas the dominant signatures of allogenic boundary conditions are associated with antecedent surface topography and variable water-table elevations. At the study area, the Page Sandstone ranges from 55 to 65 m thick and is separated from the underlying Navajo Sandstone by the J-2 regional unconformity with meters of relief. Thin, climbing sets of cross-strata of the basal Page representing early dune-field accumulations fill J-2 depressions. In contrast, the overlying lower and middle Page consist of cross-strata ranging from less than 1 to 15 meters thick (average 2.44 m), and packaged between outcrop-scale bounding surfaces, though parts of the lower Page are bounded from beneath by the J-2. These bounding surfaces have been previously correlated to highstand deposits of the adjacent Carmel sea and at this site possess up to 13 meters of erosional relief produced by dune scour. Notably absent in packages of cross-strata bounded by these outcrop-scale surfaces are strata of early dune-field accumulations, any interdune deposits, and climbing-dune strata. Instead, these packages preserve a scour-and-fill architecture created by large dunes migrating in a dry, mature, dune field undergoing negligible bed aggradation. Any record of early phases of dune-field construction for the lower and middle Page are interpreted to have been cannibalized by the deepest scours of later, large dunes. Interpretations are independently supported by the relatively large coefficients of variation (cv) in middle Page set thicknesses (cv = 0.90), which are consistent with set production by successive deepest trough scours, the relatively low coefficient of variation for the depression-filling basal Page and lower Page sets consistent with a significant component of bed aggradation in J-2 depressions (cv = 0.64 and 0.49), and the fit of set thickness distributions to established theory. Numerical modeling presented here and more completely in the companion paper demonstrates how this cannibalization of early-phase stratigraphy is an expected outcome of autogenic dune-growth processes, and that early-phase strata can be preserved within antecedent depressions. Relative rise of the inland water table from basin subsidence and changing Carmel sea level forced preservation of 5–6 stacked packages composed of scour-and-fill architecture. Without these allogenic forcings, the Page would be little more than an erosional surface.

One of the most powerful eruptions of the Holocene, known as the Samalas eruption, had a VEI of 7 and took place on Lombok, eastern Indonesia in 1257 CE. Thick tephra fall covered the entire island, and pyroclastic density currents (PDCs) up to 50 m thick buried almost half of Lombok. Until now, there has been no detailed study of the geomorphological evolution of Lombok related to this eruption, especially for the eastern part of Lombok. The main goal of this paper is therefore to reconstruct the paleo-topography on the eastern part of Lombok before the eruption of the Samalas volcano in 1257 CE, and to analyse the subsequent landscape evolution following this eruption. Data were collected from more than 1300 points in order to gather geomorphological, geological, and geochemical information for the eastern part of Lombok over the last millennium. Data were obtained from wells (which are widespread in the studied area), natural outcrops (mainly cliffs along the shoreline and the rivers), and human-made outcrops in quarries, as well as from the two-dimensional resistivity profiling (Dipole-dipole array) carried out on eastern Lombok in 2016 and 2017. We estimate that 4435 ± 5.5 × 106 m3 of pumice-rich PDC, over a surface of 171 km2, buried the eastern part of Lombok in the aftermath of the 1257 CE eruption, and as a result of this rapid pumice-rich PDC deposition there has been some aggradation of the shoreline at some points, resulting in most of the pre-1257 coral reef being buried. After several intense rainfall events, the deposited volcanic material was probably eroded during the first decades following the 1257 CE eruption by mountain streams, producing lahars. We estimate that the remaining volume of pumice-rich PDC deposits following this erosion is 625 ± 5.5 × 106 m3 over a surface of 89 km2, which is equivalent to 14% of the initial volume.

Massive bed degradation (20 m in 7 years) has been observed in the Shi‑ting River, Sichuan Province, China, since the 2008 Wenchuan Ms. 8.0 earthquake. The reason for the massive bed degradation has not been well understood. A hypothesis has been proposed that relates bed degradation to the augmentation of sand supply after the earthquake. The effect of sand on gravel mobility (magic sand effect) has long been observed in laboratory experiments. In this paper, we study whether the augmentation of sand supply and its magic sand effect can lead to the observed massive degradation at decadal scales. A one-dimensional river morphodynamic model is implemented to study the problem in general at field scale and in context of the gravel-bed Shi‑ting River. Sediment transport is calculated with the Wilcock and Crowe (2003) relation, in which the magic sand effect is explicitly embedded in terms of a function relating reference Shields number to the surface sand fraction. We find that the augmentation of gravel supply leads to bed aggradation, whereas the augmentation of sand supply can indeed lead to bed degradation and surface fining. The magnitude and timescale of bed degradation are not sensitive to the sand supply rate but are sensitive to the flood intermittency factor, i.e., the fraction of time the river is in flood. However, an unrealistic flood intermittency factor (≥0.3) would be required in order to match the observed timescale of bed degradation, thus indicating that the magic sand effect might not be the governing reason for massive bed degradation in the Shi‑ting River, and by implication in gravel-bed rivers in general. Our simulation results also indicate that despite the fact that magic sand effects are not explicitly included in most sediment transport relations, they are at least partly built in via the hiding function that is contained in most sediment transport relations for gravel-sand mixtures. While here we use the Shi‑ting River as an example, our results have applicability to gravel-bed rivers subjected to augmentation in sand supply in general.

