Decadal length changes in the fluvial planform of the River Ganga: bringing a mega-river to life with Landsat archives

Gupta, Niladri; Atkinson, Peter M.; Carling, Paul A.

doi:10.1080/2150704x.2012.682658

Cited by 60 publications

(35 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This morphology is consistent with the observation that major chute cutoffs are most prevalent in rivers which, like the Ganga, are characterized by a streamwise periodicity in channel width (Federici and Paola, ). The frequency of major avulsive episodes in the Ganga may be around 30 years (Gupta et al ., ) leaving little time for hydraulic streamlining to develop before the system is further reset. Thus when interpreting differences in island shape parameters, the differences can be related to the low‐level behaviours and higher level behaviours which operate at different temporal and spatial scales in rivers.…”

Section: Discussionmentioning

confidence: 99%

Discrimination of alluvial and mixed bedrock–alluvial multichannel river networks

Meshkova

Carling

2013

Earth Surf Processes Landf

View full text Add to dashboard Cite

This paper explores the use of planview morphological metrics to quantitatively describe and distinguish mixed bedrock-alluvial multichannel networks from alluvial multichannel networks. The geometries of the channel planforms of two bedrock-constrained networks (Mekong and Orange rivers) are compared with the classic alluvial anastomosed Upper Columbia River and the wandering Ganga River. Widely recognized indices utilized include: channel link count and channel sinuosity, with additional emphasis being given to the less common metrics: network bifurcation angles and island shape characteristics (i.e. aspect ratio, compactness, roundness and convexity). Link count data, with one notable exception, conform to theoretical expectations. Bifurcation angles for all four multichannel rivers are significantly greater than angles reported for braiding rivers. Island convexity clearly discriminates the two alluvial rivers from the two bedrock-influenced rivers. The width of the macrochannel, in which each network develops, has a positive influence on the number of channel links and is further related to channel slope variations which, in turn, are influenced by terrain structure revealed using trend-surface analysis. The geometry of multichannel networks are often laterally constrained such that the values of channel bifurcation angles and link sinuosity values reduce as the network intensifies and channel links are shortened. These latter observations go some way to explain the oft-noted relatively 'straight' links seen within multichannel networks which are a necessary adjustment to space-filling constraints placed on a network.

show abstract

Section: Discussionmentioning

confidence: 99%

Discrimination of alluvial and mixed bedrock–alluvial multichannel river networks

Meshkova

Carling

2013

Earth Surf Processes Landf

View full text Add to dashboard Cite

show abstract

“…In terms of observing natural fluvial planform change, 30 m Landsat data overcome the obstacles of poor temporal resolution and limited spatial coverage, but their 32 year record is significantly shorter than the inception‐to‐cutoff time scale of most meandering rivers. Nevertheless, a growing number of studies have leveraged Landsat imagery to map and measure planform changes of major rivers [e.g., Yang et al ., ; Baki and Gan , ; Gupta et al ., ]. Rivers flowing through the tropical Amazon region have been of particular interest [ Kalliola et al ., ; Constantine et al ., ; Schwendel et al ., ] partly due to their rapidly changing planforms.…”

Section: Introductionmentioning

confidence: 99%

High spatiotemporal resolution of river planform dynamics from Landsat: The RivMAP toolbox and results from the Ucayali River

Schwenk

Khandelwal

Fratkin

et al. 2017

Earth and Space Science

140

121

View full text Add to dashboard Cite

Quantifying planform changes of large and actively migrating rivers such as those in the tropical Amazon at multidecadal time scales, over large spatial domains, and with high spatiotemporal frequency is essential for advancing river morphodynamic theory, identifying controls on migration, and understanding the roles of climate and human influences on planform adjustments. This paper addresses the challenges of quantifying river planform changes from annual channel masks derived from Landsat imagery and introduces a set of efficient methods to map and measure changes in channel widths, the locations and rates of migration, accretion and erosion, and the space-time characteristics of cutoff dynamics. The techniques are assembled in a comprehensive MATLAB toolbox called RivMAP (River Morphodynamics from Analysis of Planforms), which is applied to over 1500 km of the actively migrating and predominately meandering Ucayali River in Peru from 1985 to 2015. We find multiscale spatial and temporal variability around multidecadal trends in migration rates, erosion and accretion, and channel widths revealing a river dynamically adjusting to sediment and water fluxes. Confounding factors controlling planform morphodynamics including local inputs of sediment, cutoffs, and climate are parsed through the high temporal analysis.

show abstract

“…Güneralp and Rhoads (2009;2010) [34,35], for example, also performed a similar type of river planform-change analysis, but employed aerial photography. In contrast, the MCC application proposed in the present study automatically generates directional landscape changes; no manual digitization step is utilized or required, even though manual digitization of river planforms is common practice (e.g., [36]). Yang et al (2015) [37] determined river-channel migration, or shift, direction, based on sequential satellite images; however, this shifting direction focuses on the migration of the centerline and is only comprised of a "left" or "right" designation.…”

Section: Land-change Analysismentioning

confidence: 94%

What is the Direction of Land Change? A New Approach to Land-Change Analysis

et al. 2017

View full text Add to dashboard Cite

Accurate characterization of the direction of land change is a neglected aspect of land dynamics. Knowledge on direction of historical land change can be useful information when understanding relative influence of different land-change drivers is of interest. In this study, we present a novel perspective on land-change analysis by focusing on directionality of change. To this end, we employed Maximum Cross-Correlation (MCC) approach to estimate the directional change in land cover in a dynamic river floodplain environment using Landsat 5 Thematic Mapper (TM) images. This approach has previously been used for detecting and measuring fluid and ice motions but not to study directional changes in land cover. We applied the MCC approach on land-cover class membership layers derived from fuzzy remote-sensing image classification. We tested the sensitivity of the resulting displacement vectors to three user-defined parameters-template size, search window size, and a threshold parameter to determine valid (non-noisy) displacement vectors-that directly affect the generation of change, or displacement, vectors; this has not previously been thoroughly investigated in any application domain. The results demonstrate that it is possible to quantitatively measure the rate of directional change in land cover in this floodplain environment using this particular approach. Sensitivity analyses indicate that template size and MCC threshold parameter are more influential on the displacement vectors than search window size. The results vary by land-cover class, suggesting that spatial configuration of land-cover classes should be taken into consideration in the implementation of the method.

show abstract

Decadal length changes in the fluvial planform of the River Ganga: bringing a mega-river to life with Landsat archives

Cited by 60 publications

References 22 publications

Discrimination of alluvial and mixed bedrock–alluvial multichannel river networks

Discrimination of alluvial and mixed bedrock–alluvial multichannel river networks

High spatiotemporal resolution of river planform dynamics from Landsat: The RivMAP toolbox and results from the Ucayali River

What is the Direction of Land Change? A New Approach to Land-Change Analysis

Contact Info

Product

Resources

About