About 83% of Nepal is made up of mountains, which have a weak geological structure and a zone of active tectonic plates. Therefore, landslides and slope failure are common in Nepal. Numerous settlements, including villages, are located on or close to hazardous slopes that occasionally reignite landslides. The Nepal earthquake caused numerous landslides, which resulted in a tremendous loss of life, livestock, and infrastructure. The main natural disaster in Nepal that affects the economy and human population is a landslip. Among many harms, it has a major impact on highways of hilly areas in which Prithvi highway from Narayanghat to Muglin is one of it.
The Narayanghat-Mugling road is a vital link between the capital city, Kathmandu, and the outside world via the Terai region. It was built by the Chinese government from 1978 to 1982. About 90% of daily goods, materials, and fuel are transported through this route. However, the road frequently faces landslides, especially during the monsoon, disrupting transportation and impacting the economy. The road was expanded in 2019, but landslide prevention measures seem lacking. With social media showing frequent landslides and vehicle struggles, the road's importance has grown, but long-term solutions have been neglected by the government.
The occurrence of landslides along the Prithvi Highway (Mugling-Narayanghat road) can be attributed to a confluence of factors. A lot of rain can saturate the soil, which can make slopes unstable and cause landslides. Substantial rainfall has the potential to saturate the soil, rendering slopes susceptible to instability and consequent landslides. Geological attributes specific to the region, such as the presence of fractured or brittle rock formations, can amplify the propensity for slope displacement. Unregulated deforestation practices, carried out without the implementation of adequate soil conservation measures, can significantly compromise the soil's structural integrity, thereby escalating the vulnerability to landslides. The utilization of suboptimal construction methodologies, particularly on steep gradients, can disrupt the innate stability of the terrain, giving rise to landslides as a result. Landslides can be caused by human activity such as mining, road construction, or excavation that upsets the slope's natural equilibrium. More frequent and catastrophic landslides may occur as a result of altered weather patterns and an increase in extreme events brought on by climate change.
Landslides in highway areas of hilly regions in Nepal can have significant and wide-ranging impacts. Thus numerous issues can be observed in the Mugling - Narayanghat highway as it is the main roadways for traveling and transporting goods and services from Kathmandu to other districts and vice versa. Landslides significantly impact travelers with transportation disruptions, isolating towns and delaying commerce due to blocked highways. These events trigger economic setbacks and hinder emergency responses, while infrastructure damage, including roads and bridges, demands costly repairs and ongoing maintenance. Human casualties can occur if individuals or vehicles are caught in debris flows. Beyond immediate effects, long-term financial repercussions arise from highway closures that disrupt local businesses relying on efficient routes. Ecologically, landslides cause soil erosion, habitat loss, and altered water dynamics. Their proximity to highways increases future incident likelihood, amplifying vulnerability and posing persistent safety challenges.
To reduce the risk of landslides in these areas, it's critical that the government employ sound land-use planning, slope stabilization measures, and early warning systems. Establishing reliable early warning systems that can foresee and warn populations about future landslides is essential for dealing with these effects and reducing their occurrence. Additionally, by employing efficient slope stabilization techniques and practicing sound land-use planning, roadway areas in mountainous locations can be made much less susceptible to landslides. To reduce hazards and improve these regions' resilience to landslip events, a thorough and proactive strategy is required. One of the simplest yet effective measures to mitigate landslides in highways of hilly areas is implementation of the afforestation methods. This helps to increase the shear strength of slope and decrease the shear stress which keeps the top layer of soil in equilibrium making the slope stable and preventing it from eroding.