This paper discusses successive changes in the evolution of the fluvial system observed throughout the Blądzikowo Formation at the Mrzezino key site in northern Poland. The study focuses on the development of fluvial sedimentation during Marine Isotope Stage 7. The sedimentary record of the Pleistocene at the study site shows a well-developed sequence that is over 30 m thick. The Blądzikowo Formation shows a quick evolution of the fluvial system from a high-energy sandy braided river, to a meandering sandy river and, finally, to a low-energy meandering/anastomosing river with significant suspension settling. This transition is explained as a decrease in flow energy, increase in aggradation ratio and expansion of accommodation space during deposition time. A change in the fluvial system has not been manifested in the variations of the plant cover. Palynological analysis indicates that climate conditions were generally stable, cool and humid (boreal). Sediment transport occurred towards the N-NW, through a valley with a NW-SE axis. Infrared optically stimulated luminescence (IR-OSL) dating shows the sequence formed from 225.6 ± 17.2 to 210.5 ± 16.6 ka. Well preserved fluvial cycles and 35 m of thickness suggest the intensive accumulation of the Blądzikowo Formation with decreasing ratio of lateral erosion. It suggests an increasing influence of base level rise on evolution of fluvial system, mostly during MIS 7.

The concept of “Carbonate Factory” was introduced to describe areas of carbonate production and accumulation. In this paper, the “Ooid Factories” is used to analyze extensive Griesbachian (Triassic) oolite deposits in South China that, along with microbialites and lime-mud deposits from different carbonate depositional environments. Late Permian tropical shallow-water skeletal factories (dominant by calcareous algae, sponge, and other associated organisms) collapsed in pace with the most severe mass extinction event, and were rapidly replaced by mud-mound factories (microbialite and lime-mud deposits) and subsequent ooid factories in shallow-water circumstances of Griesbachian. Meantime, temporal nutrient-rich and high-temperature conditions probably delayed re-establishment of tropical shallow-water skeletal factories. As an elementary unit of ooid factories, Lower Triassic oolites have diagnostic characteristics of ooid fabrics (alternatively dark- and light-colored laminae), size ranges (1–5 mm), and grain compositions (pure ooids, and only a few gastropod and bivalve fragments). Continuous aggradational and progradational oolite sequences caused extensive oolite accumulations that significantly contribute to the development of platform architecture with the collaboration of mud-mound factories (mainly line-mud deposits) in South China, through the evolution of low-angle or homoclinal ramps in the early Griesbachian to distally steepened ramps or flat-topped shelves in the late Griesbachian. Moreover, ooid factories also developed in Western Tethyan, Cimmerian, and Arabian carbonate platforms within low latitudes of the Tethyan Ocean during the Griesbachian. It is suggested that extreme hothouse climate with (seasonal) dry conditions in low latitudes significantly facilitated the extensive carbonate production of ooid factories at that time due to the strong linear relationship between surface seawater temperature and carbonate saturation state.

The 2008 Wenchuan Ms 8.0 earthquake caused severe destruction in the mountainous areas of Sichuan Province, China. Landslips and mass movements led to substantial amounts of loose sediment accumulating in valleys that subsequently led to widespread riverbed aggradation. In addition to erosion and deposition hazards, this aggradation produced rivers in earthquake affected areas that were more susceptible to flash floods under extreme rainfall events. However, fluvial processes and sediment movement after a major earthquake, as well as the re-working of sediments in future events, are not well studied. In this paper, we investigate the response of sediment and river channel evolution due to different rainfall scenarios after the Wenchuan earthquake by using the CAESAR-Lisflood model. This is the first time that this landscape evolution model has been employed to explore material migration processes in a post-earthquake area, and to test its applicability to real landform changes in the studied catchment. The CAESAR-Lisflood model is well suited to simulate sediment movement, particularly the fluvial processes driven by severe rainfall after an earthquake. We calibrated the model parameters to the 2013 extreme rainfall event using high-resolution satellite images. Under rainfall scenarios of different intensity and frequency over a 10-yr period, landform evolution and sediment migration in the post-earthquake area were simulated. The results showed that the sediment yield could be significantly increased under enhanced and intensified rainfall scenarios compared to a normal rainfall scenario. These findings are of importance for the planning of post-earthquake rehabilitation and regional sustainable development, which considers risk prevention and mitigation.

