An entropy based morphological variability assessment of a large braided river

Abstract

The present paper utilizes entropy to investigate variability in the surface areas of sandbars distribution of the Brahmaputra River, India. The intensity entropy disorder index (IDI) was computed for the dry and the post‐monsoon season for a selected reach of the river. The planform disorder index (PDI) was computed to represent the annual scale planform change due to seasonal flood. Finally, annual monsoon and peak flood stream power were evaluated and related to PDI. The results showed that the intensity disorder index followed a decreasing trend in dry and post‐monsoon seasons; tending towards lower deviation from a uniform distribution. It was noted that except for extreme flood years the PDI trend correlated well with monsoonal stream power. Distinctive trends in stream power were also observed in the present study. © 2018 John Wiley & Sons, Ltd.

How dynamic is the Brahmaputra? Understanding the process–form–vegetation interactions for hierarchies of energy dissipation

“…Part of the fluvial energy is also stored/absorbed within the system eventually before it initiates a new planform change (Charlton, 2007). A conceptualization of the channel instability in the Brahmaputra River basin integrating the studies of Goswami (1985), Takagi et al (2007), Karmaker et al (2017) and Chembolu and Dutta (2018) is shown in Figure 4b. After the 1950s, the extreme earthquake and series of landslides stimulated high sediment loads completely dominated the morphological processes.…”

“…In general, channel segmentation, bar erosion and migration are common morphological processes resulting in significant energy dissipation (Chembolu & Dutta, 2018;Dubey et al, 2020). It should also be noted that a considerable amount of energy in a braided river system is utilized through bedform changes and the braided belt width variability (Ashworth et al, 2000;Chembolu & Dutta, 2018).…”

“…This energy expenditure mechanism in the braided rivers shows the interdependence of the associated processes and channel form evolution (Pradhan, Chembolu, Dutta, & Bharti, 2021; Simon, 1992). In general, channel segmentation, bar erosion and migration are common morphological processes resulting in significant energy dissipation (Chembolu & Dutta, 2018; Dubey et al, 2020). It should also be noted that a considerable amount of energy in a braided river system is utilized through bedform changes and the braided belt width variability (Ashworth et al, 2000; Chembolu & Dutta, 2018).…”

“…The Brahmaputra is a classic example of a large sand‐bed braided river system (Coleman, 1969; Mosselman et al, 1995; Thorne et al, 1993), where the seasonal morphological changes are frequent due to large variability of the processes (flow and sediment transport) and geological factors (bed slope, nodal points, braided belt width and high erodible banks) (Chembolu & Dutta, 2018; Goswami, 1985; Karmaker & Dutta, 2011, 2013, 2015; Singh et al, 2004). Such extreme non‐uniform nature of process–form interactions has enabled the river system to dissipate the fluvial energy at different scales.…”

“…and geological factors (bed slope, nodal points, braided belt width and high erodible banks) (Chembolu & Dutta, 2018;Goswami, 1985;Karmaker & Dutta, 2011, 2015Singh et al, 2004). Such extreme non-uniform nature of process-form interactions has enabled the river system to dissipate the fluvial energy at different scales.…”