Development of a Precipitation-Induced Moisture-Driven Landslide Threshold Atlas for the Northwestern and Northeastern Himalayas

Landslides remain a major hazard across the Himalayan terrain, driven by extreme precipitation, cloudbursts, antecedent moisture, and heterogeneous environmental conditions. However, spatiotemporal trends of at-site precipitation–induced moisture–driven landslide (PML) thresholds remain poorly understood for the Indian Himalayan region. Here, compiling archived 1109 PML records from 2007–2018, for the first time, to the best of our knowledge, we present an event-duration (ED) PML threshold atlas across the northwestern (NWH) and northeastern Himalayan (NEH) regions of India. We employ gauge-merged high-resolution (0.25°) gridded rainfall observations in a noncrossing quantile regression framework to develop physically informed ED thresholds across at-site and regional scales. Over 2007–2018, the annual frequency of PMLs shows a statistically insignificant modest upward trend (≈0.5 events year−1). The PML occurrences show distinct seasonality: ∼68% of events observed during the June–September Southwest monsoon season. Conversely, ∼35% of stations, spatially concentrated along the upper Jhelum corridor in the Kashmir Valley and adjoining Pir Panjal foothills in the NWH, show a higher frequency of PML during January to April, likely due to the influence of Western Disturbances. The accumulated PML threshold in the NWH reveals a marked spatial heterogeneity, while the NEH, typically covered with dense vegetation, shows spatially homogeneous at-site thresholds. The regional contrast in PML threshold arises due to differences in terrain aspect and land use/land cover patterns, which are identified as key controls for PML threshold variability. The updated PML thresholds show notable differences and improved predictability compared to the previously reported global and local rainfall thresholds, which were derived using the ordinary least squares regression method. The PML threshold atlas, developed for the Indian Himalayan region, serves as a foundational tool for landslide early warning, disaster risk reduction, and climate adaptation efforts in high-mountain Asia.