Changes In Sinuosity Research Articles

Evolution of sub-ice-shelf channels reveals changes in ocean-driven melt in West Antarctica

Abstract Basal channels, which are troughs carved into the undersides of ice shelves by buoyant plumes of water, are modulators of ice-shelf basal melt and structural stability. In this study, we track the evolution of 12 large basal channels beneath ice shelves of the Amundsen and Bellingshausen seas region in West Antarctica using the Landsat record since its start in the 1970s through 2020. We observe examples of channel growth, interactions with ice-shelf features, and systematic changes in sinuosity that give insight into the life cycles of basal channels. We use the last two decades of the record, combined with contemporary ice-flow velocity datasets, to separate channel-path evolution into components related to advection by ice flow and those controlled by other forcings, such as ocean melt or surface accumulation. Our results show that ice-flow-independent lateral channel migration is overwhelmingly to the left when viewed down-flow, suggesting that it is dominated by Coriolis-influenced ocean melt. By applying a model of channel-path evolution dominantly controlled by ice flow and ocean melt, we show that the majority of channels surveyed exhibit non-steady behavior that serves as a novel proxy for increased ocean forcing in West Antarctica starting at least in the early 1970s.

Quantifying the Impact of Changes in Sinuosity on River Ecosystems

To quantitatively study the hydrodynamic changes in different river morphologies and clarify the impact of morphological changes on river ecosystems, this study examined a section of the Nansha River near Laoniuwan in the Haidian District, Beijing, and characterized different river morphologies by river sinuosity. The River 2D model was used for simulation and analysis, and the depth and velocity diversity indices were introduced to quantify the distribution of depth and velocity under different sinuosities. Cyprinus carpio was selected as the target fish in this study, and its suitability curve was determined using literature and field surveys. Combined with the simulation results, a weighted usable area curve was established to identify its inflection point and maximum value and determine the ecological flow in the river under different sinuosities, that is, to clarify the relationship between sinuosity and ecological flow. The results showed that the lower the sinuosity, the worse the depth and velocity diversity, but a greater sinuosity did not lead to better depth and velocity diversity. The depth and velocity diversity of a sinuosity of 1.5 were better than those of 1.89 in general, except for low flow conditions (Q = 5 m3/s). For rivers with water use restricted by nature and society and where ecological needs exist, ecological engineering that appropriately changes the planform of rivers can be considered to increase the diversity of river/channel geometry and provide a basis for the ecological restoration of rivers.

Exploring Geomorphic Features in Lower Sabarmati River Basin as Signatures of Palaeoenvironmental Change, Gujarat: A Remote Sensing Approach

Abstract The aim of this work is to unravel the role of geomorphic indicators and/or signatures to be used as evidence for palaeo-environmental changes and other forcing mechanisms from the lower reaches of the Sabarmati river basin, Gujarat, India region. In the present study, geomorphic features have been used as archives to debate the past land-sea interactions using satellite imagery. In the lower reaches of the Sabarmati river, a number of meanders, sinuosity changes, palaeochannels, and scroll plains have been identified. As a result of the rise and fall of the sea during the Holocene period, the changes in hydrodynamic and steady-state conditions of the river can be visualized in terms of changes in landforms. Thus, the intriguing geomorphic landforms in the lower portions of the Sabarmati basin delineate the likely archives and signs of previous environmental change, in particularly ~ the relative sea level change. This approach provides first-hand documentation of the fluvial evolution under the direct impact of the varying forcing mechanisms. This attempt shows the effectiveness of satellite images in unravelling the clues to past changes from the landscape in a fast and insightful manner.

Big Pine Creek Ditch revisited: Planform recovery to channelization and the timescale of river meandering

