Assessing Sediment Pulse during an Extreme Hydrological Event in the Alaknanda Basin, Northwestern Himalaya, India

Abstract

In the year 2013, the Northwestern Himalaya witnessed an extreme hydrological event that severely affected the upper Ganga Basin. The unexpected high sediment mobilisation in the basin affected the human population, infrastructure, and ecology in several reaches of the Ganga river and its tributaries. In an exceedingly affected reach, the Kedarnath valley, a considerable sediment volume (~ 26243 x 104 m3) was mobilised during the 2013 extreme hydrological event. In the Srinagar valley, up to 50 x 104 m3 of legacy sediment was washed away during the same event. This sediment mobilisation generated sediment pulses in the affected region, which is assessed through remote sensing, field observations and existing literature, in the Kedarnath and Srinagar valleys. Results show that the evolution of translative, dispersive, and their combined sediment pulse pattern in both selected reaches of the upper Ganga Basin. The mountainous region of the upper Ganga basin has very few monitoring stations observing sediment movement, and data from such stations are mostly unavailable due to which our understanding of the sediment movement in the Himalaya remains very poor. Therefore, it is suggested that there is a need for detailed studies of the sediment transport mechanism in the Himalayan river basins especially during such extreme hydrological events when large volume of sediment is mobilised.

Characterization and assessment of flood inundated areas of lower Brahmaputra River Basin using multitemporal Synthetic Aperture Radar data: A case study from NE India

“…The generated temporal flood inundation, BRCA, BRSBA, and BRCW data will help the disaster management agencies, policymakers, and government agencies assess and mitigate future flooding. The experience from the present study would also benefit urgent response to sediment-related disasters like sediment pulse (Devrani, Singh, Mehta, & Ramanathan, 2021). The launch of GEE has opened new aspects for the remote sensing community, but this tool has not been extensively used for flood hazard mapping (Tamiminia et al, 2020).…”

Assessment of Active Ground Subsidence in the Dibrugarh and Digboi Areas of Assam, Northeast India, Using the PSInSAR Technique

“…In terms of the seismo-tectonics, geology, and geomorphology of the Himalayas, several studies have been carried out in NE India to develop earthquake-resistant civil structures for geohazard risk assessment and mitigation planning [10][11][12][13][14][15][16][17][18]. Except for flood-mapping investigations, only a few attempts have been made to comprehend ground subsidence-based studies employing remote sensing techniques [3,18,19].…”

“…In terms of the seismo-tectonics, geology, and geomorphology of the Himalayas, several studies have been carried out in NE India to develop earthquake-resistant civil structures for geohazard risk assessment and mitigation planning [10][11][12][13][14][15][16][17][18]. Except for flood-mapping investigations, only a few attempts have been made to comprehend ground subsidence-based studies employing remote sensing techniques [3,18,19]. Generally, timereliant subsidence observations have relied on time-series approaches like Persistent Scatterer Interferometric Synthetic Aperture Radar (PSInSAR) [2,20] and small baseline (SB) interferometry [2,[21][22][23][24][25].…”