Nepal sits on a geological collision zone where the Indian Plate pushes into the Eurasian Plate. This tectonic activity creates constant stress, making the Himalayas inherently unstable. Natural seismic events remain the primary driver of mass wasting in the region. However, hydropower development changes how the earth responds to these stresses.
Construction activities, such as excavation for access roads and tunneling, cut directly into steep, fragile slopes. This removes the toe of the slope, which often triggers shallow landslides. Furthermore, the cyclical loading caused by reservoir filling and emptying—often called reservoir-induced seismicity or pore-water pressure fluctuations—weakens the internal friction of the soil. When water levels drop rapidly, the heavy weight of the stored water disappears, but the water trapped deep inside the soil remains, keeping the slope saturated and prone to sliding.
While tectonics provide the underlying tension, human-made infrastructure acts as a catalyst. A landslide that might have stayed dormant for decades can be triggered much sooner by a poorly drained construction site or a fluctuating reservoir. We are seeing more frequent, localized failures that stem from engineering footprints rather than large-scale crustal shifts.
