Abstract Bed material waves are temporary zones of sediment accumulation created by large inputs. Recent theoretical, experimental and field studies examine factors influencing dispersion translation bed in quasi‐uniform, gravel‐bed channels. Exchanges between a channel its floodplain neglected. Within these constraints, two influence relative rates translation: (1) interactions wave topography, flow load transport; (2) particle‐size differences original material. Our results indicate that...

divers typically exhibit a tendency for grain size to become finer in the downstream direction. Data set of large-scale experiments on aggradation heterogeneous gravel have recently available. These show substantial fining over several tens meters. Here decoupled numerical Tiodel bed and is developed an attempt test existing ransport model against experimental data. Generally good agreement found between predictions he observations absence all but trivial adjustments transport model. The...

Sediment often enters rivers in discrete pulses associated with landslides and debris flows. This is particularly so the case of mountain streams. The topographic disturbance created on bed a stream by single pulse must be gradually eliminated if river to maintain its morphological integrity. Two mechanisms for elimination have been identified: translation dispersion. According first these, high translates downstream. second it diffuses away. In any given both may operate. paper devoted...

Many dams have been removed in the recent decades U.S. for reasons including economics, safety, and ecological rehabilitation. More are under consideration removal; some of them medium to large-sized filled with millions cubic meters sediment. Reaching a decision remove dam deciding as how should be removed, however, usually not easy, especially dams. One major difficulty decision-making is lack understanding consequences release reservoir sediment downstream, or alternatively large expense...

We present results and analyses from flume experiments investigating the infiltration of sand into immobile clean gravel deposits. Three runs were conducted, each successive run with same total sediment feed volume, but a 10‐fold increase in rate. The highest rate produced less subsurface deposits than other two runs, which had approximately equivalent amounts infiltration. Experimental data, combined simple geometric relations physical principles, are used to derive describing saturated...

Sediment pulses in rivers can result from many mechanisms including landslides entering side slopes and debris flows tributaries. Artificial sediment be caused by the removal of a dam. This paper presents numerical model for simulation gravel bedload transport pulse evolution mountain rivers. A combination backwater quasi-normal flow formulations is used to calculate parameters. Gravel calculated with surface-based equation Parker 1990. The Exner continuity express mass balance at different...

The effectiveness of gravel augmentation as a river restoration strategy depends on the extent and duration topographic bed texture changes created by pulse added sediment. Previous work has emphasized strong tendency for natural sediment waves to propagate primarily dispersion; however, translation may occur additions armored channels downstream dams where sediments are finer than preexisting material. Here we report results laboratory investigation in which an immobile, documented spatial...

Mountain rivers in particular are prone to sediment input the form of pulses rather than a more continuous supply. These often enter landslides from adjacent hillslopes or debris flows steeper tributaries. The activities humans such as timber harvesting, road building, and urban development can increase frequency pulses. question how mountain accommodate thus becomes practical well academic significance. In part 1 [ Cui et al. , 2003 ], results three laboratory experiments on reported. It...

Abstract Accompanying its rapid urban development, prevalent flooding incidents have been occurring in China the past two decades with increasing frequency. Through a comparison generally accepted management practices, we (the authors) identified that lack of surface water runoff considerations (i.e., missing major drainage system stormwater system) and inadequate local mitigation are primary causes problems China, which turn is rooted planning stage city's development. Following...

Many rivers have an abrupt transition from gravel-bed to sand-bed morphology. In many cases the point of is neither prograding nor retrograding, but rather arrested in place. Two mechanisms are hypothesized as responsible for stabilizing gravel-sand transition, basin subsidence (or alternatively base level rise) and abrasion gravel. The companion paper offers a simplified analytical solution long profile river with such transition. This treatment allows direct insight into relation between...

Abstract Most rivers exhibit a tendency for the characteristic size of'the bed material to become finer in downstream direction. In addition, most river sediments also paucity of pea gravel range. Because this transition direction from gravel-bed stream sand-bed is usually rather abrupt, and often marked by discontinuity slope morphology as well. If front marking gravel-sand not prograde continuously point at which base level established, e.g. ocean, then some mechanism must operate arrest...

