Formation of paleovalleys in the Central Himalaya during valley aggradation

Reconstruction of Late Quaternary climate and seismicity using fluvial landforms in Pindar River valley, Central Himalaya, Uttarakhand, India

“…The hill slope processes and bedrock incision magnitudes in the fluvial system are intimately associated with the spatial and temporal changes in the climatically and tectonically governed base level changes (Burbank et al, 1996;Alley et al, 2003). One of the consequences of the sensitive erosion and transport regime is that two broad categories of landforms of the main valleys can be classified as the aggradation landforms (valleyfill) and the degradation landforms (strath terraces) (Chaudhary et al, 2015). The aggradation landform in Himalaya receives sediment from two major sources notably paraglacial sediment released as the result of deglaciation (Church and Slaymaker, 1989;Schildgen et al, 2002) and slope wash/landslide generated colluvium, freshly generated under post glacial climate circumstances (Juyal et al, 2010;Chaudhary et al, 2015).…”

“…One of the consequences of the sensitive erosion and transport regime is that two broad categories of landforms of the main valleys can be classified as the aggradation landforms (valleyfill) and the degradation landforms (strath terraces) (Chaudhary et al, 2015). The aggradation landform in Himalaya receives sediment from two major sources notably paraglacial sediment released as the result of deglaciation (Church and Slaymaker, 1989;Schildgen et al, 2002) and slope wash/landslide generated colluvium, freshly generated under post glacial climate circumstances (Juyal et al, 2010;Chaudhary et al, 2015). It is observed that during periods of abnormal monsoon, the above sediment sources becomes active (Bookhagen et al, 2005) as a result the sediments temporary overwhelms the fluvial system's transport capability which eventually leads to the aggradation (Pratt-Sitaula et al, 2002;Chaudhary et al, 2015).…”

“…The aggradation landform in Himalaya receives sediment from two major sources notably paraglacial sediment released as the result of deglaciation (Church and Slaymaker, 1989;Schildgen et al, 2002) and slope wash/landslide generated colluvium, freshly generated under post glacial climate circumstances (Juyal et al, 2010;Chaudhary et al, 2015). It is observed that during periods of abnormal monsoon, the above sediment sources becomes active (Bookhagen et al, 2005) as a result the sediments temporary overwhelms the fluvial system's transport capability which eventually leads to the aggradation (Pratt-Sitaula et al, 2002;Chaudhary et al, 2015). Once the river becomes transport limited due to decrease in the discharge (weak monsoon in case of the Central Himalaya), the river began to incise its own sediment in order to attain the pre-aggradation base level (Juyal et al, 2010 and reference therein).…”

“…However, catchment scale studies on fluvial response to monsoon variability are limited Juyal et al, 2010;Ray and Srivastava, 2010;Shukla et al, 2010;Chaudhary et al, 2015). Further the surface uplift/erosion rate using in situ produced, cosmogenic radio-nuclide studies indicate that in the Alaknanda River catchment, the basin wide uplift/ erosion rate varies~1.2 mm/year on the southern margin of Tibetan Plateau,~2.7 mm/year in Higher Himalaya and <1 mm/year in the Lesser Himalaya (Vance et al, 2003).…”

Landscape evolution of Rivers in the Ganga Plain and Himalaya

“…The work suggested that transition between arid glacial and climatic optimum allowed valley aggradation and peak wetness leading to reduced sediment/water ratio and channel incision. Later, similar observation was made while understanding the formation of fossil valleys and epigenetic gorges and the non-glaciated rivers like the Ramganga (Chaudhary et al, 2015(Chaudhary et al, , 2017. Further, increased hill slope erosion and reduced channel transport capacity during drier climate is envisaged as a controlling factor behind river aggradation (Scherler et al, 2015).…”