Channelization has changed the form and dynamics of rivers on a global scale. In the midwestern United States, widespread straightening of meandering headwater streams has been undertaken for the purpose of improving land drainage. Few studies have examined in detail how meandering streams respond to straightening, especially over timescales of nearly a century following straightening. This study uses historical aerial imagery and contemporary lidar data to examine how a small headwater stream that was straightened nearly a century ago, Big Pine Creek Ditch (BPCD) in Indiana, USA, has adjusted to straightening and to relate observed changes to stream power. The evolution of this fluvial system was examined in the late 1970s and this study updates that previous work using additional imagery and GIS-based methods, extending the timeline of analysis from 1932 to 2018. Results reveal that recovery varies spatially along the length of BPCD with some reaches not adjusting at all, some reaches increasing in sinuosity but then being artificially restraightened, and other reaches evolving continuously in response to channelization. For reaches that have evolved continuously, the rate of increase in sinuosity over time is directly related to bankfull stream power per unit length. Rates of increase in sinuosity per logarithmic unit of power per unit length have been linear and should attain the prechannelized relation between sinuosity and stream power over a timescale of about 100 years. Reaches with estimated bankfull stream power per unit area below 25 W m−2 exhibit no recovery of sinuosity, whereas those with power per unit area greater than 50 W m−2 have progressively increased in sinuosity. Between these thresholds, straightened reaches may or may not increase in sinuosity. Not all aspects of channel planform recovery are captured by changes in sinuosity; the prechannelized meandering stream exhibited greater lateral shifts in the position of the meander belt than do current meandering reaches. Overall, the study provides insight into spatial and temporal variability of recovery to channelization, the long-term recovery of meandering streams to straightening, as well as the timescale of meander development in straight channels.

Sinuosity of Atmospheric Circulation over Southeastern China and Its Relationship to Surface Air Temperature and High Temperature Extremes

Linking sinuosity, a fairly recently developed metric, with high temperature extremes (HTEs) can be both useful and insightful to better understand the physical mechanisms behind HTEs. However, it is not clear whether there exists a relationship between the sinuosity changes and HTE changes in present and future climate conditions over southeastern China. In this paper, the anomalous characteristics of the atmospheric circulation are quantified by sinuosity. Three sinuosity metrics are used in this study: individual sinuosity (SIN), aggregate sinuosity (ASIN), and comprehensive sinuosity (CSIN). Furthermore, we examine the relationship between sinuosity changes and HTE changes in present and future climate conditions. ASIN is strongly correlated with surface air temperature (SAT). We find that the influence of individual sinuosity (SIN) at different latitudes on the SAT of southeastern China is different. The SIN of low (middle) latitude isohypses has significant positive (negative) correlations with the SAT of southeastern China. The SIN of high-latitude isohypses is rather limited and can therefore be ignored. The projected relationship between the sinuosity changes and HTE changes in the late 21st century suggests similar results. The change in SAT is related to the changes in climate variables over southeastern China in the future, and these changes increase with the increase in Z500 or V850 and the decrease in U500. Moreover, the frequencies of large (small) comprehensive sinuosity (CSIN) values at low (mid) latitudes will increase. At the end of the 21st century, Z500 isohypses at different latitudes will have an obvious poleward shift. Our results indicate that measuring the aggregate waviness of the midtropospheric flow (via sinuosity) can provide insight regarding HTEs, and the climate model output can be used to examine the future likelihood of increased HTE.

New models for submarine channel deposits on structurally complex slopes: Examples from the Niger delta system

Submarine channel complexes are often described as having a two-phase stratigraphic evolution where an initial phase of migration is followed by aggradation, generating a ‘hockey-stick shaped’ channel trajectory. However, the role of tectonic forcing in modifying time-integrated sedimentary architectures remains poorly understood. Here, we evaluate how tectonically driven changes in slope modify the evolution—both in terms of morphology and stratigraphic architecture—of submarine channels across a range of spatial scales from the fundamental architectural unit, a channel element, to the scale of a channel complex set, using examples from the Niger Delta system. From a 3D, time-migrated seismic reflection volume, we use amplitude extractions, frequency decomposition and RGB blending to determine channel stratigraphic architectures. These observations are used systematically to evaluate the development of cross-sectional and planform architectures as the channel systems interact with a range of active and pre-existing structural bathymetry. Our results indicate that while a channel complex's stratigraphic architecture may be captured by a two-phase evolution on unstructured slopes, this model fails on structurally complex slopes. Unstructured slope channel complexes display a repeated arrangement of migration dominating the early stratigraphic record and subsequent aggradation. The late aggradational phase signals a decrease in the rate of growth in channel complex width and the rate of change in sinuosity relative to aggradation throughout the complex's development. However, tectonically driven changes in sinuosity and the relative rates of channel migration and aggradation modify complex development significantly. We identify three end-member styles of channel-structure interaction, determined by the timing of bathymetry development and its associated style: (1) pre-channel structural bathymetry; (2) coeval positive relief, and (3) coeval negative relief. Where structural relief pre-dates channel inception, a principal adjustment is in the initial channel course with early channel elements being forced around positive relief of the structure, generating long-wavelength bends in the complex's course. Where structure continues to modify slope creating positive and negative bathymetry during complex development, migration and bend development continue with complex width and channel element sinuosity increasing until abandonment. These observations demonstrate that submarine channel architecture and planform are highly sensitive to tectonic perturbation and we use these results to generate graphical models that show predicted architectural evolution of submarine channels on structurally complex slopes in general.