The movement of sediment from source to sink in a watershed is a complex process with multiple interactions and feedbacks across scales. At small scales, the size characteristics of a sediment mixture affect the transport of that sediment through hiding and through the nonlinear effect of sand content on gravel transport. At large scales, the channel network itself, through network geometry and the spatial pattern of transport capacity, adds additional complexity in organizing sediment moving through the system such that aggradational hotspots can emerge. The purpose of this paper is to present a Lagrangian framework for exploring complexities of mixed-size sediment transport in gravel-bedded river networks. The present model builds off of previous network-based, bed-material sediment transport models; but key advancements presented herein (i) allow for a mixture of sediment sizes in the river network, (ii) incorporate a mixed-size sediment transport equation, and (iii) utilize a daily flow hydrograph to drive intermittent transport. The model is applied to the roughly 4700 km2 Methow River Basin in Washington State, USA, using simplified model inputs with the goal of illustrating the utility of the model for motivating future work.

Sand and gravels are basic construction raw material globally. With increased economic activity, rate of extraction of sand and gravels has gone up three folds during last two decades reaching 40 billion tonnes per year. Critical hot spots for sand extraction are China and India. Uncontrolled illegal sand mining is common – reduction in ground water level and water transparency, increased water turbidity, adverse impact on birdlife. It is estimated that every year 10 million cubic meters of sand is extracted in Morocco by sand mafias converting large sand beaches into rocky landscape. Singapore has extended its area by 20% by importing 517 million tonnes of sand over last 20 years from neighbouring countries. Some of the countries like India and Malaysia have developed river sand mining guidelines to ensure equilibrium of river, avoid aggradation of hydraulic structures, protection of rivers against erosion, and avoid water pollution. Principal of sustainability is based on equilibrium of meeting business objectives, environmental compliance and social compliance of various stake holders. Tipple bottom line pillars for sustainability include financial stability, environmental stewardship and social equity. For minimizing environmental effect due river sand mining, many countries have adopted technology of manufacturing sand through series of crushers – primary jaw crusher, secondary cone crusher and tertiary vertical shaft impact (VSI) crusher. Japan has developed V7 dry sand manufacturing technology. Manufacturing Sand (M-Sand) has comparable gradation with river sand. Various technical specifications of aggregates and M-Sand adopted by India and US are provided in this paper. There is need of creating R&D facilities in every region for sustainability to develop specifications of M-Sand based on available resources and meet local sand requirement.

This paper reconstructs the Quaternary aggradation and incision history of a debris flow/debris-charged flood-affected valley in order to detect the impact of climate on alluvial fan dynamics. We used optically stimulated luminescence (OSL) dating of quartz to determine the ages of alluvial fan terraces. Comparison between the aggradation and incision history and regional climatic records suggests that aggradation occurred in cold and/or dry climates, whereas incision is a feature of warm and wet climates. Cold climates lead to enhanced frost shattering, and dry climates cause deteriorated vegetation. Both effects caused surplus sediment, which was transported by infrequent flood discharges to form alluvial fan/terrace deposits. Incision during wet and warm climates is due to increased vegetation cover and an increase in the frequency of flood discharges. This relationship between climate and valley evolution is applied to assess future changes in the present active channel by considering recent climatic records. The results show that the valley channel is expected to experience net incision if the average temperature continues increasing while precipitation maintains at a constant level.

International audience; The retreat of glaciers in response to climate warming leads to substantial changes in meltwater and sediment yield. Glacial shrinkage also induces the emergence and growth of proglacial margin landforms which strongly affect water and sedimentary transfers from the glacier to the outwash plains. On a decadal-timescale, field observations show that outwash plains of retreating glaciers typically exhibit proximal incision which decreases in magnitude downstream and stops at an inflection point where aggradation begins. Nevertheless, there is a lack of knowledge about the rates and magnitude of this fluvial adjustment and the effects of the proglacial margin configuration on the temperance or the aggravation of this fluvial adjustment to glacier retreat. This paper investigates the proglacial rivers of 14 retreating glaciers in southeast Iceland over a post-Little Ice Age timescale, combining fluvial deposits mapping, lichenometric dating and long-profile measurements of proglacial fluvial terraces. Our results demonstrate that: (1) proximal incision, associated with distal aggradation and downstream migration of the inflection point is the dominant pattern of proglacial river response to post-LIA glacier retreat in Iceland; (2) estimated mean rates of downstream migration of the inflection point range between 5 and 46 m.a-1 ; (3) the downstream migration rate of the inflection point is positively correlated with the proportion of proglacial lakes within the glacier foreland. These findings suggest that proglacial margins dominated by proglacial lakes intensify the rates of proximal incision and inflection point migration