A theoretical model is developed to describe the process of fine sediment infiltration into immobile coarse deposits. The governing equations are derived from mass conservation and assumption that amount deposition per unit vertical travel distance deposit either constant or increases with increasing fraction. Model results demonstrate accumulation decreases rapidly depth substrate initially void sediment, which consistent experimental observations significant occurs only a shallow depth....

Abstract Sediment management is frequently the most challenging concern in dam removal but there as yet little guidance available to resource managers. For those rivers with beds composed primarily of non‐cohesive sediments, we document recent numerical and physical modelling two processes critical evaluating effects removal: morphologic response a sediment pulse, infiltration fine into coarser bed material. We demonstrate that (1) one‐dimensional pulses can simulate reach‐averaged transport...

Large quantities of fine sediment can be accumulated in reservoirs, and the potential impact their downstream release is often a great concern if dams are to removed. Currently, there no reliable numerical models simulate dynamics these sediments, mostly because following dam removal driven by rapid erosional process not addressed traditional transport theory. However, precise quantification rarely necessary evaluate environmental impacts alternative scenarios. Using Matilija Dam southern...

Abstract Sediment often enters rivers in the form of sediment pulses associated with landslides and debris flows. This is particularly so gravel‐bed earthquake‐prone mountain regions, such as Southwest China. Under circumstances, can rapidly change river topography leave repeated states gradual recovery. In this paper, we implement a one‐dimensional morphodynamic model response to pulsed supply. The validated using data from flume experiments, demonstrating that it successfully reproduce...

This paper presents sample runs of the Dam Removal Express Assessment Models (DREAM) presented in companion paper, Cui et al. (2006): DREAM-1 for simulation sediment transport following removal a dam behind which reservoir deposit is composed primarily noncohesive sand and silt, DREAM-2 upper layer gravel. The primary purposes here are to validate some assumptions used model provide guidance as how accurately field data should be collected. Sample indicate that grain size distribution most...

This paper presents The Unified Gravel‐Sand ( TUGS ) model that simulates the transport, erosion, and deposition of both gravel sand. employs surface‐based bed load equation Wilcock Crowe (2003) links grain size distributions in load, surface layer, subsurface with transfer function Hoey Ferguson (1994) Toro‐Escobar et al. (1996), a hypothetical sand function, functions for entrainment/infiltration from/into subsurface. is capable exploring dynamics distributions, including fractions...

Abstract Sediment waves or pulses can form in rivers following variations input from landslides, debris flows, and other sources. The question as to how cope with such sediment inputs is of considerable practical interest. Experimental, numerical field evidence assembled by the authors suggests that mountain gravel‐bed streams, show relatively little translation, instead mostly dispersing place. This research has recently been subject discussion. In particular it suggested (a) equations flow...

The 14-m-tall Marmot Dam was removed during the summer of 2007, and cofferdam protecting working area breached a storm on October 19, allowing approximately 750,000 m3 reservoir deposit to be eroded freely released downstream Sandy River. Prior removal, sediment transport models were developed predict dynamics both gravel sand, providing key pieces information for stakeholders regulatory agencies select most appropriate dam removal alternative. A monitoring program implemented following that...

One-dimensional numerical sediment transport models (DREAM-1 and DREAM-2) are used to simulate seven experimental runs designed examine pulse dynamics in a physical model of forced pool-riffle morphology. Comparisons with measured data indicate that DREAM-1 -2 closely reproduce the flux channel bed adjustments following introduction fine coarse pulses, respectively. The cumulative at flume exit simulation is within 10% values, DREAM-2 factor 2 values. Comparison simulated reach-averaged...

Abstract This paper describes the application of The Unified Gravel‐Sand (TUGS) model for simulation Sandy River, Oregon. TUGS employs Wilcock and Crowe's ( 2003 ) bedload transport equation gravel sand transport, is capable simulating dynamics bed material grain size distributions, including fractions in deposits. has been examined with three large‐scale flume experiments a flushing flow experiment good agreements profiles, characteristic sizes These examinations, along descriptions...