Planform Dynamics of Kankai River using GIS and Remote Sensing

The Kankai river is a rainfed perennial river of eastern Nepal and carries a large quantum of silt, and enters in Kishanganj of West Bengal, India. Recently, a bridge collapsed in a village in the Kishanganj district due to a rise in the water levels of the Kankai river. This paper presents a study of the dynamics of changes in channel planform and measurement of the erosion and accretion of the Kankai river in Bihar, India from 2000 to 2018. Spatial data were processed in GIS to determine the changes in sinuosity, centreline migration rates, and extent of erosion, and deposition of sediment. The maximum river shift was obtained as 800 to 1600 m and the minimum river shift varied from 6 to 70 m. With a sinuosity ratio for the whole reach of the river of 1.45, the Kankai river is considered a sinuous river and needs river training works at the erosion sites.

Patterns in river channel sinuosity of the Meuse, Roer and Rhine rivers in the Lower Rhine Embayment rift-system, are they tectonically forced?

The tectonic and fluvial setting of the Rhine-Meuse river system in the Lower Rhine Embayment rift system is exceptionally well known. The 19th century, pre-regulation river courses of three rivers are used to study a postulated sinuosity response to faulting. The fault-perpendicular Meuse River shows patterns of sinuosity changes at different spatial scales. The large-scale (>5 km) sinuosity changes are related mainly to the faulting-induced changes of the subsurface lithology, determining the bed and bank characteristics. However, at a smaller scale, some fault-related channel sinuosity anomalies are observed. The fault-parallel Roer River shows sinuosity changes related to a normal, non-tectonic longitudinal gradient change. Sinuosity patterns of the Rhine River are predominantly related to lithological differences and reduced incision rates. Sinuosity can thus be an indicator of tectonic motions, but gradient, subsurface lithology and river bank composition determine sinuosity as well. Therefore, a sinuosity change is no proof for fault activity. On the other hand, the absence of a sinuosity change does not imply inactivity of a fault at geological time-scales.

Channel planform dynamics of lower Ramganga River, Ganga basin, GIS and remote sensing analyses

Ramganga River is characterized by frequent planform changes in its lower reaches. The plain topography and frequent floods occurrence are powerful agents to change the river morphology. This paper presents a detailed account of channel planform dynamics of River from 1780 to 2017. Spatial data were analyzed in GIS to determine changes in sinuosity, centerline migration rates and large-scale dynamics of the River. The results revealed its overall shifting towards south-west direction. In upstream, planform repeatedly oscillated in its floodplain. In the downstream, a highly stable reach is found which does not show any significant shifting character in last 50 years, but a major avulsion of 11 km is found in its confluence with the Ganges. The study provides recent and reliable information on the channel planform dynamics and will help as a decision support tool for designing and implementation of drainage development works.

Influence of neotectonism on geomorphology and depositional architecture of the Gandak megafan, middle Ganga plain, India

The Gandak megafan formed by episodic tilting of tectonic block followed by an eastward shift of the Gandak River. The study area has been identified with 5 distinct depositional units, which were chronologically named as oldest Gandak plain (OSGP), old Gandak plain (OLGP), Gandak terminal fan (GTFn)-I, -II and -III. An integrated approach including morphometry, pedology, GPR study and OSL dating was adopted to study morphotectonics of the megafan. DEM of the megafan and anomalies in drainage of the area helped to delineate NE-SW trending normal faults, which divide the megafan block into 3 tectonic sub-blocks. Present-day channels reciprocate the fault movements through anomalies in drainage and change in sinuosity around the faults. Sinuosity of the Gandak, Chhoti Gandak and other small streams (Daha, Gandaki and Rohini) varies from 1.6, 4.5 and 3.5, respectively, which suddenly increases across faults. The concurred variations in longitudinal river profiles and SL index appear to be attributable to the tectonic controls. The development of these faults and subsequent tilting of the sub-blocks influenced the sedimentary architecture and fluvial geomorphology of the megafan. A linear arrangement of natural waterlogs and paleochannels observed in satellite images imply lateral shifting of the Gandak River. Older depositional units, OSGP and OLGP, show well-developed thick solum formation (~2.2 m and 1.9 m, respectively). Comparatively, the younger units i.e. terminal fans show poor to no development of soil with ~1.2 m to 0.8 m thick successions. OSL dates indicate that older and younger units were deposited between ~10.7 and 8.5 Ka, and ~5.7 and 1.4 Ka, respectively. The tectonically stable period of ~3 Ka is also exhibited by non-depositional surfaces in soil successions.

