Characterization of Sinkholes Affected Area of Thulibeshi Phat, Armala, Kaski, Nepal

Abstract

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.

Quantifying the Spatiotemporal Pattern of Urban Expansion and Hazard and Risk Area Identification in the Kaski District of Nepal

“…Similarly, various locations within the Pokhara-Lekhnath Metropolitan City have experienced land subsidence. Pokhrel [54], Rijal [55], and Rimal et al [8] have reported the highly susceptible areas to land subsidence.…”

“…Land collapse, land subsidence, and sinkhole hazards are most prominent within Pokhara City [54]. Thulibesi phant in Armala, where 117 sinkhole spots were observed, is exposed to severe sinkhole hazards [55]. Sarangakot and Kaskikot within the Phewa watershed [56] and the Rupakot area of the Rupa watershed [57] are prone to landslide hazards.…”

“…A detailed geographical study of Pokhara, Kaski was carried out by Gurung in 1965 [66]. Yet, there are few studies have assessed the hazard risk scenario [54][55][56][57][58] and urbanization trends [67,68] of Pokhara City and the Seti watershed [8]. However, long-term time-series studies of urbanization and the hazard risk of the entire Kaski District is lacking.…”

Land Use/Land Cover Change Detection in Pokhara Metropolitan, Nepal Using Remote Sensing

“…The frequent naturally-occurring of sinkholes changing the different land use patterns and overall decreasing overall productivity (Rijal, 2017). The problem arises from the hazardous expansion of the urban centre, lacking standard norms and regulations, improper spatial planning and unwanted population growth is the need of the present time.…”

Seasonal Variation of Springwater In-Situ Parameters in the Bhusundi Catchment, Gorkha, Nepal

“…In the study conducted in the land subsidence site of Armala, Kaski, Nepal; it was mentioned that water chemistry depends upon the surrounding rocks of sub-surface water (Rijal, 2017). Additionally, Gautam and Bhattarai (2008) suggested that the physical and chemical characteristics of waters in reservoirs were influenced by seasonal fluctuations in water and also by agricultural runoff.…”