The area affected by sinkholes in Thulibeshi Phat of Armala VDC, Pokhara was studied in order to
understand natural settings of the study area. A total of 117 sinkholes from depth range of 1 to 5 m and
diameters from 1 to 15.2 m were observed at the time of our field visit. Out of these sinkholes, 52 sinkholes
were filled sinkholes, 12 were water-bearing sinkholes and others were opened sinkholes. The area consists
of sediments of fluvio-lacustrine and debris deposits and the sinkhole site has sediments mainly of silt, clay
and fine sand size with chemical compositions of kaolin of major silica and minor constituents of calcium
carbonate. The main mechanism of formation of sinkholes in Thulibeshi Phat was washed-away effect
generated by piping mechanism of fine sediments by sub-surface flowing water, which was initiated by
partial dissolution of carbonate containing sediments. Human impact on landscape, especially land use
changes and stream channel modifications accelerated the process of piping mechanism for initiating and
extending the sinkhole affected area in the present study site. This study will help to understand how
geological conditions and human impacts interact to form sinkhole hazards in Nepal.