Sinuosity evolution along an incising channel: New insights from the Jordan River response to the Dead Sea level fall

AbstractThe geomorphic evolution of the Jordan River in recent decades indicates that interaction between incision and high‐magnitude floods controls sinuosity changes under increasing mouth gradients during base‐level fall. The evolution of the river was analyzed based on digital elevation models, remotely sensed imagery, hydrometric data, and a hydraulic model. The response varies along the river. Near the river mouth, where incision rate is high and a deep channel forms, overbank flooding is less likely. There, large floods exert high shear stress within the confined channel, increasing sinuosity. Upstream, near the migrating knickzone channel gradients also increase, incision is more moderate and floods continue to overtop the banks, favoring meander chute cutoffs. The resulting channel has a downstream well‐confined meandering segment and an upstream low‐sinuosity segment. These new insights regarding spatial differences along an incising channel can improve interpretations of the evolution of ancient planforms and floodplains that responded to base‐level decline. © 2018 John Wiley & Sons, Ltd.

Geomorphology and evolution of the late Pleistocene to Holocene fluvial system in the south-eastern Llanos de Moxos, Bolivian Amazon

In the Bolivian Amazon several paleochannel generations are preserved. Their wide spectrum of morphologies clearly provides crucial information on the type and magnitude of geomorphic and hydrological changes within the drainage network of the Andean foreland. Therefore, in this study we mapped geomorphological characteristics of paleochannels, and applied radiocarbon and optically stimulated luminescence dating. Seven paleochannel generations are identified. Significant changes in sinuosity, channel widths and river pattern are observed for the successive paleochannel generations. Our results clearly reflect at least three different geomorphic and hydrological periods in the evolution of the fluvial system since the late Pleistocene. Changes in discharge and sediment load may be controlled by combinations of two interrelated mechanisms: (i) spatial changes and re-organizations of the drainage network in the upper catchment, and/or (ii) climate changes with their associated local to catchment-scale modifications in vegetation cover, and changes in discharge, inundation frequencies and magnitudes, which have likely affected the evolution of the fluvial system in the Llanos de Moxos. In summary, our study has revealed the enormous potential which geomorphic mapping and analysis combined with luminescence based chronologies hold for the reconstruction of the late Pleistocene to recent fluvial system in a large portion of Amazonia.

Geomorphological evidence of recent tilting in the Central Amazonia Region

Geomorphometric techniques applied to remote sensing data represent powerful tools as an aid for detecting terrain features produced by recent vertical crustal movements in a variety of landscapes. In this work, geomorphometric analysis of the Central Amazonia drainage network using Shuttle Radar Topography Mission (SRTM) data was carried out to determine surface water loading and tectonic influence on the development of the Uatumã and Urubu river basins since the Miocene. The main objective was to detect geomorphological domains of lateral stream migration and channel sinuosity changes that could indicate recent vertical crustal movement. To achieve this, the Transverse Topographic Symmetry Factor and Sinuosity Index were applied to analyze the study area drainage network. Comparison of the geomorphological domains with structural field data and records of seismicity suggests that they are influenced by subsurface fault reactivation, which coincides in space with faults mapped in outcrops that have activated since the Miocene. This interpretation is corroborated by the spatial correspondence between these faults with domain boundaries and shapes, by river sinuosity change when crossing these boundaries, and by a high concentration of seismic activity along one of these limits. The crustal movement caused by hydrological loading can also influence such geomorphological features. Such is the case of lateral stream migrations of a domain in the opposite sense to the Amazon River flow. This may be a consequence of the more pronounced expression of hydrological loading in the Negro and Solimões river confluence region.