Managing tailings deposition in cold climate requires specific measures not to create permafrost. The risk of generating permafrost due to tailings deposition exists even in regions where permafrost would naturally not occur. Material being frozen during winter might not fully thaw in the following summer due to added height of the tailings on the surface. Such embedded layers of permafrost should be avoided especially close to tailing dams. Main reasons are to prevent impermeable layers in tailings facilities, and to reduce the risk of having implications if such layers thaw during warmer summers causing increase in pore water pressure, reduced effective stress, and increased water content. This paper presents a numerical study on the effects of tailings deposition in cold regions in relation to the potential formation of permafrost. Various deposition rates, schedules and tailings properties were evaluated. One-dimensional heat conduction analyses were performed with a temperature scenario representing a mine district in northern Sweden. Results show, that the thickness of permafrost layers increase with increased deposition rate and with increased water content. It was also shown that wet and loose tailings must be deposited in short periods during summer to avoid permafrost generation. In the case of dry and dense tailings more time is available for deposition in order not to cause aggradation of permafrost in the deposit. These findings can help mining operation to set up deposition schedules for tailings facilities in cold climate. For known tailings properties, results can be used to identify periods of the year when, and how much, tailings can be deposited in critical areas of a deposit in order to avoid permafrost formation.

Crushed-rock revetment embankments (CRRE) were the most commonly used structure in the construction of the Qinghai–Tibet Railway, and also is a main strengthening measure at the later period's maintenance. Numerical and short-time field monitoring results have confirmed the cooling effects of CRRE, but studies regarding the long-term embankment thermal regime and deformation are still required to fully evaluate their performance. This paper discusses the cooling effects and embankment settlement of a CRRE at the Qinghai–Tibet Railway by examining the ground temperatures and embankment deformation between the years of 2003 and 2014. The results indicate that the crushed-rock layer has lowered the permafrost temperatures beneath the embankment and promoted permafrost aggradation. The estimated annual heat budget of the permafrost beneath the embankment was negative during the studied time period, indicating the sustained cooling performance of the CRRE. Furthermore, although the embankment shoulders experienced settlement, this settlement was smaller than that of a traditional embankment with normal gravel soil fills. This study confirms the utility of the CRRE as an effective design and maintenance measure for roadbeds in warm permafrost regions.

Due to the periodic rising and falling of the reservoir water level, the rock–soil body of bank slope is constantly changing between the saturated and unsaturated status, which changes the limit equilibrium condition of the slope body, resulting in a large number of dormant landslide reactivation and new landslide generation after water impounding operation of the three gorges reservoir. Based on the long-term monitoring data of pore-water pressure, water content, reservoir water level, rainfall and landslide deformation, the deformation response regularity of Liujiaba landslide under the fluctuating reservoir level combined scenario is studied in this paper. The results show that the landslide deformation is mainly in the lower section affected by the fluctuation of the reservoir water. The slide deformation appears in the mid-early stage of the water level declining and during the running of 175 m water level. The deformation is gradually increasing from a slowly to rapidly stage, then slows down and gradually reduces to a relative stopped state. Considering that the variation of the saturation line in the landslide will be influenced by the water level fluctuation rate, the SEEP and SLOPE modules are used with Geo-studio software for the fluctuant reservoir level and response pattern of landslide deformation analysis. The study can be provided as a reference for landslides study of debris aggradational landslide.

This paper describes 64 experiments conducted in a sand-recirculating flume using coarse sand (d50 = 0.85 mm), investigating the interference of local scour between a circular pier (diameter D = 48 mm) and a downstream submerged weir (weir height z = 30 mm) with different separation distances L. The experimental results show that, for clear-water scour, the scour depth at the pier can be reduced by up to 54% by the downstream submerged weir when L = 0. This reduction decreases with increasing L until it approximately vanishes at L = 6D. For live-bed scour, besides the upstream bed aggradation, the downstream submerged weir can affect the local scour at a pier through two mechanisms: (i) superposition of local scour areas; and (ii) altering flow patterns. The mechanism (i) can increase the scour depth at the pier significantly when the pier is located in the upstream scour area of the submerged weir. The mechanism (i) vanishes at a distance L1, where the pier is located out of the upstream scour area of the submerged weir. The mechanism (ii) is similar to that of the clear-water scour tests, and can reduce the scour depth at the pier. The reduction effectiveness of mechanism (ii) decreases with increasing L until it becomes zero at a distance L2. Based on the experimental data, L1 and L2 are found to be 2D and 12D, respectively. For safe design, L1

