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Norman D. Smith

Bio: Norman D. Smith is an academic researcher from University of Nebraska–Lincoln. The author has contributed to research in topics: Sediment & Floodplain. The author has an hindex of 37, co-authored 65 publications receiving 5468 citations. Previous affiliations of Norman D. Smith include University of Illinois at Chicago & University of Illinois at Urbana–Champaign.
Topics: Sediment, Floodplain, Glacier, Levee, Aggradation


Papers
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Journal ArticleDOI
TL;DR: In this article, stability analyses of bifurcating channels suggest that thresholds in the relative energy slope and Shields parameter of the bifurlacing channel system are key factors.
Abstract: ▪ Abstract Avulsion is the natural process by which flow diverts out of an established river channel into a new permanent course on the adjacent floodplain. Avulsions are primarily features of aggrading floodplains. Their recurrence interval varies widely among the few modern rivers for which such data exist, ranging from as low as 28 years for the Kosi River (India) to up to 1400 years for the Mississippi. Avulsions cause loss of life, property damage, destabilization of shipping and irrigation channels, and even coastal erosion as sediment is temporarily sequestered on the floodplain. They are also the main process that builds alluvial stratigraphy. Their causes remain relatively unknown, but stability analyses of bifurcating channels suggest that thresholds in the relative energy slope and Shields parameter of the bifurcating channel system are key factors.

533 citations

Journal ArticleDOI
TL;DR: The Cumberland Marshes in east-central Saskatchewan, Canada, contain a variety of active and abandoned fluvial features, including straight to sinuous isolated channels, anastomosed channel systems, levees, and crevasse splays in addition to marshes, lakes and bogs.
Abstract: The Cumberland Marshes in east-central Saskatchewan, Canada, occupy over 5000 km2 and contain a variety of active and abandoned fluvial features, including straight to sinuous isolated channels, anastomosed channel systems, levees, and crevasse splays in addition to marshes, lakes and bogs In 1873, an avulsion of the Saskatchewan River diverted most of its flow into a portion of the Cumberland Marshes (locally termed the breakout area), and altered the alluvial terrain as the invaded wetlands adjusted to the influx of sediment and water These adjustments continue today, and so far over 500 km2 of wetlands have been affected by the avulsion Avulsion-controlled modification of the wetlands involves the initiation and evolution of crevasse splays and splay complexes Three intergradational forms are recognized, each associated with characteristic sand-body geometries Stage I splays are small, lobate in plan, crossed by unstable distributary channels, and form wedge-shaped sheets which depositionally overlie fine-grained, organic-rich wetland sediments Stage II splays and splay complexes evolve both spatially and temporally from Stage I splays They are larger, contain dense networks of anastomosed channels, and form disconnected tabular sand bodies or continuous sand sheets, some of which incise underlying wetland sediments Stage III splays develop from either Stage I or II splays and contain few but stable anastomosed channels that deposit isolated stringer sands encased in fine-grained floodplain sediments Although sand bodies deposited by splays comprise important components of the evolving floodplain, various fine-grained facies occurring in levees, shallow lakes, abandoned splay channels, and interchannel floodplains dominate the avulsion deposits The post-1873 record of deposition and terrain modification in the breakout area suggests four stages of floodplain evolution following avulsion In the initial avulsion stage, new channels and splay complexes increase in numbers rapidly as diverted discharge of water and sediment overwhelm the adjacent floodbasin The anastomosed stage is characterized by an approximate balance between rates of new channel and splay development, and abandonment of old ones This stage continues for as long as new floodplain areas are invaded The rate of new splay development eventually decreases as accessible floodplain becomes aggraded, forcing a higher rate of channel abandonment and concentration of remaining flow into fewer but larger channels (reversion stage) The result of reversion is eventual return to a single channel stage, completing the avulsive sequence and initiating a new alluvial ridge For the Saskatchewan River, this final-stage single channel will likely produce a meander belt which occupies only a portion of the more extensive avulsion belt which preceded it

523 citations

Journal ArticleDOI
TL;DR: Bar formation and sediment distribution patterns were examined in a 4-mile braided reach of the upper Kicking Horse River at Field, British Columbia, which was mainly supplied by meltwater from icefields straddling the continental divide at the British Columbia-Alberta boundary in the southeastern Canadian Cordillera as mentioned in this paper.
Abstract: Bar formation and sediment distribution patterns were examined in a 4-mile braided reach of the upper Kicking Horse River at Field, British Columbia, which is mainly supplied by meltwater from icefields straddling the continental divide at the British Columbia-Alberta boundary in the southeastern Canadian Cordillera. Marked diurnal variations in discharge, suspended sediment concentration, and water temperature occur during peak summer melting periods when rates of sediment transport and bar formation are greatest. Bed material is mostly limestone and dolomite gravel which undergoes rapid fining in the downstream direction. Gravel bars occurring in a wide variety of shapes and sizes comprise the dominant bed forms. Most exposed braid bars have undergone complex depositional and erosional histories and rarely show simple or consistent patterns of grain size or structures, either internal or superficial. Active bars with simple histories and predominantly depositional morphologies are termed "unit bars." Fo...