Stem Sinuosity Changes in Young and Merchantable Stands of Pinus taeda

Abstract A survey of stem sinuosity severity and occurrence was conducted on six sites in North Carolina and South Carolina (USA) in Pinus taeda stands approximately 2 years after establishment. Approximately 1,400 trees on each site were measured for height, diameter, and degree of sinuosity in the stem at the beginning of the growing season and again after the completion of the growing season. Fifty-two percent of the trees increased in sinuosity over the growing season. Using stand records and observations by local foresters, two mature stands of loblolly pine (Pinus taeda) were located in the Atlantic Coastal Plain, where excessive stem sinuosity was reported to be present at ages 1 to 3 years. Seven trees were felled from each site. The 2.4-m butt logs were removed from each tree along with a 0.61-m bolt from the remaining felled tree. Slices were then cut through the log progressing through the pith. A single veneer containing the pith from each log was then selected for calculation of log volume, juvenile wood volume, and the volume of sinuous growth. Seven trees at the two sites were found to have had severe sinuosity earlier in their lives. Of the seven sinuous trees, three trees took only 1 year to correct the sinuous growth and return to a normal growth pattern. Two trees took an additional year to return to cylindrical growth, one tree returned to normal growth after the third year, and a single tree returned to a straight appearance by the end of the fifth year after the initiation of sinuous growth. Therefore, the sinuous portions of all seven trees were entirely contained within the juvenile core of the tree. Clear static bending specimens were machined and tested. Trees that were found to be nonsinuous produced mature wood that was significantly stiffer than the sinuous trees.

A systematic overview of the coincidences of river sinuosity changes and tectonically active structures in the Pannonian Basin

As tectonic movements change the valley slope (low-gradient reaches of valleys, in sedimentary basins), the alluvial rivers, as sensitive indicators, respond to these changes, by varying their courses to accommodate this forcing. In our study sinuosity values, a commonly used characteristic parameter to detect river pattern changes, were studied for the major rivers in the Pannonian Basin in order to reveal neotectonic influence on their planform shape.Our study area comprises the entire Pannonian Basin (330,000km2) located in eastern Central-Europe, bounded by the Alps, Carpathians and Dinarides. The studied rivers were mostly in their natural meandering state before the main river regulations of the 19th century. The last quasi-natural, non-regulated river planforms were surveyed somewhat earlier, during the Second Military Survey of the Habsburg Empire. Using the digitized river sections of that survey, the sinuosities of the rivers were calculated with different sample section sizes ranging from 5km to 80km. Depending on the bank-full discharge, also a ‘most representative’ section size is given, which can be connected to the neotectonic activity.In total, the meandering reaches of 28 rivers were studied; their combined length is 7406km. The places where the river sinuosity changed were compared to the structural lines of the “Atlas of the present-day geodynamics of the Pannonian Basin” (Horváth et al., 2006). 36 junctions along 26 structural lines were identified where the fault lines of this neotectonic map crossed the rivers. Across these points the mean sinuosity changed. Depending on the direction of the relative vertical movements, the sinuosity values increased or decreased. There were some points, where the sinuosity changed in an opposite way. Along these sections, the rivers belong to the range of unorganized meandering or there are lithological margins.Assuming that the rivers indicate on-going faulting accurately, some places were found, where positioning of the faults of the neotectonic map could be improved according to the sinuosity jumps. However, some significant sinuosity changes cannot be correlated to known faults. In these cases other factors may play a role (e.g., hydrological changes, increase of sediment discharge also can modify sinuosity). In order to clarify the origin of these changes seismic sections and other geodynamical information should be analyzed to prove or disprove tectonic relationship if hydrological reasons can be excluded.

Evaluating Recent Stream Channel and Pattern Changes for Stream Resource Protection and Restoration: An Example from West-central Ohio

Recent changes in stream channel and pattern morphology, hydrology, and channel and floodplain stratigraphy of nine streams in west-central Ohio are evaluated as part of a data-gathering phase of a stream resource protection plan. The study reaches represent the variation in external and internal drainage basin variables that likely control differences in channel hydrology in the county, including watershed area, underlying geology, and land use. A longitudinal profile and 6–8 cross sections were surveyed for each reach; particle sizes were measured and bank stratigraphy was described at each cross section. Former channel positions were delineated from georeferenced aerial photographs from the period 1938 to 2002. Currently most streams are moderately to slightly entrenched into their basal channel gravels and the underlying till, outwash, or bedrock. Entrenchment is likely the result of channel straightening, mostly after 1938, but may also be due to reduced sediment yield resulting from improved soil conservation practices or urbanization. The physiographic floodplain is no longer accessible by more frequent flood events (RI < 5 yr), but active point bars and unit bars confined within the entrenched channels are redefining bankfull conditions and incipient meander migration is developing a new floodplain. Changes in sinuosity, radius of curvature, and meander wavelength between 1938 and 2002 along less-actively managed streams indicate the reaches are moving toward equilibrium relationships between bankfull channel and meander properties. A first approximation of the space in which the equilibrium pattern will develop is provided by the equilibrium relation between bankfull channel width and channel belt width.

