Catastrophic sediment pulses in the Pokhara Valley Nepal Fluvial terraces floodplains and alluvial fans are the main landforms to store sediments and to decouple hillslopes from eroding mountain rivers. Such low relief landforms are also preferred locations for humans to settle in otherwise steep and poorly accessible terrain. Abundant water and sediment as essential sources for buildings and infrastructure make these areas amenable places to live at. Yet valley floors are also prone to rare and catastrophic sedimentation that can overload river systems by abruptly increasing the volume of sediment supply thus causing massive floodplain aggradation lateral channel instability and increased flooding. Some valley fill sediments should thus record these catastrophic sediment pulses allowing insights into their timing magnitude and consequences. This thesis pursues this theme and focuses on a prominent ~150 km2 valley fill in the Pokhara Valley just south of the Annapurna Massif in central Nepal. The Pokhara Valley is conspicuously broad and gentle compared to the surrounding dissected mountain terrain and is filled with locally more than 70 m of clastic debris. ...