370 citations

Journal ArticleDOI
TL;DR: In this paper, three anastomosed river systems are described, each reach consists of an interconnected network of low-slope, narrow and deep, straight to sinuous, stable channels that transport coarse sand and gravel.
Abstract: Three anastomosed river systems are described. Each reach consists of an interconnected network of low-slope, narrow and deep, straight to sinuous, stable channels that transport coarse sand and gravel. Channels are separated by levees and wetlands composed of silt/mud and vegetation. Gravel-bed braided channels occur upstream from each anastomosed system, joined by a transitional reach comprising stable, elongate, silt islands within braided channels. The three anastomosed reaches have formed upstream from elevating base levels caused by deposition of alluvial fans across trunk valleys. Rapid aggradation of floodplain alluvium is confirmed by buried volcanic ash layers. Channel migration is inhibited by root-stabilized banks which, combined with rapid vertical aggradation, results in production of stringer-like, coarse-grained channel deposits surrounded by overbank fines in stratigraphic cross sections. Although it is unlikely that such small base-level controls (alluvial fans) could produce extensive anastomosed deposits, other mechanisms such as glacial moraines, isostatic rebound, or marine transgressions could provide plausible controls for yielding important contributions to the stratigraphic record.

313 citations

Journal ArticleDOI
TL;DR: In this paper, relative abundances of planar cross-stratification and horizontal stratification, as well as bed-relief indices were measured in sandstones and conglomerates of the Lower Silurian Shawangunk Conglomerate, Green Pond Conglerate, and Tuscarora Sandstone in New Jersey and Pennsylvania.
Abstract: Studies of the South Platte-Platte River in Colorado and Nebraska substantiate Ore9s (1964) conclusion that braided patterns in streams are created mainly by accretion of longitudinal bars and dissection of transverse bars. Distribution of bars in the South Platte-Platte River depends on texture of the bed load. Coarse, poorly sorted sediment favors formation of longitudinal bars, and finer grained, better sorted materials form transverse bars. The relative proportion of transverse to longitudinal bars increases downstream, following the river9s tendency to fractionate its load into finer sizes downstream. This is accompanied by an increase in the ratio of planar cross-stratification to horizontal stratification and a decrease in cross-channel topographic relief expressed as a bed-relief index. Relative abundances of planar cross-stratification and horizontal stratification, as well as bed-relief indices were measured in sandstones and conglomerates of the Lower Silurian Shawangunk Conglomerate, Green Pond Conglomerate, and Tuscarora Sandstone in New Jersey and Pennsylvania. These formations display downslope trends similar to those of the South Platte and Platte Rivers, and, combined with paleocurrent, grain-size distribution, and other data, suggest that the coarse eastern facies (Green Pond, Shawangunk) represent proximal braided stream deposits with longitudinal bars that grade westward and northwestward into finer grained distal braided stream sediments (Tuscarora) characterized by transverse bars.

309 citations


Cited by
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Journal ArticleDOI
TL;DR: In this article, the authors proposed a new method of analysis for fluvial facies, which subdivides fluvic deposits into local suites consisting of one or more of a set of eight basic three-dimensional architectural elements.

1,804 citations

Journal ArticleDOI
TL;DR: A review of more than sixty recent papers on modern and ancient braided-stream deposits can be found in this article, where several sedimentation models have been developed from a review of recent work.