This paper examines facies and stratigraphic relationships at the tip-out of a sequence boundary along the fluvial-to-marine transition zone of the Cretaceous Ferron Notom delta, Utah. Correlation of 11 measured sections shows that the sequence boundary underlies amalgamated fluvial deposits in more proximal parts of the valley, whereas the valley fill splits into a pair of fluvial channel facies separated by transgressive shoreface deposits in the transition zone. This indicates at least two episodes of downcutting and valley filling, and suggests a compound valley system. Thick sandy deltaic deposits are interpreted as the falling-stage and lowstand deposits farther downdip, fed by the rivers that cut the valley. Paleohydraulic calculations indicate that the valley-forming trunk channels were on the order of 5.5 m deep, and carried coarse sand with rare pebbles over a slope on the order of 0.0005. Corresponding backwater lengths were on the order of 10 km. Recent models show that channels in the backwater zone should experience greater levels of aggradation, versus rivers landward of the backwater, which may show greater lateral migration or incision, and these predictions are matched by our observations. In addition, tidal backwater effects are predicted to be on the order of a few kilometers. The valley-fill shows increasing aggradation and tidal facies in sections a few kilometers from the mapped shorelines, which suggests a short backwater length. The relatively short backwater also allows the rivers to bring coarser sand and gravel close to the shoreline.

Sun sheds were once used as an effective roadbed cooling technique in permafrost regions. Numerical and indoor-experiment results have confirmed the cooling effects of the sun-shaded embankments, but field-monitored data are still necessary to evaluate their long-term performance. This paper discusses the cooling effects of a sun shed over a section of the Qinghai-Tibet Railway embankment, by examining near-surface air and ground temperatures and the permafrost table depth at the shaded section, at an unshaded embankment section, and in surrounding natural ground. Monitoring results from 2006 to 2010 indicate that the sun shed has lowered near-surface air temperatures and underlying permafrost temperatures beneath the embankment, and promoted permafrost aggradation. The estimated annual heat budget of the permafrost beneath the sun-shaded embankment section has been negative over the past nine years, indicating the sustained cooling performance of the sun shed. This study confirms the utility of sun sheds as an effective design and maintenance concept for infrastructure embankments in warm permafrost regions, provided that the structure can resist harsh environmental conditions.

This paper examines the patterns of sediment transport in rivers in terms of the sources of sediment and its transport and deposition through the river network. The analysis is in the context of dramatic human influences on river sediment transport and how they might influence freshwater ecosystems. The review of Australian work shows that erosion of hillslopes and stream banks has greatly increased in historical times, supplying vast quantities of sediment to rivers, much of which is still stored within the river system. The stored sediment will continue to effect in-stream and estuarine ecosystems for many decades. In most Australian catchments the dominant source of sediment is streambank erosion. An analysis of historical channel widening suggests that a conceptual framework of relative stream power can explain the diversity of behaviour observed in the numerous case studies. Sediment delivery through catchments is considered first in a generic whole network sense, which emphasizes the crucial role played by riverine deposition in determining catchment sediment budgets. A method is then presented for analysing the diverse spatial patterns of sediment storage in any river network. Finally, the paper considers the temporal changes to channel morphology in response to a human-induced pulse of sediment.

This paper examines the patterns of sediment transport in rivers in terms of the sources of sediment and its transport and deposition through the river network. The analysis is in the context of dramatic human influences on river sediment transport and how they might influence freshwater ecosystems. The review of Australian work shows that erosion of hillslopes and stream banks has greatly increased in historical times, supplying vast quantities of sediment to rivers, much of which is still stored within the river system. The stored sediment will continue to effect in-stream and estuarine ecosystems for many decades. In most Australian catchments the dominant source of sediment is streambank erosion. An analysis of historical channel widening suggests that a conceptual framework of relative stream power can explain the diversity of behaviour observed in the numerous case studies. Sediment delivery through catchments is considered first in a generic whole network sense, which emphasizes the crucial role played by riverine deposition in determining catchment sediment budgets. A method is then presented for analysing the diverse spatial patterns of sediment storage in any river network. Finally, the paper considers the temporal changes to channel morphology in response to a human-induced pulse of sediment.