Author(s): Mahendra B. Baniya; Takeshi Fujino; Rocky Talchabhadel; Arjun Baniya; Naba Raj Sharma; K. C. Shivaram

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Keywords: Sediment transport; High-gradient rivers; Hydraulic parameters; Boulder movements

Abstract: Understanding sediment transport in river systems is essential for a wide range of disciplines, such as hydrology, geomorphology, risk management, and reservoir management. The sediment yield from a catchment is modulated by various parameters, including topography, slope, river gradient, river cross section, rainfall, temperature, and soil type. However, the sediment flux is a catchment response due to a combination of weathering, landslides, and glacial and fluvial erosions, which is complex and varies seasonally and annually. In Nepal, precipitation is primarily governed by the monsoon, with 80% of total annual precipitation occurring from June to September. Outbursts of glaciers and moraine dam failures can lead to flash floods, which can cause large boulders to be transported in high-gradient rivers in mountainous areas. This study evaluated key hydraulic parameters- shear stress, specific stream power, and flow velocity- for sediment transport in Kali Gandaki (KG) River at Setibeni, Syangja. It was found that monsoonal fluvial discharge and landslide dam outburst flood are responsible for boulder movements in the KG River. The lower boundary equation derived from a broad range of observed and computed data sets estimates the maximum boulder size of 840 mm could be transported by the monsoonal fluvial discharge from 2003 to 2011.

DOI: https://doi.org/10.3850/978-90-833476-1-5_iahr40wc-p1696-cd

Year: 2023