Complexity, self-organisation and variation in behaviour in meandering rivers

River meanders are natural features on the surface of Earth that present some degree of regularity of form. They range from being highly dynamic to being stable under present conditions. Conventional theory is that meanders develop to an equilibrium form which is related to discharge and sediment load. Other research has demonstrated that many highly active meanders exhibit a continuous evolution over time and a non-linearity in rate of development. Ideas of autogenesis and of self-organised criticality as being an explanation of some meander changes have been proposed. In this paper data from rivers around the world are examined for further evidence of autogenic, self-organised or non-linear behaviour through analysis of change in sinuosity over time for reaches and change in individual bend form, particularly bend curvature and bend elongation. Some examples do exhibit trends of increasing sinuosity over time and a few show limits from which large decreases occur. Several case studies show non-linearity of behaviour and increasing complexity of form. Other case studies, however, do not exhibit such trends. Phase space plots are used to help uncover emergent behaviour but show a variety of patterns. The example of a reach in which multiple cut-offs occurred is analysed for mechanisms of self-organisation of the planform and in the pool-riffle pattern. Riffles are more closely spaced and also more transient in the more rapidly changing and higher sinuosity parts of the channel. Hypothetical trajectories of different meander behaviour, including for bedrock meanders, are plotted but the challenge remains to uncover the conditions for occurrence and for divergence of tendencies to stability and instability. Identification of attractors and phase space of behaviour of different meandering systems offer the potential for application to sustainable channel management.

Controls on channel sinuosity changes: a case study of the Tisza River, the Great Hungarian Plain

The planform geometry of the Tisza, the trunk river of the subsiding Great Hungarian Plain is studied by reconstruction of the last pre-regulation river course. The thalweg sinuosity has been computed for the main alluvial section of the river. Remarkable sinuosity changes have been found to correlate with discharge and sediment load changes at the inflow of tributaries, as well as with active deformation areas, like differential subsidence and wrench fault zones. Analysing the change of the river pattern, a new discrimination line has been derived, which separates the meandering zone on the classic slope vs. discharge diagram into two subzones. The first subzone (lower slope values) corresponds to a range of true, self-organized meandering. The second subzone (higher slope values) corresponds to a range of ‘unorganized meandering’. This is a range where river sinuosity decreases although the channel slope increases. In the case of the Tisza River, this subzone equals to the wandering river pattern.

Locational Probability for a Dammed, Urbanizing Stream: Salt River, Arizona, USA.

/ Data from historical aerial photographs analyzed with a GIS show that river channel change on the Salt River in the Phoenix metropolitan area of central Arizona has been driven by large-scale regional flood events and local human activities. Mapping of functional surfaces such as low-flow channels, high-flow channels, islands, bars attached to channel banks, and engineered surfaces shows that during the period from 1935 to 1997, the relative areal coverage of these surfaces has changed. Flood events have caused general changes in sinuosity of the low-flow channel, but islands have remained remarkably consistent in location and size, while channel-side bars have waxed and waned. The most important determinant of local channel form and process is sand and gravel mining, which in some reaches occupies more than 70% of the active channel area. The general location of mining is closely related to the location of the moving urban fringe, which serves as a market for sand and gravel during construction. Quantitative spatial analysis of imagery supplemented by field mapping shows that for each location within the general channel area, it is possible to specify a probability of encountering a low-flow channel or other fluvial features. Maps showing the distribution of these probabilities of occurrence reveal the most probable location and configuration of the channel as it occurred in the past. Some reaches have the low-flow channel located persistently within a limited area as a result of bedrock or sinuosity controls, but other reaches dominated by flow separation or shallow gradient have almost no persistence in channel location from one flood to another.

Active tilting of the United States midcontinent: Geodetic and geomorphic evidence

In the midcontinent there is a remarkable correlation between the tilt rates measured by geodetic releveling and the downstream change in sinuosity of adjacent rivers. The correlation indicates that measured tilts with rates reaching 10−7 rad yr−1 and that extend for 15 to 50 km represent real crustal movements and not errors or near-surface effects. The tilting has probably continued for less than 1,500 yr and may involve oscillatory movements of crustal blocks.