1,755 citations

Journal ArticleDOI
01 Jun 1994-Catena
TL;DR: In this paper, a classification system for natural rivers is presented in which a morphological arrangement of stream characteristics is organized into relatively homogeneous stream types, and morphologically similar stream reaches are divided into 7 major stream type categories that differ in entrenchment, gradient, width/depth ratio, and sinuosity in various landforms.
Abstract: A classification system for natural rivers is presented in which a morphological arrangement of stream characteristics is organized into relatively homogeneous stream types. This paper describes morphologically similar stream reaches that are divided into 7 major stream type categories that differ in entrenchment, gradient, width/depth ratio, and sinuosity in various landforms. Within each major category are six additional types delineated by dominate channel materials from bedrock to silt/clay along a continuum of gradient ranges. Recent stream type data used to further define classification interrelationships were derived from 450 rivers throughout the U.S, Canada, and New Zealand. Data used in the development of this classification involved a great diversity of hydro-physiographic/geomorphic provinces from small to large rivers and in catchments from headwater streams in the mountains to the coastal plains. A stream hierarchical inventory system is presented which utilizes the stream classification system. Examples for use of this stream classification system for engineering, fish habitat enhancement, restoration and water resource management applications are presented. Specific examples of these applications include hydraulic geometry relations, sediment supply/availability, fish habitat structure evaluation, flow resistance, critical shear stress estimates, shear stress/velocity relations, streambank erodibility potential, management interpretations, sequences of morphological evolution, and river restoration principles.

1,642 citations

Journal ArticleDOI
TL;DR: This work has identified the key response variables within a lake that act as indicators of the effects of climate change on both the lake and the catchment, which reflect a wide range of physical, chemical, and biological responses to climate.
Abstract: While there is a general sense that lakes can act as sentinels of climate change, their efficacy has not been thoroughly analyzed. We identified the key response variables within a lake that act as indicators of the effects of climate change on both the lake and the catchment. These variables reflect a wide range of physical, chemical, and biological responses to climate. However, the efficacy of the different indicators is affected by regional response to climate change, characteristics of the catchment, and lake mixing regimes. Thus, particular indicators or combinations of indicators are more effective for different lake types and geographic regions. The extraction of climate signals can be further complicated by the influence of other environmental changes, such as eutrophication or acidification, and the equivalent reverse phenomena, in addition to other land-use influences. In many cases, however, confounding factors can be addressed through analytical tools such as detrending or filtering. Lakes are effective sentinels for climate change because they are sensitive to climate, respond rapidly to change, and integrate information about changes in the catchment.

1,353 citations

Journal ArticleDOI
TL;DR: In this paper, a review of the development of ideas in the fields of geomorphology/Quaternary geology vs. sedimentary geologies is provided, and key processes that operate to produce alluvial stratigraphic records over time-scales of 103−106 years.
Abstract: Summary Fluvial landforms and deposits provide one of the most readily studied Quaternary continental records, and alluvial strata represent an important component in most ancient continental interior and continental margin successions. Moreover, studies of the long-term dynamics of fluvial systems and their responses to external or ‘allogenic' controls, can play important roles in research concerning both global change and sequence-stratigraphy, as well as in studies of the dynamic interactions between tectonic activity and surface processes. These themes were energized in the final decades of the twentieth century, and may become increasingly important in the first decades of this millennium. This review paper provides a historical perspective on the development of ideas in the fields of geomorphology/Quaternary geology vs. sedimentary geology, and then summarizes key processes that operate to produce alluvial stratigraphic records over time-scales of 103−106 years. Of particular interest are changes in discharge regimes, sediment supply and sediment storage en route from source terrains to sedimentary basins, as well as changes in sea-level and the concept of accommodation. Late Quaternary stratigraphic records from the Loire (France), Mississippi (USA), Colorado (Texas, USA) and Rhine–Meuse (The Netherlands) Rivers are used to illustrate the influences of climate change on continental interior rivers, as well as the influence of interacting climate and sea-level change on continental margin systems. The paper concludes with a look forward to a bright future for studies of fluvial response to climate and sea-level change. At present, empirical field-based research on fluvial response to climate and sea-level change lags behind: (a) the global change community's understanding of the magnitude and frequency of climate and sea-level change; (b) the sequence-stratigraphic community's desire to interpret climate and, especially, sea-level change as forcing mechanisms; and (c) the modelling community's ability to generate numerical and physical models of surface processes and their stratigraphic results. A major challenge for the future is to catch up, which will require the development of more detailed and sophisticated Quaternary stratigraphic, sedimentological and geochronological frameworks in a variety of continental interior and continental margin settings. There is a particular need for studies that seek to document fluvial responses to allogenic forcing over both shorter (102−103 years) and longer (104−106 years) time-scales than has commonly been the case to date, as well as in larger river systems, from source to sink. Studies of Quaternary systems in depositional basin settings are especially critical because they can provide realistic analogues for interpretation of the pre-Quaternary rock record.

1,125 citations